EXPANSION OF MADABA WASTEWATER TREATMENT PLANT …

EXPANSION OF MADABA WASTEWATER TREATMENT PLANT

FEASIBILITY STUDY REPORT – TASK 4

USAID Jordan Water Infrastructure

Prepared by CDM International for United States Agency for International Development underGlobal Architect – Engineer Services II IDIQ

USAID Contract No. AID-OAA-I-15-00047

Order: 72027818F00002

The Hashemite Kingdom of JordanMinistry of Water and IrrigationWater Authority of Jordan (WAJ)

Date June 30, 2020 - Draft April 12, 2021 - Final

This publication was produced for review by the United States Agency for International Development. It was prepared by CDM Smith.

Project: USAID Jordan Water Infrastructure

Contract: Global Architect – Engineer Services II IDIQ

USAID Contract No. AID-OAA-I-15-00047Order: 72027818F00002

Expansion of Madaba WWTP – Task 4Final Feasibility Study Report

Prepared by:John Crippen, PE; Travis Meyer, PE;

Melissa Woo, PE; Eng. Sawsan Bataineh; Eng. Ali Yousef, and Theresa Jurotich

Date: May 28, 2020

Reviewed by: Richard Tsang, PhD, PE; William McConnell, PE; Misti Burkman, PE; Ron Miner, PE; Matt Antill Date: June 1, 2020

Approved by: Rick Minkwitz Date: June 28, 2020

Finalized by:

John Crippen, PE; Travis Meyer, PE; Eng. Sawsan Bataineh

Incorporation of MWI/WAJ and USAID commends on the draft report

Date: April 15, 2021

Disclaimer

This study/publication/other information product is made possible by the generous support of the American people through the United States Agency for International Development (USAID). The contents of this report do not necessarily reflect the views of USAID or the United States Government.

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Table of Contents

Executive Summary......................................................................................................xviiES 1 Background.............................................................................................................................................xvii

ES 1.1 Existing Conditions..........................................................................................................................xviiiES 1.2 Prior Studies.......................................................................................................................................xviii

ES 2 Wastewater Treatment Plant Expansion ....................................................................................xixES 2.1 Wastewater Flows and Loads Projections.........................................................................xixES 2.2 Effluent and Biosolids Standards...........................................................................................xixES 2.3 Wastewater Treatment Alternatives....................................................................................xixES 2.4 Selected Alternative.....................................................................................................................xxi

ES 3 Next Steps.................................................................................................................................................xxx

Section 1 Introduction .....................................................................................................11.1 Summary of the USAID Jordan Water Infrastructure................................................................1

1.1.1 Scope of the Feasibility Study .....................................................................................................21.1.2 Report Organization........................................................................................................................31.1.3 Flow Terminology............................................................................................................................4

1.2 Background..................................................................................................................................................41.2.1 Plant Location....................................................................................................................................51.2.2 Plant History and Existing Plant Description.......................................................................71.2.3 Other Programs at Madaba WWTP ..........................................................................................81.2.4 Exiting Wastewater Treatment Plant Flows and Loads ..................................................91.2.5 Wastewater Collection Network.............................................................................................111.2.6 Effluent and Solids Reuse...........................................................................................................131.2.7 Climate ...............................................................................................................................................13

Section 2 Summary of Wastewater Flows and Loads .....................................................152.1 Madaba WWTP Catchment Area......................................................................................................15

2.1.1 Al-Dar Al-Arabia Consultants Study......................................................................................152.1.2 Potential Additional Wastewater Network Expansion .................................................152.1.3 Plant Influent Flow Lag...............................................................................................................212.1.4 Wastewater Flow Variations ....................................................................................................212.1.5 Summary of Wastewater Flow Projections........................................................................22

2.2 Wastewater Load Projections ...........................................................................................................232.3 Summary of Projected Wastewater Flows and Loads............................................................23

2.3.1 Methodology....................................................................................................................................232.3.2 Influent Flows and Loads...........................................................................................................252.3.3 Peak Hourly Flow ..........................................................................................................................28

Section 3 Treatment Requirements and Effluent Standards ...........................................293.1 Introduction..............................................................................................................................................293.2 Jordanian Effluent and Sludge Disposal Standards .................................................................29

3.2.1 Standards for Wastewater Discharges and Effluent Reuse.........................................293.2.2 Total Nitrogen Treatment Requirements and Concerns..............................................313.2.3 Total Dissolved Solids and Requirements and Concerns.............................................333.2.4 Industrial Effluent Standard .....................................................................................................333.2.5 Jordanian Standards for Treated Sludge and Sludge Disposal (JS1145/2016)..33

3.3 Current Disposal Practices and Considerations........................................................................353.3.1 Current Sludge Disposal Practices .........................................................................................35

TOC Table of Contents

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3.3.2 Sludge Reuse Considerations ...................................................................................................363.4 Jordan Air Emission Discharge Standard.....................................................................................36

3.4.1 Requirements..................................................................................................................................363.4.2 Air Emission Limits at WWTP..................................................................................................38

3.5 Energy Efficiency and Renewable Energy Policy......................................................................383.5.1 Policy Targets until 2025...........................................................................................................383.5.2 Project Objectives of the Energy Efficiency and Renewable Energy.......................403.5.3 Energy Sector Strategy 2020 - 2030 .....................................................................................41

Section 4 Existing WWTP Condition Assessment............................................................434.1 Condition Assessment Task ...............................................................................................................43

4.1.1 Background ......................................................................................................................................434.2 Condition Assessment Summary .....................................................................................................44

4.2.1 Plant Treatment Performance .................................................................................................444.2.2 Plant Infrastructure......................................................................................................................444.2.3 Operations and Maintenance Management .......................................................................45

Section 5 Assessment of Treatment Technologies..........................................................475.1 Introduction..............................................................................................................................................47

5.1.1 How This Section is Organized ................................................................................................475.1.2 Objectives..........................................................................................................................................47

5.2 Wastewater Liquid Stream Treatment Technologies.............................................................475.2.1 Plug Flow Reactors with Diffused Aeration .......................................................................485.2.2 Oxidation Ditch with Fine Bubble Aeration .......................................................................495.2.3 Sequencing Batch Reactor .........................................................................................................515.2.4 Other Liquid Stream Treatment Process.............................................................................525.2.5 Phosphorus Removal Methods and Recommendation .................................................535.2.6 Liquid Stream Treatment Alternatives ................................................................................53

5.3 Wastewater Solids Stream Treatment Technologies..............................................................575.3.1 Conventional Anaerobic Digestion ........................................................................................585.3.2 Covered In-Ground Anaerobic Reactor................................................................................645.3.3 Digester Gas Utilization for Electricity Generation.........................................................665.3.4 Lime Stabilization..........................................................................................................................705.3.5 Aerobic Sludge Digestion ...........................................................................................................725.3.6 Sludge Drying Beds.......................................................................................................................725.3.7 Solids Stream Treatment Alternatives .................................................................................735.3.8 Evaluation of Liquid-Solid Stream Treatment Processes ............................................76

5.4 Preliminary Treatment/Headworks ..............................................................................................765.4.1 Septage Receiving..........................................................................................................................765.4.2 Rock Trap..........................................................................................................................................775.4.3 Influent Mechanical Screens.....................................................................................................795.4.4 Grit Removal ....................................................................................................................................83

5.5 Odor Control .............................................................................................................................................865.5.1 Odor Control Alternatives..........................................................................................................875.5.2 Biotrickling Filter ..........................................................................................................................875.5.3 Biofilter ..............................................................................................................................................885.5.4 Summary and Recommendation ............................................................................................89

5.6 Primary Sedimentation........................................................................................................................895.7 Effluent Treatment.................................................................................................................................91

5.7.1 Effluent Disinfection.....................................................................................................................91


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5.7.2 Effluent Filter ..................................................................................................................................935.7.3 Plant Water Supply .......................................................................................................................93

5.8 Biosolids Processing Options ............................................................................................................935.8.1 Primary Sludge and Septage Screening ...............................................................................935.8.2 Biosolids Thickening....................................................................................................................955.8.3 Biosolids Dewatering Technologies ......................................................................................985.8.4 Sludge Disposal............................................................................................................................103

Section 6 Assessment of Effluent and Biosolids Reuse .................................................1056.1 Effluent Reuse Options ......................................................................................................................105

6.1.1 Existing Effluent Reuse.............................................................................................................1056.1.2 South Amman WWTP Treated Effluent Reuse...............................................................106

6.2 Biosolids Reuse Options ...................................................................................................................1066.3 Effluent Reuse Options and Infrastructure...............................................................................106

6.3.1 Effluent Reuse Option I – Status Quo .................................................................................1066.3.2 Effluent Reuse Option II – Effluent Pumping to the Jordan Valley for Irrigation .1076.3.3 Effluent Reuse Option III – Long-Term Effluent Storage for Local Irrigation ..1086.3.4 Fodder Irrigation in South Amman Area..........................................................................1116.3.5 Madaba and South Amman WWTPs Combined Effluent Reuse .............................1116.3.6 Options Considered, But Not Evaluated............................................................................1116.3.7 Recommended Effluent Reuse ..............................................................................................112

Section 7 Financial and Economic Analysis...................................................................1137.1 Financial Analysis Overview...........................................................................................................113

7.1.1 Projected Flows ...........................................................................................................................1137.1.2 Expenses .........................................................................................................................................1147.1.3 Annual Revenue Estimates .....................................................................................................1207.1.4 Cash Flow Analysis.....................................................................................................................1217.1.5 Financial Analysis of Options for Additional Effluent Reuse ...................................1267.1.6 Financial Risk Analysis.............................................................................................................1317.1.7 Financial Analysis Conclusions.............................................................................................131

7.2 Economic Analysis...............................................................................................................................1327.2.1 Methodology .................................................................................................................................1327.2.2 Annual Volumes and Flows ....................................................................................................1347.2.3 Implementation Costs...............................................................................................................1377.2.4 Benefits............................................................................................................................................1387.2.5 Economic Feasibility .................................................................................................................140

Section 8 Evaluation of Treatment Alternatives ...........................................................1458.1 Short-Listing of Treatment Alternatives....................................................................................145

8.1.1 Short-Listed Combined Liquid/Solid Stream Alternatives.......................................1458.2 Assessment of Process Treatment Alternatives.....................................................................145

8.2.1 Assessment Criteria ...................................................................................................................1468.2.2 Category and Subcategory Weights ....................................................................................1518.2.3 Sustainability Score ...................................................................................................................1538.2.4 Conceptual Opinion of Probable Construction Cost ....................................................154

8.3 Evaluation Results and Recommendations ..............................................................................1548.3.1 Summary of Costs by Alternatives ......................................................................................1548.3.2 Alternatives Lifecycle Costs....................................................................................................1608.3.3 Conclusions and Recommendations...................................................................................161

Section 9 Summary of Treatment Recommendations...................................................165


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8.4 General Liquid Treatment Stream Design Criteria................................................................1668.4.1 Plant Hydraulics ..........................................................................................................................1668.4.2 Septage Unloading Station......................................................................................................1668.4.3 Rock Trap .......................................................................................................................................1698.4.4 Bypass to Wadi.............................................................................................................................1698.4.5 Influent Screening ......................................................................................................................1698.4.6 Flow Measurement (Parshall flume)..................................................................................1718.4.7 Influent Stormwater Management......................................................................................1718.4.8 Grit and Grease Removal .........................................................................................................1728.4.9 Odor Control .................................................................................................................................172

8.5 General Solids Stream Design Criteria........................................................................................1748.5.1 Sludge Stabilization ...................................................................................................................1748.5.2 Digester Gas System ..................................................................................................................1788.5.3 Digester Gas Energy Recovery System..............................................................................1798.5.4 Sludge Dewatering in Drying Beds......................................................................................1828.5.5 Mechanical Sludge Dewatering.............................................................................................1828.5.6 Sludge Disposal............................................................................................................................1838.5.7 Ancillary Processes and Support Systems .......................................................................183

8.6 Plant Support Facilities .....................................................................................................................1838.6.1 Buildings.........................................................................................................................................1838.6.2 General Site Civil .........................................................................................................................1848.6.3 Maintenance of Plant Operations.........................................................................................184

8.7 Reuse of Existing Plant Infrastructure........................................................................................1848.7.1 Existing Aeration Tanks...........................................................................................................1848.7.2 Existing Secondary Clarifiers.................................................................................................1858.7.3 Headworks.....................................................................................................................................1868.7.4 Polishing Ponds and Rock Filter...........................................................................................1868.7.5 Chlorine Contact Tank and Building...................................................................................1878.7.6 Effluent Storage Pond ...............................................................................................................1878.7.7 Sludge Gravity Thickener Tanks ..........................................................................................1878.7.8 Drying Beds ...................................................................................................................................187

Section 10 WWTP Expansion Implementation Program ...............................................1899.1 Introduction ...........................................................................................................................................1899.2 Preparation of Detailed Design and Tender Documents ....................................................189

9.2.2 Land Acquisition .........................................................................................................................1909.2.3 Topographical Survey and Soil Investigations...............................................................1909.2.4 Department of Antiquities Approval to Proceed...........................................................1909.2.5 Ministry of the Environment Approval to Proceed......................................................1919.2.6 Basis of Design Report..............................................................................................................1919.2.7 Detailed Design Development...............................................................................................1919.2.8 Preparation of Tender Documents – Design, Bid, and Build....................................1929.2.9 Engineer’s Cost Estimates.......................................................................................................1939.2.10 Prequalification Documents...................................................................................................1939.2.11 Project Summary Report .........................................................................................................193

9.3 Project Schedule...................................................................................................................................1939.4 Construction Contract Procurement and Construction Management ..........................194

9.4.1 Prequalification of Contractors ............................................................................................1949.4.2 Precontract Services..................................................................................................................1949.4.3 Evaluation of Bids and Award of Contract.......................................................................195


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9.4.4 Construction..................................................................................................................................1959.4.5 Commissioning ............................................................................................................................195


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List of FiguresFigure 1-1 Madaba WWTP Location ..........................................................................................................................................5

Figure 1-2 Madaba WWTP Site and Area Available for Expansion ..............................................................................6

Figure 1-3 Existing Madaba WWTP Site Plan ........................................................................................................................6

Figure 1-4 Existing Madaba WWTP Process Flow Block Diagram ...............................................................................8

Figure 1-5 Madaba City Existing Wastewater Network..................................................................................................12

Figure 2-1 Madaba City Planned Wastewater Network Expansion by Al-Dar Al-Arabia Study (2017) ....16

Figure 2-2 Madaba City Wastewater Network Catchment with Existing, Planned, and Potential Networks ...................................................................................................................................................................................17

Figure 2-3 Madaba Wastewater Influent Flow Projections Graph ............................................................................20

Figure 2-4 Madaba Wastewater Diurnal Influent Flow ..................................................................................................22

Figure 2-5 Madaba WWTP Operation Range ......................................................................................................................28

Figure 5-1 Process Schematic of a Modified Ludzack-Ettinger MLE Process with Plug Flow Reactors....49

Figure 5-2 Typical Oxidation Ditch Process Schematic ..................................................................................................50

Figure 5-3 Sequencing batch reactor schematic ................................................................................................................51

Figure 5-4 Conventional Anaerobic Digestion Schematic..............................................................................................59

Figure 5-5 Concrete Cylinder Digester Tank (Left) with Fixed Steel Cover (Ovivo) and Egg-Shaped Digester Tanks ........................................................................................................................................................................61

Figure 5-6 Sludge Tube-in-Tube Heat Exchanger (Wes-Tech)....................................................................................63

Figure 5-7 Process Flow Diagram Covered In-Ground Anaerobic Reactor............................................................65

Figure 5-8 Digester Gas Utilization Schematic....................................................................................................................66

Figure 5-9 Digester Gas Membrane Storage Holder (Left, Evoqua) and Open Waste Gas Burner (Varec)........................................................................................................................................................................................................68

Figure 5-10 Digester Gas Cleaning System...........................................................................................................................69

Figure 5-11 Digester Gas Engine Generator (Jenbacher)...............................................................................................70

Figure 5-12 Sludge Lime Stabilization Schematic (Oerke and Rogowski, 1990).................................................71

Figure 5-13 Rock Trap Concept.................................................................................................................................................78

Figure 5-14 Rock Trap Clamshell with Electric Hoist and Monorail.........................................................................79

Figure 5-15 Multi-Rake Screen..................................................................................................................................................80

Figure 5-16 Reciprocating Screen............................................................................................................................................80

Figure 5-17 Continuous Element screen...............................................................................................................................81

Figure 5-18 Stair (Step) Screen .................................................................................................................................................81

Figure 5-19 Helical basket screen ............................................................................................................................................82

Figure 5-20 Vortex Grit Removal System..............................................................................................................................84

Figure 5-21 Aerated Grit Removal System...........................................................................................................................85

Figure 5-22 Aerated Grit and Grease Removal System Sketch....................................................................................86

Figure 5-23 Bioscrubber ..............................................................................................................................................................87

Figure 5-24 Biofilter Odor Control Unit.................................................................................................................................88

Figure 5-25 A Circular Primary Clarifier at the East Jerash WWTP ..........................................................................90


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Figure 5-26 Coarse Material Separator by Huber Technology ....................................................................................94

Figure 5-27 Gravity Belt Thickener .........................................................................................................................................95

Figure 5-28 Gravity Thickener...................................................................................................................................................96

Figure 5-29 Rotary Drum Thickener.......................................................................................................................................97

Figure 5-30 Dewatering Screw Press .....................................................................................................................................99

Figure 5-31 Dewatering Centrifuge ......................................................................................................................................100

Figure 5-32 Belt Filter Press ....................................................................................................................................................101

Figure 6-1 Long-Term Effluent Storage Pond Compared to the WWTP Site ......................................................110

Figure 7-1 Implementation Costs and Cost-Saving Benefits......................................................................................133

Figure 9-1 Septage Unloading Station at South Amman WWTP ..............................................................................168

List of TablesTable ES-1 Madaba WWTP Technical Committee Comments and Responses.....................................................xxi

Table ES-2 Strategies to Mitigate WWTP Operational Complexity ........................................................................xxiv

Table ES-3 Alternative C.1A – Capital Costs (US$) ..........................................................................................................xxv

Table ES-4 Alternative C.1A – Annual O&M Cost Projection.......................................................................................xxv

Table ES-5 Opinion of Probable Contractor’s 3-year O&M Costs (US$1000) ...................................................xxvii

Table ES-6 WWTP Expansion Facilities – Liquid Steam ...........................................................................................xxviii

Table ES-7 WWTP Expansion Facilities – Solids Steam...............................................................................................xxix

Table ES-8 WWTP Expansion Facilities – Supporting Facilities................................................................................xxx

Table 1-1 Project Stages and Status ...........................................................................................................................................3

Table 1-2 Historic Influent Flow Measurements 2015–2018.........................................................................................9

Table 1-3 Existing Madaba WWTP Design Basis and 2018 Sampling Results......................................................10

Table 2-1 Madaba WWTP AADF, Total Population, Service Population, AAD BOD5 Loading, and BOD5 Contribution.............................................................................................................................................................................18

Table 2-2 Population Served by Wastewater Network and Madaba WWTP Expansion1................................19

Table 2-3 Wastewater Contribution by Network Status1 ..............................................................................................20

Table 2-4 Wastewater Contribution by Network Status1 ..............................................................................................21

Table 2-5 Influent Peaking Factors, Flows, and Loads....................................................................................................25

Table 2-6 Primary Clarifier Removal Efficiencies Used..................................................................................................26

Table 2-7 Madaba WWTP Septage Flows and Loads for 2045 ....................................................................................27

Table 3-1 Characteristics of Effluent for Reuse (Categories 1 to 3)1.........................................................................30

Table 3-2 Allowable Limits for Effluent for Wadi Disposal, Aquifer Recharge, and Irrigation......................30

Table 3-3 Maximum Concentrations Allowed in Biosolids ...........................................................................................34

Table 3-4 Annual Application Rates and Maximum Accumulation Limits in Soil ...............................................34

Table 3-5 Maximum Allowable Limits for Total Particulate Emission from Stationary Sources .................37

Table 3-6 Maximum Emission Limits for Gases and Vapors ........................................................................................37

Table 5-1 BNR Activated Sludge Advantages and Disadvantages..............................................................................49

Table 5-2 Advantages and Disadvantages of Oxidation Ditches .................................................................................51


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Table 5-3 Sequencing Batch Reactor Advantages and Disadvantages .....................................................................52

Table 5-4 Liquid Stream Treatment Technologies Not Short-Listed........................................................................53

Table 5-5 Conventional Anaerobic Digestion Advantages and Disadvantages ....................................................59

Table 5-6 Recirculation Pump Mixing Advantages and Disadvantages...................................................................62

Table 5-7 Mechanical Linear Motion Mixing Advantages and Disadvantages......................................................63

Table 5-8 Covered In-Ground Anaerobic Reactor Advantages and Disadvantages ...........................................65

Table 5-9 Digester Gas Utilization System Advantages and Disadvantages ..........................................................66

Table 5-10 Sludge Lime Stabilization Advantages and Disadvantages....................................................................71

Table 5-11 Aerobic Digestion Advantages and Disadvantages ...................................................................................72

Table 5-12 Sludge Drying Bed Advantages and Disadvantages ..................................................................................73

Table 5-13 Vortex Grit Removal System Advantages and Disadvantages..............................................................84

Table 5-14 Aerated Grit Chamber Advantages and Disadvantages...........................................................................85

Table 5-15 Wastewater Odorants ............................................................................................................................................86

Table 5-16 Biotrickling Filter Advantages and Disadvantages....................................................................................88

Table 5-17 Biofilter Advantages and Disadvantages .......................................................................................................89

Table 5-18 Rectangular Primary Clarifier Advantages and Disadvantages ...........................................................90

Table 5-19 Circular Primary Clarifier Advantages and Disadvantages ...................................................................90

Table 5-20 Effluent Disinfection Options Advantages and Disadvantages ............................................................92

Table 5-21 Horizontal Cylindrical Coarse Material Separator Advantages and Disadvantages ...................94

Table 5-21 Gravity Belt Thickeners Advantages and Disadvantages .......................................................................96

Table 5-22 Gravity Thickeners Advantages and Disadvantages.................................................................................97

Table 5-23 Rotary Drum Advantages and Disadvantages .............................................................................................98

Table 5-24 Screw Presses Advantages and Disadvantages...........................................................................................99

Table 5-25 Centrifuge Advantages and Disadvantages................................................................................................100

Table 5-26 Belt Press Advantages and Disadvantages.................................................................................................101

Table 5-27 Drying Bed Advantages and Disadvantages ..............................................................................................102

Table 7-1 Projected Annual Influent Flow to Madaba WWTP, MCM......................................................................113

Table 7-2 Reuse Option I Projected Effluent Available to Farmers (MCM).........................................................114

Table 7-3 Capital Cost Estimates, US$1000.......................................................................................................................114

Table 7-4 Capital Cost Estimates to be Covered Through Debt Service, US$1000...........................................115

Table 7-5 Capital Cost by Funding Source, US$1000 ....................................................................................................115

Table 7-6 Projected Debt Service by Alternative, US$1000 .......................................................................................116

Table 7-7 Projected Salary by Alternative, US$1000 ....................................................................................................116

Table 7-8 Projected Electric Consumption Rate by Process (kWh/m3) ...............................................................117

Table 7-9 Projected Net Electricity Cost by Alternative (US$1000).......................................................................117

Table 7-10 Chemical Unit Prices and Applicable Alternatives..................................................................................117

Table 7-11 Projected Liquids-Related Chemical Cost by Alternative (US$1000s)...........................................118

Table 7-12 Projected Solids Chemical Cost by Alternative (US$1000s) ...............................................................118

Table 7-13 Other Costs and Unit Prices ..............................................................................................................................118


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Table 7-14 Projected Truck-Hauling Costs by Alternative (US$1000s) ...............................................................119

Table 7-15 Projected Other Costs by Alternative (US$1000s)..................................................................................119

Table 7-16 Projected Renewal and Replacement Costs by Alternative (US$1000s) ......................................119

Table 7-17 Projected O&M Cost Summary by Alternative (US$1000s) ................................................................120

Table 7-18 Projected Revenue (US$1000s) ......................................................................................................................121

Table 7-19 Projected Cash Flow Alternative A.1 (US$1000s)...................................................................................121

Table 7-20 Projected Cash Flow Alternative B.1 (US$1000s)...................................................................................122

Table 7-21 Projected Cash Flow Alternative C.1 (US$1000s) ...................................................................................122

Table 7-22 Projected Cash Flow Alternative C.2 (US$1000s) ...................................................................................123

Table 7-23 Projected Cash Flow Alternative E (US$1000s).......................................................................................123

Table 7-24 Net Present Value (US$1000s) ........................................................................................................................124

Table 7-25 Modified Internal Rate of Return....................................................................................................................124

Table 7-26 Cost Recovery (US$1,000).................................................................................................................................124

Table 7-27 Capital Cost Estimates – Additional Effluent Reuse Options (US$1000) ......................................126

Table 7-28 Additional Effluent Reuse Option Capital Cost Estimates To Be Covered Through Debt Service (US$1000) ..............................................................................................................................................................126

Table 7-29 Additional Effluent Reuse Options Capital Cost by Funding Source (US$1000) .......................127

Table 7-30 Projected Debt Service by Additional Effluent Reuse Option (US$1000).....................................127

Table 7-31 Projected Effluent Pumping to Jordan Valley and to Local Farmers, Reuse Option II.............127

Table 7-32 Projected Effluent Pumping to Jordan Valley and to Local Farmers, Reuse Option III ...........128

Table 7-33 Projected Additional Effluent Reuse Option Electric Costs (US$1000) .........................................129

Table 7-34 Projected Additional Effluent Reuse Option Renewal and Replacement Costs (US$1000)..129

Table 7-35 Projected O&M Cost Summary by Effluent Reuse Option 2024–2045 (US$1000s).................129

Table 7-36 Projected Additional Effluent Reuse Options Revenues (US$1000)...............................................130

Table 7-37 Projected Additional Effluent Reuse Options Net Cash Flow (US$1000) .....................................130

Table 7-38 Net Present Value of Additional Effluent Reuse Options (US$1000)..............................................130

Table 7-39 Financial Risk and Mitigation Measures......................................................................................................131

Table 7-40 Scenarios of Plant Expansion and Storage/Pumping Options...........................................................133

Table 7-41 Population Projections by Subdistrict..........................................................................................................135

Table 7-42 Wastewater Projections by Locality (m3/d)..............................................................................................135

Table 7-43 Untreated Wastewater Projections – No-Build vs. Build (m3/d)......................................................136

Table 7-44 Annual Effluent and Waste Flows (MCM/y)..............................................................................................136

Table 7-45 Net Change in Effluent Agriculture Use (MCM/y)...................................................................................137

Table 7-46 WWTP Expansion Construction Costs - By Alternative........................................................................137

Table 7-47 WWTP Expansion O&M Cost - By Alternative ..........................................................................................138

Table 7-48 Storage and Pumping Construction Costs by Option.............................................................................138

Table 7-49 Storage and Pumping O&M Costs - By Option ..........................................................................................138

Table 7-50 Benefit Types and Estimation..........................................................................................................................140

Table 7-51 Summary Annual Benefits by Alternative and Option ..........................................................................140

Table 7-52 Summary Economic Feasibility Metrics by Alternative and Option ...............................................141


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Table 7-53 Summary Economic Feasibility Metrics by Alternative and Option (excl. Fertilizer) .............142

Table 7-54 Reuse Option Comparison Summary............................................................................................................142

Table 8-1 Short-Listed Combined Wastewater Treatment Alternative................................................................145

Table 8-2 Category and Subcategory Weight Values.....................................................................................................152

Table 8-3 Alternative A.1 – Average Annual O&M Costs (US$/y) for the Period 2023 through 2045 ....155

Table 8-4 Alternative A.1 – Capital Costs (US$) ..............................................................................................................155

Table 8-5 Alternative B.1 – Average Annual O&M Costs (US$/y) for the Period 2023 through 2045 ....155

Table 8-6 Alternative B.1 – Capital Costs (US$)...............................................................................................................156

Table 8-7 Alternative B.1A – Average Annual O&M Costs (US$/y) for the Period 2023 through 2045 .156

Table 8-8 Alternative B.1A – Capital Costs (US$)............................................................................................................156

Table 8-9 Alternative C.1 – Average Annual O&M Costs (US$/y) for the Period 2023 through 2045 ....157

Table 8-10 Alternative C.1 – Capital Costs (US$) ............................................................................................................157

Table 8-11 Alternative C.1A – Average Annual O&M Costs (US$/y) for the Period 2023 through 2045.....................................................................................................................................................................................................158

Table 8-12 Alternative C.1A – Capital Costs (US$) .........................................................................................................158

Table 8-13 Alternative C.2 – Average Annual O&M Costs (US$/y) for the Period 2023 through 2045..158


Table 8-15 Alternative C.3 – Average Annual O&M Costs (US$/y) for the Period 2023 through 2045..159


Table 8-17 Alternative E – Average Annual O&M Costs (US$/y) for the Period 2023 through 2045 .....160

Table 8-18 Alternative E – Capital Costs (US$)................................................................................................................160

Table 8-19 Net Present Value Life-Cycle Cost for the Alternatives (US$)............................................................161

Table 9-1 Septage Unloading Station ...................................................................................................................................169

Table 9-2 Thickened Sludge Flows and Loads .................................................................................................................175

Table 9-3 Thickened Sludge Pumps......................................................................................................................................175

Table 9-3 Anaerobic Digestion Design Criteria ...............................................................................................................176

Table 9-4 Anaerobic Digestion Flows and Loads............................................................................................................176

Table 9-5 Digester Withdrawal Pumps ...............................................................................................................................177

Table 9-6 Mechanical Linear Motion Mixing Design Criteria ....................................................................................177

Table 9-7 Digester Recirculation and Heating System Design Criteria.................................................................177

Table 9-8 Digested Sludge Storage Design Criteria........................................................................................................178

Table 9-9 Digester Gas Production........................................................................................................................................178

Table 9-10 Excess Gas Flare Design Criteria.....................................................................................................................179

Table 9-11 Gas Storage Holder Design Criteria ...............................................................................................................179

Table 9-12 Digester Gas Cleaning System Design Criteria..........................................................................................180

Table 9-13 Digester Gas Combined Heat and Power Design Criteria ....................................................................181

Table 9-14 Digester Gas Electrical and Heat Generation.............................................................................................181

Table 9-15 Digester Gas Backup Boiler Design Criteria...............................................................................................181

Table 9-16 Example of Using Multiple Drying Bed Fill/Dry Cycles ........................................................................182

Table 10-1 Expansion of Madaba WWTP Work Plan....................................................................................................193


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AppendicesAppendix A Madaba WWTP Water and Biosolids Reuse Study

Appendix B Technical Memorandums

Appendix C Basis of Cost Estimates

Appendix D Drawings, Feasibility Study

Appendix E Alternatives Evaluation Matrix

Appendix F Financial – Chemical Use

Appendix G Financial – Cash Flows

Appendix H Financial – Process Flows

Appendix I Economic – Benefit-Cost Ratio Scenario Tables

Appendix J Draft Report – Communications and Comments


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List of AbbreviationsAAD Average Annual DailyAADF Annual Average Daily FlowAADL Annual Average Daily LoadADDWF Average Daily Dry Weather FlowADMM Average Day Maximum MonthADMMF Average Day Maximum Month FlowAJ Arabtech JardanehAW Aqaba Water CompanyBCA Benefit-Cost AnalysisBCR Benefit-Cost RatioBEO Bureau Environmental OfficerBNR Biological Nutrient RemovalBODR Basis of Design ReportBOQ Bill of QuantitiesBOT Build, Operate and TransferCAD Conventional Anaerobic DigestionCAS Conventional Activated SludgeCDM Smith CDM Smith and CDM International Inc.CHP Combined Heat and PowerCIGAR Covered In-Ground Anaerobic ReactorCOR Contract Officer RepresentativeCC Consolidated Consultants for Engineering and EnvironmentCCT Chlorine Contact TankCMS Construction Management ServicesDAF Dissolved Air FlotationDEC Development Experience Clearinghouse DDL USAID’s Development Data Library DLS Department of Land SurveyDOS Department of StatisticsEA Environmental AssessmentEIA Environmental Impact AssessmentESIA Environmental and Social Impact AssessmentFARA Fixed Amount Reimbursable AgreementFIDIC International Federation of Consulting EngineersGBT Gravity Belt ThickenerGIS Geographical Information SystemGIZ German Corporation for International Cooperation GmbHGOJ Government of JordanGTD Government Tenders DepartmentHI Hydraulic InstituteHRT Hydraulic Retention TimeIC Internal CombustionIEE Initial Environmental ExaminationIR Intermediate ResultIRR Internal Rate of ReturnJD Jordanian DinarsJS Jordanian Standard


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KaMP USAID/Jordan Knowledge Management PortalMCM Million Cubic MetersMD Maximum DayMDF Maximum Day FlowMEL Monitoring Evaluation and LearningMEO Mission Environmental OfficerMLE Modified Ludzack-EttingerMoA Ministry of AgricultureMoE Ministry of EnvironmentM&E Monitoring & EvaluationMLSS Mixed Liquor Suspended SolidsMPWH Ministry of Public Works and HousingMoPIC Ministry of Planning and International CorporationMOPO Maintenance of Plant OperationsMWC Jordan Water Company - MiyahunaMWI Ministry of Water and Irrigation NPV Net Present ValueNRW Non-Revenue WaterO&M Operation and MaintenanceOMB United States Office of Management and BudgetOPCC Opinion of Probable Construction CostPHF Peak Hourly FlowPSP Private Sector ParticipationPMU Project Management UnitPV PhotovoltaicQA/QC Quality Assurance and Quality ControlRDT Rotary Drum ThickenersRFI Request for ProposalRFTOP Request for Task Order ProposalRFQ Request for Qualification (Prequalification Document)RSS Royal Scientific Society, Amman JordanSBR Sequencing Batch ReactorSCADA Supervisory Control Data AcquisitionSRT Solids Retention TimeTRG Training Resources Group USAID United States Agency for International DevelopmentUSD or US$ United States DollarsVFA Volatile Fatty AcidVFD Variable Frequency DriverW&C White and CaseWAJ Water Authority of JordanWTP Water Treatment PlantWWTP Wastewater Treatment PlantYWC Yarmouk Water Company


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Biological and Chemical AbbreviationsATAD Autothermal Thermophilic Aerobic DigestionBNR Biological Nutrient RemovalBOD5 5-Day Biochemical Oxygen DemandCBOD5 5-Day Carbonaceous Biochemical Oxygen DemandCH4 Methane CO2 Carbon DioxideCOD Chemical Oxygen DemandDO Dissolved OxygenEBPR Enhanced Biological Phosphorus RemovalFe IronFOG Fats, Oils and GreaseH2S Hydrogen SulfideHDPE High-Density PolyethyleneNH3-N Ammonia as NitrogenNO3 NitrateNO3-N Nitrate as NitrogenPAO Phosphate Accumulating OrganismPO4-P Phosphate as PhosphorusPVC Polyvinyl ChlorideRAS Return Activated SludgeSVI Sludge Volume IndexSWD Side Water DepthTDS Total Dissolved SolidsTKN Total Kjeldahl NitrogenTN Total Nitrogen TP Total PhosphorusTSS Total Suspended SolidsUV Ultraviolet LightVS Volatile SolidVSR Volatile Solids ReductionWAS Waste Activated SludgeWWTP Wastewater Treatment Plant


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List of Units°C Degree Celsiuscm Centimeterd DayDunum 1,000 Square MetersEggs/l Eggs per Literh Hourh/d Hour per day ha Hectare (10,000 square meters)JD Jordanian Dinarkg O2/kWh Kilograms of Oxygen per Kilowatt-Hourkg Kilogramkg/d Kilogram per daykm Kilometerkm/d Kilometer per daykPa Kilo PascalkV KilovoltkVA Kilovolt AmperekW KilowattkWh Kilowatt-Hoursl Literl/min liter per Minutel/s Liter per Secondlpcd Liter per Capita per Daym Meterm/s Meter per Secondm2 Square Meterm3 Cubic Meterm3/d Cubic Meter per Daym3/h Cubic Meter per Hourm3/min Cubic Meter per Minutem3/s Cubic Meter per SecondMCM Million Cubic MetersMCM/y Million Cubic Meters per Yearmg Milligrammin MinuteMl/d Megaliters per Daymg/l milligram per litermm Millimeter


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MPN/100 ml Most Probable Number per 100 mlPa Pascalppm Parts per Millions Secondy Year

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Executive Summary

Under Task 4 expansion of the Madaba Wastewater Treatment Plant (WWTP) of the USAID Jordan Water Infrastructure project, CDM Smith has been contracted to prepare a feasibility study, design, and tender documents for the plant expansion. This Madaba WWTP Feasibility Study Report fulfills most of the requirements listed in the Task Order Section C, Clauses 4.4 and 4.10.3, Feasibility Studies and Environmental Impact Assessments. The Madaba WWTP condition assessment report was submitted in March 2019 (and resubmitted in August 2019), while the Environmental Impact Assessments will be prepared after wastewater treatment process alternative selection.

This Feasibility Study Report evaluates wastewater treatment processes for the expansion of the existing Madaba WWTP from the current average annual daily 5-day biochemical oxygen demand (BOD5) loading of 7,220 kilograms per day (kg/d) and average annual daily flow (AADF) of 7,600 cubic meters per day (m3/d). The WWTP would be expanded to have an average daily loading capacity of 13,010 kg/d as BOD5 and hydraulic capacity of 16,000 m3/d (16,400 m3/d including septage that is expected to decrease over time as the sewer network is expanded) for the project design horizon date of 2045. In addition to the liquid-stream and solid-stream wastewater treatment processes evaluation, this report also reviews options for unit processes and equipment and makes recommendations based on the Madaba WWTP site requirements.

The objective of this study is to identify wastewater treatment alternatives for the expansion of the Madaba WWTP and recommend the most suitable alternative for design. The draft version of this report was submitted for review on June 30, 2020. This final version incorporates comments received from USAID and the Ministry of Water and Irrigation (MWI) and Water Authority of Jordan (WAJ), including direction from MWI/WAJ for the preferred wastewater treatment alternative selected by the Madaba WWTP expansion Technical Committee staff from WAJ and Jordan Water Company – Miyahuna (MWC).

ES 1 Background The Madaba WWTP is located 5 kilometers (km) south of Madaba City. The original plant was a lagoon-based treatment system built in the 1980s. The plant was expanded and updated, starting in 2000, to an extended aeration activated sludge treatment system that became fully operational in 2002 (referred to herein as the 2002 Plant Expansion).

The 2002 Plant Expansion and upgraded the WWTP to have a biological loading capacity of 7,220 kg/d as BOD5 and hydraulic capacity of 7,600 m3/d secondary treatment configured as a biological nutrient removal (BNR) process to achieve organic matter, nitrogen, and phosphorus removal, with secondary clarifiers (settling tanks). Additionally, new plant inlet headworks and sludge handling systems (thickener and drying beds) were added. The design year for this expansion was 2010 according to the design report.

During the summer of 2016, the summer period average daily influent flow equaled the existing WWTP design capacity. In 2018, the annual average daily (AAD) flow to the WWTP matched the WWTP’s average annual daily flow design capacity. Since 2018, the Madaba WWTP has been operating at the design hydraulic capacity, but the WWTP remains within the design organic loading capacity estimated at less than 6,000 kg/d. The WWTP is aging and the

ES Executive Summary

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WWTP does not operate as efficiently as it should and is in need of an upgrade and expansion to meet the near future needs of the Madaba area.

ES 1.1 Existing ConditionsThe plant receives wastewater from the Madaba City sewer collection network as well as trucked septage from the city and surrounding area. In 2018, the estimated average month influent flow was 7,530 m3/d and the average flow for July 2018 was 8,074 m3/d; August typically has the high annual flows but, because of equipment breakdown, the average flow for August 2018 is unreliable. The existing plant’s design hydraulic capacity is average dry weather flow of 7,600 m3/d and, although the plant is currently operating at the design hydraulic capacity, it is operating at below the design organic loading capacity.

The influent 5-day carbonaceous biochemical oxygen demand (CBOD5) measured during the sampling program in October–November 2018 averaged 768 milligrams per liter (mg/l), which was lower than the design average influent CBOD5 of 950 mg/l. The settling tank effluent CBOD5 averaged 31 mg/l during the sampling, and a CBOD5 removal efficiency of 96 percent was achieved. Total suspended solids (TSS) measured in the influent during the same period averaged 644 mg/l, which was lower than the design average influent for TSS of 1,000 mg/l; although there appears to have been a laboratory testing irregularity on the TSS analysis. The settling tank effluent TSS averaged 57 mg/l during the sampling, well above the design criteria of 30 mg/l.

The plant effluent is not meeting effluent discharge standards for irrigation of cooked vegetables (Category 3A) Jordanian Standard (JS) JS893/2006 for TSS because the plant effluent is not chlorinated sufficiently to kill E. coli. Additionally, effluent storage on-site in the old ponds grow algae that further increases the TSS of the effluent.

ES 1.2 Prior StudiesPrior to completing this feasibility study report, the Ministry of Water and Irrigation (MWI)/ Water Authority of Jordan (WAJ) requested that USAID Jordan Water Infrastructure conduct additional reviews and studies related to the Madaba and the South Amman WWTPs, which delayed the completion of this feasibility study report for the expansion of the Madaba WWTP. The additional studies are:

Evaluation of Madaba Pump Station and Force Main to South Amman WWTP Design by Arab Dar Engineering Company, February 2019; included in Appendix B

Pumping Madaba Wastewater to South Amman WWTP Options Memorandum, July 2019; included in Appendix B

Scoping of combined Madaba and South Amman WWTP effluent reuse options, November 2019; submitted separately in 2019

South Amman Area Effluent Reuse, May 2020; included in Appendix A

These studies were in addition to the Madaba WWTP condition assessment report submitted prior, and the Madaba WWTP Biosolids and Effluent Reuse Study included in Appendix A envisioned in the original 2018 USAID Jordan Water Infrastructure scope of work.


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ES 2 Wastewater Treatment Plant ExpansionThe wastewater treatment alternatives and construction estimates were provided to the MWI/WAJ to assess the different options and make a final decision for the expansion of the Madaba WWTP.

ES 2.1 Wastewater Flows and Loads Projections The projected WWTP influent wastewater flows and loads for the project design horizon of 2045 is 16,000 m3/d average annual daily flow (AADF) and organic loading of 13,010 kg/ as BOD5. The flow projection was identified through analysis and consultation with MWI/WAJ, which is discussed in Section 2 of this report.

The wastewater influent concentration is anticipated to remain similar to the current values through the project design horizon. The influent wastewater concentrations are very high by North American and Western Europe values, but are on par for Jordan; see Section 2 for more parameters.

ES 2.2 Effluent and Biosolids Standards The WWTP effluent standard is per JS893/2006 category 3(A) for effluent reuse of the irrigation of cooked vegetables, as discussed in Section 3. WWTP biosolids (sludge) complies with JS1145/2016 Treated Sludge and Sludge disposal as third-class biosolids for landfill only. Options for the reuse of WWTP biosolids were investigated but Jordanian regulation reuse of WWTP biosolids is very restrictive and no suitable reuse options for biosolids are available.

