ELECTRODIALYSIS REVERSAL (EDR) TREATMENT AT FORT IRWIN Jason Yoshimura, PE, BCEE; CDM Smith, 1925 Palomar Oaks Way, Suite 300, Carlsbad, CA 92008; yoshimurajt@cdmsmith.com; 760-438-7755 William K. O Neil, CDM Smith, Carlsbad, CA Dr. Donald Thompson, CDM Smith, Jacksonville, FL ABSTRACT Fort Irwin National Training Center (Ft Irwin) is located in the Mojave Desert in California and serves as a major combat training center for the United States military. Ft Irwin uses a groundwater supply that exceeds the maximum contaminant levels (MCL) for fluoride and arsenic. demands average between 2.0 and 2.5 million gallons per day (mgd) and range from 0.8 mgd to 5.3 mgd, depending on troop rotation and season. Ft Irwin currently operates two separate water distribution systems. Potable water for drinking is produced by treating the groundwater with reverse osmosis (RO) and distributing it through the RO distribution system. Untreated groundwater is distributed through the domestic water (DO) distribution system for other uses. However, the California Division of Drinking (DDW) has determined that the water delivered via the DO distribution system must meet all applicable drinking water standards. To meet these requirements, Ft Irwin has constructed a new water treatment plant, the Irwin Works (IWW) that will produce up to 6.0 mgd of potable water, as well as combine the two existing distribution systems to provide a single potable water system. Due to high silica concentrations, the current RO treatment process operates at a low recovery rate. Pilot testing was performed to select a more efficient treatment process. This resulted in the selection of electrodialysis reversal (EDR) as the primary treatment process for the new IWW. The EDR process was shown to effectively meet treatment goals while providing a higher recovery rate than RO. GE s projections indicated that the EDR system could achieve a recovery of 92 percent. The overall recovery rate will be increased to greater than 99 percent by providing additional treatment for the EDR concentrate. The final residuals will be discharged to on-site drying beds, resulting in a zero liquid discharge facility. EDR is a membrane process that utilizes electricity to drive the separation of ions from the source water stream. EDR utilizes a stack of alternating anion and cation exchange membranes with electrodes, one operating as an anode and one operating as a cathode, located on either ends of the stack. The alternating anion/cation exchange membrane configuration results in alternating dilute and concentrate streams. The new EDR system will allow Ft Irwin to produce potable water that meets all applicable drinking water standards and meet all water demands. In conjunction with the waste stream treatment process, the IWW will produce water with a recovery of greater than 99 percent, while 1
discharging no liquid waste. The IWW will allow Ft Irwin to meet its goals of producing high quality drinking water while conserving their limited resources to provide a reliable water source for the Base and its personnel for many years to come. This paper will provide an overview of the EDR process and describe the initial steps of startup of the system at the IWW. BACKGROUND 1 Fort Irwin National Training Center (Ft Irwin) is located in the Mojave Desert in the State California and serves as a major combat training center for the United States military. Ft Irwin's water is supplied by ten groundwater wells, located in three different groundwater basins Irwin, Bicycle Lake, and Langford. The groundwater from these basins has high concentrations of fluoride, arsenic, and silica, and moderate concentrations of total dissolved solids (TDS). Blended water from the three basins typically exceeds the maximum contaminant levels (MCL) for fluoride and arsenic. Depending on the basin, average fluoride concentrations range from 2.3 mg/l to 9.4 mg/l (MCL is 1.0 mg/l) and average arsenic concentrations range from 0.010 to 0.037 mg/l (MCL is 0.010 mg/l). The maximum blended water TDS is less than 1,000 milligrams per liter (mg/l) and silica concentrations range from 70 to 95 mg/l. One basin also produces groundwater with elevated nitrate concentrations. demands average between 2.0 and 2.5 million gallons per day (mgd) and range from 0.8 mgd to 5.3 mgd, depending on troop rotation and seasonal irrigation requirements. Ft Irwin currently operates two separate water distribution systems. Potable water for