WaterRF Perchlorate ResearchWaterRF Perchlorate Research
In 1997, elevated levels of perchlorate In 1997, elevated levels of perchlorate were discovered in California drinking were discovered in California drinking ggwater supplieswater supplies
In 1998, entered into a partnership In 1998, entered into a partnership agreement with East Valley Water agreement with East Valley Water District (two years before release of District (two years before release of movie “Erin Brokovich”)movie “Erin Brokovich”)
Since 1998, WaterRF funded 18 Since 1998, WaterRF funded 18 projects with total research value over projects with total research value over $7 Million$7 Million
WaterRF Perchlorate ProjectsWaterRF Perchlorate Projects National Assessment of Perchlorate Contamination National Assessment of Perchlorate Contamination
Occurrence (Order 90902, 2002)Occurrence (Order 90902, 2002) Biological Destruction of Perchlorate and Nitrate in Ion Biological Destruction of Perchlorate and Nitrate in Ion
Exchange Concentrate (Order 3137, 2010)Exchange Concentrate (Order 3137, 2010) Treatability of Perchlorate in Groundwater Using IonTreatability of Perchlorate in Groundwater Using Ion Treatability of Perchlorate in Groundwater Using Ion Treatability of Perchlorate in Groundwater Using Ion
Exchange Technology, Phase I and II (Order 91038F and Exchange Technology, Phase I and II (Order 91038F and 91016F, 2004)91016F, 2004)
Membrane Biofilm Reactor Process for Nitrate and Membrane Biofilm Reactor Process for Nitrate and Perchlorate Removal (Order 91004F, 2004)Perchlorate Removal (Order 91004F, 2004)
Application of Bioreactor Systems to LowApplication of Bioreactor Systems to Low--Concentration Concentration Perchlorate Contaminated Water (Order 91017F and Perchlorate Contaminated Water (Order 91017F and 90982F, 2004)90982F, 2004)
GAC Use, Tailoring and Regeneration for Perchlorate GAC Use, Tailoring and Regeneration for Perchlorate Remo al from Gro nd ater (Order 91035F 2004)Remo al from Gro nd ater (Order 91035F 2004)Removal from Groundwater (Order 91035F, 2004)Removal from Groundwater (Order 91035F, 2004)
Treatability of Perchlorate Containing Water by RO, NF and Treatability of Perchlorate Containing Water by RO, NF and UF Membranes (Order 90932F, 2002)UF Membranes (Order 90932F, 2002)
www.waterrf.orgwww.waterrf.org “search” by project number“search” by project number
UCMR1: Unregulated Contaminant Monitoring Rule 1Source: Brandhuber et al., 2009
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P l ti ti t f P bli W t S t (PWS) th t d t t d
Threshold Range of Population Served by PWSs with at Least 1 Detection > threshold (Million)
4 g/L 5.1 – 16.6
6 g/L 3 0 – 11 8
Population estimates for Public Water Systems (PWS) that detected perchlorate above various thresholds (GAO, 2010).
6 g/L 3.0 – 11.8
9 g/L 1.6 – 5.2
14 g/L 0.9 – 2.1
19 g/L 0.7 – 1.6
23 g/L 0.4 – 1.0
Note: All occurrence measures were conducted on a basis reflecting values greater than the listed thresholds.All population estimates are rounded.
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• Key factors for selection of method include
– Policy issues and acceptance of method by regulatory agencies
– Laboratory certification • State or Federal
– Sensitivity• Capability of a method or instrument
to differentiate betweento differentiate between measurement responses representing different levels
– Selectivity• Capability of a method or instrument
to respond to a target substance or constituent in the presence of non-target substance
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Method Description MDL (ppb)
MRL (ppb)
Date
EPA 314.0 IC 0.5 2.0 Nov 1999
EPA 331.0-1 IC/MS 0.02 0.05 Jan 2005
EPA 332.0 IC/MS 0.04 0.10 March 2005
EPA 314.1-1 IC w/ inline concentration
0.03 0.10 May 2005
• EPA 314.0 is the most commonly used method
• EPA 331.0-1 is widely available and often used if higher sensitivity is required.