ES 2.3 Wastewater Treatment Alternatives This study evaluated several liquid-stream wastewater treatment processes and solid-stream (sludge) treatment processes and short-listed seven liquid/solid-stream wastewater treatment alternatives for evaluation. The combinations are:

Alternative A.1 Modify Existing Tanks to plug-flow BNR (five-stage Bardenpho with plug flow) with Primary Clarifiers and Conventional Anaerobic Digestion with combined heat and power (CHP) system for electricity generation from biogas

Alternative B.1 BNR Oxidation Ditch (five-stage Bardenpho) with Primary Clarifiers and Conventional Anaerobic Digestion with CHP system for electricity generation from biogas

Alternative B.1A BNR Oxidation Ditch (five-stage Bardenpho) with Primary Clarifiers and Conventional Anaerobic Digestion with the option for future CHP system for electricity generation from biogas (new alternative addition)

Alternative C.1 plug-flow BNR (five-stage Bardenpho with plug flow) with Primary Clarifiers and Conventional Anaerobic Digestion with CHP system for electricity generation from biogas

Alternative C.1A plug-flow BNR (five-stage Bardenpho with plug flow) with Primary Clarifiers and Conventional Anaerobic Digestion with the option for future CHP system for electricity generation from biogas

Alternative C.2 plug-flow BNR (five-stage Bardenpho with plug flow) with Primary Clarifiers and Covered In-Ground Anaerobic Reactor


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Alternative C.3 plug-flow BNR (five-stage Bardenpho) Primary Clarifiers with aerated sludge holding tank

Alternative E plug-flow BNR (five-stage Bardenpho with plug flow) without Primary Clarifiers

All the alternatives include sludge (biosolids) thickening and two methods for sludge dewatering, mechanical dewatering, and drying beds.

The maintainability and cost-effective evaluation used to score the alternatives identified Alternative C.2 as the most maintainable and cost-effective alternative, while the alternatives with biogas production to generate electricity (A.1, B.1, and C.1) were scored as the least maintainable and cost-effective alternatives. However, solids treatment Alternative 2, Covered In-Ground Anaerobic Reactor (CIGAR), is unfamiliar technology to MWI/WAJ.

MWI/WAJ have expressed a strong preference for WWTP expansion that includes conventional anaerobic digestion with CHP system for electricity generation from biogas to help offset the high cost of plant operations, in which case Alternative B.1 scored highest of the three in the maintainable and cost-effective evaluation (the differences between Alternatives B.1 and C.1 are small enough to be considered the same in the accuracy of this analysis). MWI/WAJ are aware of the operational complexity of these systems and the need for highly trained and qualified WWTP operators to maintain the anaerobic digestion and CHP systems.

The construction and operation cost of the CHP system is high, and it may take several years of WWTP operation before the anaerobic digesters are producing enough gas before seeing operational cost recovery of the CHP system. Therefore, Alternatives B.1A and C.1A are options to reduce the initial capital cost of the WWTP expansion by postponing the installation of the CHP system for a few years into the future.

Conceptual Stage Opinion of Probable Construction CostThe conceptual level opinion of probable construction cost (OPCC) is intended for alternative comparison purposes and includes a contingency to address uncertainties in the conceptual level design and is included for facility owner project budgeting purposes. Following the submission of the draft version of this report CDM Smith conducted an audit of the cost estimate database of the Jordan rates and prices and adjusted the rates and prices to be more appropriate of a project of this size and complexity in Jordan. An updated conceptual stage OPCC was presented to MWI/WAJ during the meeting on December 30, 2020 with a 25 percent contingency for uncertainties in the conceptual level design. The updated OPCCs are included in Appendix C and the December 30, 2020 minutes of meeting are included in Appendix J.

Tables in Section 8 Evaluation of Treatment Alternatives have been updated to include the December 2020 updates conceptual level construction costs estimate (specifically tables 8-4, 8-6, 8-8, 8-10, 8-12, 8-14, and 8-16). However, the analysis of Section 7 Financial and Economic Analysis was not updated since the draft version because this was a comparative analysis and redoing the analysis would not change the cost differences and resulting conclusions.


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ES 2.4 Selected Alternative ES 2.4.1 Engagement with the Madaba WWTP Technical Committee Following the submission of the draft report in early July 2020 several meetings were conducted with MWI/WAJ, MWC, the Madaba WWTP Technical Committee and USAID where the context of the report explained and the treatment alternatives were discussed. The meeting with presentation were held on the following dates:

July 21, 2020, Madaba WWTP expansion feasibility study introduction presentation with MWI/WAJ

August 5, 2020, Madaba WWTP expansion feasibility study introduction presentation for the Madaba WWTP Technical Committee

September 9, 2020, Third Madaba WWTP expansion feasibility study introduction presentation

December 30, 2020, Madaba WWTP expansion feasibility study report alternative discussion and decision. This is when the Madaba WWTP Technical Committee informed CDM Smith of their treatment alternative selection.

January 11, 2021 a site visit to the Madaba WWTP was conducted with the Madaba WWTP Technical Committee

The minutes of meeting for each of the above meetings and presentations are included in Appendix J.

The selection made by the Madaba WWTP Technical Committee on December 30, 2020 was formalized in a letter from MWI/WAJ dated January 21, 2021 with the following statement:

“1. The technical committee recommends alternative "C1.A", which is the BNR (plug flow) system with Primary Clarifiers and Conventional Anaerobic Digestion.”

This letter included many comments from the Madaba WWTP Technical Committee, and responses to each of the comments was prepared by CDM Smith and submitted to MWI/WAJ in a letter dated February 18, 2021 included in Appendix J. The comments and the designer’s responses are presented in Table ES-1.

Table ES-1 Madaba WWTP Technical Committee Comments and Responses

No. Technical Committee Comments Designer Responses

1 The technical committee recommends alternative "C1.A", which is the BNR (plug flow) system with Primary Clarifiers and Conventional Anaerobic Digestion.

The basis of design report and the detailed design will be developed per this selection.

2 The new aeration tanks located above buried solids sludge with approximate thickness of 4mm (should be 4m), the cost to transport this sludge to Al-Akaider (if allowable) will be very high, so the technical committee recommend to transport and bury the sludge to the southern site of the treatment plant behind the main road.

In the BODR we will evaluate what needs to be done to address the old sludge as requested. The geotechnical investigation should identify the limits and depth of the sludge layer. Additionally, we will ask RSS to sample the old sludge so that the suitable containment can be designed for the old sludge.


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No. Technical Committee Comments Designer Responses

3 The technical committee has a concern about the water comes from (septage hauling) trucks that have a lot of grits, the committee asked CDM to add a grit removal in addition to the screen (headwork).

Good point. In the BODR we will identify suitable septage flow grit removal technology. Package systems are available for this purpose.

4 All gates shall be motorized, local, and manual. In addition, the sludge gate to be telescoping gate.

All gates/valves used to adjust process flow or control start/stop of process equipment will be motorized and will have local control at the gate/valve via the electric actuator in addition to the manual operator and the SCADA automatic control. Gates and valves that don’t require frequent position adjustment but are occasionally moved for maintenance of equipment or diverting/isolating flow during infrequent events, does not have to be motorized and will not require electric actuators, it will be manually operated at the valve/gate.Telescoping valve/gate will be used where appropriate.

5 Shall add to the effluent storage pond a diversion chamber to the existing polishing ponds for more extra storage in case a lot of excess flow and the farmers didn't use the treated water and reuse effluent to the irrigation pond.

We will make every effort to use as much of the existing pond capacity for effluent storage as possible while not interrupting operations of the existing WWTP during construction of the expansion.

6 To be sure that the size of the headwork channels and the pumps calculated at the peak flow.

This headworks design hydraulic capacity is intended for the peak flow (2.5 times average annual flow which is 40,000 m3/d). An influent pump station is not necessary at Madaba WWTP, but all process pumps will be designed for the peak flow/load operation conditions.

7 As the expansion located at the wadi, CDM has to make geotechnical investigation and has to consider the wadi flooding and to suggest the proper protection for the new treatment plant like retaining wall or Gabions, etc.…

The site geotechnical investigation started in January 2021 and the design will consider issues with the adjacent wadi. In addition, the new facilities of the expansion will be a little off the Wadi route, but the protection is still needed.

8 'Maintenance of the Diffusers shall be taken into consideration so it can be easily maintained without emptying the tanks.

While there are some retrievable aeration systems available on the market, they are only applicable to very small treatment plants. For Madaba, the cost to provide this capability would be prohibitive. The fine bubble diffusers will need to be attached to the floor of the aeration basin and the basin will need to be drained to perform maintenance. The redundancy provided allows one train to be taken offline during off-peak periods.

9 Specify the type of WWTP boundary, either wall or fence.

Our assumption is the boundary fence would be chain-link fence because this is the lowest cost option, but this can be changed to what WAJ and MWC believes is the most suitable type of fence for the site. The options are:A) chain-link fence; B) masonry wall; C) 1m high masonry wall with chain-link fence on top; or D) a combination of A, B and/or C.

10 Replace the clamshell bucket to clean out the rock trap with a removal basket.

A removal basket in the rock trap is not recommended for the following reasons:1) When the basket is pulled out for emptying, gravel and rock will fall to the bottom of the chamber and it will make it impossible to fully re-insert the basket and then what happen most often is the basket is left out and not used. Our WWTP operations specialist does not recommended the basket for the reason given.2) To handle the volume of gravel and rock that my come down the sewer during a storm (based on East Jerash WWTP experience) that basket would need to be large and once full


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No. Technical Committee Comments Designer Responsesof gravel and rock will be very heavy and need a big crane to lift out the basket.

11 Regarding the primary sludge pumps, could CDM check the velocity and the slope to collect the sludge from the four tanks into one chamber then pump it to the screens above the thickener to minimize the numbers of pumps from 16 to 3 pumps.

We understand your concern about the high number of pumps and will do what we can to reduce the amount of equipment. However, the hydraulics of primary sludge is different from clean water and it does not flow as well so pumps are necessary to maintain effective process control and provide sufficient back-pressure for the sludge screens to operate.

12 To conduct rehabilitation/replacement for the electro-mechanical equipment in the existing aeration tanks (as an optional choice).

This is WAJ's choice. However, we do not recommend replacement/rehabilitation of all the electrical-mechanical equipment unless there is a specific plan on how and when this system would be used.We are considering a plan for using the existing aeration tanks as part of the "influent combined sewage" management system. This is influent flow in excess to the WWTP's peak flow capacity (40,000 m3/d) would be diverted through the existing headworks and to the existing aeration tanks for temporary storage. Then the stored water would be pumped back to the influent of the new WWTP for treatment after the storm passes. When the existing aeration tanks are full, it will overflow to the existing equalization ponds.

13 To add main irrigation line with risers (for the current and future agreements).

Assume this is referring to the pumping of treated effluent to the nearby farmers. This can be accommodated but WAJ needs to provide the estimate for the future flows.

14 Make a connection between the current and the new influent.

The new tie-in chamber forms a connection between the new and old influent. However, we need to understand WAJ's intent for this connection. Is it to be able to direct flow to either the new WWTP or to the old WWTP? Please provide clarification.

15 When we need to empty any pond, whether treated or not, to determine this quantity and the place you where it will be disposed of.

We understand this to be a request for an operations plan and related infrastructure so any of the ponds can be easily emptied after the WWTP is expanded. The BODR will outline these requirements.

16 To review the high capital and running cost estimate.

As stated in the feasibility study report, the cost is based on a conceptual level of design and have inherent error, so a contingency is included to account for the error.However, the BODR will update and evaluate the capital cost and operational costs for the selected alternative.

17 What about spare parts? The technical specification includes standard recommended spare parts for the equipment which is often based on the manufacturer's recommendations. In some cases, we require additional items based on experience as good items to have. The construction contractor may use the spare parts during the operation period but has to restore the spare parts store upon handover back to MWI/WAJ.What is Jordan Water Company-Miyahuna (MWC) and WAJ's requirements for WWTP spare parts?

The preliminary design of the Madaba WWTP expansion will proceed according the above Technical Committee comments and its corresponding designer response, unless directed otherwise in writing by MWI/WAJ within a reasonable amount of time. As of April 7, 2021, no comments (in writing or verbal) to the responses in Table ES-1.

Cautionary NoteAs mentioned prior, modern wastewater treatment plants are complex facilities to design, construct and operate and conventional anaerobic digestion and CHP systems for electric


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power generation are the most complex and expensive to operate and maintain at any WWTP. They involve complex biological processes and require highly trained operators that know the processes and can troubleshoot biological process and mechanical problems. In addition, struvite formation potential in the anaerobic digesters would exist at this new facility and can create further challenges. Struvite mitigation may require additional chemical, thus increasing the operation and maintenance (O&M) costs.

The decision by MWI/WAJ and the Madaba WWTP Technical Committee to not include the CHP systems for electricity generation now but allow for the option to add it in the future is a reasonable decision to save costs and will give MWI/WAJ the opportunity to gain more experience at operating modern WWTPs without the additional complexity and costs of the CHP systems. Additionally, alternative uses for the digester biogas such as making hot water to sell for industrial use.

Additionally, this facility will incorporate a high degree of instruction and complex electronics that require specialized instrumentation, automation, and integration engineers to construct and maintain. Although the designer is making reasonable effort to minimize the facility complexity, the complexity is mainly governed by the biological process control requirements and current available wastewater treatment equipment technology, which is highly dependent on instrumentation and electronics.

ES 4.1.2 Design Strategies to Mitigate the WWTP Operational ComplexityThe above cautionary note is a warning on the technical and operational complexity of modern water treatment facilities. Table ES-2 presents some practical measures that can be implemented during design to help mitigate some of the operational complexities.

Table ES-2 Strategies to Mitigate WWTP Operational Complexity

ID Strategy Comments/Method/Benefit

1 Process equipment system supplied by a single vender

Sole-source responsibility for assembling and integrating all the components of a system to ensure that they all work together and function as intendedThe P&ID drawings will show equipment packages to be supplied by a single vender to clearly delineate system responsibility.

2 Long-term service contract with the automation/ instrumentation (SCADA) system integration contractor.

The remote access to the WWTP SCADA system planned for this WWTP will enable an offsite instrumentation integration contractor to monitor the WWTP functions and, in most cases, resolve issues remotely or make recommendations to operations staff to resolve issues without requiring a site visit.

3 Listing of acceptable equipment manufacturers in the specifications

This increases the likelihood that the construction contractors will select suitable process equipment during the bidding phase. This will facilitate submittal review during contracting and reduce the risk of inappropriate equipment installation that would result in poor performance, more maintenance, and higher operation costs.

4 Upgrade waste activated sludge thickening from belt thickeners to the dissolved air flotation (DAF) process.

Belt thickeners cannot operate 24 hours per day. This results in additional complexity for the sludge wasting system, including larger WAS pumps and thickened WAS storage with mixing pumps and additional feed and discharge pumps. Dissolved Air Flotation (DAF) operates 24 hours per day, allowing continuous wasting and eliminating the need for additional sludge storage, mixing, and pumping. DAF is also less complex to operate.

It is important to point out that although the above strategies will help to reduce the overall WWTP operational complexity and result in long-term lower O&M costs, some of them may have an initial higher capital cost that would impact the construction bid prices.


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ES 4.1.3 Selected Alternative Conceptual Stage Opinion of Probable Construction Cost

ES 4.1.4 Selected Alternative Estimated Operation and Maintenance Costs


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The energy costs presented in above Table ES-4 appear high compared to existing electricity bills for the Madaba WWTP. Conceptual design phase studies are subject to inaccuracy due to the conceptual nature of the study, additionally the following factors could also help explain the differences. They are:

Currently published electrical rates for WWTP are used and include annual escalationincrease in the rates,

Typical power consumption rates for wastewater processes are used that can bedifferent for specific site conditions, and

The existing WWTP is operating the aeration equipment at lower than optimum rates asindicted by the depressed dissolved oxygen levels in the aeration tanks identified by thecondition assessment study conducted in 2018.

To estimate the cost of the construction contractor’s O&M period following the completion of construction is derived from the conceptual study rates presented above in Table ES-4. The assumptions made to estimate this cost are as follows:

Most consumable would be paid directly by MWI/WAJ to avoid the cost markup thatwould be applied if the construction contractor paid these costs directly. This includeselectricity, process chemicals (chlorine gas, polymer, and ferric chloride), solids haulingto landfill, fuel for the standby generator and digester waste gas flare pilot light.

The construction contractor would pay directly for labor and general andadministrative costs, including chemical and materials for the plant water qualitylaboratory, off site water analysis by third parity laboratory. Additionally, it wasassumed that the contractor would apply a 15 percent markup for his overhead andprofit.


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Repair and replacement costs is long-term to maintain that required by equipment atthe WWTP during the contractor’s O&M period the equipment is new there is no costincluded for the contractor’s O&M period.

The opinion of probable cost for the contractor’s O&M period with 2 years of operation plus and optional third year are presented in Table ES-5. Implementation of the third year of operation is at the choice of MWI/WAJ. The rates in above Table ES-3 came from this table.

Table ES-5 Opinion of Probable Contractor’s 3-year O&M Costs (US$1000)

This opinion of probable cost for the contractor’s O&M period is only an estimate for the conceptual study and will change in accordance with MWI/WAJ and MWC requirements and the conditions of the construction contract.

ES 2.4.5 Effluent ReuseThe WWTP treated effluent reuse options are evaluated in Section 6 and three options discussed for reuse of treated effluent for the irrigation of crops. Since the draft report was submitted the new USAID Jordan Water Engineering Services (WES) project has been tasked with studying opportunities for regional effluent reuse from South Amman WWTP as well as from the Madaba WWTP. It will take time to identify, evaluate and implement a regional effluent reuse scheme. Therefore, the design of the Madaba WWTP expansion will proceed with Effluent Reuse Option I – Status Quo as outlined below.

Treated effluent reuse storage pond with a target volume of 32,000 m2 of storage (2days at design average flow) and lined with HDPE lining and HDPE floating tile cover toprotect water quality by controlling algae growth and evaporation.

New local (irrigation) effluent reuse pump station to continue to supply water to thefarmers currently receiving with the capacity to add new connection as the supplyallows.

Provide provision for the connection of a future pump station identified through theUSAID WES study. The design of this pump station is not within USAID Jordan WaterInfrastructure project scope of work.

To the extent possible, the existing pond on site will be utilized to store overflow fromthe main treated effluent reuse storage pond. However, to keep costs down the overflowponds will not be lined or covered and receive minimum modification.

ES 2.4.6 Summary of WWTP Expansion FacilitiesThe facilities of the new WWTP expansion are detailed in the following sections of this report and are summarized in the following three tables as follows:


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Table ES-6 WWTP Expansion Facilities – Liquid Stream. The main flow streamthrough the WWTP from the plant influent through to the treated effluent discharge.

Table ES-7 WWTP Expansion Facilities – Solids Stream. The side stream thathandles and process the solids (primary sludge and waste activated sludge) removedfrom the liquid stream.

Table ES-8 WWTP Expansion Facilities – Supporting Facilities. WWTP non-processfacilities that are necessary to the function of the WWP.

Table ES-6 WWTP Expansion Facilities – Liquid Steam

ID Facility Description

1 Tie-In and Influent Combined Sewage (ICS) Diversion Chamber (new structure)

The WWTP expansion connection to the existing influent sewer pipes with facility to divert high sewage flow combined with rainwater to temporary storage.

2 Influent Combined Sewage (ICS) Management System (new and rehabilitation of existing)

Influent flow in excess of the WWTP expansion peak design flow (40,000 m3/d) is diverted at the ICS Diversion Chamber (ID 1 above) through screens to remove trash and then stored in the ICS Ponds (rehabilitation of the existing equalization basins). After the storm passes and influent flow returns to normal, the water in the ICS pond is pumped back to the headworks for treatment.

3 Septage Unloading Station (new structure)

New facility for unloading of tanker trucks hauling septage. The unloaded septage is checked for pH that may indicate toxins and goes throughs grit removal and pumped to the anaerobic digester system.

4 Rock Trap (new structure) Use during the wet season to collect gravel and rocks conveyed to the WWTP through the collection network. This is a bypass pipe to bypass the Rock Trap during the dry season when it is not needed.

5 Headworks (new structure) Sized for the expansion capacity with trash rack, mechanical multi-rake type screens, aerated grit and grease removal system and influent flow measurement.

6 Headworks Odor Control (new structure) To reduce objective odors in areas known to have a high level of odors.

7 Primary Clarifiers (new structure) Four circular primary clarifiers, primary sludge pumping, and scum handling

8 BNR tanks and blower building (new structure)

Four parallel Bardenpho with plug flow BNR tanks (changed to linear configuration from serpentine shown in this study), with submerged fine bubble diffusers

9 Secondary Clarifiers (new structure) Four circular secondary clarifiers with RAS and WAS pump stations and scum management

10 Chlorine contact tank (new structure) Treated effluent disinfection with chlorine gas and include the chlorine building with dosing control and chlorine cylinder storage

11 Effluent Reuse Storage Pond (rehabilitate of existing)

One pond with 32,000 m3 capacity with HDPE liner and floating tile cover. Outlet to effluent reuse pump station, and overflow to existing ponds on site

12 Local (irrigation) Effluent Reuse Pump Station (new structure)

Pump station with efficient vertical turbine pumps with discharge manifold where nearby farms can attach their pipes too. Maximum pumping capacity is equal to average daily flow plus 20 percent 19,200 m3/d.

13 Future Regional Effluent Reuse Pump Station (future by others)

Include provision for the connection of a future effluent reuse pump station to be designed by others.

14 Effluent overflow ponds (existing, minimum rehabilitation)

Effluent overflow from the effluent reuse storage pond flows to on site existing ponds for storage (as hydraulic grades


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ID Facility Descriptionallows) for additional storage. These ponds are not lined or covered and will receive minimum modifications.

15 Existing irrigation pump station (existing, minimum rehabilitation)

Effluent in the overflow ponds flows into the existing irrigation pump station for pumping to farmers.

16 Emergency Overflow to Wadi (existing) The existing irrigation pump station as an overflow to an existing outfall leading to the wadi. When the overflow ponds become too full, they will overflow though the “emergency” overflow to wadi.

The WWTP solids stream or side stream processes include.

Table ES-7 WWTP Expansion Facilities – Solids Steam


1 Primary Sludge Gravity Thickener Tanks (new structure)

Reduces primary sludge and septage volume by removing excess water that is recycled to the liquid stream for treatment. Reducing the sludge volume reduces the size of the anaerobic digesters and associated equipment.

2 WAS Gravity Belt Thickeners (GBT) (new structure)

Reduces WAS sludge volume by removing excess water that is recycled to the liquid stream for treatment. Reducing the sludge volume reduces the size of the anaerobic digesters and associated equipment. WAS does not thicken well in gravity thickener tanks so the GBT are used because it is known technology in Jordan. However, DAF is a good alternative with lower costs and easer operations.

3 Anaerobic Digester System (new structure)

Conventional anaerobic sludge digestion for reducing and stabilizing sludge and a byproduct produced by the process is digester gas (methane). The digester tanks are headed to 35°C through hot water heat exchangers and a boiler that operates on digester gas or diesel fuel.

4 Digester Gas Management (new structure)

Digester gas is explosive and a powerful greenhouse gas so it must be contained and handled with care. Piping will convey the gas produced in the digesters to fuel hot water boiler and excess gas is burned in the waste gas flare. Since the CHP system is not included in this stage there is no gas storage provided, but an area is identified for future gas storage if a CHP system is added in the future.

5 Drying Beds (new structures and rehabilitation of existing)

Sludge drying beds are the primary method for digested sludge dewatering and drying up to 50 per solids content. However, the drying bed performance is very poor during the cool and wet winter months, and mechanical dewater is provided to supplement the drying beds during this period.New decant type sludge drying beds are required as existing beds require rehabilitation. Some of the drying beds may require covers to prevent the rain from rewetting the drying sludge.

6 Mechanical Dewatering (new structure, reusing existing equipment)

To supplement the drying beds during the winter mechanical dewatering is provided with two sludge screw presses for initial sludge dewatering. Polymer is necessary and this requirement is reflected in the above chemical costs.The existing sludge screw press at Madaba WWTP will be repaired and used in this new facility.

7 Sludge Management Equipment (new) Wheeled equipment for moving and loading sludge and other solids no to trucks for hauling off-site, and equipment for turning sludge in drying beds to accelerate drying.


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Table ES-8 WWTP Expansion Facilities – Supporting Facilities


1 Administration Building (new structure) New plant administration building with the Control Room and SCADA server room, offices, meeting room, plant water laboratory, and bathrooms.

2 Maintenance Building (new structure) New building with secure areas for storage materials and equipment, conducting basic maintenance, and facilities for the plant operation staff.

3 Guard House at Septage Unloading Station (new structure)

A small guard room for the plant attendant of the septage trunk unloading station and a water closet for use by the septage truck crews.

4 Electrical Transformer (new structure) The electrical utility service requires upgrading and a fenced in pad area is provided for the new utility transformer. The existing transformer will remain for the existing WWTP.

5 Main Electrical Building (new structure) House the plant electrical distribution panels and gear and the new plant standby generators rated to power the whole WWTP.

6 Headworks Electrical Room (new structure)

Contains variable frequency drives (VFD) and electronic-soft starters for motors in the headworks and primary clarifier areas. The electrical rooms air condition and filtered to protect the electronics.

7 Blower Building (new structure) Contains the blowers for the BNR tank aeration system and an electrical room for the panels and starters for the blower motors and other nearby motors. The electrical rooms air condition and filtered to protect the electronics.

8 Chlorination Building (new structure) Chlorine gas container storage and effluent disinfection chemical dosing and monitoring equipment.

9 Digester Complex (new structure) The building that contains most of the anaerobic digester equipment including the hot water system boiler, pumps and other system equipment. Additionally, there is a small control room and electrical room.

10 Solids Handling/Screw Press Building (new structure)

Contains the mechanical sludge dewatering screw presses, polymer chemical storage and mixing equipment, and electrical room

11 Plant wide Supervisory Control Data Acquisition (SCADA) Network

WWTP wide SCADA with server and main interface located in the Administration Building. Also include is access to the plan SCADA on a mobile device (i.e., tablet) around the plant site and from off site through the internet.

12 Disposal for old sludge Old sludge that was buried on site in the past need to be removed for the construction of the new BNR tank. As instructed by MWI/WAJ this material will be relocated to available land at the southern end of the WWTP site.

13 WWTP Boundary Fence Most of the existing boundary fencing requires replacement. New fencing or wall options for better site security will be evaluated.

ES 3 Next StepsWork on the preliminary design for the Madaba WWTP expansion started in mid-January 2021 based on the Madaba WWTP Expansion Technical Committee discission on December 30, 2020 that was confirmed in the MWI/WAJ letter dated January 21, 2021. The next steps for this design project are:

Prepare the Preliminary Design – Basis of Design Report (BODR), which advances the selected treatment alternative to about the 30 present design. – By CDM Smith


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Review of the Preliminary Design – BODR by MWI/WAJ, MWC, the Madaba WWTPExpansion Technical Committee and USAID. After submission of the report thefollowing meetings will be scheduled:

A presentation meeting to introduce the Preliminary Design – BODR for MWI/WAJ,MWC, the Technical Committee, USAID and other stakeholders.

Workshop with MWI/WAJ the Technical Committee and stakeholders to review andreceive comments on the preliminary design.

MWI/WAJ issues letter with comments on the Preliminary Design – BODR andacceptance of the report. – By MWI/WAJ

Proceed with detailed and final design of the Madaba WWTP expansion by CDM Smithand local engineering subcontractor.

Workshop to update MWI/WAJ the Technical Committee and stakeholders on theproject design at the 60 percent design stage.

Workshop to update MWI/WAJ the Technical Committee and stakeholders on theproject design at the 90 percent design stage.

Prepare tender documents, conditions of contract and BOQ as required by MWI/WAJand the construction funding agency.

Prepare the Final Design – BODR, which is an update of the Preliminary Design – BODRupdated to incorporate decision made during detailed design. – By CDM Smith

Construction cost estimates. – By CDM Smith

The goal is to complete the final design of the Madaba WWTP expansion by the end of 2021 because the USAID Jordan Water Infrastructure project will be in its last year by then and the design phase of Task 4 must finish up. Therefore, it is critical for MWI/WAJ and the Technical Committee to expedite decision making and minimize changes with respect to the Madaba WWTP expansion.


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Section 1Introduction

1.1 Summary of the USAID Jordan Water InfrastructureCDM International (CDM Smith) was retained by the United States Agency for International Development (USAID) to undertake the USAID Jordan Water Infrastructure (the Project) to improve the utilization of limited water resources in Jordan and bring about urgently needed enhancements to the water and wastewater systems. Water and wastewater infrastructure improvements are needed throughout Jordan to alleviate water supply shortages, public health issues, and impacts on industry and the economy. The Project will serve as an umbrella contract for USAID/Jordan’s water, wastewater, and environment sectors and will cover multiple tasks specifically designed to achieve the paired objectives of delivering needed water infrastructure and capacity building to WAJ and water companies throughout Jordan.

The project covers engineering infrastructure improvements identified by USAID in cooperation with MWI, WAJ, public sector water companies such as Jordan Water Company, Miyahuna, Yarmouk Water Company (YWC), and the Aqaba Water Company (AW), the various municipalities, and the Ministry of Environment (MoE). The program provides engineering services to carryout assessments, studies, and design and construction management for water, wastewater, and environmental projects.

The major components of the Project are summarized as follows:

Task 1 – Aqaba-Amman Water Desalination and Conveyance Project (AAWDCP)

Task 2 – Construction Supervision – Shedeyyeh – Hasa Water Project Phase I

Task 3 – Detailed Engineering Design and Tender Documents for Expansion of Zai Water Treatment Project

Task 4 – Feasibility Study, Design, and Tender Documents for Expansion of Madaba WWTP

Task 5 – Feasibility Study, Design, and Tender Documents for Expansion of Ramtha Wastewater Treatment Plant

Task 6 – Water and Wastewater Project for Dair Alla and Al Karamah, Balqa Governorate

Task 7 – Water and Wastewater Project for Bani Kenanah/Irbid Governorate

Task 8 – Technical Assistance to Water Utilities (optional)

Task 9 – Assessment of Water/Wastewater Systems, Feasibility Studies, Designs, Tendering Support, and Construction Management Services (optional)

Section 1 Introduction

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1.1.1 Scope of the Feasibility StudyExpansion of Madaba WWTP feasibility study requirements are described in the USAID Jordan Water Infrastructure project Task Order, Section C, Clause 4.10.3 Feasibility Studies and Environmental Impact Assessments. Specific items from this section describing the condition assessment scope include:

e. Assess and evaluate the existing systems regarding its conditions, serviceability, and capacity. (Addressed in the Madaba WWTP condition assessment report.)

f. Identify, evaluate, and recommend the need for rehabilitation, upgrading, and expansion of wastewater facilities throughout the design horizon (2045).

g. Identify, evaluate, and recommend alternatives for the rehabilitation, upgrading, and expansion of wastewater facilities and reuse/disposal facilities throughout the design horizon. Assess all the existing treatment plant units to determine the extent of rehabilitation needed. Recommend enhancements and improvements for the rehabilitation and upgrade of the current plants. Identify suitable sites for expansion.

l. Study and evaluate modes of operation of the wastewater facilities improvements. Establish appropriate operation and maintenance procedures.

m. Assess the present arrangement and organization of the water utility for the operation, maintenance and repair of the wastewater facilities in the Project area. List the number and qualifications of personnel, workshop premises, equipment, and vehicles, and their state of repair, type, volume, range, and problems of services being carried out. Recommend improvements to the quality and number of staff and equipment needed to operate the system efficiently. (Addressed in the Madaba WWTP condition assessment report.)

The condition assessment report focused on items “e” and “m” for the Task Order, Section C, Clause 4.10.3 (listed above) and was the basis for preparing this Feasibility Study for the Madaba WWTP expansion and upgrade.

1.1.1.1 General Scope of the ProjectThis feasibility study report examines the expansion requirements for the Madaba WWTP to the project design horizon of 2045, which includes consideration of new areas that may be added to the plant’s catchment area, as identified by MWI/WAJ. Although this report considers new areas of the collection system for wastewater flow projections, the study and design of the new wastewater collection networks is beyond the scope of this project.

Task 4 is limited to the study and design of the expansion of the Madaba WWTP within the existing plant site, including upgrade and or replacement of existing plant infrastructure per the identified requirements needed to comply with JS for effluent and solids disposal. Off-site work is limited and may include replacement of a short section of the raw wastewater main pipe entering the plant (up to 500 m), and a new reuse pipeline to convey treated effluent to end user, as approved by MWI/WAJ and USAID.

The task scope was expanded at the request of MWI/WAJ and approved by USAID as follows:


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Conduct a study on the feasibility of the plan to pump all of Madaba City area wastewater to the South Amman WWTP for treatment. Discussion is included in Appendix B.

Conduct a feasibility study on the pumping of South Amman WWTP treated effluent to the Jordan valley for reuse in agriculture. Discussion is included in Appendix B.

Table 1-1 lists the project stages and deliverables and their current status as defined by USAID Jordan Water Infrastructure.

Table 1-1 Project Stages and Status

ID Project Stage / Deliverable Status

1 Data Collection Completed, including wastewater sampling program conducted in November 2019. Will receive new information as available.

2 Condition Assessment Report Completed. Final submitted in March 2019. New comments were received in July 2019 and updated final report submitted in August 2019.

3 Feasibility Study and Effluent Reuse Study

This report is the draft submission of this deliverable.

4 Environmental Impact Assessment (EIA) Not started5 Geotechnical Investigation Not started. Will start after selection of feasibility study

alternative.6 Preliminary Design

(Basis of Design Report)Not started. Expect to start August 2020 after selection of feasibility study alternative.

7 Detailed Design and Tender Documents Not started. Expect to start October 2020 after preliminary design review.

8 Technical Memorandums As needed.– If WAJ Secures Funding: Not started.9 Assist WAJ in the Precontract Services Not started.10 Act as the Engineer under the contract Not started.

Note: Bold text indicates the current stage of the project.

1.1.2 Report OrganizationThis report is organized into 10 sections and appendices. The report started with background of the Madaba WWTP with a summary of the current wastewater flows and loads in Section 2.

Section 1 – Introduction

Section 2 – Summary of Wastewater Flows and Loads

Section 3 – Treatment Requirements and Effluent Standards

Section 4 – Existing WWTP Condition Assessment Report

Section 5 – The assessment of treatment technologies suitable for this plant expansion that consider several treatment process alternatives for the liquid-stream as well as alternatives for the solids (sludge) stream treatment. Once assessed, identify the criteria used to evaluate the alternatives. The section concludes with discussion on options for support processes at the plant.


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Section 6 – Summary of the effluent and biosolids reuse alternatives identified by the Water and Biosolids Reuse Study included in Appendix A of this report.

Section 7 – Financial and economic analyses of the alternatives identified in Section 5.

Section 8 – Evaluation of liquid and solids stream treatment alternatives identified in Section 5, and reuse alternative identified in Section 6.

Section 9 – Summary of treatment recommendations, engineering design requirements for the recommended treatment alternative, and treatment supporting system to establish the Basis of Design Report (preliminary design).

Section 10 – WWTP Expansion implementation program for the plant expansion.

1.1.3 Flow Terminology This report uses the following terminology and abbreviation to describe flows in the WWTP:

Annual average daily flow (AADF), cubic meters per day (m3/d)

Average day maximum month flow (ADMMF), m3/d

Maximum day flow (MDF), m3/d

Peak hourly flow (PHF), m3/d

Dry weather flow terms and abbreviations:

Average daily dry weather flow (ADDWF), m3/d

Average daily maximum month dry weather flow (ADMMDWF), m3/d

Wastewater influent-loading parameters, such as chemical oxygen demand (COD), BOD5, total suspended solids (TSS), total Kjeldahl nitrogen (TKN), and total phosphorus (TP) terminology and abbreviations:

Annual average daily (AAD) – typically in units of kilograms per day (kg/d)

Average day maximum month (ADMM) – typically in units of kg/d

Maximum day (MD) – typically in units of kg/d

1.2 BackgroundMadaba City is in Madaba Governorate and located about 30 km southwest of Amman City and the Madaba WWTP is located approximately 5 km south of Madaba City center, as shown in Figure 1-1. The original WWTP built in the 1980s was a lagoon-based system. The plant was expanded to 7,600 m3/d AADF, updated to extend the aeration process, and began operating in the 2002 Plant Expansion. Northern Madaba Governorate is adjacent to Amman and experienced urbanization similar to Amman City.


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1.2.1 Plant Location

Figure 1-1Madaba WWTP Location

The Madaba WWTP site has an area of 400,000 square meter (m2) occupied by the current facility, as shown in Figure 1-2. Adjacent to the plant site on the east and south sides, WAJ owns an additional 8,000 m2 parcel for expansion of the WWTP. The existing Madaba WWTP site plan is shown in Figure 1-3, which is the same as Drawing No. G-MA-5. The WWTP effluent is reused for irrigation and discharged to Wadi Al-Habeth.


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Figure 1-2Madaba WWTP Site and Area Available for Expansion

Figure 1-3Existing Madaba WWTP Site Plan


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1.2.2 Plant History and Existing Plant DescriptionThe original Madaba WWTP was a lagoon-based treatment system built in the 1980s. Beginning in the late 1990s, the plant was expanded and updated into an extended aeration system that became operational in the 2002 Plant Expansion. The process flow block diagram is shown in Figure 1-4.

The Madaba WWTP secondary treatment is configured as an A2O BNR process to remove organic matter, nitrogen, and phosphorus. Each of the two identical A2O treatment trains has one anerobic tank, three anoxic tanks, and one aerobic tank. Each aeration tank is equipped with six platform-mounted vertical surface aerators. Each aerator is sized at 45 kilowatts (kW) to provide 1.8 kilograms (kg) of oxygen per kilowatt hour (O2/kWh). The aeration tanks are configured as long and narrow rectangular tanks with six surface aerators installed in series to promote plug flow conditions. The internal recycle pumps are sized to recycle as much as 3 times the average daily flow (Q) nitrified mixed liquor from the end of the aeration tanks to the anoxic tanks for denitrification.

The BNR process has three internal recycle pumps (two duty and one standby), each with 11,400 m3/d capacity. The BNR process is followed by two 22-meter (m) diameter circular clarifiers with a sidewall depth of 5 m, two polishing ponds, two tertiary maturation ponds, two rock filter systems, and a chlorination chamber. The return activated sludge (RAS) is pumped (by return sludge pumps) from the settling tanks (secondary clarifiers) to the anerobic basins by RAS pumps, which can provide RAS flows up to 1Q. The waste activated sludge (WAS) is first pumped (by excess sludge pumps) to a gravity thickener unit. The thickened WAS is then transferred to one of the 156 sludge drying beds at the plant for sludge drying and stabilization before disposal. The 2002 Plant Expansion process block diagram from the existing WWTP O&M manual is presented in Figure 1-4.


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Figure 1-4Existing Madaba WWTP Process Flow Block Diagram

1.2.3 Other Programs at Madaba WWTPTo date, no other projects and programs were identified to be working at the Madaba WWTP.


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1.2.4 Exiting Wastewater Treatment Plant Flows and LoadsThe 2002 Plant Expansion capacity was 7,600 m3/d AADF and BOD5 loading of 7,220 kg/d to serve Madaba City. As of 2018, the Madaba WWTP is operating at 100-percent capacity, as provided by MWI/WAJ and MWC, and shown in the influent flow measurements in Table 1-2.

Table 1-2 Historic Influent Flow Measurements 2015–2018

Influent Monthly Average and Peak Flows (m3/d)

2015 2016 2017 2018MonthAvg.

Month Peak Avg. Month Peak Avg.

Month Peak Avg. Month Peak

January 6,757 670 7,031 600 6,744 570 7,281 756

February 6,516 579 7,144 607 6,638 699 7,756 760

March 6,290 470 6,658 277 6,726 557 6,862 570

April 6,213 560 6,242 470 7,158 516 7,167 575

May 6,907 480 7,616 550 7,132 470 7,825 563

June 6,956 547 7,280 420 7,614 513 7,609 556

July 7,156 570 7,336 520 7,689 550 8,074 660

August 6,623 650 7,608 560 7,878 560 8,311* N/A

September 6,309 540 7,666 590 7,596 516 7,881 N/A

October 6,592 595 7,218 581 7,146 580 7,524 N/A

November 6,033 510 6,525 570 6,630 567 6,994* N/A

December 6,331 430 6,438 650 6,705 560 7,073* N/A

Annual Avg. Monthly 6,557 – 7,064 – 7,138 – 7,530 –

Dry Weather Avg.** 6,757 – 7,454 – 7,508 – 7,871 –

*2018 flows for the months of August, November, and December are estimates based on the ratio between monthly and annual flow in 2017**Dry weather months are May through October

Table 1-3 compares the WWTP design criteria from the 2002 Plant Expansion design report to the results from a two-week-long sampling program conducted by Royal Scientific Society (RSS) under subcontract to CDM Smith between October 28 and November 13, 2018. Findings of this sampling program are in the Madaba WWTP expansion condition assessment report, USAID Jordan Water Infrastructure.


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Table 1-3 Existing Madaba WWTP Design Basis and 2018 Sampling Results

2002 Plant Expansion Design Criteria

Oct/Nov 2018 Sampling Results

Description UnitsRaw

Influent

Settling Tank

Effluent

RawInfluent (Avg.)

Settling Tank

EffluentComments

Target Year (Design Year) year 2010 – – – 8 years past design

horizonPopulation (2017) People 90,420 – – – Wastewater generation =

84 lpcd

Flow: AADF

m3/d 7,600 – 6,985Estimated daily average for sampling period in Oct–Nov 2018

BOD5

mg/l Avg.mg/l Rangekg/day*

950–7,220

20–

768657 – 936

5,367

3119 – 82

220

Raw sampled after septage unloading (MC-2).BOD5 loading at 74 percent design. 12 of 13 samples exceeded effluent limit.

CODmg/l Avg.mg/l Rangekg/day*

1,6601,212 – 2,097

11,593

9559 – 172

664

Raw sampled after septage unloading (MC-2).No COD design criteria.

SS (TSS)

mg/lmg/l Rangekg/day*

1,000–7,600

30––

644456 – 1,052

4,499

5725 – 212

401

Raw sampled after septage unloading (MC-2).SS loading at 59 percent of design.13 of 14 samples exceeded effluent limit.

Total Kjeldahl Nitrogen (TKN)


150–1,140

50––

130112 – 147

905

71.662.0 – 80.4

498

Raw sampled after septage unloading (MC-2).TN measured as TKN loading at 79 percent of design.14 of 14 samples exceeded effluent limit.

PO4-P


40–304

15–

11.38 – 18

79

0.20.10 – 0.38

1.4

Raw sampled after septage unloading (MC-2).PO4-P loading at 26 percent of design.0 of 14 samples exceeded effluent limit.

NH3-Nmg/lmg/l Range

96–

15–

9683 – 107

673

64.855 – 77

453

Raw sampled after septage unloading (MC-2).0 of 14 samples exceeded effluent limit.

NO3-Nmg/lmg/l Rangekg/d*

30

162

25––

–––

< 1––

E. coli MPN/100 ml – < 1000 Measured at chlorine contact tank

Nematodes Eggs/l – < 1 Measured at chlorine contact tank

* Loading based on plant AADF during the two-week sampling program of 4,474 m3/d.

As of October 2018, the Madaba WWTP was operating at 83 percent of the design hydraulic capacity and 82 percent of the design organic load with influent BOD5 averaging 1,002 milligrams per liter (mg/l), which is normal organic concentration in Jordan. The high-loading


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month is August and, in 2018, the influent flow was 88 percent of the hydraulic design capacity and the organic loading was expected to be similar.

