MSIG Volume IV - Sewage Treatment Plant

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Table of Contents Page

Section 1 Introduction and General Planning Requirements 1.1 Purpose of This Volume 3 1.2 Who Should Use This Volume 3 1.3 Related Reference Material 3 1.4 General Planning and Design Approval Requirements 4 1.5 Guidelines for Design Calculations 5 1.6 Guidelines for Drawings 7

Table 1.1 Recommended Population Equivalent 6 Figure 1.1 Typical Hydraulic Profile 9 Figure 1.2 Typical Process and Installation Diagram 10 Figure 1.3 Typical Process Flow Diagram 11 Figure 1.4 Typical Mass Balance Diagram 12 Figure 1.5 Typical Electrical Single Line Diagram 12 Section 2 Design Overview 2.1 Treatment Plant Classification 15 2.1.1 Classification by Biological Treatment 15 Processes 2.1.2 ClassificationbyTreatmentPlantCapacity 16 2.2 Treatment System Selection / Design 16 2.2.1 General Selection Considerations 16 2.2.2 Design Stages 20 2.2.3 Detailed Design Criteria 20 2.3 Safety and Health Principles 23 2.3.1 General Safety 23 2.3.2 Structural Safety 24 2.3.3 Equipment and Electrical Safety 25

Table 2.1 Classification by Treatment Plant Capacity 16

Section 3 Sewage Characteristics and Effluent Discharge Requirements 3.1 Introduction 29 3.2 EQA Effluent Standards 29 3.2.1 Purpose of Effluent Standards 29 3.2.2 Interpretation of EQA Effluent Standards 29

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3.3 Design Requirements to Achieve EQA Effluent Standards 30 3.3.1 Purpose of Design Requirements 30 3.3.2 Design Values 30 3.4 Sewage Pollutants Removal 31 3.4.1 Biochemical Oxygen Demand (BOD5) 31 3.4.2 Total Suspended Solid (TSS) 32 3.4.3 Chemical Oxygen Demand (COD) 32 3.4.4 Oil and Grease (O&G) 32 3.4.5 Nitrogenous Compound 33 3.4.6 Phosphorus Compound 33 3.5 Sludge Characteristics and Treatment Requirements 34

Table 3.1 Design Influent Values 30 Table 3.2 Design Effluent Values 31

Section 4 Requirements for Physical Design 4.1 Introduction 37 4.2 Treatment Plant Siting 37 4.2.1 Buffer Zones 37 4.2.2 Siting Criteria 39 4.2.3 Environmental Impact Assessment 39 4.2.4 Hazard and Operability Studies 40 4.3 Treatment Plant Sizing 40 4.3.1 Modular Units 40 4.3.2 Standby Units 40 4.3.3 Back-up Capacity 41 4.3.4 Design Flow 42 4.4 Land Area Requirements 42 4.4.1 Class 1 and 2 Plants 42 4.4.2 Mechanised Class 3 to 4 Plants 42 4.4.3 Aerated Lagoons and Stabilisation Ponds 43 4.4.4 Imperfect Sites 43 4.4.5 Reduced Land Areas for STPs 43

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4.5 Mechanical and Electrical Requirements 53 4.5.1 Mechanical Installation 53 4.5.2 Vibration 54 4.5.3 Noise 54 4.5.4 Safety Around Equipment 55 4.5.5 Motors, Controllers and Motor Starters 55 4.5.6 Power Supply Systems 57 4.5.7 Back-up Generator 58 4.5.8 Switchgear and Control Gear Assemblies 59 4.5.9 Control Cabinets 60 4.5.10 Control Requirements 62 4.5.11 Supervisory Control and Data Acquisition 64 Systems (SCADA) 4.5.12 Early Warning System (EWS) 65 4.5.13 Instrumentation 65 4.5.14 Cables and Cabling Installation 67 4.5.15 Earthing and Lightning Protection 68 4.5.16 General Purpose Power 69 4.5.17 Manuals, Drawings and Labelling 69 4.5.18 Hazardous Areas 70 4.6 Material Requirements for STP Structures and Installations 70 4.6.1 Concrete and Reinforcement 70 4.6.2 Steel 72 4.6.3 Fibre Reinforced Plastic (FRP) 74 4.6.4 Aluminium 76 4.6.5 HDPE (High Density Polyethylene) 77 Table 4.1 Modulation Requirements 40 Table 4.2 Land Area Requirements for Class 1 44 Table 4.3 Land Area Requirement for Class 2 45 Table 4.4 Land Area Requirements for 45 Table 4.5 Land Area Requirements for 46 Table 4.6 Required Land Area for Stabilisation Pond and Aerated 47 Lagoons

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Figure 4.1 STP Land Area Requirements for Planning Layout Approval 49 for New Development Figure 4.2 STP Land Area Requirements for Structure Plans 50 Figure 4.3 Guidelines For Buffer Zone 51 Figure 4.4 Plan View of Buffer Zone Requirements 52 Figure 4.5 Clear Working Space 57

Section 5 Requirements for Individual Treatment Processes 5.1 Introduction 81 5.2 Design of Primary Screens 84 5.2.1 Purpose of Primary Screens 84 5.2.2 Inlet Chamber 84 5.2.3 Design Requirements for Primary Screens 85 5.2.4 General Requirements 86 5.3 Design of Pump Stations 91 5.3.1 Purpose of Pump Stations 91 5.3.2 Design Requirements 91 5.3.3 General Requirements 95 5.4 Design of Secondary Screens 100 5.4.1 Purpose of Secondary Screens 100 5.4.2 Design Requirements 100 5.5 Design of Grit and Grease Chambers 101 5.5.1 Purposes of Grit and Grease Chambers 101 5.5.2 General Requirements 102 5.5.3 Design Criteria 103 5.6 Design of Balancing Tanks 105 5.6.1 Purposes of Balancing Tanks 105 5.6.2 Design Requirements 105 5.7 Design of Primary Sedimentation Stage 106 5.7.1 Purposes 106 5.7.2 Design Requirements 106 5.8 Design of Biological Treatment Stage 108 5.8.1 Introduction 108 5.8.2 Conventional Activated Sludge System (CAS) 109 5.8.3 Extended Aeration System (EA) 111 5.8.4 Rotating Biological Contactors (RBC) 114 5.8.5 Trickling Filter 116

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5.8.6 Sequencing Batch Reactors (SBR) System 117 5.8.7 Design Requirements for Hybrid Systems 120 5.8.8 Design for Nutrient Removal for Sensitive 120 Receiving Water 5.9 Design of Secondary Clarifiers 122 5.9.1 Purpose 122 5.9.2 Design Requirements 122 5.9.3 Multiple Hoppers 123 5.10 Disinfection 125 5.10.1 Design Requirements 126 5.11 Design of Flow Measurement Devices 130 5.11.1 Purpose of Flow Measuring Devices 135 5.11.2 Design Requirements for Flow Devices 135 5.12 Sludge Holding, Treatment and Disposal 136 5.12.1 Introduction 136 5.12.2 Sludge Strategy in General 137 5.12.3 Provision of Sludge Holding, Treatment and Disposal 138 5.12.4 Design Criteria 139 5.13 Tertiary Treatment 144 5.13.1 Introduction 144 5.13.2 Design Requirement 144

Table 5.1 Requirement for Inlet Chamber 84 Table 5.2 Provision of Primary Screens 85 Table 5.3 Design Parameters for Primary Screens 86 Table 5.4 Recommended Design Parameters for Inlet Pump Stations 99 Table 5.5 Provision Requirement of Secondary Screens 100 Table 5.6 Design Parameters for Secondary Screens 101 Table 5.7 Provision Requirement of Grit and Grease Removal System 103 Table 5.8 Design Parameters for Grit Chambers 103 Table 5.9 Design Parameters for Grease Chambers 104 Table 5.10 Design Parameters for Balancing Tanks 106 Table 5.11 Design Parameters for Primary Sedimentation 108 Table 5.12 Design Parameters for Conventional Activated Sludge 110 System Table 5.13 Design Parameters for Extended Aeration 111 Table 5.14 Design Parameters for RBC Plants 112

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Table 5.15 Design Parameters for Trickling Filter 117 Table 5.16 Design Requirements for SBR System 119 Table 5.17 Design Requirement for Biological Nutrient Removal 120 System Table 5.18 Design Parameters for Secondary Clarifiers 124 Table 5.19 Requirements for Disinfection Facility 126 Table 5.20 Design Guides for Disinfection with Ultra-Violet (UV) 130 Table 5.21 Design Guide for Disinfection with Hypochlorite 133 Table 5.22 Design Guide for Intermittent Disinfection 134 Table 5.23 Design Parameters for Flow Devices 135 Table 5.24 Sludge Generation Rates 136 Table 5.25 Design Parameters for Sludge Thickening 139 Table 5.26 Design Parameters for Aerobic and Anaerobic Digestion 140 Table 5.27 Recommended Design Parameters for Sludge Treatment 141 Figure 5.1 Typical Treatment Process Flow Chart 82 Figure 5.2 Typical Elements and Process Flow Diagram of a Sewage

Treatment Plant 83 Figure 5.3 Typical Drawing of Double Penstock 85 Figure 5.4 Quantities of Screenings Collected From Primary Screens 88 Figure 5.5 Typical drawing of screen chamber based on depth. 89 (<5m for different PE) Figure 5.6 Typical drawing of screen chamber based on depth. 90 (<5m for different PE) Figure 5.7 Typical Dimensions of Wet-well Submersible Pump Station 93 Figure 5.8 Typical Dimensions of Dry-well Submersible Pump Station 94 Figure 5.9 Typical details of wet-well pump station 97 Figure 5.10 Typical details of dry-well pump station 98 Figure 5.11 Fine Bubble Diffuser Air – Extended Aeration System 113 Figure 5.12 Oxidation Ditch Activated Sludge System 114 Figure 5.13 Deep Shaft Activated Sludge System 116 Figure 5.14 Rotating Biological Contactor (RBC) Systems 119 Figure 5.15 Typical Process Flow Diagram for Biological Nutrient 121 Removal System Figure 5.16 Schematic illustration of ultraviolet disinfection system 126 with stilling plate for flow conditioning and elongated weir for level control

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Figure5.17 Profileschematicoflampmodulesrelativetoinletand 127 outlet structure Figure 5.19 Chemical-feed system schematic 127 Figure 5.20 Sludge Treatment and Disposal Strategy 143 Figure 5.21 Typical Roof Details for Covered Sludge Drying Bed 146

Section 6 Requirements for Ancillary Facilities 6.1 Introduction 149 6.2 Water Supply and Wash Water 149 6.3 Mess Facilities and Ablutions 150 6.4 Roads and Access 152 6.5 Drainage 153 6.6 Fencing and Security 154 6.7 BeautificationZoneandLandscape 159 6.8 Stores and Workshops 159 6.9 Spares 159 6.10 Yard Lighting 161 6.11 Sampling Facilities 162 6.12 Auto Restart Facilities 162 6.13 Safety Facilities 163 6.14 Doors 163 6.15 Fire Hydrant 163 6.16 Power Supply 164 6.17 Internal Sanitation (Toilet) 164 6.18 Lifting Requirement 164 6.19 Ventilation 165 6.20 Process Water 168 6.21 Aesthetic 168 6.22 Close Turfing 168 6.23 StandardRoofingandrelatedrequirement 168 6.24 Painting 169

Table 6.1 Minimum Number of Recommended Water Stand 150 Pipe and Location Table 6.2 Spare Part 161 Table 6.3 Numbers of Unit and Location of Compound Lighting 161

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Table 6.4 Common ventilation rates 167

Table 6.5 Painting System Index – Colour Standards 170

Figure 6.1 Standard Details for Stand Pipe 151

Figure 6.2 Typical for Administration and Mess Facilities Building 152

Figure 6.3 Typical Details of Road Pavement 152

Figure 6.4 Typical Road Section of Site Road 152

Figure 6.5 Typical Drawing of Brickwall Fencing and Gate 155

Figure 6.6 Brickwall Fencing 156

Figure 6.7 Precast Fencing 157

Figure 6.8 Masonry Fencing 158

Figure 6.9 Typical Details of Compound Lighting 162

Figure 6.10 Typical Detail of Guard Rail 171

Figure 6.11 Typical Detail of Lifting Davit 172

Figure 6.12 Typical Detail of A-Frame Lifting Facilities 172

Section 7 Special Requirements

7.1 Temporary Treatment Plants 175

7.1.1 Definition 175

7.1.2 Category 1: Temporary Treatment Plant for 175 Upgrading of Facilities

7.1.3 Category 2: Temporary Plants for New Housing 176 Development

7.2 Treatment Plants Located Within Buildings 179

7.2.1 Introduction 172

7.2.2 SpecificGuidelinesandRequirements 180

7.3 Fully Enclosed Treatment Plant 181


7.3.2 General Requirements 185

7.3.3 SpecificRequirements 186

7.4 Covered and Buried Treatment Plants 194


7.4.2 General 194

7.4.3 SpecificRequirements for Covered or Buried 194 Plants under 5,000 PE or Less

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7.5 Guidelines for Homestead Developments 197 7.5.1 Single Developments up to 30 Units or 150 197 PE in Total 7.5.2 Single Developments Over 30 Units in Total 197

with Average Housing Density Greater Than Five Units per Hectare 7.5.3 Single Developments Over 30 Units in Total with 197 Average Housing Density Less Than Five Units per Hectare 7.6 Non-Compliance with Standards 198 7.6.1 Introduction 198 7.6.2 Types of Incident’s that Can Cause Treatment 198 Plant Failure 7.7 Energy Saving 201 7.8 Recycle and Reuse 201

Section 8 Package Sewage Treatment Plant 8.1 Definition 205 8.2 Land Area Requirement 205 8.3 Design Requirement 206 8.4 Components of Package Sewage Treatment Plant 206 8.4.1 Layout, Piping and Arrangement of Prefabricated 206 Biological Treatment System 8.4.2 Prefabricated Tanks 206 8.4.3 Process Treatment Units/Components 207 8.5 Appurtenances 208 8.5.1 Piping system 208 8.5.2 Pumping System 209 8.5.3 Diffuser 210 8.5.4 Flow Distribution Chamber 210 8.5.5 Manhole Cover/Inspection Chamber Cover 210 8.5.6 Anchor System Loading 211 8.5.7 Landscaping 211 8.5.8 Odour Treatment 211 8.5.9 Ancillary Facilities 212 8.6 Marking and Labelling 212

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Table 8.1 Minimum Design Life Span of Package Sewage 206 Treatment Plant Components

Table 8.2 Recommended Number of Tanks and Effective Volume 207 Consideration for Various Unit Processes

Table 8.3 Technical Requirements of Pumping System 209

Table 8.4 Technical Requirements of Manhole Cover 210

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Appendices

Appendix A Table Table A1 Contaminants of Concern in Sewage Treatment 216 Table A2 Typical Composition of Untreated Domestic Sewage 217 Table A3 Major Biological Treatment Processes Used for Sewage 218 Treatment Table A4 Interim National River Water Quality Standards for Malaysia 220 Table A5 River Clarification 221 Table A6 The Occupational Safety and Health Act 514, 1994 - Brief 222

Summary of Contents Table A7 Permissible limits for potentially toxic elements in soil 223 Table A8 Options for disposal of Sludge and reuse of bio-solids 224

Appendix B References Malaysian Standards 227 British Standard 228 European Standard 229 ASTM Standard 231 AS Standard 232 Other Reference Materials 232 Other Guidelines in This Set 232

Appendix C Supervisory Control and Data Acquisition System (SCADA) C-1 Introduction: Overview 237 C-2 Purpose 238 C-3 General Requirements 238 C-4 Architecture 238 C-5 SCADA Requirement 239 C-6 Operator Interface 240 C-7 Database 241 C-8 Alarm/Event Management 241 C-9 Historian 243 C-10 Graphical Trending 243 C-11 Report Format 244 C-12 Security 244 C-13 Scripting 245

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C-14 Interfaces 245

C-15 Distributed Server Architecture 245

C-16 Web Server 245

C-17 Digital Video Monitoring 246

C-18 Integrated Maintenance Management 246

C-19 Application Report 247

C-20 Application Programming Interface 247

C-21 User Documentation 248

C-22 SpecificationsandSizing 248

Appendix D Duty and Standby Requirements

Table D.1 Duty and Standby Requirements for Activated Sludge 268 Systems (Utilising Diffused Aeration)

Table D.2 Duty and Standby Requirements for Activated Sludge 269 Systems (Utilising Mechanical Surface Aerator)

Table D.3 Duty and Standby Requirements for Rotating Biological 270 Contactor Systems

Table D.4 Duty and Standby Requirements for Trickling Filter Systems 271

Appendix E Glossary of Abbreviations

Glossary of Abbreviations 275

Section 1

Introduction and GeneralPlanning Requirements

Volume 4

Introduction and General Planning Requirements

Malaysian SewerageIndustry Guidelines

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Volume 4 3Sewage Treatment Plants

1.1 Purpose of This Volume

This Volume sets out the requirements of the National Water Services Commission (SPAN) (referred to as the Commission in this document) for the planning, design and construction of sewage treatment plants. This Volume contains the following:

a) An overview of considerations and criteria for sewage treatment plant design.

b) Effluent discharge standards requirements and the capacity of different sewage treatment processes to meet these standards.

c) Requirements for the siting and sizing of sewage treatment plants.

d) Requirements for each stage of sewage treatment.e) Minimum requirements for facilities ancillary to a sewage treatment

plant.f) Other special requirements for temporary treatment plants, treatment

plants within buildings, homestead developments and exemptions for non-compliance with standards.

g) Requirements of sludge treatment process and disposal.

The owner must comply with the requirements set out in this volume when submitting an application for approval to the Commissioner.

This volume does not cover any aspect other than Sewage Treatment Plant requirements. All internal plumbing approvals need to be approved by Local Authorities.

1.2 Who Should Use This Volume

This Volume is primarily for owners, developers, consulting engineers and Public Authorities whose developments include sewage treatment plants.

1.3 Related Reference Material

This Volume does not cover all aspects of design and construction of sewage treatment plants. Where information is not covered in this volume, the designer shall follow the requirements given in MS 1228.

However, the information in this Volume shall take precedence over MS 1228 where similar aspects are covered in these documents or where there is conflicting information between the two documents.

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The procedures for certification of sewerage services are given in the Malaysia, Volume 2 Sewerage Works Procedures.

All Standards references adopted during this revision exercise are compiled and given in Appendix B.

1.4 General Planning and Design Approval Requirements

The application procedures for sewage treatment plants approval shall follow the requirements given in MSIG Volume 2. In general, the application for approval of a treatment plant shall include:

a) Sufficient land area for the sewage treatment plants plus additional area to allow for extensions to the plant, where necessary.

b) Land of suitable configuration shall be provided.c) Sufficient buffer zones.d) The location of a sewage treatment plant in relation to a particular

catchment area. The plant unit processes shall be located at an elevation which is not subject to flooding/wave action, or shall otherwise be adequately protected against all flooding/wave action.

e) Sufficient topographic features shall be included to indicate its location in relation to streams and the point of discharge of the treated effluent.

f) Schematic flow diagrams showing utility systems serving the plant processes and the flow through various plant units.

g) Pipeworks, including any arrangements for bypass from individual units. The direction of flow and the content in the pipes shall also be clearly and permanently painted onto all exposed piping works.

h) Hydraulic profiles showing the flow of sewage, supernatant liquor, and sludge.

i) Location, dimensions and elevations of all existing and proposed plant facilities.

j) Capacity of the effluent receiving drain/water course shall be able to cater for additional discharge flow from the treatment plant.

k) Consideration for odour and noise mitigation and control through good facility design, effective operation, containment, collection and treatment.

l) Point of discharge of treated effluent (effluent outfall) and elevations



of high and low water levels of the receiving watercourse to which the plant effluent is to be discharged.

m) Type, size, features, and operating capacity of all pumps, blowers, motors and other mechanical devices together with manufacturer catalogues.

n) Minimum, average and maximum hydraulic flows, velocities and top water level in profiles.

o) Accessibility, landscaping and fencing.p) Flow measurement facilities.q) Materials, dimensions and specifications.r) Ground conditions including levels, type, groundwater level and

safe bearing pressure of foundation.s) Details of foundation and other structural design. Slope protection

works are required, where applicable.t) All other components of the sewage treatment plant.u) A technical report, which covers the ‘whole life cost’ evaluation

of the plant.v) Process and instrumentation diagram.w) Mass balance calculation

x) Clean and legible detailed drawings in standard formaty) Operation and Maintenance needs of the plant to be addressed

at the early planning stage.z) Where required, an EA or EIA report is needed to identify,

predict, evaluate and communicate information concerning the adverse and beneficial impacts of the proposed treatment plant.

aa) HAZOP requirement is necessary to identify the safety and operability deficiencies in the design and operation of the treatment plant.

1.5 Guidelines for Design Calculations

Design calculation for all unit processes shall be in sequence starting from inlet works to biological treatments and sludge treatments as shown in Figure 5.1. The calculation shall include:

a) Sizing of each unit processes and all mechanical equipment involved.

b) Mass balance for overall system and each unit process.c) Influent values.

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d) Design influent and effluent values in compliance with Section 3.3.2.

e) Treatment plant shall be designed based on design flow.f) Hydraulic profile across the treatment units to be indicated onto

to the drawings.g) Each unit process must comply with the design parameters set

in Section 5.h) Calculation of PE to be based on Table 1.1.

Table 1.1 Recommended Population Equivalent

Type of Premises/ Establishment Population Equivalent (Recommended))

Residential 5 per house

Commercial:

Includes offices, shopping complex, entertainment/ recreational centres, restaurants, cafeteria, theatres

3 per 100 m2 gross area

Schools/ Educational Institutions:

- Day schools/ Institutions

- Fully residential

- Partial residential

0.2 per student

1 per student

0.2 per non-residential student

1 per residential student

Hospitals 4 per bed

Hotels with dining and laundry facilities 4 per room

Factories, excluding process water 0.3 per staff

Market (wet type) 3 per stall

Market (dry type) 1 per stall

Petrol kiosks/Service stations 15 per toilet

Bus terminal 4 per bus bay

Taxi terminal 4 per taxi bay(Ref: Malaysian Standard 1228)



Table 1.1 - Recommended Population Equivalent (Cont)

Type of Premises/ Establishment Population Equivalent(Recommended)

Mosque/ Church/ Temple 0.2 per person

Stadium 0.2 per person

Swimming pool/ Sports complex 0.5 per person

Public toilet 15 per toilet

Airport 0.2 per passenger

0.3 per employee

Laundry 10 per machine

Prison 1 per person

Golf course 20 per hole(Ref: Malaysian Standard 1228)

1.6 Guidelines for Drawings

All drawings shall be of standard format and orientation. The drawings required include:

a) Overall development plan showing the whole sewerage system and plant location.

b) Site layout plan showing the arrangement of the plant, buffer zone, internal set backs and all neighbouring developments.

c) Site layout plans showing all the process units, main pipe runs, electrical conduit corridors, site services (water, drains, lighting, other services), roads and paving, landscaping, buildings, fencing and finished level contours (or spot levels). The set out and overall dimensions of the plant shall also be shown.

d) Site elevations of the plant with at least one section through the plant in each direction. These sections shall extend at least 30 m from the plant boundary and include an indication of the surrounding development (in block form only).

e) Process and instrumentation diagram (P&ID) showing all tanks, pipes, channels, valves, mechanical equipment, instrumentation and control loops. The P&ID can also act as a summary of the design. It provides key details of each piece of equipment, tank, piping, valves and instruments.

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f) Hydraulic profile showing all hydraulic pathways through the plant including bypasses. Information to be shown includes pipe sizes, invert levels, flow velocities, tank coping level, top water level and freeboard. Top water level and velocities at minimum flow, average flow and peak flow under design load must be clearly indicated.

g) Schematic flow diagrams and mass balances showing flow through all process units in the plant.

h) General arrangement drawings of each unit process. These drawings shall be in sufficient details to clearly describe the shape, size and function of each unit. The drawings shall show the structure of the unit, piping, valves and fittings, instrumentation, mechanical and electrical equipment, buildings, handrails, stairs, ladders, step irons, site services such as water and lighting, adjoining paving, roadworks, fencing, drainage, etc. Drawings of all items should show the elevations, plan view and sectional view (horizontally and vertically), where applicable.

i) Details are required of any object that would affect the operation or maintenance of the plant that is not covered by a standard drawing.

j) Required to use standard symbols and legend formats for all drawings.




Sewage Treatment Plants Volume 4 Page 7

Figure 1.1 – Typical Hydraulic Profile

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Figure 1.1 Typical Hydraulic Profile

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Figure 1.2 Typical Process and Instrumentation Diagram




Sewage Treatment Plants Volume 4 9

Figure 1.3 Typical Process Flow Diagram

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Figure 1.3 Typical Process Flow Diagram

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Figure 1.4 Typical Mass Balance Diagram


10 Volume 4 Malaysian Sewerage Industry Guidelines

Figure 1.4 – Typical Mass Balance Diagram

BOD = 10% SS to be removed

BOD =

Qw OVERFLOW =

For Dewatering to 25% Dry SolidSludge to be pumped to Sand Drying Bed

SS = 4%DS =

SS = BOD =

Q = Qi + Qr + Qw

Qr, Xr

BOD = Qr = X Qi =

SS =

SS = BOD =

Qi =

SS =

MLSS =

AERATION TANK

PHYSICAL TREATMENT

1) PRIMARY SCREEN2) SECONDARY SCREEN

BOD =

SLUDGE THICKENER

SS = BOD = Qw =

SS =

1%DS =

Qw =

Qe =

OUTLET

SS = BOD =

OVERFLOW SS CONC =

SECONDARY CLARIFIER

BOD =

Qr + Qw =

INFLOW PARTICULARSQ =

AEROBIC DIGESTED

SLUDGE HOLDING TANK

Figure 1.5 - Typical Electrical Single Line Diagram

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U S IN G 4C x 16m m P V C /S W A P V C A R M . C AB LE

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Figure 1.5 Typical Electrical Single Line Diagram



Figure 1.4 – Typical Mass Balance Diagram

BOD = 10% SS to be removed

BOD =

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PHYSICAL TREATMENT

1) PRIMARY SCREEN2) SECONDARY SCREEN

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Figure 1.5 - Typical Electrical Single Line Diagram

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Section 2

Design Overview

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Design Overview


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Design Overview


2.1 Treatment Plant Classification

2.1.1 Classification by Biological Treatment Processes

The microorganisms in sewage treatment can be grown in a form of fixed film, suspension or a combination of both. Hence, biological treatment processes for sewage treatment works can be classified under one of the following headings:

a) Attached Growth Processes

b) Suspended Growth Processes

c) Combined Processes (Hybrid)

2.1.1.1 Attached Growth Processes

In an attached growth process, the active microorganisms grow and attach on the mobile or immobile medium (rock or plastic) that is in contact with sewage. The surface area of the biomass is used as the practical measure of the total organism activity. Types of attached growth processes include:

a) Trickling Filter (TF)

b) Rotating Biological Contactor (RBC)

c) Submerged Biological Contactor (SBC)

d) Fluidised Bed

e) Packed Bed Reactor

2.1.1.2 Suspended Growth Processes

In a suspended growth process, active microorganisms remain in suspension in the sewage and their concentration is usually related to mixed liquor suspended solid (MLSS) or mixed liquor volatile suspended solid (MLVSS). This system was developed as a result of studies that showed that if sewage is aerated over a long period of time, the organics in the sewage are removed by the active microorganisms grow during the process.

Types of suspended growth processes include:

a) Waste Stabilisation Pond System

b) Aerated Lagoon

c) Conventional Activated Sludge (CAS)

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Design Overview


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d) Extended Aeration (EA) e) Oxidation Ditch (OD) f) Deep Shaft (DS) g) Sequencing Batch Reactor (SBR) h) Any other treatment processes which comply with the design

principles of one of the above processes.

2.1.1.3 Hybrid Processes - Attached Growth with Suspended Growth

Recent developments in sewage treatment technology include the combination of various attached growth and suspended growth processes to obtain the best performance and most economical treatment of sewage.

One of the advantages of Hybrid Process is the process combines the stability and resistance to shock loads of an attached growth process and the capability to produce high-quality effluent of an suspended growth system.

Hybrid processes can be used to upgrade existing attached growth and suspended growth process, in particularly plants with high suspended solids in the final effluent due to poor solids settlement in the final clarifier.

2.1.2 Classification by Treatment Plant Capacity

Sewage treatment plants are also classified in accordance to the design capacity in terms of population equivalent (PE). Table 2.2 tabulates 4 clarifications to be adopted.

Table 2.1 - Classification by Treatment Plant Capacity

Classification PEClass 1 ≤1000Class 2 1001 – 5000Class 3 5001 – 20000Class 4 > 20000

2.2 Treatment System Selection / Design

2.2.1 General Selection Considerations

The following factors must be considered when selecting a sewage treatment process:

Design Overview


Process The applicability of a process is evaluated on the basis of past experience, data from full-scale plants and pilot data from treatment plant studies. If new or unusual conditions are encountered, pilot-plant studies are necessary.

Flow Range The selected process should be matched to the expected flow range.

Flow Variation Most unit operation and processes work best with a constant flow rate, although some variation can be tolerated. If the flow variation is too great, flow equalisation may be necessary.

Influent Sewage The characteristics of the influent will affect the types of processes to be used and the requirements for their proper operation.

Inhibiting Constituents

Identify the constituents present that may be inhibitory, and the conditions they are in.

Climatic Constraints

Temperature affects the rate of reaction of most treatment processes.

Reaction Kinetics and Reactor Selection

Reactor sizing is based on the governing reaction kinetics. Data for kinetic expressions are usually derived from experience, literature and results of pilot-plant studies.

Performance Performance is usually measured in terms of effluent quality, which must be consistent with the given effluent discharge requirements.

Treatment Residuals The types and amounts of solid, liquid and gaseous residuals produced must be known or estimated.

Sludge Handling Constraints

In many cases, a treatment method should be selected only after the sludge processing and handling options have been explored.

Environmental Constraints

Nutrient requirements must be considered for biological treatment processes. Environmental factors, such as the prevailing winds and wind directions, may restrict the use of certain processes, especially where odours may be produced.

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Design Overview


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Chemical Requirements

Classify chemicals and amounts that must be committed for a long period of time for the successful operation of the unit operation or process.

Energy Requirements

The energy requirements, as well as probable future energy costs, must be known if cost-effective treatment systems are to be designed.

Other Resource Requirements

Identify additional resources that must be committed to the successful implementation of the proposed treatment system using the unit operation or process in question.

Reliability Consider the long-term record of the reliability of the unit operation or process under consideration.

Complexity Evaluate the complexity of the process to operate under routine conditions and under emergency conditions such as shock loadings, as well as the level of training the operator must have to operate the process.

Ancillary Processes Identify the required support process and the effect on the effluent quality, especially when they become inoperative.

Compatibility The unit operation or process shall be used successfully with existing facilities, plant expansion and modifications.

Odour and Noise Odour and noise pollution should be minimised to the lowest possible level.

Aesthetics The selected treatment process should aesthetically suit the development site.

Safety and Operability

The chosen treatment process shall be designed with utmost care to facilitate safe operations at all times as well as to incorporate safety features for the protection of operators. See Section 2.3.

Design Overview


Land Requirements A more compact plant component may perform equally well to a component taking up more land and thus would be preferential, provided there was no significant component cost differences.

Ease of Operation and Maintenance

This will dictate whether plant has to be continuously or intermittently operated and whether skilled or relatively unskilled personnel would be required to carry out the operations and maintenance works.

Modulation Modulation refers to the ability of process units to be expanded in tandem with flow increases. Modulation minimises the time that the plant sits idle before utilisation and lowers initial capital outlay.

Standardisation This brings about economics on design effort, material procurement, quality checks, spares and maintenance costs.

Adaptability Adaptability refers to the ability to readily upgrade or uprate the performance of a treatment plant with relatively minor extra works.

Sludge Management This is an important aspect that needs careful evaluation. Treatment systems that minimise waste sludge production, and which produce a relatively stable sludge should be given preference. See Section 5.12

Overall Cost This will include considerations of capital, operation and maintenance costs. Spare parts costs related to maintenance can be hidden costs that also need consideration, particularly where there may be long time delays obtaining parts or specialist inputs are required.

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2.2.2 Design Stages

The design of a sewage treatment plant comprises the following stages:

Process Design In this stage, a suitable sequence of processes are selected to meet stipulated final effluent requirements for the plant concerned.

Functional Design In this stage, calculation of capacities required are conducted for all major units, channels, pumps and pipework and also definition of control requirements. These include designs for hydraulic, organic and solid loadings.

Detailed Design In this stage, structural design of units and channels, detailing of pipelines, fittings and control valves, and selection of mechanical, electrical and control equipment are conducted.

2.2.3 Detailed Design Criteria

For the following characteristics and requirements of a treatment plant, the designer needs to consider a number of detailed design criteria:

a) Biochemical characteristics

b) Physical characteristics

c) Hydraulic characteristics

d) Mechanical & engineering requirements

e) Structural requirements

f) Constructional characteristics

2.2.3.1 Biochemical Characteristics

These involve the consideration of the following parameters:

a) Chemical characteristics of sewage

b) Good activity between microorganisms and waste materials

c) Optimal substrate concentration

d) Operational stability (half-life and activity decay profile)

e) Availability of suitable nutrients

f) Maintenance of favourable environment

g) Effect of filamentous growth & sludge bulking

Design Overview


h) Effect of dissolved oxygeni) Productivity in lifetime usagej) Minimum and maximum residence timesk) By-product formationl) pH and temperature sensitivitym) Storage stabilityn) Reactor effluent quality-composition, colour, odour, etc.o) Sludge production and frequency of desludgingp) Effective material balance analysisq) Development of biochemical kinetic coefficient through pilot

plants

2.2.3.2 Physical Characteristics

These involve the examination of:

a) Particle shape and size distributionb) Dry and wet bulk densityc) Swelling behaviourd) Compressibilitye) Cohesion and particle attritionf) Settlementg) Floc formationh) Settling velocity and sedimentation

2.2.3.3 Hydraulic Characteristics


a) Hydraulic velocities in all unit processesb) Mode of flow, upflow versus downflowc) Axial dispersion and channellingd) Pressure drop and head loss through plante) Residence time distribution and retention timef) Stratificationg) Length to width ratioh) Minimum velocity for onset of fluidisation

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Design Overview


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i) Weir loadings

j) Overflow rate

2.2.3.4 Construction Characteristics


a) Ground conditions and soil characteristics

b) Land availability

c) Type of plant depending on density and type of community to be served

d) Distance to nearest habitation

e) Delivery and construction time

f) Recommended maintenance requirements

g) Start-up time and procedure

h) Noise levels

i) Technical capability to construct, operate and maintain the system

2.2.3.5 Structural Requirements

a) Wall, slab, beams, columns and structure for sewage treatment plant shall be in reinforced concrete.

b) Wall shall have minimum thickness of 225 mm.

c) Special foundation shall be provided where necessary.

d) Proper jointing to prevent breakage and leakage.

e) Water retaining and slope protection where applicable.

2.2.3.6 Mechanical & Electrical Requirementsa) The design shall simplify the equipment required, control system,

maintenance and operational procedures, while fulfilling the intended performance and standard of service.

b) Equipment selected shall be from manufacturers (and models) approved by the Commission.

c) Equipment, cable and cabling design and installation shall follow IEE and TNB requirements.

d) Foundations shall be structurally designed and anchored to withstand all loads imposed by the equipment. Reinforced concrete foundations are preferred.

Design Overview


e) Joints shall be provided in all piping to allow removal of equipment, meters, valves and other special items without causing dismantling of the pipeline.

f) Equipment shall be equipped with safety protection (i.e. emergency stop button, warning signage & etc.). See Section 4.5.

g) Pipeworks shall be neatly arranged and properly supported.h) Appropriate type of control system provided for the treatment

plant. See Section 4.5.i) Construction materials to be protected against corrosion due to

high humidity.j) Earthing and protection against lightning.k) System manuals, plant function diagrams, electrical system,

electrical circuit and instrument loop diagrams shall be provided before the plant is pre-commissioned.

l) Detailed and shop drawing for equipment, instrumentation and cable & cabling shall be provided.

2.3 Safety and Health Principles

Throughout the design, construction, commissioning, operation and maintenance stages of a project, the following safety principles shall apply:

2.3.1 General Safety

a) Malaysian Safety and Health legislations, standards and procedures under Occupational Safety and Health Act (OSHA) 1994, Factories and Machinery Act 1967 and etc. shall be followed.

b) Workforce, contractors, visitors and the public shall be safeguarded against hazards, risk of serious injury and disease.

c) Adequate training shall be made available for the use of all related equipment.

d) Appropriate training for end users to be identified and stipulated in construction and procurement documents.

e) Appropriate responsibilities to be assigned throughout each stage of a project.

f) Safety consciousness to be promoted by effective internal communication, signs and media.

g) Safety performance shall be easily audited during operation and maintenance.

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h) All accidents or potential serious incidents to be reported and investigated.

i) Risk assessment to be undertaken at design of projects and selection stage of procurement.

j) Safety information and operating documents to be provided by suppliers.

k) Emergency contact list, showing telephone numbers of key personnel and emergency services during office hours and out of office hours, to be circulated to all parties involved in a project.

l) Plant (certain sized) should be provided with Emergency Response Plan (ERP)

m) All treatment plants, installation and construction sites, shall be provided with perimeter fencing adequate to protect the public from entry. All fencing shall be securely fixed and inspected.

n) All treatment plants, installations and construction sites shall have adequate warning signs at or near the perimeter.

o) Access to construction sites shall be controlled to prevent unauthorised access.

2.3.2 Structural Safety

a) Safe access to all working areas to be provided.

b) Routine requirement to enter confined spaces to be eliminated, where practicable.

c) Any confined space requiring routine person entry, which contains sewage, sludge or other foul water, to be ventilated.

d) Concrete slabs over wet wells, tanks and chambers shall have double steel reinforcing.

e) Lifting eyes and bolts for slabs to be stainless steel or any other durable and non-corrosive material.

f) Protection against falling (i.e. handrail, kick plate and toe plate) to be provided.

g) Within plants and installations, all wells, sumps, channels, chambers, tanks, etc. containing any liquid shall be covered, walled or railed.

h) Major hazards to be identified and posted on site.

i) Protection and counter measures against spillage of dangerous chemicals to be provided.

Design Overview


j) Permanent staircase shall be provided at inlet sumps, inlet wells, inlet chambers and dry-wells. Steps and riser shall follow UBBL Standard.

k) Adequate lifting facility shall be provided for heavy equipment, which requires maintenance work.

l) Blower room shall not share common wall and foundation with the control and genset room

2.3.3 Equipment and Electrical Safety

a) Electrical equipment and controls to be protected from unauthorised access.

b) Individual electrical drives to be capable of being isolated and locked off.

c) Electrical motors should be rated as continuous run.

d) Junction boxes for submersible pumps and float controls shall be above floor level outside the wet-well.

e) All electrical equipment in sumps, wet-wells, inlet channels, inlet chambers, sited below coping level to be explosion proof.

f) Lighting, appropriate to the needs of the end user, to be provided in working areas.

g) Registration of electrical / motorised equipment with Department of Safety and Health (DOSH).

h) Emergency stop button / isolator shall be provided for each equipment.

i) Power driven machinery to be guarded.

j) All equipment to be regularly checked and prominently marked accordingly

Section 3

Sewage Characteristics and Effluent Discharge

Requirements

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Sewage Characteristics and Effluent Discharge Requirements


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3.1 Introduction

The Environmental Quality Act (EQA) 1974 specifies two standards for effluent discharge: Standard A for discharge upstream of any raw water intake, and Standard B for discharge downstream of any raw water intake.

The current Third Schedule of the Environmental Quality Act 1974, under the Environmental Quality (Sewage and Industrial Effluents) Regulations, 1979, regulations 8 (1), 8 (2) and 8 (3) has been revisited and the Department of Environment has proposed 8th Schedule for the Act which stipulate effluent discharge limits for parameters specific to domestic wastewater. The effluent discharge limits in 8th Schedule are summarised in Table 3.2. All sewage treatment plants design shall take into consideration of the 8th Schedule and shall comply with the proposed limits.

3.2 EQA Effluent Standards

3.2.1 Purpose of Effluent Standards

Effluent standards are used to regulate the disposal of effluent from STP to any receiving waters. The regulation of such discharges will protect receiving waters and their associated aquatic ecosystems, and will also protect public health from the harmful effects of untreated sewage.

The need for these standards has been influenced by the fact that sewage discharges contribute a significant amount of the biodegradable organic matters, suspended solids and ammoniacal nitrogen to the nation’s waterways.

3.2.2 Interpretation of EQA Effluent Standards

The EQA effluent standards have the following characteristics:

a) They represent maximum or absolute values which may not be normally exceeded. For this reason, EQA effluent standards are also referred to as absolute standards

b) Measurement of effluent quality is to be taken using a single grab sample rather than a time averaged composite sample

c) Generally, effluent standards do not allow the flexibility for them to be compromised through dilution and the assimilative capacity of receiving water.

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3.3 Design Requirements to Achieve EQA Effluent Standards

3.3.1 Purpose of Design Requirements

The purpose of design requirements is to ensure that the effluent standards can be met under the normal operations of a sewage treatment plant. The quality of effluent from a STP is expected to vary due to the natural variability in the flows and loads into the plant. Therefore, the design effluent parameter shall be less than the required effluent standards to ensure that, when the plant is under normal operation, any grab sample of effluent will comply with the consent EQA effluent standards.

3.3.2 Design Values

Typical composition of untreated domestic sewage is given in Table A.2, while Table 3.1 tabulates the design influent values to be adopted in the design of a treatment plant.

Table 3.1 - Design Influent Values

Parameter Value (g/capita.day) Value (mg/l)

Biochemical Oxygen Demand (BOD5) 56 250

Suspended Solids (SS) 68 300

Chemical Oxygen Demand (COD) 113 500

Total Nitrogen (TN) 11 50

Ammoniacal nitrogen (AMN) 7 30

Total Phosphorus (TP) 2 10

Oil and Grease (O&G) 11 50

These design values allow for transient reductions in treatment efficiency, due to periodic plant maintenance and unforeseen high impulse of hydraulic and organic loadings on sewage treatment process units. All STP shall be designed to produce final effluents with BOD

5, SS, COD, O&G and AMN values less than or equal to the design effluent values. This is to ensure a high degree of consistent compliance with the required effluent standards. The effluent E.Coli compliance is subject to the sensitivity of the receiving watercourse and of the Commission’s directive.