EPA 314.2 2-D IC 0.012 0.14 May 2008
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• Perchlorate is an endocrine disrupterPerchlorate is an endocrine disrupter– High perchlorate levels interfere with iodide
uptake and inhibit thyroid function and production of triiodothyronine (T3) and thyroxine (T4) hormones (Siddiqui et al., 1998; Buffleret al., 2006; Kucharzyk et al., 2009).
• Major health concernPlays a major role in proper development
Cells in the body require thyroid hormones for
maintaining metabolism
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– Plays a major role in proper development and metabolism of children
– more susceptible group: infants, unborn fetuses, and pregnant mothers (EPA, 2005).
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1992/1995 •Provisional Rfd issued by EPA of 0.0001 mg/kg/dayy g g y•Revised provisional RfD issued by EPA of 0.0005 mg/kg/day
1997•Discovered in groundwater in CA•CDPH establishes Notification Level of 18 ppb
In cooperation with the Office of Environmental Health Hazard Assessment (OEHHA) Based on EPA reference dose (RfD) range of 4-18 ppb from the 1992/1995 studies
1998/1999 EPA dd d hl t t th d i ki t t i t li t (CCL)
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1998/1999 •EPA added perchlorate to the drinking water contaminants list (CCL)•Monitoring mandated by the Unregulated Contaminants Monitoring Rule (UCMR)
2002
•EPA released a revised draft toxicity assessment •CDPH lowered Notification Level to 4 ppb
2004 OEHHA t bli h d PHG f 6 b2004 •OEHHA established PHG of 6 ppb•CDPH adjusts Notification Level to 6 ppb
2006 •CA MCL proposed at 6 ppb
2008/2009 •EPA releases preliminary determination that perchlorate does not present a meaningful health risk•EPA sets interim health advisory value of 15 ppb
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•EPA sets interim health advisory value of 15 ppb
2011 •EPA determines that perchlorate meets SDWA criteria (February 11th)
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Regulatory Level States
1 ppb CaliforniaMaryland
MassachusettsNew Mexico
2011 – Public Health Goal2006 – Advisory Level2006 – Minimum Reportable Limit
2009 – Proposed Maximum Contaminant LevelAdvisory Level
6 ppb California 2007 – Maximum Contaminant Level
14 ppb Arizona 2003 – Health Based Guidance Level
18 ppb Nevada 1997 – Advisory Level
DEVELOP proposed National Primary Drinking Water p p y gRegulation (NPDWR)
PUBLISH a proposed NPDWR for public review and comment within 24 months starting February, 2011.
EVALUATE the science as the NPDWR is developed.
PRESENT a health risk reduction and cost analyses PRESENT a health risk reduction and cost analyses, an analysis of feasible treatment methods, and an analysis of small system compliance technologies.
CONSULT with the National Drinking Water Advisory Council, the Science Advisory Board, and the Secretary of Health and Human Services, as required under SDWA.
Other Specific Considerations– Biological: presence of indigenous microbes
– In Situ: site hydrogeological variables
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• Ion Exchange (IX)
• Activated Carbon
• Nanofiltration (NF) and Reverse Osmosis (RO)
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• Electrodialysis (ED) and Electrodialysis
Reversal (EDR)
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• Polymer-based resin with charged functional groups is utilized to remove specific ions from solution, replacing them with ions already on the resin
CHCH2 CH2 CH CH2
DivinylbenzeneStyrene
ION1 ION2
• Anion exchange:Positively charged quaternary amine functional groups in the chloride form (counter ion) exchange the negatively charged anions (perchlorate ion) in the feed solution
• Typical bed volume treatment rates– 500 to 5000 BV for regenerable IX
– 100,000 – 200,000 BV for single use IX 28
Polystyrene divinylbenzene weak-
base anion resin. 6 ppb < 0.19 ppb
Fontana Water Company, Fontana, California (ITRC,
2008).