1.2.5 Wastewater Collection Network Based on data extracted from the recent (late 2018 update) geographical information system (GIS) database provided by MWC, the existing wastewater collection network is approximately 146 km long and serviced an estimated 96,100 people in 2015, based on the Jordan census data. The existing sewage collection system connection to the Madaba WWTP is shown in red in Figure 1-5.


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Figure 1-5Madaba City Existing Wastewater Network


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1.2.6 Effluent and Solids ReuseThe Madaba WWTP effluent and biosolids reuse study prepared by Ahmad Abu-Awwad, PhD, for USAID Jordan Water Infrastructure is included in Appendix A of this report. Below is a summary on the current reuse of effluent from the Madaba WWTP.

In 2018, treated effluent from Madaba WWTP was used to supply farms on a daily basis to irrigate their fodder crops (alfalfa, ryegrass, barley, and corn), winter grains (wheat), olives, and cooked vegetables (eggplant and squash), through 33 signed agreements between local farmers and the MWI, of which 25 are active. In 2018, the total cultivated irrigated area was 828 dunum (1 dunum = 1,000 m2).

The effluent is treated and sold to the farmers under the direction of the MWI/WAJ. Based on the agreements between the farmers and the WAJ, the sale price is JD 0.05 per cubic meter per dunum on a daily basis for 365 days per year. The effluent is then supplied to the farms at 3 m3 per day per dunum (JD 0.05 × 3 × 365) on a daily basis, regardless of the crop types and needs.

WAS from the extended aeration process are thickened in a gravity thickener and dried in on-site sludge drying beds. Once the solids are sufficiently dried, they are disposed of on-site by burial. Currently, there is no market for use of sludge as a fertilizer for soil amendment due to the perceived risk by the local population and tight restriction on its use by the Ministry of Agriculture (MoA).

1.2.7 ClimateIn general, Madaba has a hot summer Mediterranean climate. Madaba experiences mild wet winters and dry hot summers. Variations in temperature and rainfall are governed by altitude. Dry hot summers from mid-May to mid-September and rainy, rather changeable, winters from October to May are separated by short autumn and spring seasons. A summary of the Madaba area climate from Jordan Meteorological Department data follows.

Rainfall: The main rainfall season in the Madaba area is from October to May. The average rainfall ranges from 0 millimeters (mm) in summer months to 82.2 mm in January. The annual average from 1978 to 2007 (39 years) was 329 mm.

Temperature: The average minimum temperature ranges from 3.0°C in January to 18.8°C in July. The average maximum temperature ranges from 12.6°C in January to 31.3°C in July.

Relative humidity: The relative humidity is moderate, ranging from 47.9 percent in May to approximately 75.2 percent in January.

Wind: The wind speed is generally consistent throughout the year, ranging from 222 kilometer per day (km/d) in August and October to 289 km/day in March. The annual average is 249 km/d.

Actual sunshine hours: Peak records occurred during the month of July at about 11.0 hours daily compared to potential sunshine hours of about 14.3 hours daily in July. The minimum records occurred during the month of December at approximately 5.4 hours daily compared to potential sunshine hours of about 10.3 hours daily in December.


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Section 2Summary of Wastewater Flows and Loads

2.1 Madaba WWTP Catchment AreaAs outlined in Section 1, only older parts of Madaba City currently have a sewer collection system connected to the Madaba WWTP. The MWI/WAJ has plans to extend the wastewater collection system to new areas around Madaba City under the 2017 Dar Al-Arabia Consultants study, but neither design nor construction has not been funded as of the writing of this report.

The identification and projections for wastewater flows to the Madaba WWTP through the design horizon 2045 are detailed in the Technical Memorandum – USAID Jordan Water Infrastructure, Task 4 Madaba WWTP Expansion – Wastewater Catchment Area and Flow Projections dated December 16, 2018, as included in Appendix B.

2.1.1 Al-Dar Al-Arabia Consultants StudyWastewater networks that are planned but not yet constructed are identified in a study prepared by Al-Dar Al-Arabia Consultants in October 2017, as shown on Figure 2-1. This study presumed that wastewater collected from these new areas would be pumped to the South Amman WWTP, which is not practical because the South Amman WWTP was not designed to receive flows from Madaba City. However, it is practical to connect these planned networks to the existing Madaba WWTP site following plant expansion.

2.1.2 Potential Additional Wastewater Network ExpansionAreas that could be reasonably connected to the Madaba WWTP, but where wastewater collection is not currently planned, do exist. These are populated areas within the Madaba WWTP natural catchment area that are adjacent to planned collection networks and could easily be connected to the network, as shown in Figure 2-2. The potential expansion areas for extension of the wastewater network to include Fayha’a, Ghernatah, Ariesh, Maeen, and Faisaliah in the December 16, 2018 technical memorandum identified above.

Section 2 Summary of Wastewater Flows and Loads

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Figure 2-1Madaba City Planned Wastewater Network Expansion by Al-Dar Al-Arabia Study (2017)


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Figure 2-2Madaba City Wastewater Network Catchment with Existing, Planned, and Potential Networks


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2.1.2.1 Population and Wastewater Flow ProjectionsThe population projections included herein are based on the 2015 Census middle population growth rate for Jordanian, non-Jordanian, and Syrian refugee populations provided by Jordan Department of Statistics (DOS); the middle population growth rate is 1.86 percent in 2020 and decrease over time to 0.88 percent in 2045. The wastewater projections are based on MWI’s 2016 Water Reallocation Policy—100 liter per capita per day (lpcd) water allocation with wastewater generation being 80 percent of the water supply, or 80 lpcd (100 lpcd × 0.80), which is consistent with the wastewater generation percent adopted by the Capital Investment Plan (Section 3, Page 35). Wastewater projections assume that the Madaba City and surrounding areas will receive 100 lpcd of water through the year 2045.

2.1.2.1.1 Existing Wastewater GenerationThe existing wastewater collection system for the Madaba WWTP covers an estimated 90 percent of Madaba City, and about 10 percent of the population of Khaldeyyeh (Abu Ezqal), Khatabiyyeh, and Ma’moneia localities on the west and north side of Madaba City. The existing Madaba WWTP wastewater collection network is shown on Figure 2-1. The Madaba WWTP serviced an estimated population of 90,420 in 2017, and had a monthly average day flow of 6,916 m3/d for 2015–2017. Minimum and maximum monthly average day flow ranged 5,540–7,890 m3/d during that same time frame.

Determining the service population in Madaba City is difficult because of the influx of Syrian refugees. To accurately estimate the service population, CDM Smith utilized MWI’s 2016 Water Reallocation Policy of 80 lpcd of wastewater generation, Jordan’s DOS population estimates, and the Madaba WWTP’s historical flow data for 2015–2017. Analyzing this data yielded that 45 percent of the total population is serviced by the Madaba WWTP.

To verify the presented service population estimates in Table 2-1, BOD5 load contribution was analyzed in conjunction with wastewater contribution per capita. According to the USAID Jordan Wastewater Master Plan, BOD5 load contribution is 65 grams per capita per day for the entire country. This criterion was accepted by the WAJ from studies conducted by other consultants. Utilizing the estimated service populations and historic loading data (2015–2017) from the Madaba WWTP, wastewater flow contribution averaged 66 lpcd. This aligns with USAID’s Jordan Wastewater Mater Plan and confirms CDM Smith’s service population estimates. Table 2-1 presents the Madaba WWTP AADF, total population, wastewater service population, percentage of total population serviced, AAD BOD5 loading and BOD5 contribution per capita for 2015–2017.

Table 2-1 Madaba WWTP AADF, Total Population, Service Population, AAD BOD5 Loading, and BOD5 Contribution

Date (Year)

AADF1

(m3/d)Total

Population2Service

Population3

Percentage of Pop.

Serviced (%)

AAD BOD5 Loading4

(kg/d)

Wastewater Contribution

(lpcd)2015 6,604 189,700 82,552 44 5,996 732016 7,110 194,500 88,870 46 5,217 592017 7,234 199,500 90,420 45 6,041 67

3-Year Average

6,981 – – 45 5,751 66

1Annual Average Day Flow (AADF), 2Total population estimates are based on Jordan Department of Statistics data for the governate of Madaba, 3Service populations are based on MWI’s 2016 Water Reallocation Policy (80 lpcd of wastewater


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generation) (there is some uncertainty in the population serviced due to the influx of Syrian refugees), 4Annual average daily (AAD) BOD5 loading based on lab results provided by MWC

2.1.2.1.2 Projected Wastewater GenerationThe principal source of domestic wastewater is from residential areas. For well-defined residential areas, where the population can be estimated with some reliability and water consumption is based on measured supply data, wastewater generation can be estimated on the basis of the presumed population multiplied by the per capita water consumption and an estimated return rate. For Madaba City, a wastewater generation rate of 80 percent of the per capita water consumption is used to determine the volumes of wastewater returned to the sewer network.

Figure 2-2 identifies three areas (existing, planned, and potential) wastewater collection networks that would contribute to the expansion of the Madaba WWTP. These three wastewater collection areas are:

Existing Wastewater Network – projected wastewater flows from Madaba City’s existing sewer network

Planned Wastewater Network Expansion – projected wastewater flows from planned areas covered by the Al-Dar Al-Arabia study. These locations are Madaba City, Ma’moneia, Jubail, Khatabiyyeh, and Khaldeyyeh (Abu Ezqal).

Potential Wastewater Network Expansion – projected wastewater flows from potential (new) areas that could be connected to the Madaba WWTP sewer network but not currently planned to be connected. These locations include parts of Jrainah, Ghernatah, Wasiyyeh, Maeen, Faisaliah, and Libbeh.

The population projections at 5-year intervals through the project design horizon of 2045, which would be served with piped networks and contribute to the Madaba WWTP expansion, are presented in Table 2-2.

Table 2-2 Population Served by Wastewater Network and Madaba WWTP Expansion1

Projected Population Served by the Madaba WWTP ExpansionMadaba WWTPWastewater Collection

Networks 2015 2020 2025 2030 2035 2040 2045

Existing network 105,353 115,632 125,747 135,189 142,044 148,896 155,580

Existing and planned networks 130,567 143,306 155,842 167,544 176,039 184,532 192,816

Existing, planned, and potential networks 134,762 147,909 160,849 172,926 181,694 190,460 199,010

1Source: December 16, 2018 technical memorandum by USAID Jordan Water Infrastructure

Table 2-3 lists wastewater flow projections at 5-year intervals through the project design horizon of 2045 for the Madaba WWTP expansion. The wastewater generation rate of 80 lpcd was used in accordance with MWI water allocation policy.


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Table 2-3 Wastewater Contribution by Network Status1

Wastewater Generation Projections at Rate of 80 lpcd(m3/d)

Percent of

Existing

Madaba WWTPWastewater

Collection Networks 2015 2020 2025 2030 2035 2040 2045 %

Existing network 8,428 9,251 10,060 10,815 11,363 11,912 12,446 100Existing and planned networks 10,445 11,462 12,467 13,404 14,083 14,763 15,425 124

Existing, planned, and potential networks

10,781 11,833 12,868 13,834 14,536 15,237 15,921 128

Projected influent flow for this study 8,428 9,000 10,000 12,000 13,500 15,000 16,0002 –

1Source: December 16, 2018 technical memorandum by USAID Jordan Water Infrastructure. 2An additional 400 m3/d of trucked septage is presumed for 2045.

The projected wastewater influent to Madaba WWTP in the project design horizon year 2045 from a population of 199,010 people is 15,921 m3/d AADF, assuming population growth and water use trends continue as estimated by the Jordan DOS. This wastewater flow projection is rounded up to 16,000 m3/d AADF.

The recommended 2045 design horizon capacity for the expansion of Madaba WWTP is to be rounded up from the calculated influent flow (AAD loading of 13,010 kg/d as BOD5 and AADF of 16,000 m3/d), which is explained in the wastewater load projection system in Section 2.3.2 of this report. Figure 2-2 is a graph of the data presented in Table 2-3. There is an additional presumed contribution from trucked septage that would decrease (as new sewer networks are constructed) to a volume of 400 m3/d in the year 2045, which is not shown in Figure 2-3.

Figure 2-3Madaba Wastewater Influent Flow Projections Graph


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2.1.3 Plant Influent Flow LagThe wastewater influent flow projections for Madaba WWTP include populations from areas that are currently without a sewer collection network. Because the new sewer network will have to be constructed before the flow can reach the WWTP, there will be a lag on the flow increase corresponding to the construction of new networks. However, the projected population that will be served by the future new sewer network is relatively small compared to the projected population connected to the existing sewer network; therefore, phased construction of the WWTP expansion is not suggested.

Table 2-4 compares the wastewater flows from the new network area to the flows from the existing sewer network. The percentages in Table 2-2 are the flow projections from Table 2-1 divided by the expanded WWTP capacity of 16,000 m3/d AADF, which was then multiplied by 100 to determine the percentage.

Table 2-4 Wastewater Contribution by Network Status1

Flows as Percentage of Plant Expansion Capacity (16,000 m3/d)Madaba WWTPWastewater

Collection Networks 2015 2020 2025 2030 2035 2040 2045

Existing network NA 58% 63% 68% 71% 74% 78%Existing and planned networks NA 72% 78% 84% 88% 92% 96%

Existing, planned, and potential networks NA 74% 80% 86% 91% 95% 100%

1Source: December 16, 2018 technical memorandum by USAID Jordan Water Infrastructure.

The newly expanded Madaba WWTP should be operating at 63 percent capacity on flow from the existing Madaba City collection network in the year 2025. Flow from the existing network will account for 78 percent of the WWTP capacity in 2045. The wastewater from the planned and potential networks will account for 16 percent of the WWTP capacity in 2025, and 22 percent in 2045.

Because the existing networks contribute 78 percent of the total project wastewater flow to the expanded Madaba WWTP, there may not be a financial advantage to phasing the construction of this plant expansion.

2.1.4 Wastewater Flow Variations2.1.4.1 Seasonal VariationsThe ADMMF typically occurs during the summer months of July and August, consistent with the general pattern in Jordan when overseas Jordanians return home for the summer holidays. August average monthly flow is typically 6 to 9 percent higher than the average annual flow.

The MDF and PHF typically occur during the winter wet season of November through April as a result of stormwater (surface water) infiltration into the wastewater collection system and mixing with the sewerage. A storm event in February 2018 had a measured maximum hourly flow at 18,240 m3/d, which approached the existing headworks design peak hourly capacity of 19,000 m3/d. However, this is not an accurate representation of stormwater (combined with sewage) flows to the WWTP because sometimes the operators divert high storm flow to the Wadi Al-Habeth from Diversion Chamber No. 1, which is upstream of the WWTP influent flowmeter.


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2.1.4.2 Diurnal Influent FlowsHourly flow readings measured by the plant influent flowmeter from late October 2018 are presented in Figure 2-4. This diurnal flow pattern was used to devise the 24-hour flow-weighted composite sample collected by the automatic composite sampler during the two-week sampling in October and November 2018.

The diurnal low- and high-flow times are not consistent with diurnal patterns seen in North America, but do appear to be consistent with water use practices in Jordan.

Figure 2-4Madaba Wastewater Diurnal Influent Flow

2.1.5 Summary of Wastewater Flow ProjectionsThe 2045 design horizon wastewater flow projections for the expansion of Madaba WWTP is AADF of 16,000 m3/d and a PHF factor of 2.5 AADF. Influent combined sewer and stormwater flow in excess of the design PHF of 40,000 m3/d will be diverted to the WWTP’s influent stormwater management (combined sewer) ponds until the storm passes and influent flow returns to normal; the water in the ponds will then be pumped back to the WWTP for treatment. If the influent stormwater (combined sewer) ponds are full, it will be necessary to bypass the influent flow around the WWTP to the wadi to keep from damaging the WWTP infrastructure. However, this would only be in an emergency resulting from a high precipitation storm event.


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The existing equalization ponds that will be repurposed as influent stormwater management ponds are from the 1980 WWTP construction and will need to be enlarged and rehabilitated; this will be investigated in the future during the preliminary design phase.

2.2 Wastewater Load ProjectionsThe strength or concentration of the biological load currently received at Madaba WWTP is very high with post-septage influent BOD5 averaging 768 mg/l, COD averaging 1,660 mg/l, and TSS averaging 644 mg/l, based on the October–November 2018 sampling program shown in Table 1-3. However, this data set only represents a short period for the annual loads received at the WWTP. Historic wastewater influent concentration data provided by MWC for 2015–2017 was combined with and analyzed against the data collected October–November 2018. The projection for future wastewater concentration and loading received at the expanded Madaba WWTP is presented in Table 2-5. According to MWC and review of available GIS data, industrial wastewater is not discharged to the existing Madaba WWTP sewer collection network. This municipal strength is consistent with other WWTPs around Jordan, as a result of water scarcity.

2.3 Summary of Projected Wastewater Flows and Loads2.3.1 MethodologyThe MWC provided three years of operating data form the Madaba WWTP from January 1, 2015 through December 31, 2017. A special two-week long sampling event in October and November 2018 was evaluated to determine the updated influent flows and loads for the current operating conditions. Analysis of historical daily plant influent data for the study period was performed for flow, COD, BOD5, TSS, TKN, ammonia, and TP.

Average day design concentration for BOD5 was calculated using USAID’s Jordan Wastewater Master Plan suggested BOD5 load contribution of 65 grams per capita per day and the Jordan Water Allocation Policy where cities in Jordan other than Amman are allocated with a water supply of 100 lpcd with 80 percent of that supply returning as wastewater. This criterion yields a design influent BOD5 concentration of 813 mg/l.

Influent organic loads are presented in this report as BOD5, which represent the BOD5

measurements without the addition of nitrification inhibitor. When nitrification inhibitor is added, it will also impact the heterotrophic bacteria and the BOD5 will be underestimated. The special sampling conducted in October–November 2018 showed that inhibited/uninhibited BOD5 averaged 0.90 in the plant influent samples.

A key step in influent data analysis is to develop mass loadings and mass loading peaking factors to account for changes in concentration during peak flow events. The mass loading peaking factors are applied along with flow peaking factors to develop design concentrations for each constituent at each flow condition.

The procedure outlined below accounts for the dilution in concentration or increase in loading of some parameters during peak flow conditions that may occur during wet weather.

1. Determine AAD mass loads.


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The daily mass loads for the influent parameters listed were calculated using the following equation:

KCQT

where:

T = mass load (kg/d)

Q = flow (m3/d)

C = concentration (mg/l)

K = conversion constant, 0.001

2. Determine ADMM loading peaking factors.

The ADMM load was divided by the AAD load to determine the ADMM peaking factor for COD, BOD5, TSS, TKN, ammonia, and TP.

It should be noted that, because ratios were based on the two-week sampling event, the peaking factors calculated for TKN, ammonia, and TP were equal to the peaking factors for COD.

3. Determine MD loading peaking factors.

The 99th percentile of daily mass load was divided by the average of the daily mass load to determine the MD peaking factor for COD, BOD5, TSS, TKN, ammonia, and TP.

Because ratios were based on the two-week sampling event, the peaking factors calculated for TKN, ammonia, and TP were equal.

4. Calculate design ADMM and MD concentrations.

Because the peaking factors obtained for the historical data for BOD5 and TSS did not align with what was calculated for COD, the peaking factors obtained for COD were used for all parameters based on the two-week influent sampling data.

Subsequently, using the design average daily mass loads along with the mass loading peaking factors developed previously, the ADMM and MD concentrations were developed by dividing the mass loading at each flow condition by the historical flow at that condition. This provides a concentration that may be used with projected flows at each condition to project future loadings. ADMM and MD influent concentrations were calculated at ADMMF and MDF, respectively, using the following formula:

𝐶 = 𝑇/(𝑄 𝑥 𝐾)

5. Calculate ADMMF and MDF peaking factors.

ADMMF peaking factors were taken from the maximum average month of the daily flows. The MDF peaking factor used the 99th percentile of day flow of the data set and divided by the average daily flow of the data set.


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2.3.2 Influent Flows and LoadsTable 2-5 summarizes the influent data, peaking factors, and concentrations developed according to the aforementioned procedure for the Madaba WWTP. The concentrations used to calculate loads in Table 2-5 were obtained by applying ratios calculated from the two-week sampling event applied to long-term averages from the plant data and scaling based on a design average BOD concentration of 813 mg/l. Some values were adjusted slightly if the ratio resulted in a value outside of the normal range for municipal wastewater (see process technical memorandum for details). The ADMM and MD load peaking factors were calculated based on historical data and checked based on typical factors for municipal wastewater. The same peaking factor was used for all loading criteria.

Table 2-5 Influent Peaking Factors, Flows, and Loads

Peaking FactorsParameter

AAD ADMM MDFlow 1.0 1.2 1.8COD mass load 1.0 1.3 1.6BOD5 mass load 1.0 1.3 1.6TSS mass load 1.0 1.3 1.6TKN mass load 1.0 1.3 1.6NH3 mass load 1.0 1.3 1.6TP mass load 1.0 1.3 1.6

Influent Flows and Loads at Current Operating ConditionsParameter Unit

AAD ADMM MDFlow m3/d 7,800 9,360 14,040

mg/l 1,590 - -COD

kg/d 12,402 16,127 19,839mg/l 799 - -

BOD5 kg/d 6,236 8,109 9,975mg/l 537 - -

TSSkg/d 4,189 5,449 6,701mg/l 130 - -

TKNkg/d 1,014 1,320 1,629mg /l 118 - -

NH3-Nkg/d 917 1,193 1,473mg/l 16 - -

TPkg/d 125 159 197

Raw Influent Flows and Loads at 16,000 m3/d AADF Treatment CapacityParameter Unit

AAD ADMM MDFlow m3/d 16,000 19,200 28,800

mg/l 1,590 - -COD

kg/d 25,440 33,072 40,704mg/l 813 - -

BOD5 kg/d 13,012 16,916 20,819mg/l 593 - -

TSSkg/d 9,487 12,334 15,180mg/l 450 - -

VSSkg/d 7,199 9,359 11,519

TKN mg/l 130 - -


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kg/d 2,080 2,704 3,328mg/l 103 - -

NH3-Nkg/day 1,648 2,142 2,637mg/l 17 - -

TPkg/day 272 354 435

Table 2-6 shows the primary clarifier TSS and BOD removal efficiencies used for design. Empirical primary clarifier efficiencies were used because Madaba does not currently have primary clarifiers for comparison. Data from other treatment plants in Jordan was reviewed to confirm these empirical removal efficiencies are appropriate for similar wastewaters. The COD, TKN, and TP removal efficiencies were calculated using the BioWin model, depending on the influent fractions used in the model based on the two-week sampling results. The BioWin model also takes into account return streams from the solids handling system which will be returned upstream of the primary clarifiers. Return streams will increase influent TSS loading by 2-5 percent. Additional bench-scale testing may be conducted during development of the BODR to further evaluate the anticipated primary clarifier removal efficiencies.

Table 2-6 Primary Clarifier Removal Efficiencies Used

Percent Removal EfficiencyParameter

AAD (%) ADMM (%) MD (%)TSS Removed 49 50 49BOD5 Removed 38 38 37

2.3.2.1 Septage LoadsThe septage that is trucked to Madaba WWTP comes from household wastewater holding tanks with no outlet to drain the supernatant; they are not septage tanks with drain (leach) fields that are used for onsite wastewater treatment in rural parts of North America.

The septage truck is hired by the household to pump out the septage holding tank when full, and, generally, only one truck load (up to 15 m3) is removed until the holding tank is full again. These holding tanks are typically very large (30–60 m3), so unless the truck driver forces the suction pipe to the bottom of the holding tank, only the low-strength supernatant is removed. Therefore, the concentration of the septage delivered to the WWTP is highly variable.

Table 2-7 shows the septage flow and loading used for design based on 20 to 30 truckloads per day with an average daily volume of 400 m3/d; in 2045, and presumed contribution from trucked septage that would decrease (as new sewer networks are constructed) from the currently levels of more than 600 m3/d for 6 days per week. For alternatives that include anaerobic digestion, the septage will be added to the primary sludge gravity thickeners and almost all the septage load will be transferred directly to the digesters with the primary sludge. The septage flow is presumed to be the same for all design conditions because it is unlikely that the peak septage flow will happen at the same time as peak influent flow. Septage load peaking factors are applied to provide some allowance for increased loading during higher influent flow conditions. The septage loads in Table 2-7 were derived from the results of the two-week-long sampling program conducted by RSS under subcontract to CDM Smith between October 28 and November 13, 2018.


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Table 2-7 Madaba WWTP Septage Flows and Loads for 2045

Flow PF Flow

Load PF COD BOD5 TSS VSS TKN NH3 TP

Units – m3/d – mg/l mg/l mg/l mg/l mg/l mg/l mg/lAAD 1.0 400 1.0 5,000 2,482 2,434 1,834 185 93 25ADMM 1.0 400 1.3 6,500 3,226 3,164 2,384 241 121 33MD 1.0 400 2.4 12,000 5,956 5,840 4,400 444 223 60

Units – – – kg/d kg/d kg/d kg/d kg/d kg/d kg/dAD – – – 2,000 993 973 733 74 37 10ADMM – – – 2,600 1,291 1,265 953 96 48 13MD – – – 4,800 2,383 2,336 1,760 178 89 24

2.3.2.2 WWTP Operation RangeThe WWTP’s biological processes are designed for an average day BOD load of 13,010 kg/d for a population of 199,010 people based on published data for BOD5 produced per person per day (65 grams per day per person for Jordan) as discussed in the Madaba WWTP expansion Process Design Approach technical memorandum included in Appendix B.11 The WWTP will treat any combinations of flow and BOD5 concentration up to the average of 13,010 kg/d (flow × concentration = load).

The flow rate is important for plant hydraulic design, but is not so important to the biological treatment process design. The design influent flow was derived from the Jordan water allocation policy with wastewater generation of 80 liters per capita per day (lpcd), while the Madaba City area is actually producing approximately 66 lpcd of wastewater. It is this difference between the water allocation policy and the current situation that drives the differences in the BOD5 influent concentrations, but this does not matter because the WWTP is designed for the biological loading based on the population discharging to the WWTP. For example:

If the Jordan water allocation policy is achieved, and each person produces 80 liters per day of wastewater, then a service population of 199,010 people will produce on average 15,920 m3/d (rounded up to 16,000 m3/d) of wastewater with an average BOD5 concentration of 813 mg/l.

If the water supply to the Madaba WWTP collection area remains at current levels, then the service population of 199,010 people will produce on average 13,135 m3/d of wastewater with an average BOD5 concentration of 990 mg/l.

In either situation, the WWTP will have the same biological loading because the design is based on the population served and the BOD5 contribution of 65 grams per person per day. The Madaba WWTP is suitably designed based on the biological loading for the projected population to be served by the WWTP.

To illustrate the WWTP’s loading capacity to handle varying influent wastewater flows and concentration, Figure 2-5 is a graphic reparation of the new WWTP capacity in terms of influent BOD5 concentration and the influent flow rate. Influent flow greater than 16,000 m3/d (to the right of the design point and below the blue line) is allowed for short-term high-influent rates caused by a storm event. The WWTP has the capacity to received storm flow up


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to 40,000 m3/d (peak flow) and, at such a flow, the wastewater concentration is less owing to delusion by the rainwater.

Figure 2-5Madaba WWTP Operation Range

2.3.3 Peak Hourly FlowThe proposed design PHF is 40,000 m3/d. This represents a peaking factor of 2.5 AADF. The expanded facility may receive higher PHFs and the existing facility has flow equalization ponds which will be maintained after the expansion as influent stormwater management ponds for the combined stormwater and sewage flow. PHFs up to 40,000 m3/d will be directed to the expanded plant, which will be designed to provide this hydraulic capacity. Flows over 40,000 m3/d will be diverted to the influent stormwater management ponds to be treated later. When the influent stormwater ponds are full and the plant is treating 40,000 m3/day, excess flow will be diverted to the wadi. The stormwater management ponds provide primary treatment through settling of the raw wastewater prior to discharge. Similar design approach and PHF peaking factor was previously used for the East Jerash WWTP.

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Section 3Treatment Requirements and Effluent Standards

3.1 IntroductionThis section defines the future treatment objectives in Madaba by listing the effluent wastewater and biosolids standards to be met. It also outlines the standards used for the design of existing facilities. In the end, the wastewater effluent design criteria are defined along with the sludge characteristics to be met, all with the intent of maximizing reuse.

3.2 Jordanian Effluent and Sludge Disposal Standards3.2.1 Standards for Wastewater Discharges and Effluent ReuseThe third edition of the Jordanian Standard JS893/2006, issued on November 13, 2006, contains standards for reclaimed domestic wastewater. It lists a wide range of parameters that must be achieved for various reuse options.

The standard divides the reuse into three categories:

Category 1. Discharge of reclaimed effluent to wadi, streams, and water bodies

Category 2. Artificial recharge of groundwater aquifer

Category 3. Reuse for irrigation of crops

The JS require different levels of treatment, depending on the end use of the treated effluent. Category 3, dedicated for the irrigation of flowers, as presented in Table 3-1, requires the highest level of treatment. These standards forbid the use of reclaimed effluent for the irrigation of crops that can be eaten raw.

Table 3-1 includes the parameters that could be controlled by biological treatment (e.g., BOD5, COD, TN) and Table 3-2 contains the majority of parameters not affected by biological treatment (e.g., heavy metals, total dissolved solids [TDS], phenol). The proposed wastewater treatment plant processes will not be selected to remove any of these pollutants, although some limited removal may occur. The conventional wastewater treatment processes typically do not remove or treat these pollutants. Use of some chemicals, such as ferric chloride for the H2S removal at the biosolids treatment processes, can increase effluent TDS and Fe concentrations. In addition, gas chlorine use for the effluent disinfection may have a small impact on the effluent TDS concentration.

The design intent for treatment upgrades and improvements in Madaba is to meet Category 3(A) quality standards dedicated for irrigation of cooked vegetables, parks, and playgrounds.

Not all the COD present in the wastewater influent is biodegradable with conventional municipal wastewater treatment process, and a fraction of the influent COD will carry through in the effluent. This fraction is typically about 5-10 percent of the influent concentration. As

Section 3 Treatment Requirements and Effluent Standards

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indicated in prior sections, the influent COD is high and, during the October–November 2018 sampling program, the high measured concentration was 2,097 mg/l (see Table 1-3). In such conditions the effluent COD could be 172 mg/l and exceed the COD limit for effluent Category 3(A).

Table 3-1 Characteristics of Effluent for Reuse (Categories 1 to 3)1

Irrigation (Category 3)

Parameter Unit

Discharge to Wadi

(Category 1)

Artificial Recharge of

Ground-water

Aquifer(Category 2)

Group A:Cooked

Vegetables, Parks, and

Playgrounds

Group B: Fruit

Trees, Green Areas

Group C: Field

Crops, Industrial Products, Forestry

Cut Flowers

BOD5 60 15 30 200 300 15COD 150 50 100 500 500 50DO > 1 > 2 > 2 – – > 2TSS 60 50 50 200 300 15

NO3 as NO3 mg/l 80 30 30 45 70 45NH4

+ – 5 – – – –Total-N 70 45 45 70 100 70

PO4 as PO4 15 15 30 30 30 30FOG 8 8 8 8 8 2

E. coliMPN/100 ml

1000 < 2.2 100 1000 – < 1.1

pH – 6 to 9 6 to 9 6 to 9 6 to 9 6 to 9 6 to 9Turbidity NTU – 2 10 – – 5

Nematodes Eggs/l ≤ 0.1 ≤ 1 ≤ 1 ≤ 1 ≤ 1 ≤ 1Note: 1. Source: Jordanian Standard JS893/2006 issued on November 13, 2006

Table 3-2 Allowable Limits for Effluent for Wadi Disposal, Aquifer Recharge, and Irrigation

Allowable Limit

Parameter Abbreviation UnitWadi

DischargeAquifer

Recharge Irrigation (Category 3)

(Category 1) (Category 2)A+B+C

Categories Cut FlowersPhenol Phenol mg/l < 0.002 < 0.002 < 0.002 < 0.002

Detergent MBAS mg/l 25 25 100 15Total Dissolved

Solids TDS mg/l 1500 1500 1500 1500

Chloride Cl mg/l 350 350 400 400Sulfate SO4 mg/l 300 300 500 500

Bicarbonate HCO3 mg/l 400 400 400 400Sodium Na mg/l 200 200 230 230

Magnesium Mg mg/l 60 60 100 100Calcium Ca mg/l 200 200 230 230Sodium

Adsorption Ration

SAR – 6 6 9 9

Aluminum Al mg/l 2 2 5 5Arsenic As mg/l 0.05 0.05 0.1 0.1


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Allowable Limit

Parameter Abbreviation UnitWadi

DischargeAquifer

Recharge Irrigation (Category 3)

(Category 1) (Category 2)A+B+C

Categories Cut FlowersBeryllium Be mg/l 0.1 0.1 0.1 0.1Copper Cu mg/l 0.2 1.5 0.2 0.2Fluoride F mg/l 1.5 2 2 2

Iron Fe mg/l 5 5 5 5

Lithium Li mg/l 2.5 2.5

2.5(0.075 for

citrus crops)

0.075

Manganese Mn mg/l 0.2 0.2 0.2 0.2Molybdenum Mo mg/l 0.01 0.01 0.01 0.01

Nickel Ni mg/l 0.2 0.2 0.2 0.2Lead Pb mg/l 0.2 0.2 0.2 0.2

Selenium Se mg/l 0.05 0.05 0.05 0.05Cadmium Cd mg/l 0.01 0.01 0.01 0.01

Zinc Zn mg/l 5 5 5 5Chrome Cr mg/l 0.02 0.05 0.1 0.1Mercury Hg mg/l 0.002 0.001 0.002 0.002

Vanadium V mg/l 0.1 0.1 0.1 0.1Cobalt Co mg/l 0.05 0.05 0.05 0.05Boron B mg/l 1 1 1 1

Cyanide CN mg/l 0.1 0.1 0.1 0.1

3.2.1.1 Location of Effluent Monitoring for Regulatory ComplianceTypically, effluent water quality for regulatory compliance is monitored at the point where the effluent leaves the plant boundary or at the point where the plant no longer has control of the effluent. However, to maximize the opportunity for reuse of effluent for irrigation, a large portion will be stored in large ponds until needed by the local farmers. Plant operations have little control over the water quality in these large ponds because the ponds are open to the air and the sunlight and exposure to the air, such as algae growth and birds resting in the water and leaving their droppings.

To mitigate the uncontrollable effluent of the large effluent storage ponds, plant effluent water plant performance monitoring will be collected from the outlet of the secondary clarifiers. Except for E. coli, the effluent would be monitored at the discharge of the chlorine contact tank (CCT).

3.2.2 Total Nitrogen Treatment Requirements and ConcernsAs shown in Table 3-1, the nitrate discharge limit for cooked vegetables (Category 3[A]) is 30 mg/l as NO3, which is equivalent to 6.8 mg/l for nitrate as nitrogen (NO3-N). This limit is not practical when selecting the required treatment process and attempting to optimize the reuse intent of this project. The following are the challenges with this limit and conditions that make this limit questionable:


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A nitrate-nitrogen limit of 6.8 mg/l is the approximate treatment limit for typicalbiological nutrient removal technologies for such highly concentrated influent. Anythinglower would require consideration of other nutrient removal technologies, such as deepbed denitrification filters with carbon source addition. This level of treatment iscommon in many countries for direct discharge to water bodies, but not where effluentreuse is practiced.

The Jordanian Reuse Standards (JS893/2006) for effluent total nitrogen (TN ≤45 mg/l)and nitrate-nitrogen (6.8 mg/l) are not consistent with each other. For a WWTP thatachieves complete nitrification, the total nitrogen in the effluent is comprised of nitrate-nitrogen, nitrite-nitrogen (negligible amount), and nonbiodegradable organic nitrogen.Because the limit for TN is 45 mg/l and NO3-N is 6.8 mg/l, the remaining 38.2 mg/lwould be recalcitrant dissolved organic nitrogen (rDON). Fourteen days of effluentsamples collected at the Madaba WWTP in October–November 2018 had an averagedissolved organic concentration of 1.8 mg/l. The required adjustment to the dischargelimits would be an increase in the NO3-N limit or a decrease in the TN limit.

The 1995 version of the Jordanian Effluent Quality Standard defined a nitrate-nitrogenlimit of 25 mg/l and a total nitrogen limit of 50 mg/l for discharge to wadis andcatchment areas. These limits are more in balance with expected discharges from aWWTP.

The Jordanian Drinking Water Standard (JS286/2015) for NO3 is 50 mg/l, while thewastewater discharge limit for irrigation of cooked vegetables is 30 mg/l. Since thepotable water limit is higher, the wastewater treatment facility may have to reducenitrogen in the effluent before it is discharged to the wadi. If 50 mg/l of nitrate isconsidered acceptable for human consumption, then it would be appropriate for thereuse standard to be at the same or higher limit.

A low effluent limit for nitrate results in added construction and operation cost for newor upgraded wastewater treatment facilities. Greater denitrification volume is requiredto oxidize nitrate and to provide an effluent with less than 30 mg/l of NO3. This unusualrequirement is an apparent error in terms, so an effluent nitrate as nitrogen (NO3-N)concentration of 10 mg/l is used for process sizing.

Other wastewater treatment plants in Jordan were recently constructed to meet higherNO3 limits and were also designed for water reuse of the effluent. For example, the WestJerash Wastewater Treatment Plant was designed to meet an NO3 limit of 132 mg/l asthe ion, rather than 30 mg/l, as defined in the JS. The WWTP designers presumed thatthe JS of 30 mg/l is for nitrate as nitrogen (NO3-N) and not nitrate (NO3). This is asignificant difference and appears to be more applicable with the intent for waterpollution control and reuse in Jordan. Other recently constructed or under-constructionWWTPs were also designed for higher limits on nitrate (Shobak WWTP – 30 mg/l NO3-N, North Shouneh WWTP – 15.5 mg/l NO3-N).

Designing a WWTP for such a low nitrate limit contradicts the intent of providingquality effluent that farmers can use for irrigating certain crops. High concentrations ofnitrate are detrimental to the health of water bodies, but are invaluable to farmersbecause it provides the nutrients needed to promote plant growth. If nitrate isunnecessarily removed at the treatment plant, then farmers may be required to add


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fertilizer to supplement their needs. This presents a financial burden to the farmers while contradicting the intent of reusing wastewater effluent.

In summary, an effluent nitrate-nitrogen concentration of 10 mg/l is proposed for the new Madaba WWTP design. All the BNR treatment alternatives sizing was developed to achieve effluent nitrate-nitrogen concentration of 10 mg/l.

3.2.3 Total Dissolved Solids and Requirements and ConcernsTable 3-2 lists the JS893/2006 for Total Dissolved Solids for treated wastewater reuse in agricultural irrigation as 1,500 mg/l. The TDS concentrations in the Madaba WWTP influent range from 137 to 2,292 mg/l, with an average of 1,193 mg/l. Implementing chlorine gas for disinfection is not a concern regarding raising the effluent TDS concentration because chlorine gas only raises TDS concentration by 1.0 mg/l per milligram of chlorine according to “Technical Note: Common Water Treatment Chemicals and Calcium Carbonate Saturation” by Trussel et al. published in the American Water Works Journal in November 2017. Chlorine gas disinfection should not require more than a maximum dosage of 20 mg/l, of which 10 to 18 mg/l would be consumed to maintain a residual concentration of 2 mg/l. However, there are other sources of TDS within the treatment process that may add to the effluent TDS concentration. For example, ferric chloride addition to solids treatment for H2S control.

3.2.4 Industrial Effluent StandardIndustrial effluents are controlled by JS 202/2007, which specifies the quality of industrial effluent to be used for irrigation or disposal to streams and rivers. In addition, the WAJ issued regulations for the characteristics of industrial effluent to be discharged to the public sewer system. WAJ regulations require maximum pollutant concentrations of 800, 1,100, 50, 50, and 2,100 for BOD5, TSS, TP, FOG, and COD, respectively.

3.2.5 Jordanian Standards for Treated Sludge and Sludge Disposal (JS1145/2016)

The Jordanian Standard for treated sludge (JS1145/2016) specifies the conditions that the sludge produced from domestic wastewater treatment plants should meet to be used as soil amendment (improve soil characteristics) for pastureland or to be disposed in landfill.

The standard divides the sludge into three classes according to the end use and level of treatment:

First-class is allowed to be used to improve the properties of the soil (soil conditioning) or to be disposed of in the landfill.

Second-class is allowed to be used to improve the properties of the soil (soil conditioning) or to be disposed of in the landfill.

Third-class is only allowed to be disposed of in the landfill.

Reuse of first- and second-class sludge from wastewater treatment plants is only permitted for improvement of the soil properties of the pasture lands, or for disposal in landfills.

The standard specifies the maximum concentration of trace metals and pathogens and the annual application rates and maximum accumulation limits.


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Producing first-class sludge requires advanced treatment methods to comply with the required microbiological quality and disinfection and has the same disposable requirements as second-class biosolids.

Table 3-3 presents the maximum allowable concentrations. Table 3-4 presents the annual pastureland application rates and maximum accumulation limits.

Table 3-3 Maximum Concentrations Allowed in Biosolids

Parameters and Other Symbol Unit Concentration

Conditions First-Class Second-Class Third-Class

Arsenic As 41 75 75

Cadmium Cd 40 40 85

Chromium Cr 900 900 3,000

Copper Cu 1,500 3,000 4,300

Mercury Hg mg/kg 17 57 57

Molybdenum Mo Dry Weight 75 75 75

Nickel Ni 300 400 420

Selenium Se 100 100 100

Lead Pb 100 840 840

Zinc Zn 2,800 4,000 7,500

Moisture level percent 10 40 –

Total Fecal coliform

TFCC MPN/gm 1,000 200,000 –

Salmonella 3 – –

Nematode egg/4 gm dry < 1 – –

Virus unit/gm dry < 1 – –

Table 3-4 Annual Application Rates and Maximum Accumulation Limits in Soil

Parameters SymbolAnnual application rate

(kg/ha/year)

Maximum accumulation limits in soil

(kg/ha)Arsenic As 1 20

Cadmium Cd 1 20Chromium Cr 25 500

Copper Cu 35 700Mercury Hg 0.85 17

Molybdenum Mo 0.9 18Nickel Ni 5 100

Selenium Se 2 40Lead Pb 11 220Zinc Zn 50 1,000

3.2.5.1 Sludge Treatment and Disposal for Madaba WWTPThe JS 1145/2016 is very restrictive about reusing biosolids from WWTP and limits use to soil conditioning on pasture lands or landfill for first- and second-class biosolids and landfill only for third-class. Because pasture lands within a reasonable distance for the Madaba WWTP


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were not identified by the Reuse Study, all sludge from the Madaba WWTP will likely be disposed via landfill; which do not require content test reports on the sludge from WWTPs.

Because there are no practical reuse options for the sludge, and it will all be landfilled, there is no advantage to stabilizing the sludge to achieve second-class biosolids. Therefore, the sludge treatment objectives (third-class biosolids) are volume reduction and dewatering to reduce the cost of transporting the sludge to landfill. There is no limit on water content for the landfill sludge disposal, but sludge will be dewatered to a minimum dry solids content of 20 percent (not more than 80 percent moisture content).