Table 3.2 - Design Effluent Values

Parameter Effluent Discharge to Rivers / Stream

Effluent Discharge to

Stagnant Water Bodies*Standard A Standard B Standard A Standard B

Absolute Design Absolute Design Absolute Design Absolute DesignBOD5 20 10 50 20 20 10 50 20SS 50 20 100 40 50 20 100 40COD 120 60 200 100 120 60 200 100AMN 10 5 20 10 5 2 5 2Nitrate Nitrogen 20 10 50 20 10 5 10 5

Total Phosphorus N/A N/A N/A N/A 5 2 10 5

O&G 5 2 10 5 5 2 10 5

Notes:NA = Not ApplicableAll values in mg/l unless otherwise stated.* Stagnant Water Bodies refer to enclosed water bodies such as lakes, ponds and slow moving watercourses where dead zone occur.

In cases where treatment plant discharge capacity is higher than the receiving river flow rates, the final effluent quality has to be designed to ensure minimal environmental impact.

3.4 Sewage Pollutants Removal

3.4.1 Biochemical Oxygen Demand (BOD5)

BOD5 is used to measure the biodegradable organic fraction in raw sewage.

Based on standard BOD5

measurement, the oxygen demand measured is usually influenced by the following three (3) phenomena:

a) Oxygen demand by breakdown of soluble carbonaceous matter

b) Oxygen demand by breakdown of suspended particulate carbonaceous matter

c) Oxygen demand by oxidation of ammonia to nitrate by nitrifying bacteria present in the effluent sample

After undergoing biological treatment in the secondary reactor, residual soluble carbonaceous BOD

5 matter present in the effluent reduces

in concentration to below 15 mg/l. Subsequently, nitrifying bacteria populations tend to grow rapidly feeding on ammonia which is present

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in the partially treated sewage. Nitrification may not be complete at levels of 5 mg/l of residual soluble carbonaceous biodegradable matter. It depends on whether sufficient oxygen is available for the oxidation of ammonia to nitrate. Hence, all BOD5 measurements shall adopt nitrification inhibition step to ensure that the carbonaceous oxygen demand is reflected accurately in the overall BOD5 measurement.

3.4.2 Total Suspended Solid (TSS)

Sewage contains solid materials that can settle at the bottom and also give impact on the benthic life. They can also appear in suspension solids form that can increase turbidity and affect the light availability for aquatic life. The amount of solids in sewage is usually measured as “total suspended solids” or TSS. The desired solid removal in sewage treatment plants should not exceed the absolute TSS discharge limit of 50mg/l and 100mg/l for Standard A and Standard B, respectively.

To ensure effluent consistently complies with Department of Environment’s Effluent Limits, provisions must be made to allow for future incorporation of a flocculator in the clarifier. This will enhance clarification performance. Chemical (polymer) can also be added in flocculation clarifiers to further enhance solids settlement in the clarifiers. Otherwise, a dual media filtration system following conventional secondary clarifiers can also be used to ensure that TSS concentration of 20 mg/l to 40mg/l is consistently achieved.

3.4.3 Chemical Oxygen Demand (COD)

COD content reflects the chemically oxidized organic matter. Hence, it includes refractory fractions of organic matter as well as reduced inorganic constituents present in the wastewater. The COD measurement offers quick estimate of carbonaceous material compared to conventional BOD measurement. Additionally, high COD reflects inert reduced inorganic elements and also unbiodegradable organic that comes from industrial contamination. Based on the bi-substrate hypothesis, COD fractions comprising of readily biodegradable, slowly biodegradable and unbiodegradable estimates are adopted in advanced modeling for STP design. Such advanced modeling takes into consideration the treatment process requirements of different COD fractions as it varies in susceptibility to microbial respiration and degradation.

3.4.4 Oil and Grease (O&G)

O&G that is detected in domestic sewage refers to the fraction of organic matter that is soluble in organic solvents such as hexane.



The composition comprise primarily of wax, edible oils and fatty matter of animal or vegetable origins. O&G (mixture of tri, di and mono-glycerides) in its liquid form results in floatable scum formation in treatment systems whilst its solid form causes the clogging of systems.

O&G is separated from raw sewage by provision of grease chambers (be it manual or mechanized scum skimmer removal) at primary treatment stage. Removal at the primary stage is essential to prevent interference of oil particles on biological reactions in the secondary treatment. It also prevents undesirable organic load of extremely slow biodegradable constituents into aerobic systems. Such first line oil and grease removal protects against contamination in the treatment plant as well as in the receiving water.

3.4.5 Nitrogenous Compound

Removal of nitrogenous compounds needs to be considered in STP design. These compounds found in various forms (ammonia or ammoniacal nitrogen, nitrate nitrogen and nitrite nitrogen) could be detrimental to natural water bodies and potable consumption. Total organic nitrogenous compounds in raw sewage typically comprise of nitrogen in the form of proteins, amino acids and urea along with ammoniacal nitrogen. Ammoniacal nitrogen results from the decomposition of organic nitrogen particularly from hydrolysis of urea. Total Kjedhal Nitrogen (TKN) analysis determines the organic nitrogen and the ammoniacal nitrogen fractions.

There are two main biological processes for removing nitrogenous compounds, namely the assimilation of ammonia nitrogen into the microbial biomass and the nitrification-denitrification process. The latter involves two conversion steps. Firstly, nitrification followed by denitrification by microbial heterotrophs that convert nitrates into nitrogen gas. Nitrification comprises two-step oxidation of ammonia nitrogen into nitrate by nitrifying bacteria. All treatment systems shall provide full nitrification and denitrification in the secondary biological reactors with sufficient air supply to facilitate nitrification. This will ensure that effluent discharge complies with the required discharge limits.

3.4.6 Phosphorus Compound

The constituents of total phosphorus compounds in raw sewage are organically bound phosphorus and inorganic phosphorus (orthophosphates and polyphosphates).

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Some fractions of the essential phosphorus nutrients from the influent will be assimilated for microbial growth during secondary biological treatment. However, excessive phosphorus nutrient will occur when above the assimilated with stagnant receiving water bodies (e.g. ponds), which will result in nutrient enrichment and produce harmful algae blooms. Hence, the design for sewage treatment plant effluent that discharges into stagnant water bodies should take into considerations the impact of excess phosphorus contamination.

3.5 Sludge Characteristics and Treatment Requirements

Sludge treatment and management are as important as the sewage treatment to minimise impacts to the environment. Sludge produced from treatment process is usually in liquid form, which typically contains 0.25 to 4.0% of solids, depending on the type of treatment process being used. It also contains grease, fats, organic and inorganic chemicals. High concentrations of certain components will determine the type of sludge treatment process to be used.

Sludge shall be thickened, stabilized, conditioned and dewatered before it is finally disposed off in accordance to requirement stipulated by Department of Environment. The dried sludge must attain a minimum of 20% dry solid content before off-site disposal. Close attention is required when planning and designing sludge treatment processes to ensure bio-solid to be disposed do not contain any harmful substance that will affect the environment. Additionally, stabilization process should be designed to reduce any potential presence of microbial pathogens. Options of ultimate disposal include landfill and land application.

Section 4

Requirements for Physical Design

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4.1 Introduction

The induced physical, chemical and biological reactions that occur in a sewage treatment plant (STP) lead to waste emissions in the following forms:

a) Gases and vapours, some of which contain obnoxious compounds, including bacteria and viruses.

b) noise.c) odour.d) Vibration.e) unwanted solid matter.f) undesirable by-product liquors containing highly concentrated

pollutants.g) heat.

As such, a sewage treatment plant can degrade the amenity of its surroundings, especially in residential areas.

Careful consideration of siting is required to minimise nuisance to the public. Sufficient land needs to be set aside during the planning stage to take into account regional treatment plant development and the proper sewerage planning for housing, commercial and institutional developments.

This section sets out the important factors and considerations associated with the identification of proper sites to locate sewage treatment plants. Typical workflows in the site for sewage treatment plants are illustrated in Figures 4.1 and 4.2. It also addresses the selection of appropriate treatment concepts and sufficient land area requirements for treatment plants in relation to the effluent standards.

4.2 Treatment Plant Siting

4.2.1 Buffer Zones

Suitable buffer distances should separate a sewage treatment plant from its surrounding areas. Buffer Guidelines for the Siting and Zoning of Industries as recommended by the Department of Environment (DoE) should be referred to during the planning of suitable location for treatment plants. The buffer distances recommended in the guidelines depend on the category of industry being considered.

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The provision of buffer zones is essentially an environmental requirement controlled by the relevant planning authority. The agreement of the Local Planning Department on buffer zone and plant siting should be sought at an early stage in the Town and Country planning procedures.

The buffer zone requirements for treatment plants to be observed under this Guideline are as follows. Refer to Figures 4.3 and 4.4 in this section for further clarification.

a) Minimum distance of 30 m from the fence of the treatment plant to the nearest habitable building property line within residential and commercial development.

b) Minimum distance of 20 m from the fence of the treatment plant to the nearest property line within industrial development.

c) Minimum distance of 10 m from the fence of the treatment plant to the nearest habitable building property line if the proposed treatment plant is fully enclosed. A fully enclosed plant is defined in section 7.3.1.

d) A minimum distance of 10 m from the fence of the treatment plant to the nearest habitable building property line if the proposed treatment plant is covered or buried. however, this reduction in buffer requirement does not apply if the nearby habitable buildings are of high rise type. A covered or buried plant is defined in section 7.4.1.

e) Plants with PE less than 150 but are provided with proper odour and noise mitigation measure may have a 10 m reduced buffer at the discretion of the Commission.

The buffer zone can be used for any purpose except permanent habitable buildings. For example, the buffer zone maybe used as a drainage reserve, road or highway reserve, transmission reserve, utility reserve or public park.

In the case where buffer area is to be regularly used by the residents such as car park and playgrounds, proper precautions during design stage must be taken to minimise nuisance such as odour, noise and unpleasant sight to the surrounding environmental. Adequate and proper screening, odour containment and treatment facilities must be provided at the sewage treatment plant to address these issues.



4.2.2 Siting Criteria

The following criteria shall be observed when siting treatment plants.

a) Plants shall be located as far as possible from habitable building to minimise nuisance to the surrounding.

b) Plants shall be located at the lowest point of a sewerage catchment basin so that sewage can gravitate into the plant.

c) Plants shall be located near to a suitable watercourse that is able to receive and assimilate treated effluent from the plant without reducing beneficial uses of the water course downstream.

d) Plants shall be located on an area that is relatively flat or with relatively mild slope across the site that would be useful in promoting efficient hydraulics.

e) The shape of the land area selected shall be such as to minimise the extent of unusable area within the lot.

f) Plants shall not be located in an area that will result in long term operational problems or rapid deterioration of the assets.

g) Plants shall have proper access road leading to it.

h) Plants shall be sited away from the followings:

i) Existing cemeteries and gazetted reserves for cemetery.

ii) Religious centres.

iii) Eating places.

i) Plants shall be located such that sewers are easily connected/conveyed to the proposed site.

j) If temporary treatment plants are to be provided, they shall be located as near as possible to public trunk sewers.

k) For safety reasons, plants shall be located away from children playgrounds.

Emergency bypass shall be provided either at the last manhole or wet-well. The bypass shall discharge to the nearest drain which shall have sufficient capacity to cater for the discharge during rainfall.

4.2.3 Environmental Impact Assessment

An environmental appraisal or environmental impact assessment (EIA) study shall follow Environmental Quality (Prescribed Activities) (Environmental Impact Assessment) order, 1987 under Section 34A of the Environmental Quality Act, 1974 (the EIA order, 1987 and the

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EQA, 1974 respectively). The type and scope of the study will depend on the classification of the plant and the environmental sensitivity of the locality being considered. EIA shall be conducted in compliance with Volume 2 of the MSIG.

4.2.4 Hazard and Operability Studies

hazards and operability (hAZoP) study shall be conducted in compliance with Volume 2 of the MSIG. The type and scope of the study will depend on the classification of the plant.

4.3 Treatment Plant Sizing

4.3.1 Modular Units

Stage development of a STP is governed to a large extend by the timeframe of the overall development plan of the catchments and the size, shape and soil condition of the land reserved for the STP. Modular units will be constructed to cater for the stage development. In determining the appropriate number of modules and corresponding timing for a staged development, it is crucial for the designer to estimate the flow capacity build-up over the entire development phases. The modules must have sufficient capacity to treat the sewage to meet the efficient discharge standard, without compromising the economical viability of operation and maintenance. Too many modules and unit processes will definitely increase equipment maintenance. on the other hand, inadequate modules will result in an inefficient treatment performance due to insufficient capacity and flexibility during the early stage.

Table 4.1 Modularisation Requirements

STP Classifications No. of Modules No. of Trains

Class 1 (<1,000PE) 1 n/a

Class 2 (1,001PE – 5000PE) 1 Max 2

Class 3 (5,001PE – 20,000PE)

Min. 2, Max. 3 Max 2 for each Module

Class 4 (>20,000PE) Min. 4, Max. 10 Max 2 for each Module

Table 4.1 indicates the modularisation requirements in accordance to sewage treatment plant classes to attain an efficient modularisation of sewage treatment plant development. Each module shall be of equal size



and of similar treatment process. If the proposed process is different from the original system, special approval is required from the Commission. Certain unit processes are subject to the modularisation requirements in Table 4.1 while other unit processes are designed for the ultimate phase during the first stage of the development. An example of this is the headworks of a STP designed for the ultimate phase while the secondary processes are added progressively as the future phases come on-line.

Modular treatment plants that are designed with two (2) or more parallel streams must be provided with pipeworks and valves to isolate each stream of unit process during maintenance and major shut down without interfering normal operation of the remaining stream.

4.3.2 Standby Units

To avoid significant down time in sewage treatment and overloading of the process units, standby units shall be provided for the following processes:

a) Inlet Works/Pumps

b) Screen Facilities

c) Grit Chambers

d) Biological Treatment

e) Secondary Clarifiers

f) Sludge Facilities

The common standby mechanical equipments are as follows:-

a) Pumps (raw sewage, effluent, sludge, etc)

b) Mechanical screens

c) Blowers

d) Any other mechanical equipment

Detailed requirements of standby units shall follow the requirements in Section 5.

4.3.3 Back-up Capacity

The back-up capacity provided shall be such that when one unit process is taken out of operation, the remaining units shall not be overloaded beyond 50% of their rated capacities.

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4.3.4 Design Flow

It is recommended that unit processes that are designed on average flow basis are sized to allow for infiltration in accordance with MS 1228. Conveyance networks shall be sized to cater for peak flows, except for those networks located downstream of an equalisation tank. All unit processes shall be designed based on the maximum ultimate design flow.

4.4 Land Area Requirements

The recommended land area requirements for various sewage treatment plants capacities are derived from relevant treatment process concepts and also taken into consideration other design criteria.

The land area requirements and buffer allowance for temporary sewage treatment plants maybe reduced at the discretion of the Commission on a case by case basis.

4.4.1 Class 1 and 2 Plants

The recommended land area requirements for Class 1 and 2 plants (up to 5000 PE) are given in Table 4.2 and Table 4.3 respectively. The net area does not include the 30 m buffer zone surrounding the plant, but does include appropriate set backs and access paths within the plant. The area requirements given are sufficient to achieve an effluent conforming to Standard A discharge requirements. It is important that allowance is made for sufficient buffers in planning approvals, to avoid future complaints in relation to the siting of the plant.

4.4.2 Mechanised Class 3 to 4 Plants

For Class 3 and 4 plants with mechanised systems, the recommended land area requirements are given in Table 4.4 and 4.5. These systems are to be used in normal developed and urbanised areas. The net area does not include the 30 m buffer zone surrounding the plant, but does include appropriate set backs and access paths within the plant. The area requirements given are sufficient to achieve an effluent conforming to Standard A discharge requirements. It is important that allowance is made for sufficient buffers in planning approvals, to avoid future complaints in relation to the siting of the plant.



4.4.3 Aerated Lagoons and Stabilisation Ponds

For aerated lagoon and stabilisation pond treatment systems, the recommended land area is as shown in Table 4.6. Sufficient buffer areas shall be allowed for surrounding the plant as per paragraph 4.2.1.

4.4.4 Imperfect Sites

The recommended land area requirements represent an ideal case, where it is possible to locate the STP within a rectangular land area that is relatively flat. In practice, the allocated land may be irregular in shape, sited in low lying or undulating to steep valley terrain. For such cases, suitable adjustments to the land area requirement have to be made.

Thus, the shape and elevations of the land allocated for the STP development must be determined during planning stage so that the configuration of the STP can be planned properly in order to allocate adequate land for the purpose. This also enables estimates for additional land required. It may also be required to cut or fill operations to level the land.

4.4.5 Reduced Land Areas for STPs

The area requirements, as stipulated in Table 4.2, 4.3, 4.4, 4.5 and 4.6, must be adhered to as strictly as possible. The required areas in these tables include appropriate setbacks and access paths within the plant. however the areas have not include any buffer zone surrounding each plant as indicated in Section 4.2.1.

In developments where land is really a constraint the Commission may consider for a reduced land area requirement. The project proponent will have to demonstrate clearly the need for a reduced land area before an approval can be granted. For this case, detailed design calculations of all unit processes, together with the proposed layout, shall be submitted at the planning stage for consideration of approval by the Commission. otherwise, the land area required under these guidelines must be followed.

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Table 4.2 Land Area Requirements for Class 1

Population Equivalent

Land Area Requirement *

(m2) (acre)

100 210 0.052

150 285 0.070

200 360 0.089

250 430 0.106

300 485 0.120

350 545 0.135

400 600 0.148

450 655 0.162

500 700 0.173

550 745 0.184

600 790 0.195

650 835 0.206

700 870 0.215

750 905 0.224

800 940 0.232

850 980 0.242

900 1010 0.250

950 040 0.257

1000 1070 0.264

Note: * The required area only includes appropriate setbacks and access paths within the plant but not the buffer zone surrounding each plant as indicated in Section 4.2.1.



Table 4.3 Land Area Requirement for Class 2



(m2) (acre)1100 1115 0.2761200 1160 0.2871300 1200 0.2971400 1240 0.3061500 1275 0.3151600 1310 0.3241700 1340 0.3311800 1370 0.3391900 1395 0.3452000 1420 0.3513000 2226 0.554000 2671 0.665000 3076 0.76

Table 4.4 Land Area Requirements for Mechanised Class 3 Plants



(ha) (acre)

5001 0.31 0.76

6000 0.40 0.99

7000 0.49 1.21

8000 0.59 1.46

9000 0.69 1.71

10 000 0.78 1.93

15 000 1.00 2.47

20 000 1.19 2.95


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Table 4.5 Land Area Requirements for Mechanised Class 4 Plants


Land Area Requirement *(ha) (acre)

20 001 1.19 2.9525 000 1.37 3.3830 000 1.53 3.7935 000 1.81 4.4840 000 1.97 4.8845 000 2.12 5.2550 000 2.23 5.5255 000 2.37 5.8460 000 2.52 6.2265 000 2.67 6.6170 000 2.93 7.2375 000 3.27 8.0780 000 3.49 8.6185 000 3.69 9.1290 000 3.89 9.6195 000 4.07 10.06100 000 4.25 10.49110 000 4.57 11.29120 000 4.87 12.02130 000 5.14 12.70140 000 5.39 13.32150 000 5.63 13.90160 000 5.84 14.44170 000 6.05 14.95180 000 6.25 15.43190 000 6.43 15.89200 000 6.60 16.32250 000 7.36 18.20300 000 7.98 19.73450 000 9.36 23.14




Table 4.6 Required Land Area for Stabilisation Pond and Aerated Lagoons


Standard A* Standard B*

(ha) (acre) (ha) (acre)

2000 0.48 1.18 0.45 1.10

3000 0.69 1.69 0.59 1.45

4000 0.89 2.20 0.71 1.75

5000 1.09 2.68 0.82 2.04

10 000 2.03 5.01 1.31 3.24

15 000 2.92 7.2 1.72 4.25

20 000 3.78 9.3 2.09 5.16

25 000 4.62 11.4 2.42 5.99

30 000 5.45 13.5 2.74 6.77

35 000 6.26 15.5 3.04 7.50

40 000 7.05 17.4 3.32 8.2

45 000 7.85 19.4 3.59 8.9

50 000 8.63 21.3 3.86 9.5

55 000 9.40 23.2 4.11 10.2

60 000 10.16 25.1 4.36 10.8

65 000 10.92 27.0 4.60 11.4

70 000 11.68 28.9 4.83 11.9

75 000 12.42 30.7 5.06 12.5

80 000 13.17 32.5 5.28 13.1

85 000 13.91 34.4 5.50 13.6

90 000 14.64 36.2 5.72 14.1

95 000 15.37 30.0 5.93 14.6

100 000 16.10 39.8 6.13 15.2

110 000 17.54 43.3 6.54 16.2

120 000 18.97 46.9 6.93 17.1

130 000 20.38 50.4 7.31 18.1

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Table 4.6 Required Land Area for Stabilisation Pond and Aerated Lagoons (Continued)


Standard A* Standard B*

(ha) (acre) (ha) (acre)

140 000 21.79 53.8 7.69 19.0

150 000 23.18 57.3 8.05 19.9

160 000 24.57 60.7 8.40 20.8

170 000 25.95 64.1 8.75 21.6

180 000 27.32 67.5 9.09 22.5

190 000 28.68 70.9 9.43 23.3

200 000 30.04 74.2 9.76 24.1




Figure 4.1 STP Land Area Requirements for Planning Layout Approval for New Development

Start

End

Determine catchmentserved

Determine ultimate PE

Identified effluentrequirement

Apply sitting criteria

Use land area fromTable 4.2

(Class 1 plants)

Use land area fromTable 4.3,4 and 5

(Class 2 to 4 plants)

Use land area fromTable 4.6

(pond systems)

Is development> 2000 PE?

Is developmentin urban area?

N Y

N

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Figure 4.2 STP Land Area Requirements for Structure PlansRequirements for Physical Design

egareweS naisyalaM 4 emuloV 24 senilediuG yrtsudnI

Figure 4.2 – STP Land Area Requi rements for Structure Plans

Determine natural drainage catchments

Calculate ultimate catchment PE

Determine suitable receiving waters

Identify e�uent standards

Look up land area requirements in

Tables 4.2, 4.3, 4.4 or 4.5

Table 4.3, 4 and 5: Greater than1,000 PE

for urban areas

Table 4.2: Up to 1,000 PE

Table 4.5: For remote area siting of STP

Apply siting criteria

Select and zone suitable site

Consider multi-use of bu�er areas

Reserve land for STP

Local Plan Formulation

Start

End

Perform the next two steps concurrently

Determine natural drainage catchments

Calculate ultimate catchment PE

Determine suitable receiving waters

Identify e�uent standards

Look up land area requirements in

Tables 4.2, 4.3, 4.4 or 4.5

Table 4.3, 4 and 5: Greater than1000 PE

for urban areas

Table 4.2: Up to 1000 PE

Table 4.5: For remote area siting of STP

Apply siting criteria

Select and zone suitable site

Consider multi-use of bu�er areas

Reserve land for STP

Local plan formulation

Start

End

Perform the next two steps concurrently



Figure 4.3 Guidelines For Buffer Zone



Figure 4.3 Guidelines For Buffer Zone

Treatment Plant Site Buffer Zone 20m Min. Industrial Plot

5m Min.Access And Screening

STW Fence Factory FenceOpen Treatment

Plant

Plants Situated In Industrial Areas

Note : The buffer area can be used for roads, drains, utility reserve, agricultural or other similar purposes.

ZoneTreatment Plant Site Buffer Zone 10m Min. Residential / Commercial Plot

5m Min.Access and Screening

Enclosed Plant STW FenceProperty Boundary

Treatment Plant Site Buffer Zone 30m Min. Residential / Commercial Plot


Open Treatment Plant

STW Fence

Beautification

Property Boundary

Plants Situated In Residential / Commercial Areas

Treatment Plant Site Buffer Zone 10m Min. Residential / Commercial Plot


STW Fence PropertyBoundryBuried / Covered

Plant

Treatment Plant Site Buffer Zone 30m Min. Residential / High Rise

5m Min.Access and Screening

Enclosed Plant STW FenceProperty

Boundary

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Figure 4.4 - Plan View of Buffer Zone Requirements



Figure 4.4 Plan View of Buffer Zone Requirements

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4.5 Mechanical and Electrical Requirements

Some general guidelines on the design and installation of mechanical and electrical equipment are outlined below.

4.5.1 Mechanical Installation

I) Design Considerations

The designer shall consider incorporating the following criteria:

a) The design shall simplify the equipment required, control system, maintenance and operational procedures, while fulfilling the intended performance and standard of service.

b) The brand and models of major drive equipment (e.g.: pumps, blowers, aerators, clarifier scrappers, etc.) shall be those approved by the Commission.

c) The types and makes of equipment provided throughout the facility shall be standardised, whenever possible.

d) only new and genuine equipment shall be provided.

e) Equipment sizing and selection shall minimise energy and other consumables costs.

f) The minimum economic life of equipment.

g) Material selection shall be in accordance with the Commission specifications or/and other relevant international standards.

h) Components shall be robust and suitable for use. Where thin metal sheeting is used, it shall be stiffened to minimise distortion.

i) Water storage tanks shall not be placed on the roof top of any control room; all water supply system shall be homed with separate entrance.

II) Installation

a) The base frame of rotational equipment or any equipment that may induce vibration shall be provided with anti-vibration mount.

b) All moving parts shall be designed and installed in a manner that is inherently safe to operate.

c) Foundations shall be adequately designed to include all dynamic load and anchored to withstand all loads imposed by the equipment. Reinforced concrete foundations are preferred.

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d) Equipment shall be accurately located, levelled and secured by holding down bolts. non-shrink grout shall then be used to complete the foundation. In some cases, a resilient connection to the foundation is required, in which case, the manufacturers instructions shall be followed.

e) holding down bolts shall be of stainless steel and shall be of a minimum Grade 316 if in contact with sewage.

f) Puddle collar is required for all pipe passing through all walls.

g) Appropriate joints shall be provided in all pipeworks to facilitate the removal of equipment, meters, valves and other special items without dismantling the entire pipeline.

h) Valves shall be provided for isolation purpose.

i) outdoor and dry installation pump shall be provided with housing.

j) The designer must ensure that the unit processes are arranged in such a way to prevent/reduce criss-crossing of piping works, unnecessary bends, choking of interconnected pipe and excessive hydraulic losses through the system.

k) The platform level of mechanical equipment and controllers of any process unit shall be located above design flood level.

4.5.2 Vibration

All revolving parts shall be properly balanced both statically and dynamically so that in running up to, at full normal operating speeds, and at any loads up to the maximum there shall be no undue vibration anywhere in the machine or transmitted to the adjacent structure. The criteria adopted for vibration severity shall be the RMS value of the vibration velocity in millimeters per second.

The bare frame of rotational equipment or any equipment that may induce vibration shall be provided with anti-vibration mount. Where rotational equipment or equipment which may induce vibration is connected to piping, then vibration isolator shall be provided.

4.5.3 Noise

noise levels from machinery shall comply with the Factories and Machinery (noise Exposure) Regulations 1989 and occupational health and Safety Act. noise control measures and appropriate safety protection for operators must be provided where necessary.



noise control measures shall be implemented to control the generated noise level to below 65 dB at a distance of 2 m from the boundary of the housed noise source at all times. Additionally, the general noise levels generated shall be measured 10 m from any point of the plant site within the nearest public space and/or occupied space to an acceptable level stipulated by the appropriate regulators. Silencers and acoustic enclosures shall be provided as required to achieve the above noise level reduction.

Enclosures used to achieve these noise reductions shall permit ready access to the equipment for routine maintenance. Adequate air ventilation shall be provided to allow cooling of the enclosure to prevent overheating of the equipment/motors.

noise level measurement shall be made with a sound level meter which complies with BS En 60651 and which is fitted with an ‘A’ weighting network. The sound pressure level shall be measured in dB (A).

noise level for all electronically operated electrical device such as soft starters, variable speed drives and others shall be conform to IEC, En. Thus it shall fulfil all EMC Immunity requirements complying with En500082-1, En50082-2, En50082-3.

4.5.4 Safety Around Equipment

All designs and equipment shall be made and installed with safety in mind. nothing in this Design Guidelines shall remove the designer’s obligation to incorporate equipment or designs that would increase the safety of the plant.

The installation layout and equipment design shall not allow any item of equipment to be so positioned that danger could arise to operating personnel and equipment during normal operation and maintenance. Particular attention shall be paid to the positioning of switch board, control panel, cables, switch gears, lighting, small power, rotational equipment, other electrical equipment and accessories.

All facilities shall be designed to comply with the occupational Safety and health Act 514, 1994; properly designed treatment plants will enable the operator to safely handle the treatment plant throughout its design life. The plant shall also be designed to comply with other related Acts such as IEE, Akta Bekalan Elektrik 1990 (Akta 448) and Peraturan-Peraturan Elektrik 1994.

Safety level for all electronically operated electrical device such as soft starters, variable speed drive and others shall conform to IEC, En, uL, nFC and VDE. Thus it shall fulfill En 50178, En 60204-1, En 60950 (2000, 3rd edition), IEC 61800-5. Where appropriate, IEE and Akta 448 (1990) and Peraturan Elektrik 1994 must be complied within all electrical installation.

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The following shall be provided:

a) All moving parts shall be protected by suitable guards. Where inspection is required, an open mesh with frame and suitably supported maybe used. The maximum aperture of the mesh shall be 6 mm.

b) All guards shall be readily removable and replaceable to they correct orientation only. however the guard shall be designed with features to prevent accidental dislocation from its’ original position. The fasteners when dropped during dismantling, must be easily retrievable and should not damage any equipment or endanger personnel, else fixed fasteners shall be used.

c) An emergency stop button, preferably of mushroom head type shall be located adjacent to all equipment. More than one emergency stop button shall be used, if access around the item is restricted.

d) Long items, such as conveyor belts, shall have an emergency lanyard applied to each accessible length of conveyor.

e) Surfaces which are greater than 50°C shall be guarded.

f) Permanent warning signs shall be posted at visible location at all dangerous areas and shall clearly indicate the nature of risk at that area. This includes warning signage at digesters area, high tension room, low voltage room, generator room and other hazardous areas.

g) Clear working space as recommended in Figure 4.5 shall be provided.

h) Automatic Co2 discharge triggered by heat and smoke sensors shall be installed in high voltage switch room, transformer room, low voltage switch room and generator room.

i) high tension room shall have signage to clearly indicate the purpose of the room and also safety signage to prevent unauthorised entry.



1 m or 1.5 W or whichever greater

Wall

Equipment

Equipment



W

L

Figure 4.5 - Clear Working Space

Wall

4.5.5 Motors, Controllers and Motor Starters

I) Motors

a) Provide readily replaceable anti-condensation heaters for motors that do not require frequent operation.

b) At least three thermistors to be provided for motors which are >50 kW.

c) Electrical motors should be rated as continuous run.

d) Motors > 22kW shall be protected with soft starter or variable speed drive.

e) Where water hammer prevails, frequency inverter shall be provided.

f) The appropriate cooling system based on the requirements of the equipment shall be provided.

II) Controllers

a) Start push buttons to be green and recessed

b) Stop push buttons to be red and recessed

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c) Emergency stop push button to be red and mushroom head type

d) on signal lamps to be green

e) oFF signal lamps to be red

f) Trip signal lamps to be amber

III) Motor Starters

a) up to 3.7 kW – Direct-on-Line starters

b) Above 3.7 and up to 7.5 kW – Star/Delta starters

c) Above 7.5 and up to 22 kW – Auto-transformer starters

d) More than 22 kW – Soft starter

e) Above 50 kW – Variable speed drive is preferred

Soft starting of motors above 30kW or greater in size is necessary to minimise power disturbances (e.g. power surge) and process disturbances (e.g. water hammer). Variable speed drive shall be considered at application where variable capacity maybe need to enhance the process flexibility, for example, aeration device and blowers.

4.5.6 Power Supply Systems

Power supply to sewage treatment plants shall be as follows:

Category Supply Requirements Sewage Treatment Plant

A Single incomer with properly design control overflow system during power failure (all electrical control system shall be located above design flood level)

All Class 1, 2 and 3 STPs

B B1) Single incomer with diesel generators for back-up supply.

STP Class 4

B2) Single incomer with control overflow system and genset contribution fee.

a) Where a SCADA system is provided and essential parameters are to be monitored during power supply interruptions, a DC supply or a uPS (uninterrupted power supply) must be provided.



b) Batteries/uPS shall have the capacity to operate the SCADA system for a minimum 6 hrs during power failure to safe last event, to monitor the essential parameters and to enable early warning system.

c) no direct tapping of power is allowed from distribution board (DB). Proper protection shall be provided for any direct connection from switchboard. Earth leakage current breaker (ELCB) shall be provided for DB.

d) The power system distribution shall be designed to achieve a minimum power factor of 0.9. For phase development, the plant and power system distribution shall be designed for maximum load and installed in appropriate modular unit to ensure that the minimum power factor is achievable at all phases of operation.

e) Equipment shall be protected by either moulded case circuit breaker (MCCB) or miniature circuit breaker (MCB) based on its suitability. Electrical design calculations shall be provided to justify each selection.

f) Every control circuit shall be protected with separate MCB.g) TnB meter panels shall be installed close to the site entrance or

adjacent to but physically separated from the main switchboard. Suitable flexible steel conduit with approved adaptors shall be supplied and fitted between the main switchboard.

h) All metering panel shall be located flush with the fence and door opening from outside to enable TnB inspector to read the kWh and kVAhr reading.

i) Provide earthing connected with Current Transformer (CT) for Large Power Consumer (LPC) (i.e. consumption with more than 100A or 10kW).

j) To provide earthing connected to ELCB/RCCB/ELR or over Current & Earth Fault relay to protect overcurrent and surge current to all wiring connected to TnB metering panel for Large Power Customer (LPC) or ordinary Power Customer (oPC). Test for earthing system shall be below or equal 1 ohm.

4.5.7 Back-up Generator

a) If diesel generators are to be provided they shall be used for essential loads only (these include influent pumping in pump station, feeding pumps in balancing tank, decanter for SBR; minimum 30% aeration requirement; emergency services system, essential lighting and ventilation system.

b) Where generators are installed, they must be accompanied with the necessary supporting systems, including automatic cut-in

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in the event of mains failure, fuel storage and transfer; and if installed indoors, including ventilation, fire detection/protection and working alarms.

c) In the event of power interruption/failure; when diesel generators are used, the SCADA shall be powered by uPS or DC battery.

d) For plants ≥ 100 000 PE, the capacity of the back-up generator may vary provided detail calculation must be provided to justify that sewage can be kept in aerobic condition for a maximum duration of 6 hours

e) Gen-set shall be sized to the incoming TnB voltage requirement.

4.5.8 Switchgear and Control Gear Assemblies

a) For simplicity, separate the Supply Authority Metering from the main switchboard

b) Electro galvanised plates to be used to protect materials against corrosion due to high humidity

c) Panel isolators and door locks to be capable of padlocking open with 6 mmc - hasp padlock

d) use separate panel boards for general purpose light and power

e) Group all motor starting equipment for an area into multi-motor, starter control board

f) Cabinets are to be constructed to prevent the ingress of insects and vermin

g) For incomer above 400 A, provide over current and earth fault protection on all starter circuits in excess of 200 A

h) Where a circuit has a main and standby supply, provide an isolator in each supply circuit

i) Junction boxes for submersible pumps and float controls shall be above the floor or any possibility of flood level and must not be located in the wet well.

4.5.9 Control Cabinets

(I) General

a) Provide 900 mm minimum clearance between an open door and any fixed object.

b) Provide 900 mm clearance between open cabinet doors of facing cabinets.



c) Front access cubicles to have the electrical clearance distances between door mounted equipment and gear tray mounted equipment as specified in the regulations.

d) Mount all equipment inside cabinets on gear trays.e) All cabinets to have a base frame, at least 50 mm high.f) All control panels shall be provided with phase sequence

relay. g) All control rooms shall be isolated from invasive environment

of the sewerage system, where carbonisation, corrosion or condensation may occurs that lead to short-circuiting.

h) height to be no greater than 1600 mm internally.i) Mount cabinet on reinforced concrete plinth, 200 mm minimum

above ground.j) Provide a reinforced concrete paved area for the full width of

the cabinet and extending 1 m in front of the cabinet doors, when they are opened.

k) Cable entry from the top only.l) Provide forced ventilation fan for cubicles housing PLC

equipment.m) Provide ventilation for variable speed drives and soft starters.n) natural ventilation is suitable for direct-on-line, star-delta and

auto transformer starters.o) The minimum acceptable IP rating and tests required shall be

clearly specified.

(II) Outdoor Cabinets

a) Self contained, free-standing, weatherproof cabinets to be constructed of marine grade aluminium, stainless steel grade 316 or glass reinforced plastic.

b) Mount control indication and alarm facilities on internal doors enclosing compartments housing electrical plant and equipment.

c) Provide external doors with security locking facilities.d) Provide double roofs on cabinets to reduce solar effects.e) Wall mounted outdoor weather proof control panel shall come

with an awning extended by at least 2 m from the wall.f) Floor mounted outdoor weather proof control panel shall come

with a roof extended 2 m from the panel.g) External weather proof control panel of equal and more than

100 A shall be provided with permanent Co2 fire extinguisher.

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4.5.10 Control Requirements

This section outlines the general philosophy on control requirements for the whole facilities.

NO. TYPE OF PLANTEWS + PC

(monitoring) / Data Logger

SCADA

1. network Pumping Station (nPS) < 100 000 PE ≥ 100 000 PE

2a. Sewage Treatment Plant Class 3 STPs Class 4 STPs

2b.Sewage Treatment Plant requires full automation, e.g. sequencing batch reactor.

Class 1, 2 and 3 Class 4 STPs

2c. Sewage Treatment Plant (Standard A) Class 1, 2 and 3 Class 4 STPs

Notes : EWS – Early Warning System

SCADA – Supervisory Control and Data Acquisition

I) General Considerations

a) PLC shall restart automatically once the power supply reinstate after a power supply interruption.

b) PLC shall be equipped with manual over-ride features.c) Continuously running drives shall restart automatically after a

power supply interruption.d) Plant to have time delayed restarting sequences for equipment

to avoid overloading power supply.e) Transducers shall be used to sense the signal for related warning

alarms.f) Trip and shutdown to be measured by separate relays.g) The operating status and condition of the process shall be verified

by measuring appropriate performance indicator and not by inference.

h) SCADA room shall be air-conditioned.i) Telephone line must be laid during construction for all sewerage

works to be equipped with SCADA.



II) Manual Control

a) Interlocks shall be provided to prevent damage to the equipment during equipment start up, for example, bearing overload, overheated, temperature, loss of cooling water, no flow when operating.

b) Selector switches to be provided at one location so that an equipment can be manually operated from that location.

III) Drive Systems

a) Each drive must be independently provided with the following features :

i. on - starts and runs the drive ii. oFF - stops the drive iii. AuTo - operates the drive in accordance with

automatic control systemb) Indicate operation by an ammeter c) Record running hours with a local indicator and by computation

in a central SCADA system where applicable.d) Local annunciation on motor starter of each fault condition.e) Record kilo-Watt.hour (kWh) of major drive equipment.

IV) Automatic System Control Facilities

a) Displays operator adjustable parameters, examples set point of top water level in a tank and the target dissolved oxygen level for a process.

b) Ability for the authorised operator to adjust the set point of operator adjustable parameters. A “default” value should always be provided.

c) Displays to advise operator of the set points of non-operator adjustable parameters. Examples would include the overflow level on a tank and the trip temperature for a bearing.

d) Displays measured values by all instruments, used to measure flow, level, Do, ph, temperature or applicable parameters.

e) The process control sequences must ensure system problems such as water hammer overtorque or overpressure the equipment of air compressors. Time delayed in starting and stopping of equipment where multiple duty units are installed, use a value with slower rate the final stage of closing, vary the speed of equipment during starting and stopping are some of the option for consideration in careful process automation.

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4.5.11 Supervisory Control and Data Acquisit ion Systems (SCADA)

SCADA is the acronym for Supervisory Control and Data Acquisition. The term refers to a large-scale, distributed measurement (and control) system. SCADA systems are used to monitor or/and to control chemical, physical or transport processes. The following briefly describe the requirements of SCADA while the detail requirements of SCADA are listed in Appendix C.

The term SCADA usually refers to a central system that monitors and controls a complete site. The bulk of the site control is actually performed automatically by a Programmable Logic Controller (PLC). host control functions are almost always restricted to basic site over-ride or supervisory level capability. Provision of SCADA system shall be in accordance with Section 4.5.10.

I) Control Systems

a) All equipment shall be tagged in the SCADA system.b) Develop sequential function diagrams to specify the control logic

to suit the process operation for each system.c) Check the process operation against the resulting sequential

function diagram.d) PLC programs to be written in modular form to aid fault finding

and commissioning.e) Design programs to be ‘fail to safety’. That is, PLC failure will

cause plant to stop.f) on restoration of supply, all controlled system shall be returned

to the ready position before automatic restart takes place.g) Bench test all application programs for PLC, before program

installation on site.h) Conduct functional control circuits tests for all items of

equipment.i) Ensure PLC programming software licences are delivered.j) Provide paper copy listing of all PLC application programs and soft

copies of application program (two copies of each required). k) Despite the PE, all plants which requires automation and control

shall be provided with human machine interface (hMI) at site.

II) Supervisory Systems

a) Where supervisory systems are used, schedule all graphic displays required to control plant using columns to define:

i) Graphic name



ii) Information displayed

iii) Control features

b) update times for screens to be not more than one second.

c) nominate the alarm title to be used/displayed for each process-generated fault input or fault generated internally by the PLC program.

d) nominate critical and non-critical alarms and the method of differentiation. Examples would be: nominating an alarm on a limit which has been reached as critical and an alarm on a limit which is being approached as non-critical; differentiated by, for example, red/amber lights or horn/bell).

e) At least eight variables to be displayed on a trend graph simultaneously for ease of monitoring and comparison. This is a measure of the level of software sophistication which should be expected.

f) Supervisory system to log running hours for all plant items.g) nominate the reports to be generated for plant operation,

management and history. For example, reports to be daily, weekly and monthly and the list of parameters to be reported on in each.

h) Alarm analysis, that is, frequency of occurrence, similar plant faults, etc, to be provided as part of the supervising programs.

