Brine-Concentrate Treatment and Disposal Options Report

U.S. Department of the Interior Bureau of Reclamation October 2009

Brine-Concentrate Treatment and Disposal Options Report Southern California Regional Brine-Concentrate Management Study – Phase I Lower Colorado Region

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Contents

Page Abbreviations and Acronyms ................................................................................. vii 1 Introduction and Study Objectives ............................................................... 1

1.1 Introduction ................................................................................................ 1 1.2 Study Objectives ........................................................................................ 3 1.3 Study Components ..................................................................................... 3 1.4 Report Objectives ....................................................................................... 4

2 Volume Reduction Technologies ................................................................... 5 2.1 Electrodialysis/Electrodialysis Reversal .................................................... 5 2.2 Vibratory Shear-Enhanced Processing ....................................................... 9 2.3 Precipitative Softening and Reverse Osmosis .......................................... 13 2.4 Enhanced Membrane Systems ................................................................. 17 2.5 Mechanical and Thermal Evaporation ..................................................... 19 2.6 Natural Treatment Systems ...................................................................... 23

2.6.1 Halophytes .......................................................................................... 23 2.6.2 Constructed Wetlands ........................................................................ 30

2.7 Two-Pass Nanofiltration .......................................................................... 34 2.8 Forward Osmosis ...................................................................................... 35 2.9 Membrane Distillation .............................................................................. 37 2.10 Slurry Precipitation and Reverse Osmosis (SPARRO) ............................ 41 2.11 Advanced Reject Recovery of Water ....................................................... 42 2.12 Capacitive Deionization ........................................................................... 45

3 Zero Liquid Discharge ................................................................................. 47 3.1 Combination Thermal Process with Zero Liquid Discharge .................... 48

3.1.1 Mechanical and Thermal Evaporation ............................................... 48 3.1.2 Crystallizer ......................................................................................... 48 3.1.3 Combination Thermal Process ZLD Systems .................................... 51

3.2 Enhanced Membrane and Thermal System ZLD ..................................... 52 3.3 Evaporation Ponds .................................................................................... 52

3.3.1 Enhanced Evaporation ........................................................................ 56 3.4 Wind-Aided Intensified Evaporation ....................................................... 57 3.5 Dewvaporation ......................................................................................... 58 3.6 Salt Solidification and Sequestration (SAL-PROC) ................................ 59

4 Final Disposal Options ................................................................................. 61 4.1 Deep Well Injection ................................................................................. 61 4.2 Disposal via Wastewater Treatment Facility............................................ 77

4.2.1 Concentrate Blending ......................................................................... 77 4.3 Ocean Disposal ......................................................................................... 77

4.3.1 New Ocean Outfall ............................................................................. 81 4.3.2 Disposal Costs .................................................................................... 82 4.3.3 Considerations for Regulatory Approval ........................................... 83

4.4 Landfill Disposal Option .......................................................................... 85 4.4.1 Introduction ........................................................................................ 85

SOUTHERN CALIFORNIA REGIONAL BRINE-CONCENTRATE MANAGEMENT STUDY – PHASE I BRINE-CONCENTRATE TREATMENT AND DISPOSAL OPTIONS REPORT

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4.4.2 Classification of a Waste .................................................................... 86 5 Energy Generation and Recovery ............................................................... 91

5.1 Energy Generation and Recovery from Brine Concentrate...................... 91 5.2 Co-Siting of Facilities .............................................................................. 91

6 Summary of Technologies ........................................................................... 93 7 References ..................................................................................................... 99

Tables Table 1.1 List of BEMT Members ............................................................................ 1Table 2.1 EDR Capital Cost Matrix .......................................................................... 8Table 2.2 EDR Operation and Maintenance Costs ................................................... 8Table 2.3 VSEP Capital Cost Matrix ...................................................................... 12Table 2.4 VSEP Operation and Maintenance Costs ................................................ 12Table 2.5 PS/RO Capital Cost Matrix ..................................................................... 17Table 2.6 PS/RO Operation and Maintenance Costs .............................................. 17Table 2.7 EMS Capital Cost Matrix ........................................................................ 19Table 2.8 EMS Operation and Maintenance Costs ................................................. 19Table 2.9 MTE Capital Cost Matrix ........................................................................ 22Table 2.10 MTE Operation and Maintenance Costs ................................................. 22Table 2.11 Examples of Halophytic Shrubs, Trees, and Ground Cover ................... 24Table 2.12 Average Seasonal and Annual Class-A Pan Evaporation ....................... 29Table 2.13 Example of Volume Reduction for NTS System During Summer ......... 33Table 3.1 FCC Capital Cost Matrix ........................................................................ 50Table 3.2 FCC Operation and Maintenance Costs .................................................. 51Table 3.3 Conventional ZLD Capital Cost .............................................................. 51Table 3.4 FCC Operation and Maintenance Costs .................................................. 52Table 3.5 Average Seasonal and Annual Class-A Pan Evaporation ....................... 54Table 4.1 Well Injection Capital Cost Matrix ......................................................... 62Table 4.2 Deep Well Injection Operation and Maintenance Costs ......................... 62Table 4.3 Classes of Injection Wells ....................................................................... 68Table 4.4 RO Concentrate Water Quality Examples, Ocean Plan Objectives and

Federal Drinking Water Standards .......................................................... 79Table 4.5 Estimated Outfall Costs ........................................................................... 82Table 4.6 SAWPA Rates for Treatment and Disposal of Non-Reclaimable and

Temporary Domestic Wastewater ........................................................... 82Table 4.7 California Commercial Offsite Industrial Waste Management

Facilities .................................................................................................. 86Table 4.8 Summary of West Basin Municipal Water District Barrier Project

Brine Concentrations .............................................................................. 89


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Figures Figure 1.1 Southern California Study Area ................................................................ 2Figure 2.1 ED/EDR Process ....................................................................................... 6Figure 2.2 Photograph of EDR Unit ........................................................................... 6Figure 2.3 Cake Development in VSEP Versus Conventional Cross-Flow RO ........ 9Figure 2.4 VSEP System and Vibrating Mechanism ............................................... 10Figure 2.5 VSEP Membrane Filter Pack .................................................................. 11Figure 2.6 PS/RO Process Flow Diagram ................................................................ 13Figure 2.7 Typical Solids Contact Clarifier ............................................................. 14Figure 2.8 Typical Thickening Clarifier .................................................................. 14Figure 2.9 Process Flow Diagram of Pilot Pellet Softening .................................... 15Figure 2.10 Process Flow Diagram of Pilot Pellet Softening .................................... 16Figure 2.11 High-Efficiency Reverse Osmosis (HERO) System .............................. 18Figure 2.12 Vertical-Tube Falling-Film Vapor Compression Slurry Seeded

Evaporation Process Flow Diagram ....................................................... 20Figure 2.13 Irrigation Management Strategies Using Concentrate ............................ 27Figure 2.14 Example of Surface Flow and Submerged Aquatic Constructed

Wetlands ................................................................................................. 31Figure 2.15 Salt Marsh Grass Growing Naturally ...................................................... 31Figure 2.16 LBWD Two-Pass NF Pilot Project ......................................................... 34Figure 2.17 Schematic Illustration of RO and FO ..................................................... 35Figure 2.18 Simplified Process Schematic of Forward Osmosis ............................... 36Figure 2.19 Bench-Scale Forward Osmosis Unit at Yale University ......................... 37Figure 2.20 Schematic of Air Gap MD and Air Gap MD with Heat Recovery ......... 39Figure 2.21 Thermal Efficiency and Flux as Function of Salinity ............................. 39Figure 2.22 Conceptual Illustration of SPARRO ....................................................... 41Figure 2.23 Process Flow Schematic of ARROW ..................................................... 43Figure 2.24 New Jersey ARROW Project for Reject Recovery ................................ 44Figure 2.25 CDI Operation (Top) and Regeneration (Bottom) .................................. 45Figure 3.1 Combination Thermal Process with Zero Liquid Discharge System

Schematic ................................................................................................ 48Figure 3.2 Forced Circulation Crystallizer Process Flow Diagram ......................... 49Figure 3.3 Typical Evaporation Pond Configuration of Mechanical Mist

Evaporator ............................................................................................... 56Figure 3.4 WAIV Pilot Unit ..................................................................................... 57Figure 3.5 A Simplified Process Schematic of Dewvaporation ............................... 59Figure 3.6 A Simplified Process Schematic of SAL-PROC™ ................................ 60Figure 4.1 Faults in Ventura County Region ........................................................... 63Figure 4.2 Faults in Los Angeles County Region .................................................... 64Figure 4.3 Faults in Orange County Region ............................................................ 65Figure 4.4 Faults in Inland Empire Area Region ..................................................... 66Figure 4.5 Faults in San Diego County Region ....................................................... 67Figure 4.6 Classes of Injection Wells ....................................................................... 69Figure 4.7 Oil and Gas Wells in Ventura County Region ........................................ 71Figure 4.8 Oil and Gas Wells in Los Angeles County Region ................................ 72


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Figure 4.9 Oil and Gas Wells in Orange County Region ......................................... 73Figure 4.10 Oil and Gas Wells in Inland Empire Area Region .................................. 74Figure 4.11 Oil and Gas Wells in San Diego County Region .................................... 75Figure 4.12 Schematic of a Deep Injection Well ....................................................... 76Figure 4.13 Existing Ocean Outfalls in Southern California ..................................... 78Figure 4.14 Typical Power Plant Outfall Configuration ............................................ 79Figure 4.15 Typical Ocean Outfall Configuration ..................................................... 81Figure 4.16 Flow Process Diagram For Toxicity Characteristic ................................ 88Figure 6.1 Summary of Brine-Concentrate Technology Applicability and

Evaluation Criteria .................................................................................. 94

Attachments Attachment A Halophyte Land Requirements

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Abbreviations and Acronyms °C degrees Celsius

µg/L microgram per liter

µm micrometer

AACE Association for the Advancement of Cost Estimating

AFD axial flow discharge

ARROW Advanced Reject Recovery of Water

AS antiscalant

BEMT Brine Executive Management Team

BOD biochemical oxygen demand

CASO4 calcium sulfate

CCC California Coastal Commission

CCR California Code of Regulations

CDFG California Department of Fish and Game

CDHS California Department of Health Services

CDI Capacitive Deionization

CEC constituents of emerging concern

CEQA California Environmental Quality Act

CFR Code of Federal Regulations

CIMIS California Irrigation Management Information System

CIP clean in place

Cl- chloride

cm/d centimeters per day

CW constructed wetlands

CZMA Coastal Zone Management Act

dS/m deciSiemens per meter

DWI deep well injection


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EC Electrical Conductivity

ECE salinity in soil

ED electrodialysis

EDR electrodialysis reversal

EMS enhanced membrane system

EMWD Eastern Municipal Water District

ET evapotranspiration

FCC forced circulation crystallizer

FO forward osmosis

gfd gallons per square foot per day

gpm gallons per minute

HERO High-Efficiency Reverse Osmosis

HMI human-machine interface

IX ion exchange

kWh kilowatt-hour

LBWD Long Beach Water Department

m molality

m2/g square meters per gram

MD membrane distillation

MF microfiltration

mg/L milligram per liter

mgd million gallons per day

MIT Massachusetts Institute of Technology

mL/L milliliter per liter

MTE mechanical and thermal evaporation

NA+ sodium

NF nanofiltration

NOAA fisheries

National Marine Service Fisheries, a division of the Department of Commerce

NPDES National Pollutant Discharge Elimination System


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NTS natural treatment systems

O&M operations and maintenance

PFD permeating flow discharge

PLC programmable logic controller

PP polypropylene

ppm parts per million

PS precipitative softening

psi pounds per square inch

PTFE polytetrafluoroethylene

pvf polyvinylidene fluoride

Reclamation United States Department of the Interior Bureau of Reclamation

RO reverse osmosis

RWQCB Regional Water Quality Control Board

SAL-PROC Salt Solidification and Sequestration

SAV submerged aquatic vegetation

SAWPA Santa Ana Watershed Protection Authority

SF surface flow

SLC State Lands Commission

SPARRO Slurry Precipitation and Reverse Osmosis

STLC soluble threshold-limit concentration

SWQMP State Water Quality Management Plan

SWQPA State Water Quality Protection Areas

SWRCB State Water Resources Control Board

SWRO seawater reverse osmosis

TCLP toxicity characteristic leaching procedure

TDS total dissolved solids

TSS total suspended solids

TTLC total threshold-limit concentration

TUc Chronic Toxicity Unit


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U.S. United States

UIC underground injection control

USACE United States Army Corps of Engineers

USDW underground source of drinking water

USEPA United States Environmental Protection Agency

USFWS United States Fish and Wildlife Service

V volt

VSEP Vibratory Shear-Enhanced Processing

WAIV Wind-Aided Intensified Evaporation

WETCAT Wetlands Capture and Treatment

WMWD Western Municipal Water District

WWTP wastewater treatment plant

ZLD zero liquid discharge

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1 Introduction and Study Objectives This section of the report has the following subsections:

Introduction Study Objectives Study Components Report Objectives

1.1 Introduction

The Southern California Regional Brine-Concentrate Management Study is a collaboration between the United States (U.S.) Department of the Interior Bureau of Reclamation (Reclamation) and 14 local and state agency partners. Table 1.1 provides a list of the agencies represented on the Brine Executive Management Team (BEMT). The project is funded on a 50/50 cost-sharing basis between Reclamation and the cost-sharing partners, who together form the BEMT. The purpose of the BEMT is to formulate, guide, and manage technical activities of the study. Figure 1.1 shows a map of the study area.

TABLE 1.1 LIST OF BEMT MEMBERS

List of BEMT Members

City of San Bernardino Orange County Sanitation District

California Department of Water Resources Otay Water District

City of San Diego Rancho California Water District

Inland Empire Utilities Agency San Diego County Water Authority

Sanitation Districts of Los Angeles County Santa Ana Watershed Project Authority

Los Angeles Department of Water and Power U.S. Department of the Interior Bureau of Reclamation

Metropolitan Water District of Southern California

Western Municipal Water District

National Water Resources Institute/ Southern California Salinity Coalition

Hemet

Oxnard

Perris

Irvine

Ontario

Banning

Anaheim

Fillmore

El Cajon

Redlands

Hesperia

Elsinore

Torrance

Glendale

San Diego

Encinitas

Escondido

Oceanside

Riverside

Lancaster

Long Beach

Victorville

Carpinteria

Los Angeles

Port Hueneme

Apple Valley

Palm Springs

San Clemente

Thousand Oaks

Big Bear Lake

Santa Barbara

FIGURE 1.1 - SOUTHERN CALIFORNIA STUDY AREASOUTHERN CALIFORNIA REGIONAL BRINE-CONCENTRATE MANAGEMENT STUDY - PHASE I ±

\\cheron\projects\USBR\381333BrineStudy\GIS 08/25/2009

San DiegoCounty Region

NorthOrange County

Region

Inland EmpireRegion

SouthOrange County

Region

Los Angeles County Region

Ventura CountyRegion

Boundaries

Study Area

California/Mexico Border

Features

Major Cities

Highways

Rivers

Water Bodies

Mexico

California

0 10 20Miles



1.2 Study Objectives

The objectives of this study are twofold:

• To assess the brine-concentrate landscape in southern California including brine-concentrate management technologies, regulatory environment, existing infrastructure, and future needs

• To make recommendations for Phase 2 pilot/demonstration projects

To accomplish these objectives, the study will develop six reports that ultimately will be incorporated into a final study report.

1.3 Study Components

The Southern California Regional Brine-Concentrate Management Study has six major components. Each component is focused on providing a piece of the southern California brine-concentrate management landscape. Each component will be summarized in a draft report that will be incorporated into the Final Study Report. The six components of the study are:

• Survey Report – A regional survey to collect data from local agencies about the brine-concentrate landscape in southern California

• Regulatory Issue and Trends Report – A summary of regulatory issues and trends associated with implementing a brine-concentrate project in southern California

• CECs Report – A summary of constituents of emerging concern (CECs) and how regulation of CECs might affect brine-concentrate management in southern California

• Institutional Issues Report – A summary of organizational structures that can be used to foster collaborative relationships between agencies implementing brine-concentrate management projects

• Brine-Concentrate Management Treatment and Disposal Options Report – A summary of brine-concentrate technologies and identification of potential local and regional solutions

• Pilot/Demonstration Project Recommendations Report – A list of recommended pilot/demonstration projects that could be implemented in the inland and coastal areas southern California

These six reports will be incorporated as appendices in the Final Study Report. The Final Report will provide highlights and conclusions of the six component reports in an executive summary format.



1.4 Report Objectives

There are a number of technologies that can be used for brine-concentrate management. The objective of this report is to describe and evaluate these technologies. The evaluation categorizes concentrate disposal technologies into three broad groups—volume reducing, zero liquid discharge, and final disposal technologies. The evaluation of each technology consists of:

• Description of the technology • Advantages and disadvantages associated with the technology • Capital and operations and maintenance (O&M) costs for the technology

The performance and limitations associated with each of the technologies are based on pilot, bench- and full-scale data and information obtained from vendors. Cost information about the technologies was obtained from equipment manufacturers and experience with project implementation.

The cost estimates provided in this section will be conceptual cost estimates or Class 5 estimates in accordance with the Association for the Advancement of Cost Estimating (AACE). An AACE defines order-of-magnitude costs as Class 5 cost estimates without detailed engineering data. Examples of order-of-magnitude cost estimates include:

• An estimate from cost capacity curves • An estimate using scale-up or scale-down factors • An approximate ratio estimate

The estimates shown, and any resulting conclusions on the financial or economic feasibility or funding requirements of a concentrate management option, have been prepared to guide evaluation and implementation of the project based on information available at the time of the cost estimate. The expected accuracy ranges for a Class 5 cost estimate are –15 to –30 percent on the low side and +20 to +50 percent on the high side. The final costs of the project and resulting feasibility will depend on actual labor and material costs, competitive market conditions, actual site conditions, scope of the final project, implementation schedule, continuity of personnel and engineering, and other variable factors. As a result, the final cost estimates will vary from the estimates presented in this report.

This report will provide data on energy generation and recovery including co-location of facilities, energy generation from concentrate, and energy recovery mechanisms.


2 Volume Reduction Technologies Volume reduction technologies are designed to reduce size and cost of the ultimate concentrate facilities. Because the technologies produce a liquid residual stream, they are often named liquid-residual-producing processes. Depending upon the water quality and technology used, volume reduction technologies can reduce concentrate volumes by up to 90 percent. After the volume of concentrate is reduced using one of these technologies, an additional process is required to completely dispose of the concentrate either by solidifying the concentrate product or discharging the liquid concentrate. The volume reduction technologies that are available include:

• Electrodialysis/Electrodialysis Reversal • Vibratory Shear-Enhanced Processing • Precipitative Softening and Reverse Osmosis • Enhanced Membrane System • Brine Concentrator • Natural Treatment Systems

Other technologies that are not available in US market and under development include:

• Two Pass Nanofiltration • Forward Osmosis • Membrane Distillation • Slurry Precipitation and Reverse Osmosis • Advanced Reject Recovery of Water • Capacitive Deionization

The following subsections provide a summary of the volume reduction technologies.

2.1 Electrodialysis/Electrodialysis Reversal

Electrodialysis (ED) is a process that uses an electrical current to remove salt ions from a solution. The ED technology is based on the property that salts in solution are dissociated into positively and negatively charged ions. The key to the ED process is a semipermeable barrier that allows passage of either positively charged ions (cations) or negatively charged ions (anions) but excludes passage of ions of the opposite charge. These semipermeable barriers commonly are known as ion-exchange (IX), ion-selective, or electrodialysis membranes. Figure 2.1 is a simplified representation of the ED/Electrodialysis Reversal (EDR) process, illustrating how the positively charged ions (for example, sodium [Na+]) in the influent are pulled across the cation-transfer membrane toward the cathode, and the



negatively charged ions (for example, chloride [Cl-]) are pulled across the cation-transfer membrane toward the anode. Figure 2.2 is a photograph of an EDR unit. The selective removal of cations and anions produces a concentrate stream and a demineralized product stream. Because the product water does not pass through a membrane barrier, the California Department of Health Services (CDHS) does not recognize ED/EDR as a barrier process for turbidity and pathogen removal.

FIGURE 2.1 ED/EDR PROCESS

Source: GE Water and Process Technologies

FIGURE 2.2 PHOTOGRAPH OF EDR UNIT

Source: GE Water and Process Technologies



EDR is effective for feedwaters with total dissolved solids (TDS) measuring up to 8,000 parts per million (ppm). This technology has been used for potable water and for wastewater applications but does not have a proven history in dealing with brine concentrate from recycled water applications. Advantages associated with EDR include the following:

• Potential for higher recovery than other membrane processes.

• Lower fouling potential because nonionic contaminants (particulates) are not driven to the membrane surface by the flow of water through the membranes (as in reverse osmosis [RO]). Also, the use of polarity reversal is used to electrically displace foulants from the membrane and electrode surfaces on a frequent basis.

Potential disadvantages of EDR include the following:

• Inability to remove all constituents (such as, boron, silica, and uncharged micropollutants).

• Effectiveness is achieved only when TDS concentration in the feedwater is less than 8,000 ppm.

• CDHS does not recognize EDR as a water treatment technology because EDR does not provide a barrier against pathogens.