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• GAC media is manufactured from high• GAC media is manufactured from high carbon content materials such as coal, wood, or coconut shells. Positively charged sites on the GAC media are used to adsorb negatively charged perchlorate ions.
• To increase positively charged surface functionalities GAC is tailored to
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functionalities, GAC is tailored to increase adsorption capacity
• Tailoring agents include monomers, polymer, organic iron complexes or quarternary amines (Parette and Cannon, 2006)
Mechanism • Negatively charged perchlorate adsorbed onto positively charger surface active material
OperationalConsiderations
• Service load• Product water quality• Change-out frequency
Regeneration • Thermal regeneration
Configuration • Columns arranged in series or parallel 30
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Application Influent
Concentration Effluent
Concentration Reference
T-GAC with cetyltrimethyl
ammonium chloride.75 ppb < 6 ppb Graham et al., 2004.
T-GAC with cationic surfactants.
75 ppb < 1 ppbParette and Cannon,
2005.
• Based of laboratory and field-scale studies
• Adsorption capacity increased by 30-40% with tailored GAC
• Typical bed volumes of 10,000 – 30,000 BV 31
T-GAC with iron-oxalic acid.
60 – 80 ppb < 7 ppb Na et al., 2002.
Wh i li d t• When pressure is applied to membranes, water flows in the reverse direction to natural osmotic flow resulting in rejection of dissolved salts by the membrane.
• Some of the dissolved salts may pass through the membrane.
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pass through the membrane. – NF is typically used for softening
(calcium and magnesium removal).
– RO is used for removing monovalent ions (sodium, chloride, etc.).
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Target• Total Dissolved Solids (TDS)• MetalsTarget
contaminant• Metals• Organics • Trace elements
Types of Membranes
• NF: Primarily for hardness and TOC removal, Typical MWCO ~ 300 Da• RO: TDS removal, Typical MWCO ~ 100 Da• Material: Cellulose acetate, Thin film composite poly amide
Mechanism • Solution diffusion as transport mechanism. Rejection based on si e and charge e cl sionMechanism based on size and charge exclusion.
Operatingparameters
• Flux: 12 – 16 gfd for brackish groundwater treatment• Recovery: 80 – 85% for brackish groundwater treatment
Cleaning • Membranes need to be cleaned when fouling/scaling occurs
Configuration • Typically 8-inch diameter spiral wound elements arranged as an array
• Removal of dissolved salts by application of electrical potential difference and ion selective membranes.
• Recovery of ED/EDR process is typically higher than RO process.
35
typically higher than RO process. Energy requirement is proportional to salinity of feed water.
Target • Total Dissolved Solids (TDS)Target contaminant
( )• Metals• Trace elements
Types of Systems
• ED: Electrodialysis using cation and anion exchange membranes with electric field • EDR: Similar to ED with polarity reversal for operation with more turbid groundwater
Mechanism• Desalination of water due to anions and cations electro-migration through ion selective membranes when electric field (DC) is applied between electrodesfield (DC) is applied between electrodes
Operating parameters
• Recovery: > 85% for brackish groundwater treatment
+ Proven technology+ Most effective & commonly used+ Highly regenerable- Generates concentrated brine stream- Impacted by competing anions
$100 – 450/AF
Carbon Adsorption 60 – 80 ppb + Existing facilities can be used+ No waste brine is created- GAC tailoring needed for high efficiency- Regeneration efficiency limited
$60 – 120/AF
High Pressure 100 800 ppb + Multicontaminant removal $450+/AF
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High-Pressuremembranes
100 – 800 ppb + Multicontaminant removal- High capital and O&M- Generates large quantity of brine- High energy
$450+/AF
ElectrodialysisReversal
10 – 130 ppb + Multicontaminant removal- High capital and O&M- Generates large quantity of brine
$350+/AF
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39
• Fluidized Bed Reactor (FBR)
• Packed Bed Reactor (PBR)
• Membrane Biofilm Reactor (MBfR)
I Sit Bi di ti (ISB)
e-
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• In Situ Bioremediation (ISB)
• Permeable Reactive Barrier (PRB)
ClO4- Cl-
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• Microorganisms grown on media (substrate) reduce g g ( )perchlorate
• In PBR systems, the media is stationary. In FBR systems, the media is fluidized
• Systems can be controlled to be operated in aerobic, bi i diti d di t t t
41
anaerobic, or anoxic conditions depending on treatment requirement.