4.5.12 Early Warning System (EWS)

The EWS is used to monitor the status of the equipment operating inside the treatment plants such as pumps and aeration equipment. It shall act as the means to communicate information via Short Messaging Service (SMS), e-mail or via other telecommunication mean to technical staff for the fast recovery of the treatment system.

EWS system shall be able to transmit digital and analog values from the remote module to the operator through their inputs (equipment) via SMS and e-mail messages in text mode. The modules shall be able to interpret SMS message from the operator to activate or deactivate long distance machine (remote control).

4.5.13 Instrumentation

Provision for instrumentation shall be in accordance with the following Table 4.7. Instruments shall be installed in such a way that they can be removed for maintenance without interrupting the process.

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Table 4.7 Required Process Instrumentation

Treatment Unit Instrumentation STP Class

Inlet Pump Station Level/ PressureFlow MeasurementGas Detector (h2S, Co2, o2 & Combustible gases)

AllAll4

Aeration Do/ph/ TurbidityTemperature

44

Blower Air flow/ pressure/ temperature/rpm

All

Decanter Position Indicator /Speed AllEffluent Flow Measurement AllSludge (WAS/RAS) Flow Measurement 4Electrical Drive Am/Volt/hR/kW/Power Factor

meterAll

Disinfection Dosage/Transmittance /Flowrate/outlet water level indicator

All

Polymer Dosage/ Level Indicator/ Flowrate

All

Sludge Feed Flowrate/ Pressure All

For STP with PE 10 000 and above, a digital power meter is required to be installed at all individual panel of major equipment such as raw sewage pump, air blower, aerators, mechanical dewatering unit etc. The digital power meter shall be able to monitor the following:

Real-Time Readings Current, Voltage, Real Power, Reactive Power, Apparent Power, ThD (V and I)

Energy Readings Accumulated Energy (Real kWh, Reactive kVarh, Apparent KVAh)

Demand and peak Readings

Current, Real Power, Reactive Power, Apparent Power

other: Power Factor, Load operating Time

All parameters measured as mentioned must be retrievable at all time.



4.5.14 Cables and Cabling Installation

I) General

a) Segregate cables into the following categories:

i) power (less than 1000 V phase to phase)

ii) instrumentation/telemetry

iii) control

b) Wherever possible, use a separate cable-support system for each cable category.

c) Separate such cable support systems by minimum clear distances of 300 mm.

d) When one cable support system has to be used, separate cable categories by minimum clear distances of 150 mm.

e) Secure cable at 900 mm intervals for horizontal runs and 300 mm for vertical runs.

f) Cable ties shall be made of non-corrosive material and if exposed to the environment, shall have uV protection.

g) All cables shall be at least of double PVC protection, and if exposed to the environment then armoured cable shall be provided.

II) Instrumentation

a) use separate cables for digital and analog signals.b) Marshal cables in a process or geographical area into junction

boxes.c) use multipair cables between areas.

III) Buried Cables

a) Install cables without trees or through joints, unless approved.

b) All buried cables shall be laid in ducts.

IV) Underground Ducts

a) Construct road crossings from uPVC conduit of minimum 100 mm diameter with 900 mm cover and encased on all sides with 150 mm concrete.

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b) All other ducts to be PVC conduit laid with a minimum cover of 600 mm. Ducts to be bedded in 75 mm sieved sand.

c) Provide draw strings in all ducts.

d) Provide cable pits to suit cabling layout and to allow drain-in of cables through the duct work. Cable pits shall be provided no greater than 100 m apart. They shall be fitted with trafficable cast iron covers and equipped with drainage.

e) Seal ducts into buildings with approved systems providing a fire rating of 30 minutes.

(V) Conduits

a) All cabling within buildings or structures where cable trays are not permitted, and in all external locations, shall be installed within conduits.

b) Conduits installed externally shall be arranged to minimise their length and exposure. PVC heavy duty conduit is permissible, where it is protected from physical damage and uV. otherwise, metal or flexible conduits shall be used.

c) use flexible steel reinforced conduit for connections, where relative movement and removal for maintenance has to be considered.

VI) Cable Support Systems

a) Ensure cable support systems in electrical switch rooms, equipment (for example, pump) rooms and service galleries.

b) When run in common service galleries, ensure cables are not adjacent to hot services.

4.5.15 Earthing and Lightning Protection

a) Provide earthing and lightning protection to meet local regulations.

b) use a specialist inspector to verify the installation.

c) Earthing test results shall be submitted and results shall be below or equal to 1 ohm.

d) Lightning arrestor test results shall be submitted and results shall not more than 5 ohms.

e) Earthing and lightning arrestor chamber shall be of pre-cast material.



4.5.16 General Purpose Power

Provide general purpose power socket outlets as follows:

a) Single phase outlet rated at 10 A adjacent to, or inside each control cabinet and within 10 m of all equipment installations.

b) Three phase outlet rated at 50 A within 20 m of every screen, sludge scraper, clarifier rake, grit collector and conveyor.

c) Three (3) phase (with neutral) outlet rated at 50 Amp shall be provided at an interval of at least 20 m.

d) These outlets shall be water proofed industrial type switch socket outlets (SSo).

4.5.17 Manuals, Drawings and Labelling

a) Provide equipment manuals that are specific to the plant and instrumentation supplied.

b) System manuals describe the way each system manages the individual items of plant. Ensure these are available in draft form, before testing and commissioning commences.

c) Provide plant function diagrams, electrical system, electrical circuit, Process and Instrumentation Diagram(P&ID), instrument loop diagrams, electrical design calculations and single line diagrams with endorsement by qualified person, before the plant is pre-commissioned.

d) All plant and equipment are to be provided with inscriptions and labels to facilitate understanding and safe operation and to satisfy the requirements of any standards and regulations applying to the works. Labelling includes:

i) inscriptions on equipment, cubicles, instruments, process controllers and on small equipment such as relays, control switches, indicating lights, etc

ii) identification of cables at both ends and along their lengths

iii) identification of terminations for cable cores and cubicle wiring in accordance with the circuit diagrams

e) Drawings submitted shall show all unit processes to be constructed, and equipment to be installed based on the ultimate capacity of the sewerage system, especially for phase development where the construction of unit processes and installation of equipment will be based on phasing.

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f) For treatment plant with PLC/SCADA systems, ladder diagram, programme source codes and programming console unit shall be provided before pre-commissioning of the treatment plant.

4.5.18 Hazardous Areas

a) A plan setting out various hazardous areas and classes of electrical hazard is required. For example, flameproof area in the vicinity of anaerobic digesters/sludge gas compressors, chemical storages or laboratories.

b) Ensure the plant and methods of construction and installation conform to the requirements of each defined area, as this plan will be used by the Supply Authority to inspect the area for conformance.

4.6 Material Requirements for STP Structures and Installations

Materials permitted for structural fabrication in treatment plants are concrete, reinforced concrete, steel, fibreglass reinforced plastic and aluminium. The requirements for such materials shall be in accordance with information provided in the following sub-sections. Any others material used for STP structures and installations shall obtain special approval from the Commission.

Structural design of treatment plant structures shall be submitted by registered professional engineers. They shall be in accordance with the requirements and standards given in this section and any other relevant standards, as well as, sound engineering practices.

4.6.1 Concrete and Reinforcement

a) Concrete structures shall be designed in accordance with MS 1195, except that concrete structures for retaining sewage and other aqueous liquids shall be designed in accordance with BS 8007.

b) Concrete shall generally comply with the relevant requirements in MS 523.

c) Concrete for structures retaining sewage shall have a strength grade not less than grade C35A. Strength grades higher than C35A may be specified as required by the Commission.



d) Concrete for structures retaining sewage shall be designed for buoyancy due to ground condition.

e) Concrete for purposes other than structures retaining sewage shall have a strength grade not less than grade C20 where unreinforced, and not less than grade C30 where reinforced. Strength grades higher than the minimum may be specified as required by the Commission.

f) Concrete structures retaining sewage, shall be lined with high alumina cement mortar of 20 mm minimum thickness or other approved liners/lining materials.

g) Concrete and cement mortar exposed to soils or groundwater shall be made using a cement suitably resistant to sulphate attack, as specified in this section. Where part of a concrete structure is exposed to soils or groundwater, cement suitably resistant to sulphate attack shall be used for the entire structure.

h) Cement to be used to resist sulphate attack shall be one of the following:

i) sulphate-resisting portland cement complying with MS 1037.

ii) portland pulverised fuel ash cement complying with MS 1227.

iii) ground granulated blast furnace slag complying with MS 1387.

iv) high silica content portland cementv) supersuphated cement complying with BS 4248.

i) Aggregates shall comply with MS 29 and shall be coarse aggregate of 20 mm nominal maximum size.

j) Approval for admixtures shall be obtained prior to inclusion in the concrete mix. All admixtures shall comply with MS 822.

k) Steel reinforcement shall comply with:

i) MS 144 for cold reduced mild steel wire.

ii) MS 145 for steel fabric.

iii) MS 146 for hot rolled steel bars.

l) Welding of steel reinforcement shall be in accordance with BS 7123.

m) Waterstops for sealing joints in concrete shall comply with MS 1292.

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4.6.2 Steel

I) Structural steel

a) Structural steel sections shall comply with BS 4 or otherwise with:

i) En 10162 for cold rolled steel sections.

ii) En 10210 for hot rolled steel sections.

iii) En 10025 for weldable structural steel.

iv) En 10296, En 10297 and En 10305 for steel tube.

b) The use of structural steel in building shall be in accordance with MS 416.

c) Minor structural steelwork shall be Grade 43A complying with En 10025. All other steelwork shall be of appropriate grade, as determined using MS 416 and other appropriate standards. These shall be determined by a qualified structural engineer.

II) Coating for steel

a) Steelwork that may be in contact with sewage through immersion, splash or spray, or that is over tanks containing sewage, shall be protected against corrosion using one of the following coating systems:

i) high build tar epoxy system complying with AS 3750.2 and applied in two or more coats to give a total dry film thickness of not less than 200 µm.

ii) high build micaceous iron oxide pigmented epoxy system complying with AS 3750.12 and applied in two or more coats to give a total dry film thickness of not less 200 µm.

iii) hot dip galvanised coating of 140 µm nominal thickness in accordance with MS 740.

iv) sealed sprayed zinc coating of 150 µm nominal thickness in accordance with En ISo 2063.

b) other coatings providing 10 to 20 years service, before first maintenance, as selected using Table 3 Part 8 of BS 5493 shall be considered for approval by the Commission. Steelwork that is exposed to the external atmosphere, except severe marine atmospheres, shall be protected against corrosion using one of the following coating systems:



i) a prime coat of a two pack polyamide cured epoxy zinc phosphate of dry film thickness 60 to 80 µm with a finishing coat of a high build micaceous iron oxide chlorinated rubber paint, spray applied to a dry film thickness of 60 to no more than 80 µm.

ii) hot dip galvanised coating of 85 µm nominal thickness, in accordance with MS 740.

iii) sealed sprayed zinc coating of 150 µm nominal thickness, in accordance with En ISo 2063.

c) Steel substrates shall be prepared before application of coatings, in accordance with BS 7079.

d) other corrosion protection coating systems for steelwork shall be determined using BS 5493 or AS 2312 for tropical atmospheres so as to provide 20 or more years to first maintenance.

e) unprotected steelwork in contact with sewage shall be stainless steel grade 316S31 complying with En 10088: Part 1 and 3 or En 10029 and En ISo 9445.

f) Successive coatings of the one component shall be tinted a different colour to facilitate overcoating and inspection.

g) All coatings shall be applied strictly in accordance with the coating manufacturer’s printed instructions.

h) Bolts, nuts, screws and other fasteners shall have either:

i) hot dip galvanised, in accordance with MS 739

ii) sherardized zinc coating, in accordance with BS 4921

iii) electro plating

i) Washers and other small components shall have either:

i) hot dip galvanised, in accordance with MS 740

ii) a sherardized zinc coating, in accordance with BS 4921

j) nuts, bolts, screws and washers in contact with sewage shall be stainless steel of Grade 316S31 steel complying with En 10088: Part 1 and 3 or En 10029 and En ISo 9445.

k) Fasteners of incompatible material to the component being fastened shall have suitable isolating washers and sleeves.

III) Marine and Corrosive Environment

a) All areas within 5 km from the coast line or salt water bodies shall be classified as marine environment. Sewerage facilities in marine and corrosive environment e.g. where the atmosphere

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or soil contains high levels of chloride, sulphates and corrosive chemical elements or compounds shall be adequately designed to withstand the corrosive actions of the chemicals prevalent in the environment. necessary protections shall be provided against all corrosive actions of the environment.

b) Design requirement for facilities in marine and corrosive environment shall include:

i) Two coats of sodium silicate shall be applied to all external surfaces of concrete structures.

ii) Concrete shall be resistant to all chemical attacks and be designed in accordance with BS 8110 Part 1: 1997.

c) Exposed metal shall be of corrosion resistant and of marine grade. Proper smooth surface finishing shall be provided for the metal. unprotected metals acceptable for use are as follows:

i) SS316L

ii) Aluminium alloy

iii) Materials suitable for use in corrosive environment acceptable by the Commission

d) All structural steelwork shall be thoroughly descaled to BS 7079 second quality and shall be painted with 2 coats of two pack epoxy based red lead primer before leaving the manufacturer’s works. In addition, all structural steelwork shall be provided with protective paint for chloride, sulphate or the prevailing chemicals in the site after installation.

e) Cathodic protection shall be provided for all load bearing steel structures in marine environment for a minimum life of 50 years.

4.6.3 Fibre Reinforced Plastic (FRP)

only FRP products approved by the Commission shall be used and FRP products shall not be used for access purposes.

FRP tanks, vessels and appurtenances for sewage treatment processes shall be designed in accordance with BS 4994 and En 13923. The thickness of the structural section of the FRP tank wall shall not be less than 5 mm and shall be at least of wall thickness as given in ASTM D 4097.

All other FRP products shall meet the requirements of ASTM C 582 for FRP laminates.



notwithstanding any other requirements in standards, all FRP products, including FRP tanks and vessels for sewage treatment processes, shall conform to the following material requirements:

a) FRP properties shall be as determined by design to standards mentioned in this Section and other relevant standards, but shall not be less than the following values:

− Tensile strength - 80 MPa

− Tensile modulus - 7000 MPa

− Flexural strength - 140 MPa

− Flexural modulus - 6000 MPa

− Water absorption - ≤ 0.75 %

− Barcol hardness - 40

− operating temperature - -40oC to +50oC

− Specific gravity - ≥ 1.5

− Fire rating – ASTM E84, < 25s or Class 1 BS476

b) unsaturated polyester resins shall be used but shall only be isophthallic, bisphenol A fumurate or terephthalic polyester resins meeting the requirements of Type B or C of BS 3532.

c) All surfaces shall have a resin rich layer, gel coat. Surfaces in contact with sewage, water or any moisture shall comprise of a resin rich layer at least 1 mm thick. All other surfaces shall comprise of a resin rich layer at least 0.25 mm thick. up to 10% by mass of corrosion resistant glass fibres, (that is, C-glass or E-CR glass), polyester fibres or acrylic fibres may be used in the surface layer.

d) A barrier layer shall be provided behind the surface layer and shall be at least 1.5 mm thick. The barrier layer shall comprise of 70 to 80 % by weight resin with the remainder by weight being E glass or E-CR glass.

e) The structural layer shall comprise resin impregnated layers of E glass or E-CR glass and shall comprise at least 25 % E glass or E-CR glass. Aggregate and filler may be included.

f) E glass and E-CR glass shall conform to the requirements of:i) En 14020 for glass rovings.ii) En 14118 for chopped strand mat.iii) BS 3396 for woven fabric.iv) BS 3749 for woven roving fabric.

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g) Glass fibres shall have a surface treatment compatible with the manufacturing process to ensure bonding to the resin.

h) Aggregates shall only be used in FRP structural layers and external layers. Aggregates shall be clean, washed, high grade silica sand containing not less than 95 % silica. Aggregates shall be of a size not greater than 20 % of the thickness of the FRP structural layer with a particle size not less than 0.05 mm and not greater than 5 mm.

i) Fillers shall only be used as a resin extender and shall comprise of clean inert material, for example, silica, with particle size less than 0.05 mm.

j) Surfaces exposed to sunlight shall incorporate provisions to minimise ultraviolet degradation, such as, ultraviolet inhibitors, screening agents or pigment in the outer resin rich layer.

k) Pigments and dyes shall not normally be required, but where required by the Commission, shall be of a type and colour specified by the Commission.

l) FRP water tanks shall comply with the above requirements and requirements in:

i) MS 1241: 1991 where not constructed of FRP panels.

ii) MS 1390: 1995 where constructed of FRP panels.

m) All design of package plants using FRP materials shall take into account for the buoyancy effects. This effect is of concern during high ground water conditions and emptying of the tank content during desludging works.

n) Anchor strap shall be at least stainless steel grade 304.

4.6.4 Aluminium

a) Aluminium is found primarily as the ore bauxite and is remarkable for its resistance to corrosion (due to the phenomenon of passivation) and its light weight. Structural components made from aluminium and its alloys are very important in which light weight, durability, and strength are needed.

b) Wrought aluminium and aluminium alloys shall comply with:i) BS 1161 for structural purposes. ii) En 485 for sheet plate and strip. iii) En 754 for drawn tube.iv) En 755 for bars, extruded round tubes and sections.



v) En 1676 for ingots and castings.vi) BS 4868 for profiled sheet.

c) Anodic oxidation coating on aluminium shall be in accordance with En 12373.

d) Requirements for structural design, materials, workmanship and protection of aluminium shall be in accordance with BS 8118

4.6.5 HDPE (High Density Polyethylene)

high-density polyethylene (hDPE) is the high density version of PE plastic. Its molecules have an extremely long carbon backbone with no side groups. As a result, these molecules align into more compact arrangements, accounting for the higher density of hDPE. hDPE is stiffer, stronger, and less translucent than low-density polyethylene. hDPE is lighter than water, and can be moulded, machined and joined together using welding.

high-density polyethylene shall comply to the following physical properties:-

− Tensile Strength 0.20 – 0.40 n/mm2

− notched Impact Strength no break Kj/m2

− Thermal Coefficient of expansion 100 – 220 x 10-6

− Max Cont use Temp 650C

− Density 0.944 – 0.965g/cm3

− Minimum Require Strength 8.0 MPa

Volume 4



78

Section 5

Requirements for IndividualTreatment Processes

Volume 4

Requirements for Individual Treatment Processes


80



5.1 Introduction

All new applications for sewage treatment plant approval shall follow the design requirements as stipulated in this section. These requirements have been formulated as a gradual change in sewage treatment methods for Malaysia prior to enforcement of ultimate requirements as stipulated in Sections 3 and 4 of this volume.

Design requirements for each stage of the sewage treatment process, as shown in Figure 5.1 are given in this section.

Figure 5.2 gives an overview of the typical flow diagram and elements of a sewage treatment plant. Figure 5.2 also shows how one facility is closely related to another and thus has an impact upon the overall design.

Sewage treatment plants must be designed to produce an effluent quality that conforms to either Standard A or Standard B or any other special requirements under the provisions of the Environmental Quality Act.

The major indices are those of BOD5, Suspended Solids, COD, Oil & Grease, Ammoniacal Nitrogen, Nitrate Nitrogen and Total Phosphorus.

The requirement to comply with absolute standards, where no failures are permitted by law, means that new sewage treatment plants must be designed to produce average effluent qualities well below those permitted by the Standard figures. Design values for final effluent shall be used in the design of new treatment works are given in Table 3.2. These design effluent levels serve as the basis for the design requirement of each unit process given in the following sub sections.

General ventilation systems shall be provided in compliance to the OSHA. The potential for odour generation, its impact and treatment, shall be considered in all aspects of design. Odour treatment equipment shall be selected that such odours be reduced to the lowest possible level and in compliance to the EQA.

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82

Figure 5.1 Typical Treatment Process Flow Chart

Requirements for Stages of Sewage Treatment

egareweS naisyalaM 4 emuloV 07 senilediuG yrtsudnI

Figure 5.1 Typical Treat ment Process Flow Chart

Pump Station

Secondary Screen

Treatment Processes

Design Requirements

Function

Section 5.21 M

Section 5.32 M/O

Section 5.43 M

Section 5.54 M

5 M/O Section 5.6

Section 5.76 M/O

Section 5.87 M

Section 5.98 M

Section 5.109

M

Section 5.1110 M

Section 5.1211 M/O

Sludge Disposal

Balances and equalises �ow

Remove major polutants (BOD and SS)

Reduces potential detrimental e�ect on the environment and converts sludge to a form suitable for ultimate disposal

Separates treated e�uent and settled sludge

Destroy disease causing organisms

Measures and records �ows

Treatment Stage

Removes rocks, roots and rags

Lifts sewage and provides consistent �ow to the treatment system

Removes smaller/�ner particles from sewage

Removes sand, gravel and other inorganic materials; separates oil & grease

Removes settleable solids/materials

PrimaryScreen

Secondary Sedimentation

Disinfection

Primary Sedimentation

BiologicalTreatment

Balancing Tank

Grit/Grease Removal

Flow Meter

ThickenerStabilisation

HoldingDewatering

Pre Treatment

Primary Treatment

Secondary Treatment

Bio Solids Handling

Mandatory (M) Requirements

Optional (O)



Figure 5.2 Typical Elements and Process Flow Diagram of a Sewage Treatment Plant



Figure 5.2 Typical Elements and Process Flow Diagram of a Sewage Treatment Plant

1

Raw

Sew

age

Inle

t

Sew

age

Pum

p St

atio

n

2

Prim

ary

Scre

en

3

Seco

ndar

yS

cree

n

Bala

ncin

gTa

nk

4

5

Alte

rnat

ive

Prim

ary

Cla

rifie

r

6

A. C

onve

ntio

nal

Act

ivat

ed S

ludg

e

B.

Ext

ende

d A

erat

ion

Act

ivat

ed S

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e

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rickl

ing

Filte

rD

. RB

C

Bio

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cal S

yste

m

7

Flow

Dis

tribu

tion

Fina

l Cla

rifie

r

8D

isin

fect

ion

9

10

Flow

Met

er

Effl

uent

To

Nea

rest

R

ecei

ving

Wat

erco

urse

Ret

urn

Slud

geP

ump

Stat

ion

Mec

hani

cal S

ludg

eTh

icke

ner

Liqu

orR

etur

n

Mec

hani

cal S

ludg

eD

ewat

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g

Slu

dge

Sto

rage

Are

a

Slu

dge

Dig

este

rU

ltim

ate

Dis

posa

l

Slu

dge

Hol

ding

Tank

Slud

ge D

ryin

g Be

d

Alte

rnat

ive

Grit

/Gre

ase

Alte

rnat

e

Inci

nera

tor/D

ryer

Volume 4



84

5.2 Design of Primary Screens

5.2.1 Purpose of Primary Screens

Upon reaching the sewage treatment plant, sewage flows through the primary screening facility which is the first stage of treatment. The screens must be provided upstream of all inlet pump stations and shall be designed to protect downstream processes and equipment. The purposes of primary screens are:

a) to protect equipment from rags, wood and other debris b) to reduce interference with in-plant flow and performance

5.2.2 Inlet Chamber

Provision for inlet chamber before the primary screen channel is necessary for proper operational and maintenance. The summarised requirements for inlet chamber are as follows:

Table 5.1 Requirements for Inlet Chamber

Unit Process Requirements Notes

Inlet Chamber

MandatorySingle and dual penstocks are referring to members of penstocks required. For more than 50 000 PE, the main penstock must be motorised.

Type ≤ 20 000 PE

> 20 000 PE

> 50 000 PE

Single Yes n/a n/a

Dual n/a Yes Yes

Motorised n/a No Yes

n/a – Not applicable

a) A penstock shall be installed upstream to isolate the pump station in the event of flooding in relation to the bypass and emergency overflow.

b) For safety reasons, a double penstock system shall be provided at the inlet works of all plants with pump station above 20 000 PE.

c) The penstock spindle shall extend to pump station ground level and shall be suitably positioned to allow unrestricted operation of the penstock.



Figure 5.3 Typical Details of Double Penstock

IL1:2

INLETCHAMBER

CLEAR SPACINGMANUAL FINE SCREEN

OVERFLOW PIPEDISCHARGETO DRAIN

SECOND PENSTOCK

PRIMARYSCREEN

CHAMBER

FIRST PENSTOCK

450mm

5.2.3 Design Requirements for Primary Screens

Table 5.2 Provision of Primary Screens

RequirementsNumbers of Primary Screen

≤ 5000 PE > 5000 PE

DutyManual 1 Unit -

Mechanical - 1 Unit

Standby Manual - -

Mechanical - 1 Unit

By Pass 1 Unit 1 Unit

Volume 4



86

Table 5.3 Design Parameters for Primary Screens

Description UnitDesign Criteria

Manually Raked

Mechanically Raked#

Maximum clear spacing mm 25 25

Slope to the vertical30o – 45o 15o – 45o

Maximum approach velocity at the feed channel

m/s 1.0 1.0

Maximum flow through velocity at the screen face

m/s 1.0 1.0

Minimum freeboard mm 150* 150

Estimated volume of screenings per volume of sewage

m3 / 106 m3 30 See Figure 5.4

Screenings skip storage capacity day 7 7

Minimum channel width mm 500 500

Minimum channel depth mm 500 500

RC Staircase with riser detail 1 unit Anti-skid and non-corrosive

Anti-skid and non-corrosive

Notes:* Designer shall ensure that with 50% of blockage at the face of screen, sufficient

freeboard is provided to prevent the approach channel from overflowing

# Washing and dewatering of screenings shall be provided.

5.2.4 General Requirements

All plants must include:

a) An emergency manual bypass screen. In the event of system failure and/or power outages, the flow shall be automatically directed to the bypass. It shall also be able to cope with maximum flow.

b) Hand railings, kick plates, standing platforms and other safety features to improve maintenance

Screen chambers must be of open channel construction with proper ventilation. Forced ventilation must be used if chambers are enclosed.



Screens must be designed to withstand the flushing velocity. In the event of the manual bypass screen being blocked, sewage must be able to flow over the top of the screen without causing excessive backup flooding or overflows.

Chambers design must have taken into consideration necessary health and safety aspects. The chamber must also be hydraulically efficient to prevent the settlement of solids in the chamber.

Macerators and communitors as replacements for primary screens are generally not recommended. It may be considered if the consultant is able to provide good engineering reasons for its application.

Reinforced concrete staircase with proper handrailing must be provided to access screen chambers.

Shaftless screw conveyors and belt conveyors may be used where required. The screw conveyor shall be equipped with easy to remove covers. The frame and support of screw conveyor shall be of minimum stainless steel Grade 304 while the screw shall be of high tensile steel. The belt conveyors shall be of heavy duty reinforced rubber belts on a protected mild steel frame. Conveyors shall normally be installed on a very slight grade to allow drainage, with foul water returned to the inlet channel.

All screenings raked from mechanical screen shall be dropped into a skip.

A proper standpipe shall be provided and located within 3 m to the screen chamber.

Figure 5.5 and 5.6 illustrate typical arrangement of screen chambers of various depths.

Refer also to relevant clause of MS 1228 for more details.

Volume 4



88

Figure 5.4 Quantities of Screenings Collected From Primary Screens



Figure 5.4 Quantities of Screenings Collected From Primary Screens

5432 610

80

100

60

40

20

0

Scre

enin

gs, m

/ 1

0 m

of

Sew

age

36

3

Opening Between Bars, cm

Average

Maximum



Figure 5.5 Typical Drawing of Screen Chamber based on depth (<5 m for different PE)



Figure 5.5 Typical Drawing of Screen Chamber based on depth (<5m for di�erent PE)

INCO

MIN

G S

EWER

RAM

P D

OW

N

WP

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A-A

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OW

N

WP

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CHA

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RD

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E ≤

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0)

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R'S

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INCO

MIN

G S

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RAM

P D

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N

WP

GRA

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G

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G S

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A-A

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00)

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HA

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P LO

G

INCO

MIN

G S

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< 5m

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R'S

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< 5m

TO E

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R'S

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COLL

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ON

BIN

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STA

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SE

HA

ND

RAILPE

NST

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HA

ND

RAIL

STO

P LO

G

INCO

MIN

G S

EWER

HA

ND

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STO

P LO

G

INCO

MIN

G S

EWER

S.S

PERF

ORA

TED

TRO

UG

H

< 5m

TO E

NG

R'S

DET

AIL

Volume 4



90



R.C

PERF

ORA

TED

SLA

B

SCRE

ENIN

GS

COLL

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ON

BIN

CAT

LAD

DER

OPE

NIN

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P LO

G

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MIN

G S

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R.C

STA

IRCA

SE

TO E

NG

R'S

DET

AIL

HA

ND

RAIL

HA

ND

RAIL

PEN

STO

CK

S.S

PERF

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TR

OU

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> 5m

SECT

ION

A-A

RAM

P D

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N

R.C

STA

IRCA

SE T

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ENG

R'S

DET

AIL

CHA

IN G

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RDPE

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INCO

MIN

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M.S

GRA

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G C

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RAM

P D

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UA

RDPE

NST

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MIN

G S

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WP

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W(P

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DER

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MIN

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A-A

RAM

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AIL

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A-A

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R'S

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CHA

IN G

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CHA

IN G

UA

RDPE

NST

OCK

INCO

MIN

G S

EWER

INCO

MIN

G S

EWER

WP

PLAN

VIE

W

DN

< 5m

WP

PLAN

VIE

W

DN

< 5m

R.C

PERF

ORA

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SLA

B

SCRE

ENIN

GS

COLL

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ON

BIN

CAT

LAD

DER

OPE

NIN

GS

R.C

PERF

ORA

TED

SLA

B

SCRE

ENIN

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COLL

ECTI

ON

BIN

CAT

LAD

DER

OPE

NIN

GS

STO

P LO

G

INCO

MIN

G S

EWER

R.C

STA

IRCA

SE

TO E

NG

R'S

DET

AIL

HA

ND

RAIL

HA

ND

RAIL

PEN

STO

CK

MEC

HA

NIC

AL

COA

RSE

SCRE

EN

STO

P LO

G

INCO

MIN

G S

EWER

R.C

STA

IRCA

SE

TO E

NG

R'S

DET

AIL

HA

ND

RAIL

HA

ND

RAIL

PEN

STO

CK

MEC

HA

NIC

AL

COA

RSE

SCRE

EN

SECT

ION

A-A

Figure 5.6 Typical Drawing of Screen Chamber based on Depth. (>5 m for different PE)



5.3 Design of Pump Stations

5.3.1 Purpose of Pump Stations

Inlet pump stations must be preceded by primary screens to protect the pumps from being damaged or clogged. The inlet pumps of the treatment works must be capable of handling raw unscreened sewage. Water pumps must not be used as they are not designed to cope with matters that may be found in sewage and the variability and quantity of sewage flow. The purposes of pump stations are:

a) To lift sewage to a higher point for treatment

b) To provide consistent inlet flows to the treatment system

c) To prevent overflow of raw sewage

5.3.2 Design Requirements

(I) Structural Requirements

a) Substructure shall be constructed with reinforced concrete using cement resistant to chemical attack, aggressive soils and groundwater.

b) Safe and suitable access to the wells shall be provided.

c) If cement used is not resistant to the chemical attack, internal walls shall be made resistant to sulphide corrosion by coating with high alumina cement or approved equivalent coating.

d) A controlled overflow from the last manhole upstream of the pump installation shall be provided to allow emergency maintenance works.

e) Access shall be provided at all locations where operation and maintenance works take place.

f) Static screen shall be provided at specific locations where it needs to protect downstream unit processes.

g) Access covers shall be hinged with a lifting weight not exceeding 16 kg.

Volume 4



92

II) Ventilation Requirements

a) Ventilation shall be provided for all hazardous zones of the pump station.

b) Below ground pits shall have mechanical ventilation.c) Separate ventilation shall be provided for wet wells and dry

wells.d) Lighting systems shall be interconnected with ventilation.e) Permanent ventilation rate and air changes shall comply with

Section 6 of this Guidelines.

III) Odour Control Requirements

a) Isolate odorous gases from general ventilation by containing identified odour generating sources with a separate local exhaust system.

b) Containment of the odour sources shall be by installing lightweight and corrosion resistant covers/enclosures designed for practical operation and maintenance works.

c) Local exhaust rates for containment shall be designed to provide a negative pressure preventing build up of toxic, corrosive or explosive gases and to include provision for process air or air displaced by changes in the level of liquid inside the covered space.

d) The odourus air in the local exhaust system shall be conveyed through well designed and balanced ductworks by a centrifugal fan to an effective odour treatment system.

e) Odour treatment equipment shall be selected such that odour is reduced to the lowest possible level and in compliance to the EQA.

f) In situation where specific gases such as hydrogen sulphide and ammonia are significantly present, provide a pre-scrubber unit upstream of the main odour treatment equipment.

g) Containment, exhaust and treatment shall be designed as an integrated package.

h) Consideration must be given to the life span of the odour control system and associated costs in operating and maintaining such a system.

IV) Wet Wells Requirements

a) Suction channels shall be designed to avoid “dead zones”, i.e., prevent solids and scum accumulation. All “dead zones” shall be chamfered.



b) Benching shall be such that to minimise deposition of solid matters on the floor or walls of wet wells. The minimum slope of benching shall be 45o to the horizontal.

c) Benching shall preferably be extended up to the pump intake.d) Minimum hopper bottom slope shall be 1.5 vertical to 1.0 horizontal.

Tapered slope shall be provided up to the suction section.e) Automatic flushing of grit and solids is recommended for plants

of PE > 2 000.f) The difference between stop and start levels shall be a maximum

of 900 mm and a minimum of 450 mm.g) The difference in level between start or stop of duty and assist

pumps shall be greater than or equal to 150 mm.h) The minimum internal width of wet well shall not less than 2m. i) Where possible, wet wells shall be open and guarded by a handrail

or open mesh grating. The grating shall be easily and safely removed.

Figure 5.7 Typical Dimensions of Wet Well

Submersible Pump Station


18 4 emuloV stnalP tnemtaerT egaweS

b) Benching shall be such that to minimise deposition of solid matters on the floor or walls of wet wells. The minimum slope of benching shall be 45o to the horizontal.

c) Benching shall preferably be extended up to the pump intake. d) Minimum hopper bottom slope shall be 1.5 vertical to 1.0 horizontal.

Tapered slope shall be provided up to the suction section. e) Automatic flushing of grit and solids is recommended for plants of

PE > 2,000. f) The difference between stop and start levels shall be a maximum of

900 mm and a minimum of 450 mm. g) The difference in level between start or stop of duty and assist

pumps shall be greater than or equal to 150 mm. h) The minimum internal width of wet well shall not less than 2m i) Where possible, wet wells shall be open and guarded by a handrail

or open mesh grating. The grating shall be easily and safely removed.

Figure 5.7 – Typical Dimensions of Wet Well

Submersible Pump Station

i

CUT OUT LEVEL

LOW LEVEL ALARM

INCOMING SEWER

Qi (I/S)

CUT IN LEVEL

STANDBY CUT IN LEVEL

HIGH LEVEL ALARM

≥15

0d

sk

D2

QO (I/S)

Note :

Q1 = Incoming flow rate

QO = Forcemain Discharge rate

D2 = Forcemain Diameter, min 100

d = Difference between stop & start level, Min 450 Max 900

s = Minimum submergence, depends on manufacturer recommendation

k = Minimum clearance between pump suction and wet-well invert

All dimension are in mm unless otherwise state

MIN 2000

D1

(ℓ/S)

(ℓ/S)

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Figure 5.8 Typical Dimensions of Dry Well Submersible Pump Station


egareweS naisyalaM 4 emuloV 28 Industry Guideline

Figure 5.8 – Typical Dimensions of Dry Well Submersible Pump Station

LOW LEVEL ALARM/EMERGENCY CUTOUT

INCOMING SEWER

Q (I/S)i


CUT OUT LEVEL

CUT IN LEVEL

HIGH LEVEL ALARM

D2 to D24

3

D1QO (l/s)

D2 150 (min)

150

D2

to D

2

2

SD

150

ALLOW ADDITIONAL DEPTHFOR SOLID HEAVY OBJECTS

Note :

Q1 = Incoming flow rate

QO = Forcemain Discharge rate

D2 = Bellmouth Diameter

D1 = Suction Diameter, Min 100

D = Difference between stop start level, Min 450 and Max 900

S = Minimum depth above pump intake to prevent vortex formation

LOW LEVEL ALARM/EMERGENCY CUTOUT

INCOMING SEWER

Q (I/S)i


HIGH LEVEL ALARM

CUT OUT LEVEL

CUT IN LEVEL

150

DS

D2

D2 T

O D

215

0

ALLOW ADDITIONAL DEPTHFOR SOLID HEAVY OBJECTS

D1 Q0 (l/S)

(V) Lighting Requirements a) Wet wells and dry wells shall be adequately lit.

b) Electrical installations shall be water proof and vapour proof or explosion proof.

c) If lights are fitted outside the well, then a spotlight system may be used to provide adequate illumination.

V) Lighting Requirements

a) Wet wells and dry-wells shall be adequately lit.

b) Electrical installations shall be waterproof and vapour proof or explosion proof.

c) If lights are fitted outside the well, then a spotlight system may be used to provide adequate illumination.



VI) Level Controls

a) Either floats or ultrasonic level controller may be used for the start-stop levels of pumps. Instrument with environmental friendly features are recommended.

b) Ultrasonic level control is recommended due to its clog-free nature.

c) Non-mercury type floats are recommended.d) Hollow tube electrodes are not acceptable.e) Level controller shall be placed where they are not affected by

the turbulence of incoming flow and where they can be safely removed.

VII) Pump Hydraulic Design

a) The submission of pump hydraulic design and performance shall include:i) System curvesii) Pump curvesiii) Operating points of pumps with respect to flow and total

dynamic head (TDH) iv) Operating characteristics such as efficiency, horsepower and

motor ratingb) Pump shall be operating within their best efficiency range at

normal operating condition.c) Pumps are to be equipped with an auto restart mechanism in the

event of power failure.d) Dry-well mounted pumps shall be equipped with auxiliary services

such as cooling and gland seal water supply.e) Pumps equipped with cutting or macerating facilities are not

acceptable.f) Guide rail, lifting device and other wet well fittings must be

fabricated of stainless steel that is corrosion resistant. The use of hot dip galvanised iron is not recommended.

g) Horizontal installation of pumps is not allowed. All pumps shall be installed vertical, unless the Consultant is able to provide good engineering reasons for horizontal installation.


a) Drainage of dry-wells and valve pits shall be provided. Drainage lines shall be equipped with back flow protection to ensure that the chamber is not flooded.

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96

b) The wet well shall not be housed with a building structure.

c) Where separate valve pits are used, the connecting pipes shall incorporate at least two flexible joints to allow for differential settlement.

d) Pipework

i) Pipe work shall be of ductile iron or cast iron with cement internal lining. Other approved material by the Commission may be used.

ii) External surface of pipework in chambers and wells shall be epoxy coated.

iii) Buried ductile iron pipe shall have polyethylene sleeving.iv) Pipe within wells and pits shall have flanged joints, while

pipe laid in the ground shall have spigot and socket joints.v) Pipe work shall be adequately supported on concrete plinths

or steel structural supports.vi) Flanges shall be located at least 150 mm away from

structures.vii) Dismantling joints such as bends shall be provided.viii) Pumping thrust shall be resisted using pipe supports inside

chambers and by mass concrete thrust blocks poured against undisturbed soil in the ground outside chambers.

ix) No welding joints are allowed.

e) Valves

i) Gate valves are preferred with rising spindles operated by a tee piece.

ii) The uses of counterweights are recommended. Tapping (12 mm BSP) shall be located upstream and downstream of check valves.

Also refer to additional requirements in relevant Clause of MS 1228.



Figure 5.9 Typical Details of Wet-well Pump Station



Figure 5.9 Typical Details of Wet-well Pump Station

PENSTOCK

PLAN VIEW

R.C STAIRCASE TO ENGR'S DETAIL

16 131415 12 11 678910 5 1234

DELIVERY PIPE

GRATING COVER

STEPS

FINE SCREEN

CLEAR SPACINGS.STEEL MANUAL

CHAMBERA

OVERFLOW

INCOMING SEWER

DISCHARGE TO DRAIN OVERFLOW PIPE

S.STEEL HANDRAIL

20191817 232221 PUMP SUMP

PRIMARY SCREEN

CHECK VALVE

EXPLOSION PROOF

FLEXIBLE COUPLINGGATE VALVE

SPOT LIGHT

A

COLLECTION BIN

STEPSGRATING COVER

INFLUENT PUMP

CONC. APRON

STAND PIPEV.C.P

MECH. COARSE SCREEN

NON-EXPLOSION SPOT LIGHT

CHAMBERPRIMARY SCREEN

SECTION A-A

IL1:2

CHAMBEROVERFLOW

MANUAL COARSE SCREEN

STOP

HAND WHEELFRP STOP LOG C/W

ALARMSTART

IL OPENING

R.C WALL TO ENGR'S DETAIL

CONC. SLAB

IL

PUMP SUMPS.S PERFORATEDTROUGH

DELIVERY PIPE

LIFTING CHAIN

GUIDERAIL

HANDRAIL

MANUAL FINE SCREEN

PIPE DISCHARGETO DRAIN

OVERFLOW

CLEAR SPACING PENSTOCKFLEXIBLE COUPLING

DELIVERY PIPEGATE VALVE

CHAIN GUARDCHECK VALVE

MECH. COARSE SCREENCARRIERLIFTING I-BEAM C/W

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98

Figure 5.10 Typical Details of Dry-well Pump Station


86 Volume 4 Malaysian Sewerage Industry Guideline

Figure 5.10 Typical Details of Dry-well Pump Station

BLOCK3 LAYER CONC. VENTILATION

PERFORATED SLAB

DOOR

LIGHTNING ARRESTORCOPPER TYPE

CARRIERLIFTING I-BEAM C/W

WINDOW

GATE VALVE

CHECK VALVE

DRY PIT PUMPSDEWATERING PUMP

SCREENINGS COLLECTION BIN

CHEQUER PLATE

CAT LADDER

WET WELL DRY WELL

(FLOAT SWITCH)

OPENINGS

STOP LOG

INCOMING SEWER

R.C STAIRCASE TO ENGR'S DETAIL

HANDRAIL

HANDRAIL

PENSTOCK

MECHANICAL COARSE SCREEN TO NEAREST SUMPRAIN WATER DOWN PIPE

R.C GUTTER TO ENGR'S DETAIL

BRICKWALL C/W CEMENT PLASTER ON BOTH SIDES

1st. STANDBY PUMP START ALARM

2nd. STANDBY PUMP START

SUMP BWL

ALL PUMP STOP

1st.. DUTY PUMP START

2nd. DUTY PUMP START

RAMP DOWN

DN

G.I

CH

AIN

GU

ARD

.

