Title: Introduction Text: The Navy and Department of Defense (DoD) have invested over $60 million in the development, testing, and use of innovative perchlorate treatment technologies. NAVFAC Remedial Project Managers (RPMs) should be aware of the range of perchlorate treatment options available in order to evaluate and select the best approach for their site. This Web tool provides a brief background on several issues including perchlorate policy, chemistry, sources, and analytical methods. It also provides an overview of perchlorate treatment technologies and a review of biological and ion exchange treatment. NAVFAC and DoD sponsored projects related to the removal of perchlorate from groundwater are also highlighted.

Title: Policy Text: The Department of Navy (DON) released a new policy related to Perchlorate Sampling and Management in May 2006. The policy discusses the appropriate analytical methods and also outlines the management actions to be taken if perchlorate detections occur at a site. The policy indicates that DoD has established a level of concern for perchlorate of 24 parts-per-billion (ppb) until such time that state or federal standards are promulgated. This level of concern is based on the oral reference dose for perchlorate recommended by the National Academy of Sciences (NAS) and adopted by the U.S. Environmental Protection Agency (EPA). It states that Navy policy is "to sample all sites where there is a reasonable expectation that a perchlorate release has occurred as a result of Navy activities, including sites previously analyzed by EPA Method 314.0." More definitive analytical methods than EPA Method 314.0 have recently been developed. These methods employ mass spectrometry and will provide a higher level of confidence about the occurrence of perchlorate in various environmental media at a site. Additional information is provided in the companion DoD Perchlorate Handbook.

Title: Chemistry: Perchlorate Properties (1 of 2) Text: Perchlorate forms when solid salts composed of ammonium, potassium, or sodium perchlorate dissolve in water. Its chemical characteristics include low volatility, low sorptivity, and high water solubility. Perchlorate is very chemically stable under aerobic groundwater conditions and can persist in the environment for decades. These properties all govern the fate and transport of perchlorate in groundwater and may lead to relatively large dissolved phase plumes at perchlorate-impacted sites.

Title: Low Volatility Text: Low volatility means that a chemical does not evaporate readily at normal temperature and pressures.

Title: Low Sorptivity Text: Low sorptivity means that a chemical tends not to be attracted to particles such as soil or organics.

Title: High Water Solubility Text: High water solubility means that a chemical readily dissolves in water.

Title: Chemistry: Perchlorate Sources (2 of 2) Text: Perchlorate is used in a variety of defense and commercial applications. Click here for a list of DoD munitions, munitions components, and training devices that may have contained perchlorate. Perchlorate releases may have occurred at sites where the following activities took place: The manufacture, storage, or disposal of perchlorate salts, perchlorate-containing propellants, rocket fuels, explosives, perchlorate containing munitions, munitions components, or training devices. These activities have occurred primarily at ammunition plants, arsenals, and depots. Research, development, testing, and use of perchlorate containing propellants, rocket fuels, explosives, munitions, or munitions components. Training with perchlorate containing munitions or training simulators. The DoD Perchlorate Handbook notes that "the simple fact that one or more of these activities occurred, however, should not be interpreted as evidence that perchlorate has been released." Perchlorate is also found in commercial products and releases have occurred at other non-DoD sites. Click here for a list of potential non-DoD sources. The Interstate Technology and Regulatory Council (ITRC) Perchlorate Overview document also has information on sources of perchlorate in the environment.

Title: DoD Perchlorate Sources Text: Solid fuel rockets Sea mines Torpedo warheads Smoke-generating compounds Signal flares Parachute flares Star rounds for pistols (illumination rounds) Thermite-type incendiaries Tracer rounds Incendiary bombs Fuzes Jet-assisted takeoff (JATO) devices Training simulators

Title: Non-DoD Perchlorate Sources Text: Commercial blasting (for construction) with perchlorate-containing explosives Use of perchloric acid in manufacturing processes Perchlorate-containing fertilizer Perchlorate-containing sodium chlorate used as a herbicide Commercial manufacture of perchlorate salts or perchlorate-containing items (e.g., pyrotechnics and flares)

Title: Analytical Methods Text: The DoD Perchlorate Handbook describes how to select qualified analytical laboratories and analytical methods for perchlorate. The analytical requirements for perchlorate testing will vary depending on the regulatory drivers and RPMs should secure approval from the regulatory authority for the use of the appropriate method. The selected method must be able to meet the specified method reporting limit (MRL) in the matrix of concern. Only methods employing mass spectrometry (MS) are to be used for environmental restoration/cleanup or range assessment projects. This table summarizes the recommended methods for perchlorate analysis. MS methods provide more definitive results and much lower reporting limits compared to previous methods that used ion chromatography (IC) alone such as EPA Method 314.0.