• Multiple stages are required for treatment of high-TDS feedwater, such as concentrate, which increases capital and O&M costs.

Capital costs for an EDR unit capable of handling 1 million gallons per day (mgd) of flow range from approximately $5,200,000 for a unit capable of handling brine concentrate flows with TDS measuring 5,000 ppm, as seen in Table 2.1. Cost estimates are based on information provided by Ionics1

The cost estimates provided for EDR and other technologies presented in this section (Section 2) and Section 3 are conceptual cost estimates or Class 5 estimates in accordance with the Association for the Advancement of Cost Estimating (AACE). An AACE defines order-of-magnitude costs as Class 5 cost estimates without detailed engineering data. Examples of order-of-magnitude cost estimates include:

for a 1.0-mgd system.

• An estimate from cost capacity curves • An estimate using scale-up or scale-down factors • An approximate ratio estimate

The estimates shown, and any resulting conclusions on the financial or economic feasibility or funding requirements of a concentrate management option, have been prepared to guide project evaluation and implementation from the information available at the time of the cost estimate. The expected accuracy ranges for a Class 5 cost estimate are –15 to –30 percent on the low side and +20 to +50 percent on the high side. The final costs of the project and resulting feasibility will depend on actual labor and material costs, competitive market conditions, actual site conditions, scope of the final project, implementation schedule, continuity of personnel and

1 Currently, only one vendor of EDR is in the United States..



engineering, and other variable factors. As a result, the final cost estimates will vary from the estimates presented in this report.

There are a number of assumptions that are common to each concentrate management option cost estimate, these include:

• Neither engineering nor legal and land/easement acquisition were included in the analysis

• Electricity unit cost is $0.12 per kilowatt (kW)

• Total capital cost includes 25 percent contingency. This contingency was applied to account for any changes and uncertainties in market conditions.

• A new full-time operation staff would be a Class II certified operator, paid approximately $90,000 per year.

Assumptions that were used to develop the cost estimates for EDR include:

• Recovery of 85 percent assuming a concentrate feed with a TDS concentration of 5,000 ppm

• A three-stage system to meet TDS of less than 500 mg/L in product water. TABLE 2.1 EDR CAPITAL COST MATRIX

0.2 mgd 1.0 mgd 5.0 mgd

Total Capital Cost Including Equipment Installation and Building to House the Equipment, $

$1,550,000 $5,196,000 $15,032,000

Note: Capital costs for 1.0-mgd system is according to the City of Santa Maria, 2009. Cost for other flow rates were estimated using the following formula: Cost 2 = (Flow 2/Flow 1)^0.66*Cost 1. (Flow 1 is 1.0 mgd).

A breakdown of projected annual O&M costs for a 1-mgd facility is shown in Table 2.2. The O&M costs include power, labor, antiscalant and acid addition to feed water, membrane replacement every 5 years, annual electrode replacement, chemical cleaning, and routine maintenance and replacement of parts. TABLE 2.2 EDR OPERATION AND MAINTENANCE COSTS

Cost Component O&M Cost, $/yr

Power $307,000

Labor $90,000

Parts and Maintenance $215,000

Chemicals and Consumables $302,000

Total $914,000



2.2 Vibratory Shear-Enhanced Processing

Conventional membranes are subject to colloidal fouling because suspended material can become polarized at the membrane surface and obstruct filtration. Vibratory Shear-Enhanced Processing (VSEP), a patented process of New Logic Research, Inc., was developed to reduce polarization of suspended colloids on the membrane surface by introducing shear to the membrane surface through vibration. Shear waves produced on the membrane surface keep the colloidal material in suspension, thereby minimizing fouling. As a result, high throughput and water recoveries above that of a conventional membrane system can be achieved.

VSEP employs torsional oscillation at a rate of 50 times per second (50 hertz) at the membrane surface to inhibit diffusion polarization of suspended colloids. The suspended colloids are helped in suspension where a tangential cross flow washes them away. Figure 2.3 compares cake formation on the membrane surfaces of conventional and VSEP membrane systems.

FIGURE 2.3 CAKE DEVELOPMENT IN VSEP VERSUS CONVENTIONAL CROSS-FLOW RO

Source: New Logic Research, Inc.



VSEP consists of four components—a driving system than generates vibration, a membrane module, a torsion spring that transfers vibration to the membrane module, and a system for controlling vibration. The vibration imparts a shear to the surface of the membrane to mitigate fouling and scaling that would occur in a conventional RO system (Figure 2.4). The membrane module houses a stack of flat membrane sheets (filter pack) in a plate-and-frame-type configuration as shown in Figures 2.4 and 2.5.

FIGURE 2.4 VSEP SYSTEM AND VIBRATING MECHANISM




FIGURE 2.5 VSEP MEMBRANE FILTER PACK


Unlike the conventional RO membranes, VSEP performance is not limited by the presence of colloidal material. The VSEP system can be configured employing either RO or nanofiltration (NF) membranes in a single-stage or multiple-stage arrangement. The configuration depends upon water quality goals for the VSEP permeate, as well as target water recovery. VSEP has not been used in a full-scale concentrate application; however, the process has been used in agricultural and industrial applications. Advantages associated with VSEP include:

• Potentially high recovery rates

• Production of high-quality water (similar to conventional RO)

• Minimal environmental issues associated with use (similar to traditional membrane systems)

• Potentially no requirement for pretreatment chemicals (such as antiscalant and feedwater pH adjustment)

Disadvantages associated with VSEP include:

• No experience in municipal applications

• Performance needs to be evaluated through pilot testing

• Potentially susceptible to amorphous fouling with aluminum, iron and manganese oxide deposits

• Much higher clean-in-place (CIP) frequencies than conventional RO (BBARWA, 2006) due to operating with much higher fluxes (i.e., 24-30 gfd vs. 9-12 gfd).

• Changing all membrane elements in a stack is required if one membrane plate needs replacement

• Higher capital and O&M costs than traditional RO

• Proprietary technology from a single vendor

• Sound attenuation technology typically required



Capital costs for a VSEP unit capable of handling 1 mgd of flow range from approximately $5.7 million for a flow with a TDS of 5,000 ppm and a silica concentration of 60 mg/L. These estimates are based on information provided by New Logic Research, Inc., the developer of VSEP technology. Capital cost estimates for three different capacities, are provided in Table 2.3. Assumptions that were used to develop the cost estimates for VSEP include:

• A two-stage VSEP with a recovery of 75 percent (concentrate silica concentration exceeding 100 mg/L reduces recovery rate of VSEP to less than 65 percent which is not desirable. To improve recovery of the system, a pretreatment necessary to reduce silica level to 60 mg/L or less in the feed water).

• VSEP needs special equipment for maintenance including a 2-ton hoist for filter module replacement.

• A building to house the equipment.

• Unit size and power requirements were estimated assuming a 2,000-gallon per minute (gpm) (2.9-mgd) flow.

TABLE 2.3 VSEP CAPITAL COST MATRIX

0.2 mgd 1.0 mgd 5.0 mgd


$1,699,600 $5,698,000 $16,485,000

Note: Capital costs for 1.0-mgd system is according to the City of Santa Maria, 2009. Cost for other flow rates were estimated using the following formula: Cost 2=(Flow 2/Flow 1)^0.66*Cost 1. (Flow 1 is 1.0 mgd).

A breakdown of annual O&M costs for a 1-mgd facility is shown in Table 2.4. The projected O&M costs include power, labor, feed water acidification, biannual membrane replacement, chemical cleaning and routine maintenance and replacement of parts.

TABLE 2.4 VSEP OPERATION AND MAINTENANCE COSTS

O&M Cost, $/yr

Power $182,704

Labor $62,400

Parts and Maintenance $610,695

Chemicals and Consumables $52,560

Total $908,359



2.3 Precipitative Softening and Reverse Osmosis

Precipitative softening (PS) is a unit process that can be integrated with the RO system to increase recovery of concentrate as a volume-reduction process. PS works to increase the recovery rate of the RO process by controlled precipitation and removal of sparingly soluble inorganic salts. The PS unit process includes chemical addition and clarification for softening (that is, alkalinity and hardness removal) and pH adjustment for silica removal.

Inorganic salt precipitation can be controlled at lower recoveries by using an appropriate antiscalant and by lowering the pH of feedwater. At higher recoveries, antiscalants are not as effective and pH control does not prevent precipitation of problematic minerals such as barium sulfate and calcium sulfate, which are difficult to remove by chemical cleaning. In addition, silica scaling is problematic at lower pH values, the opposite of calcium carbonate scale, which precipitates more readily at high pH values (Johnson, 2001). The PS process is effective at removing calcium, barium, and strontium (primary scale-forming ions). Silica removal also can be performed by PS if the pH is elevated by adding magnesium and/or sodium hydroxide to increase the pH to 10.3 or higher.2

A process flow diagram for a PS process is presented in Figure 2.6, and an example of a typical solids contact clarifier is shown in Figure 2.7. Alternatively, a high-rate contact clarifier

/

FIGURE 2.6 PS/RO PROCESS FLOW DIAGRAM

thickener (Figure 2.8) could be used to treat the sludge in the PS step, eliminating the need for separate gravity thickening.

Solids ContactClarifier

MicrofiltrationSystem

Reverse OsmosisSystemRO Concentrate RO Concentrate

ROPermeate

Dewatered Sludge toDisposal

Gravity ThickenerSludge Dewatering

MF Concentrate

2 Based on Ft. Irwin Concentrate Recovery Jar Testing Results



FIGURE 2.7 TYPICAL SOLIDS CONTACT CLARIFIER

Source: Infilco Degremont Accelerator

FIGURE 2.8 TYPICAL THICKENING CLARIFIER

Source: Infilco Degremont DensaDeg High Rate



An alternative technology to softening step of conventional PS/RO is the pellet softening. In this process, hardness can be removed from the water by growth of calcium carbonate crystals in a fluidized bed reactor, or pellet reactor. With the use of sand and grains as seeds, the removal efficiency of hardness can be increased. Unlike the sludge produced from the conventional softening plant, a crystallization process in a fluidized reactor produces solid grain of calcite. These pellets have an economic value that can be used in agricultural and industrial fields. Western Municipal Water District (WMWD) successfully pilot tested this technology at the Arlington Desalter in Riverside County, California. The purpose of testing was to show if this technology reduces the scale forming mineral thereby reducing scale formation in SARI line. Figure 2.9 illustrates the process flow diagram of a pilot pellet softening facility at the Arlington Desalter. Figure 2.10 illustrates the pilot unit and pellets formed.

FIGURE 2.9 PROCESS FLOW DIAGRAM OF PILOT PELLET SOFTENING

Source: Safely, 2009



FIGURE 2.10 PROCESS FLOW DIAGRAM OF PILOT PELLET SOFTENING

Source: Safely, 2009

The PS/RO process is a proven technology for municipal and industrial applications and can be installed in existing chemical- and sludge-handling facilities. Combined PS/RO systems are manufactured by a number of companies and have similar regulatory requirements to traditional RO systems. However, the combined PS/RO systems have a large overall footprint and might require additional chemical and sludge dewatering facilities. Environmental impacts include high usage of chemicals based on the feed quality and management of sludge disposal. Advantages associated with PS/RO include:

• Proven technology treatment train – many installations with RO following PS or lime softening

• Applicable to concentrate with high silica content

• Regulatory issues similar to RO

Disadvantages associated with PS/RO include:

• Large overall footprint

• Additional space required for chemical facilities and dewatering of sludge

• High usage of chemicals depending on feedwater quality

• Management of sludge disposal required

• Overall recovery limited by RO system osmotic pressure constraints



Estimates for the cost of a combined PS/RO system include capital costs for sludge dewatering and for chemical facilities, and are based on information provided by Infilco Degremont. The projected capital costs for a PS/RO unit are $13 million for a 1-mgd PS/RO unit. However, this cost can be reduced if sludge dewatering is not required. Table 2.5 summarizes the capital costs for the PS/RO system.

TABLE 2.5 PS/RO CAPITAL COST MATRIX 0.2 mgd 1.0 mgd 5.0 mgd


$4,495,000 $13,000,000 $33,608,000

Note: Capital costs for 1.0-mgd system is according to the City of Santa Maria, 2009. Cost for other flow rates were estimated using the following formula: Cost 2=(Flow 2/Flow 1)^0.66*Cost 1. (Flow 1 is 1.0 mgd).

A breakdown of annual O&M costs for a 1-mgd facility treating is shown in Table 2.6. O&M costs include power, labor, sludge disposal, chemicals for softening, pH adjustment and for CIP, membrane replacement costs (every 3 years), routine maintenance and other replacement of system parts.

TABLE 2.6 PS/RO OPERATION AND MAINTENANCE COSTS

Component O&M Cost, $/year

Power $274,000

Parts $150,000

Chemicals $350,000

Maintenance $121,000

Sludge Disposal $51,000

Labor $90,000

Total O&M Cost, $/year $1,036,000

2.4 Enhanced Membrane Systems

An Enhanced Membrane System (EMS) is used to reduce the volume of reject concentrate by increasing the recovery of the RO process. One type of EMS is the patented High-Efficiency Reverse Osmosis (HERO) system (Figure 2.11). This process involves IX softening of reject from a first-phase membrane system to reduce the scaling potential of the concentrate fed to the HERO system, a degasification step to remove carbon dioxide, and addition of a caustic that would increase pH (about 11) to retard silica scaling and biofouling. The process combines a two-phase RO process with chemical pretreatment of primary RO, intermediate IX



treatment of primary RO concentrate, and high pH operation of secondary RO. The secondary RO step operates at high efficiency due to IX pretreatment and operations at a high pH. This process results in a higher recovery than standard RO systems.

EMS is a relatively new type of membrane system and might require detailed pilot testing prior to implementation. Pilot testing could be complex due to the need to generate concentrate from a mainstream feedwater RO unit for the EMS pilot unit.

Advantages associated with EMS include:

• Applicable to concentrate flows with high silica content

• Relatively small foot-print

• Higher recovery achievable than with conventional RO because feed hardness is removed

• Small aesthetic profile (no tall stacks)

Disadvantages associated with EMS include:

• Inefficiency due to TDS limitations

• High capital and O&M costs

• Highly skilled operations staff required

• Complex process control system runs the IX, pH adjustment, and RO systems

• Produces two concentrated waste streams, IX regenerate, and HERO reject

• Waste streams form voluminous precipitate when combined FIGURE 2.11 HIGH-EFFICIENCY REVERSE OSMOSIS (HERO) SYSTEM

Source: Aquatech, 2009



Estimated capital costs are summarized in Table 2.7. Capital costs for an EMS unit capable of handling 1-mgd flow range from approximately $7.8 million for a flow with TDS of 3,000 ppm to approximately $9 million for a flow with TDS of 8,000 ppm. TABLE 2.7 EMS CAPITAL COST MATRIX 0.2 mgd 1.0 mgd 5.0 mgd


$4,636,000 $15,540,000 $37,018,000

Note: Capital costs for 0.2-mgd system is according to BBARWA, 2006. Cost for other flow rates were estimated using the following formula: Cost 2=(Flow 2/Flow 1)^0.66*Cost 1. (Flow 1 is 0.2 mgd).

Table 2.8 summarizes the O&M costs for a facility with 1 mgd of feedwater flow and 8,000 mg/L TDS. O&M cost information is based on “Evaluation of RO Concentrate Management Options for Big Bear Area Regional Wastewater Agency” CH2M HILL, 2005. O&M costs include power, labor, chemicals for pH adjustment and for CIP, membrane replacement costs (every 5 years), and ion exchange resin replacement costs (every year). TABLE 2.8 EMS OPERATION AND MAINTENANCE COSTS


Power $263,000

Parts $163,000

Chemicals $263,000 Maintenance $148,000

Labor $90,000 Total O&M Cost, $/year $927,000

2.5 Mechanical and Thermal Evaporation

Mechanical and thermal evaporation devices are energy-intensive processes used to reduce the volume of concentrate by boiling the liquid and recover purified distillate. For mechanical evaporation, heat is added to the concentrate by a mechanical adiabatic heating process. For thermal evaporation, steam is used to heat the concentrate. The absorbed heat causes water to vaporize, which reduces the concentrate volume. The vapor is condensed, becoming distillate for reuse.

A number of different configurations of evaporators are supplied by different vendors. Evaporators are classified according to the arrangement of their heat transfer surfaces and the method used to impart heat to the feed solution. Common types of evaporators include single or multiple effect, vapor compression,



vertical-tube falling-film, horizontal-tube spray-film, and forced circulation types. Figure 2.12 is a flow process diagram for a vertical tube, falling film, vapor compression evaporator (brine concentrator). A distinction is also made between conventional mechanical evaporation and slurry-seeded systems. FIGURE 2.12 VERTICAL-TUBE FALLING-FILM VAPOR COMPRESSION SLURRY SEEDED EVAPORATION PROCESS FLOW DIAGRAM

MembraneReject

ProductWater

Vapor

BrineSlurry

BrineConcentrate to

Evaporator/Crystallizer

1

2

4

5

7

3

6

Note: Numbers correspond with description in text.

The following process steps are numbered to correspond with the numbers in the process diagram.

The following process steps are numbered to correspond with the numbers in the process diagram.

1. Membrane reject is pumped through a feed-distillate heat exchanger that raises the temperature of the membrane reject and cools the distillate.

2. The hot membrane reject combines with the concentrate slurry (solid phase is anhydrous calcium sulfate) in the sump. The concentrate slurry is circulated constantly from the sump to the floodbox at the top of a bundle of heat transfer tubes. Calcium sulfate crystals that precipitate as feed is concentrated act as precipitation nuclei to prevent scaling on the heat transfer surfaces.

3. Some of the concentrate evaporates as it flows in a falling film through the tubes and back into the sump.



4. The vapor passes through mist eliminators and enters the vapor compressor, which heats the vapor. The compressed vapor is desuperheated with hot distillate and condenses into liquid water on to the outside of the heat transfer tubes. Mechanical compressors are used in most applications. The mechanical vapor compressor is responsible for about 80 percent of the 70- to 90-kilowatt-hour (kWh) energy usage per 1,000 gallons of brine concentrator feed.

5. Water vapor condenses on the surface of heat transfer tubes, transferring heat to the slightly cooler concentrate falling inside the tubes. Transferred heat causes more of the concentrate to evaporate, thereby sustaining the cycle.

6. As the compressed vapor gives up heat, the vapor condenses into distilled water. The distillate is relatively uncontaminated and typically has a TDS concentration of 5 to 10 mg/L, making the distillate an excellent source of water.

7. The high-purity distillate is pumped through the feed-distillate heat exchanger, where the distillate gives up heat to the incoming membrane reject water and the distillate is cooled. Total recovery of product water across the concentrator may range from less than 90 to over 99 percent, depending on water chemistry.

8. From less than 1 to over 10 percent of the concentrate slurry is blown down from the sump to maintain the concentrate Total Solids (TS) (dissolved and suspended) between 20 and 30 percent (200,000 to 300,000 mg/L). Blowdown may be sent to a crystallizer feed tank and then sent to the forced circulation crystallizer. Alternatively, the blowdown can be sent to an evaporation pond.

Mechanical evaporators are a proven technology for reduction of concentrate volume in industrial applications and can handle a range of feedwater compositions. Mechanical evaporators have a small site footprint with a tall tower profile that could affect its location due to height restrictions or aesthetic issues. Mechanical evaporators are complex and require specialized labor skills for operation and maintenance. The total solids concentration of the MTE brine is typically between 200,000 and 300,000 mg/L TS.

Advantages associated with mechanical evaporators include:

• Proven technology for brine concentrate volume reduction in industrial applications

• A small site footprint

• Most organic and inorganic constituents removed and high-quality water produced



Disadvantages associated with mechanical evaporators include:

• High capital and O&M costs due to mechanical complexity and high energy demands

• Sound enclosures possibly needed

• Aesthetics associated with tall tower profile

• Not feasible for projects with specific height limits (i.e., 50 ft or less).

Estimated capital costs for a mechanical evaporation unit are summarized in Table 2.9. Capital cost estimates are based on vendor data for the brine concentrator produced by Ionics (now part of GE Water). Capital costs for a 1-mgd MTE unit are approximately $17.7 million. Capital costs are independent of the TDS concentration.

TABLE 2.9 MTE CAPITAL COST MATRIX

0.2 mgd 1.0 mgd 5.0 mgd

Total Capital Cost Including Equipment Installation , $ $5,280,000 $17,698,000 $51,196,000

Note: Capital costs for 0.2-mgd system is according to BBARWA, 2006. Cost for other flow rates were estimated using the following formula: Cost 2=(Flow 2/Flow 1)^0.66*Cost 1. (Flow 1 is 0.2 mgd.)

Table 2.10 provides O&M cost estimates for a MTE unit. O&M costs include power, labor, chemicals, maintenance, and replacement costs for key equipment components (i.e., compressor, heat exchanger). These estimates were provided by Ionics and are based on a 1-mgd feed flow. TABLE 2.10 MTE OPERATION AND MAINTENANCE COSTS


Power $4,000,000

Parts $885,000

Chemicals $250,000


Labor $180,000




2.6 Natural Treatment Systems

Natural treatment systems are an established technology for polishing and treatment of wastewater effluent but have not been used widely as a method of RO concentrate disposal. Several pilot studies have been developed in Oxnard, California, as well as in Brisbane, Australia, and Goodyear, Arizona. There are two configurations of NTS that are evaluated in this report:

• Halophytes in a closed system to uptake the concentrate prior to final disposal • Constructed wetlands to treat the concentrate stream prior to final disposal

Both of these systems use natural processes to remove salt and other constituents from the concentrate as a cleaning step before final disposal.