PLAN VIEW

LOUVRES WINDOWADJUSTABLE GLASS

DOOR

DRY PIT PUMPS

R.C STAIRCASE TO ENGR'S DETAIL124 378 6 5101112 913

SPOT LIGHTCHEQUER PLATE

BRICKWALL C/W CEMENTPLASTER ON BOTH SIDES

AIR EXTRACTOR FAN

3 LAYER CONC. VENTILATION BLOCK

CHECK VALVE.

R.C STAIRCASE TO ENGR'S DETAIL.

BLOCK AT TOP AND BOTTOM LEVELCONCRETE VENTILATION

EXTRACTOR FAN

CONC. THRUST BLOCK.

654321

7

CHAIN GUARD.

181920212223

17

DN

CONC. THRUST BLOCK.

A

GATE VALVE.

1011

9816

131415

12

G.I CHAIN GUARDPENSTOCK

20191714 15 16 18 21

A

NCOMING SEWER

GRATING COVER

FORCEMAIN

3 LAYER CONC. VENTILATIONBLOCK AT TOP AND BOTTOM LEVELLIQUID RETURN FROM OTHER UNIT PROCESSESDRAIN

CONC. APRON LAID TO FALL

MECHANICAL COARSE SCREEN

OVERFLOW CHAMBER

WP

OVERFLOW PIPE DISCHARGETO MONSOON DRAIN

AT TOP AND BOTTOMLEVEL

SECTION VIEW



Table 5.4 Recommended Design Parameters for Inlet Pump Stations

≤ 1000 Design Parameters

Description Unit PE ≤1,000 1,000 < PE ≤ 5,000

Type of station Wet well Wet well Number of pumps (all identical and work sequentially)

2 1 duty,

1 standby (100 % standby)

2 1 duty,

1 stand-by (100 % standby)

Pumps design flow Each at Qpeak

Each at Qpeak

Maximum retention time at Qave

min 30 30

Min pass through openings mm 75 75Minimum suction and discharge openings mm 100 100Pumping cycle (average flow conditions)

start/ hour

6 min 15 max

6 min 15 max

Lifting device* Lifting davit Lifting beam and block

Design ParametersDescription Unit 5,000 < PE ≤ 20 000 PE > 20,000Type of station Wet well or dry-well

up to 10,000 PE

10,000 PE above – wet well and dry-well

Wet well and dry well

Number of pumps

(all identical and work sequentially)

4 (2 sets) 1 duty, 1 assist,

per set (100 % standby)

6 (3 sets) 1 duty, 1 assist,

per set (50 % standby)

Pumps design flow Each at 0.5 Qpeak Each at 0.25 Qpeak

Maximum retention time at Qave

min 30 30

Min pass through openings mm 75 75

Minimum suction and discharge openings

mm 100 100

Pumping cycle (average flow conditions)

start/ hour

6 min 15 max

6 - 15

Lifting device* Mechanical and block Mechanical

Note: * Motorised hoists shall be provided when the lifting weight exceeds 100 kg

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5.4 Design of Secondary Screens

5.4.1 Purpose of Secondary Screens

After the inlet pump station, further screening is required to reduce the remaining floating matter and finer particles in the sewage that will disrupt the treatment process downstream. The purposes of secondary screens are:

a) to remove material such as plastic, paper, cloth and other particles that may cause problems to the treatment process downstream.

b) to minimise blockages in sludge handling and treatment facilities.


Plants of all sizes must be installed with secondary screens. The channel shall be designed for Qpeak or pump flow whichever is greater. Approach channel shall be design to ensure good contribution of velocity

A minimum of two screens are required for duty and standby. Facility for a screened bypass must be provided in the event of clogging. Where mechanically cleaned screening devices are installed auxiliary manually cleaned screen shall be provided.

Table 5.5 Provision Requirement of Secondary Screens

RequirementsNumbers of Secondary Screen

≤5000 PE >5000 PE

DutyManual 1 Unit -Mechanical - 1 Unit

StandbyManual - -Mechanical - 1 Unit

Bypass Screen 1 Unit 1 Unit



Table 5.6 Design Parameters for Secondary Screens


Manually Raked

Mechanically Raked #

Maximum clear spacing mm 12 12Slope to the vertical 30o – 45o 15o – 45o

Maximum approach velocity at the feed channel

m/s 1.0 1.0

Maximum flow through velocity at the screen face

m/s 1.0 1.0

Minimum freeboard mm 150* 150

Estimated volume of screenings per volume of sewage

m3 / 106 m3 See Figure 5.4

Screenings skip storage capacity day 7 7Minimum channel width mm 500 500Minimum channel depth mm 500 500RC Staircase with riser detail 1 unit Anti-skid and

non-corrosiveAnti-skid and non-corrosive

Notes:* Designer shall ensure that with 50% of blockage at the face of screen, sufficient

freeboard is provided to prevent the approach channel from overflowing

# Washing and dewatering of screenings shall be provided.

5.5 Design of Grit and Grease Chambers

5.5.1 Purposes of Grit and Grease Chambers

This unit process is important to minimise problems associated with grit and grease. Grit creates problems to pumps and also sludge digestion and dewatering facilities. Grease creates problems at the clarifier and is carried over in the final effluent.

In grit removal system, grit or discrete particles that have subsiding velocities or specific gravities substantially greater than those of organic putrescible solids, e.g. eggshells, sands, gravel are removed by gravitate settlement or centrifugal separation. Same principle apply to oil and grease removal system, where free oil and grease globules lighter than water rise through the liquid and skimmed from the top surface.

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102

The particles must be removed at an early stage of the process because:

a) the grit particles cannot be broken down by any biological treatment.

b) the grit particles are abrasive and wear down equipment.

c) the biological treatment in sewage treatment works is not designed to degrade grease.


A manual bypass shall be provided. In case of grit removal system failure and/or power outages, the flow shall be automatically directed to the bypass.

Where mechanical grit separator is used, they shall be installed at an angle of at least 10° to allow drainage and foul water to be returned to the inlet channel.

Where manual systems are used, allow for safe and easy access to remove grit to a storage bin.

If pump systems are used, the suction pipe shall be short and straight. Tees and short radius bends shall be avoided, if at all possible. Flanges at strategic locations shall be provided so that they can be dismantled to remove any blockages.

The mechanical oil and grease skimming device shall be designed to minimise the water being remove while skimming the oil and grease.

Sand pit may be used for further dewatering of the grease removed before ultimate disposal. The drainage from the sand pit shall be returned to the inlet channel for further treatment.



Table 5.7 Provision Requirement of Grit and Grease Removal System

RequirementsNumber of Unit Processes

≤ 5000 PE > 5000 PE

i) Grit Removal SystemDuty Manual 1 Unit @ design flow -

Mechanical

-

-1 Unit @ design flow (up to 10 000 PE)

-2 unit @ 50% design flow each ( >10 000 PE)

Standby Manual 1 Unit @ design flow -Mechanical - -

Bypass - Yesii) Grease Removal SystemDuty Manual 1 Unit -

Mechanical

-

-1 Unit @ design flow (up to 10 000 PE)

-2 unit @ 50% design flow each ( >1000 PE)

Standby Manual 1 Unit @ design flow -Mechanical - -

Bypass - Yes

5.5.3 Design Criteria

Design criteria are given in Tables 5.8 and 5.9.

Table 5.8 Design Parameters for Grease Chambers


PE ≤ 5000* > 5000PE > 5000PEGrease removal - Simple manual Manual interceptor Mechanical

Chamber type - Rectangular Baffled tank Aerated type

Minimum detention time (Qpeak)

min 3 3 3

Grit and grease storage period before off-site disposal

day 30 7 7

Note:* Combined grit & grease chamber is allowed. If combined, then total detention

time shall comply to 6 minutes at Qpeak.

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Table 5.9 Design Parameters for Grit Chambers


PE ≤ 5000* >5000PE >5000PE

Grit removal - Manual (tanker)

Mechanical Mechanical

Chamber type - Horizontal flow (2 units required for

duty and standby during

cleaning) vortex also acceptable

Square, rotary or vortex type simple

mechanised grit chamber

Aerated

Minimum detention time at Qpeak

minute 3 3 3

Maximum gravity flow through velocity at Qpeak

m/s 0.20 0.20 0.20

Maximum centrifugal flow through velocity

m/s n/a <1.0 <1.0

Head loss (at parshall flume) - 35% of depth -

Aeration requirement

l/s/meter length of tank

- - 10.0

Chamber dimension: Depth: Width Length: Width

- 1:2

2:1

Manufacturer’s Specification

Manufacturer’s Specification

Estimated grit quantity

m3/103 m3 of sewage 0.03 0.03 0.03

Washing and dewatering of grit - No Yes Yes

Notes:* Air lift pump for removal of grit is not acceptable.* Water depth in tank to be controlled by weir outlet.



5.6 Design of Balancing Tanks

Balancing tanks are mandatory for all treatment processes that are not designed at peak flow. The tanks are effective means of equalising sewage flow. For extended aeration plants that are designed with a retention time of more than 18 hours and clarifiers designed at peak flow, the use of balancing tanks is not required.

5.6.1 Purposes of Balancing Tanks

The purposes of balancing tanks are to:

a) prevent flow variations entering secondary treatment processes.

b) reduce hydraulic loading into secondary treatment processes.

c) reduce potential overflows that may cause health hazard and pollution.


The design requirements for balancing tanks are:

a) All balancing tanks must be completely aerated and mixed.

b) Flow control shall be by a non-mechanical constant flow device, such as an orifice, in order to avoid double pumping.

c) Allowance must be made for an emergency overflow.

d) Bypass and drain down facilities as well as suitable access for cleaning shall be provided.

e) A dead water depth of 0.6 - 1.0 m is normally required.

f) For plants with PE > 10 000, where balancing tank is used, minimum one (1) unit of balancing tank shall be provided. The design flow of the upstream and downstream unit processes are recommended as follow:

i) Where no balancing tanks is provided, design flow of unit process at Upstream = Peak/pumped flow Downstream = Peak/pumped flow

ii) Where balancing tank is provided, design flow of unit process at Upstream = Peak/pumped flow Downstream = Average flow

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Table 5.10 Design Parameters for Balancing Tanks

Description Unit Design CriteriaVolume of tanks m3 1.5 hr detention at Qpeak

Mixing power requirements

W/m3 of sewage 5 at TWL

Aeration m3 air/hour/m3 sewage

1 m3 of air supply for every m3 of sewage stored per hour at TWL

Overflow bypass to downstream unit requirement - Yes

5.7 Design of Primary Sedimentation Stage

At primary sedimentation stage, the velocity of sewage is reduced to subside settleable suspended organic matters in the sewage. The settled matter is known as primary sludge.

5.7.1 Purposes

The purposes of primary sedimentation are:

a) To remove maximum amount of pollutants such as settleable solids quickly and economically.

b) To separate sewage into sludge and settled sewage, which by being treated separately are normally dealt with more efficiently and economically.

c) When used as a preliminary step for further treatment, the main function of primary sedimentation tank is to reduce the organic loadings on the secondary treatment units and is a essential component of secondary sewage treatment.


The design requirements of primary sedimentation include the followings:

a) Provide sufficient time for maximum settling under quiescent conditions. Therefore, design factors require careful consideration include: overflow rate, detention period, weir-loading rate, shape and dimensions of the basin, inlet and outlet structures, and sludge removal system.

b) Tanks can either be rectangular, circular or upward flow (square).



c) Provisions for the removal of sludge on a daily basis.

d) Holding tanks for wasted sludge must be provided.

e) V-notch weirs with baffle shall be provided at the outlet. Weirs shall be adjustable with notches 100 mm deep. Typical variation in water level shall be no more than 50 mm under all conditions.

f) Multiple hopper are not permitted.

g) Scum skimming shall be provided to remove both floating materials and scum. These materials can be either discharged to biosolid holding tank or sand drying bed. They shall not be returned to the preliminary treatment units.

h) Flow distribution channel/ chamber shall be provided for flow isolation or equal flow distribution.

i) Rectangular tank

i) Sludge hopper shall have side slopes of 60° or more from horizontal with the sludge pump located in a pit at hopper invert level. The length of suction pipe shall be minimised. Provision for withdrawal pipe from the tanks shall be provided.

ii) The capacity of hopper shall be equivalent to 2 hours detention time at Qpeak.

iii) Additional water depth of minimum 400 mm should be provided above the hopper in the vertical side-wall section between the top of the hopper and the top water level. The side-wall height should not be less than 400 mm.

iv) Equalise flow distribution across the inlet of the tank shall be achieved using a multi-port wall and baffles.

j) Circular Tank

i) Circular tanks shall be no more than 50 m in diameter and minimum water depth shall be 3.0 m.

ii) Circular tanks with more than 30 m diameter shall be provided with perimeter walkway for cleaning the weir and shall have appropriate drive system.

(k) The floor slab of the sedimentation tank shall be of reinforced concrete type construct to gradient to enhance the sludge scraping effectiveness.

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Table 5.11 Design Parameters for Primary Sedimentation

Description Unit Design CriteriaSedimentation followed by secondary treatmentDetention time at Qpeak hr 2

Surface overflow rate at Qpeak

- circular (maximum)

- rectangular (maximum)

m3/m2/d

m3/m2/d

45

45Weir loading at Qpeak m3/m/d 150

Upward flow rate at Qpeak m/hr 1.2 - 2.0

Sizing of rectangular tanksLength : Width > 3:1Min water depth m 2.5 Width : Depth 1 : 1 to 2.5 : 1Sizing of circular tanksMin. side water depth m > 3.0Floor slope wall 1:12

5.8 Design of Biological Treatment Stage

5.8.1 Introduction

Biological treatment is the heart of the sewage treatment process. It is the processes where the dissolved and non- settleable organic material remaining in the sewage are removed by living organisms.

For reasons of long term whole life economics, ease of operation and maintenance, consistent effluent standards and standardisation, the following types of biological treatment processes are recommended for use in Malaysia.

Suspended Growth System

a) Conventional Activated Sludge (CAS) System

b) Extended Aeration (EA)/Oxidation Ditch (OD) System

c) Sequencing Batch Reactor (SBR)/Intermittent Decant Extended Aeration (IDEA)



Attached Growth Systema) Rotating Biological Contactor (RBC) Systemb) Trickling Filter (TF) Systemc) Hybrid System/Combination Multistage Design

All plants must be strictly designed to meet DOE Standard A/Standard B requirements including, nitrification and denitrification to reduce ammonia and total nitrogen removal level that ensure compliance with the requirement stipulated in Section 3 earlier. Total phosphorus removal must also be taken into account for plants where treated effluent is to be discharged into stagnant water bodies.

Mass balance calculation must be computed and submitted for all biological treatment system and other unit processes proposed for the STP.

5.8.2 Conventional Activated Sludge System (CAS)

5.8.2.1 General Description

The Conventional Activated Sludge process is one of the many versions of the activated sludge process. The activated sludge process is most suitably used where land is limited and expensive, and where large volumes must be treated economically, without creating nuisance to neighbours.

The process involves the production of activated mass of microorganisms capable of stabilising sewage aerobically. This is achieved by introducing organic waste, produced from pre-treatment and primary treatment facilities, into reactors where suspended aerobic bacterial culture oxidises the organic matter into stable matters. These active bacteria cultures are commonly known as activated sludge. During the process, new bacteria cell are also produced.

5.8.2.2 Design Requirements for CAS

For the design of Conventional Activated Sludge system, the aeration tank shall be preceded with primary sedimentation system. An appropriate amount of the bacteria culture, known as activated sludge must be recycled to the upstream of the reactor while the remaining excess sludge must be removed at secondary sedimentation system.

All Conventional Activated Sludge system used at STPs for Class 3, Class 4 and at where requested by the Commission must be designed with anoxic zone to achieve a total nitrogen removal in order to comply with the requirements in Section 3 of this Guidelines, as well as to minimise potential rising sludge at secondary sedimentation system. The anoxic zone must be mixed without inducing dissolve oxygen.

Sludge treatment and dewatering must be available on-site to handle the large quantity of unstable sludge generated.

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Table 5.12 Design Parameters for Conventional/ Activated Sludge System

Description Unit Design CriteriaPrimary Sedimentation System Must be providedMinimum number of aeration tanks 2F/M ratio 0.25 - 0.50Hydraulic retention time (HRT) hrs 6 -16 (for system where

only ammonia removal is require)12 -16 (for plants require total nitrogen removal)

Oxygen requirements (for BOD and ammonia nitrogen removal)

kgO2/kg substrate 2.0

Mixed liquor suspended solids (MLSS)

mg/l 1500 -3000 Typical: 2500

Dissolved oxygen (DO) level in tank mg/l 1.0

Aeration device rating Continuous, 24 hrsSludge yield kg sludge

produced/kg BOD5 consumed

0.8 - 1.0

Sludge age # day 5 - 10Waste activated sludge, QWAS m3/d Refer to equation below †

Return activated sludge flow, QRAS m3/dCu is underflow concentration

QRAS / QINFLOW 0.75-1.0

Mixed liquor suspended solids recirculation for denitrification purpose

4 – 6 of Qavg

RAS pump rating hrs/day 24

Organic loading kg BOD5/kg MLSS 0.25 - 0.5Volumetric loading kg BOD5/m

3.d 0.3 - 0.6Minimum mixing requirement W/ m3 20



Table 5.12 Design Parameters for Conventional Activated Sludge System (continued)

Description Unit Design CriteriaTank dimensionWater depth m 3 – 5Length:Width 3:1Max width of joined tank m < 30



Table 5.12 Design Parameters for Conventional Activated Sludge System (cont.)

Description Unit Design Criteria

Tank dimension

Water depth m 3 – 5

Length:Width 3:1

Max width of joined tank m <30

# Sludge Age = total solids in aeration tank

excess sludge wasting/day + solids in effluent

†

WAS =

V MLSSQ SS

C

T

sludgeavg eff

u

Where: vT = volume of reactor (m3) MLSS = mixed liquor suspended solids (kg/m3)

sludge = sludge age (days) Qavg = average flow (m3/day) SSeff = effluent suspended solids (kg/m3) Cu = underflow concentration (kg/m3)

Refer Table D1 and D2 for aeration equipment duty / standby and also to relevant clause of MS 1228 for more details.

5.8.3 Extended Aeration System (EA)

5.8.3.1 General Discription The extended aeration process is similar to the conventional activated sludge process except that it operates in the endogenous respiration phase of the growth curve, which requires a low organic loading and long aeration time. The system produces high MLSS concentration, high RAS pumping rate and low sludge wastage. The advantage of having long hydraulic retention times is that it allows the plant to operate effectively over widely varying flow and waste loadings. Secondary clarifiers must be designed to the variations in hydraulic loadings and high MLSS concentrations associated with this process.

Refer Table D1 and D2 for aeration equipment duty/standby and also to relevant clause of MS 1228 for more details.

5.8.3 Extended Aeration System (EA)

5.8.3.1 General Discription

The Extended Aeration process is similar to the Conventional Activated sludge process except that it operates in the endogenous respiration phase of the growth curve, which requires a low organic loading and long aeration time. The system produces high MLSS concentration, high RAS pumping rate and low sludge wastage.

The advantage of having long hydraulic retention times is that it allows the plant to operate effectively over widely varying flow and waste loadings. Secondary clarifiers must be designed to the variations in hydraulic loadings and high MLSS concentrations associated with this process.

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5.8.3.2 Design Requirements for EA

EA plants shall be designed as either plug flow or completely mixed. Anoxic zone at the head of the reactor must be provided for denitrification. The anoxic zone must be mixed without inducing dissolved oxygen

For Oxidation Ditches, the minimum velocity within the channel shall be sufficient to keep the activated sludge in suspension. The minimum velocity within the channel shall not be less than 0.3 m/s. The tank configuration and aeration and mixing devices shall promote unidirectional channel flow, so that the energy used for aeration is sufficient to provide mixing in a system with a relatively long hydraulic retention time.

Table 5.13 Design Parameters for Extended Aeration

Description Unit Design CriteriaMinimum number of aeration tanks 2F/M ratio 0.05 - 0.1Hydraulic retention time (HRT) hrs 18 - 24Oxygen requirements(for BOD and ammonia nitrogen removal)

kgO2/kgsubstrate 2.0

Mixed liquor suspended solids (MLSS) mg/l 2500 - 5000 Typical: 3000

Dissolved oxygen (DO) level in tank mg/l 2.0Sludge yield kg sludge produced/kg

BOD5 consumed0.4 (at 24 hrs HRT) 0.6 (at 18 hrs HRT)

Sludge age # day > 20Waste activated sludge flow, QWAS m3/d Refer to equation †

Return activated sludge flow, QRAS m3/d

Cu is underflow concentration

RAS pump rating hours/day 24Recirculation ratio, QRAS/QINFLOW 0.5 - 1.0MLSS recycle ratio 4 – 6 times of Qavg

Volumetric loading kg BOD5/m3.d 0.1 - 0.4

Minimum mixing requirement W/m3 20Tank dimensionWater depth m 3 – 5Length:Width ratio 3:1Max width of joined tank m < 60



Refer Table D1 and D2 for aeration equipment duty/standby and also to relevant clause of MS 1228 for more details.

Figure 5.11 Fine Bubble Diffuse Air Extended Aeration System



Notes: # Sludge Age = total solids in aeration tank

excess sludge wasting/day + solids in effluen†WAS =

V MLSSQ SS

C

T

sludgeavg eff

u




Figure 5.11 – Fine Bubble Diffuse Air Extended Aeration System

RawSewage

Inlet

SewagePump Station

Screens, Grit Removal

Anoxic Zone Aeration Tank FlowDistribution

Final Clarifier

EffluentTo River

ChemicalDosing

Mechanical SludgeThickener

Liquor

Mechanical SludgeDewatering

Sludge Storage Area

Return SludgePump Station

Sludge Holding Tank

Sludge Drying Bed

Ultimate Disposal

OPTIONAL



Notes: # Sludge Age = total solids in aeration tank

excess sludge wasting/day + solids in effluen†WAS =

V MLSSQ SS

C

T

sludgeavg eff

u




Figure 5.11 – Fine Bubble Diffuse Air Extended Aeration System

RawSewage

Inlet

SewagePump Station


Anoxic Zone Aeration Tank FlowDistribution

Final Clarifier

EffluentTo River

ChemicalDosing


Liquor


Sludge Storage Area

Return SludgePump Station

Sludge Holding Tank

Sludge Drying Bed

Ultimate Disposal

OPTIONAL

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Figure 5.12 Oxidation Ditch Activated Sludge System



Figure 5.12 – Oxidation Ditch Activated Sludge System

Mechanical Rotor FlowDistribution Final Clarifier

FlowMeasurem ent


Oxidation Ditch

Return SludgePum p Station

ChemicalDosing



Sludge Storage Area

Sludge Holding Tank

Sludge Drying Bed

RawSewage

Inlet

SewagePump Station

EffluentTo River

OPTIONAL

Ultimate Disposal

5.8.4 Rotating Biological Contactors (RBC)


Rotating biological contactors use a series of rotating media for biological treatment. The rotating medium, typically made from sheets of high quality plastic, provides a surface on which organisms grow. As the media rotate, the fixed film biomass is in contact with organic pollutions in sewage and oxygen in atmosphere alternately. Layers of biomass are sheared from the surface of the media during the rotation to prevent overgrown of the fixed film. RBCs are conventionally submerged to 40% of disc diameter. Increased submergence of discs up to about 90% is also acceptable if sufficient air supply is provided at the base of the tank. This system is normally called the submerged biological contactor (SBC).

5.8.4.2 Design Requirements for RBC Plants Preceding the RBC must be a primary sedimentation tank or a secondary screening with <6 mm opening. A flow balancing tank must also be provided unless the plant is designed to peak flow. Units must be covered for aesthetics and odour control, and only approved media types are accepted.

5.8.4 Rotating Biological Contactors (RBC)


Rotating Biological Contactors use a series of rotating media for biological treatment. The rotating medium, typically made from sheets of high quality plastic, provides a surface on which organisms grow. As the media rotate, the fixed film biomass is in contact with organic pollutions in sewage and oxygen in atmosphere alternately. Layers of biomass are sheared from the surface of the media during the rotation to prevent overgrown of the fixed film.

RBCs are conventionally submerged to 40% of disc diameter. Increased submergence of discs up to about 90% is also acceptable if sufficient air supply is provided at the base of the tank. This system is normally called the submerged biological contactor (SBC).

5.8.4.2 Design Requirements for RBC Plants

Preceding the RBC must be a primary sedimentation tank or a secondary screening with < 6 mm opening. A flow balancing tank must also be provided unless the plant is designed to peak flow.

Units must be covered for aesthetics and odour control, and only approved media types are accepted.



Table 5.14 Design Parameters for RBC Plants

Description Unit Design CriteriaMinimum number of stages 3Total BOD5 specific loading g/m2/d 5 - 10

Total tank volume Based on 2 hrs at Qavg

Sludge yield kg excess sludge/ kg BOD5 consumed

0.9

Disc diameter m 2.5 - 3.5

Speed of rotation rev / min 0.5 - 1.0

Maximum peripheral velocity m/s 0.3

Depth of disc submergence % 40 - 90

Refer also to Table D.3 for duty standby requirements and relevant clause of MS 1228 for more details.

Figure 5.13 Rotating Biological Contactor (RBC) Systems



Table 5.14 Design Parameters for RBC Plants

Description Unit Design Criteria

Minimum number of stages 3

Total BOD5 specific loading g/m2/d 5 - 10

Total tank volume Based on 2 hrs at Qavg

Sludge yield kg excess sludge/ kg BOD5 consumed

0.9

Disc diameter M 2.5 - 3.5

Speed of rotation rev / min 0.5 - 1.0

Maximum peripheral velocity m/s 0.3

Depth of disc submergence % 40 - 90

Refer also to Table D.3 for duty standby requirements and relevant clause of MS 1228 for more details.

Figure 5.13 – Rotating Biological Contactor (RBC) Systems

OPTIONAL

Effluent ToRiver

Final Clarifier

FlowDistribution

Rotating Biological Contactor

Fine Screen

Balancing Tank

Screens, Grit Removal,Flow Measurement

Raw Sewage

Inlet

SewagePumpingStation

Ultimate Disposal

Sludge Storage Area MechanicalSludge Dewatering

ChemicalDosing

MechanicalSludge Thickener

Sludge Holding Tank

SludgeDrying Bed

Liquor

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5.8.5 Trickling Filter


The Trickling Filter is an established biological treatment process removing 65 to 85% BOD5 and suspended solids. The process consists of a bed of highly permeable medium. An overhead rotating distributor applies sewage to the media. The flow trickles over and flows downward to the underdrain system.

The media provides a large surface area to develop biological slime growth which is also known as zoogleal film. The film contains living organisms that break down organic material in the sewage.

Many variations of the Trickling Filters have been constructed, however the recommended designs are given in Table 5.15.

5.8.5.1 Design Requirements for Trickling Filters

Secondary screens (< 6 mm) and flow balancing tanks to equalise the flow must be provided before trickling filters.

Provisions shall be available for even distribution to achieve complete wetting of the filter media.

Figure 5.14 Trickling Filter Systems



5.8.5 Trickling Filter

5.8.5.1 General Description The trickling filter is an established biological treatment process removing 65 to 85% BOD5 and suspended solids. The process consists of a bed of highly permeable medium. An overhead rotating distributor applies sewage to the media. The flow trickles over and flows downward to the underdrain system. The media provides a large surface area to develop biological slime growth which is also known as zoogleal film. The film contains living organisms that break down organic material in the sewage. Many variations of the trickling filters have been constructed, however the recommended designs are given in Table 5.15.

5.8.5.1 Design Requirements for Trickling Filters

Secondary screens (< 6mm) and flow balancing tanks to equalise the flow must be provided before trickling filters. Provisions shall be available for even distribution to achieve complete wetting of the filter media.

Figure 5.14 – Trickling Filter Systems

RawSewage

Inlet

SewagePump Station


FineScreen

BiofilterPumpStation

Filter

FlowDistribution

Final ClarifierEffluentTo River

ChemicalDosing


Liquor


Sludge Storage Area

Sludge Holding Tank

Sludge Drying Bed

Ultimate Disposal

OPTIONAL



Table 5.15 Design Parameters for Trickling Filter

Description Unit Design CriteriaOrganic loading

(depending on filter type)Low rateIntermediate rateHigh rate

kg BOD5/day/m3

0.08 - 0.150.15 - 0.50.5 - 2.0

Recirculation of flow to head of plant

(to maintain wetting rate and improve flow)

> 1.0

Acceptable media HDPE, PVC, stone, slag, coke, etc. (random or standard arrangement)

Hydraulic loadingLow rateIntermediate rateHigh rate

m3/day/m2

1 - 44 - 1010 - 40

Sludge YieldsLow-rate filtersIntermediate filtersHigh-rate filters

kg sludge / kg BOD5 influent 0.5

0.6 - 0.81.0

Minimum depth of media m 1.5

Refer also to Table D.4 for duty standby requirements and relevant clause MS 1228 for more details.

5.8.6 Sequencing Batch Reactors (SBR) System


Sequencing Batch Reactors system is suspended activated sludge system. In this system, sewage flows into one or more reactors where biological oxidation and clarification of sewage take place within the same reactors sequentially on cyclical mode. There are five (5) basic sequences in a cycle, namely:

inflow

recycle

QQ

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1. Fill2. React (Aeration)3. Settle4. Decant5. Idle

Typically, all actions in the reactor occur at different sequence of time. In other words, the system is intermittently fill and intermittently decant. Typical SBR plant consists of a minimum of two (2) reactors in a plant. When one unit of the reactors is in fill mode, the other reactor(s) may be in the stage of react, settle, decant or idle. Recent development of SBR system leads to the emergence of variation in the operating sequences. Continuous fill and intermittently decant system is one of the variations of this system, where feeding into all rectors are continuous but the other phases (react, settle, decant, idle) are run in sequence.

In the reaction stage, oxygen supplied to the system shall be in accordance to the load to the system within the time frame of reaction cycle. This generally requires higher oxygen capacity per unit time than a continuously aerate system.

In the decant stage, there shall be sufficient time to allow for mixed liquor suspended solids (MLSS) to settle before effluent decanting begins. Decanting time is normally much shorter than fill time. Consequently, the effluent flow rate will also be much higher than influent flow rate. Hence the design of the decanting weir must be capable to handle high over-flow rate without scouring the settled sludge. Therefore, sufficient clear water depth between the minimum water level after decant and the top of the settled sludge blanket must be allowed for to minimise sludge carry over. Hence the depth of water decanted must be restricted to prevent scouring of solids.

5.8.6.2 Design Requirements for SBR Plants

All SBR plants must be designed to cater for peak flows. A minimum of a two (2) tanks system is required. Proven control system in the form of Programmable Logic Controller (PLC) with complete instruction, and operational and training manuals must be submitted together with the design. All SBR systems must be preceded with complete preliminary works. Allowance shall be provided to completely empty a tank for maintenance purposes without interrupting the operating sequence of the plant.

Table 5.16 highlights the key design requirements for an SBR plant.



Table 5.16 Design Requirements for SBR System

Parameter Unit Continuous Fill and Intermittently Decant

Intermittently Fill and Intermittently Decant

No. of Reactors unit Minimum 2 Minimum 2

Hydraulic retention time at Qavg (at average water level)

hr 18 – 24 18 – 24

F/M ratio d-1 0.05 – 0.08 0.05 – 0.30

Sludge age d 20 – 30 10 – 30

Sludge Yield kg Sludge

kg BOD5 load

0.75 – 0.85 0.75 – 1.10

MLSS (End of decant) mg/l 3000 – 4500 3000 – 4500

Cycle Time hr 4 – 8 4 – 8

DO (Reactor)

DO (Effluent)

mg/l

mg/l

0 ~ 6.5

2.0

0 ~ 6.5

2.0

Oxygen Requirement kg O2

kg Substrate

Cycle time 2.0 kg O2

Aeration Time kg substrate

Cycle time 2.0 kg O2

Aeration Time kg substrate

Decant time hrs ≥ 1.0 ≥ 1.0

Decant depth m Max 0.5 max 1.0

Decant volume % Not more than 25% of volume of Biological

Reactor at TWL

Not more than 30% of volume of Biological Reactor at TWL

Decanting device loading rate*

m3/m/hr ≤ 20 for decant draw-down from TWL

≤ 20 for decant draw-down from TWL

Minimum number of decanter

2 nos. independent decanter per tank

2 nos. independent decanter per tank

Max. pecanter length m 4.0 4.0

WAS kg sludge/d Total solids in system

Slude age

Total solids in system

Slude age

Fill volume m3 Vfill = (QP m3/hr x 1.5hr)

+ (Tfill –1.5) x QAVG (if no balancing tank)

Vfill = QAVG x Tfill (if preceded by

balancing tank)

Vfill = (QP m3/hr x 1.5hr) +

(Tfill –1.5) x QAVG (if no EQ)Vfill = QAVG x Tfill (if preceded

by balancing tank)

* For continuous fill, length to width ratio shall be based on 3 : 1* Decanting device loading rate shall be based on Vfill/decant time during

decanting.† RAS maybe necessary where length to width ratio poses dilution affect

into the inlet.

x x

WAS= WAS=

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5.8.7 Design Requirements for Hybrid Systems

A hybrid system is a recent development in biological treatment combining suspended solids and fixed film growth processes. The treatment system may be considered if the design criterion to be adopted has proven performance and result.

5.8.8 Design for Nutrient Removal for Sensitive Receiving Water

Nutrient removal is required for effluent discharge to lakes and stagnant water bodies to prevent eutrophication or other potential impacts that may impede the sensitivity of the receiving water. Nutrient removal can be achieved via:a) Biological treatment.b) Physical treatment.c) Chemical treatment.

It has been emphasised in the beginning of this chapter, all biological treatment system shall be designed to achieve ammonia reduction and where necessary anoxic zone/stage to be added to encourage denitrification for total nitrogen removal.

The biological phosphorus removal mechanism is based on the fact that bacteria are capable of storing excess phosphorus as polyphosphate and removing simple fermentation substrates produced in the anaerobic zone and assimilating them into storage products within their cells. Hence, the design for of the biological treatment shall follow the following for plants where nutrient removal (nitrogen and phosphorus) is required, design parameters:

Table 5.17 Design Requirement for Biological Nutrient Removal System

Item Design Parameters HRT (hrs)

MLSS

(mg/l)Internal Recycle

1 1st stage anaerobic 1 - 2 2 000 – 6 000 RAS from clarifier2 1st stage anoxic 2 - 4 2 000 – 6 000 2 to 1 (MLSS

recirculation ratio)3 1st stage aerobic (oxic) 8 - 12 2 000 – 6 000 3 to 2 (MLSS

recirculation ratio)4 2nd stage anoxic 2 - 4 2 000 – 6 000 Mixing5 2nd stage anaerobic 1 - 2 2 000 – 6 000 Mixing6 2nd stage aerobic (oxic) 4 2 000 – 6 000 -



It has been emphasised in the beginning of this chapter, all biological treatment system shall be designed to achieve ammonia reduction and where necessary anoxic zone/ stage to be added to encourage denitrification for total nitrogen removal.

Figure 5.15 Typical Process Flow Diagram for Biological Nutrient Removal System

Alternatively, both physical and chemical treatment may be used to remove phosphorus in wastewater.

The designer shall take all necessary consideration in the design in relation to the specific requirements of the receiving water in determining the actual nutrient removal requirement on the case by case basis.



It has been emphasised in the beginning of this chapter, all biological treatment system shall be designed to achieve ammonia reduction and where necessary anoxic zone/stage to be added to encourage denitrification for total nitrogen removal.

Figure 5.15 - Typical Process Flow Diagram

for Biological Nutrient Removal System

Alternatively, both physical and chemical treatment may be used to remove Phosphorus in wastewater. The designer shall take all necessary consideration in the design in relation to the specific requirements of the receiving water in determining the actual nutrient removal requirement on the case by case basis.

1st. Anaerobic

1st.Anoxic

1st.Aerobic

2ndAnoxic

2nd.Anaerobic

2nd.Aerobic

Clarifier Effluent

To getphosphate

Back

To getnitrate bac k

RAS

Q

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5.9 Design of Secondary Clarifiers

5.9.1 Purpose

Effluent from biological processes contains large populations of micro-organisms (MLSS). Secondary clarifiers provided after the biological system allow the mixed liquor organisms/ solid to settle. Clear supernatant is discharged as the effluent, while some of the settled microorganisms are returned to the biological treatment system to maintain the MLSS concentration and excess microorganisms are removed as biosolid to the sludge treatment facility.


The design requirements shall include:

I) General

a) Minimum retention time for settlement.b) Maximum settling velocity for settlement.c) Sludge hopper to collect settled sludge.d) All clarifiers must be equipped with sludge scrapers to skim

sludge from the bottom unless they are designed with a 60o hopper bottom.

e) All clarifiers must be equipped with scum skimmer to remove scum from the surface. The scum collected must be drained (where necessary) and disposed off. Returning the scum to the preliminary system or the biological system is not permitted.

f) Multiple hopper are not permitted.g) Stilling basin to prevent hydraulic shock circuiting.h) Bottom slope at clarifier floor. i) Facilities to dispose scum and sludge.j) Appropriate feed and outlet pipe with hydraulic consideration.k) Effluent collection channel to be of glazed finish/tiles.l) Proper maintenance access to all components.m) Properly designed air lift pumps are only permitted for PE less

than 1000.

II) Weirs

a) If insufficient length is available, then considerations shall be given for the use of double weir.



b) Cascading V-notch is preferred over rectangular weirs.c) Slots in the weir shall be provided to allow for level adjustment

during the installation stage.d) Broad crested weirs are not encouraged.e) All parts of the weirs must be visible and accessible for regular

cleaning.f) Type of weir and the hydraulic calculation for the weir proposed

must be submitted.

III) Circular Clarifiers

a) The maximum diameter permissible is 50 m and a reasonable allowance between tanks shall be provided for vehicle access.

b) The minimum side water depth shall be 3.0 m. Greater side water depths may be used if it can be shown that the mixed liquor is well denitrified in the aeration tank.

c) Flow distribution channel/chamber shall be provided for flow isolation or equalise flow distribution.

d) The scraper tip travelling speed shall not exceed 0.03 rpm. A multiple stage reduction unit must be incorporated to achieve such speed.

IV) Rectangular clarifiersa) Shall not be wider than 6 m per tank to allow for scraper removal,

unless other approved scraper units are available.b) Multiport wall and baffled inlet shall be provided.c) Slide gates shall be used to isolate each tank.d) Allowance also shall be provided for vehicle movement between

unit processes for maintenance purposes.e) Scraper travelling speed shall be between 0.3 – 0.6 m/min.

Refer also to relevant Clause of MS 1228 for more details.

5.9.3 Multiple Hoppers

Multiple hoppers are not accepted. This is due to the settling characteristics of the particles in the flow. Larger and heavier particles settle faster than smaller and lighter particles, creating difference in the distribution of sedimentation in different hoppers. This will present operational difficulties because sludge removal from the hoppers is unequal. To avoid the non-uniform withdrawal of sludge, each hopper in the multiple hopper configuration needs a separate pipe and pump or valve on each outlet.

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Table 5.18 Design Parameters for Secondary Clarifiers


PE ≤ 5,000 PE > 5,000

Minimum number of tanks 2 * 2

Tank configuration Square Circular Rectangular

Circular

Rectangular #

Minimum side water depth m 3** 3

Minimum hydraulic retention time (HRT) at Qpeak

hrs 2 2

Surface overflow rate at Qpeak m3/d/m2 ≤30 ≤30

Solids loading rate at Qpeak kg/d/m2 <150 <150

Solids loading rate at Qavg kg/d/m2 <50 <50

Weir loading rate at Qpeak m3/day/m <180 <180

Return activated sludge (RAS) pumping rate

Continuous Continuous

Waste activated sludge (WAS) pumping rate

Continuous or batch

Continuous or batch

Sizing of rectangular tanks

Length : Width 3:1 or greater.

Maximum side water depth m 3.0

Width : Depth 1 : 1 to 2.5 : 1

Sizing of circular tanks

Side water depth, minimum m 3.0 **

Floor slope wall 1:12

Notes:* For PE less than or equal to 1000 a single clarifier is acceptable.# Rectangular tanks are acceptable if equipped with automatic scraping and

desludging devices.

** For square clarifier with 600 slope minimum 1 m side water depth shall be provided.



5.10 Disinfection

Disinfection refers to the selective destruction of disease causing organisms in sewage effluent.

Methods of disinfection can be physical, chemical or radiation.

Continuous disinfection is required for those areas where the discharge from the sewage works will cause detrimental effect onto the receiving water course, such as bathing beaches, lakes, etc.

The Commission reserves the right to determine the need for the provision of a continuous disinfection facility.

The common forms of disinfection that are available for wastewater applications are:a) Chlorination b) Ultra-violet (UV)c) Others

Chlorination is by far the most common type of disinfection used world-wide. This is due to its effectiveness in providing a good pathogen kill with relative simplicity in operation and maintenance. However, chlorination using chlorine gas, requires a higher degree of operational skills and poses potential health and safety hazards in the shipping and handling aspects. Therefore, to reduce these hazards, only liquid or solid hypochlorite (sodium or calcium) shall be used.

Ultra-violet (UV) disinfection differs from chemical disinfection in that it uses irradiation to induce photobiochemical changes within the micro-organisms. To ensure effective photochemical reaction taking place, one of the conditions is that such radiation must be absorbed by the target molecule (organism). The other condition is that sufficient radiation energy to alter chemical bonds is made available. Given the conditions above, it is critical that the effluent prior to disinfection must be relatively clear of suspended solids. As such, for UV disinfection to be highly effective in wastewater applications, filtration of upstream of the UV unit must be made available.

Other forms of wastewater disinfection that are available are maturation ponds and ozonation. Maturation ponds have been used widely and successfully in Malaysia. However, the drawback is that a relatively large area of land is required to provide sufficient retention time in the pond for the decay of pathogens. Ozone disinfection involves the direct ozone oxidation or by reaction with the radical by-products of ozone decomposition. However, due to ozonation’s relatively new status in wastewater applications and higher costs at small scale facilities, its usage for disinfection is still limited.

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All new STPs must have provision for disinfection infrastructure such as contact tank and other necessary structures. The provision of the disinfection facilities and equipment shall be in accordance to Table 5.19 below. The disinfection shall be carried out in continuous or intermittent mode.