drinking is produced by treating the groundwater with a 0.15 mgd single pass reverse osmosis (RO) system and distributing it through the RO distribution system. Untreated groundwater is distributed through the domestic water (DO) distribution system for other uses such as irrigation, showering, laundry, and toilet flushing. The DO system groundwater is chlorinated and tested similar to a potable water distribution system relative to total coliform and chlorine residual monitoring. In 2004, the California Department of Public Health (CDPH) [now the Division of Drinking (DDW)] issued a Domestic Supply Permit for the Fort Irwin System along with a supporting Engineering Report. 2 At that time, CDPH determined that the operation of a dual plumbing system was not compliant with Works Standards, and requested that the United States Department of the Army submit by July 31, 2004, a plan and time schedule needed to eliminate the use of a dual water system and provide water to all of the domestic system outlets that is in compliance with all Drinking Standards. The 2004 CDPH Engineering Report also noted arsenic had been detected in all of the groundwater wells and proper treatment will be needed to comply with the new arsenic standard. To improve the current drinking water system to meet these requirements, Ft Irwin is constructing a new water treatment plant, the Irwin Works (IWW), which will produce up to 6.0 mgd of potable water, and constructing improvements to combine the existing RO and DO distribution systems to provide a single potable water system. 2
In 2006, the United States Environmental Protection Agency (USEPA) established a maximum contaminant level (MCL) of 10 micrograms per liter (µg/l) for arsenic. Arsenic is odorless and tasteless and enters drinking water supplies from natural deposits in the earth or from agricultural and industrial practices. The arsenic present in Ft Irwin s groundwater was determined to be naturally occurring. Non-cancer effects of chronic arsenic exposure can include thickening and discoloration of the skin, stomach pain, nausea, vomiting, diarrhea, numbness in hands and feet, partial paralysis, and blindness. Arsenic has been linked to cancer of the bladder, lungs, skin, kidney, nasal passages, liver, and prostate. USEPA required compliance with the standard by January 23, 2006. 3,4 Fluoride is also a naturally occurring contaminant in Ft Irwin s groundwater. The USEPA set a fluoride MCL of 4 mg/l in 1986. 3 Effects of excessive consumption of fluoride over a lifetime may lead to increased likelihood of bone fractures in adults, and may result in pain and tenderness in the bones. Children aged 8 years and younger exposed to excessive amounts of fluoride have an increased chance of developing pits in the tooth enamel, along with a range of cosmetic impacts on the teeth. USEPA also set a secondary standard of 2 mg/l for fluoride. The secondary standard was set, as a guideline, to reduce the potential of adverse cosmetic impacts from fluoride. 5 The State of California has chosen to adopt the more stringent fluoride MCL of 2 mg/l as a requirement versus a guideline. 5 Due to moderately high silica concentrations, the existing RO treatment process operates at a relatively low recovery rate (50 to 55 percent). Pilot testing was performed to select a more efficient treatment process that could provide the desired capacity with minimal loss of water. A 2007 pilot study 7, 8 identified electrodialysis reversal (EDR) as the preferred main treatment process for the new IWW. EDR was piloted over an 8 month period along with activated alumina, regenerable (AAR). Over a consecutive 75 day test period, EDR was found to reduce arsenic and fluoride to levels meeting the treated water goals, with minimal pretreatment, operator attention, and at high recovery of 75 percent. EDR was also robust in treating water artificially spiked to represent potential future deteriorated source water quality. In addition, TDS levels were reduced to below 500 mg/l with the EDR process. 7, 8 Although AAR is effective in removal of arsenic and fluoride, it was noted in the pilot study that fluoride removal performance was adversely impacted by the high silica levels and would have required frequent regeneration and additional pretreatment. It was also concluded that the AAR process would be more operationally intensive than EDR. 7, 8 GE was preselected as the EDR manufacturer to supply the EDR system for the new IWW. Using GE s proprietary EDR performance projection software (WATSYS), GE determined that the EDR process would achieve a minimum of 92 percent recovery for the source water quality conditions tested. The 2007 pilot study concluded that the EDR process demonstrated the ability to reduce fluoride and arsenic levels to below the California MCLs and the Fort Irwin drinking water quality goals. The results also indicated the EDR process provided a robust technique for treating groundwater from each of the basins, either individually or as blends from the basins. 3