• Multi-contaminant remove is often possible
Target • PerchlorateTarget contaminant
• Perchlorate• Nitrate
Types of Media• Sand• Activated carbon• Plastic (PBR)
Mechanism• Media provides large surface area for growth of microorganisms. Microorganisms completely reduce perchlorateperchlorate.
OperationalConsiderations
• Addition of nutrients• Addition of electron donor
Configuration
• Cylindrical tanks used as reactor for media and biomass. • Feed flow at bottom and effluent from top of tank (FBR). Upflow (or) downflow (PBR).
and a buffer. 430,000 ppb <4 ppb after 105 days Hatzinger, et al., 2003.
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• Reactive barrier consists of reactive material that reduce perchlorate
• Reactive material provide electron donors and
t i t f i bi l th PRB
Contaminated Groundwater
TreatedGroundwater
51
nutrients for microbial growth– Woodchips
– Edible oil
– Compost material
– etc,.
PRB
Target contaminant
• Perchlorate• Nitrate
Mechanism • Controlled biological process• Reactive material degrades perchlorate completely
Operating Additi f t i tOperating requirements
• Addition of nutrients• Survival of electron donor
Configuration • Reactive material filled in barrier wall build to cut-off contaminated groundwater plume
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TechnologyInitial
Concentration Final
ConcentrationReference
Gravel-size scoria, apatite, pecan shells and cotton seed
with mixture of gravel and limestone.
120 ppb 20 ppb EPA, 2005.
Mixture of gravel (70%), mushroom compost (20%),
and soybean oil soaked13,000 ppb < 0.45 ppb Beisel et al., 2004.
53
and soybean oil-soaked woodchips (10%).
Emulsified edible oil substrate (EOS).
10,000 ppb < 4 ppb Lieberman et al.,
2004.
Technology TypicalInfluent Perchlorate
Advantages &Limitations
Water Production Costs
Fluidized Bed Reactor/Packed Bed Reactor
8 – 10,000+ ppb + Proven technology+ Cost effective compared to IX- Acclimation of microorganisms- Public Acceptance
$90 - $360/AF
MembraneBiofilm Reactor
50 – 1,000 ppb + No brine- Reactor efficiency- Still under development
$300-$1,000/AF
In situ 500 000+ ppb + Treats high levels of perchlorate $2 500+/AF
54
In situBioremediation
500,000+ ppb + Treats high levels of perchlorate-Time-consuming- Efficiency depends on nutrient availability
$2,500+/AF
Permeable Reactive Barrier
10,000 + ppb + Treats high levels of perchlorate- Time consuming process- Efficiency depends on nutrient availability
$130 - 210/AF
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• GAC with biological growth• GAC with biological growth (biological activated carbon) (Choi et al., 2008).
• Biological treatment of ion exchange brine (Lehman et al., 2008; Patel et al., 2008; Xiao et al., 2010). Biological
Brine
Removal Technology
55
• EDR brine treated with PBR (Brown et al., 2010).
• Primary drawback: acclimating salt-tolerant bacteria in the reactor (Alridgeet al., 2004).
Treatment
56
• Biological brine treatment allows for reuse of brine
• Salt consumption can be significantly reduced
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• Enhanced Ultrafiltration: Polyelectrolyte colloid micelle chitosanPolyelectrolyte, colloid, micelle, chitosanenhanced UF (Yoon et al., 2003; Huq et al., 2007;
Xie et al., 2011).