Table 5.19: Requirements for Disinfection Facility

Description Continuous IntermittentClass of STP* Class 4 Class 1

Class 2

Class 3Type of Disinfection Chlorination

Ultra-violet (UV)Ozone

Chlorination

Facility (1duty/1standby) for equipment

Basic facility structure.

* The Commission may impose separate requirements on case by case basis.

Figure 5.16 Schematic illustration of ultraviolet disinfection system with stilling plate for flow conditioning and

elongated weir for level control



5.10.1 Design Requirements All new STPs must have provision for disinfection infrastructure such as contact tank and other necessary structures. The provision of the disinfection facilities and equipment shall be in accordance to Table 5.19 below. The disinfection shall be carried out in continuous or intermittent mode.

Table 5.19: Requirements for Disinfection Facility

* The Commission may impose separate requirements on case by case basis.

Figure 5.16 – Schematic illustration of ultraviolet disinfection system with

stilling plate for flow conditioning and elongated weir for level control

FLOW PDC

COVER PLATES OR GRATING STAINLESS STEEL WEIR

TOP VIEW(Cables removed for Clarity)

"A""A"

SECTION 'A' - 'A'

LEVEL PROBE

FRONT ACCESS

ULTRAVIOLET LAMP RACKS

COVER PLATES OR GRATING

STILING PLATES

FLOW

CONTROL PANEL ANDPOWER DISTRIBUTION CENTRE

Description Continuous Intermittent

Class of STP* Class 4 Class 1

Class 2

Class 3

Type of Disinfection Chlorination

Ultra-Violet (UV)

Ozone

Chlorination

Facility (1Duty/1Standby) for equipment

Basic facility structure.



Figure 5.17 Profile schematic of lamp modules relative to inlet and outlet structure



Figure 5.17 – Profile schematic of lamp modules relative to inlet and outlet structure

Flapper Gate Level Control

EffluentChannel

Disinfection ModulePower & DataInterconnect Cables

UV Protective

Inffluent Channel

Flow

Flow

ServiceArea

Electrically OperatedJib Host

Station Cleaning drain

Station CleaningLiner with covet304 Stainless Steel

Signal Cablefrom Plant Flow meter

Power Cable

Power DistributionData center (PDDC)

A A

PLAN VIEW

SECTION "A - A"

InfluentChannel

ChannelInfluent

Figure 5.18 Chemical-feed system schematic

CALIBRATION COLUMNRELIEF VALVE

CHEMICAL FEED PUMP

BACK PRESSURECONTROL

STORAGE TANK



Figure 5.17 – Profile schematic of lamp modules relative to inlet and outlet structure

Flapper Gate Level Control

EffluentChannel

Disinfection ModulePower & DataInterconnect Cables

UV Protective

Inffluent Channel

Flow

Flow

ServiceArea

Electrically OperatedJib Host

Station Cleaning drain

Station CleaningLiner with covet304 Stainless Steel

Signal Cablefrom Plant Flow meter

Power Cable

Power DistributionData center (PDDC)

A A

PLAN VIEW

SECTION "A - A"

InfluentChannel

ChannelInfluent


CALIBRATION COLUMNRELIEF VALVE

CHEMICAL FEED PUMP

BACK PRESSURECONTROL

STORAGE TANK


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5.10.1.1 Continuous Disinfection

I) Disinfection with Ultra-Violet (UV)

a) Filtration ahead of the ultra-violet disinfection is a must in order to ensure consistent and reliable disinfecting performance, as well as, to reduce maintenance, such as, fouling of the UV lamps.

b) The performance of the UV unit shall meet a UV transmittance level of secondary effluent of at least 60% on a filtered basis. If a lower transmittance level is encountered, it shall be compensated with the reduction in the spacing of lamps and/or usage of an advanced higher intensity system to compensate the lower tranmissibility of the sewage effluent.

c) The channel for the UV shall be open, long and narrow to encourage plug flow and avoid short circuiting.

d) As a guide, the average sizing is roughly 10 conventional 1.5 meter lamps per 1,000 m3/day at peak flow. However, the actual sizing shall be site specific and subjected to effluent quality desired as well as the level of upstream treatment provided.

e) In the design to house the UV modules, it is important to include proper inlet and outlet structures and consider the approach and exit flow conditions.

f) A stilling well is required to distribute the flows and equalise the velocities across the cross-section of the channel. The stilling plate shall be placed at least 5 meters in front of the first lamp bank. Otherwise, the channel should have an undisturbed straight line of two (2) or three (3) lamps length.

g) Sufficient distance shall be allowed between lamp banks (0.5 m to 1.0 m) and two (2) to three (3) lamp lengths between the last bank and the downstream level control device.

h) In large system applications, a multichannel configuration is required. This is to allow the inlet structure to satisfy the dual requirements of inducing flow and to allow even distribution of flow among operational channels. Channel inlet structures shall allow for hydraulic isolation of individual channels during low flow and routine maintenance. In operation, the multichannel design shall be controlled to maintain a minimum velocity through any one channel.

i) Wastewater within the channel must be maintained at a constant level with little fluctuations. This shall be accomplished by using a mechanical counter balance gate downstream of the lamp batteries.

j) It is crucial to avoid a dryness state in the channel during low or no flow conditions to prevent the fouling of the quartz jackets



surrounding the lamps and/or causing damage to the UV modules. To alleviate this, for a small STP, a fixed or adjustable weir should be used. However, sufficient weir length shall be provided to avoid water level fluctuations. In larger STPs using the multichannel design, these flow fluctuations can be attenuated by the opening and closing of channels as needed.

k) Control systems should be simple. Its objective is to ensure that the system loading can be maintained and disinfection accomplished, while conserving the operating life of the lamps. In small STPs, the control system shall consists, of a full duty unit in operation at all times with a similar redundant unit on standby. Manual control and flexibility should be made available to enable the operator to bring portions of the systems in and out of operation, as needed, to adjust for the changes in flow or water quality. In larger STPs, a complete automation is warranted for plants using the multi channel design.

l) Safety aspects of an UV disinfection facility involve mainly the electrical hazards and protection from the exposure to UV radiation. The exposure risks could be minimised as long as the operating lamps are submerged and the lamp batteries are shielded. The UV lamps shall not be operated in air and unshielded. All systems must be equipped with safety interlocks that shut down the modules if they are moved out of their operating positions or the wastewater level falls, leaving any or all lamps exposed to air. Electrical hazards can be minimised by the inclusion of ground-fault-interruption circuitry with each module. This feature is a requirement for all UV systems.

m) The design of the UV system shall allow for easy access to the lamp modules for cleaning and other maintenance tasks. The installation shall have adequate working area for maintenance and servicing of the modules when taken out of the channels. Cleaning of the lamps shall be accomplished using mechanical wipers which may be fitted with chemical injectors and with chemical baths when taken out of the channels.

n) A drainage system back to the head of the treatment works shall be provided to drain back water from the reactors, channels and other related tankage. In addition, a permanent clean-water system is to be made available to allow for rinsing and cleaning needs. A bypass around the UV disinfection facility is to be made available in the event the system is shut down completely for maintenance.

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Table 5.20 Design Guides for Disinfection with Ultra-Violet(UV)

Description Design CriteriaUV system

Minimum UV Dose (at 254 nm) at end of lamp life

Maximum Total Suspended Solids in effluent to UV system

Maximum Mean Particle Size in effluent

UV Transmittance at 254 nm

Lamp life

Minimum UV output at end of lamp life

Operating Temperature

Relative Humidity

UV detection System

Lamp Sleeve Cleaning system

Standby lamps

Disinfection Standards

Mounted in open channel type*Must be preceeded with filtration.

30 mJ/cm2 (30,000 µWs/cm2)at Qpeak

< 10 mg/l

20 microns

65%

≥ 12 000 hours

80%

18 – 40 oC

> 95% at 40 oC

UV sensor, transmittance, dose pacing

a. Mechanical wipers and out of channel chemical cleaning.

b. Additional 25% more lamps shall be provided for mechanical wipers.

25% to be provided with min 2 lamp banks

In accordance with receiving water requirement or effluent usage

Note:*Enclosed system shall be permitted under special circumstances

II) Disinfection with Hypochlorite

a) Calcium and sodium hypochlorite are hazardous chemicals to handle and use. Calcium hypochlorite is classified as a corrosive



and rapid oxidant, while sodium hypochlorite is a corrosive agent. Eye protection, access to an emergency eyewash system and showers must be made available to the operators. Also, direct contact with the undiluted hypochlorite is likely to cause burns to the skin and clothing. Therefore, it is imperative that protective clothing which includes rubber gloves, must be worn by operators when working with these chemicals. When calcium hypochlorite is being transported in the powder form and mixed in water to form solutions, the operator should always wear eye protection and dust masks. All areas exposed to hypochlorite should be washed thoroughly.

b) Chlorine dosage ranges from 6 to 10 mg/l for effluent. The dosage rate is affected by the suspended solids and ammonia present in the effluent, mixing employed, contact time and the control strategies used for dosing.

c) Proper mixing is important for effective disinfection. d) If a hydraulic jump is employed as a mixing device, the submergence

of the diffuser shall not be less than 230 mm (9 in.) below the water surface and placed before the hydraulic jump at the minimum flow. The hydraulic jump is effective in mixing when the head loss exceeds 0.6 m (2 ft). To ensure adequate mixing is achieved, the evaluation of the flow characteristics should be carried out. As a minimum, the Reynolds number shall be 2.1 x 104 for pipe flow and Froude numbers between 4.5 and 9 for open channels is recommended.

e) Hypochlorinators are chemical-feed pumps used for feeding sodium or calcium hypochlorite. The basic components are a storage reservoir or mixing tank for the hypochlorite solution; a metering pump that consists of a positive displacement pumping mechanism, motor or solenoid and a feed rate adjustment device; and an injection device. Depending on the size of the system, a plastic or fiber-glass vessel may be used to hold a low-strength hypochlorite solution. It is not acceptable to use metals commonly used in the construction of storage tanks to hold the hypochlorite solutions because of the corrosive nature of the chemical which will also expedite the decomposition of the liquid hypochlorite.

f) Feeding of calcium hypochlorite will require a mixing device, usually a motorised propeller or agitator located in the tank. Also, in the tank is a foot-valve and suction strainer connected to the suction inlet of the hypochlorinator.

g) The hypochlorinator shall be feed rate adjustable. h) The injection fitting shall be similar to that used in the gas

chlorinator.

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i) A chlorine contact tank shall take the form of rectangular serpentine chamber. Circular chambers for disinfection are not acceptable.

j) Local supply of water shall be made available for the dilution of powder calcium or sodium hypochlorite. A breaker tank for supply of water is required for the proper running of the hypochlorinator. If deemed necessary, the water pressure maybe increased with the provision of water booster pump.

k) Pipe works should be suitable for chlorination applications and well supported.

l) Provision for draining the chlorine contact chamber is required for cleaning and maintenance purposes. This shall include a drain valve located at the bottom of the downstream end of the chamber. The point of discharge shall ensure that adequate treatment is given and this could be done through pumping the content from the chamber and return to the head of the treatment plant.

m) A bypass around the chlorine contact chamber shall also be provided to enable flows to be bypassed during maintenance or servicing. There shall be penstocks upstream and downstream of the chlorine contact chamber for isolation purposes.

n) Adequate access with sufficient turning radius for the vehicle to carry in the chemicals to the disinfection system shall be provided.

o) A small housing structure shall be provided to house hypochlorinator, associated chemicals and ancillaries. Some important consideration have to be given in the design of adequate space for the operators to replace and fill the chemicals, washing facility, eyewash, record keeping of chemical dosing, effluent flowmeter data among others. Due to the hazardous nature of the disinfection system housed, a locking system shall be made available to deter vandalism and promote safety of the plant.

The structure housing the hypochlorinator and the chemicals shall be bunded to prevent the possibility of spillage. The sizing of bunds shall correspond to the total volume of the storage/solution tanks.



Table 5.21 - Design Guide for Disinfection with Hypochlorite

Type Calcium or SodiumDosage 6 – 10 mg/lMixing Mechanical, baffles or hydraulic jump.Hypochlorinator system

Feed rate adjustable

Equipment 1 duty/ 1 standbyContact TankContact Period 15 minutes at Qpeak

Maximum depth 3 mDepth : Width 2 : 1Min no. of passes 4Length : Width at each pass

6 : 1

Wetted Depth : Width

< 2:1

5.10.1.2 Intermittent Disinfection

The design requirements for intermittent disinfection facility shall comply to the following:

a) Due to the infrequent usage and other health and safety considerations in an intermittent disinfection system, ONLY liquid hypochlorite, either calcium or sodium, shall be used.

b) A chlorine contact chamber shall be provided with a minimum of 15 minutes hydraulic retention time at peakflow. This chamber shall be of a rectangular configuration with aspect ratios optimised to promote plug flow conditions. The recommended aspect ratios are as follows:

i) Length to width (each “Pass”): 6:1ii) Minimum number of passes: 4iii) Height to width of the cross-section of the wetted section:

< 2:1iv) Depth of chlorine contact chamber is typically 2 – 3 m.

The corners shall be rounded to reduce the dead flow areas and the velocity through the contact chamber shall be sufficient to minimise solids deposition.

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v) horizontal baffles shall be used to ensure the plug flow conditions are maintained and to minimise the possibility of short circuiting.

vi) Upstream of the contact chamber, a dosing coupling for easy hook-up of the mobile hypochlorite disinfection system shall be an inherent part of the chamber design.

c) A breaker tank for supply of water adjacent to the contact tank is required to provide water for the mixing of powder hypochlorite and for cleaning or cleansing of the contact chamber. If deemed necessary, a water booster system shall be provided to increase the water pressure for the intended application.

d) Draining provision must be made available to allow for complete drainage of the chlorine contact tank. For this purpose, a drain valve shall be provided at the bottom of the downstream end of the chamber.

e) Penstock/slide gate shall be provided at the upstream and downstream end of the contact chamber. This allows for the effluent flow from the treatment plant to bypass this chamber when its service is not required.

f) Adequate access shall be provided for a portable hypochlorinator unit mounted on a skid to be brought by a truck to the contact chamber area when disinfection is required. A concrete pad adjacent to the contact chamber shall be provided for the skid mounted hypochlorinator to be situated when in use.

g) Power supply shall be adequately provided and located close to the contact chamber to run the intermittent disinfection system.

Table 5.22 Design Guide for Intermittent Disinfection

Type Calcium or Sodium

Dosage 6 – 10 mg/l

Mixing Mechanical, baffles or hydraulic jump.

Hypochlorinator system

Feed rate adjustable

Equipment 1 duty/ 1 standby



Table 5.22 Design Guide for Intermittent Disinfection (cont.)

Type Calcium or SodiumContact TankContact Period 15 minutes at Qpeak

Maximum depth 3 mDepth : Width 2 : 1Min no. of passes 4Length : Width at each pass

6 : 1

Wetted Depth : Width < 2:1

5.11 Design of Flow Measurement Devices

5.11.1 Purpose of Flow Measuring Devices

Flow measuring devices are necessary for monitoring of plant operation and process control continuously. The purposes of flow devices are:

a) to maintain flow records periodically for future reference, especially when plant expansion is needed.

b) to identify the flow pattern which may be due to population growth or infiltration.

c) Statutory requirement by the DOE to maintain flow records at all sewage works.

d) To establish operational cost for treatment of sewage.

5.11.2 Design Requirements for Flow Devices

Flow devices are mandatory for all STP, regardless of size.

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Table 5.23 Design Parameters for Flow Devices

DescriptionDesign Criteria

PE ≤ 5,000 PE > 5,000Location of flow meter

Inlet or Outlet Inlet and Outlet

Type of Flow Measurement

Closed Conduit or Open Channel

Closed Conduit or Open Channel

Type of flow meter V- notch (Outlet Only) Rectangular Weir (Outlet Only) Flumes

Electromagnetic

Ultrasonic

V-notch (Outlet Only) Rectangular (Outlet Only) Flumes

Electromagnetic

UltrasonicMethod of measurement

Automated or manual •measurement of Staff gauge to measure height of crest with calibration curves / tables

Automated devices linked to data logging with integrator and transmitted to chart recorder (minimum 7 days chart time)

Measurement times

Continuous or Intermittent Continuous

5.12 Sludge Holding, Treatment and Disposal

5.12.1 Introduction

All treatment processes are capable of producing significant quantities of sludge which requires to be further treated. The sludge comprises essentially inert and organic matters that are biodegradable and non-biodegradable present in sewage, and bacterial cells generated by the biological treatment processes. The treated sludge, often referred as biosolids is ready for safe disposal or reuse.

The importance of sludge management increases with the increase in the amount of sewage treated. Space has to be allowed within the premises of an STP to accommodate sludge treatment, handling and storage facilities.

All sludge need to be treated for safe disposal back to the environment. The minimum requirement for sludge treatment is to achieve stabilize sludge with a 20% dry solid content.



For large scale development whereby the full sludge generation will only be achieved over a certain time period, proper sizing/modulation of sludge treatment facilities need to be provided in order to achieve the immediate needs for sludge treatment.

5.12.2 Sludge Strategy in General

Figure 5.20 shows the typical sludge treatment and disposal strategy which consists of three main stages.

a) Stage 1 - Preliminary treatment and digestion

b) Stage 2 - Conditioning and dewatering

c) Stage 3 - Utilisation and disposal

I) Stage 1 - Preliminary Treatmentand Digestion

Preliminary treatment may include reception or holding facility for screened sludge, primary thickening and digestion facilities.

For imported sludge the reception facility may comprise of an unloading area, screen chamber, reception tank and transfer pump(s).

Thickening equipment, such as, centrifuge, drum thickener or gravity belt thickener is provided to thicken the raw screened sludge from about 1% dry solids content to about 6% dry solids content. To assist the thickening process, an ‘in-line’ polymer dosing system or chemical conditioning shall be provided.

Two types of digestion facilities are available for digestion after the thickening: aerobic and anaerobic digestion.

Secondary thickening is recommended to reduce the volume of digested sludge, which will then reduce the size and the number of the next treatment process unit, i.e., dewatering equipment.

II) Stage 2 - Conditioning and Dewatering

Dewatering can be achieved by two (2) methods : mechanical dewatering and non-mechanical dewatering.

a) Mechanical dewatering such as belt filter press, centrifuge or filter press is provided for sludge dewatering purposes. To assist the mechanical dewatering equipment in achieving optimum level of cake dryness, an ‘in-line’ polymer dosing system or chemical conditioning shall be provided.

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b) Non-mechanical dewatering, e.g. drying beds or sludge lagoons is often used

For a facility serving ≥ 10,000 PE, the drying beds must be designed to support mechanical/machine lift for the purpose of clearing the dried sludge.

Sludge lagoons of about 2 m depth are also used for sludge stabilisation and drying. The sludge lagoons shall be sized to receive sludge for a period of at least 6 months and are allowed to undergo stabilisation through evaporation and drying for another 6 months period. The lagoons shall be lined with either PVC lining, concrete or 600 mm thick clay lining. An access ramp shall be provided to allow mechanical equipment access to clean dried sludge.

III) Stage 3 - Utilisation and Disposal

After the dewatering process, an on-site storage for 30 days of the treated bio-solid shall be provided. The storage structure shall be covered with roof and provided with partly opened walls to allow for proper ventilation.

Finally, the bio-solid is either composted and/or applied directly for land reclamation (i.e., for ex-mining land), land application (i.e., for certain types of agriculture land and forest land/reforestation) or used as top soil cover at land fill site. The ultimate disposal of bio-solid is the responsibility of the plant operator.

5.12.3 Provision of Sludge Holding, Treatment and Disposal

The Service Licensee will advise on current capacity in its existing sludge treatment facilities, suitable sludge stabilisation, dewatering and final disposal of the sludge shall be provided.

If the Service Licensee has the capacity to receive sludge generated from the development, then the project proponent has the option to negotiate with the Service Licensee to dispose off the sludge at the existing facility. In this case, a sludge storage tank with a minimum capacity to hold for 30 days with the sludge thickened to 1% solids is acceptable. Otherwise, the sludge shall be stabilised, dewatered and prepared in a suitable form for disposal.

Different types of STPs produce different quantities of bio-solid. The principal assumptions adopted on waste generation rates are summarised in Table 5.24.



Table 5.24 - Sludge Generation Rates

Treatment System Unit Generation Rates Comments

Primary Sludge

Primary Clarifier 0.5 kg sludge/kg solids input Based on continuous sludge withdrawal

Imhoff Tank 0.15 kg sludge/kg SS input Based on average 6 month desludging period

Secondary Sludge

Conventional Activated Sludge System

0.8 to 1.0 kg sludge/kg BOD5 removed

Standard A/B

Extended Aeration or Oxidation Ditch

0.4 to 0.6 kg sludge/kg BOD5 removed

Standard A/B

RBC/SBC/High Rate Trickling Filter System

0.8 kg sludge/kg BOD5 removed Standard A/B

Hybrid System 0.4 kg sludge/kg BOD5 removed Standard A/B

Note:Based on the above assumptions, the quantity of waste sludge requiring treatment and disposal can be estimated. Refer also to design guides related to each of the above individual processes.

5.12.4 Design Criteria

The ultimate aim of sludge treatment is to achieve at a minimum stabilised sludge with dry solids content of 20% for final disposal. A combination of various unit processes may be used to achieve this minimum requirement.

I) Sludge Reception/Sludge Holding

a) An unloading area is normally provided to receive sludge tankers delivering imported sludge to the facility, if necessary. It should also includes a parking area for sludge tankers.

b) A mechanically raked screen with 12 mm opening together with a manually raked by-pass screen shall be provided where necessary.

c) Connection fitted female coupling with ball valve shall be provided at the reception facility for the connection of desludging tanker’s hose.

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d) Minimum three (3) days sludge holding capacity of between 1 to 4% dry solids content sludge (depending on the types of sludge) shall be provided after the screening process.

e) Overflow pipe shall be provided at sludge holding tank to aeration tank to avoid overflowing.

f) Adequate ventilation/air extraction fan shall be provided at the thickening/dewatering house.

II) Solid Thickening

Thickening is a process used to increase the solids content of sludge by removing a portion of the liquid fraction. It is generally accomplished by physical means, including co-settling, gravity settling, flotation, centrifugation, gravity belt and rotary drum. The design parameters for sludge thickening equipment shall follow Table 5.25 below:

Table 5.25 - Design Parameters for Sludge Thickening

Type of Thickening % Dry Solids

Polymer System

Speed of Sludge

feed pump

Backwash water

system

Picket Fence Gravity Thickener 1.5

n/a n/a n/aDissolved Air Flotation 2

Belt Thickener 4 Yes with appropriate

polymer turndown

ratio

< 300 rpm YesDrum Thickener 4

Centrifuge4

Note:a) Mechanical thickener shall be designed for 8 hrs/day and 5 days/week

operation.b) For belt, drum and centrifuge thickener, three polymer injection

points shall be providedc) Potable water to be provided for polymer mixing system.



III) Solid Digestion

Sewage biosolids in its natural state (raw) is rich in pathogenic organisms, easily putrescible and rapidly developing unpleasant smells. Stabilization processes were developed with the purpose of stabilizing the biodegradable fraction of organic matter present in the bio-solids, thus reducing the risk of putrefaction as well as diminishing the concentration of pathogens. The stabilization processes can be divided into:a) Biological stabilization – specific bacteria promote the stabilization

of the biodegradable fraction of the organic matter.b) Chemical stabilization – chemical oxidation of the organic matter

accomplishes sludge stabilization.c) Thermal stabilization – heat stabilizes the volatile fraction of

sludge in hermetically sealed containers.

The most widely used stabilization process is biological stabilization via anaerobic and aerobic digestion.

Table 5.26 - Design Parameters for Aerobic and Anaerobic Digestion


Aerobic Digestion

Anaerobic Digestion

Number of Tank, Minimum No. 2 2Min. Solids Retention Time Days 10 18 Organic Loading Rate KgVS/m3.d 1.6 – 4.8 0.8 – 1.6Typical Feed Solids Concentration

% 2 2 - 6

Type of Mixing AeratorsDiffusers

Gas InjectionMechanical StirringMechanical Pumping

Min. Water Depth, minimum m 3 7.5Tank Shape Cylindrical

RectangularCylindricalEgg-Shaped

Tank Dimension, maximum m 25 diameter25 length

25 diameter

Dissolved Oxygen mg/L 1 - 2 -

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IV) Sludge Dewatering

Table 5.27 Recommended Design Parameters for Sludge Stabilisation and Dewatering

Descriptions UnitDesign Considerations

PE ≤ 2,000 PE > 2,000Sludge StabilisationType of stabilisation process

Simple anaerobic or aerobic digestion

Ambient anaerobic digestion with good mixing facility

Hydraulic retention time (HRT) minimum

Days 30 30

DewateringType of device

Belt press Centrifuge Filter press Drying bed

Belt press Centrifuge Filter press Drying bed *

Minimum dry solids (content after dewatering)

% 20 20

Operating period of mechanical thickening and dewatering facility

5 days/week # 8 hours/day 250 days/year

5 days/week # 8 hours/day 250 days/year

Handling capacity of drying bed

4 weeks cycle on 450 mm thick feed †

4 weeks cycle on 450 mm thick feed †

Covered storage area 1 month holding 1 month holding

Notes:a) Access ramp of at least 1.5 m wide shall be provided at all sludge drying

beds

* Drying beds must be designed to support mechanical/machine lift for more than 10 000 PE.

# Design to be based on one full-time working shift only.† In computing the area requirements of a sludge drying bed, the designer may

assume a maximum 450 mm depth of sludge feed to the bed. The actual quantity of sludge from the upstream unit processes needs to be computed before sizing the bed. Each bed may be designed to handle a maximum of 7 days continuous feed. The next feed to the same bed shall only be after a minimum of 21 days from the last feed. A one-third (1/3) reduction in actual land area requirement will be acceptable if fully covered drying beds are provided. Reduction shall only apply to the total surface area of drying



bed. No reduction is allowed for the drying bed thickness. Structures and materials used for the drying bed covers shall be designed to an acceptable structural strength and of acceptable quality to withstand local weather conditions.

Figure 5.20 Sludge Treatment and Disposal Strategy



Structures and materials used for the drying bed covers shall be designed to an acceptable structural strength and of acceptable quality to withstand local weather conditions.

Figure 5.20 – Sludge Treatment and Disposal Strategy

Untreated Sludge

Screening

Primary Thickening

Anaerobic Digestion Aerobic Digestion (Optional)

Secondary Thickening (Optional)

Possible disposal of Liquid Sludge

Chemical Conditioning

Drying BedsMechanical Dewatering Drying Lagoons

Storage at works

Transportation from works

Composting

Land Application Forestry/AgricultureLand Reclamation Landfill Site

To inlet of STW or

on-site Liquor Treatment Plant

Utilisation and Disposal

Conditioning and Dewatering

Preliminary Treatment and Digestion

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V) Ultimate Disposal The treatment plant project proponent has to indicate in the proposal the ultimate disposal options and actual volume for disposal throughout the life time of the plant.

5.13 Tertiary Treatment

5.13.1 Introduction

Tertiary treatment is associated with the requirements to further reduce or remove pollutants beyond the levels achieved by common secondary treatment processes. Such requirements can be in the forms of the removal of nutrients, such as, nitrogen and phosphorus; lower BOD5 or SS levels; or trace elements of toxic constituents, such as, heavy metals or refractory organics.

The various methods of tertiary treatment include simple maturation ponds, adsorption, chemical treatment and filtration; air stripping, mambrane or reoxygenation.

Tertiary treatment is required before discharging to very sensitive receiving waters. The Commission will specify the need for such treatment on a case-by-case basis, depending upon the sensitivity of the project.

5.13.2 Design Requirement

I) Filtration systema) Filtration is the most common tertiary treatment system used to

remove suspended or colloidal matter in the effluent.

b) Backwashing shall be limited to once per day. The volume of backwash water shall not exceed 10% of plant throughout. Backwash water shall be stored in a buffer tank before being return to the inlet of the plant.

c) Where used, the facility for dosing conditioners shall be provided at the inlet of the filter system.

d) On-line turbidity meter, level detector and flow measurement shall be utilized to measure filter performance.

e) If the filters are housed in a building, adequate and safe access shall be provided for maintenance purposes.

f) The filters shall have automated backwash features and sized adequately to allow continuous filtration.



g) For package plants, it is preferred to use FRP as the filter vessel. However, fabricated steel is also acceptable provided that protective coatings are included. For larger plants, the use of reinforced concrete is encouraged.

II) Adsorption (Activated Carbon)a) Activated carbon is used to remove small quantities of refractory

organics, as well as inorganic compounds, such as nitrogen, sulficles and heavy metals.

b) Adsorption shall be preceded by filtration using granular media to ensure a consistant feed quality, which is affected by pH, temperature and flow rate.

c) Uniform feedwater to avoid any surges that might adversely affect the carbon adsorption.

d) Clarity of feedwater is important to avoid restriction of pores or build up of materials within the pore structure.

e) Backwashing rate and the frequency required depend on the hydraulic loading and operational method. Typical duration of backwashing is 10-15 minutes.

III) Chemical Treatmenta) Chemicals can be used as tertiary treatment for acid-base

neutralisation and precipitation of phosphorous.b) Phosphorous precipitation requires the addition of coagulants,

which usually are lime, alum, sodium aluminate, ferric chloride and ferrous sulfate.

c) Dosing systems and safety features to be provided to assure the operation and maintenance of the systems can be carried out in a safe and healthy environment.

IV) Air Strippinga) This method is used to remove ammonia nitrogen (NH4 – N)

from effluent.b) The design features shall depend on the required level of nitrogen

removal with the critical parameters being tower packing, quantity of air supply, air and liquid temperatures and process control measures.

V) Reoxygenationa) This method is used to increase the dissolved oxygen (DO) levels

in the effluent.

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b) The different types of reoxygenation systems are cascade, reoxygenation and mechanical reoxygenation

c) Cascade reoxygenation is achieved using on the hydraulic design of structures, such as, weir overflows, flumes, spillways, etc.

d) Mechanical reoxygenation is achieved using mechanical equipment such as surface aerators, jet diffusers or diffused air (coarse, fine bubble, etc.)

e) Design of structures or mechanical equipment is based on the amount of DO required for the effluent.

VI) Maturation pondsa) Pond systems are normally not encouraged because it requires

large land area and the inherent difficulty in controlling algal growth. In special cases, where land is in abundance, the project proponent may choose to use this system.

Figure 5.21 Typical Roof Details for Covered Sludge Drying Bed



b) The different types of reoxygenation systems are cascade, reoxygenation and mechanical reoxygenation

c) Cascade reoxygenation is achieved using on the hydraulic design of structures, such as, weir overflows, flumes, spillways, etc.

d) Mechanical reoxygenation is achieved using mechanical equipment such as surface aerators, jet diffusers or diffused air (coarse, fine bubble, etc.)

e) Design of structures or mechanical equipment is based on the amount of DO required for the effluent.

(VI) Maturation ponds a) Pond systems are normally not encouraged because it requires large

land area and the inherent difficulty in controlling algal growth. In special cases, where land is in abundance, the project proponent may choose to use this system.

Figure 5.21 – Typical Roof Details for Covered Sludge Drying Bed

Section 6

Requirements for Ancillary Facilities

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Volume 4 149Sewerage Treatment Plants

6.1 Introduction

This section defines the minimum requirements of ancillary facilities to be provided at the sewage treatment plants. These requirements are crucial in ensuring the workability and operability of the plants.

6.2 Water Supply and Wash Water

Water shall be supplied to each site from standpipes and taps, to provide for sanitary cleansing of plant areas, personal hygiene, safety, fire fighting, process use and for equipment cooling and/or sealing. Water shall be connected to potable supply that provides a minimum pressure of 20 m head across the site. A ring main system shall be provided for all treatment plants larger than 5000 PE.

Each sewage treatment plant or sludge treatment facility shall be provided with water tank of at least 445 litre storage capacities or one day water usage or whichever is higher.

Double backflow prevention shall be provided in all cases. This is to prevent contamination of any potable water service, including the incoming supply line.

The water supply system shall be sized to meet the following cases:

i) Fire fighting demand as instructed by the local regulations and any essential plant water demands.

ii) All potentially simultaneous process uses, equipment uses and a for plant cleansing.

All water supplies and its installation (piping, tanks, air conditioning drainpipes, gutters and etc.) must be totally isolated from all potential contact of electrical system by means of total enclosure or suitably located the electrical system above flood level.

Where required, wash water shall be equipped with booster pump and where possible, obtain from reclaimed water.

Drawings submitted for approval shall indicate locations of water tapping point and piping layout. Approval for water tapping should be obtained from water authority for permanent water supply before submitting inspection form. All related document, such as water bills and transfer of ownership, to be submitted before final inspection.

Table 6.1 tabulates the minimum number and location of stand pipe required in a sewage treatment plant. Typical drawing of stand pipe are shown in Figure 6.1

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Table 6.1 Minimum Number of Recommended Water Stand Pipe and Location

Class of STP


Minimum Numbers Location

1 ≤1000 1 Inlet Works2 1001 – 5000 2 Inlet Works and Treatment Process Unit

3 5001 – 20 000 2 Inlet Works and Treatment Process Unit

4 >20 000 4 Inlet Works, Secondary Screen Area, Treatment Process Units and Dewatering Facilities.

Figure 6.1 Standard Details for Stand Pipe



Table 6.1 – Minimum Number of Recommended Water Stand Pipe and Location

Class of STP


Minimum Numbers Location

1 1,000 1 Inlet Works 2 1,001 –

5,000 2 Inlet Works and Treatment Process Unit

3 5,001 – 20,000

2 Inlet Works and Treatment Process Unit

4 >20,000 4 Inlet Works, Secondary Screen Area, Treatment Process Units and Dewatering Facilities.

Figure 6.1 Standard Details for Stand Pipe

6.3 Mess Facilities and Ablutions

All treatment plants shall have a minimum of one sanitary set consisting of a toilet and wash basin. Washing facilities, toilets and showers shall be provided for operators at all Class 3 and Class 4 plants with PE greater

608

76 648 76

800

648

800

76

76

100

Ø15 G.I PIPE

STAND PIPE

6.3 Mess Facilities and Ablutions

All treatment plants shall have a minimum of one sanitary set consisting of a toilet and wash basin. Washing facilities, toilets and showers shall be provided for operators at all Class 3 and Class 4 plants with PE



greater than 5000. Additionally, mess accommodation shall be provided at Class 4 treatment plants with PE greater than 20 000.

Guard house with water and power supply shall also be provided for plant more than 20 000 PE.

Figure 6.2 Typical for Administration and Mess Facilities Building



than 5,000. Additionally, mess accommodation shall be provided at Class 4 treatment plants with PE greater than 20,000. Guard house with water and power supply shall also be provided for plant more than 20,000 PE.

Figure 6.2 Typical for Administration and Mess Facilities

Building

Visitor’s / Staff Parking

Covered Porch

Manager’s /Engineer’s Office

Supervisor's OfficeReception Area General Office

Meeting /Briefing Room

WorkshopControl Room

Sample Reception& Preparation

FemaleToilet

PrayerRoom

General Store

Pantry

Eating Area

Clean Locker RoomRecreation Area

Dirty Locker Room

Toilet / Shower

Motorcycles / Operational Vehicles Parking

Note : The numbers on the layout correspond to the numbers in Table B.1.The layout is only for indicative purposes only and can be changed ( i.e. floor space and other arrangement)to suit the plant’s needs and requirements.

16

13

10

119

9 9

MaleToilet

7

7

6

1214

8

5

3

2

1 4

16

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Minimum internal floor area of mess facilities are 400 meter2. Approval from the Commission shall be sought if smaller floor area is to be provided. Typical arrangement of mess facilities is shown in Figure 6.2

6.4 Roads and Access

All-weather, surfaced roads shall be provided to permit access to all treatment plants. The roads must withstand a load of at least 15 tonnes. Such roads must also be constructed within the plant providing access to each process unit. The construction shall comply with Public Work Department requirement. Figure 6.3 and Figure 6.4 illustrate the typical section of road pavement and site road.

Figure 6.3 Typical Details of Road Pavement







Figure 6.4 Typical Road Section of Site Road

The on-site road shall be able to provide safe and convenient access for trucks or other machinery equipment used for maintenance purposes. The

40 THK. WEARING COURSE

60 THK. PREMIX BINDER COURSE

10 THK. SAND/QUARRY DUST

300 THK. CRUSHER RUN50 THK SAND

ROAD KERBROAD KERB

FALL



250 THK. ROADBASE

150 THK. SUB-BASE

FALL

4000

GEOTEXTILE MEMBRANE APPROVED BY ENGINEERS








The on-site road shall be able to provide safe and convenient access for trucks or other machinery equipment used for maintenance purposes. The



10 THK. SAND/QUARRY DUST

300 THK. CRUSHER RUN50 THK SAND

ROAD KERBROAD KERB

FALL



250 THK. ROADBASE

150 THK. SUB-BASE

FALL

4000

GEOTEXTILE MEMBRANE APPROVED BY ENGINEERS




The on-site road shall be able to provide safe and convenient access for trucks or other machinery equipment used for maintenance purposes. The minimum width of the road shall be 4 meter Where vehicles need to pass frequently or parking is required along the road, the minimum width shall be 6 m.

Corner of junction for perimeter internal road for tankers or trucks access shall have a minimum inside radius of 6 meter. Inside radius for perimeter road not intended for tankers or trucks access shall be not less than 4 m.

Cul-de-sac at the end of roads shall be provided with turning area reserve of not less than 9 m.

Where roads for maintenance vehicles or machineries are not required, concrete or hard surfaced walkways of at least 900 mm width shall be provided between each process unit. Concrete hardstanding area can be laid where storage bins are located. The use of steps shall be avoided, where possible.

Where the ingress or egress of the treatment plant is near a junction of a public road, an adequate acceleration and deceleration lane must be made available between the access road and the junction for vehicles to safely enter and leave the treatment plant.

Vehicular access shall be provided to all unit processes that require daily operation and maintenance.

6.5 Drainage

The area of the treatment plant shall be adequately drained and this shall be arranged to prevent surface water run-off from entering the process units.

Any cleaning or maintenance process wash water must be returned to the inlet works via a separate drainage system.

External drainage facilities must be provided for treatment plant along the slope area. Cut off drainage at the entrance must also be provided.

Treatment plant platform level shall be designed above flood level. If the treatment plant is located in a flood prone area, flap gate shall be provided to avoid back flow from the river/ main drain. The plant hydraulic must be designed properly to ensure the discharge head is adequate to open the flap valve at any circumstances.

Volume 4



154

The effluent discharge shall be directed to the main drain or river to avoid discharging effluent into a drain within the residential area. Discharge to a retention pond is not allowed unless prior approval has been granted.

The receiving drain/watercourse shall have sufficient capacity to accept the run-off from the plant as well as the effluent discharge from the treatment plant.

6.6 Fencing and Security

The boundary of a treatment plant, pumping station and/or sludge treatment facility shall be secured by 3.0 meter high fence. The perimeter fence shall have an entrance by double gates or sliding barrier to allow access of maintenance vehicles. The gates shall be secured by padlocks and shall comply with the requirements of the Commission. Where the treatment plant is situated in a building, access to the plant must be secured.

The fence shall be 2.4 meter solid wall with three strands of 0.6 meter high barbed wire. Typical details of the fence are given in Figure 6.5, 6.6, 6.7 and 6.8.

STP project proponent is required to provide adequate warning/safety and the Commission signboard before handing over the sewerage system to the Commission.



Figure 6.5 Typical Drawing of Brickwall Fencing and Gate



Figure 6.5 Typical Drawing of Brickwall Fencing and Gate

1 5 0

2 4 0 06 0 0

300

042

0021

00

XX

XX

XX

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x 63

x 6

3 T

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Volume 4



156

Figure 6.6 Brickwall Fencing

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PIN

SW

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ACH

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BY

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x 6m

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3 S

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AT

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m R

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HK

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Figure 6.7 Precast Fencing

AT

3m IN

TERV

ALS

230

x 23

0mm

PRE-

CAST

CO

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5mm

TH

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ATT

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OA

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300

63 x

63

x 6m

m M

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DET

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230

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PRE-

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Volume 4



158

Figure 6.8 Masonry Fencing



Figure 6.8 Masony Fencing

B

NO

TE :-

1. F

OU

ND

ATI

ON

AS

PE

R T

HE

DE

SIG

N O

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NG

INE

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ALL

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ON

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SE

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US

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A-A

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B-B

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m B

ON

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1 N

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0mm

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BE

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BLO

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390m

mx1

90m

mx1

14m

m F

ULL

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1 N

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OR

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EIN

FOR

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ME

NT

390m

mx1

90m

mx1

90m

m B

ON

D B

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M B

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m x

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x 1

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m B

ON

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EA

M B

LOC

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390m

mx1

90m

mx1

90m

m F

ULL

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ME

NT

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IT P

INS

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INTI

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1.) A

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XP

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ED

WA

LL S

HA

LL B

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AIN

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WIT

H O

NE

UN

DE

RC

OA

T

OF

AP

PR

OV

ED

RE

SIS

TIN

G P

RIM

ER

SE

ALE

R A

ND

TW

O C

OA

TS O

F

AP

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R R

ES

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NT

EM

ULS

ION

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2.) T

WO

BA

ND

S O

F IW

K'S

CO

LOU

R W

ITH

OV

ER

ALL

HE

IGH

TS

O

F 40

0mm

SH

ALL

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PA

INTE

D O

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XTE

RIO

R F

AC

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F TH

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ALL

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3.) C

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UR

STA

ND

AR

DS

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.) IN

TER

IOR

/EX

TER

IOR

WA

LL

B.)

BA

ND

S -

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(P

AN

TON

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00C

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EQ

UIV

ALE

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- GR

EEN

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354

C) O

R E

QU

IVAL

ENT

SIR

IM C

ER

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CA

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CH

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E

63 x

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x 6m

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LEW

ITH

3 S

TRA

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S O

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ARB

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WIR

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- DU

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STE

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OR

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FIN

ISH



6.7 Beautification Zone and Landscape

Treatment plants shall be effectively and visually screened by a beautification zone within the treatment plant site of not less than 2 m wide, on which selected species of trees and shrubs can be planted. In congested or difficult locations, the Commission should be consulted on these requirements.

Premix or Paved area shall be provided at this zone for all class 1 treatment plants with loading equal or less than 1000 PE or where necessary.

6.8 Stores and Workshops

All Class 4 Treatment plants that exceed 20 000 PE and have a pump station within the premises shall be provided with an active store and workshop.