The results also showed that EDR technology was well-suited for removing higher concentrations of contaminants from the source water if the quality deteriorates in the future. 7, 8 The new treatment facility s overall recovery rate will be further increased to greater than 99 percent by treating the EDR concentrate with a waste treatment recovery system consisting of lime-soda ash softening, microfiltration, three-pass RO, ion exchange softening, and mechanical evaporation. The final residuals will be discharged to on-site drying beds, resulting in a zero liquid discharge facility. Design of the new treatment facility was completed in July 2013 with construction completed in 2015. This paper will provide an overview of the EDR process and the initial steps for startup of the EDR system at the IWW. OVERVIEW OF THE EDR PROCESS 9 EDR is a membrane process that utilizes electricity to drive the separation of ions from the feed water stream. EDR utilizes a stack of alternating water impermeable anion and cation exchange membranes with electrodes, one operating as an anode and one operating as a cathode, located at the top and bottom of the stack. A direct current (DC) potential is applied across the electrodes, which causes the anions in the solution to be drawn towards the anode and cations to be drawn towards the cathode. Figure 1 illustrates an electrode pair immersed in a sodium chloride solution with a DC potential applied to the electrodes. Figure 1 Sodium Chloride Solution Under DC Potential Inside the EDR membrane stack, the anion exchange membranes allow the passage of anions, while blocking the passage of cations. Similarly, the cation exchange membranes allow the passage of cations, while blocking the passage of anions. The alternating anion/cation exchange membrane configuration results in the creation of alternating dilute and concentrate streams within the stack. Figure 2 illustrates the alternating anion/cation membranes in the membrane stack. In the illustration, streams 2 and 4 are the dilute streams and streams 1 and 3 are the concentrate streams. EDR periodically reverses the polarity, thus reversing the dilute and 4
concentrate streams. This process is described in further detail in the EDR Operation section below. Figure 2 Alternating Anion/Cation Exchange Membranes EDR Ion Exchange Membranes EDR membranes are water impermeable polymer membranes with embedded ion exchange resins. Anions are attached to the positively charged ion exchange sites in the anion membrane while cations are repelled. Cations are attached to the negatively charged ion exchange sites in the cation membrane while anions are repelled. The ions attached to the exchange sites within the membrane are known as mobile counter ions. The ion exchange membranes allow the mobile counter ions to move through the membrane while rejecting oppositely charged ions. Figure 3 illustrates the ion exchange resins used in the membranes. Figure 3 Anion/Cation Exchange Resins EDR Membrane Stack The cell pair is the basic building block of the membrane stack. A cell pair consists of an anion membrane, a concentrate spacer, a cation membrane, and a dilute spacer. The cell pairs are stacked to create multiple dilute and concentrate compartments. 5
A standard membrane stack includes 600 cell pairs and provides a treatment capacity of 120 to 150 gallons per minute (gpm). A single membrane stack provides 50 percent removal of TDS. Membrane stacks can be configured in series to provide a multi-stage system that removes up to 94 percent of TDS (using a four stage system). The Ft Irwin EDR system will be a three-stage system, providing 87.5 percent removal of TDS. Figure 4 illustrates a multi-stage EDR configuration. Figure 4 Multi-Stage EDR System EDR Units EDR systems are typically arranged into units that consist of multiple lines of stacks, configured in pairs. Each line can contain one to four membrane stacks in series. Each pair of lines is served by a reversal module and an outlet module. An EDR unit with 8 lines provides a treatment capacity of 1.5 mgd. Figure 5 illustrates a three-stage EDR unit with 8 lines. Figure 5 EDR Unit (3 Stages, 8 Lines) 6