• Chemical and electrochemical reduction: Utilization of catalysts to exceed the activation energy of perchlorate to enhance reduction (Hurley et al 2007; Wangenhance reduction (Hurley et al., 2007; Wang et al., 2008).
• Ultraviolet laser reduction: UV light in the presence of metallic iron powder has to provide the activation energy for reduction of perchlorate to chloride (ITRC, 2008). 57
• Zero valent iron (ZVI): ( )ZVI in combination with microorganisms has been shown to reduce more than 99% of perchlorate (Yu et al., 2006; Yu et al.,2007).
• Catalytic hydrogen gas membrane: More than 90% perchlorate reduction has been reported using non-precious metal catalysts. (Huang, 2005; ITRC, 2008).
• Phytotechnology: Utilization of plants (willow, hybrid poplar, cottonwood, water lily) for perchlorate reduction. (FRTR, 2005). 58
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• Perchlorate contamination is more predominant in Western U it d St t b t b l t if l tiUnited States, but may be more prevalent if regulations are revised to lower levels.
• Contamination concern is primarily related to thyroid function impairment although toxicity at very low levels is unknown.
• A wide variety of current and emerging technologies exist to
59
A wide variety of current and emerging technologies exist to treat perchlorate.
• Choice of which technology to use is very dependent on the concentration of perchlorate in the water and any matrix effects.
• Removal Technologies: Ion exchange shows the most i l t h l i it i tpromise among removal technologies, as it is most
commonly used and effective. Concentrate brine is generated with removal technologies.
• Reduction technologies: Typically biological in natgure, completely reduce perchlorate into chloride and oxygen. Require electron donor and nutrient addition for maintaining efficiency
60
efficiency.
• Emerging technologies under development show promise at improving and enhancing perchlorate removal, but are restricted to laboratory applications.
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• United States Government Accountability Office (GAO), 2010. Occurrence is widespread but at varying levels: Federal agencies have taken some actions to respond to and lessen releases. http://www.gao.gov/new.items/d10769.pdf
• Brandhuber, P., Clark, S., Morley, K., 2009. A review of perchlorate occurrence in public drinking water systems, Journal AWWA, 101, 63 – 73.
• Siddiqui, M., LeChevallier, M.W., Ban, J., Phillips, T., Pivinski, J., 1998. Occurrence of perchlorate and methyl tertiary butyl ether (MTBE) in groundwater of the American Water System. American Water Works Service Company, Inc., Vorhees, New Jersey, September 30.
• Buffler, P.A., Kelsh, M.A., Lau, E.C., Edinboro, C.H., Barnard, J.C., Rutherford, G.W., Daaboul, J.J., Palmer, L., Lorey, F.W., 2006. Thyroid function and perchlorate in drinking water: An evaluation among California newborns 1998 Environmental Health Perspective 114 798 –
61
evaluation among California newborns, 1998. Environmental Health Perspective, 114, 798 –804.
• Kucharzyk, K.H., Crawford, R.L., Cosens, B., Hess, T.F., 2009. Development of drinking water standards for perchlorate in the United States. Journal of Environmental Management, 91, 303 – 310.
• The Interstate Technology and Regulatory Council (ITRC), 2008. Remediation technologies for perchlorate contamination in water and soil. Washington D.C.
• Parette, R., Cannon, F.S., 2006. Perchlorate removal by modified activated carbon, in Perchlorate Environmental Occurrence, Chemistry, Toxicology, and Remediation Technologies, Springer, New York.
• Graham, J.R., Cannon, F.S., Parette, R., Headrick, D., Yamamato, G., 2004. Commercial demonstration of the use of tailored carbon for the removal of perchlorate ions from potable water. Presented at National Groundwater Association Conference on MTBE and Perchlorate, Costa Mesa, California, June 3 – 4.
• Parette, R., Cannon, F.S., 2005. The removal of perchlorate from groundwater by activated carbon tailored with cationic surfactants. Water Research 39, 4020 – 4028.