Title: Mass Spectrometry Text: Uses an instrument to identify the type and quantity of elements in a chemical substance by their mass and charge.

Title: Treatment Technologies Text: The use of conventional water treatment technologies has proven to be largely ineffective for perchlorate removal because of its low reactivity, low volatility, and high solubility. Therefore, substantial effort has been made to develop and test more effective treatment methods for perchlorate. Many different technologies have been tested at both the pilot-scale and full-scale. Roll over the figure to see a specific list of these treatment technologies. The remainder of this tool focuses on biological treatment and ion exchange because these are currently the leading economically viable groundwater treatment technologies for perchlorate.

Title: Treatment Technologies Text: Continuously Stirred Reactors Packed Bed Reactors Fluidized Bed Reactors Other Reactor Types

Title: Treatment Technologies Text: Passive Delivery Systems Semi Passive Delivery Systems Active Delivery Systems Phytoremediation

Title: Treatment Technologies Text: Weak Base Anion Exchange Strong Base Anion Exchange Bifunctional Resin Ion Exchange Reverse Osmosis Tailored Granular Activated Carbon Adsorption

Title: Treatment Technologies Text: Chemical Reduction Catalytic Reduction Electro/Photochemical Reduction Precipitation

Title: Treatment Technologies Text: Supercritical Water Oxidation Non-Catalytic, Hydrothermal Treatment Low Pressure Thermal Treatment

Title: Biological Treatment Overview Text: Biological treatment of perchlorate in groundwater can proceed relatively rapidly under the right conditions. The microbes require the presence of sufficient electron donor such as ethanol to stimulate perchlorate biodegradation. Nutrients such as nitrogen and phosphorous are also needed to sustain adequate microbial growth. These amendments can be added to enhance the biodegradation of perchlorate either in situ (i.e., below ground) or ex situ (i.e., above ground). The introduction of these amendments then allows the microbes to grow and produce enzymes. The enzymes lower the activation energy needed to reduce perchlorate to chloride and oxygen. Without an electron donor, the perchlorate molecule is typically very stable and will not be readily degraded by microbes under aerobic groundwater conditions.

Title: Definition Text: Reduction is a process in which a substance gains one or more electrons.

Title: Definition Text: Activation energy is the minimum amount of energy input needed for a reaction to occur.

Title: In Situ Biological Treatment (1 of 2) Text: The objective of in situ biological treatment is to engineer the optimal conditions in the subsurface to promote perchlorate biodegradation. This process can be limited under normal conditions due to low pH, insufficient carbon for microbial growth, high dissolved oxygen levels, and/or the presence of nitrate because it is preferentially degraded. These limitations can be overcome through the addition of an adequate supply of electron donor to the subsurface or with pH buffering. The two most important considerations for in situ treatment are the selection of an appropriate amendment (e.g. electron donor) and the method used to deliver the amendment into the subsurface.

Title: Solution Text: An electron donor is added to the subsurface to promote in situ biodegradation.

Title: Injection Well Text: The electron donor is delivered to the subsurface via an injection well or another method.

Title: In Situ Biological Treatment (2 of 2) Text: The following are the primary advantages and limitations associated with in situ biological treatment: Advantages Hot spot treatment removes long-term source to groundwater Use as biobarrier to prevent off-site migration Destroys perchlorate and does not just concentrate it into a brine as with ex situ physical treatment methods Can be configured to reduce aboveground footprint May involve less capital and operation and maintenance (O&M) costs compared to ex situ treatment options May also promote the biodegradation of chlorinated compounds such as PCE and TCE Limitations Number of field-scale projects limited Best suited to well-defined and shallow source areas Biofouling of injection wells can cause significant O&M issues Inefficient donor delivery can lead to little or no in situ biodegradation Low pH, high salinity, and the presence of other chemicals such as nitrate can influence the rate and extent of perchlorate degradation Can adversely impact groundwater quality such as metals mobilization, sulfide release, and methane production Regulatory approval may be needed for amendment injection