Figure 6 shows a line of EDR membrane stacks with the covers removed on the first two stages. Figure 7 shows the reversal modules for one EDR train. Figure 8 shows the reversal modules for several EDR trains. Figure 6 Line of EDR Stacks (Stages 1 and 2 Uncovered) Figure 7 EDR Reversal Modules 7
Figure 8 EDR Outlet Modules EDR in Drinking Treatment Typical applications for EDR in drinking water treatment include: TDS reduction (3,000 mg/l or less) Specific ion reduction: arsenic, nitrate, perchlorate, radium High fouling water (due to high silica concentrations) Typical recovery for EDR systems treating drinking water is 85 percent without chemical addition, and can be as high as 94 percent with chemical addition. Similar to other membrane treatment systems, EDR membranes have limitations on concentrations of certain contaminants in the feed water to prevent fouling or damage to the membranes. Feed water limitations are summarized below: Iron (dissolved): 0.3 mg/l Manganese (dissolved): 0.1 mg/l Hydrogen Sulfide (H2S): 0.1 mg/l Aluminum: 0.1 mg/l Chemical Oxygen Demand (COD): 50 mg/l as O2 Total Organic Carbon (TOC): 15 mg/l Oil: 2.0 mg/l (IR Method) Allowable levels of other constituents include: 8
Free chlorine: 0.5 mg/l continuous, 30 mg/l intermittent (membrane cleaning) Turbidity: 0.5 NTU continuous, 2.0 NTU intermittent Silt Density Index (SDI5): 10 12 continuous, 15 intermittent EDR System Operation The following section describes the operation of typical EDR systems. Figure 9 provides an EDR system schematic. A description of the various aspects of the system follows. Figure 9 EDR System Schematic Under normal operation, feed water enters through the inlet reversal valve, is treated by the membrane stack (or stacks in a multi-stage system), and final product is discharged through the outlet reversal valve and the product water valve. Brine is recycled back through the concentrate side to prevent large differential pressure across the membranes. Because the concentrate flow is much lower than the feed flow, feed water is added to the concentrate to increase the flow rate through the concentrate side. Some of the concentrate is continuously bled off through the concentrate blow down valve and sent to waste. Polarity reversal occurs 3 to 4 times per hour. Reversing the dilute and concentrate streams reduces scaling on the electrodes and helps to remove organics from the membrane surfaces. Upon polarity reversal, the valves on the reversal and outlet modules are re-positioned to reverse the feed and concentrate feed streams and the product and concentrate return streams. Figure 10 illustrates the process of polarity reversal. 9
Polarity Reversal Figure 10 Polarity Reversal After a polarity reversal occurs, the product will temporarily be high in TDS as the concentrate is flushed out of the dilute compartments. This off-spec product is diverted to waste through the off-spec product (OSP) valve on the outlet reversal module until the conductivity returns to the desired value. In multi-stage systems, off-spec product waste volume can be minimized by initiating polarity reversal in stages, which limits the off-spec product to the volume contained within one membrane stack. Figure 11 illustrates staged polarity reversal for a three stage system. 10
Figure 11 Staged Polarity Reversal Scale Control If the EDR concentrate has a Langelier Saturation Index (LSI) up to 2.1 and the calcium sulfate (CaSO4) concentration is up to150 percent of its saturation limit, polarity reversal alone is typically adequate to control scaling on the membranes. If the EDR concentrate has an LSI greater than 2.1 and the CaSO4 concentration is greater than 150 percent of its saturation limit, polarity reversal should be supplemented with chemical addition to the concentrate stream. When acid is used for scale control in EDR systems, it is added to the concentrate stream, not the feed stream. Thus, no carbon dioxide is formed, so the product water does not require decarbonation. EDR System Cleaning Scale control measures reduce the amount of scale formed on the membranes and electrodes but does not eliminate it completely. EDR systems require periodic cleaning to remove scale buildup. An