Laurie Ekes, Environmental Chemical Corporation (ECC), PB 519 Gaffney Road, Otis ANGB, MA 02542, Tel: 508-563-9767, Fax: 508-563-7659, Email: LEkes@ecc.net 
Shouvik Gangopadhyay, Environmental Chemical Corporation (ECC), PB 519 Gaffney Road, Otis ANGB, MA 02542, Tel: 508-563-9767, Fax: 508-563-7659, Email: SGangopadhyay@ecc.net
Gregg Meyers, P.E, TDX, PB 519 Gaffney Road, Otis ANGB, MA 02542, Tel: 508-563-9767, Fax: 508-563-7659, Email: GMeyers@ecc.net
Ian T. Osgerby, PE, Ph.D., U.S. Army Corps of Engineers, New England District, 696 Virginia Road, Concord, Massachusetts 01742, Tel: 978-318-8631 Fax: 978-318-8663, Email: Ian.T.Osgerby@nae02.usace.army.mil
Paul Nixon, PE, Impact Area Groundwater Study Office, PB 565/567 West Outer Road, Otis ANGB, MA 02542, Tel: 508-968-5620, Fax: 508968-5286, Email: Paul.Nixon@MA.ngb.army.mil

Thermal desorption is a proven technology for the treatment of explosive compounds in soils.  However, the soil scoped for thermal treatment was also found to contain low levels of perchlorate contamination.  Thermal desorption has not been applied to perchlorate contaminated soils.  This presentation will present the approach taken to modify thermal treatment conditions for explosive contaminated soils to include treatment for perchlorate.  Initially, a bench scale study was conducted, at a research laboratory, to determine if thermal desorption was a viable treatment technology for perchlorate contaminated soil.  The bench scale study successfully demonstrated the effectiveness of thermal treatment of perchlorate and helped establish baseline treatment conditions.  Subsequently, pilot tests were conducted at a full-scale thermal treatment unit using site soil and clean sand spiked with known concentrations of perchlorate.  A total of twenty tests were conducted under different combinations of concentration levels and treatment temperatures.  These pilot tests allowed field proofing of the bench scale laboratory results and defined the process parameters needed for successful treatment.  The pilot tests revealed a reduction in treatment effectiveness at elevated soil concentrations, demonstrating a fixed percentage removal efficiency of perchlorate from soils.  During the pilot test period, matrix interferences issues affecting the analysis of perchlorate were investigated and resolved.  A proof of performance test was also conducted to establish the air permit compliance for explosive compounds and perchlorate, as well as other air emission constituents.  Process parameters continued to be monitored during full scale operations and were continually modified to increase the efficiency of remediation.  Approximately 40,000 tons of contaminated soils have been processed at a rate of approximately 750 tons per day.  Analytical results from the studies, tests and full scale operations will be presented demonstrating that thermal treatment is highly successful in the removal of explosives and perchlorate from soil. 

Perchlorate in Water: A Comparison of Methods 314.0 and 332.0

Scott McLean, James F. Occhialini, Arin Jones and James Todaro, Alpha Analytical Labs, Eight Walkup Dr., Westborough, MA 01581, Tel: 508-898-9220

Perchlorate is a natural and man-made chemical that has been used as an oxidizer in rocket fuel, munitions and fireworks since the 1950s.  It is known to disrupt thyroid function by inhibiting iodine uptake, thereby inhibiting the production of key thyroid hormones.  It is very soluble in water and therefore highly mobile.  Perchlorate has been detected in drinking water supply wells in several MA communities. In 2004, a drinking water MCL of 1 ppb was proposed by MADEP, consistent with the MCL proposed by EPA in 2002. While the CADHS set a notification limit of 6 ppb, NAS recently concluded that a level equivalent to 20 ppb might be more appropriate.   The current accepted method for low level analysis, EPA 314.0, utilizes an Ion Chromatograph fitted with a conductivity detector and a suppressor to reduce interference from background contaminants; however this method encounters problems in the presence of elevated sample conductivity.  An alternative method, EPA 332.0, has been developed to address these problems.  Method 332.0 utilizes an IC fitted with an MS or MS/MS.  The MS technology allows for the detection of perchlorate to sub ppb concentrations even in the presence of high concentrations of interferents.  In this paper the authors present method qualification data as well as real world sample data from both methods.  Comparison of real world data from samples with high conductivity will demonstrate the capability of Method 332.0 to accurately and precisely quantitate perchlorate at or below the current draft MCLs.