Title: Amendment Selection Text: Several amendments or electron donor sources have been used for perchlorate biodegradation including alcohols, fatty acids, edible oils, sugars, and food wastes. The selection of the most appropriate amendment is typically based on the relative biodegradation rates of perchlorate measured in laboratory microcosm studies. For example, a DoD SERDP study evaluated several different types of electron donor amendments for perchlorate biodegradation. Each amendment was tested in a laboratory microcosm using groundwater from several DoD and other sites. The results of one microcosm study from the SERDP study are shown here from the Naval Surface Warfare Center (NSWC) Indian Head Division (IHDIV) in Maryland. Click the "Next Graphic" button to view a graph of perchlorate removal over time with four different amendments. The study demonstrated that after pH adjustment of the site groundwater rapid biodegradation of perchlorate could be achieved. The best results were seen in the acetate and hydrogen microcosms with perchlorate biodegradation from 125 mg/L to non-detect in just over 10 days.

Title: Delivery Methods Text: Several methods have been proposed for the delivery of electron donor to the subsurface including passive, semi-passive, and active injection scenarios. Click on an injection method schematic for more information. ESTCP is currently conducting a project to determine the most cost-effective delivery mechanisms for the in situ biodegradation of perchlorate. Click here for more information on several different projects to treat perchlorate.

Title: Passive Delivery Methods Text: Passive delivery methods rely upon the natural groundwater gradient and dissolution and dispersion to deliver the electron donor into the subsurface. Passive strategies include permeable reactive barriers (PRBs) or the placement of a slow release compound (e.g., vegetable oil or polylactate) into an array of unpumped wells. Passive methods are best suited to sites with relatively shallow groundwater plumes due to practical limitations on the construction of effective barriers at depth. For example, with groundwater at only 2 to 10 ft below ground surface, a full-scale PRB was found to be an economical approach to treat elevated perchlorate levels in groundwater at the Naval Weapons Industrial Reserve Plant (NWIRP) in Texas.

Title: Semi-Passive Delivery Methods Text: Semi-passive delivery strategies consist primarily of injection only configurations. These methods rely upon continuous or periodic forced injection of electron donor into one well or an array of wells. Semi-passive systems are best suited to the reduction of contaminant levels in low-concentration plumes and/or to act as a “polishing step” for other remediation methods. Semi-passive systems do not provide hydraulic containment and may produce localized mounding depending upon the injection strategy.

Title: Active Delivery Methods Text: Active methods involve both injection and extraction to promote mixing and delivery of the electron donor in the aquifer. The most common active delivery method is dual vertical well recirculation as shown in the figure. Other delivery methods include dual horizontal well recirculation and single vertical well recirculation. Active delivery mechanisms are best suited for treating high-concentration plumes or source areas and can also be designed to provide for hydraulic containment. This delivery approach was used to treat perchlorate impacted groundwater at the Naval Surface Warfare Center (NSWC) Indian Head Division (IHDIV) in Maryland.

Title: Passive In Situ Biotreatment at NWIRP Text: A PRB is an example of a passive delivery mechanism. Both pilot-scale PRBs and a full-scale PRB network have been installed at the Naval Weapons Industrial Reserve Plant (NWIRP) in McGregor, TX. The NWIRP McGregor site was used to manufacture and test rocket motor propulsion systems until 1995. Perchlorate concentrations as high as 91,000 ppb were detected at the site during early site investigations. The perchlorate plume is located primarily in the upper portions of an unconfined 5-ft to 35-ft thick fractured limestone aquifer. The depth to groundwater varies seasonally from depths of 2 to 10 ft below ground surface. The PRBs at NWIRP McGregor contain organic material such as compost and soybean oil that acts as an electron donor source for microbes to reduce perchlorate as groundwater moves through the barrier. This site is well-suited to a PRB application because the impacted aquifer is relatively shallow.