EDR membrane Clean-in-Place (CIP) is typically performed after every 1,000 rectified operating hours. Similar to other membrane systems, the CIP cleaning solution is batched in a CIP tank and then circulated through the membrane stacks. Heating of the solution is not required. The spent cleaning solution is typically neutralized in the CIP tank and discharged to waste. At the IWW, the spent cleaning solution is sent to the LSLPS without neutralization. Cleaning solution in the membrane stacks is flushed to waste through the OSP valve with feed water. An Electrode Clean-in-Place (ECIP) is typically performed once a month. To perform an ECIP, acid is dosed into the electrode compartment to remove scale from the electrodes. ECIP is typically done automatically. 11
Physical cleaning of the membranes is performed from once a year to several times a year, depending on the composition of the feed water (systems treating wastewater will typically require more cleaning than systems treating drinking water). The membranes are removed from the stacks and manually cleaned with a brush. The membranes must be re-installed into the stack in the same order. Other Considerations To prevent damage to the membranes from solids, 10-micron cartridge filters are commonly installed upstream of EDR systems. In some cases, other pre-treatment may be required to meet feed water quality requirements, such as coagulation/flocculation (polymer can be used), media filtration, or micro/ultrafiltration. EDR product is similar to RO permeate and typically requires stabilization by adding alkalinity and adjusting the ph to achieve a positive LSI. IRWIN WATER WORKS The following discusses the application of the EDR process at the new IWW. Quality The primary source water constituents of concern include arsenic, fluoride, TDS, ph, and Total nitrite/nitrate. Table 1 provides a summary of projected source water quality as well as the drinking water standards and goals established for the IWW. Table 1 Target Source Constituents - Projected Quality, Standards and Goals Constituent Unit Projected Source Quality Federal MCL California MCL Fort Irwin Drinking Quality Goal Arsenic (As) µg/l 40 10 10 7.5 Fluoride (F) mg/l 6 4 (2 b ) 2 1.6 Iron (Fe) mg/l 0.675 0.3 b 0.3 b 0.225 Total Dissolved Solids (TDS) mg/l 700 500-1,000 a 500-1,000 a 500 1,000 ph unit 6.5 to 8.5 b 7 to 8 Total Nitrate & Nitrite mg/l as N 6 10 10 7.5 a Secondary MCL: Recommended 500 mg/l; Upper Range 1000 mg/l; Short term 1500 mg/l b Secondary MCL Table 2 presents the typical range in water quality historically detected in the groundwater sources. All sources have fluoride levels above the drinking water standard (2 mg/l), and are generally above the arsenic standard (10 µg/l). The lowest fluoride levels are noted in wells 12
drawing from the Bicycle Basin, which is also the highest production capacity basin. However, the rate of groundwater withdrawal exceeds the recharge rate and it is expected that Bicycle Lake water quality will deteriorate with time. Table 2 Typical Source Quality Constituent Units Typical Source Range Min Max Average ph 7.2 8.9 8.1 Conductivity µs/cm 859 937 890 Fluoride mg/l 2.9 8.4 5.22 Arsenic µg/l 9.5 32 23 Reactive Silica mg/l 24 88 73 Total Silica mg/l 76 87 81 TDS mg/l 540 670 592 Total Iron µg/l <8.3 a 36 20 Dissolved Iron µg/l <8.3 a 10.5 8.7 Total Manganese µg/l <0.06 a 0.68 0.35 Dissolved µg/l <0.06 a 0.53 0.29 Manganese Nitrate mg/l as N 1.5 5.9 4.04 Sulfate mg/l 125 155 138 Total Alkalinity mg/l as CaCO3 136 174 145 Barium mg/l 31 37 33 Sodium mg/l 142 181 154 Chloride mg/l 80.9 133 91.3 Chromium (VI) µg/l 5.6 15.0 11.0 a Non-detect results shown as less than detection limit Ft Irwin established up to 14 groundwater well blend scenarios and provided the projected blended source water quality based on historical data. These were provided to represent average as well as boundary source water quality conditions that should be anticipated at the new IWW. GE used their proprietary EDR performance projection software and developed corresponding EDR waste stream water qualities for all 14 scenarios. To facilitate subsequent design considerations and evaluations, the 14 scenarios were narrowed down into 3 summary EDR waste stream water quality scenarios. These address the overall average water quality (Ambient water quality) as well as two additional scenarios that bound each critical water quality parameter on the high end value side (Moderately High TDS and