3.3 Current Disposal Practices and Considerations3.3.1 Current Sludge Disposal PracticesThe utilization of dry sludge from WWTPs for soil stabilization or as fertilizer on agricultural lands (except grazing lands) is currently prohibited by Jordan regulations. At the As-Samra WWTP, the largest in Jordan, where heated mesophilic anaerobic digestion was installed for sludge stabilization and approximately 3,000 m3/d of digested sludge is produced at 3-percent solids. Sludge stabilization in anaerobic digesters and drying on the old waste stabilization lagoon beds is the current process employed. The cake sludge complies with the second-class and is stockpiled at the old plant site without utilization. There are discussions regarding utilization of the cake at a cement factory for fuel, but this potential beneficial reuse, or any other reuse, has not proceeded any further.

Liquid sludge from central WWTPs in Jordan is transported by tankers to Ain Ghazal Pretreatment plant where it is conveyed through 40 km pipeline to the As-Samra WWTP for treatment. Northern WWTPs transport liquid sludge to the Al-Ekeder landfill. Dry sludge is also transported to Al-Ekeder landfill, Lajoon landfill, and Greater Amman Municipality landfills from northern, central, and southern WWTPs, respectively. The Al-Ghabawi landfill located about 25 km east of Amman is currently refusing to accept sludge from WWTPs, leaving Al-Ekeder landfill as the only facility approved to received sludge that would accept sludge Madaba WWTP.

Even though there remains a desire to reuse sludge, beneficial reuse remains limited in Jordan because of regulations.

3.3.1.1 Madaba WWTPSludge from the secondary clarifiers following the aeration process is thickened to between 2- and 3-percent solids and then pumped to drying beds for further dewatering to over 15-percent solids. The dried sludge is then disposed in unlined and monitored earth trenches on the WWTP site. In wintertime, when the sludge drying bed capacity is not sufficient, a mechanical screw press is available, but its use is minimized due to the cost of polymer.

3.3.1.2 Ramtha WWTPSludge from the secondary clarifiers (following the aeration process) is thickened to between 2- and 3-percent solids and then pumped to drying beds for further dewatering to over 15-percent solids. The dried sludge is then hauled off-site and disposed in the Al-Ekeder landfill.When drying bed capacity becomes limited, thickened sludge is pumped into tanker trucksand hauled directly to a landfill.


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3.3.1.3 Shallalah WWTPThe Shallalah WWTP near Irbid city has been in operation since 2014, and was designed and built with German technical assistance. This facility has anaerobic digestion that generates biogas that is burned in engines to generate electricity to partially power the WWTP. The electricity generated by the biogas systems is reported to provide approximately 36 percent of the plant’s power requirement, significantly offsetting the electrical utility bill, but the maintenance effort and cost of the system is high.

The Shallalah WWTP includes primary sedimentation tanks to provide more sludge feed to the anaerobic digesters, as well as secondary clarifier tanks following aeration tanks. Additionally, the facility headworks includes a large screening and grit removal system to capture grit that might otherwise accumulate in the digesters. A summary of the process stream at Shallalah WWTP is as follows:

Liquid stream: Headworks (course and fine screens and grit removal) – PrimarySedimentation – Aeration (modified oxidation tanks) – Secondary Clarifier – rotatingbiofilm contact – UV disinfection – pump effluent to Jordan valley

Solids stream: Sludge storage – feed to digester (with ferric chloride addition) –anaerobic digestion – mechanical sludge thickening – mechanical sludge dewatering –truck solids to landfill

Biogas stream: Anaerobic digester – granular media (sulfide) scrubber – condensation –biogas generators gas storage – flare.

As of October 2018, the UV disinfection system was not operating well and was taken off-line. In addition, the biogas storage tank was taken off-line for repairs and only one biogas generator was operating. Additionally, GIZ provided a full-time technical expert (from Germany) to assist the plant staff with operating the biogas system.

3.3.2 Sludge Reuse ConsiderationsAs previously mentioned, there are three classes of sludge as defined by sludge quality and required biosolids treatment; however, both first- and second-class biosolids have the same disposal limitation and solids from WWTP cannot be used on agricultural lands. No sludge (biosolid) reuse options were identified by the Madaba Water and Biosolids Reuse Study in Appendix A; all biosolids will be landfilled in accordance with current Jordanian regulations and practices.

3.4 Jordan Air Emission Discharge StandardThe Jordanian Standard concerned with determining the maximum allowable limits of air pollutants from a stationary source is JS 1189/2006. This Jordanian Standard defines air pollutants as: Any material or substances entering the air and causing a change in its natural properties over a period of time and in quantities that lead to the occurrence of harm to human, animal, plant, or property, or affects the human enjoyment of life and property.

The same standard defines fixed sources as: Facilities, buildings, activities, and fixed operations that emit air pollutants through their chimneys.

3.4.1 RequirementsGeneral requirements of JS 1189/2006 are summarized as follows:


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The chimney height will be adequate to ensure that the contaminants are discharged into the outside air so that they do not cause overflow maximum limits of contaminants stipulated in Jordanian standard JS 1140:2006.

Dark smoke resulting from incineration operations will not be allowed to be equal to or greater than 1 Ringelmann (20-percent opacity).

The concentration of the total emitted particles will not exceed the maximum limits (shown in Table 3-5) when emitted from fixed stack sources in the following activities:

The overrun time will not exceed 5 percent of the operating time for daily operating units.

The concentration of pollutants from gases and vapors will not exceed the maximum limits indicated in the Table 3-6.

Table 3-5 Maximum Allowable Limits for Total Particulate Emission from Stationary Sources

Type of ActivityMaximum

Emission Limitmg/m³

Cement Industry 50Phosphate industry or industries that produce phosphate fumes and fertilizers 50Petroleum and petroleum refining industries 50Manufacture of casting and extraction of lead, zinc, or copper 20Other nonferrous metals casting industries 50Ferrous industries 50Boilers used for steam and power generation for industrial purposes 50

Table 3-6 Maximum Emission Limits for Gases and Vapors

ContaminantsMaximum

Emission Limitmg/m³

Sulfur dioxide (SO2) produced from:> Burning petroleum derivatives> Nonferrous industries> Sulfuric acid industries

6,5003,0001,500

Sulfur trioxide and sulfuric acid spray 150Nitrogen oxides (NOx) calculated on the basis of (NO2)

> Resulting from incineration processes with burning less than 1200°C> Resulting from incineration processes with burning more than 1200°C> Resulting from nonburning industrial processes

2001,500300

Volatile organic compounds 20Lead (Pb) 0.5Lead compounds 20Cadmium (Cd) 0.05Cadmium compounds 10

Note: Greenhouse gas emissions are not addressed by JS 1189/2006; therefore, international best engineering practices will be adopted to the extent practical for Jordan.


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3.4.2 Air Emission Limits at WWTPAir emissions at a wastewater treatment plant, from sources other than vehicles, include the combustion burning of biogas from anaerobic digestion and diesel standby generators.

3.4.2.1 Biogas electricity generation and flaringAnaerobic digestion-produced biogas is methane (CH4), and methane has 25 times more global warming potential than carbon dioxide (CO2). To prevent the digester-produced methane from escaping and adding to the greenhouse gas load, it should be burned to reduce it to carbon dioxide and water.

Jordanian Standard JS 1189/2006 activity type most applicable to the combustion of biogas generated at a WWTP is “Boilers Used for Steam and Power Generation for Industrial Purposes” with the maximum allowable total particulate emission of 50 mg/m3 and the maximum emission limits for gases and vapors listed in Table 3-6.

3.4.2.2 Diesel generators for standby powerIt is not clear if there is an air emission limit for stationary standby power diesel generators. Until this is furthered clarified, it is presumed that the standard mentioned above for biogas comparison will apply.

3.4.2.3 Gasification of biosolidsGasification of biosolids (sludge) is under consideration as an option for power or thermal generation. If such technology is utilized in full scale, the biogas electricity generation and flaring emission limits would apply.

3.5 Energy Efficiency and Renewable Energy PolicyIn 2016, the Ministry of Water and Irrigation (MWI) issued the “Energy Efficiency and Renewable Energy in the Water Sector Policy” as an integral part of the National Water Strategy. This policy mandates to improve the performance of the water sector through:

Improving the energy efficiency in water facilities to decrease the specific power consumption for water supply

Introducing renewable energy technologies to protect the environment and reduce energy price volatilities in the water sector

The energy targets of MWI for the year 2025 are specifically:

Reducing the overall energy consumption in public water facilities by 15 percent

Increasing the share of renewable energy to 10 percent of the overall power supply

3.5.1 Policy Targets until 2025 Fifteen-percent reduction in the specific energy consumption of billed water

corresponding to a 0.47 kg reduction of CO2 emissions for the production per each billed cubic meter of water.


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Raise the share of renewable energy resources in power consumption to 10 percent, corresponding to a total saving of 0.31 kg of CO2 emissions per each billed cubic meter of water.

3.5.1.1 The Policy PillarsThe two policy pillars to meet the target are:

Optimization and rehabilitation of water infrastructure

Introduction of economic feasible and environmentally friendly power generation system based on renewable energy resources

3.5.1.2 Optimization and Rehabilitation of Water InfrastructureThe water supply infrastructure consists of well fields, pumping stations, main transmission lines, water and wastewater treatment plants, water distribution, and wastewater collection networks. In the rehabilitation phase (depending on their state, power needs, and operational efficiencies), different water facilities should be rehabilitated according to a priority plan. Rehabilitation works of water pumping facilities will lead to reduction of power demand for pumping and pressure drop in the network and should achieve better water planning. These actions include mainly:

Replacement and/or repair of malfunctioned or damaged equipment

Replacement and/or repair of broken and/or leaking parts and pipes

Deployment of hydraulic modelling techniques in the water distribution network to employ gravity for water distribution to consumers

Proper maintenance of the facility buildings

The continued optimization and rehabilitation works will ensure the sustainability of the operation and maintenance of the water supply facilities. According to this policy, the following plans will be implemented to this objective:

Improving and extending the Supervisory Control Data Acquisition (SCADA) system coverage to include all water facilities, thereby enhancing water demand management, optimizing equipment utilization, and improving the water supply system.

Prepare routines for preventive and corrective maintenance plans for improving the operational efficiency of water facilities.

Human factor plays a significant role in promoting energy efficiency in the water sector. Therefore, highly qualified O&M personnel will be trained to operate technologically advanced control systems for the water system.

Adequate capacity-building programs will be designed to prepare O&M personnel at various water facilities for performing various tasks at different levels (highly qualified and ordinary workers) in accordance with best O&M practices.

Operational plan for the transportation fleet in the water sector will be implemented to control vehicle usage, thereby reducing fossil fuels consumption and avoiding inefficient use and abuse of vehicles.


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Engagement of the private sector mainly through Energy Performance Contracts between energy service companies and the water authorities, i.e., WAJ and JVA.

This will help allocate risks and ensure the quality of the product at fixed costs. The private sector roles are seen in:

Improving energy efficiency through systematic rehabilitation

Operation and maintenance works

Investing and bringing in new technologies that will foster future benefits

Health and Safety (H&S) plan should be prepared to ensure the safety of workers at the various facilities.

Security strategy should be developed, and plans should be prepared to secure facilities and to protect the whole system from vandalism, especially theft of water and equipment.

3.5.1.3 Economic Feasible Power Generation System This is the “introduction of economic feasible and environmentally friendly power generation system based on renewable energy resources” guidelines. The water sector promotes the introduction of renewable energy technologies into the sector within the framework of the national energy strategy to diversify energy resources and to reduce reliance on energy imports. In this context, the following policy statements are valid and the water sector provides:

Direct investments in renewable energy by the sector to supply a share of 10 percent of its power requirements from renewable energy systems by 2025.

Implementation of photovoltaic (PV) technology to supply the largest share of power to the water sector. Net-metering, wheeling mechanisms, and direct proposal can be used.

Establishment of hydropower stations at water dams and canals that have the potential to supply power at an economic rate.

Utilization of sludge from wastewater treatment as a biological power source to cover part of the energy needs of wastewater treatment facilities.

Introduction of wind energy farms and other renewable technologies, such as concentrating solar power (CSP), to supply power at economic rates.

3.5.2 Project Objectives of the Energy Efficiency and Renewable EnergyThe primary objective of the USAID Jordan Water Infrastructure Tasks 4 and 5 is the design of effective and resilient wastewater treatment facilities. To this end, energy efficiency is integral to a sustainable facility while achieving the effluent quality requirements via a facility this is easy to operate and maintain. Renewable energy is not an objective of Tasks 4 and 5, while photovoltaic (PV) and wind energy technologies are considered under Task 9. However, renewable energies that are derived from the perspective of wastewater treatment processes will be considered, such as the production of biogas from anaerobic digestion of sludge, if it is considered to be sustainable.


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3.5.3 Energy Sector Strategy 2020 - 2030The Ministry of Energy and Mining Resources issued its Energy Sector Strategy 2020 – 2030 in July 2020 and includes water sector strategy:

The energy efficiency of the water sector will increase by 15 percent in 2025 compared to 2018

Reduction of carbon emission by 10 percent

Increase local renewable energy sources from 11 percent to 14 percent by 2030


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Section 4Existing WWTP Condition Assessment

4.1 Condition Assessment TaskA feasibility study, design, and tender documents for the plant expansion are to be prepared Under Task 4 of the Madaba WWTP expansion of the USAID Jordan Water Infrastructure project. The first step was the completion of the Madaba WWTP condition assessment report that fulfilled several of the requirements listed in the Task Order Section C, Clauses 4.4 and 4.10.3, Feasibility Studies and Environmental Impact Assessments, and is a precursor report to the feasibility study. Work on the Madaba WWTP condition assessment report began in August 2018.

The condition assessment report assessed the condition of major treatment and unit processes and their associated equipment for the existing plant treatment operations and infrastructure and provides an opinion on what existing infrastructure could be reused for the WWTP expansion. Additionally, it provides recommendations for improvement of the current facility O&M and effluent quality. The objectives of this report were to (1) look at each major treatment process and equipment unit to document functional and nonfunctional status and assess existing O&M practices at the WWTP and (2) identify plant assets that could be reused or integrated into the design for the plant expansion.

The plant condition assessment study included the following activities:

Condition assessment site visit by a team of CDM Smith engineers and a senior WWTP operator on September 4–5, 2018.

Review of existing record drawings and reports for the WWTP.

Discussions with WAJ and Jordan Water Company-Miyahuna staff, as well as plant operation staff.

Two-week water sampling program and laboratory analysis in October–November 2018.

The MWI/WAJ and MWC letter dated October 31, 2019 with comments that are relevant to the feasibility study but not to the existing WWTP condition assessment report.

4.1.1 BackgroundThe Madaba WWTP original plant was a lagoon-based treatment system built in the 1980s. The plant was expanded and updated to an extended aeration activated sludge treatment system that became fully operational in 2002 (referred to as the 2002 Plant Expansion).

The plant was expanded and upgraded to have a BOD5 annual average daily load (AADL) of 7,220 kg/d and AADF of 7,600 m3/d secondary treatment configured as a BNR process to achieve organic matter, nitrogen, and phosphorus removal, with extended aeration tanks and secondary clarifiers (settling tanks). Additionally, new plant inlet headworks and sludge

Section 4 Existing WWTP Condition Assessment

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handling systems (thickener and drying beds) were added. In 2018, the dry weather average influent flow of 7,871 m3/d exceeded the 7,600 m3/d design capacity. It is thought that the actual exceedance is much higher than this value because, typically, the flow is recorded only a few times each day, a practice that misses the diurnal flow variation into the plant, so the actual flow could be higher. Additionally, the flow measurement device is often off-line for maintenance, which could contribute to the difference.

4.2 Condition Assessment Summary4.2.1 Plant Treatment PerformanceThe WWTP receives wastewater from the Madaba city sewer collection network and septage from local haulers. In 2018, the estimated average month influent flow was 7,530 m3/d and average dry weather (May–October) flow was 7,871 m3/d, with the maximum month flow (estimated) of 8,311 m3/d occurring in August. 2018 flow for the month of August is an estimate based on the ratio between 2017 monthly and annual flow. The existing WWTP’s design capacity is an average dry weather flow of 7,600 m3/d, and the WWTP is operating beyond the design capacity for the biological treatment processes.

The influent BOD5 measured during the sampling program in November 2018 averaged 768 mg/l, which was less than the design average influent BOD5 of 950 mg/l. The settling tank effluent BOD5 averaged 31 mg/l during the sampling, which exceeds the design average tank effluent BOD5 value of 20 mg/l. TSS measured in the influent during the same period averaged 644 mg/l, which was lower than the design average influent for TSS of 1,000 mg/l. The settling tank effluent TSS averaged 57 mg/l during the sampling, well above the design criteria of 30 mg/l.

The filtered settling tank effluent BOD5 measured during sampling averaged 5.4 mg/l and, as previously discussed, the settling tank effluent BOD5 averaged 31 mg/l. The settling tank effluent BOD5 was impacted by the high effluent TSS.

The plant effluent is not meeting effluent discharge standards for irrigation of cooked vegetables (Category 3[A]) JS893/2006 for effluent total nitrogen and E. coli, primarily because the plant is unable to nitrify and the effluent is not chlorinated.

4.2.2 Plant InfrastructureThe 2002 Plant Expansion unit process mechanical equipment and much of the electrical equipment is degraded because of age (installed in 2002) and insufficient maintenance, and it will require replacement or major overhaul. However, the concrete structures from the 2002 Plant Expansion were well constructed and remain in good condition and should be reused/repurposed if they are suitable for the proposed process design of the future plant expansion.

The WWTP infrastructure remaining from the original 1980s construction has exceeded its useful design life and will require complete rehabilitation if it is to be reused in a future plant expansion.

The treatment unit process condition assessment is discussed in the condition assessment report, and recommendations for the reuse of existing plant infrastructure are summarized in in that report. Additionally, a summary table of the recommended minor improvements is provided in the condition assessment report.


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The WWTP electrical and mechanical systems are degraded from time, exposure, and insufficient maintenance, while the process concrete structures are in good condition and have years of useful life remaining, assuming there is no excess deterioration of the concrete below the waterline. However, the ability to reuse the existing process structure as a treatment unit is limited by the ability to modify the structure for the new process requirements.

4.2.3 Operations and Maintenance ManagementThe MWC operates the WWTP. Although the plant appears to be well staffed with operations, laboratory, and mechanic technicians and laborers, the staff is not always available to work on the plant site (some staff are required to work on the collection network). Additionally, the plant O&M staff lacks the training, materials, and supplies necessary to perform their duties efficiently. Plant treatment performance could be improved through additional technical training, and energy usage could be decreased through better management of the plant’s surface aerators.


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Section 5Assessment of Treatment Technologies

This section reviews different treatment technologies under consideration for the expansion of the existing Madaba WWTP.

5.1 Introduction

5.1.1 How This Section is OrganizedThis section initially discusses the wastewater treatment process technologies and identifies suitable alternatives for the expansion of the Madaba WWTP for liquid-stream treatment in Section 5.2 and solids stream (sludge) in Section 5.3. Screening of alternatives, including criteria, is discussed in Section 7 along with liquid/solid-stream treatment technology alternatives and recommendations.

The second part of Section 5 discusses options for unit processes within the treatment plant that are not considered in the evaluation of liquid/solid-stream process evaluation, but are still essential for efficient plant operations.

5.1.2 ObjectivesAs discussed in previous sections, to treat the projected wastewater flow through the year 2045, new or upgraded wastewater treatment processes need to be selected to replace the existing processes. This process should provide for nitrification/denitrification and produce an effluent that meets the JS for effluent discharge (See Section 3). Methods of treatment for removal of contaminants is accomplished through chemical or biological reactions known as unit processes.

The following discussion further elaborates on each treatment process and options within each process that were considered for treating projected wastewater in Madaba District as described in Section 2.1.

Process flow diagrams and site layout plan drawings were prepared for each short-listed treatment alternative combination and are in Appendix D Feasibility Study Drawings. The individual drawings in this set are referenced by their drawing number.

5.2 Wastewater Liquid Stream Treatment TechnologiesWastewater liquid-stream secondary treatment processes are used to convert the dissolved organic matter in wastewater into settleable biological and inorganic solids that can be removed in secondary clarifiers. The process is also used for BNR. The following discussion identifies options for secondary treatment for this plant expansion.

Several of the following wastewater liquid-stream treatment alternatives are preceded with primary sedimentation (with primary clarifiers). The objective to including primary sedimentation with some of the liquid-stream treatment alternatives is to reduce the TSS and BOD5 loads, thereby reducing the energy required by the aerobic processes. The reduced loads in the primary effluent also allow for the reduction in size of liquid-stream treatment

Section 5 Assessment of Treatment Technologies

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processes, such as basin volumes and aeration system sizing. A disadvantage of primary sedimentation is that it produces a large quantity of sludge that must be treated, but this sludge can be treated using much less energy via anaerobic processes.

Primary sedimentation and options for primary clarifiers will be discussed later in this section after the discussion of the main liquid/solid-stream treatment alternatives. Chemically enhanced primary sedimentation is not evaluated because of the operational costs for the chemical addition and additional operational complexity.

Plug flow reactors with fine-bubble-diffused aeration and oxidation ditches are evaluated for the expansion. Because nitrogen and phosphorus removal is required, these two types of reactor configurations were evaluated as a five-stage Bardenpho BNR process.

5.2.1 Plug Flow Reactors with Diffused AerationPlug flow reactors equipped with fine-bubble-diffused aeration is the first alternative evaluated in this FS. Plug flow reactors consisting of rectangular basins and multiple basins in series may be used. By addition of a pre-anoxic zone and internal recycle flow, nitrogen removal can be achieved. Figure 5-1 presents Modified Ludzack-Ettinger (MLE) that can achieve complete nitrogen removal via nitrification and denitrification. Post-anoxic zone and reaeration zone can be added after the plug flow reactors to achieve lower effluent nitrogen concentrations. This process is called five-stage Bardenpho. Microorganisms referred to as mixed liquor suspended solids (MLSS) convert the organic matter (i.e., BOD5) into new biomass, carbon dioxide, and water in the aeration basins. The activated sludge is then settled out (separated from the treated wastewater) in final settling tanks (secondary clarifiers). Treated effluent from the secondary clarifiers needs to be disinfected while settled biological solids are pumped back to the aeration basins as RAS. A portion of the RAS is pumped to thickening and other solids treatment and handling processes as WAS.

An important part of this alternative is the aeration system, which consists of air blowers and diffusers used to supply oxygen. Fine-bubble air diffusers and multistage centrifugal blowers are widely used aeration technologies. To increase the energy efficiency, newer technologies, such as ultra-fine-bubble diffusers and high-speed turbo blowers, can also be considered. Anaerobic and anoxic zones before the aeration zones before plug flow reactors also serve as selector zones to lower sludge volume index (SVI) to maintain better settling sludge. Important design choices include the geometrical shape (rectangular or circular) of the secondary clarifiers, aeration basin side water depth (SWD), and MLSS concentration. For BNR, other criteria to consider are the solids retention time (SRT), hydraulic retention time (HRT), the secondary clarifier solids loading rate (SLR), and hydraulic overflow rate (HOR). Table 5-1 presents typical advantages and disadvantages of BNR activated sludge.


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Figure 5-1Process Schematic of a Modified Ludzack-Ettinger MLE Process with Plug Flow Reactors

Table 5-1 BNR Activated Sludge Advantages and Disadvantages

Advantages Disadvantages

Proven technology Low odor potential Ability to add anaerobic and anoxic zones to

configure as a BNR process to achieve nutrient(N and P) removal

Produces low turbidity effluent Flexible operation

More advanced process (aeration) controlrequired

Susceptible to shock influent loading Requires large recycle flows (IR and RAS)

5.2.2 Oxidation Ditch with Fine Bubble AerationOxidation ditch is a type of suspended-growth activated sludge system in which mixed liquor is pumped around an oval racetrack. Originally, surface aerators and brush rotors were used for mixing and pumping the mixed liquor, which limited the depth of oxidation ditches to approximately 3 meters. However, more efficient aeration methods using external blowers and fine-bubble diffusers have become more common, thus allowing ditches to be up to 6 meters deep. In this configuration, large propellers are used to pump the mixed liquor around the racetrack and keep it in suspension zones that are not aerated. Oxidation ditches are common in Jordan and used at the East Jerash and Shallalah WWTPs. Oxidation ditches can fully nitrify because they are typically designed for long SRTs in the range of 10 to 30 days (i.e., extended aeration process). However, shorter SRTs can also be used for oxidation ditches. The proposed aerobic SRT for the evaluated oxidation ditch for Madaba is 10 days. Longer aerobic SRTs require larger treatment tanks and if anaerobic digestion is planned, it is more cost effective to stabilize activated sludge in the anaerobic digester compared to equivalent stabilization in the aerobic process. Oxidation ditches can achieve simultaneous nitrification/denitrification as a result of the varying dissolved oxygen levels between aerated and nonaerated zones. With the addition of anoxic zones, an oxidation ditch can be operated as an MLE process to achieve denitrification. With the addition of anaerobic and post-anoxic basins (outside of the racetrack), the process can also be configured to achieve both nitrogen and phosphorus removal, such as five-stage Bardenpho. City of Fort Myers (Florida, USA) has two WWTPs that use the five-stage Bardenpho process with aeration basins configured as oxidation ditches. These plants were designed to reduce effluent TN below 3 mg/l and TP


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below 0.5 mg/l. These are much more stringent effluent nutrient limits then the proposed effluent nutrient limits for the Madaba WWTP. The East Jerash oxidation ditches are also equipped with external blowers, diffused aeration systems, and submersible mixers.

In an oxidation ditch, flow is continuously moving in a circular motion around these tanks as influent is fed and effluent is diverted off. A typical oxidation ditch process flow schematic is shown in Figure 5-2.

Figure 5-2Typical Oxidation Ditch Process Schematic

An oxidation ditch can be operated as an extended aeration process to generate less overall sludge and provide good buffering for peak flows and variations in loading. However, because of the long sludge age required for extended aeration, a larger tank is required compared to conventional activated sludge.

Oxidation ditches can also be operated as a conventional activated sludge process with shorter solids retention times and tankage that is similar in size to plug flow reactors when fine-bubble aeration is used to allow for deeper tanks. With an upstream anaerobic zone, an integrated anoxic zone, and a downstream post-anoxic zone, the oxidation ditch can be configured as a 5-stage Bardenpho treatment process producing the same effluent quality as a plug flow system. Oxidation ditches designed for nutrient removal are similar in operational complexity but are not as flexible for fine tuning because there are no discreet zones where the amount of aeration can be fine-tuned and the internal recycle flow is not adjustable because it is not part of an oxidation ditch designed for nutrient removal. Operational costs are very similar to plug flow systems with external blowers and fine-bubble diffusers in deep tanks.

Table 5-2 presents a comparison of the advantages and disadvantages of the oxidation ditch activated sludge process.


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Table 5-2 Advantages and Disadvantages of Oxidation Ditches


Excellent effluent quality Technology already used in Jordan; WWTP

operators have familiarity with the process Simple operational requirements Can provide simultaneous

nitrification/denitrification Proven technology Internal recycle pumps can be eliminated with

certain type oxidation ditches

Design of system is typically provided by anequipment manufacturer and needs to bereviewed in detail by engineer to provide bestsystem for specific project requirements andgoals

Construction can be more difficult because ofrounded walls

Not as easily expandable

One of the advantages that is offered by an oxidation ditch designed for nutrient removal is the elimination of internal recycle pumps. In these oxidation ditches, internal recycle flows back to the anoxic zone with the momentum of the mixed liquor flowing around the ditch and pumping is not needed. Instead, the oxidation ditch uses submerged mixers to keep the mixed liquor moving. The internal recycle pumps and the oxidation ditch mixers both have relatively small motors compared to the total energy requirement, so this distinction should not be a deciding factor.

5.2.3 Sequencing Batch ReactorThe sequencing batch reactor (SBR) is a fill-and-draw activated sludge system for biological treatment. Figure 5-3 provides a simplified schematic of the SBR process. In this system, wastewater is added to a batch reactor, in which equalization, aeration, and clarification steps of activated sludge process can be achieved in a single complete mix reactor. To maintain continuous flow, at least two batch reactors are used in a predetermined sequence of operations. SBRs are typically used at flow rates of 19,000 m3/d or less and often prove to be a relatively low-cost biological treatment alternative for small facilities.

Figure 5-3Sequencing batch reactor schematic

The fill-and-draw principle consists of six steps—mixed fill, aerated fill, react, settle, decant, and idle—as discussed in the following:

Mixed Fill – Wastewater enters a partially filled reactor containing biomass. Bacteriabiologically degrade the organics and use oxygen or alternative electron acceptors, such


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as nitrate. It is during this period that anoxic conditions are utilized for the selection of biomass with better settling characteristics.

Aerated Fill – Influent flow continues under mixed and aerated conditions.

React – Influent flow is terminated and directed to the other batch reactor. Mixing and aeration continue in the absence of raw waste. BOD5 absorption and removal that was initialized during mixed and aerated fill is completed and nitrification can be achieved.

Settle – Aeration and mixing is discontinued after the biological reactions are complete and the biomass settles under quiescent conditions. Excess biomass can be wasted at any time during the cycle. The settle time is adjustable during operations to match prevailing process needs.

Decant – After solid/liquid separation is complete during the settle period, the treated effluent is removed through a decanter. The reactor is then ready to receive the next batch of raw influent.

Idle – Length of this step varies depending on the influent flow rate and the operating strategy.

A crucial feature of the SBR system is the control unit, including the automatic switches and valves that sequence and time the different operations. Because the heart of the SBR system is the controls, automatic valves, and automatic switches, these systems require more sophisticated maintenance than a conventional activated sludge system.

An important consideration for the SBR system is that the effluent only discharges intermittently and, therefore, will greatly affect the size of the downstream process units. The decant rate is substantially higher than the plant inflow, hence requiring either downstream equipment with large capacity or a post-equalization tank to even out the flow.

Advantages and disadvantages of the SBR activated sludge system are shown in Table 5-3.

Table 5-3 Sequencing Batch Reactor Advantages and Disadvantages


Small footprint because of common walls and the combination of react and settle in one tank (no need for clarifiers)

Less prone to toxicity shocks than plug flow reactors

Can achieve both N and P removal Proven technology

Higher operational complexity High decant rate necessitates oversizing

downstream process units or installing an equalization basin

Scheduling of maintenance is more difficult because the tanks cannot be easily taken completely off-line

Little process knowledge in Jordan Cold weather and freezing become

problematic

5.2.4 Other Liquid Stream Treatment ProcessTable 5-4 is a list of liquid-stream wastewater treatment processes and technologies that were considered but not short-listed for the reasons indicated. Although these technologies may have advantages that are well suited to the Jordan condition, overall, they did not compare in the opinion of the core design team.


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Table 5-4 Liquid Stream Treatment Technologies Not Short-Listed

Liquid Stream Treatment Technology Reasons Not Short-Listed

Land-based treatment (construction wetlands)

Insufficient land available for technology Public and WAJ opposition to technology

Multicell aerated lagoon and anaerobic lagoon systems

Public and WAJ opposition to technology because of past failures High land requirement

Upflow anaerobic sludge blanket (UASB)

Complex process not currently used in Jordan Large tank volume requirements

Trickling filter or trickling filter with solids contact tank

Would not meet effluent standard for phosphorus Public and WAJ opposition to technology because of past failures

Aerobic granular sludge (AGS) New technology with potentially complete operation Proprietary technology

5.2.5 Phosphorus Removal Methods and RecommendationThe Jordanian discharge (reuse) standard for PO4-P (ortho-P) is 9.8 mg/l and the historical average influent PO4-P concentration at the Madaba WWTP is 15 mg/l. The effluent ortho-P limit is not stringent, but phosphorus removal is still required to meet the standard.

Phosphorus removal can be achieved with enhanced biological phosphorus removal (EBPR) or chemical precipitation with metal salt addition, such as alum. The metal salts can be added at multiple points in the process, including primary influent and effluent, and before secondary clarifiers. Chemical addition is a relatively simple process while the EBPR requires more attention.

For chemical phosphorus removal, a metal salt, such as ferric chloride, is added to the primary clarifiers to provide chemically enhanced primary treatment (CEPT). The flocculent will precipitate ortho-P and settle it out for removal with the primary sludge. Alternatively, ferric chloride can be added to the mixed liquor to precipitate ortho-P. The precipitated ortho-P is then removed from the process with WAS.

EBPR is a straightforward process and requires additional anaerobic tanks before denitrification. There are other innovative and fairly new technologies that are not being considered because they strive for effluent TP less than 1.0 mg/l. Sidestream EBPR is an example that is configured to generate volatile fatty acids needed for EBPR via fermentation of RAS in a sidestream tank rather than relying on volatile fatty acids present in the influent wastewater.

EBPR is a more viable phosphorus removal method for the WWTP expansion because it is fairly straight forward and eliminates the chemical need. Chemical addition will increase O&M cost and sludge generated. Therefore, for the alternatives being considered in Section 6, five-stage Bardenpho process will be included for phosphorus removal. Five-stage Bardenpho is a BNR process that can achieve both nitrogen and phosphorus removal.

5.2.6 Liquid Stream Treatment AlternativesThree liquid-stream treatment process options were evaluated that included the consideration for primary sedimentation (primary clarifiers) ahead of two treatment process options for a total of five liquid-stream treatment options evaluated. Those options with


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primary sedimentation were grouped into alternatives with anaerobic solids digester because anaerobic digestion is more economical and produces more digester gas when fed primary sludge.

Except for SBR, which does not require separate secondary clarifiers, the alternatives of the treatment process options all assume the same headworks system, treated effluent disinfection, and secondary clarifiers. The liquid-stream treatment alternatives are as follows:

Alternative A – Modification of existing process tanks to BNR with primary clarifiers and addition of a new BNR train

Alternative B – OD with primary clarifiers

Alternative C – BNR with primary clarifiers

Alternative D – Not Used

Alternative E – BNR without primary clarifiers

Alternative F – SBR

5.2.6.1 Alternative A – Modify Existing Aeration TanksThis alternative is the modification of the existing two aeration trains to BNR (five-stage Bardenpho with plug flow reactors) process with primary clarifiers, and add two new trains for a total of four parallel treatment trains of 4,000 m3/d each for a total plant average capacity of 16,000 m3/d. The existing secondary clarifiers are not configured to current clarifier standards and will be replaced with new larger secondary clarifiers. The two existing aeration train tanks would be modified by adding anerobic and anoxic zones on up-front, post-anoxic, and reaeration at the end of each train.

Alternative A process flow diagram is Drawing No. M-MA-1 and the site plan is Drawing No. C-MA-1; this site plan also shows the site layout for solids stream Alternative 1 conventional anaerobic digestion with CHP system.

This alternative includes the following:

Installation of new primary clarifiers

Installation of one new BNR train (structural, mechanical, and electrical) parallel to the existing aeration tanks

Installation of anerobic and pre-anoxic zones in the front of the existing aeration tanks

Partition post-anoxic and reaeration zones (tanks) in the end of the existing aeration tanks

Replace mechanical and electrical equipment in the existing tanks and make structural upgrades

Retrofit existing aeration tanks with fine-bubble diffusers, instead of replacing the surface aerators

Demolish the existing secondary clarifiers


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Installation of new secondary clarifiers

Installation of new primary, RAS, and WAS pump stations and piping

One year longer construction time than the other alternatives owing to staging necessary to keep the plant operational during construction

Solids (sludge) stream treatment options for Alternative A are:

Alternative 1 Conventional Anaerobic Digestion,

Alternative 2 CIGAR

Alternative 3 Aerated Sludge Holding Tank

Sludge dewatering for all alternatives is both drying beds and mechanical dewatering because the drying beds are not enough during the winter months.

5.2.6.1.1 Construction Sequencing Considerations The new third treatment train would be built first and placed into operation. Once the third train is operational, the existing aeration tanks would be taken off-line and rehabilitated/upgraded.

5.2.6.2 Alternative B – Oxidation Ditch with Primary ClarifiersThis alternative cancels the existing aeration and secondary clarifiers and replaces them with a new OD BNR (five-stage Bardenpho) and primary clarifier system. There would be four liquid treatment trains of 4,000 m3/d each for a total average plant capacity of 16,000 m3/d.

Alternative B process flow diagram is Drawing No. M-MA-02 and the site plan is Drawing No. C-MA-02.



Installation of oxidation ditch system with four trains complete

Installation of four new secondary clarifiers


Decommissioning of existing process tanks

Solids (sludge) stream treatment options for Alternative B are:

Alternative 1 Conventional Anaerobic Digestion

Alternative 2 CIGAR




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5.2.6.2.1 How Plant Operations Would be Maintained The new treatment tanks would be built parallel to the existing tanks while the existing plant remains in service. Once the new plant is built and commissioned, the existing treatment trains would be decommissioned.

5.2.6.3 Alternative C – Biological Nutrient Removal with Primary ClarifiersThis alternative cancels the existing aeration and secondary clarifiers and replaces them with a new BNR (five-stage Bardenpho with plug flow reactors) and primary clarifier system. There would be four liquid treatment trains of 4,000 m3/d each for a total average plant capacity of 16,000 m3/d.

Alternative C process flow diagram is Drawing No. M-MA-03 and the site plan is Drawing No. C-MA-03; this site plan also shows the site layout for solids stream Alternative 1 conventional anaerobic digestion with CHP system.



Installation of BNR system with four trains complete




Solids (sludge) stream treatment options for Alternative C are:

Alternative 1 Conventional Anaerobic Digestion

Alternative 2 CIGAR




5.2.6.4 Alternative D – Oxidation Ditches without Primary ClarifiersThis alternative cancels the existing aeration and secondary clarifiers and replaces them with a new OD BNR system with primary clarifiers. However, in the 2019 Expansion of Ramtha WWTP Feasibility Study Report, this alternative with surface aeration had significantly higher power requirements than the other alternative evaluated; but, when reconfigured to a submerged aeration system, the power requirements were similar to Alternative E. For this reason, Alternative D was not further evaluated in this study for the expansion of Madaba WWTP. No drawings for this alternative were prepared.


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5.2.6.5 Alternative E – Biological Nutrient Removal without Primary ClarifiersThis alternative cancels the existing aeration and secondary clarifiers and replaces them with a new BNR (five-stage Bardenpho with plug flow reactors) system without primary sedimentation. There would be four liquid treatment trains of 4,000 m3/d each for a total average plant capacity of 16,000 m3/d.

Alternative E process flow diagram is Drawing No. M-MA-04 and the site plan is Drawing No. C-MA-04; this site plan also shows the site layout for solids stream Alternative 4 aerobic sludge digestion.


Installation of BNR system with four trains complete; this system would be larger than the Alternative B tanks because they have a higher organic loading since there is no primary sedimentation


Installation of new RAS and WAS pump stations and piping


Solids (sludge) stream treatment options for Alternative E are:


Alternative 4 Aerobic Sludge Digestion



5.2.6.6 Alternative F – Sequencing Batch ReactorThis alternative cancels the existing aeration and replaces it with a new SBR system. However, SBR are not well suited to plants of this size and typically have operational issues, so it will not be considered further. No drawings for this alternative were prepared.

5.3 Wastewater Solids Stream Treatment TechnologiesWastewater solids or sludge treatment processes are used to stabilize and reduce the volume of particle (solid) organic matter in wastewater into safe organic and inorganic solids for off-site disposal of the remaining solids. Jordanian regulations and practices restrict the reuse of biosolids from WWTPs so that only landfill disposal is practical. Therefore, solids treatment only needs to achieve Third-Class Biosolids (see Section 3). The following discussion on solids treatment alternatives focuses on technologies that meet treatment objectives for volume reduction and dewatering with the goal of reducing truck hauling costs to the landfill.


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However, because of high interest by MWI/WAJ and the donor organization, energy recovery from sludge in the form of anaerobic digestion is also discussed.

The anaerobic digestion alternatives are only paired with liquid-stream treatment process alternatives that have primary sedimentation because the high organic content and volume of solids make anaerobic digestion more cost effective. The technologies discussed in this section are as follows:

Conventional anaerobic digestion (mesophilic) – stabilization and volume reduction

Covered in-ground anaerobic reactor – stabilization and volume reduction

Aerated sludge holding tank

Aerobic sludge digestion – stabilization and volume reduction

Drying beds sludge – dewatering

Lime stabilization – stabilization

Other solids stabilization, volume reduction, and dewatering options considered but not short-listed were composting, incineration, and gasification. These processes were not short-listed because of their public acceptability and low product reuse or high energy input.

Final disposal of all wastewater solids into a landfill is required by JS, as discussed in Section 3. Landfill of wastewater solids is the only practical disposal option according to JS. To reducethe volume of sludge hauling to the landfill all solids treatment alternatives will include solidsdewatering and a dry solids content of at least 20 percent. Because of seasonal limitation ofdrying bed performance and that most WWTPs in Jordan are limited in their solids capacity,all alternatives include mechanical solids dewatering as well as drying bed dewatering.

5.3.1 Conventional Anaerobic DigestionConventional anaerobic digestion has been practiced for decades and is one of the most common technologies used for stabilization (pathogen and odor reduction) of biosolids utilized around the industrialized world and can add significant operational complexity to the facility.

Conventional anaerobic digestion refers to single-stage, mesophilic, anaerobic digestion, where biosolids are heated to 35°C and mixed in a reactor with a solids-retention time of approximately 20 days at average conditions. Figure 5-4 shows a simple schematic of anaerobic digestion, including the recirculation of sludge for heating purposes. Within the reactor, chemical and biochemical reactions occur, including hydrolysis, fermentation (acidogenesis, or the biological formation of volatile fatty or organic acids), and methanogenesis (biological conversion of organic acids to methane and carbon dioxide).

During these processes, volatile solids reduction (VSR) occurs as volatile solids are biologically converted into gases and water. VSR during mesophilic digestion processes will vary based on retention time and feed sludge characteristics, but will typically range from 40 to 50 percent. The digester gas (biogas) produced has a methane content of approximately 60 percent and has the potential to be used for renewable energy in the form of renewable natural gas, electricity, and/or process heating (see Section 5.3.3).


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Figure 5-4Conventional Anaerobic Digestion Schematic

Advantages and disadvantages of conventional anaerobic digestion are shown in Table 5-5.

Table 5-5 Conventional Anaerobic Digestion Advantages and Disadvantages


Can have VSR of 40 to 50 percent Biogas can be converted into renewable

energy, lowering facility carbon footprint Generally beneficial lifecycle costs Less odor for solids handling processes

downstream Long standing technology

Relatively complex operations Relatively complex maintenance High capital cost Increase in nitrogen and phosphorus in

recycle stream Struvite formation

5.3.1.1 Components of Conventional Anaerobic DigestionConventional anaerobic digestion is more complex compared to other biosolids handling processes; therefore, it is important to understand the various components involved. Refer to Section 5.3.3 for a discussion of digester gas utilization technologies.

5.3.1.1.1 Sludge Pretreatment and ManagementCommon management strategies for the pretreatment of sludge and any received septage prior to feeding the digesters include the following:

Screening: To mitigate the quantity of stones, plastics, and other inert material fromaccumulating in the digester tanks, the primary sludge and any septage should passthrough an in-line pressurized screen prior to entering any thickening process or thedigesters.

Thickening: To increase the solids retention time in the digesters, primary sludge,WAS, and any septage should undergo thickening. Primary sludge, as well as rawseptage (which can have significant variability in solids concentration), can be


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thickened using gravity thickeners (discussed in more detail in Section 6.8), which utilize conventional sedimentation methods to collect sludge in a conical bottom of a circular tank; concentrations over 5-percent solids can be achieved for primary sludge. While gravity thickening can also be used for WAS, gravity belt thickening (discussed in more detail in Section 5.8) is often recommended because of its effectiveness for sludges with lower solids concentrations. Gravity belt thickeners (GBTs) utilize gravity belts and rollers to thicken sludge to 5- to 7-percent solids.