2.6.1 Halophytes Halophytes are broadly defined as plants with an unusually high tolerance to salinity; however, the lower limit of salt tolerance is poorly defined (Glenn, 1999). Halophytes thrive in saline conditions, such as in marine estuaries and salt marshes, through cellular, tissue, and whole plant adaptations (Glenn, 1999). Many of these plants have adapted to a saline environment by absorbing large amounts of salt with water, while others have exclusion mechanisms of adaptation. Halophytes tolerate salinity largely via the controlled uptake of sodium (balanced by chloride and other anions) into cell vacuoles to produce an electrochemical gradient that drives water into the plant when external water potential is low (Glenn, 1999). Other secondary tolerance mechanisms include presence of salt glands, salt bladders, or succulent tissues; and whole plant reduction of stomatal conductance, thereby increasing water use efficiency in response to salt. However, individual plants will vary in the traits that they possess to the extent in which they are used (Seaman, 2004).

Halophytes can be used as a brine/concentrate management technology in the same manner as an NTS (wetland). The use of wetlands and halophytes for brine/concentrate management is an emerging technology; however, both are accepted treatment technologies for stormwater and wastewater applications. The salinity threshold of salt tolerant plants varies depending on plant type, with halophytes having an extremely high salinity threshold. Examples of salt tolerant and halophytic plants are shown in Table 2.11. Salinity thresholds are provided as electrical conductivity (ECe). At moderate salinity levels, EC can be related to TDS through the following relationship:

TDS (mg/L) = 640 x EC (dS/m)



TABLE 2.11 EXAMPLES OF HALOPHYTIC SHRUBS, TREES, AND GROUND COVER

Common Namea Botanical Name Max Permissibleb ECe; dS/m

Moderately Tolerant -

Weeping bottlebrush Callistemon viminalis 6-8

Oleander Nerium oleander 6-8

European fan palm Chamaerops humilis 6-8

Blue dracaena Cordyline indivisa 6-8

Rosemary Rosmarinus officinalis 6-8

Aleppo pine Pinus halepensis 6-8

Sweet gum Liquidamabar styraciflua 6-8

Tolerant -

Brush cherry Syzygium paniculatum >8 c

Ceniza Leucophyllum frutescens >8 c

Natal plum Carissa grandiflora >8 c

Evergreen Pear Pyrus kawakamii >8 c

Bougainvillea Bougainvillea spectabilis >8 c

Italian stone pine Pinus pinea >8 c

Very Tolerant -

White iceplant Desloperma alba >10 c

Rosea iceplant Drosanthemum hispidum >10 c

Purple iceplant Lampranthus productus >10c

Croceum iceplant Hymenocyclus croceus >10c

Notes: aSpecies are listed in order of increasing tolerance based on appearance and growth reduction. bSalinities exceeding the maximum permissible ECe could cause leaf burn, loss of leaves, and/or excessive stunting. cMaximum permissible ECe is unknown. No injury symptoms or growth reduction was apparent at 7 dS/m. The growth of all iceplant was increased by soil salinity of 7 dS/m. Source: Maas, 1990.



Irrigation of Halophytes Halophyte irrigation is one of the areas recommended for additional research and development effort by the AWWA subcommittee on concentrate management (AWWA, 2004). Halophyte applications include landscaping, wildlife habitat, dust barriers, windbreaks, livestock grazing, and production of grains, oilseeds, and fodder (Ahuja, 2005). Internationally, the United Arab Emirates has extensively investigated halophyte systems for landscaping, crop, and livestock production, golf course irrigation, landscaping, and creating nature preserves (Child, 2005).

There are numerous implementation issues that require consideration when irrigating with brine, including

• Overall irrigation strategy and distribution techniques • Opportunities for blending irrigation water sources • Chemical characteristics of the brine and ultimate fate of chemical constituents • Hydraulic and nutrient loading • Site and plant selection • Site drainage characteristics • Leaching requirement and potential groundwater impacts • Seasonal storage requirements/discharge alternatives (Jordahl, 2006)

Plant limitations and need for substantial leaching, water quality considerations and regulatory restrictions for both surface and ground waters, and cost all limit the feasibility for large-scale implementation of brine irrigation projects. Some of these are described in more detail below.

Plant Species Halophytes generally perform best when the soil solution salinity is ≤ 20 grams per liter (g L-1), which is less saline that the brine concentrate produced with some treatment technologies (Miyamoto, 1996). Certain halophyte plant species, however, such as Salicornia spp., can tolerate irrigation with seawater (about 35 g L-1). When TDS of the concentrate is above the highest value that can be tolerated by vegetation, irrigation is not a feasible alternative without blending. If the plant species can tolerate the concentrate salinity and is otherwise suitable for the geographic area and soil conditions, then irrigation may be a viable alternative for disposing of membrane concentrate (Jordahl, 2006).



Individual halophyte species may show differences in salt tolerance, depending on growth stage. For example, many halophytes show a 50 percent reduction in seed germination when solution salinity is about 10 g L-1, which is similar to the germination reduction that is observed with many conventional crops (Miyamoto, 1996). On the other hand, Salicornia spp. will germinate readily in seawater (Miyamoto, 1996). Therefore, it is important to consider plant salinity thresholds at all life stages that would be affected by brine irrigation, and to use blending or other water sources when necessary to prevent adverse salinity impacts.

During the rainy season, halophytes would likely obtain most of their needed water from precipitation; and plant capacity to use brine flows may differ from the volume of flows that is produced. Installation of detention ponds may be necessary to detain excess water when the rate of brine production exceeds the allowable hydraulic loading rate (Jordahl, 2006).

Irrigation Management Strategy Three methods of managing brine irrigation could be considered (Jordahl, 2006) and are illustrated in Figure 2.13:

• Storage in the vadose zone. This method requires a deep water table and careful management to apply a limited leaching fraction, and effectively store salts in the vadose zone. Problems can arise if salts precipitate and form a slowly permeable layer that would retard drainage (e.g., a caliche layer). Riley et al. (1998) calculated that with a 3 to 5 percent leaching fraction applied to halophytic vegetation, it would taken 100 years of irrigation for percolation to reach half-way to the depth of the water table at a site in southern Arizona (Riley, 1998).

• Volume Reduction. This irrigation method reduces the concentrate volume through evapotranspiration, and requires a subsurface drainage system to recapture the concentrate. To ensure protection of groundwater quality, presence of slowly permeable subsoil underlying subsurface drainage is high desirable (Jordahl, 2006). Additional treatment of flows from the drainage system may include diversion to evaporation ponds or ZLD (brine concentrator) system.

• Disposal. If the underlying aquifer is already of poor quality (i.e., >10,000 mg/L TDS), then substantial leaching of salts to groundwater may be permissible, and little advanced site design operations may be required.



FIGURE 2.13 IRRIGATION MANAGEMENT STRATEGIES USING CONCENTRATE

Leaching Capacity Plant irrigation, including irrigation of halophytes, typically requires some amount of irrigation above plant requirements in order to flush excess salts through the root zone. Leaching requirements vary with plant species, salinity of irrigation water, and climate. Without leaching, salts will accumulate in the plant root zone and eventually cause adverse effects to plant growth—even with halophytes. Leaching of salts into underlying groundwater may violate State water quality standards, especially where the groundwater aquifer is of higher quality than the water being land applied. Therefore, regulatory constraints may limit the feasibility of irrigating with brine concentrate.



Chemical Characteristics • Sodium Adsorption Ratio. When sodium concentration in the soil is high

relative to calcium and magnesium, destruction of soil structure and reduced soil permeability can result. The sodium hazard is evaluated by the sodium adsorption ratio (SAR), defined as:

Where Na, Ca and Mg concentrations are expressed in milliequivalents per liter (meq/L). SAR greater than 9 in irrigation water may adversely affect soil permeability (Ayers, 1985). The sodium hazard is usually not substantial when bulk salinity is high; however, if better quality water is received, through rainfall or alternative water sources, then sodium hazard may increase. Also, if alkalinity causes precipitation of calcium and magnesium carbonate in the soil, this would likewise increase the SAR, and potentially cause permeability problems.

• Specific Ion Toxicity. Sodium, chlorine and boron in irrigation water can cause toxic responses in sensitive plants. When plants are sprinkler irrigated, sodium and chloride can cause foliar damage, and a concentration of 3 meq/L for either sodium or chloride is typically used as a toxicity threshold. Boron concentrations above 0.7 mg/L may produce toxicity symptoms in sensitive plants, and leaching of boron is more difficult than leaching other salts. However, specific ion toxicity is very different for halophytes and therefore halophytes have a much higher toxicity threshold.

Land Requirements Land area required for brine irrigation depends on the volume of brine concentrate produced and plant water requirements. Evapotranspiration rate varies with climate (i.e., plants in hot, arid climates have higher transpiration rates than plants in cool, coastal areas). Table 2.12 shows differences in evaporation rates for various regions in the State. Land required for irrigation in a high ET region (Perris, California) and a relatively low ET region (Irvine, California) was determined, assuming irrigation of salt grass with 1 mgd of brine. Other assumptions included the following: • Soil: Irvine: Sorrento soils with 0.19 in/in of available water • Perris: Willows soils with 0.10 in/in of available water • No leaching fraction; irrigation at agronomic rate only • Reference ET and monthly precipitation from the California Irrigation Management

Information System (CIMIS) stations located in Irvine and at UC Riverside, respectively, for regional evaluation

• Sprinkler irrigation with 85 percent irrigation efficiency • Halophyte: Saltgrass, using crop coefficients previously determined for each month

of the year

2])[]([

][MgCa

NaSAR+

=



TABLE 2.12 AVERAGE SEASONAL AND ANNUAL CLASS-A PAN EVAPORATION

Station May-Oct

Nov-Apr Annual

Beginning of Record

Latest Data

in in in mo/yr mo\yr

Arvin-Edison WSD 66.2 21.3 87.5 Mar-67 Dec-77

Backus Ranch 85.6 30.5 116.1 Jun-36 Jun-62

Baldwin Park 40.9 18.5 59.5 Jul-32 Dec-53

Beaumont Pumping Plant 49.7 23.0 73.0 Jan-55 Sep-75

Casitas Dam 40.2 20.3 60.5 Sep-59 Sep-77

Castaic Dam Headquarters 51.8 29.0 81.0 Jun-68 Dec-78

Chula Vista 39.7 23.6 63.4 18-Sep Dec-79

Fullerton Airport 41.9 21.9 63.9 Jan-35 May-77

Henshaw Reservoir 49.4 18.5 67.9 Jul-59 Apr-79

Huntington Beach – Heil 39.6 18.1 57.6 Sep-34 Dec-45

Irvine Co Automatic 38.0 20.9 58.8 Feb-46 Jun-72

Lake Bard 49.0 33.0 82.0 Mar-67 Sep-77

Mockingbird Reservoir 34.3 20.8 55.0 Jul-41 Feb-79

Perris Reservoir Evaporation 60.4 27.0 87.4 Dec-63 Jan-79

Prado Dam 50.6 25.4 76.0 30-Jul Jan-69

Riverside Citrus Experimental Station 46.7 22.7 69.4 25-Jan Apr-78

San Bernardino Flood Control 52.2 23.8 76.0 Jun-59 Oct-73

San Jacinto Reservoir MWD 58.4 23.7 82.1 Jul-39 Sep-71

Silver Lake Reservoir 42.8 23.0 65.8 Jan-52 Dec-67

Tujunga Spreading Grounds – Evaporation 48.6 26.2 74.8 Dec-32 Dec-44

Vail Lake – USGS 54.6 25.9 80.5 Apr-52 Jun-76

Van Nuys Flood Control 15B 25.9 11.8 37.7 Jan-30 Jul-48

Notes: These values represent the sum of the monthly means.

Based on an average concentrate production of 1 mgd, approximately 553 acres of land would be required in Perris, and approximately 695 acres of land would be required in Irvine, California (Attachment A). Little to no irrigation of saltgrass would be required between November and March, when precipitation alone largely meets plant transpirational water demand. During the rainy season, rainfall would at least partially leach salts through the plant root zone, and this could potentially be supplemented with irrigation to achieve greater leaching. However, storage and/or alternative disposal options would need to be considered during those months.



Groundwater levels in Irvine may be relatively high, which would potentially present a problem with respect to salt migration into groundwater. Furthermore, while the calculated land requirement assumes no leaching fraction, in practice the absence of leaching would likely result in adverse salinity impacts to plants over time as excess salts accumulate in the root zone. The estimated acreages, however, are useful for comparing relative land requirements in areas with different climates.

Irrigation Costs Cost of brine irrigation of halophytes is highly specific to project location and depends on following:

• Volume and quality of concentrate • Distance to land application site • Irrigated acreage • Geographic location • Storage requirements • Land cost

For example, the capital and O&M costs for treating 1.0-mgd concentrate flow with a TDS range of 10,000 to 20,000 mg/L are $43,000,000 and $390,000 per year, respectively. This estimate is based on evaporation and rain fall data for Irvine, California.

2.6.2 Constructed Wetlands Constructed wetlands (CWs) use plants to biologically and chemically remove constituents from water and reduce micropollutant concentrations in the concentrate. Depending upon the application objective, the CWs can be configured as vertical flow, surface flow (SF), and submerged aquatic vegetation (SAV). An example of surface flow and submerged aquatic CW is presented in Figure 2.14.

Recent pilot testing conducted by the City of Oxnard (City of Oxnard, 2003; City of Oxnard, 2004; Jordahl, 2006) and a study by the WateReuse Foundation (Jordahl, 2006) indicate that brackish marshes can be constructed to significantly reduce the volume of concentrate through evapotranspiration. These studies also found that chemical constituents of concern in the membrane concentrate can be reduced to levels safe for biota in wetlands, thereby providing valuable habitat as an additional benefit.3

3 Testing was conducted on combined concentrate from the NF, RO, and EDR trains used at the Port Hueneme, California, desalination facility.



FIGURE 2.14 EXAMPLE OF SURFACE FLOW AND SUBMERGED AQUATIC CONSTRUCTED WETLANDS

For concentrate applications, a CW consists of high-salt-tolerant plant species that can be used to remove or concentrate constituents in the root zone of the plant or in sediments, allowing evapotranspiration to reduce the volume of flow while increasing the salinity of the concentrate stream. Halophytes are one type of plants that can be utilized in CWs for treating high TDS-containing RO concentrate (that is, TDS concentrations of more than 10,000 mg/L). Halophytes are distinguished by the ability of the plants to grow in a saline environment as either obligate or facultative. Obligatory halophytes are plants in need of salt, and facultative halophytes can live in saline and in freshwater conditions. Examples of halophyte systems include saline semi-deserts, mangrove swamps, marshes and sloughs, and seashores. Salt marsh grass (Spartina alterniflora) is an example of a halophyte and is shown in Figure 2.15. FIGURE 2.15 SALT MARSH GRASS GROWING NATURALLY



Advantages associated with constructed wetlands include:

• Uses a natural treatment process

• Creates aesthetic, educational, and recreational opportunities

• Provides habitat value

• Greatly reduces power needs compared to mechanical systems

• Has a proven record of treating municipal and industrial wastewater and stormwater runoff, including wastewater with high organic loading

• Provides specific constituent removal and polishes brine concentrate flows

Disadvantages associated with constructed wetlands include:

• Large footprint

• No full-scale project for brine concentrate treatment

• Potential exposure of wildlife to hazardous chemicals

• Potential impact to an underground source of drinking water (USDW) (if no liner used)

• Loss of potentially reusable product water through evapotranspiration

• Reduction of brine concentrate volume limited by the salt tolerance of NTS plant

Water quality and temperature strongly affect performance (both microbial uptake and evapotranspiration rates) of CWs.

Factors affecting the feasibility of implementing constructed wetlands for RO concentrate disposal include RO concentrate quality and flow rate, geographical location, hydrology, water balance, and site location. Many times, a volume-reduction technology would be necessary to reduce the RO concentrate volume if constructed wetlands were implemented. Wetlands are ecological systems; therefore, water quality has a strong impact on the type of microorganism that dominates. In addition, the TDS content of the water will determine the suitability of plants for wetland application.

Capital and O&M costs for an NTS were based on the assumption that the NTS is modeled after the sequence of wetlands being tested by the City of Oxnard Water Division for treatment of brine concentrate, as described on the City of Oxnard Web site (www.oxnardwater.org/ great/wetlands.asp) and as described in Draft Results for the City of Oxnard GREAT Program Membrane Concentrate Pilot Wetland Project (City of Oxnard, 2004). However, this testing was performed using concentrate from a groundwater RO facility.



Table 2.13 provides an example of an estimated volume reduction of 50 percent provided under an NTS sequence during the summer for a 1-mgd brine concentrate feed flow. The system area is estimated to be 68 acres (32 acres of wetlands plus 36 acres of winter pond storage) for 1 mgd of brine concentrate flow. Capital costs for an NTS capable of handling a 1-mgd flow is $9,600,000.

TABLE 2.13 EXAMPLE OF VOLUME REDUCTION FOR NTS SYSTEM DURING SUMMER

Type of NTS

Fractional Area (%)

Area (acres)

Inflow (mgd)

ETa rate (cm/d)

Outflow (mgd)

Volume Reduction

(%)

VF 15 5 1.00 0.75 0.97 4

SF 36 12 0.97 1.58 0.77 21

SAV 49 16 0.77 1.15 0.57 26

Total 100 32 - - - 50

Note: a Estimated rate of ET in Oxnard, Ventura County cm/d centimeters per day VF peat-based vertical flow SF surface flow SAV submerged aquatic vegetation

O&M activities will consist of the following periodic activities:

• Weekly inlet and control structure and flow inspection • Monthly water quality monitoring • Periodic vector management • Annual vegetation management

The annual O&M cost of an NTS that treats a flow of 1 mgd is approximately $286,500. The unit treatment cost is $0.40 per 1,000 gallons of concentrate, which is near the upper range of operational costs described by Kadlec and Knight (Kadlec, 1996) and compares favorably with a unit cost of $0.43 per 1,000 gallons of treated capacity for the Laguna Niguel Wetland Capture and Treatment Network (City of Laguna Niguel Public Works Department, 2004).

Environmental Concerns Species protection is a large concern driving regulation of solids residual-producing processes using NTSs. Large wetland ponds are attractive to many birds that frequent water. In some cases, high concentrations of metals and other constituents in the ponds have caused birth defects in waterfowl inhabiting ponds. Control of waterfowl can be handled using several different methods. One technique is to fire cannons periodically, creating a loud noise to scare waterfowl away from the evaporation ponds. However, the sound from the cannons generally carries a long distance and can be a nuisance to neighboring residential areas. Another technique is to broadcast the sound of natural predators over a loudspeaker system. This type of control is in use at fruit orchards across the country and has been proven to be quite



effective. The sound emitted from these systems does not carry as far as the cannons, minimizing the potential for public complaints; however, birds frequently become immune to these methods. In addition, these methods do not protect reptiles, amphibians, or small mammals that enter ponds even when ponds have fences.

In addition, natural treatment systems must be lined to prevent seepage into the groundwater; otherwise, ponds would be considered a Class V injection well. Permitting of a Class V injection well, which can be extremely difficult, will be discussed in the deep well injection section of this report. Given proper lining, permitting an evaporation pond is a relatively simple process involving specific state and local regulations. If misting equipment is included to reduce the required area of the ponds, regulatory approval could be slightly more.

2.7 Two-Pass Nanofiltration

The Long Beach Water Department (LBWD) has developed and patented a two-pass NF process to produce drinking water from seawater. The two-pass, multistage nanofiltration membrane process treats water at a lower operating pressure and energy than a conventional single-pass seawater reverse osmosis (SWRO) desalination process. SWRO processes typically use thin-film composite membranes. A key component of the two-pass NF is the second-pass concentrate recycle loop, which dilutes feedwater and makes NF membranes feasible. The first pass removes approximately 90 percent of salinity, and the second pass removes 93 percent resulting in a total salt rejection of approximately 99 percent. The LBWD pilot unit is shown in Figure 2.16. FIGURE 2.16 LBWD TWO-PASS NF PILOT PROJECT



The presence of two-passes of the NF increases reliability. In addition, the second pass can be operated at a higher pH by chemical addition to improve boron rejection. The overall recovery from the process is approximately 30 to 45 percent, which is lower than conventional RO desalination. Although two-pass NF was developed in late 2001, no full-scale application of this process exists. This could be due to concerns over lower water recoveries. No capital and O&M costs information is available for this technology because a full-scale application has not been implemented.