High TDS water qualities). In addition, the Moderately High TDS water quality represents a situation where the total alkalinity is less than the total hardness on an equivalents basis, thus representing a situation where the removal of non-carbonate hardness is required. The Ambient water quality condition establishes typical or average operating conditions and is also most likely representative of the highest flow water quality conditions. The Moderately High TDS and High TDS water quality conditions help set the most difficult treatment conditions relative to chemical dosing and process operations. Table 3 summarizes the design feed water quality scenarios for the IWW. 13
Table 3 Design Feed Quality Scenarios Units Ambient Quality Moderately High TDS a High TDS Quality Calcium mg/l 24.75 63 68 31.6 Magnesium mg/l 4.2 10 5.4 Sodium mg/l 167.8 168.9 171.2 213.4 Potassium mg/l 8.9 9-9.4 10.3 Strontium mg/l 0.4 0.64-600 0.4 Barium mg/l 0.02 0.04-19.7 0.02 Arsenic µg/l 25 4.4-40 30 Ammonium mg/l ND c ND c - 0.06 ND c Bicarbonate mg/l 178.6 139.9-140 227.9 Sulfate Chloride mg/l mg/l 123.9 135.3 158.7 158.7 133.4 231.3 133.4 104.6 Fluoride mg/l 5.1 1.3-5.5 8.75 Nitrate mg/l 20.3 19.8-20.8 32.4 Silica (as SiO2) b mg/l 52.3 20.3-47.5 66.7 Total Dissolved Solids mg/l 690 199-790 890 ph SU 7.79 7.9-8.1 7.79 a Range based on multiple blends b SiO2 = silicon dioxide c Non-Detect The new IWW Process Flow Diagram is presented in Figure 12. The overall plant consists of two process flow streams, the Main Treatment Train where EDR is used to achieve 92 percent recovery, and the Secondary Waste Recovery Train where both reverse osmosis (RO) and mechanical evaporation (ME) are used to raise overall plant recovery to greater than 99 percent. The remaining process flow stream relates to non-recoverable residuals management and includes sludge holding and thickening basins as well as solar evaporation ponds. 14
Figure 12 IWW Process Flow Diagram The new IWW is designed to produce 6 mgd of treated water. EDR feedwater flows are approximately 6.52 mgd to achieve 6 mgd of treated water. This results in an approximate 0.52 mgd (362 gpm) of EDR waste flow that must be treated in the Secondary Waste Recovery Train. The waste stream recovery must reach a minimum of 88 percent recovery (0.46 mgd or 320 gpm) to achieve an overall plant recovery of 99 percent. Main Treatment Train The main treatment train at the IWW consists of untreated water storage, feedwater pumping, cartridge filters, the EDR membrane system, product water disinfection and stabilization, and treated water storage and distribution (see Figure 13). 15
Figure 13 Main Treatment Train Flow Diagram Ft Irwin determines which wells (and groundwater basins) are to be used and the blended source water is stored in a 1 million gallon (MG) Untreated Storage Tank (UWST). Untreated water pumps boost the untreated water through cartridge filters ahead of the EDR membranes. Ft Irwin chlorinates the untreated groundwater to reduce the potential for any bacterial growth in the conveyance system upstream of IWW, while also oxidizing any dissolved iron and manganese that may be present. A residual of approximately 0.5 mg/l is targeted for the untreated water feed at the IWW facility. The EDR membrane system includes five identical EDR units as manufactured by GE (GE- Ionics EDR 2020 units). The units are rated at 1.5 mgd of product water, resulting in a firm production capacity of 6.0 mgd with one standby unit. Each unit includes the membrane stacks, reversal and outlet modules, concentrate recycle/waste system, and electrical control modules. Associated systems include the CIP and ECIP systems. Product water from each EDR unit is routed to the Treated Storage Tank. Sodium hypochlorite is applied to provide a chlorine residual in the distribution system. Product water is stabilized by adding carbon dioxide to suppress ph and lime slurry to add alkalinity and hardness. Off-spec product and EDR concentrate are discharged to a waste equalization tank for subsequent treatment through the Secondary Treatment Train. EDR systems using the previous generation of platinum electrodes generated a continuous waste stream from the electrode compartments due to the formation of oxygen and chlorine gas and hydrogen ions at the anode, and the formation of hydrogen gas and hydroxyl ions at the cathode. The electrode waste would be blended to neutralize the hydrogen and hydroxyl ions, sent through a degasifier to strip the gasses, and then discharged to waste or recycled back to the feed side. 16