• Yoon, Y., Amy, G., Cho, J., Her, N., Pellegrino, J., 2002. Transport of perchlorate (ClO4-)
through NF and UF membranes. Desalination 147, 11 – 17.
• Yoon, J., Amy, G., Chung, J., Sohn, J., Yoon, Y., 2009. Removal of toxic ions (chromate, arsenate, and perchlorate) using reverse osmosis, nanofiltration, and ultrafiltration membranes. Chemosphere 77, 228 – 235.
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• Wang D M Huang C P 2008 Electrodualytically-assisted catalytic reduction (EDACR) ofWang, D.M., Huang, C.P., 2008. Electrodualytically assisted catalytic reduction (EDACR) of perchlorate in dilute aqueous solutions. Separation and Purification Technology, 59, 333 – 341.
• Roquebert, V., Booth, S., Cushing, R.S., Crozes, G., Hansen, E., 2000. Electrodialysis reversal (EDR) and ion exchange as polishing treatment for perchlorate treatment. Desalination, 131, 285 – 291.
• Webster, T.S., Guarini, W.J., Wong, H.A., 2009. Fluidized bed bioreactor treatment of perchlorate-laden groundwater to potable standards. Journal AWWA, 101, 137 – 151.
• Sartain, H.S., Mark, C., 2003. Ex situ treatment of perchlorate-contaminated groundwater. Presented at In Situ and On-site bioremediation – The Seventh International Symposium. June
63
2 – 5.
• Beisel. T.H., Mark, C., Perlmutter, M., 2004. Ex situ treatment of perchlorate contaminated groundwater. Presented at National Ground Water Association (NGWA) Conference on MTBE and Perchlorate. June 3 – 4.
• Rittmann, B.E., Nerenberg, R., Lee, K.C., Najm, I., Gillogly, T.E., Lehman, G.E., Adham, S.S., 2004. The hydrogen-based hollow-fiber membrane biofilm reactor (HFMBfR) for removing oxidized contaminants. Water Science and Technology: Water Supply, 4, 127 – 133.
• APTwater, 2009. Membrane Biofilm Reactors. Presentation by Aptwater Inc., February 10.
• Owsianiak, L.M., Lenzo, F., Molnaa, B., 2003. In site removal of perchlorate from perched groundwater by inducing enhanced anaerobic conditions. Presented at the Seventh International In Situ and On-site Bioremediation Symposium, June 2 – 5.
64
• Rosen, J., 2003. Successful in site bioremediation of perchlorate in groundwater. Poster presented at the SERDP Technical Symposium and Workshop, Washington D.C., November 30 – December 2.
• Cox, E., Evan, E., Neville, S., 2003. In site bioremediation of perchlorate: Comparison of results from multiple field demonstrations. Presented at In Site and On-Site Bioremediation –The Seventh International Symposium, June 2 – 5.
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• The Interstate Technology and Regulatory Council (ITRC), 2008. Remediation technologies for perchlorate contamination in water and soil. Washington D.C.
• Hatzinger, P.B., Engbring, D.E., Giovanelli, M.R., Diebold, J.B., Yates, C.A., Cramer, R.J., 2003. Field evaluation of in situ perchlorate bioremediation at the Indian Head Division, Naval Surface Warfare Center. Presented at In Situ and On-Site Bioremediation – The Seventh International Symposium, June 2 – 5.
• Beisel. T.H., Mark, C., Perlmutter, M., 2004. Ex situ treatment of perchlorate contaminated groundwater. Presented at National Ground Water Association (NGWA) Conference on MTBE and Perchlorate. June 3 – 4.
• Lieberman, M.T., Zawtocki, C., Borden, R.C., Birk, G.M., 2004. Treatment of perchlorate and trichloroethane in groundwater using edible oil substrate (EOS) Proceedings of the National
65
trichloroethane in groundwater using edible oil substrate (EOS). Proceedings of the National Ground Water Association Conference on MTBE and Perchlorate: Assessment, Remediation and Public Policy, Costa Mesa, California, June 3 – 4.