Advantages associated with two-pass NF include:

• Application to brine concentrate flows high in silica content with pH adjustment

• Small site footprint

• Lower energy cost

Disadvantages associated with two-pass NF include:

• Lower water recoveries than conventional RO

• No experience, requires detailed pilot testing to demonstrate performance and optimize operating conditions

• Complex, requires highly skilled operation

2.8 Forward Osmosis

Forward osmosis (FO) is an osmotic process that uses a semi-permeable membrane to separate salts from water. FO uses an osmotic pressure gradient instead of hydraulic pressure, which is used in RO, to create the driving force for water transport through the membrane. Figure 2.17 illustrates the FO process. FIGURE 2.17 SCHEMATIC ILLUSTRATION OF RO AND FO



The concentrated solution, or draw solution on the permeate side of the membrane, is the source of the driving force in the FO process. Osmotic driving forces in FO can be significantly greater than hydraulic driving forces in RO. This results in the potential for higher water flux rates and recoveries. The selection of an appropriate draw solution is the key to FO performance. The draw solution should:

• Have a high osmotic efficiency(that is, have a high solubility in water and have a low molecular weight)

• Be non-toxic; trace amounts of chemicals in product water might be acceptable

• Have chemical compatibility with the membranes

When potable water production is considered via FO, the draw solute should be separated from water easily and economically. Example draw solutions include magnesium chloride, calcium chloride, sodium chloride, potassium chloride, ammonium carbonate and sucrose. A simplified process schematic of an FO process is presented in Figure 2.18.

There are two major limitations of using FO:

• High-performance membranes do not exist for FO process • A draw solution that is easily separable has not been identified FIGURE 2.18 SIMPLIFIED PROCESS SCHEMATIC OF FORWARD OSMOSIS

Existing commercially available RO membranes are not suitable for FO because such membranes have a relatively low product water flux, which can be attributed to severe internal concentration polarization in the porous support and fabric layers of RO membranes. For this reason, existing membranes cannot support the flux required in FO.



FO is promising, but the process is still under development. A bench-scale FO unit was built and has been operated at Yale University laboratory since 2005; the unit is shown in Figure 2.19. However, FO cannot be used in large-scale applications until a membrane is developed that has high salt rejection and low internal concentration polarization. Since this technology is in the developmental stage, information regarding its advantages, disadvantages, and cost is not available. FIGURE 2.19 BENCH-SCALE FORWARD OSMOSIS UNIT AT YALE UNIVERSITY

Source: Elimelech Lab, 2009

2.9 Membrane Distillation

Membrane distillation (MD) combines membrane technology and evaporation processing in a single unit. MD transports water vapor through the pores of hydrophobic membranes using the temperature difference across the membrane. The membrane allows water vapor to penetrate the hydrophobic surface while repelling the liquid. The clean vapor is carried away from the membrane and condensed as pure water, either within the membrane package or in a separate condenser system.



MD differs from other membrane technologies because the driving force that pushes the water through the membrane is not feed pressure but temperature. In MD units, vapor production is enhanced by heating the feedwater, which increases the vapor pressure and penetration rate. MD requires the same amount of energy input to heat and condense vapor as traditional evaporation; however, it does not require boiling water and is operated at ambient pressure. The energy requirement for MD is lower than conventional evaporation requires. MD is most efficient on low-grade or waste heat, such as industrial heat streams or even solar energy (Scott, 2007). Also, efficiency of the unit can be improved with heat recovery.

MD membranes must be microporous (pore diameters of 0.05 to 0.2 micrometer [μm]) and nonwettable by the feed. For MD applications, hydrophobic polypropylene (PP), polytetrafluoroethylene (PTFE), and polyvinylidene fluoride (PVF) membranes can be used either as flat sheets, or as hollow fibers. Thermal and chemical resistance, narrow pore-size distribution, high porosity, and low thermal conductivity are other desirable membrane qualities. Membrane modules have been developed in various configurations, including plate-and-frame, spiral-wound and hollow-fiber (Scott, 2007) for MD applications.

A variety of arrangements and configurations can be used to induce the vapor through the membrane and to condense penetrant gas; however, the feedwater must always be in direct contact with the membrane. Condensation is typically achieved via four process configurations (Daniel, 2004), which are:

• Direct-Contact Membrane Distillation: The cool condensing solution directly contacts the membrane and flows countercurrent to the raw water. This is the simplest configuration and is best suited for applications such as desalination and concentration of aqueous solutions (for example, juice concentrates).

• Air-Gap Membrane Distillation: An air gap followed by a cool surface. The use of an air gap configuration allows larger temperature differences to be applied across the membrane, which can compensate in part for the greater transfer resistances. The air gap configuration is the most general and can be used for any application, including desalination.

• Sweep-Gas Membrane Distillation: A sweep gas pulls the water vapor and/or volatiles out of the system. This is useful when volatiles are being removed from an aqueous solution.

• Vacuum Membrane Distillation: A vacuum is used to pull the water vapor out of the system. This is useful when volatiles are being removed from an aqueous solution.

A schematic illustration of an air gap MD is shown in Figure 2.20.



FIGURE 2.20 SCHEMATIC OF AIR GAP MD AND AIR GAP MD WITH HEAT RECOVERY

Thermal efficiency of MD declines with salinity because highly saline water requires a greater temperature drop across the air gap, leading to greater losses of heat conduction through the air gap. Similarly, as salinity is increased, lower fluxes can be achieved due to reduced head transfer with highly saline water. The thermal efficiency and operating flux is estimated as a function of water salinity (Daniel, 2004). These relationships are presented in Figure 2.21, where the salinity has a molality (m) unit and 1 molal saline solution is equal to salt concentration of approximately 62,000 mg/L. FIGURE 2.21 THERMAL EFFICIENCY AND FLUX AS FUNCTION OF SALINITY



A pilot test of MD using RO concentrate generated from a groundwater desalination facility operated by Eastern Municipal Water District (EMWD) was performed. The pilot test study showed that the operating flux was between 1.2 and 2.4 gallons per square foot per day (gfd) at feed and permeate temperatures of 40 and 20 degrees Celsius (°C), respectively. Increasing feed temperature to 60°C increased flux to 6.0 gfd. The water recoveries were between 60 and 81 percent, with an average of 70 percent during pilot testing. The pilot MD exhibited excellent salt rejections (that is, 99 percent or greater) during pilot testing. Potential advantages of MD include:

• High-quality water (distillate) is produced; however, distillate quality is dependent upon the extent of wetting of the membrane.

• MD is applicable for brine concentrate flows that are high in silica content.

• Low-grade energy and waste heat can be used.

• Little or no pretreatment may be required.

• MD requires relatively simple operation compared to other thermal processes.

Disadvantages associated with MD include:

• The process is still under development; no-full-scale performance data are available.

• MD has relatively low recoveries and fluxes, based on EMWD pilot test results.

• The amount of energy required is high for a relatively low flux and recovery operation.

• High salinity limits mass transfer, which reduces flux through the system.

• Maintaining hydrophobic characteristics of membrane could be a challenge.

• No commercial membranes are available for MD applications. Membranes that are used in pilot and bench-scale MD demonstrations use microfiltration (MF) membranes that have a specific pore size and are made of hydrophobic materials.

MD is a technology still being developed. One key to the success of this technology will be the development of microporous membranes that have the desired porosity, hydrophobicity, low thermal conductivity, and a low potential for fouling. Development of these membranes would make MD an attractive and cost-effective technology in the future. There are no capital and O&M cost data available for this technology because it is still in the developmental stage.



2.10 Slurry Precipitation and Reverse Osmosis (SPARRO)

The major obstacle to operating an RO process at higher recoveries is the precipitation of sparingly soluble inorganic salts, most notably calcium sulfate (CaSO4). Inorganic salt precipitation can be controlled at lower recoveries by using an appropriate antiscalant (AS) and by controlling feedwater pH. At higher recoveries (greater than 95 percent, as would be needed for large-scale RO), antiscalants are not effective, and pH control does not prevent precipitation of some problematic minerals such as barium sulfate and calcium sulfate, which cannot be removed by chemical cleaning. Slurry Precipitation and Reverse Osmosis (SPARRO) involves circulating a slurry of seed crystals within the RO system, which serve as preferential growth sites for calcium sulfate and other calcium salts and silicates. These seed crystals enable precipitate to begin as their solubility products are exceeded during the concentration process within the membrane tubes (GJG, 2000). The preferential growth of scale on the seed crystals prevents scale formation on the membrane surface. This process is confined to the use of membrane configurations that will not plug, such as tubular membrane systems, due to the need to circulate the slurry within the membranes. A conceptual schematic of SPARRO is presented in Figure 2.22.

FIGURE 2.22 CONCEPTUAL ILLUSTRATION OF SPARRO



In the SPARRO system, the water to be desalted is mixed with a stream of recycled concentrate containing the seed crystals and then fed to the RO process. The concentrate with seed crystals is processed in a cyclone separator to separate the crystals so that the desired concentration is maintained. This concentration is maintained in a reactor tank by controlling the rate of wasting the upflow and/or underflow streams from the separator. This technology has been tested for treating scale in a mine water (GJG, 2000), as well as on primary and secondary brine from the EMWD zero liquid discharge (ZLD) pilot project. The combined recovery of the process was greater than 90 percent (GJG, 2000). Although final pilot testing data have not been published, preliminary results from the EMWD study indicate that more than 80 percent recovery is achievable using the SPARRO process.

Potential advantages of SPARRO include:

• Low energy input compared to thermal processes.

• Less pretreatment needs than other hybrid technologies.

Disadvantages associated with SPARRO include:

• The process is still under development.

• SPARRO lacks full-scale performance, capital cost, and O&M data.

• Process has low rejection of salt (that is, 80 to 85 percent) compared to other RO-type processes (greater than 95 percent).

• Large footprint is necessary due to use of tubular membranes and large reaction tank required.

• Relatively complex operation is required.

Although the SPARRO process is not new, it is still under development as a brine-concentrate management technology. This technology has relatively low energy costs but requires a large footprint to house the tubular RO membranes and requires the recovery and reuse of precipitated salts. No capital or O&M cost data are available for this technology.

2.11 Advanced Reject Recovery of Water

Advanced Reject Recovery of Water (ARROW) is a high-recovery, advanced membrane system that couples softening process with RO to increase water recovery. This is a proprietary technology marketed by Advanced Water Solutions and O’Brien & Gere. In RO and other desalination processes such as EDR, water recovery is limited by the concentration of scale precursors as well as by the concentration of colloidal and fouling material in the water. These compounds settle on the membrane surface or plates and reduce productivity. A common pretreatment to minimize scale fouling includes acidification of the feedwater and addition of an antiscalant. While calcium and magnesium hardness can be addressed by acidifying



the feedwater, acidification is ineffective for reducing sulfate hardness. Silica also has a limited solubility, and acid addition further reduces solubility of silica. Increasing pH can push the solubility limit of silica, but it could result in deposition of calcium carbonate on the RO membrane surface or EDR plates. ARROW has a number of configurations that can be adjusted depending on flow rate, hardness, concentration of silica relative to other hardness precursors, and TDS concentration. The ARROW process is illustrated in Figure 2.23 and includes the following steps:

1. Pretreatment: Dual media or membrane filtration is used to minimize colloidal fouling. A silt density of less than 4 is targeted. Also, pretreatment includes the addition of acid (if necessary) and antiscalant.

2. First-Stage RO: ARROW produces a permeate stream of 60 to 75 percent of the flow, while 40 to 25 percent of the stream is RO concentrate.

3. Second-Stage RO: Concentrate from the first-stage RO is treated and combined with an appropriate flow of recycled stream from second-stage RO concentrate.

4. Softening of RO Concentrate Stream from Second-Stage RO: ARROW uses either chemical precipitation to reduce calcium, magnesium, and silica hardness or IX softening containing strongly acidic cation exchange resins, if silica hardness is not a concern. Chemical precipitation uses caustic soda or soda ash depending upon the ratio of alkalinity to calcium hardness.

5. Recovery: A small amount of flow from second–stage RO concentrate and a small reject stream either from the bottom of the clarifier or from the IX system is sent to a solar evaporator or thermal crystallizer. The combined volume of two reject streams is less than 5 percent giving an overall process recovery of greater than 95 percent.

FIGURE 2.23 PROCESS FLOW SCHEMATIC OF ARROW



To date, ARROW has only one full-scale application in the industrial water treatment field. This project is a 33-gpm unit in New Jersey, as pictured in Figure 2.24. Because the technology is very new, no capital and O&M cost data are available. However, the cost is expected to be similar to the EMS and PS/RO systems because the unit uses similar principles to increase RO recovery. FIGURE 2.24 NEW JERSEY ARROW PROJECT FOR REJECT RECOVERY

Potential advantages of the ARROW system include:

• High-quality product water

• Applicable for brine concentrate flows that are high in silica content

• High water recovery (that is, 95 percent), which minimizes RO concentrate generation and disposal costs

• Compact skid-mounted system, which reduces not only footprint requirements but also equipment delivery and installation time (appropriate for applications of less than 0.25 mgd)

Potential disadvantages associated with ARROW include:

• Process is still under development; no full-scale applications exist in municipal water or wastewater treatment.

• High cost of chemicals used for pretreatment and softening of water.

• Combining the RO reject and IX regenerate would cause a precipitate to form that could reduce the crystallizer design or on-line factor.

• ARROW is a complex operation that requires skilled operators.

• Pilot testing is required to determine key design criteria.



• Sludge from precipitative softening might require separate disposal, which creates additional challenge and expense.

• Existing skid-mounted units are applicable only to very small systems (that is, systems up to 0.25 mgd). For larger systems, custom design, which increases construction time significantly, is required to reduce the capital cost.

2.12 Capacitive Deionization

Capacitive Deionization (CDI) is a low-pressure, non-membrane desalination technology that uses basic electrochemical principles to remove dissolved ions from solution. This process was developed and patented at Lawrence Livermore National Laboratory (Joseph, 1996). Aqueous solution of soluble salts are passed through pairs of porous, highly specific surface area (400 to 1,100 square meters per gram [m2/g]) with very low electrical resistivity (less than 40 kilohm-meters) carbon aerogel electrodes that are held at a potential difference of 1.2 volts (V). Eventually, the electrodes become saturated with ions and must be regenerated. Using CDI, once the applied potential is removed, the ions attached to the electrodes are released and flushed from the system. This flushing produces a more concentrated brine stream, as illustrated in Figure 2.25.

FIGURE 2.25 CDI OPERATION (TOP) AND REGENERATION (BOTTOM)



CDI and EDR use similar electrochemical principles to remove ions from aqueous solutions. The difference between CDI and EDR is that CDI uses the reversible electrostatic adsorption in the electrical double layer close to the surface of the polarizable electrode, while EDR employs electrolysis on the surface of a nonpolarizable membrane. Surface adsorption requires much less energy than electrodialysis.

Although the power efficiency of CDI is nearly an order-of-magnitude better than RO and mechanical and thermal evaporative processes, it is plagued by a low ratio of water recovery (that is, 70 percent) with brackish water desalination. In addition, gel electrodes used in CDI are expensive. Also, the surface area of the electrodes is small, which reduces the salt capacity of the electrode and increases the number of electrodes required. TDA Research has developed a route to monolithic carbon electrodes with a combination of large (mesopores) and small pores (micropores), which are much less expensive than carbon aerogel electrodes. The benefit of the mesopores is that they allow the liquid to penetrate the carbon for easy access to the high-surface-area micropores while increasing capacity of salt uptake. Researchers at Massachusetts Institute of Technology (MIT) have proposed a CDI process with permeating flow discharge (PFD). In this modified approach, the brackish water is permeated through the porous electrodes rather than flowing between the electrodes, as is the case in the conventional axial flow discharge (AFD) process. This reduces discharge time and translates to an increase in water-recovery ratio by approximately 30 percent. However, increased recovery might not be applicable to brine-concentrate treatment because the MIT study used very low feedwater TDS values (600 to 990 mg/L).

Potential advantages of CDI include:

• CDI has low consumption of energy.

• No chemicals are used for regeneration of electrodes.

• Silica does not limit the recovery.

Potential disadvantages of CDI include:

• CDI is still under development.

• CDI lacks full-scale performance, capital, and O&M data.

• The process cannot remove all constituents (that is, boron, silica, and uncharged micropollutants).

• CDHS does not recognize CDI as a water treatment technology because CDI does not provide a barrier against pathogens.

• Multiple stages might be required for treatment of high-TDS feedwater, such as brine-concentrate, which increases capital and O&M costs.

• CDI recovers lower amounts of water than conventional membrane processes.


3 Zero Liquid Discharge Zero Liquid Discharge refers to processes that fully removes water from the concentrate stream (in other words, no liquid is left in the discharge). The end product of a ZLD system is a solid residue of precipitate salts that needs to be transferred to an appropriate solid waste disposal facility, such as a landfill. Toxicity tests and other applicable tests will determine the type of the landfill (municipal solids waste landfill versus hazardous waste landfill) that can handle the ultimate disposal of the solid residue. ZLD systems range from less complex/technological (that is, natural treatment systems) to highly complex/technological (that is, complex mechanical processes) solutions.

ZLD systems include:

• Combination Thermal Process with Zero Liquid Discharge • Mechanical and Thermal Evaporation ZLD • Enhanced Membrane and Thermal ZLD • Evaporation Ponds • Wind-Aided Intensified Evaporation (WAIV) • Dewvaporation • Salt Solidification and Sequestration

Technologies used in conventional ZLD systems include the use of evaporators and brine crystallizers to completely separate dissolved salts from the water. These technologies are relatively complex and energy intensive. Several ZLD technologies have been successfully implemented for industrial water treatment; however, the ZLD concept is new when applied to treatment and disposal of concentrate from large-scale RO systems. WAIV, Dewvaporation, and Salt Solidification and Sequestration are developmental ZLD technologies.

Permit requirements are minimal for operation of solids residual-producing process equipment for membrane concentrate disposal and are similar to requirements for implementing wastewater treatment processes. However, some public health and ecosystem health concerns exist for regulations governing brine concentrate management using solids residual producing processes. Public health concerns include protection of groundwater and other potable water supply sources. Ecosystem health concerns include protection of wildlife from constituents of concern at evaporation ponds.



3.1 Combination Thermal Process with Zero Liquid Discharge

Combination thermal process ZLD systems combine mechanical or thermal evaporation for volume reduction with crystallization to produce a dry waste. Figure 3.1 presents a schematic of a combination thermal ZLD process. This section will describe the different components of a combination thermal ZLD system. FIGURE 3.1 COMBINATION THERMAL PROCESS WITH ZERO LIQUID DISCHARGE SYSTEM SCHEMATIC

3.1.1 Mechanical and Thermal Evaporation MTE portion of Combination Thermal Process ZLD was covered in Section 2.5.

3.1.2 Crystallizer Crystallization is a mechanical evaporation process that uses heat to transform the concentrate waste slurry from the evaporator into purified distillate and a solid product. Crystallizer feed is typically a concentrate stream, which has undergone volume reduction and has a Total Solids (TS) concentration of about 200,000 to 300,000 mg/L. Figure 3.2 displays the process flow diagram for a typical forced circulation crystallizer (FCC).

MMeecchhaanniiccaall EEvvaappoorraattiioonn

CCrryyssttaalllliizzeerr

BB//CC

PPrroodduucctt WWaatteerr

DDrryy WWaassttee



FIGURE 3.2 FORCED CIRCULATION CRYSTALLIZER PROCESS FLOW DIAGRAM

ProductWater

Salt

BrineConcentrate

Vapor

Liquor

1

2

3

4 5

Note: Numbers correspond with descriptions in text.

The following steps correspond to the numbers in the figure and describe the process flow steps.

1. The 20 to 30 percent concentrate is recirculated through a heat exchanger, where compressed and desuperheated steam heats the brine above its boiling point at atmospheric pressure as the steam condenses on the outsides of the tubes.

2. The heated concentrate then enters a separator chamber (vapor body or flash tank), operating at a slightly lower pressure, resulting in flash evaporation of water, and formation of insoluble salt crystals in the concentrate.

3. The vapor passes through mist eliminators and enters the vapor compressor, which heats the vapor. Compressed vapor is desuperheated with hot distillate and flows to the outside of the heat-transfer tubes, heating the recirculated concentrate that flows inside the heat-transfer tubes. Mechanical compressors are used in most wastewater crystallizer applications. The mechanical vapor compressor is responsible for about 80 percent of the ~250-kWh energy usage per 1,000 gallons of FCC feed.

4. From 1 to 5 percent of the concentrate/crystal liquor is wasted to separate the insoluble salt from the liquor. Typically, salt crystals are separated from the liquor with a centrifuge or filter press. Salt can be disposed of in a landfill, and concentrate or filtrate can be returned to the FCC feed tank.

5. Total recovery of product water across the crystallizer is between 95 and 99 percent. The condensate can be delivered as distillate water, make-up water, or a blend with RO product water.



FCCs are used directly with high recovery RO reject or in combination with brine concentrators to create a dry salt waste and a high-quality product water. Crystallizers are a proven technology for commercial production of salt. They have more recently been applied to mixed salt waste streams from RO and mechanical evaporation systems and in this application, have a small site footprint. However, crystallizers are mechanically complex and have high capital and O&M costs (primarily energy costs). In addition, crystallizers could pose aesthetic issues associated with the vertical profile, although they are shorter than vertical tube, falling film evaporators.

Advantages associated with FCCs include:

• Proven history of use in industrial applications • High-quality product water • Small site footprint when used for waste stream applications

Disadvantages associated with FCCs include:

• High capital and O&M costs (primarily energy costs) • May require frequent cleaning when used for complex salt waste streams. • Mechanically complex • Potential aesthetic issues associated with vertical profile

Estimated capital costs for an FCC unit are summarized in Table 3.1. Capital cost estimates are based on vendor data for the FCC produced by GE-Ionics. Capital costs for a 1-mgd FCC unit are approximately $17.7 million.