The latest generation of carbon electrodes do not generate a continuous waste stream, which eliminates the need an electrode waste degasifier. With the newer electrodes, feed water flowing through the electrode compartments becomes either product or concentrate, depending on the polarity of the stack. EDR product water is continuously monitored for conductivity. If the conductivity exceeds the set point, the product is automatically diverted to waste through the off-spec product valve. Hydrochloric acid and scale inhibitor are continuously added to the recirculating concentrate loop to aid in scale prevention. Projected EDR product and waste stream water qualities for the three source water quality scenarios discussed previously are included in Table 4 and Table 5, respectively. The waste stream quality is based on a blend of the two EDR waste streams. Table 4 Summary EDR Product Quality Scenarios Units Ambient Quality Moderately High TDS Quality a High TDS Quality CATIONS Calcium mg/l 1.8 4.5-6.2 2.0 Magnesium mg/l 0.4 0.8-1.2 0.4 Sodium mg/l 21.9 21.4-31.7 23.3 Potassium mg/l 0.9 0.9-1.3 0.8 Strontium mg/l 0.02 ND d - 0.03 0.02 Barium mg/l ND d ND d ND d Arsenic µg/l 2.7 2.1-4.1 2.6 Ammonium mg/l 0.02 ND d - 0.03 0.02 ANIONS Bicarbonate mg/l 30.3 22.3-31.3 31.5 Sulfate mg/l 9.5 9.2-13.9 9.9 Chloride mg/l 11.4 21.6-33.9 11.7 Fluoride mg/l 0.9 0.30-0.92 1.3 Nitrate mg/l 2.4 2.2 3.1 3.1 Total Orthophosphate mg/l ND d ND d ND d OTHER Silica (as SiO2) b mg/l 52.3 20.3 47.5 66.7 Total Dissolved Solids mg/l 132 104 171 151 Total Hardness (as mg/l 6.0 14.6 20.4 6.5 CaCO3) c Conductivity µs/cm 134 151 217 142 ph SU 7.02 7.2-7.3 6.93 a Range based on multiple blends 17
CATIONS b SiO2 = silicon dioxide Units Ambient Quality Moderately High TDS Quality a High TDS Quality c CaCO3 = calcium carbonate d Non-Detect e Calculated from calcium and magnesium values Table 5 Summary EDR Waste Stream Quality Scenarios Units Ambient Quality Moderately High TDS Quality a High TDS Quality CATIONS Calcium mg/l 289 716-798 373 Magnesium mg/l 48.4 112-116 63 Sodium mg/l 1,845 1,775-1,865 2,400 Potassium mg/l 101 98 107 119 Strontium mg/l 4.78 0.23-7.1 4.8 Barium mg/l 0.23 0.23-0.47 0.24 Arsenic µg/l 281 155-453 345 Ammonium mg/l 0.42 0.38 0.44 0.43 ANIONS Bicarbonate mg/l 1,849 1,341-1,418 2,395 Sulfate mg/l 1,440 1,519 1,532 1,870 Chloride mg/l 1,182 2,402 2,510 1,548 Fluoride mg/l 53.5 13 58 94.9 Nitrate mg/l 226 212-228 370 Total Orthophosphate mg/l ND d 0.0 0.33 ND OTHER Silica (as SiO2) b mg/l 52.3 20.3 47.5 66.7 Total Dissolved Solids mg/l 7,099 8,367-8,535 9,309 Total Hardness (as CaCO3) c mg/l 921 e 2,251 2,473 e 1,191 e Conductivity µs/cm 9,089 10,873-11,116 11,539 ph SU 7.85 7.55 7.7 7.64 a Range based on multiple blends b SiO2 = silicon dioxide c CaCO3 = calcium carbonate d Non-Detect e Calculated from calcium and magnesium values 18
STARTUP Startup of the EDR system involves several stages of checking and testing including initial checkout and functional testing, disinfection of the system, and performance testing. Test water for startup was supplied from the existing DO system. The functional testing phase begins with initial checkout of the EDR system. Initial checkout requires that the EDR system manufacturer (GE) confirm that all installation work was complete, that all safety devices were installed, and that all equipment was ready for operation. Functional testing requires calibration of testing equipment, hand turning of motors to check for binding, checking power to electrical equipment, adjusting clearances, rotation checks for motors, checking component lubrication, and checking all control loops. Performance testing of the EDR system requires a number of other major sub-systems to be complete, disinfected (if required), and ready for operation including the following: Untreated water storage tank (UTWST) Untreated water pumps Cartridge filters Air stripper Process drain pump station (PDPS) Waste equalization storage tank (WET) Lime sludge lagoons Lime sludge lagoon pump station (LSLPS) Evaporation ponds Treated water storage tank (TWST) Treated water pump station (TWPS) During initial performance testing, the EDR membrane stacks are not energized and no chemicals are added to the process streams. Initial testing of the EDR main process flow stream requires pumping untreated water through the EDR trains and on to the TWST. The test