6.9 Spares

All mechanical units shall be provided with an adequate reserve supply of critical spare parts. A list of proposed spare parts should be forwarded for approval when detailed designs are submitted for verification and approval.

All parts recommended by the manufacturer to be provided with spares shall be so delivered at the stage of final inspection. Notwithstanding that, all parts with a life span of 3 years or less shall be provided with spares

Typical spare parts requirements are provided in Table 6.2. Spare parts shall be obtained from the original manufacturer of the equipment and shall be packed and protected for storage to BS1133 requirement.

A set of special tools if required and specific to an equipment including lifting tackle and greasing equipment necessary for the maintenance, repair, testing and overhauled of the equipment shall be supplied together with the spares at the stage of final inspection.

Volume 4



160

Table 6.2 Spare Part

No. Equipment Spare Parts Quantity

1. Pumps:Raw Sewage SubmersiblePumps.Grit Pumps.Feeding Pumps.RAS Pumps.Sludge Pumps.Effluent Pumps.

Bearingo-ringoil sealmechanical sealwear ringImpeller (for 3 or more pump of similar model)(see Pumps, Motors, Drives)

one setone setone setone setone setone setone set, whichever parts is relevant

2. Motors (Electric): Bearingo-ringoil sealmechanical seal

one setone setone setone set

3 Drivesa)Direct Coupleb)Chain

c)Belt

gear bearingchainsprocketV-belt

one setone setone setone set

4 Mechanically Raked Screens

ChainChain linkGear sprocket(also see Motors, Drives)

one setone setone setone set, whichever parts is relevant

5. Diaphragm Pump diaphragm one set6. Progressive Cavity

(Mono) Pumprubber stator one set

7. Blowers (see Motors, Drives) one set, whichever parts is relevant

8. Aerator:Diffused AirMechanical (surface, brush)

Diffusers(see Motors, Drives)

10% of total numbersone set, whichever parts is relevant

9. Scraper rotating collectorswheel(see Motors, Drives)

one setone set per clarifierone set, whichever parts is relevant

10. Conveyor (see Motors, Drives) one set, whichever parts is relevant



Table 6.2 Spare Part (continued)6.10 Yard Lighting

No. Equipment Spare Parts Quantity

11. Filter Press oil seal for hydraulic pumpmembrane cloth

one setone pair out of every five pair of plates

12. Belt Press oil seal for hydraulic pumpBelt

one setone set if the STP has only one press

13. Centrifuges (see Drives) one set, whichever parts is relevant

6.10 Yard Lighting

Effective yard and building lighting systems shall be incorporated within the treatment plant site in order to provide sufficient illumination for operation and maintenance schedules to be carried out during day and night periods. In addition, the entire treatment plant site shall have sufficient street lights and perimeter lights for various operations, safety and security reasons.

Compound lighting shall be provided at every 50 m interval for all manned and security plants. However, sufficient lighting is required at the strategic location such as entrance gate, inlet works and necessary areas. Refer to Table 6.3.

All lighting shall be accessible for maintenance / removal. Typical details of compound lighting are shown in Figure 6.9.

Table 6.3 Numbers of Unit and Location of Compound Lighting

Class of STP


Minimum Numbers

of UnitLocation

1 ≤1 000 1 Inlet Works or Entrance

2 1001 – 5000 2 Inlet Works and Treatment Process Unit

3 5 001 – 20 000 4Every Internal Corner of STP boundry and nearby to Inlet Works, Treatment Process Unit and Sludge Treatment

4 > 20 000 50 meterEntrance, Inlet Works, Mess Building, Process Treatment Unit, Secondary Treatment Unit and Sludge Treatment.

Volume 4



162

Figure 6.9 Typical Details of Compound Lighting



Figure 6.9 Typical Details of Compound Lighting

6.11 Sampling Facilities Suitable sampling facilities shall be provided (preferably in the form of an open chamber) within the boundary of the STP to allow representative samples to be taken safely by one person. For treatment plants up to 20,000 PE, sufficient space shall be allowed for proper preparation of samples to be taken away to central laboratories for further testing and analysis. The sampling area shall contain sufficient bench space and storage space for samples. For treatment plants greater than 20,000 PE, the sampling area shall be provided in accordance with MS 1228. Access ladder shall be provided for sampling facilities where necessary. Internal surface area for sampling point shall be tiled with clear coloured tiles

6.12 Auto Restart Facilities All electrical equipment shall be fitted with auto restart facilities for quick re-operation in the event of failure of power facilities.

105

105

670

250

290

STANDARD GALVANISED STREET LAMP POST

6000

LAMP POST

FRONT VIEW

SIDE VIEW

6.11 Sampling Facilities

Suitable sampling facilities shall be provided (preferably in the form of an open chamber) within the boundary of the STP to allow representative samples to be taken safely by one person. For treatment plants up to 20 000 PE, sufficient space shall be allowed for proper preparation of samples to be taken away to central laboratories for further testing and analysis. The sampling area shall contain sufficient bench space and storage space for samples. For treatment plants greater than 20 000 PE, the sampling area shall be provided in accordance with MS 1228. Access ladder shall be provided for sampling facilities where necessary. Internal surface area for sampling point shall be tiled with clear coloured tiles

6.12 Auto Restart Facilities

All electrical equipment shall be fitted with auto restart facilities for quick re-operation in the event of failure of power facilities.



6.13 Safety Facilities

Safe access and walkways shall be provided at all process units and equipment (valves, penstocks, aeration tanks, etc.) that require service and maintenance. Safety handrails shall also be installed at walkways and other working areas with a fall greater than 2 m. Typical details of hand rail are shown in Figure 6.10

All chemical storage facilities shall be provided with a safety shower and eyewash as well as appropriate warning signs. Liquid chemical storage facilities shall be bund. Access to the area shall be restricted using lockable doors/gates.

Provision for fire detection, alarm and fire fighting equipment shall be complying with the latest requirements in the Uniform Building Bylaws, the Institute of Electrical Engineers (IEE) guidelines and other statutory requirements.

All tanks shall not exceed 1.2 m above ground.

Stair case and ladder exceeding 1.2 m shall be provided with handrail

All plants located adjacent to earth slopes shall be provided with proper slope protection structures. The slope protection design must be certified by Qualified Professional Engineer.

6.14 Doors

All external doors shall be of weather proof and suitable for out-door installation.

Door with sufficient width for the manoeuvre of equipment shall be provided at the building of pump station, blower room, etc. For opening more than 4 m wide or 5 m high, motorized roller shutter shall be provided complete with manual over-ride button, which enables it to be operated during power interruption.

6.15 Fire Hydrant

For treatment plants above 20 000PE, fire hydrant shall be provided complying with the requirements of Jabatan Bomba.

Volume 4



164

6.16 Power Supply

Power supply shall be provided to each plant from the approved source. Drawings submitted for approval shall indicate the locations of electrical power tapping point and schematic layout plan. Approval for power supply tapping should be obtained from relevant authority for permanent power supply before submitting inspection form. All related document, such as electrical bills, transfer of ownership: to be submitted before final inspection. Requirement of power shall be finalised prior to obtaining design approval

Requirement of incoming permanent power supply shall be inline with Section 4 this Volume.

6.17 Internal Sanitation (Toilet)

All plants shall be provided with toilet. The toilet shall consist of water tap, water closet, shower and wash basin. The area for toilet shall comply with Uniform Building By Laws. Toilet to be located beside the control panel building. Toilets can also be located in the mess or office building.

6.18 Lifting Requirement

Safe lifting weight in unrestricted area is 16 kg. For heavier objects and/or very tight locations, provision of crane or access for truck mounted crane to be made.

Lifting requirements are as follows:

- Weight < 16 kg: Manual lifting- 16 kg ≤ Weight ≤ 250 kg: A davit or ‘A’ frame shall be arranged

to allow items lifted by using manual chain hoist to be projected on a 1.2 m truck tray and positioned at 2 m above road level. In the pump station, motorized hoist is required for lifting weight exceeding 100 kg.

- Weight > 250 kg: A gantry with motorised hoist shall be arranged to allow items to be projected on a 1.2 m truck tray and positioned at 2 m above road level truck tray.



Lifting equipment shall be subjected to DOSH approval standards and guidelines.

Safe Working Load with approved method of installation shall be rated and printed for all lifting facilities. Height and lifting method must be considered in the design for Safe Working Load of lifting facilities.

All portable motorised hoist shall be of 230 V operating voltage and fixed electrical hoist shall be of 415 V operating voltage.

All fixed 3 axis type gantry shall come with additional safety features such as travel stop limit switch, hoist over run limit switch, slow & fast speed mode and emergency stop (for all type of hoist).

All fixed type outdoor lifting facility futures shall comprise of hoist parking bay with shade. All fixed type lifting facility shall come with working platform and excess ladder.

Typical drawings of lifting davits and A-frame lifting facilities are shown in Figure 6.11 and Figure 6.12.

6.19 Ventilation

Ventilation is the process of letting in outside air into a space so that it mixes with the inside atmosphere to dilute contaminants and replenish oxygen. The purpose of ventilation in a sewage treatment plant is to provide a comfortable and safe working environment for all plant personnel.

Hence proper ventilation shall be provided as a mean of providing sufficient fresh air and reducing poisonous or explosive gases in enclosed or semi-enclosed spaces where access to human is allowed. Ventilation can be achieved naturally or mechanically:

• Natural ventilation uses the force of nature such as air currents, breezes, thermal gradients and pressure differences to move air in and out of the space.

• Mechanical ventilation uses fans and blowers to force air through space. It is also sometimes called forced ventilation.

Particular requirements are:

a) Ventilation shall be intrinsically safe with respect to explosive gases (such as methane) where such gases may be present.

b) Ventilation shall be designed to deal with the different densities of the various gases.

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c) Ventilation fans shall be located outside the enclosed space to induce forced air into the plant. Intake locations shall be such that only fresh air is drawn into the system and not air recirculated from the exhaust.

d) Mechanical ventilation shall be used if the system is required to remove contaminants.

e) Ventilation exhaust shall be directed to a suitable location for discharge and it shall not be adjacent to the intake point.

f) Ventilation at rooms where heat generation may take place must be adequate to dissipate the heat generated to ensure a comfortable making ambient for the equipment and the operator.

g) Noise levels associated with operating fans and blowers, particularly in a confined space, shall conform to the requirements in Section 4 of this Guidelines and other stationary requirements.

h) Optimise recurring cost for operation, maintenance and replacement.

i) Regular testing and inspection of the equipment

j) Compliance with the suggested ventilation requirements. Table 6.4 presents some commonly used values for ventilation rates in typical enclosed spaces of a sewage treatment plant: -



Table 6.4 Common ventilation rates

SpaceMinimum Ventilation Rate

(Air Changes/hour, ac/hr)Remarks

Wet-Well 30 intermittent12 continuous

Use 100% outside air. Step up to 24 ac/hr if hazardous gases are detected. Consider odour control, where warranted

Dry-Well 30 intermittent12 continuous

Grit Removal/Screen Area

30 intermittent12 continuous

Same as wet well

Digester Gas Control Room

30 intermittent

12 continuous

Same as wet well

Sludge Gas Compressor Room

30 intermittent

12 continuous

Same as wet well

Enclosed Grit Loading Areas

30 intermittent

12 continuous

Same as wet well

Enclosed Primary Sedimentation Tanks

30 intermittent

12 continuous

Same as wet well

Scum Concentration Tank

30 intermittent

12 continuous

Same as wet well

Chlorine and Sulphur Dioxide Rooms

60 intermittent

12 continuous

Hazardous areas, toxic fumes, floor level exhaust required. Interlock fans with manual switches located at each entrance. Also interlock fans with chlorine and sulphur dioxide detection. Use 100% outside air

Filter/Dewatering Area

12 continuous Consider odour control for exhaust air from dewatering area, where warranted

All other enclosed unit processes not mentionedelsewhere

30 intermittent

12 continuous

In particular at blower room, high tension room, low voltage room, switchboard and control panel rooms, where there are tendency of heat generation

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k) An audible and visible warning shall be provided at all entry points. This shall automatically operate if the fan fails.

l) Where natural or forced ventilation is provided, it shall be installed in such a manner so as to avoid any ingress of water due to rain or other sources.

m) In areas with routine entry by personnel, the ventilation strategy shall emphasize adequate control of contaminants and the ventilation system shall be continuously operated.

6.20 Process Water

The designer is encouraged to provide recycle water facilities from the treated effluent. The recycle water can be utilised for cleaning and landscaping purposes.

6.21 Aesthetic

The structure of a treatment plant shall blend with the surrounding development to improve the aesthetic value of the area. Roof, structure wall or brickwall fancing can be designed with other than conventional finishing.

6.22 Close Turfing

Unpaved area within the STP reserve shall be turfed with close turfing. The type of grass must be “cow grass”. For slope area, turf must be pegged to avoid grass wash away during water run-off.

6.23 Standard Roofing and related requirement

Roof for control panel shall be of flat roof and shall be installed with water proving material on the final layer. The slope of flat roof shall be 1: 20 and gutter shall be provided.

However, for the aesthetic purpose Pitch type roof may be provided. The slope shall be 30 degree from horizontal. Suitable material for roof such as roof tile is recommended.

The design of roof shall be considered from the following:

i) Suitable material for roof (flat or slope) including colour

ii) Adequate air for ventilations

iii) Enough heights for lifting facilities



iv) Enough heights for access and headroom

v) Type of insulation

vi) Acoustic treatment where applicable

6.24 Painting

Painting shall include all plant and machinery inside buildings, including pipework, grating, handrailing, internal walls below ground level and all metal work including machinery.

The conduits and piping shall be appropriately named and labelled indicating flow directions and painted with the following colour codes for easy identification:

Chlorine line - yellow with double green bands

Compressed air line - green

Fuel gas line - orange

Potable water supply line - blue

Raw sewage line - black

Final effluent line - grey

Sludge line - brown

Non-potable water line - blue with double black bands

Other disinfectant lines - yellow with double red bands

Biogas line - yellow

The labels shall be stencilled on the piping in a contrasting colour with the colour coded bands, if any, located at appropriate and strategic points.

Colour codes selected for general equipment, building and others items in a sewage treatment plants shall be adhered to colour standards as detailed in Table 6.5. The types of paint and surface preparation used shall be as recommended by the paint manufacturer.

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Table 6.5 Painting System Index – Colour Standards

Item Colour Equivalent Colour Guide

General Equipment including motors (unless come with the original manufacturer approved colour code)

Dark Blue Dulux Regal Blue 0013

Par Mandarin Blue 0013

Penstocks/Valves/Manhole Covers Black Par Bituminous Black

Machinery Guards/Railings/Runways/Overhead Cranes/Lifting Davit

Yellow Dulux Lemon 2024

Par Golden Yellow

Switchboards Light Grey Dulux Pewter 695

Par Willow Grey 00A05

Fencing poles/Gates Green Dulux A365-13449

Par Green 3666

Building and Walls – Exterior Grey(Weathersheild)

Dulux BS 00A05-10235

Building and Walls - Interior White

Fencewall – Interior and Exterior Grey Dulux BS 00A05-10235

Floors - Concrete Interior Green Leigh Green 3666

Building Stripes Green Dulux A910-13448

Par Green 3666

Blue Dulux A910-11482

Par Blue 2686

Indah Water Logo (where applicable) Indah Water Green

Dulux A365-13449Par Green 1006

Indah Water Blue

Dulux A365-11483Par Blue 1007

Notes:The above painting requirements are not applicable to stainless steel, aluminium, galvanised metal surfaces except where necessary to comply with statutory health and safety requirement.



Figure 6.10 Typical Detail of Guard Rail



Figure 6.10 Typical Details og Guard Rail

FLAT BASE

550

1100

TUBULAR STANDARDS

21/41

100 33

SIDE PALM BASE

TYPICAL RUN OF HANDRAIL AS

VIEWED FROM WALKWAY SIDE

TYPICAL RUN OF HANDRAIL AS

VIEWED FROM WALKWAY SIDE

ROUND BASE

TUBULAR STANDARDS

1100

550

TRIANGULAR BASE

21/41

100

12

100 36

150-

250

150-

250

1100

550

550

3000 C/C 3000 C/C

DETAIL OF HOT DIPPED G.I. RAILING

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Figure 6.11 Typical Detail of Lifting Davit

Figure 6.12 Typical Detail of A-Frame Lifting Facilities



6.11 : Typical Detail of Lifting Davit

Figure 6.12 : Typical Detail of A Frame Lifting Facilities

30°

900

177

545

0

75

PLAT THICKNESS 10

50

50

25

25

DETAIL À'

SAFE WORKING LOAD TO BE INDICATED

SIDE VIEWLIFTING DAVIT

25

OD = 118

OD=98

630

20

SECTION

FL FL

20

NOTE : DEPTH OF SLEEVE SHALL VARIOUS WITH HEIGHT OF POLE ACCORDINGLY

LIFTING DAVIT26

0

250

120

10

6 FILLET WELDED

DETAIL À'

FRONT VIEW

1800

2160

203x133x25Kg/m UB

300x300x12 PLATE BOLTED TO CONCRETE

180

315

2340

A-FRAME WITH I-BEAM

TO PROVIDE WITH ROLLER OR FIX TO THE CONCRETE FLOOR (TO SYSTEM SUPPLIER DESIGN)

SIDE VIEW

203x203x46Kg/m UB


203x133x25Kg/m UB

1200

1500

2340


A-FRAME WITH I-BEAM



6.11 : Typical Detail of Lifting Davit

Figure 6.12 : Typical Detail of A Frame Lifting Facilities

30°

900

177

545

0

75

PLAT THICKNESS 10

50

50

25

25

DETAIL À'

SAFE WORKING LOAD TO BE INDICATED

SIDE VIEWLIFTING DAVIT

25

OD = 118

OD=98

630

20

SECTION

FL FL

20

NOTE : DEPTH OF SLEEVE SHALL VARIOUS WITH HEIGHT OF POLE ACCORDINGLY

LIFTING DAVIT

260

250

120

10

6 FILLET WELDED

DETAIL À'

FRONT VIEW

1800

2160

203x133x25Kg/m UB


180

315

2340

A-FRAME WITH I-BEAM


SIDE VIEW

203x203x46Kg/m UB


203x133x25Kg/m UB

1200

1500

2340


A-FRAME WITH I-BEAM

Section 7

Special Requirements

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7.1 Temporary Treatment Plants

7.1.1 Definition

Temporary treatment plants refer to STP that are built to operate on a temporary basis. The sewage will eventually be diverted to a centralised sewerage system. After then, the temporary treatment plant will be decommissioned.

There are 2 categories of temporary treatment plants:

Category 1 For temporary treatment of sewage during the upgrading of an existing

sewerage treatment facility

Category 2 For temporary treatment of sewage during initial stage of a new housing

development where it is not feasible to construct a plant of ultimate capacity during initial stage or it is located within the catchment of a centralised sewerage system.

7.1.2 Category 1: Temporary Treatment Plant for Upgrading of Facilities

During the upgrading of an existing treatment plant, the sewage flows into that plant shall be directed to a temporary treatment plant for treatment before discharge. The treatment process of the temporary plant shall be designed and calculated based on: the duration of the project, total existing flow and the compliance requirements. The temporary treatment shall be monitored at regular interval. Approval from the Commission and DOE must be obtained prior any direct discharge of the untreated sewage into the receiving watercourse. The temporary treatment plant shall be located within the compound of the existing site. The temporary treatment plant shall not be built on other site area unless approval is granted by the Commission

7.1.2.1 Compliance Standards for Category 1 Temporary Treatment Plants

Category 1 temporary treatment plant shall comply with the requirements as stipulated in this Guideline and shall be operated and maintained to the satisfaction of the Commission and the Director General of the Department of Environment (DOE) at all times.

The temporary treatment plant shall be designed to comply with the following minimum effluent requirements:

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a) Standard B for STP located downstream of water intake points and non-water catchment zones

b) Standard A for STP located upstream of water intake points

The above levels shall be interpreted as ‘absolute’ pollutant levels. Final effluents will be monitored over the life of the temporary plant. A license to contravene shall be obtained before the construction of any temporary plant and the commencement of any upgrading works.

The temporary plant shall incorporate provisions to minimize adverse impacts such as visual, noise, odour nuisance etc. to the surroundings.

7.1.2.2 Process Requirements for Temporary Treatment Plants

Alternative or innovative designs may be used for temporary plant to meet the general design compliance as stipulated above.

Unit processes within the temporary treatment plant can be designed to absolute standards. For example, a Standard A the effluent level of temporary treatment plant of this category can be designed to 20 mg/l BOD and 50 mg/l SS.

Materials for construction can be of semi-permanent installation such as fiberglass tanks, mild-steel with epoxy coat, etc.

7.1.2.3 Operation of Temporary Treatment Plants

During the upgrading of an existing plant, the project proponent shall appoint a class license to operate and maintain the temporary plant. If the upgrading contractor is a licensed operator, they may be appointed as the operator of the temporary plant.

7.1.3 Category 2: Temporary Plants for New Housing Development

I) Multiple Phases Hosing Development

Temporary plant shall be provided for multiple phases housing development where it is not feasible to construct a plant with ultimate capacity during initial stage.

STP reserves must be located as far as practicable from habitable buildings. The needs of a temporary plant in a multiple phases housing development project depend on phases of development, size of each development phase, location of initial development and duration of the phase lag and entire development plan.



The project proponent will construct a temporary treatment plant in compliance with the following criteria:-a) Temporary plant will be decommissioned by the developer within

time frame agreed between the Commission and the developer.b) Implementation program for ultimate plant is confirmed in

accordance to an approved catchment study.c) All temporary plant shall remain as private plant and shall be

operated and maintained by a licensed operator appointed by the project proponent.

(II) Future Connection to Centralised STP

This applies to a catchment where implementation program to construct a centralised STP is approved but the completion date could not meet the project proponent’s needs. Under such circumstances, the project proponent may be allowed to build a temporary treatment plant.

7.1.3.1 Provision of Land for Temporary Treatment Plants

The owner will be required to allocate land within the housing development for the construction of all temporary works. However, the site of the temporary treatment plant shall not be located on future public amenities land.

The project proponent of the temporary treatment plant will be required to construct the temporary sewer reticulation within the development to convey sewage to the temporary treatment plant. At the same time, the project proponent must also construct the permanent sewer reticulation for the connection to the permanent plants or the centralised sewerage system.

7.1.3.2 Compliance Standards for Temporary Treatment Plants

This category of temporary treatment plant shall comply with the requirements as stipulated in this Guideline. The plant shall also be maintained to the satisfaction of the Commission and the Director General of the Department of Environment (DOE) at all times.

The temporary treatment plant shall be designed and maintained to comply with the following minimum effluent requirements:

a) Standard B for STP located downstream of water intake points and non-water catchment zones.

b) Standard A for STP located upstream of water intake points.

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7.1.3.3 Process Requirements for Temporary Treatment Plants

Temporary treatment plants shall be designed to the requirements set out in Sections 3, 4 and 6 of this Volume.

An alternative design may be considered for the temporary treatment plant that will be decommissioned within time frame agreed between the Commission and the developers.

Materials for construction can be of semi-permanent installation such as fiberglass tanks, mild-steel with epoxy coat, etc.

Filter systems may use refurbished filter material that meet the relevant standards. However, other equipment used within the works shall be new. Second-hand equipment is strictly prohibited.

7.1.3.4 Operation of Temporary Treatment Plants

Temporary plant shall remain as private plant. The owner must appoint a licensed operator to operate and maintain the plant.

Temporary treatment plants shall strictly comply to the requirements as stipulated by this Guideline and shall be operated to the satisfaction of the Commission and the Director General of DOE at all times.

Temporary treatment plants shall be designed and constructed so as not to present any nuisance in terms of odour, noise, safety and visual impact to the nearby community.

7.1.3.5 Ancillary Requirement of Temporary Treatment Plants

Temporary treatment plants shall be provided with proper security fencing in compliance with Section 6 of this Volume.

Adequate access roads and drainage shall be provided.

Landscaping of treatment plant shall be provided for better aesthetic value surrounding the plant.



7.2 Treatment Plants Located Within Buildings

7.2.1 Introduction

The installation of treatment facilities within buildings whether occupied or not, including basements of buildings, are not desirable and will not normally approve. Every effort must be made to come up with an alternative site or an arrangement to connect to a public system.

Owners must resolve these issues at an early stage of the planning process. The Commission should be contacted early to establish if an alternative option is feasible.

If approved, such installations will be subjected to stringent service condition requirements for the following criteria:

a) Access

b) Ventilation

c) Electrical requirements for lighting system

d) Noise control

e) Process type

f) Inlet works

g) Pre-treatment

h) Confined space safety

i) Odour Control

j) Discharge systems

k) Flood mitigation measures

l) Operation and maintenance

m) General safety and health

n) Sludge handling

o) Sanitary and plumbing facilities

p) Fire Fighting Equipment

Treatment plants within buildings will be considered as private treatment plants subject to eventual phasing out and replacement by a centralised system.

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7.2.2 Specific Guidelines and Requirements

The specific guidelines and requirements for the criteria specified in 7.2.1 are listed below.

I) Access

a) Vehicle access must be provided from the nearest public highway.

b) Parking space for a desludging and service vehicle must be within operating range.

c) Access must be continuously available and unobstructed.

d) Accessible to water and electricity supplies.

e) Sampling point to be available for final effluent.

f) Allowance must be made for installation and removal of equipment.

g) Provision must be made for lifting of heavy equipment.

h) Suitable arrangements must be made for service and repair of equipment.

II) Ventilation

Ventilation design shall be in compliance with the requirements in Section 6 and the specific requirements listed below:

a) Suitable system must be provided to address poisonous, explosive and lack of oxygen conditions.

b) Separate and independent (from the basement) ventilation must be provided for the confined spaces.

c) Ventilation shall be of forced mechanical type.

d) Ventilation must be intrinsically safe with respect to explosive gases such as methane.

e) Ventilation must be designed to deal with the different densities of the various gases.

f) Ventilation fan must be located outside the enclosed space to induce forced air into the plant. Intake locations shall be such that only fresh air from outside the building id drawn into the system and not air re0circulated within the building.

g) Ventilation exhaust must be directed outside the building for discharge.



h) Ventilation air exchanges shall be as follows:i) Intermittent: Minimum of 30 complete air changes per

hourii) Continuous: Minimum of 12 complete air changes per

houri) A backup fan must be provided in the event of duty fan failure

and must be automatic on entry.j) A petrol driven generator with an auto restart facility must be

provided to continually operate the ventilation system in the event of power failure.

III) Electrical Requirements for Lighting System

a) Only high-intensity, low-voltage discharge lamps to be used for floodlighting of plant area during operation and maintenance.

b) The lighting and electrical equipment must be both vapour and explosion proof.

c) A separate housing must be provided for electrical controls to prevent electrical sparks from coming into contact with flammable and explosive gases.

d) All electr ical equipment must be water proof against submersion.

e) Standby generators must be provided to allow the plant to operate independently of the mains supply.

IV) Noise Control

a) Adequate dampening of noise must be provided to meet minimum stipulated requirements by the local Building By-laws, DOE and/or other regulatory bodies. Silencers and acoustic enclosures shall be provided where required to achieve the stipulated noise level reduction.

b) Noise control measures shall be implemented to control the generated noise level to below 65 dB at a distance of 2 m from the boundary of the housed noise source.

c) General noise levels (measured in decibel units) must also be measured 10 m from any point of the plant site within the nearest public space or occupied space or both to an acceptable level stipulated by the regulator.

d) Enclosures used to achieve these noise reductions shall permit ready access to equipment for routine maintenance. Adequate air ventilation shall be provided to allow cooling of the air inside the enclosure to prevent over heating of the equipment/motors.

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V) Process Type

The type of treatment process must be limited to systems that are easy to operate and maintain for reasons of:

a) Lower sludge yield and more stable sludge characteristics b) Lower operational and maintenance requirements

VI) Inlet Works

The design shall incorporate some means of controlling the influent velocity to prevent:

a) Excessive wear due to scouring effectsb) Excessive head loss in the inletc) Uncontrolled overflow of raw sewaged) Release of sewer gases

VII) Pre-treatment

a) The design must include a macerator to i) reduce toilet waste and large solids into smaller and finer

particles, ii) reduce the quantity of screeningsiii) improve the ease of handling.

b) Screening must be provided at 10 to 12 mm clear spacing to remove fine particles.

c) A combined grit and grease removal system must be provided.

VIII) Confined Space Safety

a) Operators must:i) attend a recognised confined spaces training course, ii) obtain training certificates, andiii) be certified competent to operate in such an environment.

b) Confined space areas within the plant site must be clearly identified before handover for operation.

c) Confined space areas must be demarcated and warning notices placed.

d) Confined space procedures must be established and followed by operatives.



e) The following must be provided: i) Rescue sets of breathing apparatusii) Gas detection equipment, preferably electronic, and serviced

regularlyf) The design of the treatment plant shall be subject to a Hazard

and Operability Review (HAZOP) exercise to identify and reduce the potential risks under the following scenarios:i) Electrical failureii) Blockage of inlet and outletiii) Equipment failure including lighting and ventilation iv) Blockage of any pipeworkv) Flooding of external discharge pointvi) Failure of building drainage system

g) The consequences of such failures to operators may include:i) Flooding ii) Explosioniii) Drowning iv) Falling into open voidsv) Asphyxiavi) Poisonvii) Nausea

IX) Odour Control

a) Isolate odorous gases from general ventilation exhausts by containing identified odour generating sources with a separate local exhaust system.


c) The local exhaust odorous air shall be conveyed through well designed and balanced ductworks by a centrifugal fan to an effective odour treatment equipment.

d) Odour treatment equipment shall be selected such that odours be reduced to the lowest possible level and in compliance with the EQA.

e) The potential of odour generation, its impact and treatment, shall be considered in all aspects of design.

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X) Discharge Systems

Most basement plants will lie below the level of the running drain levels. Therefore, it is essential to:a) Provide an effluent collecting sump prior to pumped discharge.b) Provide a check valve at the end of the discharge pipe to prevent

the backflow from the monsoon drain to the treatment plant.c) Provide a 100% redundancy of the discharge pumping

capacity.

XI) Flood Mitigation Measures

a) Provision must be made for the isolation of the treatment plant from flooding by external sources.

b) A sump pump shall be provided.

XII) Operation and Maintenance Agreementsa) All treatment plants installed in basements of buildings must be

subject to an Operation and Maintenance Agreement. An example of the standard Operation and Maintenance Agreement is given in MSIG Volume 2.

b) All treatment plants located within buildings must be operated by a fully licensed operator and will be subject to periodic checks by the Commission to ensure compliance.

XIII) Occupational Safety and Health

a) All treatment plants shall be designed to comply with the Occupational Safety and Health Act, 1994. Properly designed treatment plants will enable the operator to safely handle the treatment plant throughout its design life. A brief summary of the contents of Act 514 is attached in Appendix A.

XIV) Sludge Handling

a) An aerated sludge holding tank shall be provided to keep the sludge from going septic

b) Permanent pipe work with proper coupling and isolation valve should be provided adjacent to the access gate for easy coupling sludge tanker’s hose of hose for during desludging of the sludge holding tank.

c) To provide sludge pump for desludging purpose.



XV) Sanitary and Plumbing facilities

a) To provide stand pipe for cleaning purposes. Waste water to be channelled back to the inlet of plant.

XVI) Fire fighting system

a) To provide appropriate fire fighting systems in accordance to Fire Department and other statutory requirements.

7.3 Fully Enclosed Treatment Plant

7.3.1 Definition

A fully enclosed plant is defined as a treatment plant that is designed such that their treatment unit processes are located within dedicated buildings.

A fully enclosed plant is to be equipped with additional features and requirements to minimize adverse impact to the surrounding environment.

Fully enclosed treatment plant shall comply with the following criteria:

a) Must be located within a dedicated sewage treatment site.b) Provide with appropriate architectural enclosures building.c) No unit processes shall be located outside the enclosed buildings/

architectural enclosures.d) Individual treatment unit process may be covered with a permanent

structure or housed in an enclosed building.e) Provide appropriate landscaping to adequately screen the treatment

plant from other developments in the vicinity.

Appropriate architecture style, landscaping, architecture surrounding the treatment plant and fencing type must be used.


When approved, fully enclosed treatment plants must comply with the general requirements set out in Section 3, 4 and 5 of this Volume and also specific requirements in this Section 7.3 for the following:

i) Provision of odour control

ii) Noise control and mitigation measures

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iii) Minimize visual impact

iv) Avoid aerosol effects

v) Enhance safety, health and operability

I) Odour Control

The potential for odour generation, its impact and treatment, shall be considered in all aspects of design. The range of odorous constituents in such biogenic odours is very wide and they include: hydrogen sulphide, ammonia, thiols and other organic sulfur compounds, amines, indole and skatole, volatile fatty acids and a wide range of organic compounds produced by anaerobic fermentation. Particular problems can be found at: Inlet works, primary tanks, secondary treatment, sites for transfer, storage and treatment of raw sludges and leakages. A separate local exhaust system, for containment and exhaust of odorous air to treatment, will isolate such odours from the general ventilation system.Odour treatment equipment shall be selected such that odour is reduced to the lowest possible level and in compliance with the EQA.Containment, exhaust and treatment shall be designed as an integrated package.

II) Noise Control

Adequate dampening of noise must be provided to meet minimum stipulated requirements by the local Building By-laws, DOE and/or other regulatory bodies. Silencers and acoustic enclosures shall be provided required to achieve the stipulated noise level reduction.

Noise control measures shall be implemented to control the generated noise level to below 65 dB at a distance of 2 m from the boundary of the housed noise source.

The general noise levels generated shall also be measured 10 m from any point of the plant site within the nearest public space and/or occupied space to an acceptable level stipulated by the appropriate regulators.

Enclosures used to achieve these noise reductions shall permit ready access to equipment for routine maintenance. Adequate air ventilation shall be provided to allow cooling of the air inside the enclosure to prevent over heating of the equipments/motors.



III) Aerosol Effects

Aerosol is defined as a suspension of colloidal particles in gases/ atmosphere. Aerosol control measures are important because aerosol affects the human respiratory system.

If uncontrolled, aerosol could present a health hazard to the operator and residents due to the reduced buffer zone around the treatment plant.

Screens, open channels and aeration tanks, where violent and turbulent actions are encountered, may release aerosol. The design of the treatment plant shall take into consideration any unit processes that are likely to emit aerosol and mitigating measures shall be undertaken to counter aerosol release to the atmosphere.

IV) Safety, Health and Operability

The design of a fully enclosed treatment plant shall address safety, health and operability aspects. The guidelines given for treatment plants located within buildings in Section 7.2 shall be followed.

7.3.3 Specific Requirements

I) Covers for Treatment Unit Processes

The purposes of these covers are to contain odour emission at source and to reduce visual impact.

The design requirements for treatment unit processes are outlined below.

a) Covers to contain odour emission shall be provided at all potential sources of odour generation for all unit processes located within the sewage treatment works.

b) Bins used for the storage of screenings and grit collected in the pre-treatment area shall be completely covered to reduce visual impact, odour and to keep vectors away. The designer shall provide further considerations on the size, type and method of emptying the bins.

c) Generally, all unit processes shall be covered or housed within a building enclosure. This shall include all pre-treatment units, aeration tanks, and sludge treatment and handling facilities. The only exception is the secondary clarifier.

d) The bin shall be located on a bunded, paved area adjacent to an access road to the treatment plant.

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e) The cover shall comply with BS EN 124 if subject to loading. It shall also be designed to meet the operating condition of the odour extraction system as well as the location and application appropriation.

f) If the cover is exposed to the environment, i) Plastic or fiberglass cover if used, must be manufactured

with UV inhibitor and will not warp or deform due to weathering effect.

ii) Metal covers if used, must have appropriate corrosion resistant coating in accordance to Section 4 of this Volume.

iii) Where chipping might occurs at the edge of the cover, stainless steel reinforcement frame on all sides of a plastic or FRP cover shall be provided.

g) Coatings for the concrete and steel shall include coal tar, vinyls and epoxies in accordance to Section 4.

h) Covers should be hinged and weigh less than 16 kg to enable lifting unaided. Beyond a cover weight of 16 kg, assisted lifting is required.

i) All unit processes with covers or are housed in a building for odour and visual impact reduction shall be provided with proper air extraction and air scrubbing system. These devices shall be safe to operate and maintain. Odour, noise and visual impact, and aerosol are the major components for consideration in the design of an enclosed wastewater treatment plant. Windows and access hatches that give the operator an extended and uninterrupted view of the treatment process are mandatory for all unit processes that are covered.

j) Covers shall be designed to allow for easy dismantling and easy access for cleaning of the enclosed plant.

k) The materials used for the cover structure depend on the type of cover selected and the characteristics of the odorous environment. In general, the materials shall be selected to provide durability, ease of maintenance, corrosion resistance and be relatively inexpensive. The three most common materials used for containing odours are concrete, aluminum and FRP. The design requirements for each of these are outlined below.i) Concrete

Concrete can support the greatest weight but limits the plant maintenance worker’s ability to remove the cover for major repairs. Concrete covers are subject to corrosion and should be treated with a protective coating, such as an epoxy resin.



ii) Aluminum

Aluminum covers provide the greatest tensile strength with the thinnest cross-sectional area and can be placed on a light weight frame. The lightweight nature and thin cross-sectional area of aluminum makes it easier to remove and store the covers during maintenance operations.

Aluminum covers are generally less expensive than FRP and concrete, but periodic maintenance in the form of an anodised coating is necessary to help prevent corrosion. The design of an aluminum cover shall consider the incompatibility of aluminum with concrete and other metals. If not, disintegration of the materials occurs and the structural integrity of the system could be jeopardized.

iii) FRP

FRP is light weight and generally can be removed by plant operator and stored during maintenance operations. FRP covers also offer resistance to corrosion, but require periodic maintenance with an ultraviolet inhibitor to enhance durability, particularly, if exposed to sunlight on a prolonged basis.

II) Ventilation system

Ventilation systems are required to supply fresh air for workers to work in a more comfortable environment and to minimise health and safety concerns.

All covered unit processes must have proper ventilation systems.

a) An exhaust ventilation system shall be provided with air distribution patterns that effectively purge work areas.

b) For waste areas that workers must enter, both blowing and drawing air shall be used to eliminate dead spots.

c) Areas designed for personnel entry must include relief systems to avoid overpressure conditions. Designers must estimate cover system leakage to determine fan capacity.

d) Force air ventilation systems should be inspected and tested periodically to ensure proper air flow and air distribution.

e) Ventilation of enclosed plants can be either intermittent or continuous. However, intermittent ventilation is not recommended because it has a lower degree of safety and more difficult to operate and maintain than continuous ventilation. Continuous ventilation is typically more expensive to operate because of higher electricity costs for running the blowers. Intermittent

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ventilation typically requires a higher rate of ventilation. For example, the wet well and grit removal facility requires 12 air exchanges for continuos ventilation versus 30 air exchanges for intermittent ventilation.

f) The requirement in Section 6 shall be refer for the design of exchange rate. If the work site is classified as a confined space, workers without proper respiratory equipment must not occupy spaces that cannot be ventilated to less than 25% of the permissible exposure limit (PEL) of the contaminant and less than 10% of the lower explosive limit (LEL). For example, hydrogen sulfide which is one of the most common contaminants in enclosed areas exposed to wastewater has a ceiling concentration of 30 mg/m3 (20 ppm).

g) Combustible alarms set at a percentage of the LEL and ventilation failure alarms should be installed in wet wells, screen rooms, or other enclosed areas where a volatile atmosphere could exist. These alarms must have both audible and visual indicators to alert workers that the area is now potentially dangerous as well as alerting those who are about to enter the problem area.

h) Before entering the enclosed plant, where there is potential for a hazardous atmosphere to exist, the operator and/or worker must be able to test for oxygen deficiency, and combustible and toxic gases or vapors.

i) Ventilation systems shall be designed on the basis that the potential odourous gases have been isolated and contained by the local exhaust system for odour control.

j) Ventilation design criteria for work space are as follows:

i) Avoid positioning supply and exhaust registers at equal elevations and on the same enclosure wall. This will prevent short-circuiting the ventilation system and creating dead zones (areas with no apparent ventilation or air motion).

ii) Equip the makeup air supply and exhaust registers with volume dampers to control the airflow rate. Makeup air supply should be less than what is exhausted to create negative air pressure within the enclosure.

iii) A duty and standby ventilation system are mandatory. The standby shall be 100% that of duty.

iv) An external visual indicator, such as green/red light, to be provided outside the enclosed plant to warn of ventilation systems failure.



k) The design of the ventilation system shall take into account the noise aspects. Generally, the design work shall include for sound insulating material, resilient mountings or other appropriate devices to ensure that the plant runs without noise or vibration in its final installed position. Noise level from machinery shall not exceed the level stipulated by the regulators.

III) Odour Control System

a) Isolate odorous gases from general ventilation systems by containment of identified odour generating sources with a separate local exhaust system.


c) Local exhaust rates for containment shall be designed to provide a negative pressure, prevent build up of toxic, corrosive or explosive gases and include provision for process air or air displaced by changes in the level of liquid inside the covered space.

d) The local exhaust odorous air shall be conveyed through well designed and balanced ductworks by a centrifugal fan to effective odour treatment equipment.

e) The overall performance of the odour control system shall comply with the requirements of the Department of Environment (DOE).

f) In situations where specific gases such as hydrogen sulphide and ammonia are significantly present, consideration shall be given for the installation of a pre-scrubber unit upstream of the main odour treatment equipment.

g) Effective odour treatment equipment to be a minimum 90% removal efficient.

h) Consideration must be given to the life span of the odour control system and associated costs in operating and maintaining such a system.

IV) Vent Stack

The vent stack shall at a minimum 5 m above ground level to ensure sufficient dispersion of air. Where the stack is located adjacent to a building, it should be located at least 1 m above the roof line of this building.

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V) Noise Level

All mechanical equipment that are likely to generate noise such as blowers, compressor and pumps, shall be acoustically isolated to ensure the noise generated are contained and reduced to below the levels stipulated by the regulators.

VI) Sludge Handling

a) Due to the compactness of the site, it is not conceivable to have sludge drying beds in an enclosed environment.

Instead, an aerated sludge holding tank shall be provided to prevent the sludge from turning septic. Sand drying beds (either covered or otherwise) are not an acceptable form of sludge treatment in an enclosed plant.

b) Permanent pipework with female coupling and isolation valve should be provided adjacent to the access gate for easy coupling of tanker’s hose during desludge of the holding tank.