TABLE 3.1 FCC CAPITAL COST MATRIX

0.2 mgd 1.0 mgd 5.0 mgd

Total Capital Cost Including Equipment Installation , $ $6,170,000 $20,681,000 $59,826,000

Note: Capital costs for 0.2-mgd system is according to BBARWA, 2006. Cost for other flow rates were estimated using the following formula: Cost 2=(Flow 2/Flow 1)^0.66*Cost 1. (Flow 1 is 0.2 mgd).

Table 3.2 provides O&M cost estimates for FCC. O&M costs include power, labor, chemicals, maintenance and replacement costs for key equipment components (i.e., vapor compressor). These estimates were provided by GE-Ionics and are based on a 1-mgd feed flow.



TABLE 3.2 FCC OPERATION AND MAINTENANCE COSTS


Power $4,844,000

Parts $1,035,000

Chemicals $282,000


Labor $225,000


3.1.3 Combination Thermal Process ZLD Systems The most common ZLD setup is a vertical-tube falling-film with vapor compression evaporation followed by an FCC. The salt waste or dry concentrate from the process is ultimately transferred to a landfill for final disposal. Advantages and disadvantages of combined thermal ZLD systems are similar to those discussed for mechanical evaporation and crystallizers. Combined thermal ZLD systems can handle a wide range of feedwater compositions while producing high-quality product water. Combined thermal ZLD systems commonly have been used in industrial applications. Major disadvantages of these systems are high capital and O&M costs, the mechanical complexity associated with the combined systems, and the need for more frequent cleaning of the FCC unit. The high O&M costs are driven by the amount of energy required to run a combined thermal ZLD system. Other disadvantages include the height of the separator chamber (flash tank or vapor body) profile, which might be limited by local regulations or aesthetics.

Capital costs for combined thermal ZLD were provided by Ionics and are tabulated in Table 3.3. Capital costs for a combined thermal ZLD unit are approximately $21 million. This cost is based on a system with a 1-mgd evaporator and a 0.05-mgd crystallizer.

TABLE 3.3 CONVENTIONAL ZLD CAPITAL COST

Cost

MTE Capital Cost (1 mgd), $ 17,698,000

FCC Capital Cost (0.05 mgd), $ 2,864,000

Total Capital Cost for Conventional ZLD, $ 20,562,000



O&M costs for combination thermal process ZLD are high due the energy usage of the systems components. Table 3.4 summarizes the O&M costs for a combined thermal ZLD facility with 1-mgd of feedwater flow to the evaporator and 0.05-mgd flow of concentrate slurry to crystallizer. The projected annual O&M costs are approximately $6.3 million and are predominantly energy costs.

TABLE 3.4 FCC OPERATION AND MAINTENANCE COSTS

Component MTE O&M Cost, $/year FCC O&M Cost, $/year Conventional ZLD

O&M Cost, $/year

Power $4,000,000 $243,000 $4,243,000

Parts $885,000 $144,000 $1,029,000

Chemicals $250,000 $15,000 $265,000

Maintenance $531,000 $86,000 $617,000

Labor $180,000 $180,000

Total O&M Cost, $/year $5,846,000 $488,000 $6,334,000

3.2 Enhanced Membrane and Thermal System ZLD

The Enhanced Membrane and Thermal System ZLD system combines EMS with thermal-driven crystallization to produce a dry waste. The EMS utilizes IX softening of membrane reject to prevent scaling and operates a three-stage RO system at a high pH to reduce the amount of concentrate produced. Following the EMS process, a thermal-driven crystallizer is used to produce a dry waste for disposal.

Advantages and disadvantages of the Enhanced Membrane and Thermal System ZLD are similar to EMS and crystallizers. This type of ZLD system is a proven technology for industrial brine concentrate management high in silica that requires high-quality product water. However, this system is complex to operate and has high capital and O&M costs. In addition, this technology may require a precipitative process to be used in place of IX for some waters.

Cost data are not available. However, the capital costs are expected to be similar to the combined thermal ZLD.

3.3 Evaporation Ponds

Evaporation ponds rely on solar energy to evaporate water from the concentrate, leaving behind precipitated salts, which are periodically collected and disposed of in landfills. Evaporation ponds are most efficient in arid and semi-arid climates where high net evaporation rates are the norm. Evaporation rates can be enhanced by providing a larger evaporative surface. One option is to include mechanical misting



equipment that sprays the concentrate into the air in tiny droplets. However, misting is controversial because fine mist and dry salt particles can leave the site as drift, creating a secondary nuisance.

Evaporation ponds rely on solar energy to evaporate water from the membrane concentrate stream, leaving behind precipitated salts, which ultimately are disposed of in a landfill. Evaporation ponds are optimal in arid climates with high net evaporation rates, which decreases the pond area required, compared to humid climates with low net evaporation rates. The practicality of evaporation ponds is not limited by concentrate quality.

In the most common case, concentrate is conveyed to evaporation ponds where it is spread over a large area and allowed to evaporate. Multiple ponds are constructed to allow continued receipt of concentrate when a pond is taken offline for periodic maintenance. Periodic maintenance includes allowing the evaporation pond to be idle to desiccate the precipitated salts. When the precipitated salts have reached a satisfactory consistency, the precipitated salts are removed from the ponds and transported to a landfill for ultimate disposal.

The evaporation ponds must be lined appropriately to prevent percolation of reject water into the groundwater table, which could affect a USDW. The material and thickness of the liner must be selected appropriately because increased salt content could cause the liners to deteriorate.

Factors affecting the feasibility of implementing evaporation ponds for disposal of RO concentrate include the flow rate of the RO concentrate, and the geographical location and specific site location of a prospective evaporation pond. The flow rate of the RO concentrate is the primary factor affecting the area required for the evaporation ponds. The greater the flow rate of RO concentrates, the larger the area required for evaporation ponds. An estimate of the pond area required should take into account the reduced evaporation rate of a brine solution compared to typical lower-TDS water and the lower “lake” evaporation rate compared to the “pan” evaporation rate. A general guideline is to apply a factor of 0.7 to the pan evaporation rates shown in Table 3.5.

For example, an evaporation pond for 1 mgd of concentrate flow with a TDS concentration of 8,000 mg/L constructed at a site with a net evaporation rate of 90 inches per year is about 220 acres. The actual pond area constructed should be greater than the 220 acre minimum pond area required to allow for standby area that would be put into service when other ponds are being cleaned and to accommodate reduced evaporation as salinity increases. As a general guideline, an allowance of 20 percent should be added for construction of dikes to contain the brine concentrate and service roads.



TABLE 3.5 AVERAGE SEASONAL AND ANNUAL CLASS-A PAN EVAPORATION

Station May-Oct

Nov-Apr Annual

Beginning of Record

Latest Data

in in in mo/yr mo/yr

Arvin-Edison Water Storage District 66.2 21.3 87.5 Mar-67 Dec-77

Backus Ranch 85.6 30.5 116.1 Jun-36 Jun-62

Baldwin Park 40.9 18.5 59.5 Jul-32 Dec-53

Beaumont Pumping Plant 49.7 23.0 73.0 Jan-55 Sep-75

Casitas Dam 40.2 20.3 60.5 Sep-59 Sep-77

Castaic Dam Headquarters 51.8 29.0 81.0 Jun-68 Dec-78

Chula Vista 39.7 23.6 63.4 18-Sep Dec-79

Fullerton Airport 41.9 21.9 63.9 Jan-35 May-77

Henshaw Reservoir 49.4 18.5 67.9 Jul-59 Apr-79

Huntington Beach – Heil 39.6 18.1 57.6 Sep-34 Dec-45

Irvine Co Automatic 38.0 20.9 58.8 Feb-46 Jun-72

Lake Bard 49.0 33.0 82.0 Mar-67 Sep-77

Mockingbird Reservoir 34.3 20.8 55.0 Jul-41 Feb-79

Perris Reservoir Evaporation 60.4 27.0 87.4 Dec-63 Jan-79

Prado Dam 50.6 25.4 76.0 30-Jul Jan-69

Riverside Citrus Experimental Station 46.7 22.7 69.4 25-Jan Apr-78

San Bernardino Flood Control 52.2 23.8 76.0 Jun-59 Oct-73

San Jacinto Reservoir Municipal Water District 58.4 23.7 82.1 Jul-39 Sep-71

Silver Lake Reservoir 42.8 23.0 65.8 Jan-52 Dec-67

Tujunga Spreading Grounds – Evaporation 48.6 26.2 74.8 Dec-32 Dec-44

Vail Lake – United States Geographical Survey 54.6 25.9 80.5 Apr-52 Jun-76

Van Nuys Flood Control 15B 25.9 11.8 37.7 Jan-30 Jul-48

Notes: These values represent the sum of the monthly means.



Advantages associated with evaporation ponds include:

• Proven in industrial and wastewater applications

• Simple, low-technology solution

• Insensitive to energy costs (not withstanding cost of conveyance to ponds)

Disadvantages associated with evaporation ponds include:

• Implementation of evaporation ponds is sensitive to land costs.

• Liners are required to prevent seepage.

• Evaporation ponds are sensitive to climate (that is, they are most effective in arid climates with high evaporation rates).

• Potential regulatory and environmental/habitat issues exist due to accumulation and concentration of micropollutants

• Residuals have to be disposed of in landfills during periodic maintenance

Evaporation ponds must be lined to prevent seepage into the groundwater, or the ponds would be considered a Class V injection well; permitting an evaporation pond as a Class V injection well would be extremely difficult. To permit a Class V injection well, the project proponent has to show that all constituents in the water are at lower concentrations than those found in the native groundwater. However, installing a double liner with leachate collection system should remove the Class V requirements.

Another major concern with installation of evaporation ponds is the control of habitat, including that for waterfowl. Large evaporation ponds are attractive to many birds. In some cases, high concentrations of selenium in evaporation ponds have caused birth defects in waterfowl; however, waterfowl control can be successfully accomplished by broadcasting the sound of the natural predators of the fowl over a loud-speaker system. This type of control is in use at fruit orchards across the country and has been proven to be quite effective.

Evaporation pond costs are highly specific to project location and depend on:

• Concentrate volume • Geographic location (i.e., evaporation rates and rain falls) • Storage requirements • Land cost

For example, the capital and O&M costs for treating 1.0-mgd concentrate flow via an evaporation pond are approximately $43,000,000 and $390,000 per year, respectively. This estimate is based on evaporation and rainfall data for Irvine, California. This estimate does not include land acquisition.



3.3.1 Enhanced Evaporation Evaporation can be enhanced by using mechanical misting equipment, which decreases the required pond surface area by increasing the evaporation rate. Mechanical misting equipment (for example, the Slimline Evaporator, also known as the Turbo-Mist Evaporator) works by spraying the brine concentrate into the atmosphere in tiny droplets, thereby increasing the liquid surface area and substantially increasing the rate of evaporation. Depending on the atmospheric conditions, large amounts of water can be evaporated leaving only precipitated salts. A photograph of an evaporation pond utilizing misting equipment is shown in Figure 3.3. FIGURE 3.3 TYPICAL EVAPORATION POND CONFIGURATION OF MECHANICAL MIST EVAPORATOR

Evaporation ponds and mechanical misters are proven industrial and wastewater technologies that provide a simple, reliable solution to brine concentrate management. However, evaporation ponds have a large footprint and are climate sensitive. In addition, evaporation ponds could pose regulatory, aesthetic, environmental, and ecological issues; additionally, mechanical misters could pose noise and air quality issues. Precipitated salts have to be transferred to a landfill for final disposal.

A major concern about mist-enhanced evaporation is that the mist and small salt particulate matter can to drift away from the evaporation pond at very low wind velocities, and negate the purpose of zero discharge.

Similar to the evaporation ponds, capital cost is sensitive to project location and location specific evaporation and rainfall data which determines surface area requirement for evaporation pond. Mister type and size have impact on both capital and operating costs.

For example; the capital and O&M costs for treating 1.0-mgd concentrate flow via an evaporation pond located in Irvine are approximately $26,000,000 and $1,060,000/year, respectively. Mister use can dramatically reduce foot-print and hence capital cost for the project but it nearly triples the O&M cost. Capital cost estimates for the enhanced evaporation ponds were provided by CH2M HILL and Slimline Manufacturing, Inc.



3.4 Wind-Aided Intensified Evaporation

Wind-Aided Intensified Evaporation is an enhanced evaporation process that uses wind energy to reduce the land area required for brine-concentrate disposal. The WAIV process sprays brine concentrate over vertically mounted and continuously wetted evaporation surfaces that have a high packing density footprint (20 m2/m2 footprint or larger) (Gilron, 2003). This concept is based on exploiting wind energy to enhance evaporation rates.

Three different evaporation surfaces have been tested for use in the WAIV process, they are:

• Woven nettings • Nonwoven geotextiles • Tuff (volcanic rock)

Pilot testing has found that materials with less internal surface areas, such as nonwoven geotextiles are less susceptible to clogging of the surface compared to materials with large internal surface areas (that is, woven nettings).

Figure 3.4 shows the configuration of a WAIV pilot unit. The WAIV unit has vertically mounted evaporation surfaces placed in arrays. Deploying the evaporation surfaces in arrays with large lateral dimensions significantly increases the height and depth across which the wind passes. This results in the wind coming into contact with a greater surface area prior to saturation with vapor. The pilot study found that this resulted in a tenfold increase in evaporative capacity per footprint area (Gilron, 2003). FIGURE 3.4 WAIV PILOT UNIT

The WAIV process works best in a climate with high evaporation rates. Another important component of implementing the WAIV process is the selection of suitable materials for evaporation surfaces. Suitable materials should have a packing density high enough to enhance evaporation while not causing unnecessary wind blockage. Prior to implementation of this technology a detailed pilot testing program should be



undertaken to ensure this technology is feasible for brine concentrate management at a specific site.

The potential advantages of the WAIV technology include:

• Land requirement is reduced in comparison to evaporation ponds due to enhanced evaporation rates.

• Natural energy sources (solar and wind) are used resulting in lower O&M costs.

• Operation is less complex compared to MTE and RO based concentrate management options.

The disadvantages of this technology are:

• Technology is still under development. • Surface material and packing density need to be optimized. • No full-scale performance and capital and O&M data exist. • Technology is ineffective in climates with low evaporation rates. • Periodic rinsing and acid wash are required for cleaning of woven surfaces. • Residuals need to be disposed of in landfills.

3.5 Dewvaporation

Dewvaporation is a process that combines dew formation and evaporation processes to purify water. The concept was developed at Arizona State University in conjunction with L'Eau LLC, the company that owns the patent rights to the process. Dewvaporation works by using heated air to evaporate water from brackish water. Each Dewvaporation tower contains a heat transfer wall made of plastic material. The wall divides the module into two compartments, one for evaporation and one for dew formation. The tower unit is built of thin plastic materials to avoid corrosion and to minimize equipment costs. Using this tower configuration lowers the cost because the tower operates at atmospheric pressure.

The process works by introducing wastewater or salty water down the evaporation side of the heat transfer wall; then an external blower is used to move the stream upward. Heat coming through the heat transfer wall causes most of the water to evaporate. Evaporation occurs at the liquid-air interface and not at the heat transfer wall, which minimizes scaling problems. The remainder of the water, which will have concentrated salts, exits from the bottom of the module.

At the top of the tower, humid air mixes with a stream of steam and flows into the dew formation module. Heat flows through the heat transfer wall into the evaporation module, cooling the warm air and allowing dew (distilled water) to form. The distilled water flows out the bottom of the module as shown in Figure 3.5. Heat sources for dewvaporation can be combustible fuel, solar, or waste heat. Dewvaporation has been pilot tested extensively; however, no full-scale application of this process for desalination and RO concentrate treatment exists.



FIGURE 3.5 A SIMPLIFIED PROCESS SCHEMATIC OF DEWVAPORATION

Source: L’Eau LLC, 2009

The potential advantages of Dewvaporation include:

• Dewvaporation produces high-quality (distilled) water.

• Solar or waste heat can be used to power the unit.

• Operation is less complex than MTE and RO based concentrate management options.

• Operation cost is low due to moderate operating temperature and atmospheric pressure.

• Plastics heat transfer walls reduce capital cost and eliminate corrosion concerns.

The potential advantages of this technology include:

• No full-scale units are in service,

• No data exist on full-scale performance or on capital and O&M costs.

• Dewvaporation results in lower water recovery (30 to 40 percent).

3.6 Salt Solidification and Sequestration (SAL-PROC)

SAL-PROC™ is a patented process of Geo-Processors USA, Inc. (Glendale, California). It is an integrated process for the sequential or selective extraction of dissolved elements from saline waters in the form of valuable salts and chemical compounds (mineral, slurry, and liquid forms). The process involves multiple



evaporation and/or cooling steps supplemented by conventional mineral and chemical processing. This technology is based on simple closed-loop processing and fluid flow circuits, which enable the partial or comprehensive treatment of inorganic saline streams for recovery of valuable by-products. Field trials and pilot testing indicated that a number of saline waste streams can be converted into marketable products (precipitated salts) while achieving zero liquid discharge. The chemicals typically recovered from saline streams include gypsum-magnesium hydroxide, magnesium hydroxide, sodium chlorite, calcium carbonate, sodium sulfate, and calcium chloride. A simplified SAL-PROC process schematic is illustrated in Figure 3.6. FIGURE 3.6 A SIMPLIFIED PROCESS SCHEMATIC OF SAL-PROC™

Geo-Processor has developed a model that consists of two subsystems, including one or more selective salt recovery steps that are linked with RO desalination, thermo-mechanical brine concentration, and crystallization steps. The desktop modeling exercise enables the selection of an appropriate ZLD process scheme. The selected ZLD systems utilize multiple reaction steps using lime and soda ash to produce carbonated magnesium, calcium carbonate, and a mixed salt. The overall system recovers the entire flow and can generate high-quality water. However, SAL-PROC requires incorporation of one or more desalting technologies to reduce volume significantly while highly concentrating water entering the SAL-PROC.

SAL-PROC is not a stand-alone brine concentrate treatment technology. This process acts as a product recovery process. The suitability of using SAL-PROC depends upon the water quality and type of application. RO concentrate from water reuse facilities might not be permitted to recover products because wastewaters contain organic, toxic, and hazardous material. The major advantage of implementing this process is that it can recover marketable products. Cost data for SAL-PROC is not available.


4 Final Disposal Options Final disposal options are concentrate management technologies that require no additional management technology. The following final disposal options result in the concentrate being discharged into the ocean, a nonpotable groundwater location, or disposed in a landfill. These options are: deep well injection, ocean discharge (existing and new), downstream discharge to wastewater treatment plant or disposal station, and disposal to landfills. Each of these concentrate management technologies requires regulatory approval prior to discharge. The following subsection will discuss each of the technologies including the regulatory approvals required prior to disposal.

4.1 Deep Well Injection

Deep well injection (DWI) is a concentrate management technology that uses subsurface geologic formations that are not otherwise drawn on for beneficial purposes (that is, nonpotable groundwater sources, such as areas where oil and/or gas have been extracted) to store liquid concentrate. A well is used to convey the liquid concentrate some distance below the ground surface where it is released into a geologic formation. The depth of the well is typically less than 8,000 feet, depending on the class of well used, the existing geologic strata, and the depth to groundwater aquifers. In particular, injection of concentrate into abandoned oil or gas wells could be a disposal option if the well complies with regulatory standards to protect the USDW.

Implementation issues for concentrate disposal by DWI include site availability, well classification, concentrate compatibility, and public perception. The site must have favorable underground geology conducive to DWI, with a porous injection zone capable of sustaining adequate injection rates over the life of the membrane facility. In addition, an impermeable layer is required to prevent the migration of the injected concentrate into a USDW. The site should be a sufficient distance from any wells going through the impermeable layer that could serve as a pathway to a USDW.

DWI has a proven history in municipal and industrial applications. For example, Laguna County Sanitation District disposes of concentrate from an RO membrane into a Class I nonhazardous injection well. The major advantage of using DWI is that it requires minimal land area and can utilize abandoned well sites, which would reduce costs for infrastructure. However, DWI is feasible only in specific geological and site conditions. One important consideration regarding the use of DWI is proximity to faults because injecting concentrate could increase water pressure on fault lines resulting in earth movement. Figures 4.1 to 4.5 show the locations of faults in southern California. In addition, DWI requires extensive O&M because fluid confinement must be proven and maintained, capacity reduction due to plugging could occur over time, repairing leaks or abandoning wells could be



difficult, and treatment plant complexity could add more manpower time. Existing DWI wells in southern California achieve injection rates of approximately 60 to 100 gpm, with decreasing injection rates over time. Reduction in injection rate over time is caused by clogging and can be reversed with periodic well redevelopment.

Capital and O&M costs for DWI are site specific. Capital costs to retrofit abandoned oil and gas wells for DWI in California vary from $600,000 to $1,000,000 per well, including permitting. Capital costs to install a new DWI site are approximately $800,000 to $2,160,000 per well, including permitting. These estimates for capital costs do not include well testing, which will vary based on the well. Well testing could include pump testing, mechanical integrity testing, geophysical surveys, and geochemistry analyses. Table 4.1 summarizes capital costs based on the size of the well.

TABLE 4.1 WELL INJECTION CAPITAL COST MATRIX

Type of DWI Well Capital Costa ($)

Abandoned Oil and Gas Well Retrofit $1,00,000

Install New DWI Well $2,160,000

Note: Capital Cost based on 1 well.