Title: Pilot-Scale PRBs for Perchlorate Treatment Text: Several areas at NWIRP have addressed perchlorate releases. At Area F, five pilot-scale PRBs were installed to assess biobarrier construction issues. The pilot-scale barriers ranged from 75 ft to 100 ft in length and were approximately 12 feet deep. The primary objectives of the study were to investigate the longevity of the biobarrier media, the nature of the organic carbon distribution, and the optimal biobarrier media mix. Other site-specific issues of concern were the impact of the fractured limestone on barrier hydraulic performance and the ability to co-treat perchlorate and trichloroethene in groundwater. As shown in Figure 1, several combinations of electron donors were tested including both solid and soluble forms of organic carbon. The amendments tested include compost, wood chips, acetic acid, and vegetable oil. Click through the figures to see sample results from the pilot-scale PRBs. Figures 2 and 3 show the reduction of perchlorate downgradient of Trenches 1 and 2. Figures 4 and 5 show the total organic carbon concentrations at these trenches with time. Based on this and other data, it was determined that carbon regeneration (e.g. soybean oil application) would be required every one to two years.

Title: Full-Scale PRB for Perchlorate Treatment Text: Based on the success of the pilot study at NWIRP, a full-scale PRB system was constructed in late 2002 to address the off-site migration of the perchlorate plume. The full-scale PRB was constructed in the vicinity of Area S, the Explosives Classification and Disposal Area, which was the official burning ground for off-specification ammonium perchlorate. A total of 3,500 linear feet of trench was installed at Area S in seven trench segments. The segments were installed in the downgradient plume direction approximately 1,000 ft apart. Each trench was backfilled with a mixture of gravel (70%), mushroom compost (20%), and soybean oil-soaked woodchips (10%). Over 4,200 tons of material were used to backfill the trenches. This video shows the changes in the perchlorate plume from 1999 before the barrier installation through 2003 several months after the barrier installation. The later portion of the video shows the dramatic impact of the barriers on the perchlorate plume at the leading edge. Project monitoring conducted to date indicates that the perchlorate concentrations continue to decrease to non-detectable levels in groundwater that has passed through the PRB system. NAVFAC has estimated an overall capital cost avoidance of $3 million as a result of using a PRB versus a conventional pump and treat system at this site.

Title: Active Recirculation Case Study at IHDIV Text: Active recirculation for the in situ treatment of perchlorate in groundwater was demonstrated at NSWC IHDIV in Maryland in conjunction with the Naval Ordnance Safety and Security Activity (NOSSA) and SERDP. Groundwater at the site contained perchlorate as a result of historic waste disposal practices at a "Hogout" facility for the cleaning and preparation of ejection seat motors. An active recirculation system shown here was used to circulate an electron donor solution within the aquifer to promote the in situ biodegradation of perchlorate. The site has a shallow groundwater table at 10 to 14 ft below ground surface which makes it suitable for an in situ treatment approach. The target treatment zone was a silty/sandy aquifer zone above a well-pronounced coarse gravel layer and bottom clay layer. Click through the figures to see the treatment system set-up at IHDIV. The major system components included two injection wells, two extraction wells, an injection skid, a tank for the 60% sodium lactate electron donor solution, and a tank for the 6.7% carbonate/bicarbonate buffer solution.

Title: Active Recirculation Case Study Results at IHDIV Text: The buffer and electron donor circulation began in June 2002. During the first 15 weeks of operation, approximately 20,000 gallons of groundwater were recirculated with the addition of 600 gallons of buffer solution and 25 gallons of sodium lactate. The buffer solution was added based on the results of microcosm studies which indicated that the acidic groundwater conditions (pH of 4.3) were inhibiting microbial growth at the site. The recirculation system was demonstrated to have effectively delivered buffer and electron donor throughout the test plot. Lactate was measured in all of the test plot monitoring wells within three weeks of system startup. Nitrate levels were reduced to below detection limit in seven out of nine test plot monitoring wells after 7 weeks of system operation. As shown here, perchlorate levels were reduced by greater than 95% in eight out of nine test plot monitoring wells and by 43% in the remaining well. The control plot showed no appreciable increase in pH and no significant decline in perchlorate or nitrate levels. Overall, the study results showed that perchlorate and nitrate biodegradation occurred relatively rapidly after amendment addition and that buffer addition is viable in acidic aquifers. Click here for the test report on this project.