Uniform feed operation: Because anaerobic digestion uses biological processes, uniform feeding is critical. Sludges should be pumped continuously or on long cycle times to maintain consistency in the digesters. Thickened sludge pumps can operate on variable frequency drivers (VFDs) to aid in this operational scheme; however, maintaining minimum velocities to avoid sludge settling may require intermittent feeding at higher flows. Buffer tanks can also be included as necessary, such as holding tanks or blend tanks, for better control of the feed to the digesters. Gravity thickeners provide buffer capacity as well.

Chemical addition: Chemical addition, such as ferric chloride, is another form of pretreatment prior to the digesters. Ferric chloride is a precipitant that can help control hydrogen sulfide (H2S) and struvite within the sludge, as well as soluble phosphorus content in solids side stream. Ferric chloride will react with H2S first.

For the Madaba WWTP, each of these strategies is recommended for handling primary sludge, WAS, and septage, and to improve digester performance. Refer to Drawing No. M-MA-05 for the process flow diagram of the pretreatment processes. Note that a blend tank was not included upstream of the digesters, thus keeping primary sludge and WAS as separate as possible prior to digestion and to reduce the amount of phosphorus released back into the solids side stream. Without the blend tank, pumping operations between the different feed streams are critical to ensure a consistent feed of sludges.

5.3.1.1.2 Digester Tank ConfigurationsConventional anaerobic digester tanks are typically either cylindrical or egg-shaped, as described below:

Cylindrical tanks: These are widely used around the world and generally constructed of reinforced concrete with a conical bottom, with dimensions ranging 6–38 m in diameter and 7.5–15 m in height. Cylindrical concrete tanks are advantageous for their available volume to store gas, their ease in accessibility (i.e., roof access), and their relatively lower capital costs. On the other hand, insufficient mixing can result in grit accumulation, large surface areas can allow foam and scum formation, and cleaning may be required to remove grit, foam, and scum. Refer to Figure 5-5 for an example of a concrete cylinder tank.

Egg-shaped digesters: These are very popular in Europe and are gaining popularity in other regions of the globe. The egg-shape consists of a steeply sloped cone for improved mixing compared to traditional cylindrical tanks. Because of the complex forms needed for concrete, egg-shaped digesters are often constructed of steel (which may require insulation). Because of its enhanced mixing, grit accumulation and scum formation are minimized, which lowers operating and maintenance needs. While the footprint is much smaller, the structures are high-profile and difficult to access. Additionally, the egg-


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shape provides less gas storage volume and increases capital costs. Refer to Figure 5-5 for an example of an egg-shaped tank from RSB Formworks.

Figure 5-5Concrete Cylinder Digester Tank (Left) with Fixed Steel Cover (Ovivo) and Egg-Shaped Digester Tanks

For a smaller facility like Madaba WWTP, the traditional cylindrical tank is recommended for its cost effectiveness. From a maintenance perspective, the cylindrical tank would likely have greater cleaning requirements but, at the same time, the cylindrical tank would provide better accessibility to roof-mounted equipment (e.g., mixing and gas relief valves).

5.3.1.1.3 Digester Tank Cover ConfigurationsDigester covers must maintain anaerobic conditions in the tank, contain and assist in collecting biogas produced during the digester process, reduce odors, retain heat to maintain internal temperatures, and support some type of mixing equipment. For traditional cylindrical digesters, cover types can consist of floating, fixed, and gas membrane.

Floating covers: These covers are usually constructed of a metal framework andattached to the tank by placing tracks upon corbels within the tank. These tracks allowthe cover to float directly on the sludge surface, allowing for fluctuations of the liquidsludge level with minimal changes in biogas pressure. Floating covers have relativelyhigh capital costs compared to other cover types.

Fixed covers: Fixed concrete or steel covers have historically been the option with thelowest cost and least potential for operation and maintenance problems compared tofloating covers. Unlike floating covers, fixed covers do not allow for variation in volume,so any change in liquid volume would have a corresponding change in gas volume andpressure in the tank. Consequently, gas pressure must be controlled to prevent damageto the cover. These allow for less gas storage and less flexibility regarding sludge liquidlevel. See Figure 5-5 for an example of a fixed steel cover.

Gas membrane covers: These covers provide a large and variable volume of digestergas storage using a double-membrane design, with the outer membrane maintaining adome shape and the inner membrane moving up and down depending on gas storagerequirements. Ambient air fans and valves add or release air from the space betweenthe membranes to maintain the consistent dome shape and constant biogas pressure.Utilizing gas membranes does limit the amount of mixing equipment that can be used,and the membranes offer little insulating value.


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For Madaba WWTP, fixed steel digester covers are recommended primarily for their simplicity in both construction and operation, as well as their cost effectiveness. In addition, a separate gas storage holder could be provided to account for the smaller storage volume within fixed covers.

5.3.1.1.4 Digester Mixing SystemsDigester mixing is a crucial component to keep uniformity within the digester, prevent scum accumulation in the reactor, and maintain volatile solids reduction and biogas production performance. The most common mixing systems include recirculation pumps, compressed biogas, and mechanical mixing.

Pump mixing (recirculation pumps): Recirculation pump systems use externalpumps to recirculate the sludge for mixing. Sludge is pumped from the digester tankand is reintroduced through several ports located around the circumference of thedigester or discharged through nozzles. Depending on tank diameter, pumping ratestypically turn over the contents of the digester every 3 to 12 hours.

Gas mixing with compressed biogas: Compressed gas systems utilize a gascompressor to draw and compress biogas from the headspace of the digester anddistribute it into the sludge via multiple mixing devices. Different gas mixing systemsinclude discharged lances, floor-mounted diffusers, confined draft tubes, and “bubblegun” gas mixers. The first two types are unconfined, discharging gas through lances ordiffusers, while the latter two are confined, discharging gas through confined tubes orgas lifters.

Mechanical mixing: This type of mixing involves physical movement to agitate thecontents of the tank. Examples of mechanical mixing are bladed prop mixers or linearmotion plunger type mixers. A tank can have one or more mechanical mixers dependingon type and manufacturer, size of the tank, and amount of turnover needed.

While digester gas mixing would provide operational similarity to the Shallalah WWTP, the technology is complex to operate and has limited mixing capacity for thicker sludges; additionally, many systems are being phased out and replaced, and for these reasons, this method was eliminated from the evaluation.

A recirculation pump system, for its simplicity, is a good alternative, but its higher energy needs is a major disadvantage. Mechanical mixers, specifically linear motion, are low speed and have low energy needs. While generally simple and with low maintenance requirements, maintenance requirements do require access to the top of the tank. For linear motion mixers especially, the weight of the mixer must also be factored into the tank and cover structural design.

Tables 5-6 and 5-7 list advantages and disadvantages for recirculation and mechanical mixing, respectively.

Table 5-6 Recirculation Pump Mixing Advantages and Disadvantages


Pumps are external and easily accessible formaintenance

Lower capital cost

Higher energy consumption to run pumps Withdrawal pipe must penetrate tank walls


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Table 5-7 Mechanical Linear Motion Mixing Advantages and Disadvantages


Lower energy consumption Simple operation

Higher capital cost Maintenance requires access to top of the

tank

To evaluate the conventional anaerobic digestion alternative, linear motion mixing has been preliminarily selected; however, further analysis could be provided if this alternative is selected. For the digested sludge storage tank, however, recirculation mixing pumps are currently shown. Because of the lower volume and less turnover required, the energy consumption would be significantly less for the digesters.

5.3.1.1.5 Sludge Heating SystemsAnaerobic digesters are heated to maintain an environment conducive to methane-forming microorganisms and to ensure greases and fats within the digester remain in an emulsified state so they can be broken down biologically. There are two main types of heating systems: internal and external.

Internal: Within an internal arrangement, heat is applied to the sludge while it remainsin the digester tank. Older digester heating arrangements included mounting pipes tothe interior of the digester wall, through which hot water was circulated and draft tubemixers were equipped with hot-water jackets. These have become less popular due tooperational issues, including the buildup of sludge on the heating surface and accessrestrictions. Additionally, all internal heating systems rely on the digester mixingsystem to circulate heat within the digester, requiring the mixing to operate on acontinuous basis, creating a heat gradient and biologically inactive zones.

External: Newer digesters typically use external heating systems that recirculatesludge through external heat exchanger(s) and recirculation pumps. Feed sludge can bemixed with heated sludge prior to entering the digester, or the heat loop can operateindependently (separate feed and recirculation lines). Refer to Figure 5-6 for anexample of a commonly used sludge tube-in-tube heat exchanger.

Hot water for the digester heating system is usually supplied by either waste heat from a cogeneration system and/or a boiler that utilizes biogas from the anaerobic digester. Natural gas or propane can be used to supplement fuel, as required.

For the Madaba WWTP, external heating is recommended for these new digesters because the internal heating is outdated and has shown to cause operational issues.

Figure 5-6Sludge Tube-in-Tube Heat Exchanger (Wes-Tech)

5.3.1.1.6 Sludge Pumping and PipingFor thickened primary sludge, thickened WAS, and digested sludge, positive displacement pumps are generally used to better handle thicker sludges (> 3-percent solids). Progressive cavity pumps are commonly used, and these pumps move fluid through a series of cavities by


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turning a rotor. While progressive cavity pumps can handle suction lift under certain conditions, a flooded suction configuration is recommended for thicker sludges, requiring some pumps to be installed in a vault or basement depending on the tank liquid level and withdrawal operation. Rotary lobe pumps are another positive displacement pump that could be considered during final design.

5.3.1.1.7 Struvite ManagementFor this alternative, WAS would contain high levels of phosphorus from the five-stage Bardenpho process, presenting an increased risk of struvite formation in the pipes. Struvite (magnesium ammonium phosphate) precipitates out of the sludge and accumulates on the pipe, thus reducing the flow area of the pipe. Struvite deposits in the pipe can be mitigated with glass-lined pipes and avoidance of short-radius pipe bends that cause turbulence and encourage struvite formation. Additionally, as previously discussed, dosing ferric chloride to the sludge can be another option to manage struvite formation.

There are technologies that allow struvite to be harvested from the digester system and converted into an agricultural fertilizer. However, since Jordanian regulations restrict the use of solids from WWTP to be used on agricultural lands, there is no market for the product.

5.3.1.2 Other Heated Anaerobic TechnologiesAnaerobic solids stabilization options that were considered but not short-listed include thermal hydrolysis process (THP) and thermophilic anaerobic digestion. These processes were not short-listed because of their highly specialized and complex operations.

5.3.2 Covered In-Ground Anaerobic ReactorA CIGAR is a low-rate anaerobic digestion process. As in conventional anaerobic digestion, specialized bacteria achieve volatile suspended solids (VSS) destruction in primary and secondary sludge and release methane gas which can then be utilized for on-site electricity generation or sent to a combustion unit. A CIGAR can be a low-cost option implemented to treat primary and secondary sludges anaerobically.

There are two design options that are considered. CIGARs can be designed for continuous sludge removal to maintain a certain hydraulic retention time and a solids retention time for several years. Alternatively, CIGARS can also be designed to store the sludge long-term (i.e., 10 or 20 years) without any sludge removal if sufficient land is available.

Usually, CIGARs are comprised of two or more units connected in series. Sludge is added to the first unit and gravity flows to the downstream units. Baffles can be installed in reactors to prevent short-circuiting. The reactors operate anaerobically to maximize VSS destruction, methane production, and odor control. The final reactor can be designed to provide variable volume for the storage of the supernatant gravity flows from the upstream reactors. The supernatant is returned to the liquid treatment. Figure 5-7 presents an example plant process flow diagram using CIGARs.


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Figure 5-7Process Flow Diagram Covered In-Ground Anaerobic Reactor

CIGAR installations usually implement a flexible membrane bottom liner and cover. The purpose of the liner is to prevent leachate from contaminating the ground, groundwater, and aquifer systems, as well as prevent methane gas from escaping into the atmosphere. The system is only opened if accumulated solids must be removed. A CIGAR should be excavated to be as deep as geologic conditions will allow. This is more important for primary reactors because more depth is conducive to maintaining a temperature that promotes bacterial growth. Generally, the minimum depth for a primary reactor is 3.5 m. In addition, greater depth reduces the land requirement, which translates to a smaller cover. Smaller covers have the dual benefit of less capital cost and less stormwater to contend with. Table 5-8 summarizes the advantages and disadvantages of CIGARs.

Table 5-8 Covered In-Ground Anaerobic Reactor Advantages and Disadvantages


Low capital and O&M costs Possible combustion of biogas for heat or

electricity production Easier operation because no sludge removal Continuous sludge removal can be

implemented CHP system can be added in future

Larger land area requirement Cannot produce first-class biosolids Can be difficult to access sludge for removal in

the first cells (reactor) Low rate biogas production


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5.3.3 Digester Gas Utilization for Electricity GenerationThe use of biogas from anaerobic digestion is one of the most readily available, proven, and cost-effective sources of energy at wastewater facilities. Biogas production can range from 0.75 to 1 m3/kg of volatile solids reduced.

Generally comprised of 60-percent methane, biogas can be combusted to generate electricity using a biogas-fueled combined heat and power (CHP) engine generator. In addition to generating power, heat recovered from the engine can provide heat to the anaerobic digestion process, freeing up more biogas for alternative uses. Prior to utilization at the CHP engine, the biogas generally requires gas compression and treatment, including the removal of moisture, H2S, and siloxanes. Figure 5-8 shows a schematic of biogas utilization for energy and heating.

Table 5-9 presents digester gas utilization system advantages and disadvantages.

Table 5-9 Digester Gas Utilization System Advantages and Disadvantages


Utilization of biogas for renewable energy,lowering facility carbon footprint

Beneficial life cycle costs

Complex operations Complex maintenance High capital cost

Figure 5-8Digester Gas Utilization Schematic

5.3.3.1 Components of Digester Gas Utilization SystemLike the conventional anaerobic digestion system that generates the digester gas, the digester gas utilization system for CHP is also more complex with more components than other process systems, and needs to be understood to allow for an informed selection of alternatives.

MoistureRemoval


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5.3.3.1.1 Digester Gas Storage and HandlingGas handling consists of gas storage, flaring, conveyance, and safety equipment. The conveyance system brings biogas at the rate it is produced in the digesters to equipment for consumption, storage, or releasing (combustion prior to release to atmosphere), as discussed below:

Biogas Storage: Because biogas is not produced at a constant rate, nor is gas usage always constant, biogas storage can provide operational flexibility and maximize biogas capture rate, thus increasing the overall efficiency of the system. A double membrane gas holder is a common form of stand-alone gas storage. The exterior membrane is made from polyester fiber fabric and coated with polyvinyl chloride (PVC) that is UV, microbial, and abrasion resistant. The internal membrane is also typically manufactured from PVC-coated polyester fiber fabric, which is microbial, abrasion, and biogas resistant. Membrane covers have proven reliable, with a service life as high as 15 years for newer systems. System storage can provide 2 to 8 hours to ensure a high biogas utilization rate. Figure 5-9 shows an example of a membrane gas storage holder.

Waste Gas Burner: Including a flare or waste gas burner provides a safe and effective way to release excess gas from the digester gas utilization system. For example, if gas conditioning or CHP equipment requires maintenance, gas can be released safely via combustion at the waste gas burner. The waste gas burner blends pilot gas and air to obtain a high temperature pilot ignition used for the combustion of biogas. The burner can operate based on pressure to prevent over pressurization in the gas utilization system. Flares can be fully enclosed or open (“candlelit”). Fully enclosed flares have no visible flame and can provide lower nitrogen oxide (NOx) and carbon monoxide (CO) emissions. Open flares are a longstanding technology with simpler maintenance; thus, this type is recommended for the Madaba WWTP. Figure 5-9 shows an example of an open waste gas burner.

Conveyance: Most biogas conveyance systems are low pressure and operate at approximately 30 mbar or less. The piping is sized for relatively low velocities to minimize pressure losses in the system and maximize condensate removal at condensate traps. After gas conditioning, gas is compressed, as required, to operate the CHP engine or boiler (0.1–0.3 bar) and velocities can increase. The industry standard for biogas piping material is 316L stainless steel, though other materials are used.

Safety: Like natural gas, biogas is explosive at low concentrations of approximately 1 volume of gas to 15 volumes of ambient air. As such, it is important that the biogas handling system be fitted with appropriate gas-safety equipment to protect against the risk of ignition and a potentially catastrophic explosion. Any source of ignition, such as waste gas burners, engines, or boilers must be protected against flashback through the piping with a flame arrestor or flame traps. A flame arrestor works to quench the flame by dissipating any heat from a potential explosion in the piping. A flame trap is a combination of a flame arrestor and a thermal shutoff valve. If a propagating flame is stopped by the arrestor but continues to burn in the piping, a thermal element in the thermal shutoff valve will melt and seal off the remainder of the upstream piping from the fuel source.

Anaerobic digesters are provided with pressure/vacuum relief valves, typically mounted directly on top of the digester tank. These valves release any biogas to the


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atmosphere when the pressure rises above a setpoint to protect from over-pressurization of the tank. Additionally, a vacuum relief valve will allow entry of ambient air into the tank, during any vacuum conditions, to protect the tank from imploding.

Figure 5-9Digester Gas Membrane Storage Holder (Left, Evoqua) and Open Waste Gas Burner (Varec)

5.3.3.1.2 Digester Gas Conditioning and Cleaning SystemsPrior to being utilized in a cogeneration system, some level of treatment for biogas derived from wastewater sludge is needed to remove moisture and contaminants. The level of treatment depends on the concentrations of the contaminants in the biogas and the end use of the gas. Key contaminants found in digester gas from wastewater residuals include H2S and siloxane.

Moisture removal: digester gas exits the digester in a moisture-saturated state. Water vapor can condense in the conveyance piping and in fuel trains, potentially blocking gas flow. Condensate is acidic and can therefore corrode piping systems and other equipment, as well as impede the performance of other gas utilization technologies. Condensate collection is important, but moisture removal is generally required upstream of CHP and boiler equipment. Moisture removal systems are fairly simple, consisting of a shell-and-tube heat exchanger and cooling the gas to a certain temperature. Condensed water vapor from the gas stream is then piped to drain. Depending on the temperature needed to feed the CHP and boiler equipment, the gas can then be reheated, if necessary, using reheat heat exchangers, dual core heat exchangers, and/or subsequent compression. The cooling fluid can be chilled water or glycol provided by a dedicated chiller, cooling water from a cooling water tower, or even plant effluent.

H2S removal: The H2S in biogas is formed by the reduction of sulfates by anaerobic bacteria and by the mineralization of sulfurous amino acids within the digester. H2S volatilizes into the gas phase and can be corrosive. Combustion of digester gas that contains H2S produces sulfur oxide compounds and water vapor that can condense and produce sulfuric acid, which can damage equipment over long exposure periods. H2S removal technologies for CHP and boiler applications may use adsorption, biological, or chemical systems. Adsorption systems use an adsorptive type media, such as iron oxide, that may or may not be able to be regenerated. After the media becomes spent, it must


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be replaced. Adsorption systems are more appropriate (compared to biological and chemical type scrubbers) for smaller systems like the Madaba WWTP.

Siloxane removal: Siloxanes used in personal hygiene, health care, and industrialproducts are often found in wastewater. Siloxanes volatilize into the biogas. When thisbiogas is combusted, siloxanes are converted into silicon dioxide (SiO2), similar to smallgrains of sand or glass, that can deposit onto combustion or exhaust stages ofequipment. In reciprocating engines used in CHP, the presence of these contaminantscan lead to premature deterioration and excessive maintenance of the equipmentcomponents. Siloxane is commonly removed with activated carbon or similarproprietary media, and combinations of media can be implemented. Some types ofmedia can be regenerated, while others are single-use systems.

Gas compression: The low operating pressures of the digesters are not sufficient forinternal combustion engines or boilers, which generally need 0.1–0.3 bar of inlet gaspressure. Multistage or positive displacement gas blowers can be used to compress thegas into the desired pressure. An inlet particulate filter can be included to remove freemoisture and particulates prior to entering the blower.

The digester gas treatment and conditioning system can be provided as separate equipment or as a vendor-packaged system. For a small facility like the Madaba WWTP, a small packaged system may prove very cost effective and advantageous from an operational perspective to have similar controls and equipment by the same supplier. Moreover, the digester gas treatment system could be combined with the CHP engine system. An example of digester gas cleaning equipment is shown in Figure 5-10.

Figure 5-10Digester Gas Cleaning System

5.3.3.1.3 CHP Engine SystemThe two main technologies used for cogeneration at wastewater treatment facilities are reciprocating engines and microturbines. This alternative focuses on reciprocating engines or internal combustion (IC) engines, the most economical CHP technology with the highest combined electrical and heat recovery efficiencies—over 80 percent. As previously discussed, the heat recovery system can usually provide enough heat (as a hot-water loop) to heat the digesters producing the biogas.

IC engines are less sensitive to biogas contaminants, though moisture, H2S, and siloxane removal is still recommended. One disadvantage of IC engines is their higher emissions compared to microturbines, and areas with strict air quality limits may require additional


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emission controls. Most new IC engines are lean-burn types with lower emission rates than older rich-burn engines. Figure 5-11 is an example of a biogas IC engine.

The CHP system can be provided as separate equipment or a containerized configuration. The first option is very customizable, while the second option provides all equipment in a compact package as a plug-and-play approach. For the Madaba WWTP, a containerized solution may be favorable because the system equipment is consistent and simplified from a single supplier; at the same time, if preferred to be located in a building, providing the equipment separately could be recommended for enhanced access.

In addition to the CHP equipment, one or two backup boiler(s) can be included to heat the digesters, in case the CHP equipment is off-line.

Figure 5-11Digester Gas Engine Generator (Jenbacher)

5.3.3.1.4 Digester Control and Management SystemThe control of the digesters and digester gas utilization systems often consist of one or more PLCs, including some vendor-provided PLCs, especially for the digester gas utilization side. Monitoring flow, pressure, and temperature for both sludge and gas streams are common, and monitoring gas composition is sometimes included as well. Within any buildings, H2S and methane are monitored for safety reasons.

5.3.3.2 CHP Operations and Maintenance Contractor Conventional anaerobic digester with CHP are complex and demanding systems to operate and maintain. To keep the CHP system running efficiently, many similar facilities around the world rely on a third-party vendor (contract) for scheduled maintenance of the CHP system. A similar arrangement is recommended for Madaba WWTP expansion if the CHP alternative is implemented.

5.3.4 Lime StabilizationLime or alkaline stabilization can be used to produce a second-class sludge. Traditional lime stabilization is classified in the U.S. EPA’s Standards for the Use of Disposal of Sewage Sludge as a Class B process (PSRP) (U.S. EPA, 1999b). Many of the advanced alkaline stabilization technologies meet U.S. EPA’s definition of a Class A process (PFRP). The JS for second-class sludge match those for U.S. EPA Class B sludge. Therefore, alkaline stabilization should meet the second-class standards.

The lime stabilization process is very simple. Sludge is stabilized by mixing lime, cement kiln dust, or fly ash into the thickened or dewatered sludge to raise the pH. The mixture is stored for 72 hours (after dewatering) at a pH of 12 and maintained at a temperature of 52 degrees Celsius or higher. Lime can be mixed with the thickened sludge or a pug mill is used to combine lime with sludge cake. The mixture will neutralize or destroy pathogens and


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microorganisms. Both methods are effective but each have advantages and disadvantages. Figure 5-12 presents a schematic of a typical lime stabilization process.

Figure 5-12Sludge Lime Stabilization Schematic (Oerke and Rogowski, 1990).

Lime stabilization process is effective and will generate second-class biosolids. Sludge stabilization is not required to generate third-class biosolids, which are suitable for landfill disposal. Lime stabilization also increases the solids generated. For these reasons, lime stabilization was not considered as a biosolids treatment alternative for this project.

Table 5-10 summarizes the advantages and disadvantages of the sludge lime stabilization process.

Table 5-10 Sludge Lime Stabilization Advantages and Disadvantages


Low capital cost Simple operation Produce higher solids content material Will produce a second-class sludge High pH may allow the reuse potential for the

cake for acid soil

High pH eliminates the reuse potential for thecake if the soil is not acidic

Raw materials are messy Chemical (lime) procurement and costs Biosolids quantity increases as a result of lime

addition


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5.3.5 Aerobic Sludge DigestionAerobic digestion is a bacterial process occurring in the presence of oxygen. A digester tank can receive WAS directly from secondary clarifiers or thickened WAS and provide treatment necessary to achieve second-class biosolids. The U.S. EPA’s Standards for the Use of Disposal of Sewage Sludge as a Class B process (PSRP) (U.S. EPA, 1999b) recommends sludge be aerated/mixed for a period of 40 days at a minimum temperature of 20°C to achieve a minimum VSS reduction of 38 percent. However, aerobic digesters are typically designed to provide “Temperature x SRT” of 500°C-day. For example, at a minimum design temperature of 20°C, sludge can be aerobically stabilized at an SRT of 25 days.

Under aerobic conditions, bacteria rapidly consume organic matter and convert it into carbon dioxide. Once there is a lack of organic matter, bacteria must resort to oxidizing their own cell mass for energy. This stage of the process is known as endogenous respiration. Solids reduction (i.e., VSS destruction) occurs in this phase; sludge mixing and the addition of air are required. Sludge can be mixed by mechanical mixers, diffused air, sludge recirculation, or a combination of these methods. Course bubble air diffusers can be placed on the tank bottom or air can be injected into a sludge recirculation system to maintain a residual dissolved oxygen concentration of 1 to 2 mg/l. Aerobic digestion offers the advantage of an odorless and biological stable product while retaining basic fertilizer values in the sludge. The operating costs are typically much greater for aerobic digestion because of energy costs for aeration. Aerobic digesters are typically mixing-air-limited rather than oxygen-demand-limited at typical solids concentrations, which increases the energy requirement. See Table 5-11 for typical advantages and disadvantages of aerobic digestion.

Table 5-11 Aerobic Digestion Advantages and Disadvantages


Works well for secondary sludge Produces a lower BOD5 supernatant Easy to operate Low capital cost Can produce a second-class sludge

High energy requirement and cost Energy requirement and cost increases when

primary sludge is treated Poor sludge dewaterability Not ideal during cold weather

5.3.6 Sludge Drying BedsDrying beds can only achieve dewatering, which makes it a viable treatment alternative because third-class sludge needs to be generated for landfill disposal. Process description for drying beds is provided in the section describing dewatering alternatives. Sludge must remain on a sand bed to dry at a depth of not more than 25 cm. The sludge must stay in the bed for at least 3 months where the daily air temperature is above 0 degrees C for 2 of the 3 months.

Low operating and capital costs are two primary advantages of drying beds. Land must be available at a reasonable cost for the capital cost to be low. Table 5-12 presents a summary of typical advantages and disadvantages of drying beds. Drying beds are simple systems that require low operator attention and skill level. If a long enough detention time is provided, drying beds can generate second-class sludge.

The main disadvantages of drying beds include odors, visual nuisances, labor-intensive sludge removal, and the process dependence on climate. Drying beds are typically used in warmer climates. The Madaba WWTP has drying beds. However, during colder and wet winter


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months, alternative sludge stabilization and dewatering should be considered for the expansion.

Table 5-12 Sludge Drying Bed Advantages and Disadvantages


Low capital cost (if land is available) Low operating costs Low operator attention and skill level High dry cake solids concentration under ideal

conditions Low chemical and power requirements Low sensitivity to sludge variability Can produce a second-class sludge if enough

drying time is provided

Odors and visual nuisances Labor-intensive sludge removal Large land requirement, highly dependent

upon climate Not effective during cold and wet months Lack of straightforward design approach for

economic analysis

5.3.7 Solids Stream Treatment AlternativesFive solids stream treatment process options were evaluated. The treatment alternatives identified are as follows:

Alternative 1 – Conventional Anaerobic Digestion with Digester Gas Utilization

Alternative 2 – Covered In-Ground Anaerobic Reactor

Alternative 3 – Aerated Sludge Holding Tank

Alternative 4 – Aerobic Sludge Digestion

Alternative 5 – Sludge Drying Beds

Stabilized sludge (solids) dewatering options discussed and considered to be common for all the alternatives.

5.3.7.1 Alternative 1 – Conventional Anaerobic Digestion with Digester Gas Utilization

This solids treatment alternative would use conventional (mesophilic) anaerobic digestion to treat primary sludge and WAS produced by liquid-stream treatment Alternatives A, B, or C, as well as utilize the digester gas produced to generate electricity to offset some of the electricity required to operate the WWTP. This alternative is not practical for use with liquid-stream treatment Alternatives D and E.

Alternative 1 process flow diagram is Drawing No. M-MA-05 and is shown on site plan Drawing No. C-MA-03 with liquid-stream Alternative C.

This alternative would be the more complex, equipment-intensive, and most maintenance-intensive process at the WWTP. Systems and equipment for this alternative include the following:

Primary sludge screening, pumping, and thickening

Septage screening, pumping, and thickening

WAS pumping and thickening


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Anaerobic digestion tanks, reinforced concrete tanks with gas tight covers

Sludge heat exchanger system and recirculation pumps

Sludge pumps

Digester mixing system

Gas conditioning system, including gas compression, moisture removal, hydrogen sulfide removal, and siloxane removal

Gas storage tank

Excess gas flare

CHP engine and heat recovery system

Gas piping and gas safety equipment

Backup boiler(s)

Digested sludge storage tank

Digestion sludge dewatering and disposal

5.3.7.2 Alternative 2 – Covered In-Ground Anaerobic ReactorCIGAR is a simple-to-operate alternative technology to conventional anaerobic digestion (Alternative 1). It is used for the treatment of primary sludge, WAS, septage, and scum produced by liquid-stream treatment Alternatives A, B, or C. Although the rate of volatile solids reduction is slower in CIGARs, the total gas production is a function of volatile solids reduction. The gas generated from CIGARs can also be reused and will be further evaluated if this alternative is selected. This alternative is not practical for use with liquid-stream treatment Alternatives D and E.

Alternative 2 process flow diagram is Drawing No. M-MA-06 and the CIGAR site plan is on Drawing No. C-MA-05 (shown with liquid treatment stream Alternative C, but it can also be used with Alternatives A and B).

Contrary to Alternative 1, CIGAR is among the simplest and lowest maintenance process at the WWTP. Systems and equipment for this alternative include the following:

Five large covered in-ground reactors (lagoons) with high-density polyethylene (HDPE) liner and covers

Inlet for septage, scum, primary sludge, and WAS

Piping or channels between CIGAR cells

Gas collection piping and gas flare

Sludge withdraw piping and pump from the fifth CIGAR cell

Sludge mechanical dewatering and disposal


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Future option CHP system to generate electricity

5.3.7.3 Alternative 3 – Aerated Sludge Holding TankAlternative 3 process flow diagram is Drawing No. M-MA-07 and the aerated sludge holding tank site plan is on Drawing No. C-MA-06.

An aerated sludge holding tank provides a minimal amount of sludge stabilization but is not large enough to produce second-class sludge. It can be combined with another stabilization process (e.g., drying beds) to produce second-class sludge if a long enough drying period is allowed; but, during the wet season, drying beds are not effective and the aerated sludge will not meet the requirements for being sent directly to a landfill. Therefore, this alternative is not considered further for the Madaba WWTP.

5.3.7.4 Alternative 4 – Aerobic Sludge Digestion Aerobic sludge digestion is evaluated for the stabilization of WAS from liquid-stream treatment Alternatives D and E that do not have primary sedimentation.

Aerobic sludge digestion is effective treatment to obtain second-class biosolids, but requires considerable energy to aerate the sludge tanks. For these reasons, aerobic sludge digestion is not considered for Madaba WWTP.

5.3.7.5 Alternative 5 – Drying Bed Drying beds are the most common method of sludge dewatering used in Jordan and the Madaba WWTP has a large quantity of underdrain type drying beds. Drying beds were considered for WAS from Alternates D and E that do not have primary sedimentation. Raw primary sludge dewatering with drying beds was not considered because of the disagreeable nature of primary sludge, including odors and insect attraction. However, dewatering of stabilized sludge with drying beds is considered for all alternatives.

Alternative 5 process flow diagram is Drawing No. M-MA-8 along with Alternative 6 mechanical sludge dewatering. Drying beds are shown on all site plans where a solid-stream treatment alternative is shown because it is included with all options.

Systems and equipment required for this alternative include the following:

Sludge thickening

Sludge pumping and distribution system

Drying beds (underdrain or decant type)

Supernatant collection system

Supernatant pump station to return to the head of the plant

Small front-end loaders (Bobcat) for turning drying sludge and for removal of the sludge

Covered dried sludge storage area until it can be hauled off to landfill

The drying bed infrastructure currently exists at Madaba WWTP and it is anticipated that the WWTP expansion will reuse this infrastructure for sludge dewatering if not stabilization.


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5.3.7.6 Alternative 6 – Lime StabilizationSludge lime stabilization is for the treatment of solids (mainly WAS) from liquid-stream treatment Alternates D and E that do not have primary sedimentation. Although lime stabilization can be used to treat primary sludge, it is not recommended because of the large quantity of sludge produced, the quantity of lime required, and the high cost of operation for chemical and hauling charges.

Sludge lime stabilization is used to produce second-class biosolids with reuse options, but because of the restriction on the reuse of biosolids (discussed in Section 3) and the chemical and hauling costs, this alternative is not considered further for Madaba WWTP.

5.3.7.7 Sludge Thickening and DewateringCondition assessment of the Ramtha and Madaba WWTP and site visits to other WWTPs around Jordan identified that most of the plants are “solids treatment capacity limited,” which means they are unable to process the solids they product. To address the solids capacity limitation, particularly during the cool wet winter months when drying beds are less effective, both drying bed and mechanical dewatering systems are recommended.

Systems and equipment required for the recommended sludge thickening includes the following:

Gravity sludge thickener

Gravity belt sludge thickener

Screw press

Systems and equipment required for the recommended sludge dewatering include the following:

Mechanical Dewatering system (e.g., screw press)

Drying Bed system

Sludge cake and dried sludge storage area

5.3.8 Evaluation of Liquid-Solid Stream Treatment ProcessesSection 8 discusses the evaluation of the liquid-stream and solid-stream wastewater treatment process technologies and recommendations. The remainder of Section 5 discusses options and recommendations for unit process, but are not evaluated in the matrix.

5.4 Preliminary Treatment/HeadworksIn this study, preliminary treatment includes all the typical WWTP headworks infrastructure from where the raw wastewater enters the plant site up to and including the grit removal systems.

5.4.1 Septage ReceivingThe septage unloading station at Madaba WWTP currently receives 500–1,000 m3/d of trucked septage (6 days per week), depending on the season and is projected to decrease over


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time to about 400 m3/d as discussed in Section 2.3.2.1. This plant expansion will replace the existing septage unloading station with a new facility that would cause less splashing septage and odor problems. Current station has splashing and odor problems. The facility is anticipated to be similar to the septage unloading station at the South Amman WWTP, but will be further evaluated during preliminary and detailed design.

The point where the septage enters the treatment process will depend on the treatment alterative selected. If the selected alternative includes anaerobic digestion (Alternative 1), the septage will be thickened and pumped to the anaerobic digester for treatment. If the selected alternative does not include anaerobic digestion, then the septage will be added to the plant liquid stream upstream of the course mechanical screen.

5.4.1.1.1 Septage PretreatmentIf the septage is sent to the plant headworks upstream of the screen, no pretreatment is required (other than 50 mm bar screen) and the septage will flow to the headworks by gravity. However, if the septage is sent to the anaerobic digesters, it will require screening and then be thickened and pumped to the digester.

Septage screening technology is the same system recommended for the screening of primary sludge, which is a horizontal cylindrical coarse material separator, such as the Huber Technology Strainpress® (see Section 5.8.1 Primary Sludge and Septage Screening).

Feedback from MWI/WAJ and MWC advise that the septage typically contains a large volume of grit and recommended that a grit removal system be added to the septage pretreatment system upstream of the sludge screen mentioned above.

5.4.2 Rock TrapA rock trap collections gravel, stones, and other heavy debris from the WWTP influent before they can damage or inundate the headworks. Rock traps are not normally installed at WWTP, but recent experience at the new East Jerash WWTP and other new WWTPs in Jordan indicate that if a rock trap had been installed several operational issues could have been avoided. During winter storms, large volumes of pea-gravel-sized grit, stones, and other heavy materials wash down through the collection system to the WWTP and cause problems at the plant headworks.

At the East Jerash WWTP, a large volume of pea-gravel-sized material passed through the fine screen and settled in the aerated grit chamber. This material was too large to be removed by the grit pump and the tank soon became inundated and the material had to be removed by hand. Between December 2018 and February 2019, more than 50 m3 of this material was removed by hand from the grit chamber.

At the Shallalah WWTP near Irbid in February 2019, rocks (reported to be chucks of concrete) washed into the plant and damaged the mechanical course screen, which then had to be taken out of service and repaired.

5.4.2.1 Rock Trap Concept Since rock traps are not a normal feature, there are few go-by designs and no data on their historic performance. A sketch of the concept devised for the expansion of Madaba WWTP is shown in Figure 5-13. The simple concept is basically a pipe with a section of pipe wall cut out of the bottom over a pit were the rocks and heavy debris would collect. The trap is


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intended to collection rocks greater than 5 mm in size that settle out quickly even at high flow, so the notch cutout only needs to be 500 mm long.

During the dry season the rock trap is not required, therefore a rock trap bypass is implemented so that the rock pit does not fill up with organic solids. The isolation valves are plastic-coated knife gate valves typically used for slurry pipeline to resist the abrasion of the rock and grit coming down the sewer pipe. The valves are presumed to have manual operators but can be equipped with electric motor operators.

Figure 5-13Rock Trap Concept

The rock pit depth and length will depend on site conditions, but should be sized as large as convenient. The rock pit would be cleaned out daily during wet weather using a clamshell bucket mounted on an electric hoist and monorail over the pit and rock draining pad. Clamshell bucket options are shown in Figure 5-14.

The rocks and gravel removed from the rock pit are allowed to drain on the rock-draining pad before a small loader takes the pile away for disposal. A plant water hose station at the rock trap is used to wash down the material on the draining pad to remove the worst of the organics and then drains the pad to return the wash water to the rock trap pit.


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Figure 5-14Rock Trap Clamshell with Electric Hoist and Monorail

5.4.3 Influent Mechanical Screens Screening is used to remove larger nonbiodegradable solids from the waste stream. Effective screening has been shown to aid grit pumping, reduce pump ragging, reduce vertical shaft maintenance, increase performance of digesters, and minimize equipment maintenance. More frequently, fine screening (6 mm openings) is being included in treatment plant headworks design, especially if various advanced processes are employed downstream.

For the Madaba WWTP expansion, it is proposed to locate the screens upstream of the grit removal system.

5.4.3.1 Screen AlternativesThe 2002 Water Environment Research Federation (WERF) Assessment of Technologies for Screening, Floatable Control, and Screening Handling report identified four general categories of coarse screen and eight general categories of fine screen, totaling over 100 versions of “screens.” The general categories are:

Screen Types

Multi-rake screens

Reciprocating rake screens

Continuous element screens

Stair screens

Helical basket screens

Each screen option is discussed in more detail in the following sections.


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5.4.3.1.1 Multi-Rake ScreensMulti-rake screens (Figure 5-15) consist of a static bar screen that accumulates debris along the entire length of the submerged surface. Multiple rakes remove the screenings mat, which constantly travel along the submerged bar, to remove the collected screenings. Screenings are brought to the top of the screen and are discharged to the screenings conveyance system. This type of screen typically contains a robust submerged sprocket upon which the chain rides. When used in fine screening applications, there tends to be more rakes, which allows for higher cleaning frequency and removal of the increased solids load.

When equipped with multiple rakes, this type of screen generally has a low chance of blinding, can handle a high volume of screenings, and has low headloss. An advantage of this screen is that carryover of screened material to the downstream flow is not a concern because screenings are never on the backside of the screen. Required headroom is generally low. However, this unit does have submerged elements that require maintenance. Additionally, this type of screen is limited to one-dimensional bar screening and the screenings’ capture efficiency is not as high as a perforated plate or mesh style screens.

5.4.3.1.2 Reciprocating Rake (Climber) ScreensReciprocating rake or “climber” screens (Figure 5-16) consist of a static bar screen that accumulates debris along the entire submerged length of the screen. This type of screen is available with as little as 6 mm (1/4-inch) spacing. When the headloss exceeds a certain threshold value, a rake moves down from the top of the screen, where it is not in contact with the screen, and then travels to the bottom of the channel where it engages with the screen. The engaged rake travels along the length of the screen to the top where the screenings are discharged into a hopper and the rake is cleaned with a wiper blade. The rake then parks at the top of the screen and repeats the process when headloss through the screen increases to the operator adjustable setpoint.

Because this screen uses guide tracks for the rake assembly shaft rollers, this design eliminates the need for a lower sprocket and drive chain and, thus, the need for permanently submerged moving parts. However, unlike the multi-rake screen, the reciprocating rake screen only has one rake and can quickly become overwhelmed if the screen is blinded with debris.

Figure 5-15 Multi-Rake Screen

Figure 5-16 Reciprocating Screen


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5.4.3.1.3 Continuous Element ScreenThe continuous element screen (Figure 5-17) is a continuous screen that rotates through the influent stream. The screen removes debris from the stream and conveys it out of the channel to the operating floor for discharge. Screenings are discharged from the belt/band by washwater with a counter-rotating brush for effective screenings removal. This screen is available in sectioned metal plates or various plastics (from some suppliers) with circular, rectangular, or square openings.

Wastewater flows through this type of screen and stringy material is captured on its surface. The panels that comprise the surface of the screen carry the debris out of the channel. Once the mat has moved out of the path of flowing water, residual water drains back into the channel.

Captured screenings are discharged to a chute where a counter-rotating drive brush with an integrated spray bar removes solids remaining on the screen. The unit sits at an angle between 60 and 75 degrees to aid in material removal.

The main advantage to the belt/band perforated screens is a high screenings capture efficiency. The perforated plates prevent long thin objects from flowing through the screen without being captured.

Since flow passes through this screen twice, once in the front and once in the back, this screen can have high headloss. Additionally, if any screenings are not removed by the brush and washing system, there is a high chance they will be washed into the process flow because the residual screenings will be on the backside of the screen. The brush is also an added maintenance item.

5.4.3.1.4 Stair (Step) ScreenA step-style screen (Figure 5-18) uses stair-shaped bars to capture screenings. A movable lamella picks up the screenings mat and moves it one step up by moving the mat in an elliptical motion. As material collects on the steps, it forms a mat that acts as a filter to provide increased screening efficiency. When the lamellas operate and move the mat up a step, a clean step is exposed at the bottom of the channel to increase the flow area that has been reduced by the mat. Once the mat has moved out of the path of flowing water, residual water drains back into the channel. The screenings are eventually carried over the top of the screen and into a discharge chute on the backside of the unit.

Figure 5-17 Continuous Element screen

Figure 5-18 Stair (Step) Screen


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Like the multi-rake and climber screen, an advantage of the step screen is that carryover of screened material to the downstream flow is not a concern because screenings are never on the backside of the screen. Additionally, cleaning brushes or spray water streams are not required, and these units typically have a low profile design with minimal equipment above the discharge point. However, disruption of the mat has been shown to discharge some screenings, resulting in a lower capture efficiency than other types of screens where the mat is static.