Well testing costs can vary greatly depending on the age and location of the well, and well rehabilitation could be required on a periodic basis due to loss of injection capacity. Additional factors that could affect the cost are high-pressure injections, quality of injection water, and the quality of the receiving aquifer matrix and water. Table 4.2 provides the O&M costs for retrofitting an abandoned well to a DWI.

TABLE 4.2 DEEP WELL INJECTION OPERATION AND MAINTENANCE COSTS

Component

Costa

$/yr

Power $432,000

Parts and Maintenance $317,000b

Chemicals and Other $190,000

Total $939,000

Note: a O&M costs are for a 1-mgd flow. b For a new well Parts and Maintenance costs would be $557,000, which increases the total O&M cost for a new well to $1,179,000.

SAN FERNANDO VALLEY BASIN

Ventura County Basins

PIRU

FILLMORE

NORTH LAS POSAS

MOUND SIMI VALLEY

OXNARD PLAN PRESSURE BASIN

SANTAPAULA

PLEASANT VALLEY

SANTA CLARA RIVER VALLEY-EASTERN BASIN

SOUTH LAS POSAS

LOWER VENTURA

RIVER

OXNARD PLAIN

FOREBAY SANTA ROSA BASIN

MUGU FOREBAY

FIGURE 4.1 - FAULTS IN VENTURA COUNTY REGIONSOUTHERN CALIFORNIA REGIONAL BRINE-CONCENTRATE MANAGEMENT STUDY - PHASE I ±


0 2.5 5Miles

Groundwater BasinsFillmoreLower Ventura RiverMoundMugu Forebay

North Las PosasOxnard Plain ForebayOxnard Plain PressurePiruPleasant Valley

Santa PaulaSanta RosaSimi ValleySouth Las Posas

FeaturesFault Location (Approximate)RiversWater BodiesBedrock

San Fernando Valley Basin

San GabrielBasins

West CoastBasins

Orange CountyBasins

Chino Basins

CLAIREMONT-LIVE OAKS-POMONA-SPADRA

CENTRAL

SAN GABRIEL

WEST COAST

RAYMOND

SANTA MONICA

SANTA CLARA RIVER VALLEY-EASTERN BASIN

HOLLYWOOD

ACTON VALLEY BASIN

SAN


FIGURE 4.2 - FAULTS IN LOS ANGELES COUNTY REGIONSOUTHERN CALIFORNIA REGIONAL BRINE-CONCENTRATE MANAGEMENT STUDY - PHASE 1

±

Groundwater Basins

CentralClaremont-Live Oaks-Pomona-SpadraHollywoodRaymond

San Fernando ValleySan GabrielSanta MonicaWest Coast

Features

Fault Location (Approximate)RiversWater BodiesBedrock

0 4 8Miles

West CoastBasins

Orange CountyBasins

Riverside Basins

San Diego Basins

SAN JUAN

SANTA ANA FOREBAY

SANTA ANA PRESSURE

IRVINE PRESSURE

IRVINE FOREBAY

IRVINE FOREBAY 2

IRVINE FOREBAY 2


FIGURE 4.3 - FAULTS IN ORANGE COUNTY REGIONSOUTHERN CALIFORNIA REGIONAL BRINE-CONCENTRATE MANAGEMENT STUDY - PHASE 1 ±0 2.5 5

Miles

Groundwater Basins

Irvine ForebayIrvine Forebay 2Irvine Pressure

San JuanSanta Ana ForebaySanta Ana Pressure

Features

Fault Location (Approximate)RiversWater BodiesBedrock

Chino Basins

Bunker HillBasins

Riverside Basins

San Diego

San Diego Basins

Orange CountyBasins

CHINO

RIVERSIDE

BUNKER HILL

SAN TIMOTEO

TEMECULA VALLEY

HEMET

TEMESCAL

BEDFORD

ARLINGTON

CAJALCO

LEE LAKE

PERRIS NORTH

RIALTO-COLTON

ELSINORE

CUCAMONGA

LAKEVIEW

LYTLE

ESCONDIDO

PERRIS SOUTH 2

TERRA COTTA

MENIFEE

COLDWATER

CLAREMONT-LIVE OAKS-POMONA-SPADRA

WINCHESTER

PERRIS SOUTH 1

DEVIL CANYON

SAN JACINTO INTAKE AND UPPER PRESSURE

LOWER CANYON

SAN JACINTO LOW PRESSURE

PERRIS SOUTH 3

SAN JACINTO CANYON

BATIQUITOS LAGOON

UPPER RIALTO-COLTON


FIGURE 4.4 - FAULTS IN INLAND EMPIRE REGIONSOUTHERN CALIFORNIA REGIONAL BRINE-CONCENTRATE MANAGEMENT STUDY - PHASE 1 ±

0 4 8Miles

Groundwater BasinsArlington

Bedford

Bunker Hill

Cajalco

Chino

Claremont-Live Oaks-Pomona-SpadraColdwater

Cucamonga

Devil Canyon

Elsinore

Hemet

Lakeview

Lee Lake

Lower Canyon

Lytle

Menifee

Perris North

Perris South 1

Perris South 2

Perris South 3

Rialto-Colton

Riverside

San Jacinto Canyon

San Jacinto Intakeand Upper Pressure

San Jacinto Low Pressure

San Timoteo

Temecula Valley

Temescal

Terra Cotta

Upper Rialto-Colton

Winchester

FeaturesFault Location(Approximate)

Rivers

Water Bodies

Bedrock

Orange CountyBasins

Riverside Basins

San Diego Basins

San Diego Basins

REBAY

HEMET

WARNER

TEMESCAL

RE

BEDFORD

CAJALCO

SAN FELIPE

LEE LAKE

SAN LUIS REY

ELSINORE

SAN DIEGO FORMATION

LAKEVIEW

E PRESSURE

ESCONDIDO

PERRIS SOUTH 2

TERRA COTTA MENIFEE

EL CAJON

COLDWATER

IRVINE FOREBAY

SAN MATEO

SAN JUAN

MISSION VALLEY

TIA JUANA

SANTA MARIA VALLEY

WINCHESTER

PERRIS SOUTH 1

SANTA MARGARITA

IRVINE FOREBAY 2

LAS PULGAS

SAN DIEGO RIVER VALLEY

CHIHUAHUA

SAN JACINTO INTAKE AND UPPER PRESSURE

COLLINS VALLEY

SAN ONOFRE

GARNER VALLEY

SAN PASQUAL

SWEETWATER

COTTONWOOD VALLEY

SAN JACINTO LOW PRESSURE

SAN DIEGUITO MASON VALLE

IRVINE FOREBAY 2 IDYLLWILDPERRIS SOUTH 3

CARMEL VALLEY

SAN JACINTO CANYON

SAN ELIJO LAGOON

BATIQUITOS LAGOON


Groundwater BasinsBatiquitos LagoonCarmel ValleyEl CajonEscondidoLas Pulgas

Mission ValleySan Diego FormationSan Diego River ValleySan DieguitoSan Elijo LagoonSan Juan

San Luis ReySan MateoSan OnofreSan PasqualSanta MargaritaSanta Maria Valley

SweetwaterTia JuanaWarner

FeaturesFault Location(Approximate)RiversWater BodiesBedrock

FIGURE 4.5 - FAULTS IN SAN DIEGO COUNTY REGIONSOUTHERN CALIFORNIA REGIONAL BRINE-CONCENTRATE MANAGEMENT STUDY - PHASE 1

±0 6 12

Miles



The primary driver for regulation of concentrate discharged through DWI is public health. Groundwater is or could be used as a drinking water source, and drinking water standards often are applied to concentrate when it is discharged through DWI.

The Underground Injection Control (UIC) program was developed to protect USDW and is administered by the United States Environmental Protection Agency (USEPA) and the California Regional Water Quality Control Boards (RWQCBs). In Title 40 of the Code of Federal Regulations (CFR) Part 146 of the UIC program lays out a classification system for injection wells. The UIC provides standards, technical assistance, and grants to state governments to regulate injection wells to prevent contamination of drinking water sources. Five classes of wells are described in Table 4.3 and illustrated in Figure 4.6. The different classes of wells are categorized by the origin and characteristics of the liquid waste.

Class I, II, and III wells must comply with the following:

• Be in a location that is free of faults or other adverse geologic features • Be drilled to depths so that injected fluids do not affect a potential USDW and be

confined from any formation that potentially could be a USDW • Be tested for integrity of the well at the time of completion and every 5 years

thereafter • Be monitored continuously to assure well integrity TABLE 4.3 CLASSES OF INJECTION WELLS

Class Description

I Injectate equal to or greater than 10,000 mg/L TDS Geologic confining layer present to prevent contamination of upper level USDW Injectate could have a poorer quality than the USDW into which it is being injected

II Wells used in the recovery of natural gas or oil

III Wells used to inject super-heated steam, water, or other fluids into formation to extract minerals

IV Wells used to dispose of radioactive waste (banned under UIC Program)

V Wells used to inject fluids not classified in other well classes (for example, advanced wastewater disposal systems, disposal of septic systems, or stormwater, agricultural, and industrial drainage wells) Injectate is of greater quality than the water into which it is being injected Injectate is less than 10,000 mg/L TDS

In California, the California Department of Conservation, Division of Oil, and Geothermal Resources regulates Class II wells, and USEPA regulates Classes I, III, IV, and V wells. Concentrate disposal can use Class I or V wells; however, permitting a Class V well could be difficult because these are typically low-technology wells and use gravity to supply the well. In addition, it is unlikely that in southern California a Class V well would be permitted because concentrate would contaminate a potential USDW. A USDW is defined as any underground aquifer containing water with TDS less than 10,000 mg/L.



FIGURE 4.6 CLASSES OF INJECTION WELLS

Source: USEPA, 2008

Class I Class II Class III

Class IV

Class V



To permit a Class I well, the project proponent must show, through extensive geologic testing and modeling, that injected water quality will not degrade the USDW. Class I injection wells must have special protection against contamination of the USDW. The permitting process for an injection well can be a labor-intensive process. The permitting process involves drilling a test well that is completed to Class I standards. Permit requirements for a Class I injection well as stipulated under Subpart B, Section 146.12, of the UIC regulations state:

All Class I wells shall be sited in such a fashion that they inject into a formation which is beneath the lowermost formation containing, within 0.25 mile of the well bore, an underground source of drinking water.

In addition, an impermeable geologic stratum must be located above the injection zone to prevent the migration of the injectate into an overlying USDW. Extensive geologic modeling might be required to demonstrate the effectiveness of the impermeable strata in preventing migration. In many cases, geologic investigations are required to collect data used for modeling purposes.

USEPA requires that Class I wells be placed in areas free of vertically transmissive faults and fissures and that the region be characterized by low seismicity and a low probability of earthquakes. In California, locating a site that could be shown to have no faults or fissures and a low probability of earthquakes would be difficult. In other regions, DWI has resulted in a rise in pore pressures and activation of faults, causing increased seismicity. Proving that seismicity would not increase as a result of any given project would be difficult. Figures 4.7 to 4.11 show the locations of oil and gas wells. These wells can potentially be used for DWI if site-specific hydrogeological conditions comply with regulatory requirements.

If suitable geology is determined to be present, a test well is drilled, completed, and used to confirm adequate injection capacity. The test well typically is completed to Class I standards, but initially permitted as a Class II well to expedite the permit process.

A typical Class I injection well consists of concentric pipes that extend several thousand feet below the ground surface into a highly saline, permeable, injection zone that is vertically confined by impermeable strata. The outermost pipe or surface casing extends below the base of any USDW and is cemented to the surface to prevent contamination of the USDW. Directly inside the surface casing is a long, string casing that extends to and sometimes into the injection zone. This casing is cemented to the surface to seal the injected waste from the formations above the injection zone. If the well is determined suitable for DWI, it can be reclassified as a Class I well. Figure 4.12 is a schematic of a deep injection well.

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Somis Desalter

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FIGURE 4.7 - OIL AND GAS WELLS IN VENTURA COUNTY REGIONSOUTHERN CALIFORNIA REGIONAL BRINE-CONCENTRATE MANAGEMENT STUDY - PHASE I

Wastewater Treatment Plants#* Land Discharge

#* Recycled Water Only

# Stream Discharge

#* Ocean Discharge

#* Other

Oil and Gas WellsOil and Gas Wells

Desalination Facilities

&3 Existing Groundwater Desalter

Planned Groundwater Desalter

" Proposed Seawater Desalination Plant

Industrial Ocean OutfallsPower PlantsIndustrial/Others

Wastewater OutfallsWastewater Outfalls

Planned or Potential Ocean Outfall

Existing Brineline or Interconnector Sewer

Planned or Potential Brineline or Interconnector Sewer

FeaturesHighways

Rivers

Water Bodies

Groundwater BasinsFillmoreLower Ventura RiverMoundMugu Forebay

North Las PosasOxnard Plain ForebayOxnard Plain PressurePiruPleasant ValleySanta PaulaSanta RosaSimi ValleySouth Las Posas

±0 2.5 5

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Marvin C. Brewer Desalter

Tustin Desalter

Frances Desalter

Baker WTP

Irvine Principal Potable Treatment Plant (P

Irvine Non-Potable Shallow Groundwater U

Upland Ion Exchange Facility

Pomona Ion Exchange Facility

Ch

Chino Desalter I

Temescal Desalter

WRP

Hill Canyon WWTP

Simi Valley WQCP

Ahmanson Ranch

Tapia WRF

Donald C. Tillman WRP Burbank WRP

Los Angeles/Glendale WRP

Edward C. Little WRF

Hyperion WWTP

Whittier Narrows WRP

San Jose Creek WRP

Los Coyotes WRP

Carson Regional WRP

Joint WPCP

Long Beach WRP

Leo J. Vander Lans Treatment Facility

Terminal Island WWTP

OCSD Plant #1

Green Acres ProjectMichelson WRP

Pomona WRP

IEUA Regional Plant #1

Western R

Corona WWTP #1

Corona WW

Carbon Canyon WRP

Chino Institution For Men


Corona WWTP #

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Hyperion 1-mile Bypass Outfall

Hyperion 5- mile Outfall

Brewer Desalter Outfall

Terminal Island Outfall

Joint Outfall

Carson Refinery

El Segundo Refinery

Haynes Generating Station

Harbor Generating Station

Redondo Generating Station

Long Beach Generating Station

El Segundo Generating Station

Scattergood Generating Station

Ontario Ion Exchange

Monte Vista WD Ion Exchange

West Simi Valley Desalter

Wells 21 & 22

llo Groundwater Desalter (Wells A & B)

South Las Posas Desalter (Moorpark Desalter)

ater Desalter

Chevron PlantExxon Mobil Plant

La Canada WRP

Groundwater Reliability Improvement Program (GRIP)

Malibu Mesa WRF

Newhall Ranch WRP

West Basin WRP - Barrier Treatment

Malibu WPCPTrancas WPCP

Beverly Hills Desalter

Chino Ion Exchange Facility


FIGURE 4.8 - OIL AND GAS WELLS IN LOS ANGELES COUNTY REGIONSOUTHERN CALIFORNIA REGIONAL BRINE-CONCENTRATE MANAGEMENT STUDY - PHASE I



# Stream Discharge

#* Ocean Discharge

#* Other






Industrial Ocean OutfallsPower Plants

Industrial/Others





FeaturesHighways

Rivers

Water Bodies

Groundwater BasinsCentral

Claremont-Live Oaks-Pomona-Spadra

Hollywood

Raymond

San Fernando Valley

San Gabriel

Santa Monica

West Coast

±0 4 8Miles


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er Desalter

Tustin Desalter

Frances Desalter

Baker WTP

Irvine Principal Potable Treatment Plant (PPTP) Desalter

Irvine Non-Potable Shallow Groundwater Unit (SGU) Desalter

City of San Juan Capistrano Groundwater Desalter

South Orange Coastal Ocean Desalination Project

Temescal Desalter

Anita Smith Ion Exchange FacilityTP Los Coyotes WRP

egional WRP

Long Beach WRP


OCSD Plant #1

Green Acres Project

Groundwater Replenishment System

OCSD Plant #2

Michelson WRP

Los Alisos WRP

El Toro WWTP

Regional Treatment Plant

Coastal Treatment Plant

3A Plant

Oso Creek WRP

Chiquita WRP

Robinson Ranch WRP

Jay B Latham WWTP

Camp Pendleton WWTP #12




Fa

Camp Pe

Camp Pen

San Luis Rey WWCamp Pendleton WWTP #13

Corona WWTP #1

Corona WWTP #3Western Water Recycling Facility

Lake Elsinore Regional WWRF

Railroad Canyon WWRF

San Clemente WRP

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§̈¦405

§̈¦5

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tu55

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tu22

tu91

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AES Huntington Beach Power Generation Fac. Outfall

OCSD Outfall #1

OCSD Outfall #2

Aliso Creek Ocean Outfall

San Juan Creek Ocean Outfall

Huntington Beach Generating Station

SONGS UNIT 3

SONGS UNIT 2

Carson Refinery



Wells 21 & 22

Lee Lake Water DistrictHorsethief Canyon

AlberhillEVMWD Regional Was

Nichols Water Reclamation Plant

Camp Pendleton - Northern Tertiary Treatment Plant

Deep Aquifer Treatment Plant (DATS)

FIGURE 4.9 - OIL AND GAS WELLS IN ORANGE COUNTY REGIONSOUTHERN CALIFORNIA REGIONAL BRINE-CONCENTRATE MANAGEMENT STUDY - PHASE I



# Stream Discharge

#* Ocean Discharge

#* Other






Industrial Ocean OutfallsPower Plants

Industrial/Others





FeaturesHighways

Rivers

Water Bodies

Groundwater BasinsIrvine Forebay

Irvine Forebay 2

Irvine Pressure

San Juan

Santa Ana Forebay

Santa Ana Pressure

±0 3 6Miles

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#*#*#*

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#*

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#*

Tustin Desalter

Frances Desalter

Baker WTP

Irvine Principal Potable Treatment Plant (PPTP) Desalter

Irvine Non-Potable Shallow Groundwater Unit (SGU) Desalter



Upland Ion Exchange Facility

Pomona Ion Exchange Facility

Chino Desalter II

Chino Desalter III

Chino Desalter I

Lower Bunker Hill

Yucaipa Valley Regional Water Supply Renewal Project

Temescal Desalter

Arlington Desalter

Anita Smith Ion Exchange Facility

Menifee Desalter

Perris Desalter II

Perris Desalter I

es/Glendale WRP

Whittier Narrows WRP

San Jose Creek WRP

Los Coyotes WRP

Long Beach WRP


WWTP

OCSD Plant #1

Green Acres Project

Groundwater Replenishment System

OCSD Plant #2

Michelson WRP

Los Alisos WRP

El Toro WWTP

Regional Treatment Plant

Coastal Treatment Plant

3A Plant

Oso Creek WRP

Chiquita WRP

Robinson Ranch WRP

Jay B Latham WWTP





Fallbrook Plant #1



Pomona WRP



Rialto WWTPRIX WRP

Colton WWTP

San Bernardino WRP Redlands WWTP

Riverside Regional WQCP

Western Riverside Co WWTP

Corona WWTP #1 Corona WWTP #2

Carbon Canyon WRP

Chino Institution For MenIEUA Regional Plant #5

Corona WWTP #3Western Water Recycling Facility

Moreno Valley WRF

Perris Valley WRP

Lake Elsinore Regional WWRF

Railroad Canyon WWRF

Hemet/San Jacinto WRF

Santa Rosa WRF

Temecula Valley Regional WRF

Banning WWRP

Beaumont WWTP #1

Henry N. Wocholz WWTP

Running Springs

Stringfellow Pretreatment Facility

Chino Hills Ion Exchange Facility

San Clemente WRP

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tu30

sland Outfall

untington Beach Power Generation Fac. Outfall

OCSD Outfall #1

OCSD Outfall #2



Huntington Beach Generating Station

SONGS UNIT 3

SONGS UNIT 2

Carson Refinery



Ontario Ion Exchange

Monte Vista WD Ion Exchange

Wells 21 & 22

Rainbow MWD Desalination Facility

Lee Lake Water DistrictHorsethief Canyon

AlberhillEVMWD Regional Wastewater Reclamation Plant

Groundwater Reliability Improvement Program (GRIP)



Deep Aquifer Treatment Plant (DATS)

Chino Ion Exchange Facility

Inland Empire Energy Center

FIGURE 4.10 - OIL AND GAS WELLS IN INLAND EMPIRE REGIONSOUTHERN CALIFORNIA REGIONAL BRINE-CONCENTRATE MANAGEMENT STUDY - PHASE I

Wastewater Treatment Plants

#* Land Discharge


# Stream Discharge#* Ocean Discharge

#* Other



&3 Existing Groundwater DesalterPlanned Groundwater Desalter



Wastewater OutfallsWastewater OutfallsPlanned or Potential Ocean OutfallExisting Brineline or Interconnector SewerPlanned or Potential Brineline or Interconnector Sewer

FeaturesHighwaysRiversWater Bodies

Groundwater BasinsArlingtonBedfordBunker HillCajalco

ChinoClaremont-Live Oaks-Pomona-SpadraColdwaterCucamongaDevil CanyonElsinoreHemetLakeviewLee Lake

Lower CanyonLytleMenifeePerris NorthPerris South 1Perris South 2Perris South 3Rialto-ColtonRiversideSan Jacinto Canyon