Lab and Field Studies of Low Concentrations of Perchlorate in Groundwater

Katherine Weeks, PE   AMEC Earth and Environmental, 239 Littleton Road, Suite 1B, Westford, Massachusetts 01886, Tel:  978-692-9090, Fax:  978-692-6633, Email: katherine.weeks@amec.com
Bernard Froman, AMEC Earth and Environmental, 239 Littleton Road, Suite 1B, Westford, Massachusetts 01886, Tel:  978-692-9090, Fax:  978-692-6633, Email: bernie.froman@amec.com
Bob Parette, The Pennsylvania State University, 212 Sackett Engineering Bldg., University Park, PA 16803, Tel:  814-865-4851, Fax:  814-863-7304, Email: rbp122@psu.edu 
Ian Osgerby, USACE/CENAE, 696 Virginia Road, Concord, MA  01742-2751, Tel:  978.318.8631, Fax:  978-318-8663, Email:  ian.t.osgerby@usace.army.mil    
Fred S. Cannon The Pennsylvania State University, 212 Sackett Engineering Bldg., University Park, PA 16803, Tel:  814-865-4851, Fax:  814-863-7304, Email: fcannon@psu.edu                    

Potential remediation processes for explosives and perchlorate-impacted groundwater at military bases are being evaluated on a fast track schedule.  Groundwater remediation treatability studies utilizing combined laboratory and field efforts were conducted in 2003 and 2004. The studies focused on ex situ remediation of perchlorate using several types of filter media, including granular activated carbon (standard GAC), GAC that has been tailored with a cationic monomer (tailored GAC), type I styrenic ion exchange (IX) resin and nitrate selective IX resin. Historically, military operations at the site have resulted in the groundwater impacts via leaching of propellants, explosives, and pyrotechnic (PEP) compounds. Perchlorate concentrations at the study sites ranged from 0.8 to 5.5 mg/L.

Ex-situ treatability studies were conducted with GAC and Tailored GAC on groundwater with concentrations of 0.8 to 1.5 mg/L perchlorate (Study 1) and 1.8 to 5.5 mg/L perchlorate (Study 2).  The studies used rapid small-scale column testing (RSSCT) conducted at Pennsylvania State University.  RSSCTs conducted per ASTM 6586-00 determined breakthrough behavior of a media via column tests utilizing similitude between media radius sizes. 

Ex-situ field scale studies were conducted at selected groundwater monitoring/extraction wells containing 0.8 10 1.5 mg/L perchlorate using standard GAC (Study 3), and containing 1.9 to 3.9 mg/L using type I styrenic IX resin, nitrate selective IX resin, and tailored GAC (Study 4). These studies determined breakthrough behavior under a 3.3 gpm flow rate per treatment vessel with an empty bed contact time of 5 minutes. The objectives for the studies were to demonstrate the ability to remediate groundwater in each operable unit to cleanup goals of less than 1 μg/L perchlorate. These studies were sufficiently robust to provide information to design and implement field-scale applications in the coming year.  Results show that IX resins, tailored GAC, and standard GAC are all effective in removing low concentrations of perchlorate from groundwater.  

Ex Situ Treatment of RDX and Perchlorate in Groundwater

Katherine Weeks, PE   AMEC Earth and Environmental, 239 Littleton Road, Suite 1B, Westford, Massachusetts 01886, Tel:  978-692-9090, Fax:  978-692-6633, Email: katherine.weeks@amec.com
Eric V. Johnson, AMEC Earth and Environmental, 239 Littleton Road, Suite 1B, Westford, Massachusetts 01886, Tel:  978-692-9090, Fax:  978-692-6633, Email: eric.v.johnson@amec.com
Scott Michalak, USACE/CENAE, 696 Virginia Road, Concord, MA  01742-2751, Tel:  978.318.8350, Fax:  978-318-8663, Email: scott.c.michalak@usace.army.mil           
Paul Nixon, Army Environmental Center, Impact Area Groundwater Study Program, 803 West Outer Road, Camp Edwards, MA, 02542, Tel:  508-968-5620, Fax:  508-968-5286, Email: Paul.Nixon@MA.ngb.army.mil

Remediation of explosives and perchlorate-impacted groundwater at a military base is being implemented on a fast track schedule, to meet rapid response action (RRA) regulatory requirements under the Safe Drinking Water Act.  Historically, operations at the site have resulted in the groundwater impacts via leaching of explosives and propellants.  Two RRA groundwater remediation systems were designed, constructed, and installed in 2004 to address these impacts to the sole source aquifer. The systems provide ex situ treatment of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), along with perchlorate, using granular activated carbon (GAC) and nitrate-selective ion exchange resin filter media. 