Title: Ex Situ Biological Treatment (1 of 2) Text: Ex situ biological treatment involves extracting groundwater from the subsurface and pumping it through a reactor containing a large population of microbes. A steady supply of electron donor is pumped into the reactor to support microbial growth and the subsequent reduction of perchlorate. Roll over the figure for more information on the types of bioreactor configurations and amendments used.

Title: Ex Situ Bioreactors Text: Several types of bioreactor configurations are available, including continuously stirred tank reactors (CSTRs), packed bed reactors (PBRs), fluidized bed reactors (FBRs), and others such as hollow fiber membrane reactors. Several types of electron donors have been tested for use in bioreactors including acetate, ethanol, methanol, hydrogen gas, yeast extract, and food processing wastes.

Title: Ex Situ Biological Treatment (2 of 2) Text: The following are the primary advantages and limitations associated with ex situ biological treatment: Advantages Tested at both pilot-scale and full-scale Destroys perchlorate instead of concentrating it into a brine as with ex situ physical treatment Several bioreactor configurations have been tested at full-scale and successfully commercialized Typically less expensive in terms of O&M costs compared to physical/chemical methods Typically generates less hazardous waste than physical/chemical methods Limitations Upsets can occur from suboptimal electron donor dosing, pH changes, or other conditions Loss of biological activity could interrupt operation for several days Less conventional for drinking water applications

Title: Continuously Stirred Tank Reactors (CSTRs) Text: CSTRs have an active biomass that is kept in suspension by mechanical mixing in a liquid-filled tank. The continuous mixing action provides for more uniform biodegradation throughout the reactor. CSTRs are well suited to the treatment of low flowrates and highly concentrated perchlorate wastes. CSTRs are unsuitable for groundwater treatment applications with high flowrates above 1,000 gpm and low concentrations. The residence times for these types of bioreactors are typically 2 to 4 hours.

Title: Packed Bed Reactors (PBRs) Text: Biomass in a PBR attaches and grows on media placed inside the reactor. The media is selected to provide a large surface area and to facilitate flow to obtain the necessary hydraulic residence time. The packed bed media also reduces the need for downstream filtration. However, PBRs are reported to have a tendency for channeling and clogging. During long-term operation, the reactor will require periodic backwashing to prevent excessive headloss through the bed.

Title: Ex Situ Biological Treatment Text: The purpose of the media is to provide a surface for the microbes to attach to and grow. Filter media can consist of sand, granular activated carbon, plastic rings, Celite, or other materials. Celite is a pelletized natural product consisting of a light-colored porous rock composed of the shells of diatoms.

Title: Fluidized Bed Reactors (FBRs) Text: FBRs are also attached growth reactors. The term fluidization means that the media particles are suspended and not in contact with other particles. It increases the specific surface area available for microbial growth and therefore increases the efficiency of perchlorate reduction per unit volume of the reactor. This advantage can be used to size smaller bioreactors and/or to reduce hydraulic residence times, while still obtaining effective perchlorate reduction. To date, FBRs are the most commonly implemented reactor type for perchlorate treatment at full-scale.

Title: Ex Situ Biological Treatment Text: Granular activated carbon or sand is used as the filter media.

Title: Ex Situ Biological Treatment Text: A network of nozzles ensures a uniform upflow velocity across the bottom of the bed and fluidizes the media.

Title: Ex Situ Biological Treatment Text: The total flow consists of both the recycle flow of treated water and the forward flow of untreated groundwater.

Title: Ex Situ Biological Treatment Text: The lowest density particles with the highest attached biomass move up to the top of the FBR. A biomass control system is used at the top to remove the excess biomass and to maintain the target bed height.

Title: Other Bioreactor Configurations Text: Several novel bioreactor types have been proposed including microbial mat and algae bioreactors. In addition, the use of hydrogen-based systems has been evaluated at the pilot-scale such as gas-lift reactors with pumice filter media and a hollow fiber membrane biofilm reactor.