Because of the small spacing between the steps and movable lamella, material (especially grit) can become jammed between the lamella bars, causing them to flex if the plastic lamella spacers have worn down. Failure of the plastic spacers can lead to premature equipment failure.

5.4.3.1.5 Helical Basket ScreensHelical basket screens (Figure 5-19) consist of an inclined rotating drum and wastewater passes from inside to out, capturing screenings on the inside surface. Rotation of the basket lifts screenings out of the water and allows them to dry slightly before being scraped into an auger with a doctor blade. The auger passes the material through a washing and compaction system. The drum can consist of a perforated plate or bars. This screen generally requires a relatively shallow channel that cannot exceed the diameter of the unit, which is generally under 3 m. Unlike the other screens previously mentioned, once the channel is designed for this style screen, it is difficult or not possible to use a different style screen in the future.

5.4.3.2 Summary and RecommendationAll screens mentioned have the potential to be installed and operated with success at the Madaba WWTP; however, the multi-rake screen is the most suitable for this application. The reciprocating-rake screen is not recommended because of its single-rake arm and the potential for it to become quickly blinded during a wet weather event. The potential for screenings carryover and the maintenance required with the brush system make the continuous element screen undesirable for this application. Because of the thin nature of the lamella plates and the potential for gravel in the waste stream, a step screen is not recommended. CDM Smith has encountered lamella plates that have been bent by debris, creating large gaps for solids to pass through the step screen. Regarding the cylindrical basket screen, as noted above, this style screen requires a shallow style that restricts the use of a different screen configuration in the future.

The multi-rake screen is a robust screen that has been successfully used for decades, with opening sizes from over 25 mm to under 6 mm. The chain and rake system can be operated at different speeds and the multiple rakes allow the screen to clean itself quickly. Unlike the continuous element screen, there is no brush to maintain and no potential for screenings carryover. Although the bottom sprocket is submerged and should be inspected once per year,

Figure 5-19 Helical basket screen


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the design is very robust and replacement of the sprocket should not be expected for at least 10 years.

5.4.4 Grit Removal Grit particles typically include particles of sand, gravel, other mineral matter, and minimally biodegradable material such as coffee grounds, eggshells, fruit rinds, and seeds. Grit removal is needed to prevent unnecessary abrasion and wear of mechanical equipment and deposition inside basins, which can reduce treatment capacity.

There are several technologies available to separate grit for municipal wastewater. Of the technologies available, the ones that would be most applicable to forced vortex systems and aerated grit chambers systems. Both of these technologies have been used for over 30 years at both large and small WWTPs and are described in detail below. Note that in recent years the free vortex, or stacked tray, grit removal system has emerged as technology with the best grit removal efficiency. However, the stacked tray system is primarily used when fine grit, rather than large grit, is an issue, as expected at the Madaba WWTP. In addition, because there is only one manufacturer (Hydro-International) with current installations, it would require a sole-source procurement. Therefore, this technology was not considered further in this evaluation.

5.4.4.1 Forced Vortex Grit Removal SystemThe forced vortex shown in Figure 5-20 is a common method used for grit removal that has been used in North America for several decades. In forced vortex grit chambers, grit settles to the bottom and is removed, while the remaining flow exits the system. The chamber is constructed with a flat or sloped bottom, and a long approach channel to condition the influent flow. A drive shaft runs through the middle of the grit chamber and is fitted with propeller blades. In theory, the blades also create uplift to keep lighter organic material in suspension while allowing the inorganic grit particles to settle into the grit hopper. The grit particles collected in the hopper are then pumped to the grit washing/classifying units for additional processing.

There are several considerations for forced vortex grit removal systems. Forced vortex systems have a large open chamber so that screening debris can easily pass through and typically do not require fine screening upstream. Forced vortex systems require a long straight approach channel at a specific angle and velocity to condition the flow as it enters the chamber, thus reducing performance when flows fall outside of the optimum range. Internal baffle systems have recently been added to maintain acceptable velocity and improve flow range. However, these internal baffles often increase local flow velocities, resulting in additional headloss through the unit. Forced vortex systems are not sized based on theoretical settling principle but, instead, are sized based on incoherent principles. The grit chamber configuration has an effluent channel shelf directly over the influent channel, which creates a potential for short-circuiting of grit as it enters the unit, thus reducing the performance of the grit removal system. Various internal baffle arrangements have recently been added to the chamber to reduce short-circuiting and improve system performance. However, there are fewer installations with the additional baffles. Their curved grit chamber walls and specific approach channel angles tend to result in higher construction cost and tighter construction variance tolerance. The flat floor tends to accumulate grit during low flows, increasing the risk that the grit is flushed out during higher flows. There are several technologies available to separate grit for municipal wastewater. Of the technologies available, the ones that would be


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most applicable to the VCWRF are the forced vortex systems and free vortex (conical tray) systems. Both of these technologies have been used at large WWTPs similar in size to the VCWRF and are described in detail below. Note, aerated grit chambers have also been used at large plants but were not considered in this evaluation owing to the high capital and operating costs and large area required for installation. Table 5-13 lists the advantages and disadvantages of vortex grit removal systems.

Figure 5-20Vortex Grit Removal System

Table 5-13 Vortex Grit Removal System Advantages and Disadvantages


Many installations worldwide Low headloss Less energy-intensive compared to aerated

grit Equipment is maintenance friendly and easy

to operate

Higher construction costs for the curved grit chamber walls

Tight tolerance on construction variance Requires a long straight approach channel Potential for short-circuiting Performance is only optimal within a certain

flow range Unknown technology in Jordan

5.4.4.2 Aerated Grit ChamberAerated grit chambers were the primary technology for grit removal prior to the emergence of the forced vortex systems. Unlike the vortex units, the design of aerated grit chambers has varied widely, with some producing much better results than others. The principle with all aerated grit units is the same—grit is removed by causing the wastewater to flow in a helical, or spiral, flow pattern by introducing air along one side of the chamber, as shown in Figure 5-21. Heavier particles are accelerated and diverge from the streamlines, dropping to the bottom of the tank, while lighter organic particles are suspended and are eventually carried


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downstream. Many aerated grit chambers are equipped with a screw conveyor at the bottom of the take to convey the settled grit to a sump where it can either be pumped or conveyed out. However, with a plant the size of Madaba WWTP, the system could be designed so that grit is pumped directly from sloped sumps along the chamber floor. The main disadvantage of an aerated grit system is the requirement for air blowers, which can be an additional energy load. Table 5-14 list the advantages and disadvantages of aerated grit chambers.

Figure 5-21Aerated Grit Removal System

Table 5-14 Aerated Grit Chamber Advantages and Disadvantages


Proven technology around for several decades Can be constructed with straight walls,

simplifying construction Air can assist in aerating septic wastewater

prior to primary clarifiers Owing to long straight channels, it has a

better setup to incorporate scum removal Jordan has experience with this technology

High energy requirement and cost Blower requires more maintenance than

vortex system Potential for air diffusers to plug or get

tangled with debris.

Figure 5-22 is a conceptual sketch of a grit and grease removal system. A channel bottom scraper (not shown) pushes the grit to one end of the tank where it can be removed by the dry well grit pump. Submersible pumps are not effective at pumping grit, and air lift pumps, although functional, have limitations on the height to which they can lift grit.


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Figure 5-22Aerated Grit and Grease Removal System Sketch

5.4.4.3 Summary and RecommendationVortex grit removal systems have become common at WWTPs around the world because of their compact design and their lower construction and operational costs. However, an experienced WWTP operator in Jordan has not seen the technology in Jordan and is concerned that if the grit pump is not operated constantly the vortex equipment will become incased in grit and restarting the unit will be very difficult. This same operator prefers the aerated grit removal system because the technology is used at many WWTPs around Jordan and the large grit tank provides greater operational flexibility, which is needed in Jordan. For these reasons the aerated grit and grease removal systems is recommended for Madaba WWTP.

5.5 Odor ControlSolids and wastewater contain an array of odorous compounds (or odorants), which can be grouped into the key categories shown in Table 5-15. The table also shows the primary sources of these odorants.

Table 5-15 Wastewater Odorants

Odorant Examples Dominate

Hydrogen sulfide Hydrogen sulfide

Sewer systems Wastewater treatment systems Sludge holding, thickening,

dewatering, and stabilization

Organic sulfur compounds

Dimethyl sulfide Methyl mercaptan Carbon disulfide

Sludge holding, thickening, dewatering, and stabilization

Nitrogen compounds Ammonia Amines

Wastewater anoxic basins


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Odorant Examples Dominate Skatole Indole

Sludge digestion (anaerobic, autothermal thermophilic aerobic digestion [ATAD])

Sludge lime stabilization

Volatile fatty acids Acetic acid Butyric acid Valeric acid

Gravity thickeners ATAD

Aldehydes and ketones Acetaldehyde Methyl ethyl ketone Acetone

Sludge holding, thickening, dewatering, and stabilization

As shown in the table, hydrogen sulfide (H2S) is common to many wastewater and solids processes, but it is not the only compound present in wastewater. Because of its prevalence, especially at headworks, H2S is the focal point for this study.

5.5.1 Odor Control AlternativesA large variety of control technologies is available to treat odorous gases with physical, chemical, and biological treatment approaches. Of the technologies available, those most applicable to the Madaba WWTP are the biotrickling filter and biofilter. Both of these technologies have been used at WWTPs similar in size to the Madaba WWTP and are described in detail below.

Carbon adsorption has been used to treat odors at many WWTPs; however, depending on the H2S concentration, the carbon can be consumed quickly and replacement material may be very costly and difficult to obtain at the Madaba WWTP. Similarly, chemical scrubbers were not evaluated further owing to the chemical and operational costs and complexity.

5.5.2 Biotrickling FilterBiological trickling filters, also known as bioscrubbers, rely on mass transfer and biological oxidation to remove odors. Odorous compounds dissolve and partition into a formed liquid biofilm on the bioscrubber media. The current standard for media is a plastic synthetic material that is inert and acts only to support the growth of microorganisms. This process allows for biological reactions to occur in the biofilm located on the media surface. An acclimation period of up to four weeks is required to develop the biofilm.

Most biotrickling filters are cylindrical towers (see Figure 5-23) filled with one or more layers of inorganic media and equipped with water and nutrient feed systems. Odorous air enters the tower from the base and flows upward, while an intermittent stream of nonpotable water (or for some applications, potable water with nutrients) trickles down across the inorganic media from the top of the tower. The water keeps the media moist and also removes sulfuric acid generated by the oxidation of hydrogen sulfide. Irrigation water can be recirculated. The blowdown from the system has a very low pH (about 2). The inorganic media in most biotrickling

Figure 5-23 Bioscrubber


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filters have a warranted life of 10 years and, in practice, the media life often lasts even longer.

Generally, biotrickling filter manufacturers warrant H2S reductions of 98 to 99 percent and odor reductions of 90 percent, with a maximum outlet concentration typically around 300 to 600 dilutions-to-threshold (D/T) (depending on inlet exhaust gas strength).

Biotrickling filters offer multiple advantages, including a small footprint (as they typically have high loading rates), and the ability to effectively treat a wide range of H2S concentrations. They also generally react well to load variations, although extreme loading swings can adversely impact their operation.

From a performance perspective, biotrickling filters offer H2S removal rates comparable to biofilter systems, but they cannot achieve the same odor removal performance as the biofilters (typically, odor removal warrantees are about 90 percent for biotrickling filters versus 95 percent or greater for biofilter systems).

Advantages and disadvantages of the biotrickling filter are summarized in Table 5-16.

Table 5-16 Biotrickling Filter Advantages and Disadvantages


Small footprint Ease of operation Reacts well to load variations Effective H2S removal for a wide range of

concentrations

Difficulty effectively handling periods of low H2S concentrations

High water use Lower removal of reduced sulfur compounds

5.5.3 BiofilterBiofilters, as shown in Figure 5-24, rely on mass transfer and biological oxidation to remove odors. Odorous compounds dissolve into a biofilm where biological oxidation processes occur. Biofilter media varies by manufacturer, but many units use synthetic media, lava rock, or similar inorganic high-porosity material to support microbial populations. Older designs utilized organic media consisting of composted green material, bark, and woodchips. In contrast to plastic biotrickling filter media, biofilter media often contains nutrients and organic biofilter media also includes a wide variety of indigenous bacteria. Synthetic media and organic media have warranted lives of 10 and 5 years, respectively.

Biofilters can be constructed as in-ground concrete basins or manufactured as compact package units in fiberglass shells. Regardless of their shell construction, all units have an integrated humidification stage to saturate the incoming air stream with surface irrigation and maintain moisture. Overall, the precise configuration of each biofiltration system varies; key differences include flow direction (upflow or downflow) and media type.

Because of the type of media used and high residence times that can be provided, biofilters are particularly suitable for treating complex air streams. Overall biofilter manufacturers warrant H2S reductions of 95 percent or greater and odor reductions of 90 to 95 percent for

Figure 5-24Biofilter Odor Control Unit


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moderate levels of H2S. However, biofilters may not be able to meet this performance if/when high spikes of H2S are encountered. Table 5-17 lists the advantages and disadvantages of biofilters.

Table 5-17 Biofilter Advantages and Disadvantages


Effectively handles wide range of odorcompounds

Reacts well to load variations Higher removal of reduced sulfur

concentrations

More complex operations and maintenancecompared to biotrickling filter

Does not handle high H2S spikes as well as thebiotrickling filter

5.5.4 Summary and RecommendationBiotrickling filters are recommended in Jordan because they remove the most common odor compounds, don’t require chemicals, and are relatively easy to operate and maintain.

5.6 Primary SedimentationPrimary sedimentation (clarification) is the removal of suspended solids by means of physical and chemical methods. Because removed suspended solids include organic matter, the process results in significant reduction of chemical oxygen demand (COD) and BOD5 loads to the downstream biological treatment processes. Primary sedimentation also removes a smaller fraction of the influent nutrient loads that are tied up in the removed suspended solids. Enhanced primary clarification, which requires addition of a flocculant (e.g., ferric chloride), can be implemented to increase solids removal. This is not desirable at the Madaba WWTP because of high chemical cost and negative impacts of too much BOD5 removal on the downstream BNR process. Conventional primary sedimentation can achieve 50-60 percent TSS and 30-40 percent BOD5 removal, which is sufficient for the Madaba WWTP expansion.

In the past, Jordan has preferred wastewater treatment plants constructed without primary clarifiers. However, recent and significant increase in electrical rates has changed this view in interest of reducing the energy requirement of the WWTPs. The primary solids can be treated using anaerobic biosolids treatment processes, which are less energy-intensive (and, in fact, can produce energy) than aerobic liquids treatment processes and aerobic digestion.

5.6.1.1 Primary Clarifier Tank OptionsPrimary sedimentation tanks (or clarifiers, as they are more commonly known) are available in two configurations—rectangular and circular. Each configuration has advantages and disadvantages, as discussed below.

5.6.1.1.1 Rectangular primary clarifierRectangular primary clarifiers have a smaller footprint in comparison to similarly sized circular primary clarifiers. This is because rectangular clarifiers can be constructed with common walls. On the other hand, the main disadvantage of the rectangular primary clarifiers is the maintenance-intensive sludge removal equipment with submerged drive bearings. Table 5-18 presents a summary of rectangular primary clarifier advantages and disadvantages.


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Table 5-18 Rectangular Primary Clarifier Advantages and Disadvantages


More compact footprint Common wall construction is possible

More complex O&M because of the sludgescraper/flight mechanism

5.6.1.1.2 Circular Primary ClarifierThe circular clarifier (primary and secondary) is the more common clarifier configuration in Jordan. Although circular primary clarifiers require larger land, they require much less maintenance than rectangular primary clarifiers. Less maintenance is required because the drive bearings are not submerged. Circular tanks can be constructed with prestressed concrete, which allows for reduced wall thicknesses. Circular tanks require separate flow splitting structures and more yard piping than rectangular tanks. Figure 5-25 is a picture of a circular primary clarifier at the East Jerash WWTP.

In terms of flow pattern, center feed, and peripheral flow, withdrawal is the most commonly used configuration. Table 5-19 presents a summary of circular primary clarifier advantages and disadvantages.

Table 5-19 Circular Primary Clarifier Advantages and Disadvantages


Less O&M needs Lower capital cost

Larger footprint More yard piping

Figure 5-25A Circular Primary Clarifier at the East Jerash WWTP


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5.7 Effluent TreatmentThe Madaba WWTP effluent is provided to the farmers for reuse. Therefore, the treated effluent must be disinfected* to meet the JS described in JS893/2006 for category 3(A) effluent suitable for the irrigation of cooked vegetable crops. Chlorine gas is used for the disinfection of the effluent from the secondary clarifiers to inactivate E. coli and harmful bacteria.

*If the disinfection system is not operational, the plant effluent will not meet the Jordanian Standard for the reuse of the effluent for the irrigation of cooked vegetable crops.

5.7.1 Effluent DisinfectionAn important in concept in disinfection is that of an indicator organism. An indicator organism is a surrogate which indicates the presence of other pathogenic organisms. E. coli very often occupies this role. Effluent disinfection is required to achieve the E. coli limit of the JS Category 3(A) effluent of less than 100 MPN/100ml. The most common disinfection technology used in Jordan is chlorine gas, but other types are discussed in the following sections.

The disinfection system needs to achieve the E. coli limit at the design PHF (2.5 AADF) and have a minimum of two months of chemical storage at AADF.

5.7.1.1 Chlorine Gas Disinfection SystemThe primary disinfection chemical used in the Middle East and Jordan is chlorine gas. Chlorine gas is commercially available in steel containers. It is nonflammable but is a highly toxic respiratory irritant that requires careful handling. When it is added to water, hypochlorous acid and hypochlorite ion are formed in varying concentrations, depending on pH. Both constituents are oxidizing agents that provide disinfection. The addition of chlorine gas also reduces pH and consumes alkalinity. Outside of the desired chemical reactions resulting in disinfection, other reactions can occur. Most concerning are organic reactions that result in the production of disinfection byproducts, which can have negative effects on the environment and human health. Two notable examples are trihalomethanes and chloroform.

Chlorine gas disinfection adds chlorine ions to the effluent and increases the TDS of the effluent at a rate of 1 mg of chlorine and increases the effluent water TDS by 1 mg/l. Normally this is not of concern, but the current Madaba WWTP effluent water already has a TDS concentration and the addition of more TDS is of concern for agricultural reuse. The Madaba WWTP Water and Biosolids Reuse Study (Appendix A) Table 4-2 shows that the effluent TDS averaged 1,020 mg/l, based on the data provided by the Madaba WWTP for 2015–2018.

The anticipated chlorine dose for the Madaba is under 20 mg/l, which could increase effluent TDS as much as 20 mg/l. In comparison to the currently effluent TDS and chloride levels, the anticipated effluent TDS increase is relatively small and should not have a large impact on the reuse potential of the plant effluent.

Although the use of chlorine gas for effluent disinfection has safety concerns, chlorine gas is probably the most cost-effective effluent disinfection method. In addition, the existing plant staff has been using this technology for a long time.

5.7.1.2 Ultraviolet Light Disinfection SystemUltraviolet light (UV) disinfection systems are used at a few facilities around Jordan, including the nearby Shallalah WWTP.


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Upon exposure, UV disinfection causes damage to the genetic material of viruses and bacteria. This method provides disinfection without the use of chemicals, which eliminates the possibility of the production of undesirable disinfection byproducts. In addition, it works well in a wide range of temperatures. An important factor in the effectiveness of UV disinfection is the level of transmittance of the water being disinfected. For high rates of disinfection to occur, UV light must be able to penetrate. If penetration is not easily obtained, an increased cost with higher required intensities will be incurred. From an operational perspective, many plants are hesitant to employ UV disinfection because of the level of maintenance required to maintain lamps. Staff must ensure lamps stay clean to prevent loss of UV penetration. However, unlike chlorine disinfection options, UV disinfection does not add ions and TDS to the water.

The Shallalah WWTP reports they are having problems with ferric chloride residue in the effluent coating and fouling in the UV lamp tubes that decrease the lamp performance. The ferric chloride is used in the anaerobic digestion process to control H2S. The plant stopped using the ferric chloride to keep from fouling the UV lamps, but shortly after the CHP engines started having problems; the issue could be related.

5.7.1.3 Other Chemical Disinfection SystemsThe following chemical disinfection systems were considered but not short-listed because of high chemical costs, operation complexity, and/or that the system is not currently used in Jordan.

5.7.1.3.1 Sodium HypochloriteSodium hypochlorite (NaOCl), also called “hypo,” is the primary chemical used for water disinfection in North America and many other regions in the world. North American municipal plants are increasingly switching to sodium hypochlorite due to the safety concerns associated with chlorine gas. However, in the Middle East region, chlorine gas remains the primary chemical for water and WWTP effluent disinfection. In Jordan, none of the water and wastewater treatment facilities visited by the team had a hypochlorite disinfection system, not even at small water well sites. The use of sodium hypochlorite can be cost prohibitive.

5.7.1.3.2 Peracetic AcidPeracetic acid (PAA) is a relatively new chemical disinfection for WWTP effluent in North America, mainly because follow-up treatment to remove the chemical (de-chlorination) is not required. It is a costly chemical and is not used in Jordan; therefore, it is not recommended.

5.7.1.3.3 FerrateFerrate (FeO4

2–) produced on-site by a patented process using caustic soda, sodium hypochlorite, and ferric chloride has recently been promoted as a disinfectant and coagulant. However, this technology is in its infancy and likely not cost competitive with chlorine gas; therefore, it is not recommended.

See Table 5-20 for typical advantages and disadvantages of chlorine gas, UV and sodium hypochlorite disinfection options.

Table 5-20 Effluent Disinfection Options Advantages and Disadvantages

Chlorine Gas UV Sodium Hypochlorite

Advantages - Low cost of product- Easy O&M

- No toxic chemicals- Compact installation

- A liquid that is safer to storeand handle than chlorine gas


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Chlorine Gas UV Sodium Hypochlorite- Use at most waterfacilities in Jordan

- Material (bleach) is widelyavailable

Disadvantages - The gas is corrosiveand toxic- Extra safetyequipment and training

- High equipment cost- Equipment is proprietary- High powerconsumption- At WWTPs requiresfrequent cleaning

- Degrades quickly at hightemperatures- Corrosive and more O&M thanother options- Large footprint for storagetanks

5.7.2 Effluent FilterEffluent filters are used to polish the effluent at some WWTPs in Jordan. However, for Madaba WWTP, they are not considered necessary because the TSS effluent standard does not require this additional treatment. The project design criteria for effluent TSS limit is 20 mg/l and the Jordanian Standard (Category 3[A]) limit for TSS in the effluent is 50 mg/l; therefore, the effluent filter is not necessary. However, an area on the plant site will be set aside for an effluent filter in the event they are determined desirable in the future.

5.7.3 Plant Water SupplyTreated effluent is pumped from the end of the chlorine contact tank and around the WWTP site in a plant water supply distribution network for use in process and for O&M activities.

5.8 Biosolids Processing OptionsThe following paragraphs describe a series of treatment process options to meet sludge treatment requirements. The original objective is to provide a feasible, economical, and simple method to generate second-class sludge with some reuse potential, but because there is no reuse potential, third-class sludge is the objective. Section 3 contains a description of the different sludge classifications in Jordan and the justification for selecting third-class sludge cake for the design criteria.

Sludge resulting from wastewater treatment operations is usually in a liquid or semisolid liquid form and contains 0.25–12 percent solids by weight, depending on the wastewater operation (Wastewater Engineering, Metcalf & Eddy, Inc., third edition, p. 765). Sludge treatment essentially involves reducing the water and organic content of the sludge and rendering it suitable for final disposal or reuse. Typically, this is a three-step process—thickening, stabilization, and dewatering. Alternative treatment processes for each step are defined below, followed by the recommended processes.

The biological treatment processes were established in previous sections. Primary clarification is recommended to achieve the treatment and energy saving goals. Therefore, there will be primary and waste activated sludge requiring treatment through the biosolids treatment system.

5.8.1 Primary Sludge and Septage ScreeningPrimary sludge and septage contains rocks, plastics, and floatables that accumulate in sludge pipes, thickening tanks, and digester tanks. The material reduces tank capacity and is a


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general maintenance problem and should be removed from the sludge stream as soon as possible.

The same screening technology is recommended for the screening of primary sludge and septage received at the septage unloading station. This is a horizontal cylindrical coarse material separator with 5 mm screen perforation, such as the Huber Technology Strainpress® (Figure 5-26), or equal by Hydro International.

Figure 5-26Coarse Material Separator by Huber Technology

Process AssessmentSome of the primary advantages include a high throughput with minimal footprint requirements. The units need can be located outdoors on an elevated platform and screening collected in a container below the screen. See Table 5-21 for typical advantages and disadvantages.

Table 5-21 Horizontal Cylindrical Coarse Material Separator Advantages and Disadvantages


Space requirements are minimal High screen performance Contained sludge to reduce odors Operational history of removing debris from

primary sludge A simple process No polymers

Moderate operator attention requirements Odors Headloss, repumping necessary


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5.8.2 Biosolids ThickeningSludge thickening is the process of increasing solids content from about 1-percent to approximately 5-percent solids by removing the liquid portion. This represents a five-fold decrease in the sludge volume. The volume reduction is beneficial to the subsequent dewatering process by reducing capacity of tanks and equipment required.

Thickening is achieved by physical means. There are many different methods and process technologies for thickening sludge. The assessment is further complicated where two sludge types are generated at a facility. Technologies discussed below are applicable for these conditions and the most appropriate thickening process is recommended.

5.8.2.1 Gravity Belt ThickenersGBTs have become common practice for thickening activated sludge at wastewater treatment facilities. Gravity belt thickening arose from the application of belt presses for sludge dewatering because of the thickening that occurred in the gravity drainage portion of the presses. GBTs are typically used for thickening secondary sludge or a combined sludge, but not primary sludge alone. An example of a GBT is shown in Figure 5-27.

Figure 5-27Gravity Belt Thickener

Process DescriptionA gravity belt thickener consists of a belt driven over rollers by a variable speed drive unit. Polymer addition is required to condition the sludge. Polymer-conditioned sludge is distributed from a feed/distribution box onto the belt. A series of plow blades along the belt creates ridges and furrows in the sludge to facilitate the drainage of water through the belt. The removal of the thickened sludge from the gravity belt is followed by a wash cycle for the belt.


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Process AssessmentSome of the primary advantages include a high throughput with minimal footprint requirements. The units need to be located in a building and typically have intermediary sludge storage before and after the unit. A GBT can be expected to provide thickened sludge of 4- to 8-percent solids with a typical capture rate of 95 percent. See Table 5-21 for typicaladvantages and disadvantages of gravity belt thickeners.

Table 5-21 Gravity Belt Thickeners Advantages and Disadvantages


Space requirements are minimal Control capability for process performance

are flexible Relatively low capital cost Relatively low power consumption High solids capture High thickened concentrations A very simple process

Excessive Housekeeping Needs Polymer dependent Moderate operator attention requirements Odors Building corrosion potential Not used for primary sludge alone Needs to be located in a building

5.8.2.2 Gravity ThickenersGravity thickeners are very similar to a clarifier where there is a center feed well, a liquid overflow, and sludge scrappers with a thickened sludge hopper. These are usually circular concrete tanks (Figure 5-28) and can be provided with covers to contain odors. Gravity thickeners are used to process primary, secondary, or a combined sludge mixture.

Figure 5-28Gravity Thickener

Process DescriptionSludge is fed to a center well and is allowed to settle and consolidate, while thickened sludge is removed from the sloped bottom of the tank. A liquid overflow, or filtrate, falls over a circumference weir at a rate greater than the minimum required to maintain optimum performance and prevent sludge spoiling.


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Process AssessmentSome of the primary advantages include simplified operation and the ability for continuous operation with minimal operator attention. A gravity thickener can be expected to provide thickened sludge of 4- to 8-percent solids with a typical capture rate of 95 percent. See Table 5-22 for typical advantages and disadvantages of gravity thickeners.

Table 5-22 Gravity Thickeners Advantages and Disadvantages


Effective for all types of sludge Polymer independent Relatively simple and reliable equipment

components Low power requirements Can operate continuously

Significant odor issue if not covered Space requirements High capital cost

5.8.2.3 Rotary Drum ThickenersRotary drum thickeners (RDTs) are not common but are very effective for small treatment facilities. Drum sizing limitation reduces the maximum throughput, which explains the applicability for small treatment systems. An example is shown in Figure 5-29. These thickeners are typically used for secondary sludge, a blended sludge, but not primary sludge alone.

Process DescriptionThe secondary sludge is pumped into a conditioning tank where a polymer is added and mixed with the sludge. The sludge flows by gravity into a slow turning perforated drum, which rolls the solids to the opposite end. The filtrate passes through the perforations and is conveyed back to the liquid process flow stream. RDTs are similar to centrifuges but at lower speed and are not based on centrifugal forces.

Figure 5-29Rotary Drum Thickener


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Process AssessmentSome of the primary advantages include simple operation with low power requirements. The units will need to be located in a building and typically have intermediary sludge storage before and after the unit. An RDT can be expected to provide thickened sludge of 4- to 8-percent solids with a typical capture rate of 95 percent. See Table 5-23 for typical advantages and disadvantages of rotary drum thickeners.

Table 5-23 Rotary Drum Advantages and Disadvantages


Relatively simple and reliable equipmentcomponents and operation

Good odor containment Limited space requirements Low power requirements Relatively low capital cost

Has throughput limitation Needs to be located in a building Polymer dependent

5.8.2.4 Summary and RecommendationFor primary sludge and septage thickening, gravity tank thickeners are recommended because they are effective for these types of sludges, don’t require chemicals, are relatively easy to operate, have low power consumption, and can operate unattended.

For waste activated sludge, gravity belt thickeners are recommended based on operator experience in Jordan and because WAS does not need to be thickened continuously. Therefore, operators can schedule use of the thickeners to meet wasting requirements and based on when the plant is staffed. Also, these types of thickeners have relatively low operating cost and high solids capture.

5.8.3 Biosolids Dewatering TechnologiesSludge dewatering is the process of increasing solids content from about 5 percent to greater than 25 percent. There are many different methods and process technologies for dewatering sludge. The different technologies are discussed below and the most appropriate dewatering process technology is recommended.

5.8.3.1 Screw PressesScrew presses are not common when dewatering sludge, but perform ideally for certain size WWTPs. Use of this technology is unknown in Jordan and there are limited installations in the United States, but it is more common outside of these areas. They have proven successful in providing reliable dewatering of municipal sludge.

Process DescriptionA screw press is a simple, slow-moving, mechanical device. Dewatering is continuous and is accomplished by gravity drainage at the inlet end of the screw and then by reducing the volume as the material being dewatered is conveyed from the inlet to the discharge end of the screw press. Proper screw design is critical because different materials require different screw speeds, screw configurations, and screens to dewater at a high outlet consistency while maintaining an excellent capture rate. Figure 5-30 presents a picture of a screw press.


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Figure 5-30Dewatering Screw Press

Process AssessmentThese presses are known to be very quiet, odor limited, and require low maintenance. A disadvantage is that this technology produces cake of less percent solids than the other alternatives. Screw presses can be expected to provide cake of 25- to 27-percent solids with a typical capture rate of 95 percent. See Table 5-24 for typical advantages and disadvantages of screw presses.

Table 5-24 Screw Presses Advantages and Disadvantages


Enclosed system provides good odor containment

Easy start-up and shutdown, can run automated

Low power consumption Low maintenance requirements Very simple process

Low throughput requires more units and larger footprint

Typically, percent cake solids expected to be lower than centrifuge

Typically, polymer dose expected to be slightly higher

Not effective in dewatering digested sludge

5.8.3.2 CentrifugesDewatering of wastewater sludge by centrifuges is common practice at many facilities around the world. A process common to Jordan, centrifuges were installed at the West and East Jerash WWTPs.

Process DescriptionCentrifuge dewatering uses forces developed by the rotational movement of a bowl to separate the sludge solids from the liquids. Conditioned sludge is pumped through a central pipe into a rotating solid wall bowl. The sludge hugs the inside walls of the bowl as a result of centrifugal force. The heavier particles move to the outside, while the lighter liquid remains pooled in the center of the bowl. A screw conveyor inside the centrifuge moves sludge cake out one end of the unit. The centrate flows out of the other end. Figure 5-31 presents a picture of a typical centrifuge.


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Figure 5-31Dewatering Centrifuge

Process AssessmentThis process is known to be adjustable to variations in sludge, odor limited, average maintenance, but also noisy. Centrifuges can be expected to provide cake of 25- to 32-percent solids with a typical capture rate of 95 percent. See Table 5-25 for typical advantages and disadvantages of centrifuges.

Table 5-25 Centrifuge Advantages and Disadvantages


High degree of dewatering achievable Centrifuges can handle higher than design

loading rates and percent solids recovery canbe maintained with a higher polymer dosage

Odor emissions are minimized becausedewatering process is fully contained

Operators have low exposure to pathogens,aerosols, hydrogen sulfide, and other odors

Compact design minimizes floor spacerequired to install

Can dewater a digested sludge

Polymer consumption is higher than othercomparable technologies evaluated

Experienced operation of equipment requiredto optimize performance of centrifuge

High power consumption and noisy to operate Special structural considerations must be

considered due to vibration and dynamicloading concerns associated with centrifuge

Start-up and shutdown may take up to anhour to gradually bring centrifuge up tooperating speed and slow it down for cleaningprior to shutdown.

High capital cost

5.8.3.3 Belt Filter PressesBelt filter presses are commonly used for sludge dewatering at small and mid-size facilities, which makes them a viable alternative for the Madaba WWTP expansion. The technology is similar to that of a gravity belt thickener, but with a pressure zone that squeezes liquid out of the sludge.

Belt filter presses are designed based on the concept of pressing sludge between two tensioned porous belts passing over and under a series of rollers of varying diameters. For a given belt tension, an increased pressure is exerted on the sludge as roller diameter decreases, thereby separating water from the sludge. Belt filter presses include four basic features—polymer conditioning zone, gravity drainage zone, low-pressure zone, and high-pressure zone. Belt filter presses remove free water from sludge suspensions via several different mechanisms, including gravity separation (similar to the gravity belt thickeners), compression (the sludge is compressed between two fabric belts, squeezing out free water), and shear (as two fabric belts pass around horizontal rollers with the sludge compressed between them). Dewatered sludge drops onto a hopper from which either an enclosed screw


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or a conveyor belt moves the dewatered material to final disposal. Figure 5-32 presents a picture of a typical belt filter press.

Figure 5-32Belt Filter Press

The belt filter presses are known to have several moving parts, can be odorous, and have low-power requirements. Belt filter presses can be expected to provide cake of 15- to 30-percent solids, depending on the sludge characteristics, with a typical solids capture rate of 95 percent. Table 5-26 presents typical advantages and disadvantages of belt filter presses.

Table 5-26 Belt Press Advantages and Disadvantages


Maintenance is relatively simple and belt replacement is simple

High-solids loading capacity and throughput (not as high as centrifuge)

Dewatering operation can start up or resume nearly immediately after a shutdown, thus permitting intermittent operation

Relatively low polymer consumption compared to other dewatering technologies evaluated

Low energy requirement

Odor emissions during operation require adequate ventilation and/or odor control system to maintain air quality in dewatering room

Increased housekeeping requirements Sensitive to varying sludge characteristics Large washwater requirements Requires approximately one hour of manual

wash down and cleanup at the end of each operating shift

Requires special containment curbing and floor drains to collect filtrate and wash water

5.8.3.4 Drying BedsSludge drying beds are standard features at WWTPs in Jordan to take advantage of the long dry season for stabilizing, dewatering, and drying sludge (solids). Sludge drying beds are very effective during the dry season, from April to October, but during the cool wet months of November to March they become less effective and limit the WWTP’s ability to process solids. In addition to warm dry weather, good air circulation over and around the beds greatly improves the sludge drying rate.

The two type of drying beds are underdrain and decant types, with the underdrain being most common at Jordan WWTPs. They operate the same except in how the excess water


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(supernatant) in the sludge is removed, and both can be used to stabilize solids and or dewatering. Table 5-27 presents typical advantages and disadvantages of sludge drying beds. Regardless of the type of drying bed, the two most important factors in drying performance are:

Periodic rotation or turning of the sludge to break the crust and exposing the dampsludge to the air

Air flow (volume) across the drying beds

Table 5-27 Drying Bed Advantages and Disadvantages


Low capital costs Low operation costs, using the sun and wind

to dry the sludge Simple operations Effective when weather is warm and dry

Slow process, typically 2 to 4 weeks to dry Requires large land area and good flow of air

across the site Can have odors and insects Less effective when weather is cool and wet

5.8.3.4.1 Underdrain Drying BedAs the name implies, drying beds that receive wet sludge have an underdrain system consisting of a perforated drainpipe cover with layers of gravel and sand. The excess water drains down through the layers of sand and gravel and is carried way to the head of the plant via the perforated drainpipe, thus leaving the solids on top of the sand to dry in the sun. Once the solids are dry, a small loader (Bobcat) is used to remove the sludge.

Although effective, the sand layer plugs and is carried off when the dried sludge is removed. It has to be replaced regularly and can be an O&M headache.

5.8.3.4.2 Decant Drying BedThe decant drying bed has a hard bottom and walls, so the excess water is removed by decanting. The bed is filled with wet sludge and allowed to settle and then the supernatant on the sludge is drained off the top though a decant gate at the end of each bed. After the supernatant is removed, the solids are left to dry in the sun.

When operated correctly, decant drying beds are just as or more effective than the underdrain type. The advantages are:

Easer to remove the dried sludge

No sand or underdrain materials to replace

Easier to rotate sludge in the bed to provide drying performance

5.8.3.5 Summary and RecommendationTo address seasonal operational constraints and operational cost management, two sludge dewatering technologies are recommended for the Madaba WWTP:

Drying Beds – Sludge drying beds have the lowest operational cost because they takeadvantage of the dry climate, do not require chemicals, and have been used for decadesin Jordan. They perform poorly during the Jordan wet season, which is why a


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mechanical dewatering system is also recommended. Damaged existing drying beds will be rehabilitated, and new drying beds will be of the decant type.

Dewatering Screw Press – Mechanical sludge dewater is recommended for use during the wet season to supplement when the performance of the drying beds is poor. Madaba WWTP currently has one screw press in good condition and it will be reused for the WWTP expansion. Screw press is the recommended mechanical sludge dewatering technology for its ease of operation and long service life.

5.8.4 Sludge DisposalBecause of limitations on the reuse of biosolids from WWTP imposed by JS and the MoA, all biosolids will be sent to landfill following drying. The Al-Ekara landfill in northern Jordan is the only landfill currently taking biosolids and sludge from WWTP; the landfills nearer to Madaba WWTP have refused WWTP sludge because of limited capacity. For this study, it was presumed that the dried biosolids would be hauled over 100 km to the Al-Ekara landfill. The requirement for the disposal of dry sludge at this site is a minimum solids content of 50 percent by dry weight, according to the JS.

5.8.4.1 Biosolids Disposal Alternative Study RecommendedSouth Amman WWTP has the same biosolids disposal challenge as Madaba WWTP. South Amman WWTP has most likely started to store their dried biosolids on-site in areas not intended for the long-term storage of sludge. Because the two WWTPs are in the same area, it is recommended that a study be conducted to find permanent biosolids disposal solutions for both Madaba and South Amman WWTP.


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Section 6Assessment of Effluent and Biosolids Reuse

Water and biosolids reuse (Reuse Study) for the expanded Madaba WWTP was conducted by Ahmad Abu-Awwad, PhD, of Jordan University as a subcontractor to CDM Smith between February and May 2019; the study is included in Appendix A of this report. The requirements of the study are defined in the project agreement Clause 4.10.3, as follows:

i. Identify areas suitable for effluent reuse. Study availability and suitability of the site for effluent reuse. Indicate the size of each area, its present use and land value, and possible other competing future uses. Assess soil conditions for reuse purposes.

j. Study the current agricultural practices in the Project area and determine the crops that could best (agronomically and economically) be grown there with treated effluent.

This section summarizes key recommendations of the Madaba WWTP Water and Biosolids Reuse study and identifies reuse options that could be implemented as part of the plant expansion.

6.1 Effluent Reuse OptionsWater scarcity is an issue for Jordan, and Jordanian policy recognizes the need for the reuse of treated effluent in the irrigation of food and fodder crops, which is the driver for the effluent standards selected for the Madaba WWTP expansion—that effluent may be used for the irrigation of cooked vegetables.

The water and biosolids reuse study prepared by Ahmad Abu-Awwad, PhD (included in Appendix A), identified several possibilities for effluent reuse in the Madaba area. The two options with the most effluent reuse potential (by volume) are discussed below.

Effluent pumping to the Jordan valley for irrigation

Long-term effluent storage near the Madaba WWTP site

The Madaba WWTP is located within the watershed catchment for Wadi Habeeth, which is a tributary to a potable water supply source and Jordan law forbids the discharge of WWTP effluent to wadis leading to potable water sources. This is the reason for the capital-intensive options for the reuse of the treated effluent from Madaba WWTP.

6.1.1 Existing Effluent ReuseCurrently, part of the treated effluent from Madaba WWTP is used for irrigation of fodder and trees by farmers near the WWTP, while the remainder of the effluent is wasted to the wadi. For the sale of effluent to farmers, WAJ received a fee of JD 0.050 JD per m3. Based on 2019 data, the percentages for effluent reuse is approximately:

Revenue effluent water: 46.2 percent, sold to farmers that have a contract with WAJ

Section 6 Assessment of Effluent and Biosolids Reuse

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Nonrevenue effluent water: 32.3 percent, no contract between farmers and WAJ, butfarmers receive water anyway

Wastage: 21.5 percent, discharge to wadi

6.1.2 South Amman WWTP Treated Effluent ReuseSouth Amman WWTP is a large and relativity new facility located 15 km southeast of the Madaba WWTP. The MWI/WAJ had requested USAID Jordan Infrastructure in October 2019 to conduct a study for the reuse of the treated effluent from both the Madaba and South Amman WWTPs. In January 2020, USAID decided not to include this study under Task 9 of USAID Jordan Water Infrastructure and this option is not included this report. However, there may be significant cost and reuse potential advantages in a reuse strategy that combines the effluent from the Madaba and South Amman WWTPs, and the concept should be investigated further by MWI/WAJ.

6.2 Biosolids Reuse OptionsThe WWTP biosolids contain nutrients (such as nitrogen, phosphorus, and potassium) and organic matter that can reduce the use of conventional fertilizers and improve soil quality. The use of treated sludge (biosolids) from the Madaba WWTP for agricultural purposes is the most effective and environmentally friendly technique; specifically, for biosolids that are applied to lands used to grow fodder crops.

However, despite the technical specifications in JS1145/2006 and JS1145/2016, the technical regulations issued by the MoA (Z3/2016) and the MoE (2009) prohibit the production and use of organic fertilizers “originated from WWTPs.” Thus, the only consideration for Class 1 and Class 2 biosolids end use is designated for rangelands (JS1145/2016), which is not addressed or mentioned in the technical regulations issued by the MoA or the MoE. Therefore, no biosolids reuse options are discussed in this report.

6.3 Effluent Reuse Options and InfrastructureThe water and biosolids reuse study report (Appendix A) identified two viable effluent reuse options that would avoid effluent waste by discharge to the wadi:

Option I – Status quo

Option II – Pump the effluent to the Jordan Valley for irrigation of crops

Option III – Effluent storage to maximize effluent reuse for local irrigation

6.3.1 Effluent Reuse Option I – Status QuoThe status quo option is included to represent the no-build case for the financial and economic analysis in Section 8 for comparing the other two effluent reuse options. Although this option represents the current reality for the Madaba WWTP, it is not recommended because it allows for the continued wasting of effluent to a tributary leading to a potable water source.