VII) Treatment Process Type

It is preferred that treatment in an enclosed environment employs extended aeration activated sludge because it offers greater process stability and less potential for generating odours. However, other treatment processes warrant further considerations if proven that they have other distinct advantages in an enclosed environment.

VIII) Siting of Plant

a) The enclosed plant needs to be located away from driveways to allow for regular maintenance of the screens, grit and grease removal units and wet well of pump stations. If this is not possible, then bollards shall be erected to protect the workers while maintaining the plant.

b) Where plants are located within the premise of a private property, direct vehicle access is to be provided from the public road to the plant via a gate in the perimeter fence.

IX) Groundwater Conditions

a) Adequate provision must be made to resist the uplift of the structure due to hydrostatic ground water pressures. The side and bottom walls shall be designed to withstand the anticipated hydrostatic pressures.



b) The top of the plant shall be located at least 150 mm above the finished surface level to prevent the inflow of surface run off into the enclosed plant.

c) Good perimeter drainage is to be provided to ensure that the plant is not flooded.

X) Installation and Removal

Installation and the subsequent removal of all mechanical and electrical equipment need to be taken into account during the design of the cover. The following requirements must be carefully catered for:

a) Adequate space for servicing must be provided in the design of the enclosed plant.

b) If the installation and/or removal of the equipment require the service of a crane or any lifting vehicle, then access must be made available within the treatment plant for these lifting vehicles.

c) An adequate number of access covers and sizes of openings for the removal and installation of the equipment shall be provided.

d) The design of an enclosed plant must allow for the plant to be fully operational during the installation and/or removal of any equipment. Alternatively, provisions for temporary bypass should be accommodated to prevent disruption to the sewage flow while this work is being carried out.

e) In situations where it is not possible to readily install a duty and standby unit, the standby unit can be supplied as a separate item which is kept in store, provided that the faulty unit can be removed and the spare unit can be installed within two hours by general maintenance workers using normal tools.

XI) Mechanical and Electrical Requirements

The wiring, lighting and other electrical or mechanical equipment and appliances that have the potential to generate sparks that may trigger an explosion shall be designed and installed to meet the relevant safety codes to avert the possibility of an explosion.

XII) Building Plan Approval

If a building structure is used to house the enclosed treatment plant, then the design of this building must comply with the requirements stipulated by the relevant Building By-Laws.

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7.4 Covered and Buried Treatment Plants

7.4.1 Definition

Covered and buried treatment plants refer to treatment plants with covers that are placed below ground or not more than 1.2 m above ground level. Covers are provided to reduce the odour, noise and visual impact.

This type of plant is only applicable to Class 1 and Class 2 sewage treatment plant with treatment capacity no more than 5000 PE. Special approval by the Commission must be obtained if the plant capacity exceeds 5000 PE. A compromised buffer zone of 10 m minimum from the fence to the nearest building boundary line must be provided for this type of plants. However, the height of the structure is normally limited to 1.2 m above ground.

7.4.2 General

Covered and buried treatment plants have inherent hazard and restriction in operability in their actual operation and maintenance. The requirements in the following sections serve to highlight the minimum improvements that must be made to these plants in addition to those set out in Section 3, 4, 5 and 6 of this Volume.

7.4.3 Specific Requirements for Covered or Buried Plants of 5,000 PE or Less

I) Openings of Covered and Buried Tanks

The design of these tanks must allow for adequate openings so that the operator can carry out routine operation and maintenance works in a safe, efficient and effective manner. These requirements apply to all unit processes that are covered or buried from the inlet works to the effluent chamber. Staggered square openings of roughly 600 mm x 600 mm employed in the past for plants of this nature would not be acceptable. These openings, as a minimum, must be opened top around the periphery of the tank.

II) Access for Routine Operations and Maintenance of the Plant

The designer must take into account the confined space and other related safety issues for entry into such a tank. Provision of proper access into each individual tank is mandatory. Where the depth exceeds 2.5 m, steps with intermediate landings must be included. Other requirements, such as adequate ventilation prior to tank entry, must be considered and provided in the design.



III) Pipework and Aeration System Requirements

Piping for buried plant shall be exposed and accessible for ease of maintenance. PVC pipes are not allowed.

The aeration system (diffuser) must be retrievable from top opening without emptying the tank.

VI) Lighting

Adequate lighting must be provided through adequate opening at the top of these covered or buried tanks to provide a good view of the treatment process such as the air diffusion system, screening, degritting and secondary clarification. This is important for daily plant operations through visual inspection of the individual unit process and routine maintenance of the plant.

V) Hand Railings

Hand railing provisions must be made to prevent falling into open spaces. These hand rails must be provided on the perimeter of the open tanks and further enhanced with kick plates.

VI) Desludging Activities

Adequate access within the proposed treatment plant site is to be made available to allow for desludging tankers to be within the reach of the waste activated sludge storage tanks without undue difficulty of maneuvering the vehicle or damaging the buried tanks or pipe works.

VII) Labeling of Treatment Unit Process

Labeling of each treatment unit is to be provided, from the inlet works to the secondary clarifiers, to avoid confusion with the similar geometry and sizes used for most treatment units.

VIII) Noise Control

Due to the compromised buffer requirements and proximity to adjacent developments, the potential for noise pollution is accentuated. The designer must ensure all noise generating mechanical and electrical equipment within the treatment plant must be contained and treated acoustically to meet compliance to existing noise levels stipulated by the Department of Environment and that set out in Section 4.

IX) Ventilation

Adequate ventilation must be made available to allow for the safe routine operation and scheduled maintenance of the treatment plant. During

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design, this ventilation aspect must be considered. The type of ventilation, portable or permanent, must also be determined during design stage.

X) Odour Control

Odour Control systems to be provided as required in compliance to the EQA.

XI) Buoyancy Effects

The designer must account for the buoyancy effects in the design of buried or covered tanks. This effect is of concern during high groundwater conditions and emptying of the tank content during desludging works. Furthermore, the designer must ensure that the design of these tanks accounts for the hydrostatic force exerted on the floor from the outside does not exceed the compressive strength of these covered or buried tanks. This is to prevent any breakthrough of the floor and subsequent failure of the tank.

The designer must ensure that the design of these tank at worse case scenario where the tank is fully emptied. This is to prevent any breakthrough of the floor and subsequent failure of the tank.

XII) Covers

Covers if employed for odour, visual and noise impacts shall be subjected to the following requirements:a) Lifting may be unaided if the covers are hinged and weigh less

16 kg.b) Assisted lifting is required if the covers weigh equal to or above

16 kg.c) The cover shall comply with BS EN124 loading requirements.d) If the cover is exposed to the environment,

i) Plastic or fibreglass cover if used, must be manufactured with UV inhibitor and will not warp or deform due to weathering effect.

ii) Metal covers if used, must have appropriate corrosion resistant coating in accordance to Section 4 of this Volume.

iii) Where chipping might occurs at the edge of the cover, stainless steel reinforcement frame on all sides of a plastic or FRP cover shall be provided.

XIII) Fencing

Adequate fencing must be provided for all plants. Adequate security shall be provided against unauthorised access.



7.5 Guidelines for Homestead Developments

7.5.1 Single Developments up to 30 Units or 150 PE in Total

Individual septic tanks may be allowed for single developments of up to 30 units or 150 PE in total.

Septic tanks will be regarded as temporary treatment plants.

The owner must provide all septic tanks as part of the owner’s infrastructure works.

Septic tanks must be constructed to standard design in compliable with MSIG Volume 5.

7.5.2 Single Developments Over 30 Units in Total With Average Housing Density Greater Than Five Units per Hectare

For single developments over 30 units in total with an average housing density greater than 25 persons per hectare, a sewer reticulation and a communal treatment plant must be provided.

The treatment plant may be classified as permanent.

Sewer reticulation must be appropriately designed to achieve acceptable hydraulic conditions within topographic and routing parameters.

7.5.3 Single Developments Over 30 Units in Total with Average Housing Density Less Than Five Units per Hectare

For single developments over 30 units in total and with an average housing density of less than 25 persons per hectare, a sewer reticulation and a communal treatment plant is preferred.

The treatment plant may be classified as permanent.

Where the terrain of the development is such that if a communal system is constructed it will require the construction of too many intermediate pump stations, then individual treatment facilities may be considered, subject to the following conditions:

i) The individual system must be a system approved by the Commission.

ii) Where the ground conditions permit, soakaway trenches must be used for disposal of the final effluent from the treatment systems.

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iii) Developers shall ensure that home owners enter into an agreement with the supplier of the systems or licensed contractors, to carry out operation and maintenance of the system as per design requirements.

iv) Tanks shall be desludged by the Service Licensee as per terms of the agreement signed between the Services Licensee and the Commission.

v) The Commission and DOE may impose stringent conditions, if they believe that such measures are required to ensure that the sewage from the development will not result in an adverse impact on the environment.

All septic tanks shall be designed in accordance with the requirements in MSIG Volume 5.

7.6 Non-Compliance with Standards

7.6.1 Introduction

This section describes the types of incidents, which are outside the control of the operator that may cause a sewage treatment plant to fail its effluent consent. Generally, the more sophisticated the treatment process, the more a process is at risk of failure from one of these incidents. It would be unreasonable to expect the operator of the treatment plants to perform within the effluent quality standards following such incidents. However, the operator must always use his best endeavours to rectify the situation as soon as practicable following such an incident.

The following potential incidents are treated as special cases when meeting absolute compliance with Standard A or Standard B.

7.6.2 Types of Incident’s that Can Cause Treatment Plant Failure

I) Power Interruption

An interruption in the power supply to a treatment plant will cause failure in all mechanical treatment processes.

Some large treatment plants have emergency generators which can be brought on stream to ensure inlet pumping continues.

However, the crude sewage will pass through the plant receiving only rudimentary treatment and will probably fail to comply with Standard A and Standard B.

Furthermore, all existing sewage treatment plants have to be restarted manually once they are tripped through power failure.



On new works, all treatment plants will be fitted with auto-restart facilities for immediate resumption of operation when power is reconnected.

II) Lightning

When buildings or cabinets housing electrical control equipment are struck by lightning, fail safe surge protection equipment trips all mechanical equipment.

This requires all the equipment to be reset and switched on again. On an unmanned plant there will be a delay between the trip-out following the lightning strike and the operators getting to the plant to reset the equipment.

During this period the plant may fail to comply with the relevant standards.

III) Storm and Flood

During periods of very heavy rain, areas of the local sewer network may suffer such ingress of storm water that surcharge of the sewer system will result, causing abnormally large flows to arrive at the STP inlet.

Under these conditions, the treatment plant would receive much higher flows than that designed for and would suffer severe hydraulic overloading.

The effect would be a rapid wash through of sewage and solids causing the works to fail to meet standards.

IV) Major Mechanical Breakdown

In many existing sewage treatment plants, particularly the small ones, insufficient standby equipment has been provided by the developer.

All new plants must be equipped with standby units having an automatic change over system in the event of failure.

Existing plants may be out of action for several days while repairs are carried out to failed equipment. To help alleviate this problem, the operator needs to carry critical spare parts to help speed the repair process.

V) Vandalism, Theft and Criminal Damage

If a treatment plant is subject to this form of interference, then the treatment process is at risk until the necessary repairs are carried out.

Reasonable measures must be taken to deter vandalism.

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VI) Deliberate Discharge of Toxic Chemicals

From time to time, irresponsible industrialists may discharge chemical waste to the sewer in contravention of all the relevant legislation.

This may occur as a one-off dumping exercise, or may be the result of a small continuous discharge from a trade process which affects the treatability of the sewage and causes the treatment plant to fail.

VII) Accidental Discharge of Strong Loads or Toxic Substances

From time to time, genuine accidents occur on industrial premises or on the highway that result in abnormal discharges to the sewer. These may take the form of serious fires at industrial premises, the sudden failure of large storage tanks or a major traffic incident involving the transport of liquid products.

Such discharges to the sewer system would almost always result in the sewage treatment plant failing to comply until the effects of the discharge have passed through the system.

VIII) Major Blockages in the Sewer Network System

A blockage in the main sewer network system often causes the sewage to build up behind the blockage and turn septic.

The sudden release of this large volume of septic sewage by the clearance of the blockage, may cause temporary overloading of the treatment plant and lead to a reduction in effluent quality beyond the absolute standard for a short period of time.

IX) Defect

Completed treatment plant to be inspected by competent personal. Visual inspection to be conducted during the final stage of construction. Two type of defect generally detected during inspection :

a) Minor DefectNon-critical, do not immediately or unduly affect the performance of the plant but nevertheless, require attention to rectify faults within reasonable time frame.

b) Major DefectCritical or serious and require immediate action to be taken in rectifying faults, impair plant performance, unit processes, or system components.



Consultant’s responsibility to ensure compliance of the design standard and good engineering practice.

7.7 Energy Saving

In selection of treatment process or equipment, the designer should consider the best product which minimized the power consumption for process and major plant equipment without compromising on the quality of treatment discharge.

7.8 Recycle and Reuse

a) To promote/encourage designer to look into potential of energy reuse.

b) To utilize the recycle water (reclaim water) for cleaning and landscaping purposes,

c) To promote and encourage design to identify potential of sludge reuse and/or recycle.

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Section 8

Package SewageTreatment Plant

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8.1 Definition

A package sewage treatment plant is a form of treatment plant both for fixed film and suspended growth processes. It shall consist of a prefabricated biological treatment system and be limited to the development of the sewage treatment system between the ranges of 150 to 5000 populations equivalent (PE).

The package sewage treatment plant is only applicable to Class 1 and Class 2 STP as defined in Section 4 of this Guidelines. The prefabricated biological treatment system shall have been given approval by the Commission prior to the application.

The major components of a package sewage treatment plant are:

I) Inlet works a) Primary screen.b) Pump Station (if applicable).c) Secondary screen.d) Grit and grease chambers.

II) Biological treatment systema) Balancing Tank.b) Aeration/Anoxic Tank.c) Clarifier.d) Sludge Holding Tank.e) Aeration System including blower house.f) Sludge Dewatering System.

III) Outlet works a) Disinfection that can be physical, chemical or radiation.

Package sewage treatment plants fall under the category of covered/buried treatment plants.

8.2 Land Area Requirement

The land area requirements for package sewage treatment plants shall comply with those recommended for Class 1 and Class 2 Plants in Section 2 of this Guidelines.

The net area does not include the 10 m buffer zone surrounding each plant, but does include the 5 m set backs and access paths within the plant.

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8.3 Design Requirement

a) All calculations regarding the inlet works, outlet works, biological processes and hydraulics shall follow the design criteria as stipulated in the Section 4 and Section 5 of this Guidelines.

b) All units of package sewage treatment plant and foundation shall be designed to meet the extreme case scenario as follows:i) When the tanks are fully emptied;ii) During high groundwater conditions.

c) The structural design of a tank shall consider all factors that can affect the strength and integrity of the tank, like soil conditions, area of installation, etc. All tanks shall be structurally designed to withstand the maximum earth load and hydrostatic pressure equivalent to a backfill depth of 1 m.

d) All civil works of blower house, pump house and control panel room shall be as recommended in Section 4 and 5 of this Guidelines.

e) The minimum design life span of the components of the package sewage treatment plant shall be as Table 8.1 below:

Table 8.1 Minimum Design Life Span of Package Sewage Treatment Plant Components

Component Design Life SpanPrefabricated tank and other structural components > 50 years

Civil > 50 yearsMechanical & Electrical 10 years

8.4 Components of Package Sewage Treatment Plant8.4.1 Layout, Piping and Arrangement of Prefabricated Biological

Treatment System

The prefabricated biological treatment system shall be packaged in terms of layout, piping, arrangement of the tanks and the biological processes.

The dimension of each tank shall be fixed for each model of the prefabricated system. All these items shall not be changed once approved.

8.4.2 Prefabricated Tanks

The physical properties of the tanks for package plants shall meet the material requirements for STP structures as stipulated in Section 4 of this MSIG. The prefabricated tanks shall come as complete tanks, thus no



welding, jointing, fabrication/moulding of tanks’ components is allowed at site. The route for delivery of tanks shall be planned properly, so as not to cause any damage to road facilities and harm to road users.

8.4.3 Process Treatment Units/Components

The following table provides the recommended number of tanks for each unit process against the PE size. The effective volume consideration is also incorporated in the table.

Table 8.2 Recommended Number of Tanks and Effective Volume Consideration for Various Unit Processes



8.4.2 Prefabricated Tanks The physical properties of the tanks for package plants shall meet the material requirements for STP structures as stipulated in Section 4 of this MSIG. The prefabricated tanks shall come as complete tanks, thus no welding, jointing, fabrication/moulding of tanks’ components is allowed at site. The route for delivery of tanks shall be planned properly, so as not to cause any damage to road facilities and harm to road users.

8.4.3 Process Treatment Units/Components The following table provides the recommended number of tanks for each unit process against the P.E size. The effective volume consideration is also incorporated in the table.

Table 8.2: Recommended Number of Tanks and Effective Volume Consideration for Various Unit Processes

Max Number of Tanks

Max Number ofTanks Name of Tank

PE ≤1 000 PE >1 000

Effective Volume

Balancing Tank

1 2

Aeration Tank

2 4

Anoxic Tank 2 4

Clarifier

2 4

Sludge Holding Tank

2 4

Tanks

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Note: Low water level (LWL) is the minimum submergence level of the pumps to protect it from damage. It is dependent on the type of the pumps, thus the low water level shall be set according to the pump’s manufacturers requirement Top Water Level (TWL) is the normal operating water level with adequate freeboard provided.

8.5 Appurtenances

8.5.1 Piping system

8.5.1.1 General

a) The piping used shall be an approved product, supplied and manufactured by a supplier/manufacturer approved by the Commission and shall be suitable for the application.

b) The arrangement of the piping system and interconnection pipes in the tanks shall not obstruct maintenance work of the equipment in the tanks.

c) All the buried piping shall be properly bedded and supported with the selected compacted fill material.

d) All the above ground piping shall have a minimum distance of 75 mm from the ground level.

e) It shall be provided with a proper pipe support and bracket. The bracket shall be made of hot dipped galvanised steel.

f) The arrangement/layout of the above ground piping shall minimise obstruction and maneuverability.

g) Any installation or assemblies of pipe support that is attached to the prefabricated tank is not allowed.

8.5.1.2 Inlet and Outlet Pipes

All inlet and outlet pipes of the units of prefabricated biological treatment system must be pre-fitted at the factory. On-site drilling for holes is strictly prohibited. All jointing and pipe holes connection shall be factory fabricated/moulded.

8.5.1.3 Aeration Pipes

a) The air distribution pipe used shall be rigid and can withstand temperatures up to 150 ºC and pressures of 25% more than the design pressure of the blower.



b) The air pipe from the blower to the process unit shall be above ground.

8.5.1.4 Sludge Transfer Pipes

a) No thread union/coupling is allowed at the sludge transfer pump piping. The connection shall be double flange with Grade 304 stainless steel bolt and nut.

b) No bending is allowed for the sewage distribution pipe. A chamber shall be provided for any changing direction of the flow.

8.5.1.5 Effluent Pipes

The effluent discharge piping system that passes through/bypasses the disinfection treatment facility shall be designed so as not to cause any nuisance.

8.5.2 Pumping System

The pumps installed in the package system shall meet the requirements as stated in Table 8.3 below:

Table 8.3 Technical Requirements of Pumping System

Name of Pump Transfer Pump Sludge Transfer Pump RAS/WAS Pump

Application Area Balancing Tank Sludge Holding Tank Clarifier

Minimum Throughlet 50 mm 50 mm 50 mm

Control Automatic control by float switch

Manual control by timer

Automatic control by timer and solenoid valve

Number of Pump 1 duty, 1 standby 1 duty for each tank 1 duty for each tank

Type of PumpMechanical Submersible Pump

Mechanical Submersible Pump or Self Priming Pump

PE < 1000 : Air lift

PE ≥ 1000 : Mechanical Pump

Necessities Mandatory

Accessories All pumps shall be completely installed with duct foot, guide rail and lifting chain made of Grade 304 stainless steel.

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Note: 1) Non-submersible pumps shall be provided with parking bay with shade.

2) The duct foot shall be installed and assembled at the factory. No installation/assemblies at site are allowed except for the connection of the transfer pipe and the guide rail. All fasteners of the duct foot shall be watertight.

8.5.3 Diffuser

a) All diffusers must be supported from the tank base. A typical drawing of the diffuser support is shown in Figure 8.1.

b) The diffuser shall not be bolted to the bottom of the tank.

c) The diffuser shall be removable and easy to re-install.

8.5.4 Flow Distribution Chamber

a) Distribution box shall be provided with adjustable features. A typical drawing of the distribution box is shown in Figure 8.2.

b) The design and construction of the distribution chamber shall prevent any sedimentation.

8.5.5 Manhole Cover/Inspection Chamber Cover

The manhole cover shall follow the requirements as in Table 8.4:

Table 8.4 Technical Requirements of Manhole Cover

Description FRP HDPE Ductile/Cast Iron

Size 600 mm x 600 mm or 600 mm diameter

Installation At any location on top of the tank except at assembly joints, rib or reinforced ring location.

Load Bearing Capacity ≥ 3.5 kN/m2 (BS EN 12255-1:2002(E))

Maximum Deflection Limit

10 mm or the span divided by 200, whichever is smaller (BS EN 12255-1:2002(E))

Class B 125 in accordance to BS EN 124:1994 or equivalent

Personnel Load 125 kN (fully walk-able) (BS EN 124:1994)

Design Safety Factor 4:1 for allowable stresses shall be met for all load combinations (ANSI/ASCE 7-98)



Table 8.4 Technical Requirements of Manhole Cover (Continued)

Description FRP HDPE Ductile/Cast Iron

Temperature Range 27°C – 35°C (to incorporate thermal expansion and contraction)

Standard colour Black Black Black

Coating Aliphatic acrylic polyurethane non-skid coating NA

- Epoxy coating of 200 µm

- Hot dip galvanised of 200 µm

Resin Corrosion resistant general purpose polyester

NA NA

UV Protection Ultraviolet-light inhibitors shall be added to the laminate

Carbon black NA

Note: 1. The collar of the manhole shall be raised with a minimum height of 100 mm above ground level.

2. The cover shall be equipped with a frame support and hinge, and attached to the manhole opening.

3. Each manhole cover must be properly labeled / marked for ease of identification of the unit process of the system.

4. NA – not applicable

8.5.6 Anchor System Loading

The tank anchor system (straps, cables, turnbuckles, etc.) shall have strength of at least 1.5 times the maximum uplift force of an empty tank without backfill in place. All wire straps, cables and turnbuckles must be made of Grade 304 stainless steel.

8.5.7 Landscaping

The landscaping of the sewage package system shall be in accordance with those recommended in Section 6 of this Guidelines.

8.5.8 Odour Treatment

The odour treatment shall be incorporated into the package sewage treatment plant and shall follow the requirements stipulated in Section 7.4.

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8.5.9 Ancillary Facilities

The requirement and criteria of other ancillaries such as lifting facilities, road, water tank, stand pipe, etc shall be in accordance with the design criteria as stipulated in Section 6 and special requirements in Section 7.4.

8.6 Marking and Labelling

Each tank shall at a minimum be marked with the following information:

• Manufacture’s name or trademark

• Manufacturing serial number

• Manufacturing date (MM/YY)

• Diameter and Capacity

• Citation of the standard

The markings shall be printed and adhered to the tank.

Appendix A

Tables

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Appendix A


Appendix A Tables

Table A1 Contaminants of Concern in Sewage Treatment

Table A2 Typical Composition of Untreated Domestic Sewage

Table A3 Major Biological Treatment Processes Used for Sewage Treatment

Table A4 Interim National River Water Quality Standards for Malaysia

Table A5 River Clarification

Table A6 The Occupational Safety and Health Act 514, 1994 – Brief Summary of Contents

Table A7 Permissible limits for potentially toxic elements in soil

Table A8 Options for disposal of Sludge and reuse of biosolids

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Contaminants Reason for Concern

Suspended solids Suspended solids can lead to the development of sludge deposits and anaerobic conditions when untreated sewage is discharged in the aquatic environment.

Biodegradable organics

Composed principally of proteins, carbohydrates and fats, biodegradable organics are measured most commonly in terms of BOD (biochemical oxygen demand). If discharged untreated to the environment, their biological stabilisation can lead to the depletion of natural oxygen resources and to the development of septic conditions.

Pathogens Communicable diseases can be transmitted by the pathogenic organisms in sewage.

Nutrients Both nitrogen and phosphorus, along with carbon, are essential nutrients for growth. When discharged to the aquatic environment, these nutrients can lead to the growth of undesirable aquatic life. When discharged in excessive amounts on land, they can also lead to the pollution of groundwater.

Refractory organics These organics tend to resist conventional methods of sewage treatment. Typical examples include surfactants, phenols and agricultural pesticides.

Heavy metals Heavy metals are usually added to sewage from commercial and industrial activities and may have to be removed if the sewage is to be reused.

Dissolved inorganic solids

Inorganic constituents such as calcium, sodium and sulphate are added to the original domestic water supply as a result of water use and may have to be removed if the sewage is to be reused.

Table A1 Contaminants of Concern in Sewage Treatment

Appendix A - Tables


Table A2 Typical Composition of Untreated Domestic Sewage

ConstituentConcentration (mg/l)

Strong Medium Weak

Solids, total 1200 720 350

Dissolved, total 850 500 250

Fixed 525 300 145

Volatile 325 200 105

Suspended, total 350 220 100

Fixed 75 55 20

Volatile 275 165 80

Settleable solids, ml/l 20* 10* 5*

Biochemical oxygen demand, 5 day, 20°C (BOD5, 20°C)

400 250 110

Total organic carbon (TOC) 290 160 80

Chemical oxygen demand (COD) 1000 500 250

Nitrogen (total as N) 85 40 20

Organic 35 15 8

Free ammonia 50 25 12

Nitrites 0 0 0

Nitrates 0 0 0

Phosphorus (total as P) 15 8 4

Organic 5 3 1

Inorganic 10 5 3

Chlorides 100 50 30

Alkalinity (as CaCO3) 200 100 50

Grease 150 100 50

* All values except settleable solids are expressed in mg/l.

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218

Table A3 Major Biological Treatment Processes Used for Sewage Treatment

Type Common Name Use

Aerobic processes

Suspended growth

Activated-sludge process

Conventional (plug flow)

Continuous-flow stirred-tank

Step aeration

Pure oxygen

Modified aeration

Contract stabilisation

Extended aeration

Oxidation ditch

Sequencing batch reactor

Suspended-growth nitrification

Aerated lagoons

Aerobic digestion

Conventional air

Pure oxygen

High-rate aerobic algal pond

Carbonaceous BOD removal (nitrification)










Nitrification



Stabilisation, carbonaceous BOD removal


Carbonaceous BOD removal

Attached growth

Trickling filters

Low-rate

High-rate

Roughing filters

Rotating biological contactors

Packed-bed reactors






Combined processes

Trickling filter, activated sludge

Activated sludge, trickling filter



Anoxic processes

Suspended growth

Suspended-growth denitrification Denitrification

Attached growth

Fixed-film denitrification Denitrification

continued

Appendix A - Tables


Table A3 (continued)

Type Common Name Use

Anaerobic processes

Suspended growth

Anaerobic digestion

Standard-rate, single-stage

High-rate, single-stage

Two-stage

Anaerobic contact process






Attached growth

Anaerobic filter

Anaerobic lagoons (ponds)

Carbonaceous BOD removal, stabilisation (denitrification)

Carbonaceous BOD removal (stabilisation)

Aerobic/anoxic or anaerobic process

Suspended growth

Single-stage nitrification-denitrification

Nitrification-denitrification

Carbonaceous BOD removal, nitrification, denitrification

Nitrification, denitrification

Attached growth

Facultative lagoons (ponds) Carbonaceous BOD removal

Combined processes

Maturation or tertiary ponds

Anaerobic-facultative lagoons

Anaerobic-facultative-aerobic lagoons




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Table A4 Interim National River Water Quality Standards for Malaysia

Parameters (units)Classes*

II IIA IIB III IV V

Ammoniacal Nitrogen (mg/l)

0.1 0.3 0.3 0.9 2.7 >2.7

BOD5 (mg/l) 1 3 3 6 12 >12

COD (mg/l) 10 25 25 50 100 >100

DO (mg/l) 7 5-7 5-7 3-5 <3 <1

PH 6.5-8.5 6-9 6-9 5-9 5-9 -

Colour (TCU) 15 150 150 - - -

Elect. Cond.# (mmhos/cm)

1000 1000 - - 6000 -

Floatables N N N - - -

Odour N N N - -

Salinity# (0/00) 0.5 1 - - 2

Taste N N N - -

Total Diss. Solid# (mg/l)

500 1000 - - 4000

Total SS (mg/l) 25 50 50 150 300 >300

Temperature (0C) - Normal ±2

- Normal ±2

- -

Turbidity (NTU) 5 50 50 - - -

F. Colif. †(counts/100 ml)

10 100 400 5000 5000 -

Tot. Colif. (counts/100 ml)

100 5000 5000 (20 000)‡

50 000

(20 000)‡

50 000

> 50 000

N No visible floatable materials/debris, or no objectionable odour, or no objectionable taste

* Classes are described on the following table# Related parameters, only one recommended for use† Geometric mean‡ Maximum not to be exceeded

Appendix A - Tables


Table A5 River Clarification

Class Uses

I Conservation of natural environment♦Water supply I - practically no treatment necessary (except by ♦disinfection or boiling only)Fishery I - very sensitive aquatic species♦

IIA Water supply II - conventional treatment required♦Fishery II - sensitive aquatic species♦

IIB Recreational use with body contact

III Water supply III - extensive treatment required♦Fishery II - common, of economic value, and tolerant species♦Livestock drinking♦

IV Irrigation

V None of the above

Note: This data is adapted from the Water Quality Criteria and Standards for Malaysia, Final Report July 1986, Department of Environment.

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Table A6 The Occupational Safety and Health Act 514, 1994 - Brief Summary of Contents

Part No. Content

I Preliminary

II Appointment of Offices

III National Council for Occupational Safety and Health

IV General Duties of Employers and Self Employed Persons

V General Duties of Designers, Manufacturers and Suppliers

VI General Duties of Employees

VII Safety and Health Organisations

VIII Notification of Accidents, Dangerous Occurrence, Occupational Poisoning and Occupational Diseases and Inquiry

IX Prohibition Against use of Plant or Substance

X Industry Codes of Practice

XI Enforcement and Investigation

XII Liability for Offences

XIII Appeals

XIV Regulations

XV Miscellaneous

The Occupational Safety and Health Act (OSHA) was enacted by the Parliament in 1994. In general, it is an enabling law in that the duties, responsibilities, penalties and guidelines are to be followed by each specific industry. The following table provides an outline of OSHA.

Parts of OSHA have a specific target audience. For example, if the professional is a designer, then Part V would be applicable with respect to Occupational, Safety and Health in their design.

Appendix A - Tables


Table A7 Permissible limits for potentially toxic elements in soil

Parameters Limits (mg/kg)

Zinc 900

Copper 250

Nickel 150

Cadmium 12

Lead 1000

Mercury 4

Chromium 1000

Arsenic 150

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Table A8 Options for disposal of Sludge and reuse of bio-solids

NoType of sludge/

by-productSource/ Treatment

Process

Option for Disposal or Utilization

1 Liquid primary sludge and septage

- Imhoff tanks- Primary and secondary

clarifiers- Septic Tanks

D

2 Dewatered primary sludge and dewatered septage

- Drying beds- Mechanical dewatering

equipment

C, D, I, S

3 Pond sludge - Oxidation ponds- Aerated lagoons- Waste stabilization

ponds

D, F, R

4 Dewatered pond sludge - Drying beds- Mechanical dewatering

C, D, F, I, R, S

5 Digested sludge - Digesters- Sludge lagoons- Anaerobic ponds

D, F, R

6 Dewatered digested sludge - Drying beds- Mechanical dewatering

C, D, F, I, R, S

7 Lime stabilised sludge - Lime stabilisation C, D, F, R, S8 Compost product - Composting A, C, D, F, L, R, S9 Thermally dried sludge

(pellets/granules)- Thermal drying A, C, D, F, L, R,

S, SP10 Incinerator ash - Incineration C, D, S, SP

NOTES:A = Use in agricultureC = Disposal to controlled dumpsitesD = Disposal to dedicated sludge disposal sitesF = Use in forestry/non-food cropsI = IncinerateL = Use for landscaping at public amenity areasS = Disposal to sanitary landfill sitesR = Use in rehabilitation of degraded SP = Recycled into special product, e.g. building material

Appendix B

References

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226



Malaysian Standards

♦ MS 29Specification for aggregates from natural sources for concrete♦ MS 144Specification for cold reduced mild steel wire for reinforcement of concrete♦ MS 145Specification for steel fabric for the reinforcement of concrete♦ MS 146Specification for hot rolled steel bars for reinforcement of concrete♦ MS 416Code of practice for the use of structural steel in building♦ MS 523Specification for concrete including ready mixed concretePart 1 Guide to specifying concretePart 2 Methods for specifying concrete mixesPart 3 Procedures to be used in producing and transporting concretePart 4 Procedures to be used in sampling, testing and assessing compliance of

concrete♦ MS 739Specification for hot-dip galvanised coatings on threaded fasteners♦ MS 740Specification for hot-dip galvanised coatings on iron and steel articles♦ MS 822Specification for sawn-timber foundation piles ♦ MS 1037Specification for sulphate resisting portland cement♦ MS 1195Code of practice for structural use of concretePart 1 Design and constructionPart 2 Special circumstancesPart 3 Design charts for singly reinforced, doubly reinforced beams and

rectangular columns♦ MS 1227Specification for portland pulverised fuel ash cement

♦ MS 1228: 1991

Code of Practice for Design and Installation of Sewerage Systems

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♦ MS 1241Specification for fibreglass water tanks - effective capacity of less than 2000 litres♦ MS 1292Specification for rubber seals – water stops for sealing joints in concrete ♦ MS 1387Specification for ground granulated blast furnace slag for use with portland cement♦ MS 1390Specification for glass-reinforced polyester panels and panel water tanks

British Standards

♦ BS 476Fire tests on building materials and structures♦ BS 1161Specification for aluminium alloy sections for structural purposes♦ BS 1615Specifications for anodic oxidation coatings on aluminium.♦ BS 3396Woven glass fibre fabrics for plastics reinforcement♦ BS 3532Method of specifying unsaturated polyester resin systems♦ BS 3749Specification for E glass fibre woven roving fabrics for the reinforcement of polyester and epoxy resin systems♦ BS 4248Specification for supersulfated cement♦ BS 4848Hot rolled structural steel sectionsPart 2 Specification for hot finished hollow sections♦ BS 4921Specification for sherardized coatings on iron and steel♦ BS 5493Code of practice for protective coating of iron and steel structures against corrosion



♦ BS 7079Preparation of steel substrates before application of paints and related products♦ BS 7123Specification for metal arc welding of steel and concrete reinforcement♦ BS 8118Structural use of aluminiumPart 1 Code of practice for designPart 2 Specification for materials, workmanship and protection

European Standard

♦ EN 10088Stainless SteelPart 1 List of Stainless SteelsPart 3 Technical delivery conditions for semi-finished products, bars, rods, wire,

sections and bright products of corrosion resisting steels for general purposes

♦ EN 10029Specification for tolerances on dimensions, shape and mass for hot rolled steel plates 3 mm thick or above♦ EN ISO 9445Continuously cold-rolled stainless steel narrow strip, wide strip, plate/sheet and cut lengths. Tolerances on dimensions and form♦ EN 754Aluminium and aluminium alloys. Cold drawn rod/bar and tube.Part 1 Technical conditions for inspection and deliveryPart 2 Mechanical propertiesPart 7 Seamless tubes, tolerances on dimensions and formPart 8 Porthole tubes, tolerances on dimensions and form♦ EN 755Aluminium and aluminium alloys. Extruded rod/bar, tube and profiles.Part 1 Technical conditions for inspection and deliveryPart 2 Mechanical propertiesPart 3 Round bars, tolerances on dimensions and formPart 4 Square bars, tolerances on dimensions and formPart 5 Rectangular bars, tolerances on dimensions and formPart 6 Hexagonal bars, tolerances on dimensions and formPart 7 Seamless tubes, tolerances on dimensions and formPart 8 Porthole tubes, tolerances on dimensions and form

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Part 9 Profile, tolerances on dimensions and form

♦ EN 1676

Specifications for aluminium and aluminium alloy. Alloyed ingots for remelting.

♦ EN 12373

Specification for aluminium and aluminium alloys. Anodizing.

Part 1 Method for specifying decorative and protective anodic oxidation coatings on aluminium and its alloys.

♦ EN 10162

Specification for cold rolled steel sections. Technical delivery conditions. Dimensional and cross-sectional tolerances.

♦ EN 13923

Filament-wound FRP pressure vessels. Materials, design, manufacturing and testing.

♦ EN ISO 8503

Preparation of steel substrates before applications of paints and related products. Surface roughness characteristics of blast-cleaned steel substrates.

Part 1 Specifications and definitions for ISO surface profile comparators for the assessment of abrasive blast-cleaned surfaces.

♦ EN 10025

Hot rolled products of structural steels.

Part 1 General technical delivery conditions.Part 3 Technical delivery conditions for normalized/normalized rolled weldable

fine grain structural steels.Part 4 Technical delivery conditions for thermomechanical rolled weldable fine

grain structural steels

♦ EN ISO 2063

Thermal spraying. Metallic and other inorganic coatings. Zinc, aluminium and their alloys.

♦ EN 14020

Reinforcements. Specification for textile glass roving.

Part 1 Designation

Part 2 Methods of test and general requirements

Part 3 Specific requirements

♦ EN 10210

Specification for hot finished structural hollow sections of non-alloy and fine grain steels



Part 2 Tolerances, dimensions and sectional properties.

♦ EN 10296

Welded circular steel tube for mechanical and general engineering purposes. Technical delivery conditions.

Part 1 Non-alloy and alloy steel tubes.Part 2 Stainless steel

♦ EN 10297

Seamless circular steel tubes for mechanical and general engineering purposes. Technical delivery conditions.

Part 1 Non-alloy and alloy steel tubes.

♦ EN 10305

Steel tubes for precision applications. Technical delivery conditions.

Part 1 Seamless cold drawn tubesPart 2 Welded cold drawn tubesPart 3 Welded cold sized tubesPart 4 Seamless cold drawn tubes for hydraulic and pneumatic power

systemsPart 5 Welded and cold sized square and rectangularPart 6 Welded cold drawn tubes for hydraulic and pneumatic power systems

♦ EN 14118

Reinforcements. Specification for textile glass mats. (chopped strand and continuous filament mats).

Part 1 DesignationPart 2 Methods of tests and general requirementsPart 3 Specific requirements

♦ EN 10083

Specification for steels for quenching and tempering

Part 3 Technical delivery conditions for alloy steels

ASTM Standard

♦ ASTM D4097

Standard specification for contact-moulded glass-fibre-reinforced thermo set resin corrosion-resistant tanks.

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♦ ASTM E84

Standard test method for surface burning characteristics of building materials.

♦ ASTM C582

Standard specification for contact-moulded reinforced thermosetting Plastic (RTP) laminates for corrosion-resistant equipment.

AS Standard

♦ AS 3750.2

Paints for steel structures – Ultra high-build paint

♦ AS/NZS 3750.12

Paints for steel structures – Alkyd/micaceous iron oxide

♦ AS/NZS 2312

Guide to the protection of structural steel against atmospheric corrosion by the use of protective coatings.

Other Reference Materials

♦ Buffer Guidelines for the Siting and Zoning of Industries, Department of Environment

♦ Environmental Quality Act 1974

♦ Environmental Quality (Sewage and Industrial Effluents) Regulations, 1979

♦ Occupational Safety and Health Act, 1994 (OSHA)

♦ Water Quality Criteria and Standards for Malaysia, Final Report, July 1986, Department of Environment

♦ Environmental Impact Assessment Guidelines for Municipal Solid Waste, Sewage Treatment and Disposal Projects, Department of Environment.

♦ Factories and Machinery Act 1967 (Revised – 1974)

♦ Uniform Building By-Law (UBBL), 1984

♦ Town and Country Planning Act, 1976

♦ Sewerage Services Act 1993

♦ Water Services Industry Act 2006

♦ Electrical Act



Other Guidelines in This Set

The Malaysian Sewerage Industry Guidelines is comprised of 5 volumes:

♦ Volume 1 Sewerage Policy for New Developments

♦ Volume 2 Sewerage Works Procedures

♦ Volume 3 Sewer Networks and Pump Stations

♦ Volume 5 Septic Tanks

Appendix C

Supervisory Control and DataAcquisition System (SCADA)

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C-1 Introduction: Overview

SCADA is the acronym for Supervisory Control And Data Acquisition, SCADA or Human-Machine Interface (HMI). The system allows distributed input to be continuously monitored without the intervention of an operator and allows supervisor or operator (depending on security level) to remotely control of equipment operating status.

Data acquisition begins at the Programming Logic Controller, PLC level and includes meter readings and equipment statuses that are communicated to the SCADA as required. Data is then compiled and formatted in such a way that a control room operator using the HMI can make appropriate supervisory decisions that may be required to over-ride normal PLC controls. (A SCADA system includes all the pieces, HMI, controllers, I/O devices, networks, software, etc.).

SCADA systems typically implement a distributed database which contains data elements called tag points. A tag point represents a single input or output value monitored or controlled by the system. Tag points can be either “hard” or “soft”. A hard point is representative of an actual input or output connected to the system, while a soft point represents the result of logic and math operations applied to other hard and soft points. The point values are normally stored as value-timestamp combinations; the value and the timestamp when the value was recorded or calculated. A series of value-timestamp combinations is the history of that point.

The SCADA provides a user-friendly front-end to a control system containing programmable logic controller (PLC) that provide automated, pre-programmed control over a process. This enables the SCADA system to gather data automatically and remotely rather than manually and site in-situ.

A SCADA software can be linked to a database (normally SQL-Structured Query Language), to provide instant trending, diagnostic data, scheduled maintenance procedures, logistic information, detailed schematics for a particular sensor or machine, and expert-system troubleshooting guides. Most major PLC manufacturers have offered integrated HMI/SCADA systems, many of them using open and non-proprietary communications protocols (such as MODBUS or Profibus).

In short, interfacing on of SCADA with PLC offers efficient monitoring and control of process in a large installation site and with large number of distributed equipment at a site. SCADA provide alarm notification, historical and on-line trending plots of control parameters for effective process monitoring and control. SCADA system can also be implemented with PPM schedule maintenance notification and reminder.