Title: FBR Case Study LHAAP, TX (1 of 2) Text: A 50-gpm FBR system was installed at the Longhorn Army Ammunition Plant (LHAAP) in Texas to remove perchlorate from groundwater extracted by a pre-existing pump and treat system. The pump and treat system had been originally designed to treat only volatile organic compounds (VOCs) and metals. First, a laboratory treatability study was carried out to provide key parameters for full-scale FBR design and to confirm the effectiveness of biological treatment with site groundwater. As a result of the lab study, acetic acid was selected as the electron donor to promote perchlorate biodegradation. The full-scale FBR system consisted primarily of the reactor vessel (5 ft in diameter and 21 ft tall), fluidization and influent pumps, flow distribution system, chemical feed system, two biomass separation systems to control bed height from the top, and a third in-bed media cleaning system. The influent perchlorate levels ranged up to 33 ppm and the effluent perchlorate levels have been consistently below the detection limit of less than 4 ppb.

Title: FBR Case Study NWIRP McGregor, TX (2 of 2) Text: The 400 gpm system consists of a 7.5-foot-diameter, 21-foot-tall, stainless-steel FBR. Granular activated carbon media is used for biomass development. Effluent from the FBR is discharged either directly to a nearby tributary via Texas Pollution Discharge Elimination System (TPDES) Outfall 001 or to a storage unit. Since its inception in late January 2002, the FBR has removed perchlorate concentrations from up to 3.1 ppm to below detection limits at less than 2 ppb. Click here to view a table of operating information.

Title: Text:

Title: Ion Exchange (1 of 3) Text: Ion exchange is also an ex situ treatment technology, which involves extracting groundwater from the subsurface and pumping it through a reactor. Ion exchange removes ions from solution through sorption onto a resin. The resin eventually becomes saturated and must be regenerated. For perchlorate treatment, it is typically more cost effective to use disposable resins that can be incinerated rather than to pay to treat the regenerant brine. Several types of ion exchange resins can be used for perchlorate removal including weak base anion (WBA), strong base anion (SBA), and bifunctional resins.

Title: Ion Exchange (2 of 3) Text: The goal of resin selection for perchlorate removal is to identify a resin that is both highly selective for perchlorate, but is still easily regenerated. These are somewhat competing objectives because the more selective the resin, the more difficult it will be to remove the perchlorate during regeneration. As contaminated groundwater is passed through the resin, perchlorate and other anions such as sulfate, nitrate, and bicarbonate are sorbed to the resin. The chloride is then released into the effluent stream. The resin eventually becomes saturated with perchlorate and the other anions and must be regenerated. In the regeneration step, a sodium chloride brine or other solution is passed through the spent resin and displaces the adsorbed perchlorate and other anions from the resin. The perchlorate and other anions that are transferred into the brine solution must be treated before disposal. A single resin can be regenerated several times before it is spent. Ion exchange concentrates, but does not destroy perchlorate. This leads to several challenges related to brine generation, treatment, and disposal. The waste brine from ion exchange is often very difficult to treat because it can contain very high perchlorate concentrations, up to 6 wt% salts, and caustic components. For this reason, the use of disposable resins without regeneration may be more economical.

Title: Ion Exchange (3 of 3) Text: The following are the primary advantages and limitations associated with ion exchange treatment: Advantages Tested at both pilot-scale and full-scale Commercially available technology Able to meet low perchlorate levels in effluent Physical treatment methods exhibit more stable operations than biological methods More widely accepted for drinking water applications Limitations O&M costs are typically high versus biological methods Not all resins are highly selective for perchlorate Other anions (e.g., nitrate, sulfate) may interfere with removal Brine treatment and disposal issues limit cost-effectiveness

Title: Bifunctional Resin Case Study at Edwards AFB, CA Text: A new type of bifunctional resin has been demonstrated to be five times more efficient at removing perchlorate than conventional anion exchange resin. This type of resin was developed by Oak Ridge National Laboratory (ORNL) and has recently become commercially available. The first pilot-scale test of this bifunctional resin for perchlorate removal was conducted at Edwards Air Force Base (AFB) in California and subsequently a full-scale system pictured here was installed and began treating groundwater in May 2003.