6.3.1.1 Option I Effluent Reuse Assumptions Existing effluent reuse contracts for the Madaba WWTP effluent show they follow effluent reuse quantities that represent the status quo for Effluent Reuse Option 1:


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Revenue effluent water sold to nearby farms: 46.2 percent, farmers that have contracts with WAJ

Nonrevenue effluent water: 16.2 percent, farmers without contracts who receive effluent but do not have to pay

Wastage: 37.6 percent, effluent discharged to the wadi because it was produced when there was no demand for irrigation

6.3.2 Effluent Reuse Option II – Effluent Pumping to the Jordan Valley for Irrigation

This option would pump excess treated effluent from the Madada WWTP on-site effluent storage pond to the Kafrien Dam reservoir where it can be used in the Jordan Valley for irrigation of crops. Excess treated effluent is effluent not needed for irrigation of crops near the Madaba WWTP at time of production. The main components of this option are:

On-site effluent storage pond with 2-day effluent storage that is already included as part of the WWTP expansion.

Effluent pump station on the Madaba WWTP site to pump effluent through the force main to the high point near Nour. This pipeline is approximately 18.2 km long and presumed to be ductile iron pipe installed by conventional open trench construction in public road right-of-way.

Force main from the Madaba WWTP to the pipeline alignment high point about 4 km south of Naour, where a small ground level tank is required to transition from piped pressure flow to gravity flow. This small concrete structure would be on a site of approximately 2,000 m2 that would require land acquisition.

Gravity pipeline from the ground tank down into the Jordan Valley to where it would discharge to a tributary leading to the Kafrien Dam reservoir. This section of pipeline is approximately 11 km long, following penstock construction methods with steel pipe to resist the high pressure and thrust forces on the pipeline.

Flow energy dissipation structure to flow the water coming out of the penstock before discharging to the wadi.

This option has design and construction challenges, including:

Instilling along high-traffic roadways and congested areas

Cross of a main highway requiring trenchless construction

High pressure and thrust forcing in the penstock (gravity section) pipeline

Steep slopes and poor soil conditions going down into the Jordan Valley where the penstock would be installed

A possible alignment for the effluent reuse pipeline to the Jordan Valley is presented on Drawing No. C-MA-7 along with the pipeline profile.


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6.3.2.1 Option II Effluent Reuse Assumptions This option assumes that farmers near the WWTP will have first rights to the treated effluent and only the excess effluent is pumped to the Jordan Valley. In addition, all the effluent generates revenue with the sale under contract to the nearby farms or conveyed to the Jordan Valley, and there is no wastage of treated effluent. The presumed percentages for effluent reuse are as follows:

Revenue effluent water sold to nearby farms: 62.4 percent, includes farmers withcurrent water purchase contracts with WAJ (46.2 percent) plus half of the farmerscurrently receiving water without contracts (16.2 percent) will elect to purchaseeffluent from WAJ.

Revenue effluent water sold to the Jordan valley: 37.7 percent, includes all the effluentcurrently wasted to wadi plus half of the farmers currently receiving water withoutcontracts (16.2 percent) will not sign contract with WAJ and not receive water.

Nonrevenue effluent water: 0 percent, discontinued

Wastage: 0 percent, discontinued

6.3.2.2 Effluent Reuse Option II – Opinion of Possible Construction CostConceptual-level construction costs are presented below. Because they are conceptually* based on minimal design, they have a low level of accuracy and should only be used for comparing options.

This option contains risk and construction complexities that may not be fully realized in the cost presented above.

Land acquisition for the high service tank is required and estimated cost is

The estimated electrical power consumption for the pumping is 0.665 kWh per m3 of. effluent pumped

This is only a conceptual study. The next design step would be to prepare a feasibility study*

report to identify alternative pipeline alignments and technologies, including trenchless. construction and tunneling

Effluent Reuse Option III – Long-Term Effluent Storage for Local 6.3.3

IrrigationThis option would hold the treated effluent in large long-term storage ponds (up to one year). The issue is that the need (demand) for irrigation water by nearby farms does not match the supply of treated effluent from the WWTP, resulting in the wasting of effluent during low-


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demand periods and a shortage during high-demand periods. These large ponds would help to balance the demand for irrigation water with the supply of effluent.

The Madaba WWTP effluent and biosolids reuse study report (prepared by this project and included in Appendix A) identified that an effluent storage volume of 1.2 million cubic meters (MCM) would be needed to minimize the wasting of treated effluent and maximize the reuse potential for irrigation at farms near the Madaba WWTP. The main components of this option are:

On-site effluent storage pond with 2-day effluent storage that is already included as part of the WWTP expansion

Pump station at the on-site effluent storage pond to convey the effluent to the long-term storage ponds.

Two large earth embankment ponds with a combined usable volume of 1.2 MCM and HDPE pond liner

Floating pond cover to control algae growth and evaporation

Pump station at the long-term effluent storage pond site to convey the water from the ponds to the local farmers, when needed

Site boundary fence and security guard building

Land acquisition

The effluent would be disinfected at Madaba WWTP prior to pumping to the long-term storage ponds. Once the effluent is in storage, the water quality will degrade.

Figure 6-1 shows the relative size of the long-term effluent storage ponds comparted to the Madaba WWTP site; however, this is not the site selected for the ponds. If this option were to be selected, a site for the ponds would have to be identified.

This is only a conceptual study for the comparing of effluent reuse options. The next step would be to prepare a feasible study that would include the identification of sites suitable for placing the large long-term effluent storage ponds.


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Figure 6-1Long-Term Effluent Storage Pond Compared to the WWTP Site

6.3.3.1 Option III – Effluent Reuse Assumptions This option assumes that all the farmers near the WWTP will utilize and pay for 100 percent of the effluent generated by the WWTP through the year 2045 because the large storage volumes allow for the effluent to be available when the farmers need it. No water is pumped to the Jordan Valley or pumped more than a few kilometers from the WWTP. The presumed percentages for effluent reuse are as follows:

Revenue effluent water sold to nearby farms: 100 percent, all uses will have contractswith WAJ and will pay for the water they use

Nonrevenue effluent water: 0 percent, discontinued

Wastage: 0 percent, discontinued

6.3.3.2 Effluent Reuse Option III – Opinion of Possible Construction CostConceptual level construction costs are presented below. Because they are conceptually based on minimal design, they have a low level of accuracy and should only be used for comparing options.

Basinconstruction and indirect costs: USD xx million


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Contingency(30percent) for uncertainty in conceptual design: USD xx million

Totalconstruction costs: USD xx million

Land acquisition for the long-term storage pond is required and estimated cost is USD xxx. million for 366,000 m2 at USD xx.xx per m2

Operation of the effluent pump station is presumed to have similar cost to the existing effluent pump at Madaba WWTP. The estimated electrical power consumption for the pumping is 0.151 kWh per m3 of effluent pumped.

6.3.4 Fodder Irrigation in South Amman AreaThere is a current scheme for irrigation of fodder crops in the South Amman area between MWI and farmers (21 signed agreements)—Cooperative and Charities Societies—to cultivate 7,132 du (713.2 ha) with 5.7 MCM/y with effluent from the South Amman WWTP. However, only 984 du were planted, as reported by the MWI/JVA in October 2019. In April 2018, the area under cultivation was 1,737 du. This reduction in cultivated area is believed to be attributed to the farmers’ limited experience in irrigated agriculture as opposed to their experience in growing rainfed crops.

Madaba WWTP is approximately 15 km to the west of this area and at a similar ground elevation. However, utilizing treated effluent from Madaba WWTP to irrigate an agricultural area in South Amman is not recommended for the following reasons:

At present, there is plenty of excess effluent emitted from South Amman WWTP toirrigate the area currently under cultivation and supply the needs of the 7,132 duProject area (around 6 MCM)

The currently planted area is only 984 du, as of October 2019

The distance from Madaba WWTP to the agricultural targeted area is almost 3 times thedistance from South Amman WWTP and would require the construction of additionalinfrastructure

6.3.5 Madaba and South Amman WWTPs Combined Effluent ReuseIn 2019, MWI/WAJ requested support from USAID Jordan Water Infrastructure in analyzing the treated effluent reuse options for the Madaba and South Amman WWTPs. USAID considered conducting this study under USAID Jordan Water Infrastructure Task 9; then, in January 2020, USAID decided not to conduct this study through USAID Jordan Water Infrastructure. However, this task is included in the new USAID Request for Qualification (RFQ) called the Jordan Water Engineering Services.

6.3.6 Options Considered, But Not EvaluatedOptions considered, but not evaluated (because they were considered impractical or involved extensive study beyond the scope of USAID Jordan Water Infrastructure) included:

Pumping effluent to the Dead Sea – A shorter conveyance pipeline and less pumpingthan Option II, but there is no reuse option, so the effluent would be wasted and thereare concerns that the additional flow would cause excessive erosion in the wadi leadingto the Dead Sea.


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Convey effluent to east into the desert – The effluent could be used for irrigation or allowed to infiltrate into the desert sands. Would be more practical to combine with South Amman WWTP effluent reuse option and consider beyond the scope of Task 4 Expansion of Madaba WWTP.

Convey effluent to Azraq Wetlands Reserve for wetland conservation – Would require a pipeline over 100 km long (mostly downhill); not evaluated or considered beyond the scope of Task 4 Expansion of Madaba WWTP.

6.3.7 Recommended Effluent ReuseNone of the options evaluated provide a clear cost and effluent reuse advantage. The practical Options (II and III) involve significant construction costs, while the status quo Option (I) would result in the continued valuation of Jordanian regulation of the discharge of treated effluent from municipal WWTPs.

Effluent reuse Option III has the lowest construction and operating cost but requires the acquisition of a large portion of land within a responsible distance of the WWTP.

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Section 7Financial and Economic Analysis

This section was not updated in the final report.

7.1 Financial Analysis OverviewThe financial analysis develops a cash flow projection for each WWTP alternative from the anticipated start of operation in 2024 through 2045. Each WWTP alternative presumes the base case effluent reuse option of basic storage only, as discussed in Section 6.3.1. The analysis includes annual debt service on capital costs not funded through grants, annual operating and maintenance costs, annual renewal and replacement costs, anticipated annual revenues, and a residual value at the end of 2045. The alternatives are compared on a net present value (NPV) basis using a discount rate of 5 percent. Cash flows are discounted back to 2019 to be consistent with the Ramtha analysis.

General escalation is presumed to be 3 percent per year, based on consumer price index information for Jordan over 20 and 25 year historical periods, as reported in January 30, 2019 Federal Reserve Economic Data using World Bank data.1

Note – In the final version of this feasibility study report this section was not updated to include the changes in the WWTP construction cost per the December 2020 OPCC update.

7.1.1 Projected FlowsThe 5-year flows shown in Table 2-2 of the main report were used for the financial analysis. Flows for interim years were estimated using linear interpolation. Table 7-1 summarizes the annual projected wastewater flow into the plant. As the wastewater stream is processed, the flow through various processes differs from the influent flows. The estimated process flows are discussed in Appendix H of this tech memo. The increased flow will occur, in part, because of new connections to the system, which are discussed later in this memo.

Table 7-1 Projected Annual Influent Flow to Madaba WWTP, MCM

Year Annual Flow (MCM) Year Annual Flow

(MCM) Year Annual Flow (MCM)

2024 3.57 2031 4.48 2039 5.362025 3.65 2032 4.59 2040 5.482026 3.79 2033 4.70 2041 5.552027 3.93 2034 4.81 2042 5.622028 4.07 2035 4.93 2043 5.692029 4.22 2036 5.03 2044 5.772030 4.38 2037 5.14 2045 5.84

2038 5.25

1Federal Reserve Bank of St. Louis and World Bank, Datalist Consumer Price Index for Jordan, retrieved from FRED, Federal Reserve Bank of St. Louis, https://fred.stlouisfed.org/series/DDOE01JOA086NWDB, accessed June 11, 2019.

Financial Section has been deleted

https://fred.stlouisfed.org/series/DDOE01JOA086NWDB,

Section 7 Financial and Economic Analysis

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Section 8Evaluation of Treatment Alternatives

8.1 Short-Listing of Treatment AlternativesThe recommended short-listed alternatives from Section 5.2.6 for the expansion of the Madaba WWTP are accessed according to the criteria below to identity the most appropriate alternative for this WWTP.

8.1.1 Short-Listed Combined Liquid/Solid Stream Alternatives Initial screening of the liquid-stream process alternatives and the solid-stream process alternatives resulted in the six combined liquid/solid-stream alternatives listed in Table 8-1.

Table 8-1 Short-Listed Combined Wastewater Treatment Alternative

Alternative ID Alternative Description

A.1 A. Modify existing aeration tanks to BNR (five-stage Bardenpho with plug flow) with primaryand secondary clarifiers1. Conventional anaerobic digestion with CHP electricity generation from biogas

B.1 B. BNR OD (five-stage Bardenpho) with new primary and secondary clarifiers1. Conventional anaerobic digestion with electricity generation from biogas

B.1A B. BNR OD (five-stage Bardenpho) with new primary and secondary clarifiers1A. Conventional anaerobic digestion with future option for CHP to electricity generationfrom biogas (newly added alternative)

C.1 C. BNR (five-stage Bardenpho with plug flow) with primary and secondary clarifiers1. Conventional anaerobic digestion with CHP electricity generation from biogas

C.1A C. BNR (five-stage Bardenpho with plug flow) with primary and secondary clarifiers1A. Conventional anaerobic digestion with future option for CHP to electricity generationfrom biogas

C.2 C. BNR (five-stage Bardenpho with plug flow) with primary and secondary clarifiers2. CIGAR with future option for electricity generation from biogas

C.3 C. BNR (five-stage Bardenpho with plug flow) with primary and secondary clarifiers3. Aerated sludge holding tank

D Not usedE E. BNR (five-stage Bardenpho with plug flow) with new secondary clarifiers (no primary

clarifiers)Note: All alternatives include sludge thickening and two methods of sludge dewatering. The two dewatering technologies are: drying beds (Alternative 5) and mechanical dewatering (Alternative 6). Alternative B.1.A was added following the evaluation and was not evaluated in Section 7.

8.2 Assessment of Process Treatment AlternativesThis section describes the metrics used to evaluate the combined liquid/solids stream short-listed alternatives and the corroding scoring and matrix weighting system. The evaluation matrix scoring and results tables are included in Appendix E.

Section 8 Evaluation of Treatment Alternatives

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8.2.1 Assessment CriteriaThe following factors provide a qualitative method for ranking the treatment technologies and a means for making a recommendation. The assessment criteria have five main categories with subcategories as follows:

Operational complexity

o Reliability

o Flexibility

o Maintenance complexity

o Process complexity

o Chemical requirement

Material requirements

o Proprietary products required for construction phase

o Proprietary products/consumables required for operation phase

o Local fabrication opportunities

o Reuse of existing structures

Constructability

Meets Effluent Objectives

O&M Costs

o Energy

o Chemicals

o Labor

Capital Costs

o Land acquisition required

o Electrical service upgrade

o Construction contract

o Construction management

o Two years of O&M by contractor

Life-cycle costs from estimated plant start-up in 2023 through the design horizon 2045.

Description of each assessment criteria category and subcategory follows each subsection.


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8.2.1.1 Operational ComplexityOverall operational complexity of the alternative is defined by the following four subcategories. Each subcategory is scored from 1 to 5 and contributes to the overall alternative scoring. A score of 1 indicates the alternative has high-operational complexity while a score of 5 indicates low-operational complexity.

8.2.1.1.1 ReliabilityThis is the reliability of the alternative, the biological process, and the overall system ability to operate with minimal chance of failure through the design year. Considerations include the anticipated years of operation, size of facilities, history of operation and maintenance, potential problems, and process performance, as measured by expected effluent water quality. Alternatives are ranked by these criteria:

Ranking of 1: Process components struggle to achieve required treatment undersimilar site conditions and at several different installations

Ranking of 3: Process components usually achieve required treatment under similarsite conditions and at several different installations

Ranking of 5: Process components always achieve required treatment under similarsite conditions and at several different installations

8.2.1.1.2 FlexibilityFlexibility of the process and system to changing conditions and ability to make modifications to or expand the process in the future. Flexibility for changing conditions include increased strength of the plant influent caused by water scarcity and changing weather conditions owing to climate change. Flexibility for future modification include expansion of the plant in parallel and ability to make changes to existing systems in response to changing conditions or needs. Alternatives are ranked by these criteria:

Ranking of 1: Very little flexibility ability is expected

Ranking of 3: Flexibility is likely to be average

Ranking of 5: A high level of flexibility is anticipated

8.2.1.1.3 Maintenance complexitySome processes require greater maintenance and attention than others. For example, required maintenance for brush aerators is more easily observed than that for a diffused aeration system. Where resources are limited, high maintenance can represent future challenges. Alternatives are ranked by these criteria:

Ranking of 1: Intensive maintenance requirements

Ranking of 3: Maintenance is likely to be average

Ranking of 5: A low level of maintenance is anticipated

8.2.1.1.4 Process complexityThe difficulty of operating a process is considered. Some processes are complex and require a lot of attention for proper operation. Some processes require special skills and extensive training for the operators. Alternatives are ranked by these criteria:


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Ranking of 1: Processes are difficult to operate or require special skills

Ranking of 3: Processes require average attention and some additional staff andtraining

Ranking of 5: Less complex processes

8.2.1.1.5 Chemical requirementChemical inputs necessary for the continued operation of the treatment plant is an important consideration for the facility owner and operator for the cost and operational complexity. Chemicals are generally imported into Jordan and are relatively expensive and often not available to the plant operators and, therefore, are an important consideration for the continued operation of the facility. Alternatives are ranked by these criteria:

Ranking of 1: High level of chemical required and/or chemical critical to theperformance of the process to meet discharge standards

Ranking of 3: Chemical addition preferred but chemical not critical to the performanceof the process

Ranking of 5: No chemical addition required

8.2.1.2 Material RequirementsAssessment of special or proprietary materials is required in the construction of the facility and for the continued operations to meet the effluent treatment objectives during long-term operations. Because of Jordan’s limited industrial base and resource limitations, many of the required materials for construction and operation as well as consumables need to be imported at relativity high costs. These criteria give preferences to equipment and consumables that can be sourced locally and discourages systems reliant on highly specialized materials.

8.2.1.2.1 Proprietary products required for construction phaseJordan does not manufacture much, so most materials and almost all equipment are imported and have a higher cost than other places. Process and equipment that are highly dependent upon specialized imported materials or are proprietary with limited source for replacement parts should be avoided in the construction phase to keep the cost of consumables and replacement parts to a minimum during the operation phase. Alternatives are ranked by these criteria:

Ranking of 1: Equipment and processes with proprietary and specialized equipment

Ranking of 3: Equipment and process with some proprietary and specializedequipment

Ranking of 5: Equipment and process with no proprietary and specialized equipment

8.2.1.2.2 Proprietary products/consumables required for operation phaseConsumables (e.g., chemicals, lubricants) and spare parts that are proprietary products or have limited availability in the Middle East regions need to be minimized to obtain long-term effective operation of the processes and facility. Avoid consumables and spare parts required


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for sustained operations of the facility (and meet treatment objectives) that are only available in North America and Europe.

Ranking of 1: Consumables and spare parts that must be procured from outside theregion, and special proprietary projects such as oil or process replacement parts

Ranking of 3: Consumables and spare parts including any proprietary products thatare available in Jordan or within the Middle East, and the proprietary products are nothigh cost

Ranking of 5: Consumables and spare parts are all available in Jordan or within theMiddle East region, and no proprietary products

8.2.1.2.3 Local fabrication opportunitiesJordan does have some manufacturing and fabrication capability, which should be taken advantage of to reduce construction and operation costs while maintaining the integrity of the treatment process and plant. For example, process and storage tanks that can be fabricated in Jordan are preferred to imported tanks to keep costs down and simplify reports. Also, equipment that can be obtained from the local market would facilitate future replacement of spare parts. Alternatives are ranked by these criteria:

Ranking of 1: Ability to local fabrication or sourcing of no items

Ranking of 3: Ability to local fabrication or sourcing of some items

Ranking of 5: Ability to local fabrication or sourcing of many items

8.2.1.2.4 Reuse of existing structuresAlternatives that include reuse of existing plant infrastructure in the WWTP expansion are ranked by these criteria:

Ranking of 1: No existing process structures incorporated or repurposed in the WWTPexpansion

Ranking of 3: Some existing process structures incorporated or repurposed in theWWTP expansion

Ranking of 5: Large amount of existing process structures incorporated or repurposedin the WWTP expansion

8.2.1.3 ConstructabilityThere are clear variations in the magnitude of construction required between the different alternatives being considered. For example, construction on an existing site, rather than a new site, presents greater challenges. Alternatives that require a flow transfer or have many processes to maintain in operation during construction would be a challenge to implement. The constructability includes the degree of construction difficulty, duration, scheduling, and compatibility with existing facilities, structures, piping, and similar issues. Constructing the unit processes is also influenced by the degree to which staging is required. Alternatives are ranked by these criteria:

Ranking of 1: Excessively difficult construction


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Ranking of 3: Construction difficulty is likely to be average

Ranking of 5: A low level of construction difficulty

8.2.1.4 Effluent Objectives MetThe alternatives were selected with the intention that they could achieve the effluent treatment objectives, but some processes are more reliable than others at consistently meeting the objectives. Alternatives are ranked pass or fail, based on their ability to meet the treatment objectives 90 percent of the time.

Ranking of Pass: Process is reliable in meeting the treatment objectives at least 90percent of the time

Ranking of Fail: Process is not reliable in meeting the treatment objectives at least 90percent of the time

8.2.1.5 O&M CostsAverage annual O&M costs include general maintenance, labor, supplies, and mostly power requirements. Mechanical equipment with high horsepower demands results in high O&M costs. The assessment for these criteria is based on the estimated annual cost without inclusion of significant repair and replacement costs.

Costs are in U.S. Dollars and are averaged over the period 2024–2045.

8.2.1.5.1 EnergyCost of energy (electricity) required to operate the process motors that are necessary for archiving treatment objectives on an annual basis, typically based on the required horsepower (kilowatts) required at the design horizon average day flow. Energy required by backup systems, such as a standby generator, is not considered in this evaluation.

Since mid-2018, the electrical rate paid by electrical water treatment facilities in Jordan is US$0.16 per kWh plus a fuel diffractal surge charge that is seasonally variable and adds between US$0.01 to US$0.04 per kWh to the monthly electrical usage. For this study, an average rate of US$0.186 per kWh for 2018 was used.

Where energy can be recovered by a process and utilized at the plant, the energy recover is estimated and converted to the equal dollar amount and appears as a negative value in the matrix table.

8.2.1.5.2 ChemicalsChemicals required by the treatment process either for daily operations or for periodic cleaning are estimated on the cost in the local market present day costs in quantities required to achieve the treatment objectives in 2045.

8.2.1.5.3 LaborEstimated labor (plant manager, operators, and tech staff) required to efficiently operate the facility and meet the treatment objectives, including reducing staff to cover holidays and time off.


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8.2.1.5.4 OtherOther plant operation and maintenance costs, such as replacement of spare parts, lubricants, and subcontracting for items like equipment repair and dried sludge hauling to landfill.

8.2.1.6 Capital Costs:Conceptual level opinion of possible construction cost in present day (2019) U.S. Dollars for all the following items.

8.2.1.6.1 Land acquisition requiredAlternatives that require land acquisition by the Government of Jordan for the plant expansion. If sufficient land for the plant expansion is already owned by WAJ, then this amount is zero.

8.2.1.6.2 Electrical Service UpgradeUpgrade of the electrical service connection at the plant site necessary to meet the requirements of the plant expansion.

8.2.1.6.3 Construction ContractThe present-day costs to contract for construction of the facility in USD, including project general conditions, contractor’s overhead and profit, and contingencies. The contingency includes unknowns in design as well as construction and is 30 percent for the conceptual design stage.

8.2.1.6.4 Construction ManagementThe present-day costs for construction management services to oversee the construction contractor. This is presumed to be 5 percent of the construction contractor cost.

8.2.1.6.5 Two years of O&M by ContractorThe present-day costs for two years of O&M services provided by the construction contractor following plant start-up. In the first year of plant operation, the flows are anticipated to be less than in 2045; an average flow of 10,000 m3/d was used.

8.2.1.7 Life-Cycle Cost Through Design Horizon 2045Life-cycle cost analysis incorporated initial capital costs, ongoing plant operation and maintenance costs, and other ongoing costs to determine the overall cost of the facility through 2045. Explanation on the components that make up the life-cycle operation and maintenance costs are provided in Section 7. The life-cycle costs used for this analysis are the construction costs and annual O&M costs and do not include financial charges and interest required to finance the project. These charges are included in the Section 7 financial analysis.

8.2.2 Category and Subcategory WeightsCombinations of alternatives were identified for liquid stream (Alternatives A to E) and solid stream (Alternatives 1 to 5), and a value was applied to each to weight the categories and subcategories by importance. A scope for each liquid/solid-stream combined alternative was normalized and calculated to have a numeric value for comparison; the high score was the more favorable liquid/solid-stream alternative. Table 8-2 lists the weight values assigned to each category and subcategory.


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8.2.2.1 Category WeightA weight was applied to each category to define a specific category’s importance within the seven categories with all seven categories totaling 100 percent.

8.2.2.2 Subcategory WeightEach subcategory was assigned a weight (points) to define a specific subcategory’s importance within the category. The total points assigned to the subcategories within a given category totals 100.

8.2.2.3 Subcategory PointsThe category weight and subcategory weight were multiplied to obtain the subcategory point, which was then multiplied by the liquid/solid-stream alternative process performance score.

Table 8-2 Category and Subcategory Weight Values

Criteria Process Performance Score

Category Weight

Subcategory Weights

8.2.1.1 Operational Complexity: 35 percent Reliability 1 to 5 - - 10 Flexibility 1 to 5 - - 5 Maintenance Complexity 1 to 5 - - 30 Process Complexity 1 to 5 - - 25 Chemical Requirement 1 to 5 - - 30

- - - - Total 1008.2.1.2 Material Requirements: 10 percent Construction Phase Proprietary

Produce1 to 5 - - 20

Operation Phase ProprietaryProduce Consumables

1 to 5 - - 50

Local Fabrication Opportunities 1 to 5 - - 15 Reuse of Existing Structures 1 to 5 - - 15

- - - - Total 1008.2.1.3 Constructability: 1 to 5 5 percent 100

- - - - Total 1008.2.1.4 Effluent Objectives Met Yes/No NA NA

8.2.1.5 O&M Costs: 35 percent Energy Annual Cost in USD - - 55 Chemicals Annual Cost in USD - - 30 Labor Annual Cost in USD - - 10 Others Annual Cost in USD - - 5

- - - - Total 1008.2.1.6 Capital Costs: 15 percent Land Acquisition Required USD - - 0, same for all Electrical Service Upgrade USD - - 0, same for all Construction Contract USD - - 60 Construction Management USD - - 5 Two Years of Contractor O&M USD - - 35

Total 100


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Criteria Process Performance Score

Category Weight

Subcategory Weights

8.2.1.7 Life-Cycle Costs Through 2045: NA NA Ratio of Life-Cycle Costs

8.2.2.4 Scoring Total PointsThe general total points are a summation of the weight performance scores (8.2.1.1, 8.2.1.2, 8.2.1.3, and 8.2.1.4), O&M costs (8.2.1.5), and capital costs (8.2.1.6). The costs were inversely prorated between the highest and lowest cost values in the subcategory; therefore, the lowest cost item received the highest score while the highest cost item received the lowest score. This way, the alternative with the lowest cost has the highest score to correspond with the performance scores where the higher values are favorable.

According to this scoring system, the alternative with the highest number of points is most favorable based on the evaluation criteria and costs, while the alternative with the lowest total points is the least favorable.

The life-cycle cost (8.2.1.7) is not used in the total points.

8.2.2.4.1 Life-Cycle Cost ComparingLife-cycle cost (8.2.1.7) is intended to be an independent evaluation parameter. It is not included in the total points to avoid duplication of the cost categories in the general total points score. The life-cycle costs were inversely prorated so that the alternative with the lowest life-cycle cost has a score of 1.0, while the alternative with the highest life-cycle cost has a score of 0.0.

8.2.3 Sustainability ScoreThe sustainability score identifies key operational parameters that are of particular interest to the plant operators for the long-term sustained operation and management of the facility after construction. The parameters that make up the sustainability score are:

Operational Complexity (8.2.1.1): subcategories of maintenance complexity andchemical requirements

Material Requirements (8.2.1.2): subcategory of operation phase proprietaryconsumables

O&M Costs (8.2.1.5): subcategories of energy and chemicals

As with the general total points and the life-cycle cost comparing, the sustainability score was inversely prorated between the highest and lowest cost values in the subcategory. This way, the alternative with the lowest cost has the highest score to correspond with the performance scores where the higher values are favorable.

According to this scoring system, the alternative with the highest number of points is most favorable, based on the sustainability score evaluation criteria and costs, while the alternative with the lowest total points is the least favorable.


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8.2.4 Conceptual Opinion of Probable Construction CostThe feasibility design conceptual level OPCC, also referred to aa a cost estimate, is an opinion on the cost for construction the WWTP used for comparing alternatives. The OPCC includes the following assumptions:

General condition costs applied at 5 percent

Indirect costs (permits, risk and liability insurance, and bonds) applied at 2.65 percent

Contractor overhead and profit applied at 15 percent

Construction contingency for concept design applied at 30 percent. The constructioncontingency is for uncertainties in the conceptual design, and the contingencypercentage decreases as the infrastructure design progresses and the designuncertainty decreases.

Costs are in present (2020) USD. Cost escalation to mid-point of construction is not included in the OPCC values presented below, but is included in the financial analysis in Section 7. Appendix C (Basis of Cost Estimates) includes construction cost backup for each alternative.

8.3 Evaluation Results and RecommendationsThe treatment process evaluation matrix and worksheet are included in Appendix E. The average annual O&M costs for each alternative in the following section were not updated for from the draft report, see the Executive Summary in this final report for the latest update.

8.3.1 Summary of Costs by AlternativesThe estimated average annual O&M costs and capital costs for each Madaba WWTP expansion alternative is presented in the following series of tables that concludes with a summary listing the life-cycle costs for each alternative. The cost for sludge thickening and dewatering are included in the solid alternatives.

8.3.1.1 Alternative A.1 O&M and Capital CostsAlternative A.1 is the modification of the existing aeration tanks to plug-flow BNR tanks and the addition of new primary and secondary clarifiers, with (1) conventional anaerobic digestion and CHP system for electricity generation from biogas. A major disadvantage of this alternative it that it would require one extra year of construction (4 years in total) because the existing WWTP must remain in operation throughout construction of the expansion and construction staging is required. It is estimated that this will add 5 percent to the construction costs. The estimated comparative total average annual O&M costs for alternative comparing purposes are listed in Table 8-3 and the total construction phase capital costs are listed in Table 8-4.

The 3-year O&M period of oversight by the construction contractor does not include electrical costs and most chemicals.


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The economic analysis (Section 7.2) identified Alternative C.2 as the most cost-effective under the base case assumptions.

Alternatives B and C for liquid-stream treatment are different in their BNR tank configuration, but they are the same biological processes and produce the same effluent quality. The advantages of the oxidation ditch (Alternative B) is simpler operation and less system hydraulic headloss, but even with the submerged aeration system it has a slightly higher electricity requirement. The advantages for the BNR plug-flow tanks (Alternative C) is compact footprint and slightly lower energy requirement than the oxidation ditch.

Alternative A.1 includes rehabilitation of the two existing aeration tanks into two BNR plug-flow treatment trains, plus the construction of two new BNR plug-flow trains. Because the existing WWTP must remain operational throughout construction, the two new treatment trains would be constructed, tested, and then commissioned before the existing tanks could be taken out of service for retrofitting. This phased construction would add at least one year to the project construction duration. Also, the condition of the existing infrastructure can’t be completely assessed while in operation which adds uncertainty to the costs. Reusing the existing tanks also adds operation costs because aeration is not as efficient in shallower tanks. This alternative is not recommended.

Alternatives A.1, B.1, and C.1 include conventional anaerobic digestion and CHP engines to produce electricity; but, of all the treatment processes, this one has the highest level of operational complexity. The cost recovery from the production of electricity from digester gas (biogas) reduces the amount of power that the WWTP purchased from the national electric grid, but CHP systems are the most expensive and complex systems to operate process at a WWTP. Because of the high capital and operational costs of the CHP equipment, it is rarely found to be economical for a WWTP of this size.

Alternatives B.1A and C.1A is the same as Alternatives B.1 and C.1, except the CHP system is not included. The conventional anaerobic digesters are included to treat the sludge and the design would allow for the future installation of the CHP system. This alternative is recommended as a step approach toward energy recovery.

Alternative C.3 includes an aerated sludge holding tank to partly stabilize primary sludge before dewatering and drying. This has a low initial capital cost and allows for the future addition of conventional anaerobic digesters and CHP engines. However, the aerated sludge holding tank requires electricity to power the aeration system, thus the alterative has a high operating cost. This is not a recommended alternative.

Alternatives B.1 and C.1 are recommended if (as a matter of policy) MWI/WAJ requires anerobic digestion with CHP to reduce electricity purchased from the power utility.

8.3.3.1 RecommendationsMWI/WAJ has already rejected the CIGAR concept of Alternative C.2 and prefers energy recovery systems at WWTP to reduce electricity charges.

If MWI/WAJ want to invest in WWTP energy recovery, and if the construction financing is available, then Alternative B.1 (or C.1) is recommended. However, considering the limitations on WWTP construction funds and the need for MWC staff to gain experience with operating a WWTP equipped with conventional anaerobic digestion, a phased approach is


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recommended—Alternative B.1A (or C.1A)—to include the conventional anaerobic digesters with the option to add the CHP system in the future.

As discussed in the Executive Summary, in a letter dated January 21, 2021 the MWI/WAJ and MWC selected Alternative C.1A with the revised construction costs provide during the meeting on December 30, 2020. See the Executive Summary for the latest information regarding this report.


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Section 9Summary of Treatment Recommendations

This section summarizes the alternative selection and the recommendations for the expansion of the Madaba WWTP.

The evaluation of treatment alternatives in Section 8 identified C.2 to be the most maintainable and cost-effective alternative. However, because MWI/WAJ prefers to generate power at WWTPs to reduce O&M costs, this section assumes that MWI/WAJ will select Alternative B.1 (or C.1), very similar to the recommended Alternative B.1A (or C.1A) for the 2045 plant capacity of AADF of 16,000 m3/d and biological loading of 13,010 kg/d as BOD5.

The drawings from Appendix D relevant to Alternative B.1 are:

Drawing No. C-MA-2 Alternative B.1 – Site Plan

Drawing No. M-MA-2 Alternative B – Process Flow Diagram

Drawing No. M-MA-5 Alternative 1 – Process Flow Diagram

The following paragraphs provide greater detail regarding the specific parts of the proposed plan expansion. Suggestions are made for some process requirements while other sections within this report justified the recommended technologies. For most processes, a technology analysis will be performed in the Basis of Design Report to following this feasibility report.

Design of upgrades and new facility includes the following:

Headworks new components with rock trap, screening, grit removal, flowmetering, and diversion to influent stormwater management (previously known as equalization) ponds

Maintain emergency bypass to wadi diversion structure and flowmetering, screenings, and grit removal

Maintain connection to influent stormwater ponds and upgrade of diversion chamber

Primary clarifiers with primary sludge pumping

New BNR process tanks (oxidation ditches)

No conversion and rehabilitation of existing aeration tanks, except for Alternative C.3

New secondary clarifiers

RAS and WAS conveyance systems

New disinfection system

Rehabilitation of the sludge thickening

Section 9 Summary of Treatment Recommendations

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Rehabilitation of the sludge drying beds (sludge dewatering) and addition of new sludge drying beds

Sludge stabilization with anaerobic digester

Odor control, as needed

Yard piping

Site work, including all utilities

Power supply system and full standby power to maintain plant operation during power outages

Fire water system around anaerobic digestion and CHP system, if any

Administration building with maintenance, laboratory, and operations

Instrumentation and control systems

Upgrade or rehabilitation of existing polishing ponds is not included

The following provides minimal design criteria for the different process components listed above. Details provided will guide the development of the Basis of Design Report including worker protection and safety requirements as required by Regulation Number 43 of the Year 1998, The Regulation of Protection and Safety from Industrial Tools and Machines and Work Sites.

8.4 General Liquid Treatment Stream Design CriteriaThe plant expansion will require similar preliminary processes to the existing facility, including an influent flow overflow structure, rock trap, flow measurement, screening, and grit removal.

The following provides a few technical details regarding the different processes being considered for the new headworks system.

The following criteria assumes the selection of liquid-stream treatment Alternative B.1 for a plant with an ADF of 16,000 m3/d in the project design horizon year of 2045.

8.4.1 Plant HydraulicsThe preliminary plant hydraulic profile is shown in Drawing No. G-MA-04. For the feasibility study, the hydraulic profile for Alternative C was selected to be represented in the report because it was considered to have the highest head requirements of the four liquid-stream treatment alternatives evaluated. The future basis of design report will have an updated hydraulic profile for the selected alternative.

8.4.2 Septage Unloading StationThe existing septage unloading station is heavily utilized and presents health risks because of the considerable splashing that occurs during truck unloading of the septage. Also, there is no odor control for the area, and the odors are very strong during unloading. A new station with odor control is recommended.


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The recommended replacement septage unloading station would be similar to the septage unloading station at the South Amman WWTP, shown in Figure 9-1, and would include the following:

Connection to the headworks odor control system

Separate truck entry and exit so all the trucks drive through in one direction and do not have to turn around or back up like at the current Madaba WWTP septage unloading station

Require truck to unload using their flexible hoses to avoid the unsanitary splashing of septage experienced at the existing station

Hose holes where the trucks will insert their flexible hose to be at the edge of the containment area, so the hose does not need to be so long, and the driver does not have to enter the containment area. This is unlike the South Amman WWTP station, which has the hose holes in the center of the containment area.

Allow for two or more trucks to unload at one time with space for trucks to line up behind while waiting to unload


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Figure 9-1Septage Unloading Station at South Amman WWTP

New septage unloading station general criteria is listed in Table 9-1.

Catch basin

Truck Hose Opening

Odor Control Piping


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Table 9-1 Septage Unloading Station

Parameter Unit ValueTruck unloading stations each 2

Trucks per day (15 m3 per truck) each47 (in 2018)26 (in 2045)

Septage quantity m3/d 400 (in 2045)

Odor control – Connect to headworks system

Number of screening units each 1

Screen size mm 5 (depends of selected Alternative)

Septage sent to –Anerobic digestion via primary sludge screening and thickening

8.4.3 Rock TrapGravel and rock (from the collection system) are washed into the WWTP following a rain storm when influent flow is high because stormwater has entered the sewer and mixed with the sewage, which is a common problem for the headworks of municipal WWTPs in Jordan. To help mitigate this problem, a new rock trap will be installed upstream of the influent screens. The rock trap will include the following features:

Rock pit for the collection of gravel and rock

Small clamshell bucket with electric hoist mounted on a monorail for removing the gravel and rocks from the pit

Rock-draining pad

Dry weather bypass

Rock trap tank overflow to headworks

8.4.4 Bypass to Wadi The expanded WWTP will maintain use of an existing bypass to wadi to convey peak influent flows in excess of the WWTP hydraulic capacity directly to the wadi. The proposed peak hydraulic capacity for the expanded plant is 40,000 m3/d (2.5 × ADF) and flow in excess will be diverted to the influent stormwater management ponds. After the stormwater management ponds are full, the excess flow is diverted to the wadi.

8.4.5 Influent Screening Three variations of screen are recommended to be used in series—a manual bar screen (or manual bar rack) with 50 mm openings located directly downstream of the rock trap followed by mechanical bar screens with 25 mm (coarse screen) and screens with 6 mm openings (fine screen). For each screen type, two screening channels are recommended, each with a capacity for one-half (50 percent) of the peak flow: 40,000 m3/d, or 20,000 m3/d per screen. A bypass channel will also be provided around the mechanical screens, equipped with an upstream slide gate to allow for a passive overflow into the bypass channel in the event the mechanical screens malfunction. This provides firm capacity at peak flow, while providing a means to take


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a screen out of service for maintenance during dry weather periods. As discussed in Section 6, the multi-rake style bar screen is recommended for the 25 mm and 6 mm screens.

Because the coarse screens will collect larger debris, it is recommended to convey the coarse screenings to the container (dumpster) using a screw conveyor. The fine screen will collect smaller debris that may have the potential for containing a significant amount of organic material. Therefore, it is recommended that each fine screen be equipped with a screening washer compactor.

8.4.5.1 Manual Bar Screen Number of units: 2

Type: Manually cleaned bar rack

Capacity per unit, m3/d: 20,000

Bar spacing (clear), mm: 50

Bar width, mm: 10

Bar depth, mm: 40

Angle from horizontal: 75°

Operation: 2 duty

Screenings (m3/day) 0.1 at ADF, 0.2 at PHF

8.4.5.2 Coarse Mechanical Screens Number of units: 2

Type: Multi-rake, mechanically cleaned


Clear spacing, mm: 25

Operation: 2 duty

8.4.5.3 Coarse Screenings Conveyor Number of units: 1

Type: Shaftless screw conveyor

Capacity per unit, m3/d: 0.4 at ADF; 1.0 at PHF

Operation: 1 duty for both screens

8.4.5.4 Fine Mechanical Screens Number of units: 2

Type: Multi-rake, mechanically cleaned



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Clear spacing, mm: 6

Operation: 2 duty

8.4.5.5 Fine Screenings Washer Compactor Number of units: 2 (one per screen)

Type: Screw press with wash and pressure zones

Capacity per unit, m3 screenings/d: 0.6 at ADF, 1.4 at PHF

Operation: 1 per fine screen

8.4.5.6 Screenings Containers No. of screening containers: 2

Volume, m3: 3 to 5

8.4.6 Flow Measurement (Parshall flume) Parshall flumes have been used successfully in wastewater treatment plants for many decades and are still the industry standard for open channel flow measurement. The flumes themselves have no moving or electronic parts. The level instrument located above the flume is the only component that requires power, and the instrument can be easily replaced by plant staff if it begins to malfunction.

Two 305 mm (throat width) flumes are recommended to provide redundancy. Because the average daily flow at plant start-up may be as low as 6,400 m3/d, it is important to size the flume to maintain accuracy at lower flows. Each 305 mm flume has a rated capacity of approximately 40,000 m3/d.

8.4.6.1 Parshall flumePlant flow measurement with Parshall flume.

Number of units: 2

Throat width, mm: 305 mm (12 inch)

Allowable flow range, m3/d: 294 to 40,000

8.4.7 Influent Stormwater ManagementInfluent stormwater management is necessary to temporary store wet weather flow combined with sewage that often exceed the design treatment capacity of the WWTP and avoid bypassing this excess flow to the wadi. After the peak wet weather flows pass, the raw wastewater in the influent stormwater ponds is pumped back to the headworks for treatment. The existing equalization basins will be rehabilitated for use as influent stormwater management ponds and their capacity will be expanded, as necessary.

The influent stormwater pond capacity criteria used by Yarmouk Water Company (YWC) for their WWTPs is a minimum one-day average design capacity, which for Madaba WWTP would be 16,000 m3 of usable storage volume.