Influent groundwater concentrations at one system are less than 1 mg/L RDX and 2 to 6 mg/L perchlorate, with an influent flow of 100 gallons per minute (gpm).  Influent concentrations at the other system are 5 mg/L RDX and 30 to 40 mg/L perchlorate, with an influent flow of 220 gpm.  The systems are required to treat the groundwater to 0.25 mg/L RDX and 0.35 mg/L perchlorate.  In each system, groundwater is extracted from along the central axis of the groundwater plume and re-injected outside the plume boundary cross-gradient to and deeper than each extraction well.

Several challenging criteria were established for the treatment systems.  The design and construction were required to meet the RRA schedule.  The systems were required to be mobile treatment systems.  They were required to provide flexibility for treatment of multiple contaminants.  Specifically, the use of GAC is innovative as it has historically considered ineffective for removal of perchlorate.  These special design constraints limited the allowable size of the treatment vessels, which resulted in a shorter empty bed contact time (EBCT) than what is typically used for RDX and perchlorate treatment.  This shortened EBCT is feasible due to low levels of RDX, perchlorate, and other geochemical constituents present in groundwater at the site.

Perchlorate Reduction by Autotrophic Bacteria Supported on Zero-Valent Iron

Xueyuan Yu, Dept. of Chemical and Environmental Engineering, University of California, Riverside, Riverside, CA 92521, Tel: 951-827-2956, Fax: 951-827-5969, Email: xyu@engr.ucr.edu
Christopher Amrhein, Dept. of Environmental Sciences, University of California, Riverside, Riverside, CA 92521, Tel: 951-827-5196, Fax: 951-827-3993, Email: christopher.amrhein@ucr.edu
Marc A. Deshusses, Dept. of Chemical and Environmental Engineering, University of California, Riverside, Riverside, CA 92521, Tel: 951-827-2477, Fax: 951-827-5696, Email: mdeshuss@engr.ucr.edu
Mark R. Matsumoto, Dept. of Chemical and Environmental Engineering, University of California, Riverside, Riverside, CA 92521, Tel: 951-827-5318, Fax: 951-827-5696, Email: matsumot@engr.ucr.edu

Recently, the presence of perchlorate contaminated ground water has been a rising concern in the USA.  To treat perchlorate contaminated ground water, bioremediation is the preferred strategy as ClO₄^- is converted to chloride and eliminated from the environment.  H₂ is the favored energy source for the perchlorate degrading bacteria as it does not result in excess biomass growth and can be more cost-effective than organic compounds.  Biofouling is commonly encountered in laboratory and field tests when organic substrates are used.  As a remediation technology, zero-valent iron (ZVI) in permeable reactive barriers (PRBs) has shown great potential for the effective treatment of halogenated organic compounds, chromate, uranium, and other oxidized elements.  Unfortunately, ZVI has been shown to be ineffective in reducing ClO₄^-, in spite of the fact that the reaction is thermodynamically favorable.  In this research, laboratory scale experiments were employed to test the feasibility of a novel technology (ZVI-PRM) using zero-valent iron (ZVI) support perchlorate reducing microorganisms (PRM) to remove perchlorate from water.  In this process, H₂ released during corrosion of ZVI is used by the PRMs as an energy source and electron donor.  Batch and column experiments were used to demonstrate the efficacy of this process and to quantify factors affecting perchlorate reduction by a Dechloromonas sp. supported on granular ZVI.  In batch experiments, increasing degradation rates with a maximum reduction rate of 200 mg ClO₄^- /g biomass/hr was observed.  In flow through column experiments, with an influent concentration of 500 ppb, effluent perchlorate was below the detection limit at a liquid velocity of 0.17 to 5.57 m/day (HRT = 2.1 to 63 hrs).  No reduction of perchlorate was observed at an initial pH of 6 and 9, respectively.  The reduction of nitrate was preferred to perchlorate reduction by ZVI-PRM.

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