The SCADA that are installed at the remote sites can be linked to a Master Station via communication system (Radio frequency or WIFI or other on-line communication channels). The data from an equipment is collected via on-line data acquisition or, unless otherwise allowed, on batch mode via data logging devices.

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The SCADA software can also activate alarm messaging to inform the operator station for exceptional event (critical alarm) reporting. Remote Access Server (RAS) features can provide for either via Internet or other dial-up method (fixed line and/or wireless modem).

All the proposed SCADA software shall be scalable and flexible enough to allow the integration of any additional SCADA controller in future expansion. It shall provide with many industrial standard protocols to allow the user to integrate easily.

C-2 Purpose

This document will provide basic technical requirement for implementation of integrated SCADA/HMI in sewerage system.

C-3 General Requirements

The SCADA system shall be scalable process control solutions designed to meet the required automation needs in the sewerage industries. The system shall provide the required level of performance, flexibility, ease of use, and low life-cycle cost of ownership, making use of the following technology that includes:

The SCADA system shall be Window based client/server system and make use of the following technologies: -

• Dynamic data caching, alarming, human machine interface, history collection, and reporting functions;

• Web viewable, providing secure, advanced user interface HMI capabilities based on an open industry standard html file format and Web Browser access;

• Extensive list of communication interfaces;• Secure Internet Browser based on-line documentation and support.

C-4 Architecture

The SCADA architecture shall be flexible and scalable to allow expansion requirements. The basic architecture shall incorporate all but not limited to the followings:

• Standard based workstations;• powerful Windows based server(s);• Windows based clients;• Industry communication standards shall follow IEEE specification;• object-based configuration tools;



• controllers/remote terminal units;• with power surge protection;• Modem: digital or analog;• Network switches or routers;• Uninterrupted Power Supply (UPS);• data logger & storage devices for continuous monitoring of operation in

the event of cessation of communication;

C-5 SCADA Requirement

The SCADA shall utilize all but not limited to the followings available technologies and features:

• HMI Web – A web-based architecture that allows HMI and application data which uses HTML display format to provide casual access of process graphic displays.

• Real-time Database – a true Client/Server architecture where a real-time database on the server provides data to a number of client applications including:

o Operator stations o Microsoft office applications (such as Microsoft Excel or Microsoft

Access)o Internet explorer

• Open Systems – incorporates open technologies and standards including SQL, ODBC, DDE, Visual Basic, and other OLE for process control.

• Infrastructure – in cooperate alarm/event management system; configure reports, history collection and a variety of standard system trends.

• On-line documentation – provides users access to system information and documentation.

• Interfaces – Data acquisition ability from a wide variety of remote terminal units and controllers.

Other powerful supervisory control features include:

• Integrated detail displays, custom graphics, alarms, history, and reports• Standard control functions• Operator security• Redundant Windows XP/server operation• A common interface for SCADA and other control types such as Hybrid

Control• Database and diagnostic integration with process and discrete controllers• Graphical building tools• Standard and user-definable application templates• International system and local language support

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• Optional applications such as Alarm Pager interface, Downtime Analysis, and statistical Process Quality Control

Standard facilities shall include but not limited to the followings:• Windows based HMI

Multiple local and remote operator stations Interface: TCP/IP, fieldbus, Modbus, Hart

• Support for redundant controller/RTU communications

Integration of multiple systems Real-time data access for a wide variety of process connected devices

• Supervisory data acquisition and control of controllers and remote terminal units

• alarm management• Extensive historian and trending• Flexible standard or customized reports• Optional Live Video Capture integration• Industry standard local and wide area network integration• Secure data integration with third party applications• ActiveX Document and Scripting support

C-6 Operator Interface

The operator interface station shall allow object based graphics to provide the HMI for the user with object concern. The system shall employ industry de-factor standards, such as Microsoft Windows, HTML and the Internet so as to minimize operator training due to familiarity of operating environment.

Critical information is conveyed using dedicated enunciators for alarms, controller communication failures, operator/controller messages and equipment downtime conditions. A dedicated alarm line shows the most recent (or oldest) highest priority, unacknowledged alarm at all times.

Software system displays shall include but not limited to the followings: -• Menu/navigation displays• Alarm summary• Event summary• Trends• Operating groups• System status displays• Configuration displays• Loop Tuning displays• Diagnostic and maintenance displays• Summary displays



Optional Live Video integration shall provide remote viewing and viewing control features.

Security software feature shall provide restricted access, no access and full access (plant management).

Network access shall permit authorized operator stations on a network to share a preconfigured number of connections to the system. This allows a number of users on a network to access production data on off-line basis.

C-7 Database

The SCADA software shall but not limited to the following real-time database:• Analog configuration parameters• Digital configuration parameters• Accumulator configuration parameters• User defined configuration parameters

Each point in the database has a number of associated configurable parameters, all of which can be referenced relative to a single ‘tag name’.

SCADA shall maintain the real time database that requires frequent high-speed access as memory resident information and other less frequently accessed data as disk resident data. Memory resident data is logged to data storage device every specified time frame defined by the administrator to minimize the loss of data in the event of loss of power.

C-8 Alarm/Event Management

The SCADA software System shall provide comprehensive alarm and event detection, management, and reporting facilities. Alarm presentation of alarm / event management shall include but not limited to the followings:

• Multiple alarm priorities• Dedicated alarm zone• Configurable alarm priority colors• Associated display• Audible alarms• Alarm cutout• Area assignment• Operator log

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• Hierarchical alarming• Alarm/event reporting• Alarm/communication/message/downtime annunciator• Alarm priority escalation

The standard Alarm Summary display shall allow operators to focus on the problem at hand by supporting filters. Alarms may be filtered by:

• Area or location or unit processes• Acknowledge Status• Priority

Colors for the various priority levels of alarms can be configured by the user for display purposes in the Alarm Summary and on custom graphics. The recommended color codes are provided in Appendix 1. The software shall support configuration of alarm priority colors and display on all process graphic displays to enables operators immediately determine critically of the alarm.

The alarm shall annunciate in the status zone blinks with the color of the highest priority for unacknowledged alarm. The alarms configuration shall consist but not limited to the followings:

• SPVHi• SPVLo• TransmitterHi• Transmitter Lo• Trip• Time out

With each of the configured alarms assigns a priority ranging from "Attention" - acknowledge of non-critical alarm that required maintenance attention, "Responsive" - action required with predefined period, "Urgent" - action required immediately.

The Alarm/Event summary shall list but not limited to the followings:• Alarms• Alarm Acknowledgments• Return to normal• Operator Control Actions• Operator Login & Security Level Changes• On-line Database Modifications• Communications Alarms• System Restart Messages



C-9 Historian

Historical trend shall provide wide range of sampling frequencies in both data-point and average formats. The history trend intervals are shall be able to but not limited to the following displays:

• second data-point of pre-defined scale• minute data-point of pre-defined scale• hour data-point of pre-defined scale• minute-average of pre-defined scale• hour-average of pre-defined scale• day-average of pre-defined scale• Month-average of pre-defined scale

The historical data is to be display in various formats describe herewith:• Graphical trend plot displays (average, max, min, and other statically

format)• Tabulation displays (average,max,min, and other statically format)• Query databases of selected parameters.

C-10 Graphical Trending

Graphical trending configuration shall be able to configure by selecting the parameters to be plot and its time-scales. Minimum trend types shall include but not limited to the followings:

• Single andMulti bar graphs (selectable scales)• Single andMulti-line trends plot (selectable scales)• Multi-range trends plot (selectable scales)• X-Y line and scatter trend plots (selectable scales)• Mathematical plots (logarithm scale,moving average, etc)

Functions provided for analyzing and manipulating data include:• Combination real-time/historical plots• zooming, panning, and scrolling• Configurable trend density• Saving of trend plot and expert to various format (*.xls, HTML, XLM,

etc)• clipboard copy/paste enable

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C-11 Report Format

The software shall provide but not limited to the following report formats:

• Alarm/Event Log reports - selectable time frame, filterable events andalarms to enable traceability of alarm.

• ExportableExcel/Accessformat-abletosaveselecteddata/reportformatto Microsoft Excel/Access format.

• Statisticaldataanalysis format -generates reportsof selectable statisticalfunctions such as Max/Min and standard deviation.

• Point Attribute Log - displaying specific attributes selectable from alist.

Reports should be generated as required time frame (interval), event-driven, or on-demand basis. Report may be directed to screen, printer, file, or directly to another computer for analysis or viewing electronically.

C-12 Security

The SCADA software shall provide configurable security levels, control levels and area assignments. These may be configured for each individual operator or alternatively for each operator station. The security levels shall be able to configure the following security levels:

Level 1: Sign-on for View mode onlyLevel 2: View only mode with alarm acknowledgeLevel 3: Level 2 plus control of field parametersLevel 4: Level 3 plus field parameters of level 4, configure standard system

infrastructure such as reportsLevel 5: Level 4 plus user configured field parametersLevel 6: Unlimited access

Operator sign-on/sign-off shall be logged. Any actions initiated by an operator are logged in the Event database with the operator identifier. In addition any control actions to a given point is only allowed if the control level configured in the operator profile exceeds the level assigned to the point.

Logon password shall not be less than 6 alphanumeric characters and shall be encrypted. Operators may change own passwords; however, new password shall not be the same as the last 10 passwords used in the previous 3 months. Three unsuccessful attempts of logon shall lock the operator out for a lock-out period. Once logged on, an operator can log off at any time or will be automatically signed off after a defined period of inactivity.



Area assignments limit operator access to graphics, alarms and point data to assigned areas, providing effective plant partitioning. Individual operator profiles, including security levels, control levels and area assignments, are activated when operators sign on to the system. In addition, area profiles can be created enabling plant areas to be enabled or disabled for control, between certain time and date criteria.

C-13 Scripting

The software shall have the VB or VBA scripting language enable to allow user to create script that will run when a display is active or scripts can also be attached to server objects like point parameters, alarm events, report completion and other events.

C-14 Interfaces

SCADA software provides Data Acquisition and Control facilities to communicate with a wide range of controllers and Remote Terminal Units (RTUs). The controllers connection type shall comply with the following communication protocol:

Serial / TCP/IP / ControlNet / Modbus+ / ASCII / TCP/IP / Ethernet

Data Acquisition –supports acquisition of data using either:Periodic Scanning

C-15 Distributed Server Architecture

Distributed Server Architecture is integrated processes when there are multiple control stations, or for segmenting control across units, providing the ultimate flexibility for both operations and control. Distributed Server Architecture also provides the maximum flexibility for geographically distributed sites.

C-16 Web Server

SCADA software shall provide Web Server capability to provide integration mechanism for plant-centric operational information. Based on the SCADA software Distributed Server Architecture, a web server bridges the Process Control and Enterprise domains, dynamically tracking the “pulse” of the enterprise. Web server brings many benefits to the end user:

• Isolation of non-critical enterprise functions from the process controlsystem

• Consolidatedbusiness system integration to/frommanySCADAsoftwaresystems

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• Consolidation of casual users’ accounts and licenses in one location• Cross-system reporting• Minimal engineering requirements

C-17 Digital Video Monitoring

The software may have optional Digital Video Monitoring that integrates digital video controls and storage with the software to assist in process monitoring. Some of the features are:

• Remotemonitoring of unmanned sites• Integration with SCADA software, providing event-based capture and

storage of video images• Event-activated, user-activated, and scheduled recording• Ability to search stored video, based on SCADA software events• Scalability from 4 cameras tomore than 1,000 cameras.

The DVM shall base on open system hardware that digitizes video from standard video cameras and transports the video to SCADA software clients anywhere on the network for real-time viewing.

C-18 Integrated Maintenance Management

Integrated Maintenance Management (IMM) delivers computerized maintenance management system (CMMS) – completely integrated with SCADA software. IMM shall deliver but not limited to the following key benefits:

• More efficient preventive and predictivemaintenance• Reduced downtime of critical plant equipment• Effectivework scheduling• AutomatedcreationofworkordersfromSCADAsoftwareeventsanddata

values

IMM enables the automated creation, assignment, tracking and closing of maintenance work orders. If required, work orders can also be manually raised. This is all managed from either your IMM SQL server database with full access available through the open Web-based interface of IMM.



C-19 Application Report

The SCADA software shall have the capability to produce but not limited to the following reports:

• BatchReport• Downtime analysis• Schedulemaintenance• Statistical Process&Quality Control (SPQC)• Event archiving• Alarmmessaging (SMS or pager)

Batch Reporting –integrated reporting of batches process data, to be compiled and archived by the SCADA software. The batch reports either as a CSV file or Microsoft Excel, if available.

Downtime Analysis –to detect, record and code any equipment breakdowns or process delays to provide plant downtime analysis. A list of all current downtime events is maintained as well as the history of previous downtime events, with each assigned a category and a reason code. Downtime reports may be printed periodically or on-demand, showing downtime duration sorted by categories and reasons.

Schedule Maintenance –allows supervisory control to schedule at a specified time. The maintenance report of the equipment is to be reported.

Statistical Process & Quality Control (SPQC) - generates statistical report of average (of specified time period) of the real-time data collected by the system.

Event Archiving –archiving events logged data by the system that based on sampling frequency and storage capacity.

Alarm Messaging – reports the alarm messages sent designated supervisors. The report shall incorporate summary of alarm messages by alarm type and supervisors.

C-20 Application Programming Interface

Application programming interface (API) shall be provided for interfacing with SCADA software server and the client network based.

The API (programmed in C/C++(visual) or programmed in VB (Visual Basic)) on the server includes the following functions:

• read andwrite to controlmodule parameters in the database• access to historical data

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• initiate supervisory control actions• access to the alarm/event subsystem• access to user-defined database• provide a prompt for operator input• create alarms/events

C-21 User Documentation

SCADA software documentation shall be made available in three basic forms:• ElectronicOn-lineDocumentation usingHTML Internet Browser• On-lineHelp (F1 function key fromwithin applications)• Printed documentation

C-22 Specifications and Sizing

SCADA software Client/Server Specifications

Basic Server Workstation Specifications

ProcessorMemoryHard Disk SizeDisplay ResolutionOperating System (Minimum)Network Protocols

Pentium Processor (Latest version)1 GB 200 GB1024 x 768, 65K colorsMicrosoft Windows (Latest edition)TCP/IP

Basic Client Workstation Specifications

ProcessorMemoryHard Disk SizeDisplay ResolutionOperating System (Minimum)Network Protocols

Pentium Processor (Latest version)1 GB 200 GB1024 x 768, 65K colorsMicrosoft Windows NT (Latest edition)TCP/IP, NFS



SCADA software Server Performance

Operational Display Update

Maximum Continuous Display Update Rate 1 sec

Typical Field Change to Display Update Time with 100 Parameters Per Display on a Single Station/Server

< 2 sec

Typical Display Call Up Time with 100 Parameters on a Single Station/Server (call up time is dependent ondisplaycomplexity;thisexcludesthefirstinitialcall up)

< 2 sec

SCADA Storage Sizing

Standard Sampling

Rate

DefaultDuration

Default Samples

MaximumDuration

Storage Capacity(maximum no. of

samples)

1 minutes 24 hours 1441 69 days 100 000

6 minute average

7 days 1682 416 days 100 000

1 hour average

7 days 170 11.4 years 100 000

8 hour average

3 months 281 91.2 years 100 000

24 hour average

1 year 368 273.8 years 100 000

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Attachment C - 1: Color Coding for Equipment Status

Status/Alarm Event State

Color & Blinking Status Notes of Event

Running Green (Non-Blinking) Equipment is in operating status

Standby Red (Non-Blinking) Equipment is in standby operating status

Off Red (Blinking) Equipment is “Off” or “Manual” mode.

Trip Amber (Blinking):

Equipment “Tripped” due to the followings reasons:1) ELR detection;2) PSR detection;3) Over-current;4) Over-heated motor;5) MCB Trip;

SP High Level Yellow (Non-Blinking) Alarm event of high level than set point

SP Low Level Light Blue (Non-Blinking)

Alarm event of lower level than set point

Transmitter Hi Yellow (Blinking) Alarm event due to transmitter high (<=4mA) value.

Transmitter Lo Light Blue (Blinking) Alarm event due to transmitter low (<=4mA) value.

Time Out Amber (Blinking) Alarm due to time out by PLC timer or other timer.



Attachment C - 2: SCADA Control and Monitoring Function Requirement

Item

Description of Monitoring Point

(For Each Equipment)

Description of Control

Point(For Each

Equipment)

Analog (A)/Digital (D) SCADA Control /

Monitoring

Qty AI

AO DI

DO

Instrumentation Panel

Instrumentation Panel - Local Indicator 1 1 Instrumentation Panel - Remote Indicator 1 1

Instrumentation Panel - Battery Low Indicator 1 1

TNB Power (kWh meter) Data Record 1 1 PLC System PLC (battery Low) Measure 1 1 Alarm Low (Fault Report) Battery Charger Indicator 1 1 Alarm (Fault Report) Penstock Penstock Panel: Manual Switch Indicator 1 1 Penstock Panel: Auto Switch Indicator 1 1

Penstock Position Actuator (%) IP open close control 1 RTU via RS-485 Serial Link

Alarm - High torque

Penstock - Fully Open Indicator 1 1 Penstock - Fully Close Indicator 1 1

Penstock - To Open / To Close Remote Control 1 1

Penstock - UPS Low Indicator 1 1 UPS (battery Low) Inlet

Penstock Measure 1 1 Primary Coarse Screen Screen - Run Indicator 1 1 Counter - Number of start / stop Screen - Trip Indicator 1 1 Alarm (Fault Report) Screen - Auto Mode Indicator 1 1 Screen - Manual Mode Indicator 1 1

Screen - To Start / Stop Remote Control 1 1

Screen - Run-hour record Reset of Hour-Run meter 0 Software counter running hours

Differential Level : Upstream Indicator 1 1 Control Start / Stop operation by diff. level

Differential Level : Downstream Indicator 1 1 Ref level for upstream.

RSP Pumps Pump - Run Indicator 1 1 Record number of Start / stop Pump - Trip Indicator 1 1 Alarm (Fault Report) Pump - Off (MCCB) Indicator 1 1 Record non-operation hours

Pump - To Start / Stop Remote Start/ Stop 1 1 Software control / PLC

Pump - Run-hour record Reset of Hour-Run meter 0 Software counter running hours

Pump - Ampere Reading 1 1 Record when operation Pump - Voltage Reading 1 1 Record when operation

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Item



Description of Control Point


Analog (A)/Digital (D)

Qty AI

AO DI

DO SCADA Control /

Monitoring

Pump - Soft Starter Amp/Volt Comm.

Parameters Setting / Review 1 1 RJ45 / RS485

Float level US Level Level

measurement 1 1

Float Level - L0 On/Off Indicator 1 1 Cut-off operation Float Level - L1 On/Off Indicator

1 1 Control Start / Stop operation by diff. level

Float Level - L2 On/Off Indicator1 1 Control Start / Stop operation

by diff. level Float Level - L3 On/Off Indicator 1 1 Control Start / Stop operation

by diff. level Float Level - L4 On/Off Indicator 1 1 Control Start / Stop operation

by diff. level Float Level - L0 Fault Indicator 1 1 Forfaultidentification(Alarm

Fault report) Float Level - L1 Fault Indicator

1 1 Forfaultidentification(AlarmFault report)

Float Level - L2 Fault Indicator 1 1 Forfaultidentification(AlarmFault report)

Float Level - L3 Fault Indicator1 1 Forfaultidentification(Alarm

Fault report) Float Level - L4 Fault Indicator 1 1 Forfaultidentification(Alarm

Fault report) Sump Pump / Dewatering

Pump

Pump - Run Indicator 1 1 Record number of Start / stop Pump - Trip Indicator 1 1 Alarm (Fault Report) Pump - Off (MCCB) Indicator 1 1 Record non-operation hours Pump - To Start / Stop Remote Start /

Stop 1 1 Software control / PLC Pump - Run-hour record Reset of Hour-Run

meter 0 Software counter running hours Ampere / Volmeters Pump - Ampere Reading 1 1 Record when operation Pump - Voltage Reading 1 1 Record when operation Float level Float Level - L0: ON / OFF Indicator 1 1 Cut-off operation

Float Level - L1: ON / OFF Indicator 1 1 Control Start / Stop operation by diff. level

Float Level - L0 Fault Indicator 1 1 Forfaultidentification Float Level - L1 Fault Indicator 1 1 Forfaultidentification Secondary Fine Screen Screen - Run Indicator 1 1 Record number of Start / stop Screen - Trip Indicator 1 1 Alarm (Fault Report) Screen - Auto Mode Indicator 1 1 Screen - Manual Mode Indicator 1 1 Screen - To Start / Stop Remote Control 1 1



Item






Qty AI

AO DI

DO SCADA Control /

Monitoring

Screen - Run-hour record Reset of Hour-Run meter 0 Software counter running hours

Mechanical Differential Level : Upstream Indicator 1 1 Control Start / Stop operation

by diff. level

Mechanical Differential Level : Downstream Indicator 1 1 Ref level for upstream.

Screenings Conveyor Screen c/v - Run Indicator 1 1 Record number of Start / stop Screen c/v - Trip Indicator 1 1 Alarm (Fault Report) Screen c/v - Auto Mode Indicator 1 1 Screen c/v - Manual Mode Indicator 1 1 Screen c/v - To Start / Stop Remote Control 1 1

Screen c/v - Run-hour record Reset of Hour-Run meter 0

Software counter / Interlock with screen operation with delay off.

Screenings Wash Water Pumps Wash-water Pump - Run Indicator 1 1 Record number of Start / stop Wash-water Pump - Trip Indicator 1 1 Alarm (Fault Report) Wash-water Pump - Auto Mode Indicator 1 1

Wash-water Pump - Manual Mode Indicator 1 1

Wash-water Pump - To Start / Stop Remote Control 1 1

Wash-water Pump - Run-hour record

Reset of Hour-Run meter 0


Grit / Grease System Grit Blower - Run Indicator 1 1 Record number of Start / stop Grit Blower - Trip Indicator 1 1 Alarm (Fault Report) Grit Blower - Auto Mode Indicator 1 1 Grit Blower - Manual Mode Indicator 1 1 Grit Blower - To Start / Stop Remote Control 1 1

Grit Blower - Run-hour record Reset of Hour-Run meter 0

Software counter / software Timer control operation by rotation.

Grit Pump : On Indicator 1 1 Record number of Start / stop Grit Pump : Trip Indicator 1 1 Alarm (Fault Report) Grit Pump - To Start / Stop Remote Control 1 1

Grit Pump - Run-hour record Reset of Hour-Run meter 0


GritClassifier:On Indicator 1 1 Record number of Start / stop GritClassifier:Trip Indicator 1 1 Alarm (Fault Report) GritClassifier-ToStart/Stop Remote Control 1 1

GritClassifier-Run-hourrecord Reset of Hour-Run meter 0


Grit Auger : On Indicator 1 1 Record number of Start / stop Grit Auger : Trip Indicator 1 1 Alarm (Fault Report)

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Item






Qty AI

AO DI

DO SCADA Control /

Monitoring

Grit Auger - To Start / Stop Remote Control 1 1

Grit Auger - Run-hour record Reset of Hour-Run meter 0


Grit Drum Screen : On Indicator 1 1 Record number of Start / stop Grit Drum Screen : Trip Indicator 1 1 Alarm (Fault Report)

Grit Drum Screen - To Start / Stop Remote Control 1 1

Grit Drum Screen - Run-hour record



Auxiliary LV System

Main LV Board Main Breaker : ON Indicator 1 1 Status

Main LV Board Main Breaker : TRIP (Earth Fault) Indicator 1 1 Alarm (Fault Report)

Main LV Board Main Breaker : TRIP (Over Current) Indicator 1 1 Alarm (Fault Report)

Main LV Board Main Breaker : Ampere Reading 1 1 Record

Main LV Board Main Breaker : Voltage Reading 1 1 Record

Room Temperature Monitoring / Alarm Reading 1 1

Bus Couple : ON Indicator 1 1 Bus Couple : OFF Indicator 1 1 kWHr Meter: Reading 1 1 Record HT System HT Income Panel VCB : ON Indicator 1 1 Status

HT Income Panel VCB: TRIP (Earth Fault) Indicator 1 1 Alarm (Fault Report)

HT Income Panel VCB: TRIP (Over Current) Indicator 1 1 Alarm (Fault Report)

HT Income Panel VCB: Ampere Reading 1 1 Record HT Income Panel VCB: Voltage Reading 1 1 Record Battery Charger Indicator 1 1 Record (Alarm fault) Battery Low Indicator 1 1 Record (Alarm Low)

Room Temperature Monitoring / Alarm Reading 1 1 Record / Alarm (High)

kWHr Meter Reading 1 1 Record Transformer System Transformer Temperature Alarm Indicator 1 1 Record / Alarm (High) Transformer Pressure Alarm Indicator 1 1 Record / Alarm (High) CO2 System

TNB Room: CO2 Panel Activated Indicator 1 1 Record / Alarm (activated)

Switch Gear: CO2 Panel Activated Indicator 1 1 Record / Alarm (activated)

Transformer Room: CO2 Panel Activated Indicator 1 1 Record / Alarm (activated)



Item






Qty AI

AO DI

DO SCADA Control /

Monitoring

Main Switch Room: CO2 Panel Activated

Indicator 1 1 Record / Alarm (activated)

MCC Room: CO2 Panel Activated

Indicator 1 1 Record / Alarm (activated)

Gen Set- CO2 Panel Activated Indicator 1 1 Record / Alarm (activated) CO2 Panel DC supply Battery

LowIndicator 1 1 Record / Alarm (activated)

Gen Set System Gen Set - Run Indicator 1 1 Record number of Start / stop Gen Set - Trip Indicator 1 1 Alarm (Fault Report) Gen Set - To Start / Stop

(Remote)Remote Start / Stop 1 1 Software control / PLC

Gen Set - To Stop (Remote) Remote Start / Stop 1 1 Software control / PLC

Gen Set - Run-hour record Reset of Hour-Run meter 1 Software counter running hours

Gen Set -Battery Charge Indicator 1 1 Record / Alarm (Fault) Gen Set -DC Battery Low Indicator 1 1 Record / Alarm (Low) Gen Set -Diesel Fuel oil low Indicator 1 1 Record / Alarm (Low) Surge Vessel Compressors

System

Air Compressor - Run Indicator 1 1 Record number of Start / stop Air Compressor - Trip Indicator 1 1 Alarm (Fault Report) Air Compressor - Auto Mode Indicator 1 1 Air Compressor - Manual Mode Indicator 1 1 Air Compressor - To Start / Stop Remote Control 1 1

Air Compressor - Run-hour record

Reset of Hour-Run meter 0 Software counter running hours

Surge Vessel Level Indicator Level Measure 1 1 Surge Vessel Pressure Indicator Pressure Measure 1 1 Force Ventilation: Grit System Fan : Manual Indicator 1 1 Fan : Auto Indicator 1 1 Fan : ON / OFF Indicator 1 1 Status & Software counter

running hours Fan : Trip Indicator 1 1 Alarm (Fault Report) Fan : To Start / Stop Remote Start /

Stop 1 1 Gas Scrubber System Scrubber Fan : Manual Indicator 1 1 Scrubber Fan : Auto Indicator 1 1 Scrubber Fan : ON / OFF Indicator 1 1 Status & Software counter

running hours Scrubber Fan : Trip Indicator 1 1 Alarm (Fault Report) Scrubber Fan : To Start / Stop Remote Start /

Stop 1 1 Aeration Blower Blower - Run Indicator 1 1 Record number of Start / stop Blower - Trip Indicator 1 1 Alarm (Fault Report) Blower - Off (MCCB) Indicator 1 1 Record non-operation hours

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Item






Qty AI

AO DI

DO SCADA Control /

Monitoring

Blower - To Start / Stop Remote Start / Stop 1 1 Software control / PLC

Blower - VSD Parameters Speed Control 1 1 RTU via RS-485 Serial Link Blower - Run-hour record Reset of Hour-Run

meter 0 Software counter / software Timer control operation by rotation.

Blower - Ampere Measure 1 1 Record when operation Blower - Voltage Measure 1 1 Record when operation Temperature Sensor Blower - Temperature Measure 1 1 Record & Alarm (High Temp) Air Flow Meter Air Flow Meter Measure 1 1 Record & Alarm (low level) Force Ventilation: Blower

Room

Fan : Manual Indicator 1 1 Fan : Auto Indicator 1 1 Fan : ON / OFF Indicator 1 1 Status & counter no. of start /

stop Fan : Trip Indicator 1 1 Alarm (Fault Report) Fan : To Start / Stop Remote Start /

Stop 1 1

Fan : Run-Hour record Reset of Hour-Run meter 1


D.O. Meter D.O. Meter Measure 1 1 Record / Control Speed &

Alarm (Low) Anoxic Mixer Anoxic Mixer - Run Indicator 1 1 Status & counter no. of start /

stop Anoxic Mixer - Trip Indicator 1 1 Alarm (Fault Report) Anoxic Mixer - Off (MCCB) Indicator 1 1 Record non-operation hours Anoxic Mixer - To Start / Stop Remote Start /

Stop 1 1 Software control / PLC

Anoxic Mixer - Run-hour record Reset of Hour-Run meter 0 Software counter

Anoxic Mixer - Ampere Measure 1 1 Record when operation Anoxic Mixer - Voltage Measure 1 1 Record when operation Primary or Secondary Clarifier Clarifier-Run Indicator 1 1 Status & counter no. of start /

stop Clarifier-Trip Indicator 1 1 Alarm (Fault Report) Clarifier-Off(MCCB) Indicator 1 1 Record non-operation hours Clarifier-ToStart/Stop Remote Start /

Stop 1 1 Software control / PLC

Clarifier-Run-hourrecord Reset of Hour-Run meter 0 Software counter

Clarifier-Ampere Measure 1 1 Record when operation Clarifier-Voltage Measure 1 1 Record when operation



Item






Qty AI

AO DI

DO SCADA Control /

Monitoring

Pump - Run Indicator 1 1 Status & counter no. of start / stop

Pump - Trip Indicator 1 1 Alarm (Fault Report) Pump - Off (MCCB) Indicator 1 1 Record non-operation hours

Pump - To Start / Stop Remote Start / Stop 1 1 Software control / PLC

Pump - Run-hour record Reset of Hour-Run meter 0 Software counter

Pump - Ampere Measure 1 1 Record when operation Pump - Volt Measure 1 1 Record when operation Sludge Flow Meter RAS/WAS Flow Rate Meter Measure 1 1 Record RAS/WAS Flow Rate Totalizer Measure 1 1 Record Flow Meter System

Flow Meter (Datarecordofflowrate) Measure 1 1 Record

Flow Meter (Totalizer) Measure / Reset 1 1 SCADA Software Accumulator Gravity Thickener

G. Thickener - Run Indicator 1 1 Status & counter no. of start / stop

G. Thickener - Trip Indicator 1 1 Alarm (Fault Report) G. Thickener - Off (MCCB) Indicator 1 1 Record non-operation hours

G. Thickener - To Start / Stop Remote Start / Stop 1 1 Software control / PLC

G. Thickener - Run-hour record Reset of Hour-Run meter 0 Software record of running

hours G. Thickener - Ampere Measure 1 1 Record when operation G. Thickener - Voltage Measure 1 1 Record when operation

Thickened Sludge Digester Feed Pump: Primary & Secondary

Feed Pump - Run Indicator 1 1 Status & counter no. of start / stop

Feed Pump - Trip Indicator 1 1 Alarm (Fault Report) Feed Pump - Off (MCCB) Indicator 1 1 Record non-operation hours

Feed Pump - To Start / Stop Remote Start / Stop 1 1 Software control / PLC

Feed Pump - Run-hour record Reset of Hour-Run meter 0 Software record of running

hours Feed Pump - Ampere Measure 1 1 Record when operation Feed Pump - Voltage Measure 1 1 Record when operation

Feed Pump - VSD Parameters Speed Control 1 1 Speed control : RTU via RS-485 Serial Link

Sludge Flow Meter Sludge Feed Flow Rate Meter Measure 1 1 Record Sludge Feed Flow Rate Totalizer Measure 1 1 Record Gas Blower

Gas Blower - Run Indicator 1 1 Status & counter no. of start / stop

Gas Blower - Trip Indicator 1 1 Alarm (Fault Report) Gas Blower - Off (MCCB) Indicator 1 1 Record non-operation hours

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Item






Qty AI

AO DI

DO SCADA Control /

Monitoring

Gas Blower - VSD Parameters Remote Start / Stop 1 1 Speed control : RTU via RS-485

Serial Link

Gas Blower - Run-hour record Reset of Hour-Run meter 0 Software record of running

hours Gas Blower - Ampere Measure 1 1 Record when operation Gas Blower - Voltage Measure 1 1 Record when operation Temperature Sensor Gas Blower - Temperature Measure 1 1 Record & Alarm (High) Gas Flow Meter Gas Flow Meter Measure 1 1 Record Digester Gas Detector Meters

H2S Meter at Dewatering House Measure 1 1 Record & Alarm (Detection & Fault)

Methane Gas Meter Measure 1 1 Record & Alarm (Detection & Fault)

PVRV Sensor Meter Measure 1 1 Record & Alarm (High-Low & Fault)

Internal Digester Gas Analyzer Measure 1 1 Record & Report Floating Roof Gas Holder

Floating Roof Level Measure 1 1 Record & Alarm (High-Low & Fault)

High Lever Alarm Indicator 1 1 Alarm (High) Low Lever Alarm Indicator 1 1 Alarm (Low)

PVRV Sensor Meter Measure Record & Alarm (High-Low & Fault)

Gas Flare System

Gas Control Actuator Valve: Full Open Indicator 1 1 Record & Timer

Gas Control Actuator Valve: Full Close Indicator 1 1 Record & Timer

Gas Control Actuator Valve: Manual Indicator 1 1

Gas Control Actuator Valve: Auto Indicator 1 1 Program Control operation

Gas Control Actuator Valve: ON Indicator 1 1 Status & counter no. of start / stop

Gas Control Actuator Valve: TRIP Indicator 1 1 Alarm (Fault Report)

Gas Control Actuator Valve: To Turn Clockwise

Remote Start / Stop 1 1 Software control / PLC

Gas Control Actuator Valve: To Turn Counter-Clockwise


Pilot Light Igniter Indicator 1 1 Record&Alarm(flame

distinguished) Flare Igniter : Manual Indicator 1 1 Flare Igniter : Auto Indicator 1 1 Program Control operation Flare Igniter : ON Indicator 1 1 Program Control operation

Flare Indicator Indicator 1 1 Record&Alarm(flamedistinguished)

Pressure Indicator: Inlet Measure 1 1 Record & Report Fault Pressure Indicator: Discharge Measure 1 1 Record & Report Fault Sludge Feed Pump to Belt Press Belt Press Feed Pump - Manual Indicator 1 1



Item






Qty AI

AO DI

DO SCADA Control /

Monitoring

Belt Press Feed Pump - Auto Indicator 1 1 Program Control operation

Belt Press Feed Pump - Run Indicator 1 1 Status & counter no. of start / stop

Belt Press Feed Pump - Trip Indicator 1 1 Alarm (Fault Report)

Belt Press Feed Pump - Off (MCCB) Indicator 1 1 Record non-operation hours

Belt Press Feed Pump - To Start/ Stop


Belt Press Feed Pump - Run-hour record

Reset of Hour-Run meter 0 Software record of running

hours Belt Press Feed Pump - Ampere Measure 1 1 Record when operation Belt Press Feed Pump - Voltage Measure 1 1 Record when operation

Belt Press Feed Pump - VSD Parameters Speed Control 1 1 Speed control : RTU via RS-485

Serial Link Belt Press Compressors System Air Compressor - Run Indicator 1 1 Record number of Start / stop Air Compressor - Trip Indicator 1 1 Alarm (Fault Report) Air Compressor - Auto Mode Indicator 1 1 Program Control operation Air Compressor - Manual Mode Indicator 1 1

Air Compressor - To Start/Stop/ Stop Remote Control 1 1 Software control / PLC

Air Compressor - Run-hour record

Reset of Hour-Run meter 0 Software counter running hours

Sludge Cake Conveyor Screen c/v - Run Indicator 1 1 Record number of Start / stop Screen c/v - Trip Indicator 1 1 Alarm (Fault Report) Screen c/v - Auto Mode Indicator 1 1 Program Control operation Screen c/v - Manual Mode Indicator 1 1 Screen c/v - To Start / Stop / Stop Remote Control 1 1

Screen c/v - Run-hour record Reset of Hour-Run meter 0


Belt Backwash Washwater

Pumps

Washwater Pump - Run Indicator 1 1 Record number of Start / stop Washwater Pump - Trip Indicator 1 1 Alarm (Fault Report) Washwater Pump - Auto Mode Indicator 1 1 Program Control operation Washwater Pump - Manual Mode Indicator 1 1

Washwater Pump - To Start / Stop / Stop Remote Control 1 1 Software control / PLC

Washwater Pump - Run-hour record



Polymer Preparation Unit Polymer Mixing - Run Indicator 1 1 Record number of Start / stop Polymer Mixing - Trip Indicator 1 1 Alarm (Fault Report) Polymer Mixing - Auto Mode Indicator 1 1 Program Control operation Polymer Mixing - Manual Mode Indicator 1 1 Polymer Mixing - To Start / Stop Remote Control 1 1 Software control / PLC

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Item






Qty AI

AO DI

DO SCADA Control /

Monitoring

Polymer Mixing - Run-hour record


Software counter / Interlock with screen operation with delay off

Polymer Dilution Skid - Run Indicator 1 1 Record number of Start / stop Polymer Dilution Skid - Trip Indicator 1 1 Alarm (Fault Report)

Polymer Dilution Skid - Auto Mode Indicator 1 1 Program Control operation

Polymer Dilution Skid - Manual Mode Indicator 1 1

Polymer Dilution Skid - To Start/ Stop Remote Control 1 1 Software control / PLC

Polymer Dilution Skid - Run-hour record



Force Ventilation: Sludge Feed & Dewatering Room

Fan : Manual Indicator 1 1 Fan : Auto Indicator 1 1

Fan : Run Indicator 1 1 Status & counter no. of start / stop

Fan : Off Indicator 1 1 Alarm (Fault Report)

Fan : To Start / Stop Remote Start / Stop 1 1

Fan : Run-Hour record Reset of Hour-Run meter 1 Software record of running

hours

Notes:AI = Analog Input AO = Analog Output DI = Digital Input DO = Digital OutputQty = Quantity




234 Volume 4 Malaysian Sewerage Treatment Plant

Attachment C - 3: Representation of SCADA Control Symbols PUMPS & AERATION DEVICES

EQUIPMENT OFF MODE ON MODE

PUMPS

(Centrifugal)

PUMPS (Progressive Cavity)

BLOWER

SURFACE AREATOR

Attachment C - 3: Representation of SCADA Control Symbols

PUMPS & AERATION DEVICES

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Sewage Treatment Plants Third Edition Page 235 Volume 4

ACCESSORIES & FITTINGS

EQUIPMENT OFF MODE ON MODE

Valves

(General)

BUTTERFLY VALVE

AGITATOR

CONVEYORS

CONVEYORS SCREW

ACCESSORIES & FITTINGS




236 Volume 4 Malaysian Sewerage Treatment Plant

OTHERS

EQUIPMENT SYMBOLS

PLC CONTROLLER

WIRELESS COMMUNICATION

SCADA WORKSTATION

POWER TRANSMISSION

METER

COMPRESSOR

TANK

OTHERS

Appendix D

Duty and Standby Requirements

Volume 4

Appendix D - Duty and Standby Requirements


266



Appendix D Duty and Standby Requirements

Table D1 Duty and Standby Requirements for Activated Sludge Systems (Utilising Diffused Aeration)

Table D2 Duty and Standby Requirements for Activated Sludge Systems (Utilising Mechanical Surface Aerator)

Table D3 Duty and Standby Requirements for Rotating Biological Contactor Systems

Table D4 Duty and Standby Requirements for Trickling Filter Systems

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Appendix E

Glossary of Abbreviations

Volume 4

Appendix E - Glossary of Abbreviations


274



Glossary of Abbreviations

ABF Activated Biofilter

AL Aerated Lagoon

AS Activated Sludge

ATU Allyl Thio Urea

BOD Biochemical Oxygen Demand

BOD5 Total Five Day Biochemical Oxygen Demand

CAS Conventional Activated Sludge

CF Certificate of Fitness

CMAL Complete Mixed Aerated Lagoon

CMAS Conventional Mode Activated Sludge

COD Chemical Oxygen Demand

CPR Cardio Pulmonary Resuscitation

DMF Dual Media Filtration

DO Dissolved Oxygen

DOE Department of Environment

DOSH Department of Occupational Safety and Health

DS Deep Shaft

EA Extended Aeration

EAMAS Extended Aeration Mode Activated Sludge

F/M Food to Microorganism ratio

FAL Facultative Aeration Lagoon

FWSP Facultative Waste Stabilisation Ponds

GRP Glass Reinforced Plastic

HAZOP Hazard and Operability Review

HRT Hydraulic Retention Time

HRTF High Rate Trickling Filter

MCRT Mean Cell Residence Time

MLSS Mixed Liquor Suspended Solids

MLVSS Mixed Liquor Volatile Suspended Solids

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MOD Modified Oxidation Ditch

MP Maturation Pond

MS 1228 Malaysian Standard 1228: Code of Practice for Design and Installation of Sewerage Systems

OD Oxidation Ditch

OP Oxidation Pond

OASH Occupational Safety and Health Act

PE Population Equivalent

Qavg Average Flow

Qpeak Peak Flow

QRAS Return Activated Sludge Flow

RAS Return Activated Sludge

RBC Rotating Biological Contactor

SBC Submerged Biological Contactor

SBR Sequential batch Reactor

SIRIM Standards and Industrial Research Institute of Malaysia

SS Suspended Solids

SPAN Suruhanjaya Perkhidmatan Air Negara (National Water Services Commission)

SST Secondary Settlement Tank

STP Sewage Treatment Plant

TDH Total Dynamic Head

TF Trickling Filter

TOL Total Organic Load

VSS Volatile Suspended Solids

WAS Waste Activated Sludge

PRINTED BYPERCETAKAN NASIONAL MALAYSIA BERHADKUALA LUMPUR, 2009www.printnasional.com.myemail: [email protected]: 03-92366895 Fax: 03-92224773

MSIG Volume IV - Sewage Treatment Plant

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Transcript of MSIG Volume IV - Sewage Treatment Plant