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8.4.8 Grit and Grease Removal As discussed in Section 5, the aerated grit and grease removal system is recommended because it is the technology that WWTP operators in Jordan are most familiar with. The design will include two units to reach firm capacity without a standby unit plus a bypass channel. Therefore, it is recommended to install two aerated grit and grease chambers, each with a design capacity of 20,000 m3/d, for a total capacity of at least 40,000 m3/d peak design flow.

8.4.8.1.1 Grit and Grease Chambers Number of units: 2

Type: Aerated grit and grease

Capacity per unit, m3/d: 20,000 (minimum)

Operation: 2 duty

Bypass channel, m3/d 40,000 (minimum)

8.4.8.1.2 Grit PumpsEach grit chamber should be equipped with one duty and one standby grit pump, similar to the Wemco Model C pump, with a recessed impeller for conveyance of grit slurry.

8.4.8.1.3 Grit Classifier Number of units: 2 (one per grit chamber)

Type: Wemco Model C or equal

Operation: 2 duty (one per grit chamber)

8.4.8.1.4 Classifier Wash Water ReturnIf a grit classifier is located near grade, washwater will be returned to the influent pump station. If the classifier it elevated above the grit chamber floor, the washwater should be returned to the grit chamber influent channel.

8.4.8.1.5 Grease Conveyor Number of units: 2 (one per chamber)

Type: TBD

Capacity per unit, m3/d: TBD

Operation: 2 duty (one per chamber)

8.4.9 Odor Control 8.4.9.1 Headworks Odor Control SystemAs discussed in Section 6, the two technologies considered for the headworks include biotrickling filters and biofilters. H2S is the predominant odor compound at the head of a wastewater treatment plant, and both technologies will remove H2S successfully (> 90 percent removal). However, a biotrickling filter is better at handling spikes of H2S concentration and better suited to treat high H2S streams. Furthermore, a biotrickling filter is currently


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successfully being used at the East Jerash WWTP. Therefore, it is recommended to proceed with the design of a biotrickling filter for headworks odor control.

For this study, it is presumed that the headworks will be ventilated at a rate of 12 air changes per hour (ac/h), which replaces the airspace within a structure 12 times in 1 hour. The estimated airspace exhaust airflow rates, in m3/h, are as follows:

Screening equipment and channels: 2,000 m3/h

Grit and grease chambers, Parshall flume, and effluent channel: 3,500 m3/h

The aforementioned airflow results in a total airflow of 5,500 m3/hr. At this stage in design, a safety factor of 30 percent will be applied, resulting in a design airflow of 7,200 m3/h for the odor control system.

Type: Biotrickling filter

Number of Vessels (towers): 1

Number of exhaust fans: 1 duty and 1 standby

Design airflow: 7,200 m3/h

Media type: synthetic structured media

Design H2S removal: > 90 percent

Vessel material: Fiberglass

8.4.9.2 Septage Unloading and Solids Handling Odor Control SystemsWhile the odor control systems that serve the septage receiving and solids handling areas will be further developed in the design phase, the following includes some conceptual design criteria. For consistency with the headworks odor control system, biotrickling filters are also recommended here. During the design phase, if desired, other technologies can be examined in further detail.

Estimated septage and solids odor sources and exhaust flow rates are listed below, assuming 12 ac/h for septage unloading and 6 ac/h for digester feed tank (thickened WAS storage at near empty) and gravity thickeners (primary sludge thickening).

Septage unloading station: 700 m3/h

Digester feed tank: 1,800 m3/h

Gravity thickeners: 500 m3/h

Because of their close proximity, odorous air from the septage unloading station and digester feed tank can be treated together with a single odor control system. Also, during the design phase, combining these sources with the headworks or the gravity thickeners could be considered for reducing the number of odor control systems; however, the ductwork may require significant lengths. At this stage, the systems are described separately to be conservative. Refer to the following lists for conceptual design criteria for these systems. The design flows include a 30-percent safety factor.


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Septage Unloading/Digester Feed Tank Odor Control System


Number of vessels (towers): 1


Design airflow: 3,300 m3/h

Media Type: Synthetic structured media



Gravity Thickener Odor Control System


Number of vessels (towers): 1


Design airflow: 700 m3/h

Media type: Synthetic structured media



8.5 General Solids Stream Design CriteriaThe following criteria assumes the selection of solids stream treatment Alternative 1 that was selected by MWI/WAJ. This alternative comprises conventional anaerobic digestion with CHP for electric power generation and is the most complex and expensive system to operate and maintain at a WWTP. It involves complex biological processes and requires highly trained operators know the process and can troubleshoot biological process and mechanical problems. Because of the operational complexity of these systems and the current WWTP operation standards in Jordan, this technology may not be a sustainable option for Jordan at the present time. However, with strong and continued commitment from MWI/WAJ and continued financial and technical support from donors, the conditions in Jordan can change to make this WWTP option more sustainable.

8.5.1 Sludge Stabilization As described in Section 5, one of the most common and proven technologies used for stabilization (pathogen, odor reduction) of biosolids used around the world is conventional anaerobic digestion, which involves heating sludge to mesophilic temperatures under anaerobic conditions to biologically reduce volatile solids. Although sludge stabilization is not required for third-class biosolids, it is a side benefit of energy recovery from biosolids.


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8.5.1.1 Sludge FeedTo maintain smooth biological processes and prevent digester upsets, the digester needs to be fed as uniformly and consistently as possible by pumping the feed streams on a near-continuous cycle or continuous basis. A blending tank can typically provide a wide spot to help with this process. However, to save cost and minimize additional phosphorus release when primary sludge and WAS are mixed in absence of DO, a blending tank is currently not proposed.

Additionally, the pumps for each thickened sludge stream should operate on a VFD for operational flexibility. Note, intermittent pumping will be required to keep minimum recommended sludge velocities and minimum recommended diameter piping. This report considers a minimum velocity of 0.3 meters per second (m/s) and a recommended minimum velocity of 0.6 m/s, as well as a recommended minimum pipe diameter of 100 mm to mitigate clogging.

The projected thickened sludge (thickened primary sludge and septage from gravity thickeners, and thickened WAS from gravity belt thickeners) flows and loads are shown in Table 9-2.

Table 9-2 Thickened Sludge Flows and Loads

Parameter Unit Minimum Day

Average Daily

Maximum Month

Peak Two-Week

Thickened Primary Sludge and Septage

Flow m3/d 122 128 136 160 Dry Solids Load dry kg/d 3,798 5,894 7,528 8,841 Solids Concentration Percent (%) 3.1 4.6 5.5 5.5Thickened WAS (GBT) Flow m3/d 95 106 127 160 Dry Solids Load dry kg/d 3,790 5,609 6,668 8,401 Solids Concentration Percent (%) 4.0 5.3 5.2 5.2

Conceptual thickened sludge pumping criteria are listed in Table 9-3. The flow rates have been conservatively sized to maintain a minimum velocity of 0.6 m/s for sludge flow. Note, these flows exceed peak week values; thus, this will require pumping intermittently, and effective sequencing is recommended to achieve consistent feed cycling to the digesters. As discussed in Section 5.3, progressive cavity pumps are positive displacement pumps and appropriate for pumping thickener sludges. Flooded suction is recommended. Thus, depending on the operating and draining levels of the gravity thickeners and digester feed tank (thickened WAS, storage) the pumps could be installed in a vault or a building basement.

Table 9-3 Thickened Sludge Pumps

Parameter Unit ValueThickened Primary and Septage Pumps Type and Drive – Progressive cavity with VFDs Number duty/standby 1/1 Flow (each) m3/d 414 Load (each) kW 4Thickened WAS Pumps Type and Drive – Progressive cavity with VFDs


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Parameter Unit Value Number duty/standby 1/1 Flow (each) m3/d 414 Load (each) kW 4

8.5.1.2 Anaerobic Digester TanksTwo anaerobic digester tanks are proposed and were sized to accommodate the 2045 ADMM loads at a minimum SRT of 18.5 days. Additionally, maximum loads should not exceed 2.9 kg VS/m3∙d to prevent overloading to the digesters and mitigate upsets. As determined per Section 5.3, for Madaba WWTP, cylindrical concrete construction is proposed with fixed-steel covers. For cylindrical reactors, it is imperative that the tanks not be too shallow, which can inhibit effective mixing. For this reason, the digesters were initially sized to have the same diameter and SWD. During final design, this can be optimized from a structural perspective and based on the WAJ’s preference for tank height.

Tables 9-3 and 9-4 summarizes key anaerobic digestion design criteria and flows and loads, respectively.

Table 9-3 Anaerobic Digestion Design Criteria

Parameter Unit ValueNo. of Digesters – 2Minimum SRT at Maximum Month d 18.5Diameter m 15SWD1 m 14Temperature °C 35VSR2 Percent (%) 50Gas Production Rate m3/kg VSR 0.94Construction – Cylindrical concreteCover – Fixed steelMaximum Operating Gas Pressure 30 mbar

1 Total wall height adds 1.5 m of freeboard onto SWD.2 60 percent presumed for primary sludge and septage, and 40 percent presumed for WAS.

Table 9-4 Anaerobic Digestion Flows and Loads


Average Daily

Maximum Month

Peak Two-Week

Combined Flow to Digesters m3/d 217 234 263 320Combined Solids Load to Digesters dry kg/d 7,594 11,512 14,207 17,242Combined Solids Concentration to Digesters Percent (%) 3.5 4.9 5.4 5.4Solids Retention Time d 23 21 19 15Solids Loading kg VS/ m3∙d 1.1 1.7 2.1 2.5Digested Sludge Flow m3/d 217 234 263 320Digester Sludge Load dry kg/d 4,817 7,299 9,066 11,048Digested Sludge Concentration Percent (%) 2.2 3.1 3.4 3.4

Like thickened sludge pumps, the digested sludge withdrawal pumps are proposed as progressive cavity pumps (Table 9-5) and will need to be configured for flooded suction. During final design, further evaluation will determine whether these pumps will be located in a vault or in a basement beneath the Digester Operation Building.


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Table 9-5 Digester Withdrawal Pumps

Parameter Unit Value Type and Drive – Progressive cavity with VFD Number duty/standby 1/1 Flow (each) m3/d 414 Load (each) kW 2

8.5.1.3 Digester Mixing SystemAs discussed in Section 5.3.1, two systems could be appropriate for the Madaba WWTP, including external pump (recirculation) mixing and mechanical (linear motion) mixing. For the purposes of this evaluation, linear motion mixing is shown below based on its lower electrical load compared to pump mixing. Only linear mixing systems with all major maintenance components external to the tank would be considered. Table 9-6 summarizes the digester mixing design criteria.

Table 9-6 Mechanical Linear Motion Mixing Design Criteria

Parameter Unit ValueType – LinearDead Weight per Tank 2,400 kgMax Dynamic Load 1,300 kgNo. of Mixers per Tank – 1Load kW 6

8.5.1.4 Digester Recirculation and Heating SystemAs common with new digesters, the proposed digesters will be heated using external sludge heat exchangers and recirculation pumps. The hot water will be sourced from the CHP heat recovery system or backup boiler(s). Table 9-7 presents the recirculation and heating system design criteria.

Table 9-7 Digester Recirculation and Heating System Design Criteria

Parameter Unit ValueRecirculation Pumps Type – Chopper Number duty/standby 2/2 Flow (each) m3/h 57 Load (each) kW 6Heat Exchangers Type – Tube-in-tube Number duty/standby 2/0 Sludge Flow (each) m3/h 57 Sludge Tube Diameter Mm 100 Hot-Water Flow (each) m3/h 34 Hot-Water Tube Diameter mm 100 Heat Transfer (each) kW 387


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8.5.1.5 Digested Sludge Storage TankThe digested sludge withdrawal pumps will discharge into a digested sludge storage tank. Designed for a retention time of 2 days, the digested sludge storage tank will be sized per design criteria presented in Table 9-8. As discussed in Section 5.3.1, for simplicity, external mixing pumps with a design turnover rate of 4 hours are proposed. Construction is proposed to be similar to the digester tanks, with the headspace connected to the digester gas collection system.

Table 9-8 Digested Sludge Storage Design Criteria

Parameter Unit ValueDigested Sludge Storage Tank Minimum SRT at Maximum Month d 2 Diameter m 9.0 SWD1 m 8.7 Construction – Cylindrical concrete Cover – Fixed steel Mixing Turnover Rate H 4Mixing Pumps Type – Chopper Number duty/standby 1/1 Flow (each) m3/h 132 Load (each) kW 15Mixing Nozzles Number – 2

1 Total wall height adds 0.6 m of freeboard onto SWD.

8.5.2 Digester Gas SystemA key driver for the implementation of anaerobic digestion systems is the production of biogas and its beneficial reuse for renewable energy, such as electricity and process heating. To fully understand the benefit of biogas utilization, quantified projected biogas generation is shown in Table 9-9. For the solids loadings discussed in the previous section, a typical biogas production rate of 0.94 m3/kg VSR was presumed. Table 9-9 includes maximum day load conditions, which are important for sizing digester gas piping and checking system pressures. Assuming a low-pressure operating pressure of 30 mbar, the main digester gas collection header should be sized 150–200 mm in diameter as 316L stainless steel pipe.

Table 9-9 Digester Gas Production


Average Daily

Maximum Month

Peak Two-Week

Maximum Day

Gas Production m3/h 108 164 201 242 286Gas Production m3/d 2,602 3,947 4,817 5,804 6,871

8.5.2.1 Excess Gas FlareExcess gas flares provide a means for releasing waste gas safely into the atmosphere in a controlled manner. While 100 percent of the digester gas is expected to be used by the CHP system to produce electricity and to process heating, if the CHP system goes down, the backup boiler(s) and flare provide avenues for utilizing and releasing gas, respectively. Because the flare acts as a backup to the overall system, only one candlelit flare is currently proposed. The flare is generally controlled off pressure, using a pressure relief and flame trap type assembly.


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Upon sensing a high-pressure setpoint, the assembly releases waste gas to the burner. Table 9-10 summarizes the flare design criteria.

Table 9-10 Excess Gas Flare Design Criteria

Parameter Unit ValueType – Open candlelitNumber duty/standby 1/0Flow m3/h 300Manifold Size mm 150Turndown – Infinite Height1 m 4

1 Not including mounting foundation

8.5.2.2 Gas Storage Holder A gas storage tank is proposed to provide operational flexibility in the gas collection system. The industry standard is double-membrane-type gas holders, as discussed in Section 5.3. However, a membrane-fixed-enclosure is recommended because of the warm temperatures and high sun intensity; this can be further considered during the design phase. Assuming a storage volume based on the average daily flow of 4 hours of storage, the following design criteria, including gas storage holder design, are shown in Table 9-11.

Table 9-11 Gas Storage Holder Design Criteria

Parameter Unit ValueType – Double-membraneStorage Time at ADF H 4Storage m3 700Diameter M 10Height M 9.2Shape – ¾ SphereOperating Pressure mbar 30Mounting – Slab-mountedNo. of Air fans duty/standby 1/1Fan Load kW 2.5

8.5.3 Digester Gas Energy Recovery SystemTo turn biogas into electricity and to process heating for the Madaba WWTP, the produced biogas will be routed through a digester gas cleaning to condition the gas for use at the engine generators and backup boiler(s), as discussed below.

8.5.3.1 Gas Cleaning System As discussed in detail in Section 5.3, moisture and contaminant removal are important for prolonging the engine’s life. The gas must be compressed to provide the required pressure at the engine and boiler systems. For the Madaba WWTP, a packaged system provided by a single supplier is recommended for consistency and simpler operation. During final design and further discussion with MWI/WAJ and MWC, design system optimization to meet operational capabilities and access to manufacturer services will be considered further. The packaged system can be provided as a containerized building or mounted on a skid and located under a canopy or in the Digester Operation Building. This evaluation has initially


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presumed the system to be located within the Digester Operation Building, except for the H2S and siloxane removal vessels.

Table 9-12 summarizes the initial design criteria for the gas cleaning system. Currently, the system is sized for peak two-week loads; however, with gas storage capabilities, potentially this could be reduced to maximum month loads.

Table 9-12 Digester Gas Cleaning System Design Criteria

Parameter Unit ValueGas Compression Type – Multistage on VFD Number duty/standby 1/1 Flow (each) m3/h 242 Load (each) kW 2 Discharge Pressure Bar 0.2Moisture Removal Type – Shell in tube heat exchanger Number duty/standby 1/0 Cooling Temperature °C 4 Chiller Load kW 25H2S Removal Type – Cylindrical reactors with media Number Duty/standby 1/0 Flow (each) m3/h 242 Design Inlet H2S ppm 2001

Design Outlet H2S ppm 2Siloxane Removal Type – Cylindrical reactors with media Number Duty/standby 1/1 Flow (each) m3/h 242 Percent Removal percent 99Overall Footprint Dimensions m (L x W) 15 × 12

1 Assumes ferric is dosed in the digesters.

This evaluation includes both ferric addition (to the sludge), which can remove H2S within the sludge, and gaseous H2S treatment. In reality, only one mechanism may be necessary; however, both have been included for operational flexibility because ferric may be required for other uses (such as struvite management) or less chemical usage may be desired. For purposes of this evaluation and life-cycle costs, it is presumed that ferric would be dosed for dissolved H2S removal in the digesters and, thus, less media change out (carbon-based or iron oxide type) would be required in the gaseous phase. Based on further investigation on media availability, H2S loadings, and operator preference, little or no ferric may be required.

8.5.3.2 Combined Heat and Power Gas Engine SystemAs discussed in Section 5.3, a packaged gas reciprocating or internal combustion engine system with heat recovery is recommended for location in the Digester Operation Building. During final design and further discussions with the WAJ and MWC, design system optimization to meet operational capabilities and access to manufacturer services will be considered in more depth for the digester gas cleaning system. Additional engine sizing and consideration will be needed with regards to the expected, relatively low, gas flows, the


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typical engine sizes, and the expected continuous turndown. Furthermore, a third engine could be provided for partial or full redundancy. Tables 9-13 and 9-14 summarize the design criteria for the CHP engine system and energy generation, respectively.

Table 9-13 Digester Gas Combined Heat and Power Design Criteria

Parameter Unit ValueBiogas Heating Value kJ/m3 22,355Type – Reciprocating with heat recoveryNumber of Engines duty/standby 2/0Electrical Efficiency1 percent 39Electrical Output (each)1 kW 330Heat Efficiency1 percent 46Heat Output (each)1 kW 395Turndown percent 50Required Pressure bar 0.2System Dimensions m (L × W × H) 12 × 7 × 3

1 Based on Jenbacher Type 2 Engine

Table 9-13 is based upon Jenbacher’s smallest engine. Note, alternate manufacturers, such as 2G, have smaller engine sizes. Utilizing a smaller engine size may be necessary to account for low-flow turndowns. This will be investigated further during final design.

Table 9-14 Digester Gas Electrical and Heat Generation

Parameter Unit Start-Up Minimum Day

Average Daily

Maximum Month

Peak Two-Week

Biogas Fuel kW 490 673 1,021 1,246 1,502Generated Electricity1 kW 191 263 398 486 586Annual Electricity2 MWh/y 1,675 – 3,489 – –Generated Heat3 kW 229 314 477 582 701

1 Accounts for electrical efficiency of engine. 2 Accounts for a CHP runtime of 97 percent. 3 Accounts for heat efficiency and turndown of engine for electrical generation.

As shown in Table 9-14, annual average electrical production value is projected to range from approximately 1,675 MWh at start-up to 3,489 MWh at average day flow in 2045. These numbers do not subtract out any electrical usage associated with operating the conventional digestion and digester gas utilization systems themselves.

All process heating required for the digesters will be covered by the CHP heat recovery system. If the CHP system is off-line for maintenance, a backup boiler is proposed for heating the digesters (to be located in the Digester Operation Building). The design criteria for the backup boiler are presented in Table 9-15. If desired for redundancy, two boilers could be provided.

Table 9-15 Digester Gas Backup Boiler Design Criteria

Parameter Unit ValueType – Hot water fire tubeHeat Output Capacity1 kW 530Required Pressure bar 0.1Approximate Dimensions m (L × W × H) 4 × 2 × 2

1 If preferred, two boilers at 400 kW output could be provided for redundancy, at minimum, at average day conditions.


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8.5.4 Sludge Dewatering in Drying Beds8.5.4.1 Existing Drying BedsThe Madaba WWTP currently has 14 drying beds that provide a total drying area of 20,000 m2. Drying is achieved from sun exposure and ambient conditions. Thickened sludge is conveyed to the drying beds via distribution channels. Filtrate from the drying beds is sent to the excess water tank before ultimately returning to the biological treatment processes. The sludge in the beds reaches a thickness of 200 mm. Sludge drying time is dependent upon weather conditions; however, this thickness provides an average drying time of approximately 3 weeks.

With the WWTP expansion to an influent AADF of 16,000 m3/d by 2045, the WWTP will need additional drying bed area. The amount of the additional drying bed area will be determined and included in the BODR.

8.5.4.2 New Drying BedsNew drying beds with supernatant decant mechanisms will be added to or replace the existing drying bed area at the plant.

Operators will apply multiple (as many as feasible) wet sludge additions to a single hard bottom evaporation bed to better consolidate solids for a thicker final dried sludge cake depth. The goal is to make more than one fill/dry application to the bed so that, after final drying, the bed has at least 10 cm of dried sludge of at least 20–30 percent solids, but optimally 40–50 percent solids. This also serves to minimize the number of dried sludge removal events. Table 9-16 provides an example of this type of operation.

Table 9-16 Example of Using Multiple Drying Bed Fill/Dry Cycles

Day Action

1 Fill bed with 30 cm wet sludge.

2 to 4 Decant 5 to 10 cm of supernatant if conditions allow.

5 to 10Evaporation of water ongoing. Bed sludge depth is lowering more each day. The rate is dependent upon air temperature, wind, humidity, precipitation, any additional decanting events, and bed surface raking of any top crust.

11 to 30 If sludge depth has reduced to 10 cm (wet, not dried cake consistence), it is acceptable to apply a subsequent fill to 30 cm.

Decant chambers will implement a mechanical downward acting weir gate as well as a mechanical scum baffle weir gate ahead of the decant gate. To keep the surface floating sludge from getting mixed with the center decant layer, an easily adjustable underflow baffle ahead of the decant weir will be installed. Decant liquor will be variable; at times relatively clean, but with heavy solids content if the decant gate and baffle gates are not monitored by staff.

8.5.5 Mechanical Sludge DewateringA screw press is a simple, slow-moving, mechanical device. The screw press dewatering is continuous and is accomplished by gravity drainage at the inlet end of the screw, then by reducing the volume as the material being dewatered is conveyed from the inlet to the discharge end of the screw press. Proper screw design is critical because different materials


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require different screw speeds, screw configurations, and screens to dewater to a high outlet consistency while maintaining an excellent capture rate.

8.5.6 Sludge DisposalDried sludge is disposed on-site in excavated trenches without improvements necessary for permanent disposal because the only landfill currently accepting WWTP sludge/biosolids is the Al-Akaider landfill and the hauling charges became too much for the WWTP.

The identity of a permanent sludge disposal landfill for Madaba WWTP sludge is not included in the scope of this study, but should be a high-priority study for MWI/WAJ to reduce the risk on soil and groundwater contamination around the Madaba WWTP site. Two possible options for MWI/WAJ to consider include:

Design and construction of a permanent on-site sludge disposal facility on the Madaba WWTP

Regional permanent sludge disposal landfill that would receive WWTP sludge from South Amman and Madaba WWTPs

8.5.7 Ancillary Processes and Support SystemsThe following ancillary equipment and support systems are required for the construction of the WWTP:

Plant water system

Chemical storage and feed systems, if required

Process control gauges and meters

Limited SCADA system

Electrical service and distribution

Fire protection and alarm, lightening system, and security system

Plant rolling equipment, including small loader (Bobcat) for drying bed cleaning

Sludge drying bed management equipment

8.6 Plant Support FacilitiesSupport facilities for the WWTP operations are discussed in this section.

8.6.1 BuildingsThe WWTP support structures for the site include:

Administration building for manager and staff offices, operations room, public reception and meeting rooms, locker rooms, and laboratory

Electrical and generator building for plantwide electrical equipment and emergency standby diesel generator


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Maintenance building for working of plant equipment and storage of spare parts and equipment

8.6.2 General Site CivilGeneral site civil requirements of the WWTP include:

Site roads

Yard lighting

Boundary fencing

Electrical and instrumentation conduits

8.6.3 Maintenance of Plant OperationsThe tender documents will require the contractor to maintain operation of the existing WWTP until commissioning of the new WWTP is complete. Maintenance of plant operations (MOPO) will be complicated during the transfer of flow from the old to new WWTPs. MOPO of sludge processing and disposal will be complicated because of the desire to abandon the drying beds for process tanks. A new and independent power supply will be required from the beginning so as not to overload the existing supply during commissioning of the new WWTP.

8.7 Reuse of Existing Plant InfrastructureThis section discusses options for the reuse or repurposing of existing plant infrastructure and makes recommendations. The main plant infrastructure has been in service since 2002 and much of the concrete work remains in good condition, including process tanks, but the existing process tanks may not be suitable for use in the expansion of the WWTP. Additionally, the ability to reuse existing structures in the plant expansion is hampered by the need to keep the existing WWTP operational and treating wastewater during the construction of the new expanded facility.

8.7.1 Existing Aeration TanksThe existing two parallel aeration tanks are currently rated to provide a total of 3,800 m3/d ADF treatment capacity. Each aeration tank has a side water depth of 4.5 m and is equipped with six platform-mounted surface aerators. The tank has a small anaerobic zone at the head of the basin in a separate tank for EBPR and improved SVI for better settling sludge. The existing electrical support system is significantly degraded by corrosion; therefore, replacement of all the electrical is necessary and the mechanical equipment is near the end of its useful life and should be replaced.

Preliminary evaluation indicated that the SWD of 4.5 m is deep enough to make the fine-bubble-diffused aeration system more efficient than the surface aerators. In addition, retrofitting the existing aeration tanks with fine-bubble-diffused aeration is a better approach from the capital cost standpoint that common process air blowers can also serve both the existing aeration tanks and new BNR trains.

Alternative A considered the reuse of the existing aeration tanks in the expanded plant design for BNR process tanks, but this alternative is not recommended, as discussed in Section 8,


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which may or may not include primary sedimentation depending if anaerobic digestion will be added to the plant as well. The tank upgrade would include the following:

Cleaning out and landfilling the accumulated sludge and grit

Replace existing surface aerators with fine-bubble-diffused aeration system

Demolish the baffle wall between the anaerobic and aerobic zones to prevent aerated water from mixing back into the anoxic zone

Add new anaerobic and anoxic zones before the existing aeration basins

Partition the end of the existing aeration basins to crease post-anoxic and reaeration zones

Add internal recirculation pumps and piping from the aeration tanks to the anoxic zone, which is currently missing from the plant

Replace all electrical wiring and cable trains

Replace all process instrumentation

Rehabilitation of the plant water system

Repair and patching of tank concrete

8.7.1.1 Repurposing Aeration Tanks The aeration tanks could be repurposed for other uses, these will be considered during preliminary and detained design. Opportunities may include:

Foundation for other structures

Remove walls and reuse footing

Build administration building on top and use tank area for workshop and storage

Effluent water storage

Sludge storage – significant modification required

8.7.2 Existing Secondary ClarifiersThe two existing secondary clarifiers are rated to provide a total of 7,600 m3/d ADF treatment capacity. These secondary clarifiers have a diameter of 22 m and a side water depth of 3.1 m. Like the aeration tanks, the concrete work is in good condition and appears suitable for reuse. The mechanical systems are working but are most of the way through their useful life and should be replaced for the plant expansion.

The clarifiers are shallow for secondary clarifiers. Current WWTP design best engineering practices recommend a minimum side water depth of 3.7 m, but preferably 4.3 m. The existing clarifiers are shallow and would have to be derated to 75 percent of their current capacity, which is why reusing them as secondary clarifiers is not recommended. State-point analysis performed suggested that the existing two 22 m diameter secondary clarifiers can provide a total of 10,600 m3/d ADF treatment capacity, which is substantially larger than the current


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rated treatment capacity of 7,600 m3/d ADF. To account for the side water depth limitation, the capacity of these clarifiers may be reduced by 25 percent, which would reduce total treatment capacity to 8,000 m3/d. Therefore, the existing two clarifiers can provide approximately one-third of the proposed plant expansion capacity of 16,000 m3/d. The addition of two new secondary clarifiers to the existing secondary clarifiers can provide the required treatment capacity for the plant expansion.

Updating of the secondary clarifiers in the expanded plant would include:

Rerating the capacity of each clarifier to 1,900 m3/d

Replace mechanical equipment, including the sludge rake, skimmer, larger inlet well, and traveling bridge

Concrete repair and patching

Replacement of sludge pumps

Replace process instrumentation

Upgrade electrical wiring and wiring support, as needed

Rehabilitate plant water system

Rehabilitate scum system

Cleaning and inspection of all sludge lines

Cleaning and repair of the weir and replacement of scum guard

8.7.2.1 Repurposing Secondary ClarifiersOptions for repurposing the existing secondary clarifiers to be considered during detailed design includes:

Sludge gravity thickener tanks

Digested sludge storage tanks

Effluent storage for plant water system

8.7.3 HeadworksThe existing headworks do not have the capacity or flexibility to be expanded to the 2045 projected flows of 16,000 m3/d ADF and 40,000 m3/d PHF. Furthermore, the existing grit removal system is ineffective and needs complete replacement. Following commission of the new WWTP expansion, the existing headworks will be decommissioned.

8.7.4 Polishing Ponds and Rock FilterThe polishing ponds are currently used for the storage-treated effluent (not treatment). This function is retained in the plant expansion with the exception that some pond area is required for the necessary updates to the plant.

The rock filters were an experiment of the 2002 Plant Expansion to settle out algae that grew while the effluent was settling in the polishing ponds, but it does not appear effective at


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removing the algae. Unless the rock filter land is required for expansion of the WWTP, this study assumes they will be left as is.

8.7.5 Chlorine Contact Tank and BuildingThe Madaba WWTP has one CCT that lacks the serpent basin to achieve the necessary chlorine contact time and cannot be converted for effective disinfection treatment. The new chlorine contact tanks would be sized to provide 15-minute detention time at the design PHF of 40,000 m3/day.

The equipment in the existing chlorine storage and chlorine injection rooms is partly dismantled and has not been operated for years and will require complete replacement.

8.7.6 Effluent Storage PondThe existing irrigation (effluent storage) pond is the old polishing pond.

8.7.7 Sludge Gravity Thickener TanksEach of the two existing sludge gravity thickeners has a diameter of 9 m with a volume of 271 m3, including the conical-shaped bottom. Total available volume for sludge thickening is, therefore, 542 m3. Opportunities for reusing these structures include:

Septage thickening

Digested sludge storage

8.7.8 Drying BedsThe existing sludge drying beds are the underdrain type and will be maintained and upgraded, except for these beds in the way of process expansion of the WWTP.


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Section 10WWTP Expansion Implementation Program

This section provides a general outline for the program for the expansion of the Madaba WWTP, as identified by Task 4 of the USAID Jordan Water Infrastructure program.

9.1 IntroductionUpon official approval of the feasibility study findings by USAID and WAJ, the implementation basis of design and detailed design will start. This phase will include the preparation of a detailed engineering design for the construction of the wastewater treatment improvements based on the selected alternative in the feasibility study. The implementation program comprises the following main activities:

Preparation of Detailed Design Documents

Preparation of Tender Documents

Construction Contract Procurement

Construction and Construction Management

9.2 Preparation of Detailed Design and Tender DocumentsThe subtasks in this activity include:

Land Acquisition (if required)

Topographical Survey (completed for WWTP site)

Soil Investigations

Department of Antiquities Approval to Proceed

Ministry of The Environment – Approval to Proceed

Preparation of Basis of Design/Design Report

Detailed Design Development

Preparation of Bid Documents

Preparation of Engineer’s Cost Estimate

Preparation of Prequalification Documents

Project Summary Report

Formal reviews and approvals from USAID and WAJ will be obtained according to the timescale laid down in the contract. However, CDM Smith will simplify and expedite the

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approval process by involving WAJ engineers in all stages of the design process and in the intermediate review stages wherever possible.

9.2.1.1 Alternative Delivery OptionAs of writing this report, no alternative delivery (construction implementation) method was expressed by MWI/WAJ; therefore, this project will proceed following the conventional design, bid (tender), and build method according to International Federation of Consulting Engineers (FIDIC) Red Book guidelines.

9.2.2 Land Acquisition CDM Smith will assist WAJ in preparing documents and drawings required for land acquisition, if needed. Certified parcel drawings will define the land required for purchase. WAJ will have full responsibility for acquiring any land, including negotiations and services of counsel, that may be required. If land acquisition is required, it will need to be secured prior to moving forward with any other subtasks.

9.2.3 Topographical Survey and Soil InvestigationsThe extent of the topographical survey and soil investigation needed for the designs will be determined at an early stage of the implementation program. The soil investigation will include drilling boreholes or excavating test pits with depth and coverage equal to or exceeding the requirements of the relevant Jordanian code.

The soil investigation and topographical survey for the WWTP expansion is limited in scope to the existing site.

The topographical survey was completed and included in this report. The soil investigation will be incorporated into the Basis of Design Report to be available to the designers of the works. The soil investigation report will also be incorporated into the tender documents for the bidders’ and construction contractors’ consideration of subsurface conditions.

9.2.4 Department of Antiquities Approval to ProceedThe Madaba WWTP is not located near any important archeological sites. However, all construction activity will be carried out with due regard for Jordan’s Antiquities Law.

The Madaba offices of the Department of Antiquities are responsible for reviewing and approving proposals for construction projects in the area. If the proposed work will be carried out entirely within the existing site, the review process will be relatively simple. If other sites for the WWTP facilities are needed, the Department of Antiquities will need to review the potential for disturbance of archeological artifacts. The following steps are anticipated:

CDM Smith/WAJ will submit the scope of work and general details of the proposals to the Madaba Office of the Department of Antiquities. The details will include an outline of the recommended options, location maps, and expected duration of construction.

The Department of Antiquities will access the risks to antiquities from the construction, make recommendations, and define special conditions to be included in the contract.

Department of Antiquities approval must be obtained before tenders are invited.

At the construction stage, the contractor will need to submit security forms for all employees on the contract.


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9.2.5 Ministry of the Environment Approval to ProceedAll construction activities will be carried out with due regard to the Environmental Protection Laws of Jordan and, in particular, Law No. 52/2006 and Law No 6 of 2017. The Ministry of the Environment (MoE) is responsible for assessing the environmental impact of construction and approving the proposals. If the proposed work will be carried out entirely within the existing site, the review process will be relatively simple. This will simplify the review process. If other sites for the WWTP facilities are needed, the MoE will need to review the potential for adverse environmental impacts and recommend additional mitigation measures. The following steps are anticipated:

WAJ/CDM Smith will submit the Environmental Scoping Statement for the project, together with the scope of work and general details of the proposals. The details will include an outline of the recommended options, location maps, and expected duration of construction.

The Environmental Assessment Committee of the MoE will review the documents and either approve the proposals or make comments and recommendations that will need to be addressed.

The final stage is to submit the Environmental Assessment Report for the project to the MoE for approval of the proposed works.

9.2.6 Basis of Design ReportThe Basis of Design Report will consist of a number of technical memoranda giving an overview of particular aspects of the design (e.g., detailed design criteria, flows and loads, discussion and selection of process stages, detailed process design). The compiled Basis of Design Report will be reviewed by a Technical Review Committee independent of the USAID Jordan Water Infrastructure design team. The Technical Review Committee will rigorously examine and test all aspects of the Basis of Design to ensure compliance with Jordanian, CDM Smith, and industry best practices and standards.

9.2.7 Detailed Design DevelopmentAll designs will comply with Jordanian, CDM Smith, and industry standards and best practices. Multidisciplinary design teams will be created to ensure that each aspect of the design is developed with due regard to all engineering disciples. WAJ designers and operational engineers will be invited to participate in the design development.

Technical Committee Workshops will be held at the 30-percent and 60-percent completions to review the designs. The final design review will take place at the 90-percent completion.

The design will take into account all environmental factors and the need to maintain a high degree of treatment capability during the construction period.

A system of change control will be introduced to manage the evolution of drawing and records as the design process proceeds.

The design drawings and technical specifications will be provided with sufficient time to allow tenderers to fully understand the nature and scope of the work and to enable them to prepare accurate estimates of the costs.


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9.2.8 Preparation of Tender Documents – Design, Bid, and BuildThe tender documents will consist of four volumes:

1. Volume I: Tender Requirements, Contract Forms, and Conditions of Contract with BOQ

2. Volume II: Technical Specifications

3. Volume III: Drawings

4. Volume IV: Soil Investigation Report

9.2.8.1 Conditions of Contract The conditions of contract and BOQ form part of Volume I of the Tender Documents and define the duties, obligations, and rights of the parties during the execution of contract.

The governing conditions of contract will be the FIDIC standard for Civil Engineering Construction Contracts (Fédération Internationale des Ingénieurs-Conseils , 4th Edition).

If USAID will fund the project, then the 1987 version of the FIDIC Conditions of Contract will be used, or as required by USAID. If GoJ or other donors will fund the construction, then the 1999 version will be used, or as required by GoJ.

The Conditions of Contract will be in two parts, Part I will contain the General Conditions and Part II will contain Conditions of Particular Application to the proposed work. The Conditions of Particular Application will contain specific clauses required by WAJ and the GoJ. If USAID will fund the project, the Conditions of Particular Application will also contain specific clauses relative to source and origin, packaging and shipping, signage, and other USAID requirements.

The form of contract will be customized to account for the funding agency requirements. For example, a USAID-funded project will follow host country procurement procedures. Other donor funding or WAJ direct funding will require their own particular condition to be incorporated into the condition of contract and contract forms. Before Volume I of the tender documents can be prepared, CDM Smith will need guidance from USAID and/or WAJ as to the funding arrangements to be adopted.

9.2.8.2 Technical SpecificationsVolume II of the Tender Documents contains the Technical Specifications, both general and specific, for the works and materials necessary for the construction project. The specification will provide intelligence to the construction drawings and specify common standards, deviations accepted, materials accepted, and the required testing for materials. The specification will include references to construction standards and codes. Specifications will contain specific requirements for site development, architectural features, building mechanical, instrumentation and control, electrical, process mechanical, plumbing, structural, and any other disciplines required to complete the work.

9.2.8.3 DrawingsVolume III will contain all plans and drawings necessary for the construction of the works. A system of change control will be introduced to manage the drawing and records as the design process proceeds. Drawings will contain specific requirements for site development,


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architectural features, building mechanical, instrumentation and control, electrical, process mechanical, plumbing, structural, and any other disciplines required to complete the work.

9.2.8.4 Geotechnical ReportVolume IV will contain the soil investigations report, and test pit and boring logs for the tenderers’ information.

9.2.9 Engineer’s Cost EstimatesDetailed bills of quantities will be prepared from the drawings and specifications and will form part of Volume I, the Tender Requirements. These bills of quantities will be used to prepare the Engineer’s Cost Estimate, which will be confidential to the CDM Smith project managers, USAID, and WAJ.

Variations between the Engineer’s Cost Estimate and earlier estimates will be provided during the feasibility study design. The cost estimates are prepared according to the Association for the Advancement of Cost Estimating (AACE) International Recommended Practice No. 18R-97. The feasibility study is classified as a Class 4 estimate with an expected accuracy range low of negative-30 percent to high of plus-50 percent.

9.2.10 Prequalification DocumentsThe prequalification documents will be prepared before the end of the detailed design process. The prequalification and tendering procedure will depend on funding agency requirement. For example, USAID-funded projects will utilize Host Country Contract Procurement procedures. WAJ direct funding procurement will use prequalified Class A contractors.

9.2.11 Project Summary ReportThe project summary report will be prepared at the end of the detail design and tender preparation stage. It will detail the background to the project and describe how the project has developed from inception to preparation of the final design and tender documents. Technical and financial information will be presented in sufficient detail to ensure that the proposals can be independently assessed. The environmental impacts of the project will be presented together with the estimated cost of the works.

9.3 Project ScheduleTable 10-1 is the expansion of Madaba WWTP detailed design and tender document preparation schedule from the updated task work plan.

Table 10-1 Expansion of Madaba WWTP Work Plan

Task Name Start Finish Comment

Feasibility Study:Draft Feasibility Study Report submission NA 30 June 2020USAID/MWI/WAJ Review and Approval 30 June 2020 22 July 2020Final Feasibility Study Report 23 July 2020 August 2020Feasibility Study Workshop 9 July 2020 9 July 2020 Tentative date


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Task Name Start Finish Comment

Environmental Impact Assessment:Scoping Session and TOR August 2020 September 2020 Start after approval

of feasibility studyComprehensive EIA September 2019 December 2020Detailed Design and Preparation of Tender Documents:Conduct topo survey March 2019 March 2019 Plant site survey

completedConduct soil investigation July 2020 August 2020Draft Basis of Design Report (BODR) August 2020 October 2020BODR – USAID/MWI/WAJ Review and Approval October 2020 November 2020Final BODR December 2020 December202160-percent Design Stage December 2021 March 202190-percent Design Stage April 2021 June 2021Construction Tender Documents June 2021 July 2021USAID/MWI/WAJ Review and Approval July 2021 August 2021Final Madaba WWTP Construction Tender Documents

September 2021

Precontract Services September 2021 December 2021

9.4 Construction Contract Procurement and Construction Management

Construction contract procurement and construction management do not currently form part of the scope of work for Task 4 under USAID Jordan Water Infrastructure. The steps involved in the contract procurement are summarized below, assuming that USAID procedures are adopted and CDM Smith are retained for the Contract Procurement. CDM Smith will assist WAJ in preparing letters and reports necessary to obtain USAID’s formal approval on each stage of the tendering process in accordance with USAID and GoJ regulations.

9.4.1 Prequalification of ContractorsInvitations and advertisements of the proposed works will be prepared to bring the details of the proposed project to the attention of construction contractors. A prequalification questionnaire will be prepared in accordance with USAID and WAJ requirements and guidelines.

The prequalification applications will be evaluated by CDM Smith, WAJ, and USAID. Queries will be resolved with applicants and the results and recommendation of the prequalification process will be presented.

9.4.2 Precontract Services Site visits and pre-bid meetings will be arranged for prequalified contractors in coordination with WAJ and USAID. The arrangements include scheduling and participating in meetings, facilitating meetings, and providing explanations and details of the project to bidders. Concerns and issues that need special attention will be highlighted.


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Responses to questions and queries from bidders about the tender documents will be recorded, and any addenda needed to modify the contract documents in response to these questions and queries will be made in consultation with WAJ and USAID.

9.4.3 Evaluation of Bids and Award of ContractBids will be evaluated according to the criteria laid down in the contract. A draft tender evaluation report will be prepared for review by WAJ and USAID, after which the final tender evaluation report will be prepared.

Copies of the contract documents will be prepared for signing and an inauguration ceremony will be organized.

9.4.4 Construction It is estimated that the construction duration will be 30 months from the date of the signing of the contract. The construction phase will terminate with plant commissioning, acceptance, and turnover to WAJ. Acceptance and/or beneficial occupancy will start the defects liability period.

9.4.5 Commissioning The contractor is responsible for commissioning and wet testing all components of the constructed facilities and is responsible for operation and maintenance of the facilities for a period of one year after the signing of the certificate of completion. The cost of the operations and maintenance will be included in the contractor’s construction costs for the works.

END OF REPORT

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