San Jacinto Intakeand Upper PressureSan Jacinto Low PressureSan TimoteoTemecula ValleyTemescalTerra CottaUpper Rialto-ColtonWinchester

±0 4 8Miles


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Mission Basin Desalting Facility

Richard Reynolds GW Demineralization Facility

North River Groundwater Desalter

Coastal Treatment Plantq

Jay B Latham WWTP





Fallbrook Plant #1



San Luis Rey WWTPCamp Pendleton WWTP #13

La Salina WWTP

Lower Moosa Canyon WRF

Valley Center WWTP

Hale Avenue WRFMeadowlark WRP

Gafner WRF

Carlsbad WRPEncina WPCF

Santa Maria WPCF4-S Ranch WTP

Rancho Santa Fe WPCFFairbanks Ranch WPCF

Whispering Palms WPCF

San Elijo WRF

North City WRP Padre Dam WRF

Ralph W Chapman WRFPoint Loma WWTP

Temecula Valley Regional WRF

San Clemente WRP

South Bay WWTP

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Oceanside Outfall

Encina Outfall Pipeline

San Elijo Ocean Outfall

Point Loma Outfall

South Bay Ocean Outfall

Proposed Camp Pendleton Outfall

SeaWorld 2

SeaWorld 1

SONGS UNIT 3

SONGS UNIT 2

Encina Power Plant

Naval Base San Diego

South Bay Power Plant

US Naval Base Point Loma

US Naval Base Coronado

National Steel & Shipbuilding

Skyline Ranch WRFCamp Pendleton AWT Plant

San Pasqual Groundwater Desalter

Mission Valley Groundwater Desalination Project

Rainbow MWD Desalination Facility

Ramona Desalting Facility

Rancho Del Rey Well Desalination

San Diego Formation Groundwater Desal Facility

San Dieguito Desalting Facility

Santee Desalination Facility



Camp Pendleton - Southern Tertiary Treatment Plant

Otay River Desalination Plant

Chula Vista MBR Treatment Plant


FIGURE 4.11 - OIL AND GAS WELLS IN SAN DIEGO COUNTY REGIONSOUTHERN CALIFORNIA REGIONAL BRINE-CONCENTRATE MANAGEMENT STUDY - PHASE I

Wastewater Treatment Plants#* Land Discharge#* Recycled Water Only# Stream Discharge#* Ocean Discharge#* OtherOil and Gas Wells

Oil and Gas Wells


&3 Existing Groundwater DesalterPlanned Groundwater Desalter





Groundwater BasinsBatiquitos LagoonCarmel ValleyEl CajonEscondidoLas PulgasMission ValleySan Diego FormationSan Diego River ValleySan DieguitoSan Elijo Lagoon

San JuanSan Luis ReySan MateoSan OnofreSan PasqualSanta MargaritaSanta Maria ValleySweetwaterTia JuanaWarner

±0 4 8

Miles

SOUTHERN CALIFORNIA REGIONAL BRINE-CONCENTRATE MANAGEMENT STUDY – PHASE I TREATMENT AND DISPOSAL OF BRINE-CONCENTRATE REPORT


FIGURE 4.12 SCHEMATIC OF A DEEP INJECTION WELL

Injection Zone

Impermeable Zone

Impermeable ZonePacker

Annular SpaceFilled with InertFluid

Wastewater

ConcentratePressure Gauge

Annular FluidPressure Gauge

Surface Casing

Inner Casing

Injection Casing

Land Surface

Some constraints when using DWI include: • Injection might not be feasible in areas where seismic activity could occur and

cause seepage at faults. • Injected wastes must be compatible with the mechanical components of the

injection well system and the natural formation water. Pretreatment of injectate could be required to ensure compatibility with geologic formation and the receiving water.

• High concentrations of suspended solids (typically more than 2 ppm) can lead to plugging of the injection area of the well.

• Organic carbon could serve as an energy source for indigenous or injected bacteria, which could result in rapid population growth and subsequent fouling.



• Concentrate streams containing sparingly soluble salts including silica, above their respective solubility limits, could require pretreatment before injection into a well.

4.2 Disposal via Wastewater Treatment Facility

In California, concentrate can be disposed of into a sewer system. However, concentrate disposal might be limited at local sewage systems because of potential detrimental effects on the ability of wastewater plants to comply with requirements of the National Pollutant Discharge Elimination System (NPDES).

4.2.1 Concentrate Blending Blending some or all of the RO concentrate with wastewater influent is a common RO concentrate disposal method. Blending reduces or eliminates treatment needs, as long as wastewater treatment plant (WWTP) NPDES permit limits are fully satisfied. The amount of RO concentrate flow that can be blended with secondary effluent or WWTP flow depends upon the RO concentrate flow and quality, as well as WWTP flows, wastewater quality and permit limits.

Capital cost for concentrate blending is highly project specific. For small applications, the facility cost may include construction of a small pipe-line that is connected to the secondary effluent for blending.

4.3 Ocean Disposal

Southern California has over 80 facilities that discharge to the ocean, as seen in Figure 4.13. In addition, six facilities discharge to other WWTPs via interceptors. A majority of these facilities discharge a mixture of wastewater effluent and/or brine concentrate (for example, the Orange County Sanitation District outfall). All ocean outfalls are permitted under NPDES permits. NPDES permit requirements for ocean discharges are focused primarily on habitat effects on marine organisms and most commonly include requirements for total suspended solids (TSS), biochemical oxygen demand (BOD), toxicity, and residual chlorine.

The NPDES limits for refineries and power plants have more stringent requirements for metals and other constituents because these outfalls are typically short, shallow, and do not have diffusers as seen in Figure 4.14. For this reason, this type of outfall has more stringent water quality objectives in the outfall NPDES permit because the permit uses standards based on the Ocean Plan. For example, several metal parameters (i.e., Chromium, Copper, Silver and Mercury) have water quality objectives in the Ocean Plan which are more stringent and well below drinking water quality standards. Table 4-4 provides concentrate water quality examples for a brackish water RO and wastewater RO facility. The water quality data are based on water quality projections for Menifee Desalter and GWRS RO concentrate. Table 4-4 also presents Ocean Plan water quality objectives along with Federal Drinking Water Standards.

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tu62

tu18

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tu38

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tu30Ventura Region

Los Angeles Region

South OrangeCounty Region

North Orange County Region

San Diego Region

Inland Empire Region

Oxnard Ocean OutfallOrmond Beach Effluent Pipeline

(Reliant Energy LLC)

Private Industrial Outfall #2Private Industrial Outfall #1

Hyperion 1-mile Bypass OutfallHyperion 5- mile Outfall

Brewer Desalter Outfall

Terminal IslandOutfall

Joint OutfallAES Huntington Beach Power Generation Fac. Outfall

OCSD Outfall #1

OCSD Outfall #2



Oceanside Outfall

Encina Outfall Pipeline

San Elijo Ocean Outfall

Point Loma Outfall

South Bay Ocean Outfall

HuenemeOutfall

Proposed CampPendleton Outfall


FIGURE 4.13 - EXISTING OCEAN OUTFALLS IN SOUTHERN CALIFORNIASOUTHERN CALIFORNIA REGIONAL BRINE-CONCENTRATE MANAGEMENT STUDY - PHASE I ±

0 10 20Miles

Wastewater Treatment Plants#* Land Discharge#* Recycled Water Only# Stream Discharge#* Ocean Discharge#* Other

Desalination Facilities&3 Existing Groundwater Desalter

Planned Groundwater Desalter" Proposed Seawater Desalination Plant






FIGURE 4.14 TYPICAL POWER PLANT OUTFALL CONFIGURATION

Source: Calleguas Municipal Water District, 2008

TABLE 4.4 RO CONCENTRATE WATER QUALITY EXAMPLES, OCEAN PLAN OBJECTIVES AND FEDERAL DRINKING WATER STANDARDS

Parameter Unit Brackish Water RO Concentrate Water Qualitya

Wastewater RO Concentrate

Water Qualityb

Ocean Plan Water Quality

Objectives

National Drinking Water

Regulations

Total Organic Carbon (TOC) mg/L 1.5 69

Total Hardness (CaCO3) mg/L 3,500 1,920 - -

Calcium (Ca) mg/L 990 513 - -

Magnesium (Mg) mg/L 234 154 - -

Sodium (Na) mg/L 890 1,380 - -

Potassium (K) mg/L 26 91 - -

Total Alkalinity (CaCO3) mg/L 650 910 - -

Sulfate (SO4) mg/L 470 1,660 - -

Chloride (CI) mg/L 2,440 1,425 - 250,000 c

Nitrate (as NO3) mg/L 88 22 - -

Fluoride (F) mg/L 0.1 5.0 - -

pH - 7.2-7.4 7.9 - 6.5-8.5 c

Total Dissolved Solids (TDS) mg/L 5,700 6,200 - -

Aluminum µg/L NA 184 - 200 c



TABLE 4.4 RO CONCENTRATE WATER QUALITY EXAMPLES, OCEAN PLAN OBJECTIVES AND FEDERAL DRINKING WATER STANDARDS

Parameter Unit Brackish Water RO Concentrate Water Qualitya

Wastewater RO Concentrate

Water Qualityb

Ocean Plan Water Quality

Objectives

National Drinking Water

Regulations

Antimony µg/L NA 1.0 - 6

Arsenic µg/L NA 3.0 80.0 10

Barium µg/L 660 273 - 2,000

Cadmium µg/L NA 8.1 10.0 5

Chromium (Hexavalent) µg/L NA 10.0 20.0 100

Copper µg/L NA 13.2 30.0 1,300b

Iron µg/L 26 710 - 300 c

Manganese µg/L 8 5 - 50

Mercury µg/L NA 0.12 0.4 2

Nickel µg/L NA 133 50.0 -

Selenium µg/L NA 7.0 150.0 50

Silica mg/L 180 145 - -

Silver µg/L NA 1.0 7 100 c

Nitrite-N µg/L 100 200-500 - 1,000

Cyanide µg/L NA 35 10 -

Ammonia-N µg/L 1,000 75,000-100,000 6,000 -

Notes: a Based on Eastern Municipal Water District Menifee Desalter RO Concentrate Water Quality Projections b Based on OCWD GWRS RO Concentrate Water Quality Projections c Data obtained from National Drinking Water Regulation Sources: California Ocean Plan and National Drinking Water Regulations

According to Table 4-4, with the exception of iron, nickel and ammonia-N, GWRS RO concentrate water quality data fully satisfies Ocean Plan Water Quality Objectives. However, RO concentrate water quality data in Table 4-4 reflect projections in which very conservative assumptions were made (i.e., no removal of metals via microfiltration and 100 percent rejections of metals via RO). Therefore, actual metal concentrations in RO concentrate stream may be lower than the values presented in Table 4-4 and those metals can potentially meet Ocean Plan objectives without further relying on ocean mixing and dilution.



Many coastal wastewater treatment facilities in California were designed and operated for BOD removal only which results in very high concentration of ammonia-N (i.e., >20 mg/L) in ocean outfalls (e.g., City of Oxnard, Orange County outfalls, etc.). Although such ammonia concentration does not satisfy Ocean Plan objectives, ocean discharge can be permitted if adequate dilution and mixing are provided as discussed in Section 4.3.3.

4.3.1 New Ocean Outfall Construction of a new ocean outfall can be complicated due to coastal preserves and endangered or sensitive species located in areas along the coast, such as Marine Protected Areas, coastal preserves, or State Water Quality Management Plans (SWQMP). The best location for an ocean outfall would be in an urban area because impacts to species have already occurred, and the area would likely be disturbed. Figure 4.15 provides a typical ocean outfall configuration.

FIGURE 4.15 TYPICAL OCEAN OUTFALL CONFIGURATION

Source: Calleguas Municipal Water District, 2008

Pipe to be buried 5 feet below the streets Pipe to be laid on the sea floor

for an additional 2,000 feet from shore (past surf zone)

Pipe to be as deep as 50 feet below the sea bed for about 2,000 feet from shore

Diffuser to be laid on the sea floor for an additional 500 feet from shore

Buried Vault



4.3.2 Disposal Costs Capital and O&M costs for ocean outfalls vary based on location (i.e., existing infrastructure conflicts, topography, and population density) whether the outfall is a new or existing facility, stakeholder groups in the area, and environmental issues in the area. To include the new outfall costs, an estimated unit cost value was obtained from Calleguas Municipal Water District (MWD) Salt Management Project (Calleguas Municipal Water District, 2008). Table 4.5 lists the estimated outfall costs.

TABLE 4.5 ESTIMATED OUTFALL COSTS

Outfall L ength (feet)

Outfall Diameter (inc hes )

E s timated C os t ($)

10,000 54 11,000,000

15,000 60 29,000,000

33,000 66 55,000,000

Source: SAWPA, 2004.

Capital requirements for the new brine lines were calculated based on the cost information obtained from the Calleguas MWD Salt Management Project (SMP) Phase I, which is under construction, as well as SARIS system costs. Phase I of the SMP project has a unit price of $16.5 per pipe diameter in inches per linear foot for the pipeline, along with other project costs and permitting. The overall estimated project cost for a new brine line/outfall system was estimated by adding the brine line and ocean outfall cost together.

Connectivity and user fees are project or site specific. For example SAWPA applies the fees summarized in Table 4.6 for brine discharges to the Santa Ana River Interceptor (SARI) System for 2009:

TABLE 4.6 SAWPA RATES FOR TREATMENT AND DISPOSAL OF NON-RECLAIMABLE AND TEMPORARY DOMESTIC WASTEWATER

F is c al Y ear F low/ MG Da

B OD/ 1000 lbs b

T S S / 1000 lbs c

F ixed P iped

F ixed T reatmente

2009-2010 $850 $283 $420 $2,581 $6,452

Notes: a This component shall be calculated and assessed per gallon of discharge (flow) to the SARI System each month. b This component shall be calculated and assessed per gallon of dry weight of BOD calculated from the average of sample results each month. c This component shall be calculated and assessed per gallon of dry weight of TSS calculated from the average of sample results each month. d This component for fixed costs (also known as Readiness to Serve) shall be assessed per MGWD of owned pipeline/connection capacity per month. e This component for fixed costs shall be assessed per MGWD of owned treatment and disposal capacity per month.



Additional fees applied by SAWPA for discharges to the SARI system include:

• An annual permit fee of no less than $500

• Discharge of non-reclaimable wastewater from sources within the Santa Ana River watershed shall be charged truck rates for $0.010 per gallon of brine discharge (less than 100 mg/L of BOD and TSS) or $0.029 per gallon of non-brine discharges (greater than or equal to 100 mg/Lo of BOD and TSS). Discharges from outside the watershed shall be charged $0.14 per gallon of waste.

• A fixed cost of $0.0915 per gallon per month for leases of SARI connection capacity.

The connection fees shown above may be somewhat inflated due to capital cost recovery, so lower connection fees may be expected in some other projects locations. Average connection fees are subject to infrastructure pricing structures of operating agencies.

Conveyance infrastructure required to transport the concentrate to the discharge point is usually comprised of closed pipelines. Design of the conveyance system should address materials of construction, time required for transportation, and pumping costs. The materials used to construct the conveyance system are an important consideration due to the corrosivity of the concentrate resulting from high TDS concentrations. The time required for conveyance of the concentrate to the discharge point is also a key consideration in applications where sparingly soluble salts (such as carbonates, sulfates, and silicates) are supersaturated. Given a sufficient amount of time, precipitation of these salts could occur in the conveyance system resulting in scaling of infrastructure surfaces. The shorter the time concentrate resides in the conveyance system, the smaller the chance sparingly soluble salts will precipitate and cause operational difficulties. Finally, the pumping system is a critical consideration during the design of a concentrate conveyance system. Depending on the energy of the concentrate exiting membrane treatment and the energy requirements for conveyance of the concentrate to the discharge point, a pumping system might be required.

4.3.3 Considerations for Regulatory Approval Construction of a new outfall would require completion of technical and environmental analyses. These studies would serve as the basis for application to obtain construction and operation permits from the State Water Resources Control Board (SWRCB), RWQCB, United States Army Corps of Engineers (USACE), California Coastal Commission (CCC), California Department of Fish and Game (CDFG), United States Fish and Wildlife Service (USFWS), National Marine Service Fisheries—a Division of the Department of Commerce (NOAA Fisheries Service), and local agencies.



For any new outfall or structural changes to an existing outfall, the California Environmental Quality Act (CEQA) process will be initiated, and a USACE Section 404 permit most will likely be required. In addition, Section 7 of the Endangered Species Act will be triggered, requiring consultation from the resource agencies on the CEQA documentation, as well as the NPDES permit. Also, coordination with the State Lands Commission (SLC) could be required for a lease of coastal lands under their ownership, as well as for any stream crossings. For a new outfall to be eligible to receive a permit, from an RWQCB perspective, as well as a California Coastal Commission (CCC) perspective, it must be a sufficient distance from any sensitive areas, including State Water Quality Protection Areas.

Given a satisfactory environmental impact study, a temporary permit could be issued during design and construction of the outfall based on acceptable water quality and quantity, and suitable outfall design. However, the permanent discharge permit generally will not be issued until the full-scale facility has passed rigorous water quality tests to determine constituent concentrations. In addition, the effluent must pass a bioassay test prior to issuance of an ocean discharge permit. Instances have occurred where a permanent permit was not issued for an ocean outfall based on results from the bioassay tests.

Regulatory issues involved with discharging membrane concentrate to surface water primarily involve obtaining an NPDES permit and any permits associated with conveyance to the discharge site. In some cases, individual states have implemented their own NPDES guidelines that must be followed. Requirements for obtaining an NPDES permit include determination of quality and quantity of membrane concentrate. In addition, reporting guidelines to the regulating agency are to be determined prior to issuance of an NPDES permit. An NPDES permit will be issued only if requirements imposed by national and state authorities are satisfied. These requirements are dependent on the body of water being discharged into, as well as secondary treatment standards. Additional information regarding the application process for an NPDES permit is provided in the USEPA NPDES Permit Writers’ Manual (1996).

One key issue associated with obtaining an NPDES permit is the ability to provide an adequate visual mixing zone for the concentrate to protect the marine habitat. At existing refinery and power plant outfalls, updating the NPDES permit might be difficult if the existing outfall does not provide adequate mixing and if existing water quality limits preclude the discharge of non-ocean water sources. Limits on metals are of particular concern as NPDES limits are often below drinking water quality because they are based on the Ocean Plan. For the Calleguas Municipal Water District Salt Management Project new ocean outfall, the RWQCB set a dilution ratio of 72 to 1. This ratio is more than sufficient for compliance with the Ocean Plan objectives.



Qualifications for obtaining a permit to discharge concentrate to an ocean outfall are slightly more stringent. Given a satisfactory environmental impact study, a temporary permit could be issued during design and construction of the treatment facility based on acceptable membrane concentrate quality and quantity, and on suitable outfall design. However, the permanent discharge permit generally will not be issued until the full-scale facility has passed rigorous concentrate quality tests to determine constituent concentrations. The permit application process will require:

• Outfall diffuser modeling • Water quality modeling • Sampling of anticipated flows

The Coastal Zone Management Act (CZMA) requires all federal permittees that affect a state coastal zone to comply with state guidelines regarding coastal zone management. These guidelines could affect any ocean discharge requiring one or more federal permits. The coastal zone includes states adjacent to the Great Lakes, and all East, West, and Gulf Coast states.

4.4 Landfill Disposal Option

4.4.1 Introduction For a majority of the concentrate management alternatives, the end disposal mechanism is disposal of either the liquid/slurry or concentrate-precipitated solid to a landfill. The amount of material disposed of into a landfill depends upon which reduction/disposal alternative is used, as well as its efficacy. Concentrate is designated by USEPA as an industrial waste, which is significant because this designation limits disposal to a Class I landfill.

Class I landfills are facilities that can accept industrial wastes as defined in the California Code of Regulations (23 CCR 2531, Municipal Solid Waste, Construction Debris, and Yard Waste). The designation of concentrate by USEPA as an industrial waste occurred because USEPA has only two waste designation categories—domestic discharge and industrial discharge (everything else). A number of factors must be taken into account when identifying potential disposal sites including:

• Disposal of liquid waste might not be permitted at every facility and could be significantly more expensive because liquid waste is most commonly required to be in drums prior to disposal.

• Landfills have restrictions regarding the acceptance of liquid waste. Some landfills cannot accept any liquid waste. Landfills that accept liquid waste must be lined. For Class III landfills the waste-to-liquid ratio is typically 5:1 or 20 percent moisture content.

• Not all Class I landfills have the same permit requirements, and at this time, most RWQCBs do not allow disposal of materials that have high TDS content.



• High transport and disposal costs are associated with disposing material in landfills. Also, disposal fees can vary dramatically by landfill facility. Transportation fees will vary based on the location and could be costly.

Table 4.7 provides a list of potential industrial waste management facilities in the region.

TABLE 4.7 CALIFORNIA COMMERCIAL OFFSITE INDUSTRIAL WASTE MANAGEMENT FACILITIES

Facility Name Location Type of Waste Streams Permitted

Waste Management Kettleman Hills

Kettleman City Wide range

Clean Harbors Buttonwillow

Buttonwillow Wide range

Clean Harbors Westmoreland

Westmoreland Wide range

Clean Harbors Wilmington

Wilmington Wide range (Wastewater)

Note: This list includes commercial hazardous-waste-permitted recycling, treatment, storage, and disposal facilities that accept offsite waste for a fee and perform treatment and/or disposal at the facility.