Title: Bifunctional Resin Case Study at Edwards AFB, CA Text: The capital cost of the project was approximately $800,000 for the 35 gpm bifunctional resin ion exchange system. With influent perchlorate levels at 400 ppb, it achieved effluent perchlorate levels below detectable limits. Through June 2004, the bifunctional resin system had treated 9.3 million gallons of groundwater and removed 32.3 lbs of perchlorate. In addition, ORNL demonstrated that the spent bifunctional resin bed could be successfully regenerated using tetrachloroferrate in a ferric chloride solution. Almost 100% of the sorbed perchlorate was recovered from the bifunctional resin with two bed volumes of regenerant solution. The first breakthrough of the resin bed at the site occurred in December 2003 and the system was regenerated in January 2003. An innovative perchlorate destruction process unit was also tested for its ability to breakdown the perchlorate in the regenerant solution into chloride and water. Because of its high affinity for perchlorate, a bifunctional resin system could be operated with a higher flowrate and/or a smaller bed volume compared to a conventional ion exchange system. Depending on water quality at a given site, the higher cost of a perchlorate-specific resin may be offset by operational savings due to longer resin life and/or reduced amounts of regenerant effluent.

Title: Other Perchlorate Treatment Technologies Text: There are several other physical, chemical, and thermal treatment technologies for perchlorate in groundwater. Physical Treatment Technologies. In addition to ion exchange, other potential physical treatment methods include various membrane processes and tailored granular activated carbon (GAC) adsorption. Membrane processes include treatment techniques such as reverse osmosis (RO), nanofiltration (NF), and electrodialysis (ED). All of these processes rely upon a semiporous membrane that lets water pass through, but prevents dissolved salts from penetrating the membrane. RO and NF have been reported to achieve more than 80% removal of perchlorate from process streams. With all membrane processes, the perchlorate removed is not destroyed, but collected and concentrated in a waste brine. Tailored GAC may be a future technology to remove perchlorate from existing pump and treat operations. Chemical Treatment Technologies. Potential chemical treatment methods reported in the literature for perchlorate include chemical reduction, catalytic reduction, electrochemical reduction, photochemical reduction, and precipitation. Catalysts can be used to overcome the high activation energy needed to effect perchlorate reduction. Several different types of catalysts have been tested in the scientific literature for their ability to promote the destruction of perchlorate to chloride and water. The types of catalysts tested include nickel, palladium, platinum, ruthenium, and titanium. There are several drawbacks to their use including the cost of expensive precious metals and the potential need for effluent pre-treatment to avoid catalyst fouling. Although catalysts have been employed at the field-scale to treat ion exchange brines containing perchlorate, it is unclear whether catalysts would be cost-effective as a stand-alone technology. Catalysts may be more cost effective when paired with a technology such as ion exchange or reverse osmosis that can concentrate the perchlorate influent stream therefore reducing the volume of water that must be treated in the catalytic unit. Thermal Treatment Technologies. The thermal destruction of perchlorate in solution has also been studied in the laboratory using high temperature, high pressure techniques such as super-critical water oxidation.

Title: Summary Text: The following observations can be made about perchlorate treatment technologies: Many different treatment technologies have been tested, but the leading economically viable technologies are biological and ion exchange treatment. The primary issue for in situ bioremediation is the effective delivery of amendments to the subsurface in order to achieve adequate electron donor distribution. Adequate electron donor distribution can be difficult to achieve at sites with very heterogeneous or complex soils or with deeper contamination. The full-scale use of ex situ bioreactors is feasible due to their effectiveness and commercial development status. However, biological treatment is sensitive to electron donor dosing, pH changes, or variable influent conditions. Ion exchange is a more conventional technology for producing potable water and perchlorate-specific resins are commercially available. However, the feasibility and cost of brine treatment and/or resin disposal must be carefully evaluated.

Title: References Text: For more information, check out the following documents and/or links: Policy and Guidance DON Policy on Perchlorate Sampling and Management DoD Perchlorate Handbook General Information DoD Perchlorate Work Group Interstate Technology and Regulatory Council Perchlorate Team Defense Environmental Information EXchange (DENIX) Perchlorate Page AFCEE Perchlorate Page Sampling and Analysis Information Joint IDQTF/DoD EDQW Roundtable on the Analysis of Perchlorate in Environmental Samples Treatment Technologies Perchlorate: Overview of Issues, Status, and Remedial Options U.S. EPA CLU-IN Contaminant Focus: Perchlorate Treatment Technologies U.S. EPA Perchlorate Treatment Technology Update

Title: Contact Information Text: For more information about the Perchlorate Web Tool, please contact: T2 NFESC POC (805) 982-1656 or Perchlorate NFESC POC (805) 982-1795 PRTH_NFESCT2@navy.mil