• Choi, Y.C., Li, X., Raskin, L., Morgenroth, E., 2008. Chemisorption of oxygen onto activated carbon can enhance the stability of biological perchlorate reduction in fixed bed biofilm reactors. Water Research, 42, 3425 – 3434.
• Lehman, S.G., Badruzzaman, M., Adham, S., Roberts, D.J., Clifford, D.A., 2008. Perchlorate and nitrate treatment by ion exchange integrated with biological brine treatment. Water Research, 42, 969 – 976.
• Patel, A., Zuo, G., Lehman, S.G., Badruzzaman, M., Clifford, D.A., Roberts, D.J., 2008. Fluidized bed reactor for the biological treatment of ion-exchange brine containing perchlorate and nitrate. Water Research, 42, 4291 – 4298.
• Xiao, Y., Roberts, D.J., Zuo, G., Badruzzaman, M., Lehman, S.G., 2010. Characterization of micronial populations in pilot-scale fluidized-bed reactors treating perchlorate- and nitrate-laden brine. Water Research, 44, 4029 – 4036.
• Brown, J.C., Wheadon, R., Hansen, E., 2010. Biodestruction of blended residual oxidants. Journal AWWA, 102, 71.
• Aldridge, L., Gillogly, T., Lehman, G., Clifford, D.A., Roberts, D., Lin, X., 2004. Treatability of perchlorate in groundwater using ion exchange technology – Phase II. AwwaRF, Denver, Colorado
66
Colorado.
• Lehman, S.G., Adham, S., Burbano, Suvendran, S., 2008. Evaluation of biological treatment for perchlorate-impaired water supplies. U.S. Bureau of Reclamation Final Report # 116.
• Yoon, J., Yoon, Y., Amy, G., Cho, J., Foss, D., Kim, T.H., 2003. Use of surfactant modified ultrafiltration for perchlorate (ClO4
-) removal. Chemosphere 37, 2001 – 2012.
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• Huq, H.P., Yang, Y.S., Yang, J.W., 2007. Removal of perchlorate from groundwater by the polyelectrolyte – enhanced ultrafiltration process. Desalination 204, 335 – 343.
• Xie, Y., Li, S., Wu, K., Wang, J., Liu, G., 2011. A hybrid adsorption/ultrafiltration process for perchlorate removal. Journal of Membrane Science 366, 237 – 244.
• Huq, H.P., Yang, Y.S., Yang, J.W., 2007. Removal of perchlorate from groundwater by the polyelectrolyte – enhanced ultrafiltration process. Desalination 204, 335 – 343.
• Hurley, K.D., Shapley, J.R., 2007. Efficient heterogeneous catalytic reduction of perchlorate in water. Environmental Science and Technology, 41, 2044 – 2049.
• Wang, D.M., Huang, C.P., 2008. Electrodualytically-assisted catalytic reduction (EDACR) of perchlorate in dilute aqueous solutions. Separation and Purification Technology, 59, 333 – 341.
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• Yu, X., Amrhein, C., Deshusses, M.A., Matsumoto, M.R., 2006. Perchlorate reduction by autotrophic bacteria in the presence of zero-valent iron. Environmental Science and Technology, 40, 1328 – 1334.
• Yu, X., Amrhein, C., Deshusses, M.A., Matsumoto, M.R., 2007. Perchlorate reduction by autotrophic bacteria attached to zerovalent iron in a flow-through reactor. Environmental Science and Technology, 41, 990 – 997.
• Huang, C.P., 2005. Removal of perchlorate from water and wastewater by catalytic hydrogen gas membrane systems. SERDP CP-1430.
• Huq, H.P., Yang, Y.S., Yang, J.W., 2007. Removal of perchlorate from groundwater by the polyelectrolyte – enhanced ultrafiltration process. Desalination 204, 335 – 343.
• Federal Remediation Technologies Roundtable (FRTR), 2005. Federal Remediation Technologies Reference Guide and Screening Manual, Version 4.0. February 1. http://www.frtr.gov/matrix2/top_page.html
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