4.4.2 Classification of a Waste Concentrate has to be disposed of at a Class I landfill. This class of landfill can take hazardous and nonhazardous wastes. Nonhazardous wastes are defined as:

. . . all putrescible and non-putrescible solid, semi-solid, and liquid wastes including garbage, trash, refuse, paper, rubbish, ashes, industrial wastes, demolition and construction wastes, abandoned vehicles and parts thereof, discarded home and industrial appliances, manure, vegetable or animal solid and semi solid wastes and other discarded waste (whether of solid or semi solid consistency); provided that such wastes do not contain wastes which must be managed as hazardous wastes, or wastes which contain soluble pollutants in concentrations which exceed applicable water quality objectives, or could cause degradation of waters of the state (i.e., designated waste). . .

For hazardous wastes, Title 22 Division 4.5 sets criteria for defining the characteristics of a hazardous waste. The waste designation classification is important because different waste designations incur different disposal fees.



There are two hazardous waste classifications—listed and characteristic. Listed wastes are specific wastes that can be from specific or nonspecific sources. Listed wastes are identified in the California Code of Regulations (CCR) and CFR. Because listed wastes are considered hazardous despite their respective characteristics, dilution does not change a listed waste classification to a hazardous waste; dilution simply creates a larger amount of listed hazardous waste. Because of this characteristic of listed wastes, the concentrate waste discussed in this report is not likely to consist of listed wastes.

A waste is considered a characteristic hazardous waste if it exhibits any one of four characteristics—toxicity, corrosivity, reactivity, or ignitability. Classification of the concentrate is site specific and is based on the waste characteristics. From initial comparisons of brine/concentrate constituents from the West Basin Municipal Water District (MWD) West Basin Barrier Project, brine/concentrate would not appear to be classified as a hazardous waste. However, this classification will be site specific and dependent upon the discharges to the wastewater or recycled water treatment plant and will need to be determined on a case-by-case basis. For this reason, each of these waste characteristics is described in detail below.

Toxicity The toxicity characteristic is determined by a series of analytical tests. If the waste will be disposed of in California, the CCR applies, and total threshold-limit concentrations (TTLC) and soluble threshold-limit concentrations (STLC) are used to determine if a waste has the toxicity characteristic. If the waste will be disposed of outside California, the CFR applies, and the TTLC and the toxicity characteristic leaching procedure (TCLP) are used to determine if a waste has the toxicity characteristic. Figure 4.16 is a process flow diagram of how to determine if a waste has a toxicity characteristic.

The TTLC test is performed first. If the results of the TTLC test are less than 10 times the TTLC or 20 times the TCLP limits, the waste does not exhibit the toxicity characteristic. If the results exceed 10 times the TTLC or 20 times the TCLP limits, the STLC or the TCLP test is performed. If the results of the STLC or the TCLP test exceed their respective limits, the waste is considered hazardous per the toxicity characteristic. Based on current concentrations provided by the West Basin MWD West Basin Barrier Project and accounting for brine/concentrate concentration related to the technologies discussed in this report, the brine/concentrate is not expected to be classified as hazardous based on the toxicity characteristic (see the determination process in Figure 4.16 and the information in Table 4.8 from the West Basin MWD).



FIGURE 4.16 FLOW PROCESS DIAGRAM FOR TOXICITY CHARACTERISTIC

PERFORM THE TTLC TEST

PERFORM THE STLC TEST

PERFORM THE TCLP TEST

YES

NO

WASTE DOES NOT EXHIBIT THE TOXICITY

CHARACTERISTIC

YES

NO

YES WASTE IS HAZARDOUS BASED ON THE

TOXICITY CHARACTERISTIC.

YES

NO

YES

WASTE DOES NOT EXHIBIT THE TOXICITY

CHARACTERISTIC.

NO

WILL THE WASTE BE DISPOSED OF IN A LANDFILL? IN CALIFORNIA?

ARE THE RESULTS OF THE TTLC TEST

<20 TIMES THE TCLP LIMITS?

ARE THE RESULTS OF THE TTLC TEST <10X THE STLCS?

ARE THE RESULTS OF THE STLC TEST >

THE STLCs?

ARE THE RESULTS OF THE TCLP TEST >

THE TCLP LIMITS?



TABLE 4.8 SUMMARY OF WEST BASIN MUNICIPAL WATER DISTRICT BARRIER PROJECT BRINE CONCENTRATIONS

Constituent Units TCLP Limita STLC TTLC

Maximum Concentration

2000 2001 2002 2003 2004

pH 6.8 7 7.1 7.5 7.2

Arsenic µg/L 5,000 5,000 500,000 14.9 28.8 30 36.5 31

Antimony µg/L - 15,000 500,000 6.57 5.77 6.37 6.8 6.68

Beryllium µg/L - 750 75,000 <1 0.1 0.1 0.14 0.2

Cadmium µg/L 1,000 1,000 100,000 <1 5.6 0.95 1.47 1.12

Chromium III µg/L 5,000 250,000 45 29 47.2 95 87

Chromium IV µg/L - 5,000 500,000 <5 0.25 2.9 1.5 1.4

Total Chromium µg/L 5,000 5,000 2,500,000 44.9 51.7 87.1 111 122

Copper µg/L - 25,000 2,500,000 158 95 45.2 51.5 98.4

Lead µg/L 5,000 5,000 1,000,000 34.2 19 2.1 1.52 1.33

Mercury µg/L 200 200 20,000 1.27 1.31 1.24 1.09 1.12

Nickel µg/L - 20,000 2,000,000 123 96 78 99.9 59.3

Selenium µg/L 1,000 1,000 100,000 23.2 23 22.8 38.3 32.4

Silver µg/L 5,000 5,000 500,000 <5 2.1 1.66 2.27 2.96

Thallium µg/L - 7,000 700,000 <1 <0.11 - <0.18 <0.18

Zinc µg/L - 250,000 5,000,000 144 160 90.6 123 249

Lindane µg/L 400 400 4,000 0.04 <0.063 <0.063 <0.063 <0.063

Endrin µg/L 20 20 200 0.05 <0.031 <0.031 <0.031 <0.031

Heptachlor µg/L 8b 470 4,700 <0.01 <0.03 <0.03 <0.03 <0.03

Heptachlor Epoxide µg/L 8b - - - <0.03 <0.03 <0.03 <0.03

Total PCBs µg/L - 5,000 50,000 0.25 - - - -

1,1-Dichloroethene µg/L 700 - - <1 <0.32 <0.32 <0.32 <0.32

1,2-Dichloroethane µg/L 500 - - <1 <0.35 <0.35 <0.35 <0.35

1,4-Dichlorobenzene µg/L 7,500 - - 3 9.7 12 10.5 9.9

Benzene µg/L 500 - - <1 <0.09 <0.09 <0.09 <0.09

Trichloromethane µg/L 6,000 - - 13 25 30 33 29

Carbon Tetrachloride µg/L 500 - - <1 <0.29 <0.29 <0.29 <0.29

Chlorobenzene µg/L 100,000 - - <1 <0.14 <0.14 <0.14 <0.14

Tetrachloroethene µg/L 700 - - 10 7.8 12 14 33

Trichloroethene µg/L 500 20,400 204,000 <1 0.46 <0.26 0.5 1.2



TABLE 4.8 SUMMARY OF WEST BASIN MUNICIPAL WATER DISTRICT BARRIER PROJECT BRINE CONCENTRATIONS

Constituent Units TCLP Limita STLC TTLC

Maximum Concentration

2000 2001 2002 2003 2004

Vinyl Chloride µg/L 200 - - <5 <0.24 <0.24 <0.24 <0.24

2,4,6-Trichlorophenol µg/L 2,000 - - <1 <2.2 <2.2 1.9 1.3

2,4-Dinitrotoluene µg/L 130 - - <1 <2.2 <2.2 <0.4 <0.4

Hexachlorobutadiene µg/L 500 - - <1 <1.2 <1.2 <0.48 <0.48

Hexachloroethane µg/L 3,000 - - <1 - - - <0.51

Nitrobenzene µg/L 2,000 - - <1 <1.3 <1.3 <0.46 <0.46

Note: aTCLP limits apply where California-specific concentration limits are not identified. bConcentration limit applies to the total concentration of heptachlor and its epoxide. < Indicates that the parameter was not detected and the given value is the method detection limit. - Indicates that the parameter was not analyzed.

Corrosivity The corrosivity characteristic generally is determined by a pH less than 2 or greater than 12.5. Based on the pH data of concentrate provided from the West Basin MWD West Basin Barrier Project, the pH of the concentrate is expected to be between 2 and 12.5. Therefore, the concentrate is not expected to be classified as hazardous waste based on the corrosivity characteristic.

Reactivity The reactivity characteristic generally applies to wastes that are unstable, react violently, create explosive mixtures, or generate toxic gases or fumes when mixed with water, or are capable of detonation. Based on the aqueous and stable nature of the concentrate, the concentrate is not expected to be classified as hazardous due to a reactivity characteristic.

Ignitability The ignitability characteristic generally applies to wastes with flashpoints less than 60°C. Because concentrate does not exhibit the ignitability characteristic and the concentration processes discussed in this report are not expected to increase the ignitability of the concentrate, the concentrate is not expected to exhibit the ignitability characteristic. Therefore, the brine concentrate is not expected to be classified as hazardous waste based on the ignitability characteristic.

O&M costs for landfill depend on waste quality and the type of landfill to be utilized. The disposal costs in Los Angeles area vary between $50 and $150 per dry ton disposed. Another cost factor is the hauling and annual permit fees.


5 Energy Generation and Recovery

5.1 Energy Generation and Recovery from Brine Concentrate

Most of the brine-concentrate technologies require a significant amount of energy to operate to overcome thermodynamic barriers such as boiling point rise, heat of dilution and parasitic energy losses and inefficiencies. In general there are few opportunities to generate or recover power in these processes. Two types of energy recovery concepts are currently employed in specific situations to help reduce the power demand on some technologies.

The first concept is sometimes used with systems treating high TDS feed water, especially seawater systems employing a second pass RO unit to further purify permeate from the primary RO system. In such cases, a turbine or turbocharger can be used to recover energy from the primary RO high pressure reject stream to help drive the second RO system. This typically works best when the brine-concentrate has a TDS between 10,000 and 40,000 mg/L, where recovery is relatively low and the pressurized reject stream has a significant amount of recoverable potential energy. Marginal recovery rates can also occur when TDS levels are between 5,000 and 10,000 mg/L or between 50,000 and 70,000 mg/L, on a site-specific basis.

The second concept is to utilize the waste heat from one process to generate energy or steam to power another process unit(s). This has been done in wastewater digesters and membrane distillation processes; however, whether such technology can be economically employed on brine-concentration technologies is unknown.

5.2 Co-Siting of Facilities

Co-siting of facilities has two primary potential advantages—cost savings due to reduced or eliminated utility conveyance and reduced environmental impacts. Power and water conveyance are the typical utilities that benefit the most from co-siting facilities. Savings are realized as a result of lower capital costs for conveyance facilities and from improved energy efficiencies resulting from shorter conveyance distances. An example of this arrangement includes power plants that are located near large power users, such as a brine-concentrate system and multiple discharges located adjacent an outfall system. Co-siting of brine-concentrate generating facilities and disposal facilities such as a wastewater treatment plant, brineline, or outfall could reduce costs and maximize collateral efficiencies. Facilities that can share outfall capacities can also reduce capital and operation costs if they are optimized to work integrated. Co-siting could also reduce the overall footprint of the facilities if the site plan designs are integrated. Careful site layout and visual barriers



that combine aesthetic and noise abatement functions have been adopted in some desalination projects that are located in urban areas.

For some brine-concentrate projects, renewable energy facilities such as solar power can be included as part the overall facility. In many cases, these power sources might not be as cost-effective as traditional power sources. However, in more remote areas, such power options could be more attractive because of the reduced population density and lower land costs. For solar evaporation or brine ponds that are often located away from urbanized areas and in sunnier climates, co-siting of solar power units could be attractive.


6 Summary of Technologies Figure 6.1 presents a summary of the brine-concentrate treatment technologies and disposal options. In addition, a general assessment of their applicability to wastewater and groundwater sources is summarized in the figure. The relative performance of the treatment and disposal options is rated based on the evaluation criteria discussed in the above sections. These criteria were used to summarize the advantages and disadvantages associated with each technology.

LEGEND

Good Average Poor NA - Not Applicable Unk. - Unknown

FIGURE 6.1 SUMMARY OF BRINE-CONCENTRATE TECHNOLOGY APPLICABILITY AND EVALUATION CRITERIA

Applicability Evaluation Criteria

Technology Illustration

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VOLUME REDUCTION TECHNOLOGIES Electrodialysis (ED) / Electrodialysis Reversal (EDR)

Vibratory Shear-Enhanced Processing (VSEP)

Precipitative Softening and Reverse Osmosis (PS/RO)

Enhanced Membrane Systems (EMS)

Mechanical and Thermal Evaporation (MTE)

MembraneReject

ProductWater

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BrineConcentrate to

Evaporator/Crystallizer

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Constructed Wetlands (CW)

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VOLUME REDUCTION TECHNOLOGIES Forward Osmosis (FO)

Unk. Unk. Unk. Unk. Unk. Unk. Unk. Unk. Unk. Unk. Unk. Unk. Unk. Unk. Unk.

Membrane Distillation (MD)

Natural Treatment Systems (NTS)

Slurry Precipitation and Reverse Osmosis (SPARRO)

Advanced Reject Recovery of Water (ARROW)

Capacitive Deionization (CDI)

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ZERO LIQUID DISCHARGE Combination Thermal Process with Zero Liquid Discharge (ZLD)

Enhanced Membrane and Thermal System ZLD

Evaporation Ponds (EP)

Wind-Aided Intensified Evaporation (WAIV)

Dewvaporation

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FINAL DISPOSAL OPTIONS Deep Well Injection (DWI)

NA NA

WWTP Effluent Blending

NA NA NA

Ocean Outfall

NA NA NA

Landfill

NA NA

Technology_Report.doc

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American Water Works Association (AWWA). 2004. Committee Report: Current Perspectives on Residuals Management for Desalting Membranes. Prepared by AWWA Membrane Residuals Management Subcommittee. Proceedings AWWA Membrane Technology Conference, Phoenix, AZ.

Aquatech. 2009. http://www.aquatech.com/casestudies.php.

Ayers, R.S. and D.W. Wescott. 1985. Water quality for agriculture. FAO Irrigation and Drainage Paper 29. Rome.

Big Bear Area Regional Wastewater Agency (BBARWA). 2006. VSEP Pilot Testing; Concentrate Management Study. April.

Calleguas Municipal Water District. 2008. Calleguas Regional Salinity Management Project – Channel Counties Water Utilities Association. PowerPoint Presentation. February.

Child, S.E. 2005. Productive Use of Low Quality Saline Water: Challenges and Opportunities in the Middle East. In Proceedings of the International Salinity Forum: Managing Saline Soils and Water.

City of Laguna Niguel Public Works Department. 2004. Final Report Wetlands Capture and Treatment (WETCAT) Network – Agreement No. 01-122-259-0. Prepared for San Diego Regional Water Quality Control Board.

City of Oxnard. 2003. Additional Testing for the Membrane Concentrate Pilot Wetlands Project Report.

City of Oxnard. 2004. Membrane Concentrate Pilot Wetland Project Report.

City of Santa Maria. 2008. Evaluation of Concentrate Disposal Options.

Daniel Fuster Salamero. 2004. Modeling of Membrane Distillation Processes. Computer Aided Process Engineering Center, Department of Chemical Engineering, Technical University of Denmark, Denmark.

Elimelech Lab. 2009. http://www.yale.edu/env/elimelech/Photos_Page/Photos_Page.html.

GE Water and Process Technologies. 2009. http://www.gewater.com/what_we_do/water_scarcity/water_reuse.jsp.

Gilron J., Folkman Y., Savliev R., Waisman M., and Kedem O. 2003. WAIV – Wind Aided Intensified Evaporation for Reduction of Desalination Brine Volume.



GJG Juby and CF Schutte. 2000. Membrane Life in a Seeded-Slurry Reverse Osmosis System. Water SA Vol. 26 No. 2 April.

Glenn, E.P. and J.J. Brown. 1999. Salt Tolerance and Crop Potential of Halophytes. Critical Reviews in Plant Sciences 18(2):227-255.

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Attachment A Halophyte Land Requirements

Irrigation Water Requirements Calculator - Irvine, California

MonthETo (in)

Kc[-]

P (in)

Etc(in)

Peff (in)

NIWR Halophyte

(in)

GIWR w/o LF

(in)

GIWR w/ LF (in)

Jan 2.294 0.000 2.15 0.00 0.00 0.00 0.00 0.00Feb 2.418 0.005 3.44 0.01 0.01 0.00 0.00 0.00Mar 3.755 0.032 1.61 0.12 0.12 0.00 0.00 0.00Apr 4.737 0.147 0.87 0.70 0.51 0.19 0.22 0.22May 5.372 0.423 0.30 2.27 0.16 2.11 2.48 2.48Jun 5.589 0.766 0.08 4.28 0.00 4.28 5.04 5.04Jul 6.489 0.872 0.03 5.66 0.00 5.66 6.66 6.66Aug 6.199 0.619 0.01 3.84 0.00 3.84 4.51 4.51Sep 4.752 0.276 0.29 1.31 0.15 1.17 1.37 1.37Oct 3.602 0.078 0.80 0.28 0.28 0.00 0.00 0.00Nov 2.511 0.014 1.05 0.04 0.04 0.00 0.00 0.00Dec 2.137 0.002 1.89 0.00 0.00 0.00 0.00 0.00Total 49.86 12.53 18.51 1.27 17.24 20.28 20.28

Vegetation Type

Irrigated Area

(acres) Annual Irrigation Demand663 1,121 ac-ft

365 MGNormal Depth of Soil Moisture Depletion (in) 2.28 1.000444 MGD

LF 0%Total Leaching Requirement (in) 0.00

Combined Irrigation Efficiency 85%

Notes and Definitions:Kc - crop coefficientETo - reference grass evapotranspirationETc - crop evapotranspiration (ETo x Kc halophyte)P - average precipitationPeff - effective precipitation (calculated using SCS method w/ monthly P, ETc, and effective soil water storage)NIWR - net irrigation water requirements (ETc - Peff)GIWR w/o LF - gross irrigation water requirements without leaching fraction (NIWR / (combined irrigation efficiency) )LF - leaching fraction (assumed no leaching fraction)Total Leaching Requirement = GIWR w/ LF - GIWR w/o LFGIWR w/ LF = GIWR w/o LF / (1 - LF)Normal Depth of Soil Moisture Depletion is 50% of AWHC over the rooting zone depth; assumed for Sorrento soils with 0.19 in/in available water and a 24-inch rooting depth

Saltgrass

Irrigation Water Requirements Calculator - Riverside, California

MonthETo (in)

Kc[-]

P (in)

Etc(in)

Peff (in)

NIWR Halophytes

(in)

GIWR w/o LF

(in)

GIWR w/ LF (in)

Jan 2.49 0.000 2.05 0.00 0.00 0.00 0.00 0.00Feb 2.72 0.005 2.48 0.01 0.01 0.00 0.00 0.00Mar 4.35 0.032 1.18 0.14 0.14 0.00 0.00 0.00Apr 5.33 0.147 0.59 0.78 0.29 0.49 0.58 0.58May 6.19 0.423 0.20 2.62 0.07 2.55 3.00 3.00Jun 6.65 0.766 0.09 5.09 0.00 5.09 5.99 5.99Jul 7.53 0.872 0.02 6.56 0.00 6.56 7.72 7.72Aug 7.19 0.619 0.02 4.45 0.00 4.45 5.24 5.24Sep 5.49 0.276 0.22 1.52 0.08 1.44 1.69 1.69Oct 4.00 0.078 0.49 0.31 0.23 0.08 0.10 0.10Nov 2.82 0.014 0.63 0.04 0.04 0.00 0.00 0.00Dec 2.39 0.002 0.77 0.00 0.00 0.00 0.00 0.00Total 57.14 8.74 21.54 0.87 20.67 24.32 24.32

Vegetation Type

Irrigated Area

(acres) Annual Irrigation Demand553 1,121 ac-ft

365 MGNormal Depth of Soil Moisture Depletion (in) 1.2 1.0003954 MGD

LF 0%Total Leaching Requirement (in) 0.00

Combined Irrigation Efficiency 85%

Notes and Definitions:Kc - crop coefficientETo - reference grass evapotranspirationETc - crop evapotranspiration (ETo x Kc halophyte)P - average precipitationPeff - effective precipitation (calculated using SCS method w/ monthly P, ETc, and effective soil water storage)NIWR - net irrigation water requirements (ETc - Peff)GIWR w/o LF - gross irrigation water requirements without leaching fraction (NIWR / (combined irrigation efficiency) )LF - leaching fraction (assumed no leaching fraction)Total Leaching Requirement = GIWR w/ LF - GIWR w/o LFGIWR w/ LF = GIWR w/o LF / (1 - LF)Normal Depth of Soil Moisture Depletion is 50% of AWHC over the rooting zone depth; assumed for Willows soils with 0.10 in/in available water and plant rooting depth of 24 inches

Saltgrass

Brine-Concentrate Treatment and Disposal Options Report

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