Perchlorate is used as an oxidizer component in solid propellant for rockets, missiles, and pyrotechnics. Non-military anthropogenic and natural sources also have been documented. The high solubility of perchlorate coupled with its chemical stability in water leads to expansive plumes. These same chemical properties make perchlorate contamination difficult to remediate by conventional physical-chemical water treatment methods. The U.S. Environmental Protection Agency (EPA) and various states are proposing stringent cleanup levels for perchlorate. As such, perchlorate represents a potential liability for the Department of Defense (DoD) in the billions of dollars.

Monograph on In Situ Bioremediation of Perchlorate in Groundwater Now Available SERDP and ESTCP are pleased to announce the release of In Situ Bioremediation of Perchlorate in Groundwater, the first volume in an Environmental Restoration Monograph Series. While significant progress has been made in the development of innovative and more cost-effective environmental remediation technologies, efforts are needed to facilitate broader use of these technologies by government and industry. This monograph will serve as a reference tool for remediation professionals to effectively apply in situ bioremediation of perchlorate in groundwater by providing a critical review of the past decade of intensive research, development, and technology demonstrations. To obtain a copy, visit the Springer site.

The Strategic Environmental Research and Development Program (SERDP) and the Environmental Security Technology Certification Program (ESTCP), DoD’s environmental technology programs, adopted a proactive approach to developing cleanup technologies for perchlorate beginning in 1998. These commercialized technologies are now being demonstrated at dozens of field sites across DoD and are gaining regulatory acceptance. SERDP and ESTCP have worked to develop an integrated program that holistically addresses the Research, Development, Test, and Evaluation (RDT&E) needs of perchlorate (see table below). In addition to traditional cleanup, this program encompasses DoD’s responsibility and vulnerability given numerous sources of perchlorate, alternatives to perchlorate as a long-term solution, and the toxicology of perchlorate to ecological receptors. SERDP and ESTCP's holistic approach to perchlorate is providing DoD with a suite of technologies to remediate existing contamination and to address future practices and liability. These technologies are expected to result in significant cost savings.

Brief descriptions of SERDP and ESTCP’s investments to manage the environmental impact of perchlorate follow. For additional information on these and other Ongoing Initiatives, visit Research Projects at www.serdp.org and Technologies at www.estcp.org.

In Situ Remediation of Groundwater
Demonstrations under ESTCP for in situ remediation of perchlorate-contaminated groundwater have focused on investigating various design options for implementing bioremediation. Specific design options are shown below. In addition, the potential for monitored natural attenuation also is being evaluated.

• “Active” In Situ Bioremediation with Capture and Reinjection of Amended Groundwater
• “Semi-Passive” In Situ Bioremediation with Batch Injection of Electron Donors
• In Situ Bioremediation Using Horizontal Flow Treatment Wells
• Permeable Reactive Barrier with Emulsified Edible Oil

In Situ Remediation of Vadose Zone Soils
ESTCP is demonstrating liquid electron donors and gaseous electron donors.

Ex Situ Wellhead Treatment for Drinking Water
Through ESTCP support, several wellhead treatment technologies are being demonstrated in the Rialto-Colton Basin, California. Technologies include:

• Weak Base Anion Resin with Zero Discharge of Regenerant Solution
• Perchlorate-Selective, Ion Exchange Resin Using a Single-Vessel Design
• Surfactant-Tailored Granular Activated Carbon
• Ion Exchange Regeneration
• Membrane Biofilm Reactor Coupled with Downstream Ultrafiltration
• Fluidized Bed Bioreactor
• Direct Fixed-Bed Bioreactor
• Bioreactor Utilizing Zero Valent Iron

Through SERDP support, researchers also are developing the next generation of technology to treat drinking water, including electrochemical processes.

Documenting Perchlorate Sources

SERDP and ESTCP are supporting the identification, characterization, and evaluation of natural, non-military, and military sources of perchlorate. The demonstration and validation of forensic tools to differentiate perchlorate sources also is ongoing.

Measurement of Perchlorate in the Environment
Research is ongoing under SERDP to develop new methods for identifying and quantifying perchlorate in the environment.  Current projects are investigating enzymatic bioassays, a  screening-level chemical assay, and identification of functional gene biomarkers.

Alternatives to Perchlorate
SERDP and ESTCP are actively investigating alternatives to perchlorate for red and green colored signal flares, solid rocket propellants, and incendiary mixes and pyrotechnics.

Eco-Toxicology
SERDP has funded numerous laboratory and field studies on the effect of perchlorate to amphibians, fish, invertebrates, birds, and small mammals in support of the EPA’s ecological risk assessment.

Technical Report on Alternative Causes of Widespread, Low Concentration Perchlorate Impacts to Groundwater (SERDP ER-1429), GeoSyntec Consultants, Inc.

Protocol for Enhanced In Situ Bioremediation Using Emulsified Vegetable Oil (ESTCP ER-0221), Solutions Industrial & Environmental Services, Inc.

Borden, R.C. 2007. Concurrent bioremediation of perchlorate and 1,1,1-trichloroethane in an emulsified oil barrier. Journal of Contaminant Hydrology 94 (1-2): 13-33.

Gu, B. and J.C. Coates (Eds.). 2006. Perchlorate: Environmental Occurrence, Interactions and Treatment. Springer Science+Business Media, Inc., New York.

Hatzinger, P.B. 2005. Perchlorate biodegradation for water treatment. Environmental Science and Technology 39(11): 239A-247A.

Kendall, R.J. and P.N. Smith (Eds.). 2006. Perchlorate Ecotoxicology. SETAC Press.

Rao, B., T.A. Anderson, G.J. Orris, K.A. Rainwater, S. Rajagopalan, R.M. Sandvig, B.R. Scanlon, D.A. Stonestrom, M.A. Walvoord, and W.A. Jackson. 2007. Widespread natural perchlorate in unsaturated zones of dry regions. Environmental Science and Technology 41(33): 4487-4832.

Sturchio, N.C., J.K. Bohlke, A.D. Beloso, Jr., S.H. Streger, L.J. Heraty, and P.B. Hatzinger. 2007. Oxygen and Chlorine Isotopic Fractionation During Perchlorate Biodegradation: Laboratory Results and Implications for Forensics and Natural Attenuation Studies. Environmental Science and Technology 41: 2796-2802.

DoD Materials of Emerging Regulatory Interest Team (MERIT)

Interstate Technology & Regulatory Council: Perchlorate Team