water is then be returned to the existing DO system via the treated water pump station. Initial testing of the EDR waste flow streams requires pumping water through the EDR trains and through the OSP valve to the WET or through the concentrate blowdown valve to the air stripper. From the air stripper, the test water flows into the PDPS for subsequent pumping to the WET. Any excess test water in the WET was can be discharged to the LSLPS for subsequent pumping to the evaporation ponds. Prior to performance testing, the EDR system and associated systems were disinfected to allow any test water sent to the TWST to be discharged to the existing DO system. The UTWST and TWST were disinfected in accordance with AWWA Standard C652, Disinfection of Storage Facilities. Yard piping designed to convey untreated water, treated water, and recoverable waste water were disinfected in accordance with AWWA Standard C651, Disinfecting Mains. The EDR system was disinfected in accordance with AWWA Standard C653, Disinfection of Treatment Plants. 19
Performance testing of the EDR system first requires pumping test water through the EDR stacks without operating the concentrate pumps. This is to confirm there are no problems such as leaks, or hydraulic limitations within the EDR train or in the process piping. Test water is discharged through the OSP valve to check the off-spec water piping, then through the product water valve to check the product water piping. To simulate normal operation, the test water is pumped through the EDR stacks and the concentrate pump is started to check the concentrate recycle and blow down systems. As of November 24, 2015, functional testing was complete and performance testing had begun. Because performance testing is not yet complete, information and data from this phase of testing is not available yet. Results from performance testing and actual operation of the system will likely be published at a later date. SUMMARY EDR is a membrane process that can effectively reduce arsenic, fluoride, as well as nitrates and TDS in high fouling waters with minimal pretreatment and a high recovery. The EDR system at the IWW will produce 6 mgd of product water at a recovery of 92 percent. The waste from the EDR system will be further treated to increase the overall plant recovery to greater than 99 percent, while discharging no liquid waste. Functional testing is complete and performance testing is underway. Information and data from performance testing is not available yet. Results from this phase and data from actual operation will likely be published at a later date. The Ft Irwin facility provides a critical function in the preparedness of United States defense capabilities. A critical factor in sustaining the Ft Irwin facility is a safe and reliable potable water supply to serve the military personnel, their families, government civilian staff and contractors, as well as visitors. Utilizing EDR at the IWW will allow Ft Irwin to meet its goals of producing high quality drinking water while conserving their limited resources to provide a reliable water source for the base and its personnel for many years to come. REFERENCES 1. O Neil, W.K., Thompson, D., Cutler, D., Kimball, R., Yoshimura, J. New High Recovery Fort Irwin Works Supports Critical Army Training Mission. Paper presented at the American Membrane Technology Conference, Las Vegas, NV, March 10 13, 2014. 2. California Department of Health Services (CDPH). Domestic Supply Permit and Engineering Report for Consideration of the Permit Application from United States Department of the Army, Fort Irwin System. February 2004. 3. Code of Federal Regulations, Title 40, Chapter I, Section 141.62 4. U.S. Department of Health and Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry. Toxicological Profile for Arsenic. August 2007. 20
5. National Research Council. Fluoride in Drinking : A Scientific Review of EPA's Standards. Washington, DC: The National Academies Press, 2006. 6. California Code of Regulations, Title 22, Division 4, Chapter 15, Article 4, Section 64431 7. CH2MHILL. Fort Irwin Treatment Process Selection Based on Pilot Testing Results. February 2007. 8. Alborzfar, M., Cox, E. Providing Quality to Our Customers: Pilot Testing of EDR for Fluoride, Arsenic, and TDS Removal at Fort Irwin, California. AWWA Membrane Technology Conference, 2007. 9. American Works Association. Manual of Supply Practices M38 Electrodialysis and Electrodialysis Reversal. 1999. 21