Bioremediation

Map of the NAWC In Situ Test Facility. Image credit: courtesy of Allen Shapiro, USGS Image Gallery

The Naval Air Warfare Center (NAWC) was a U.S. Navy jet engine testing facility for military aircraft from the mid-1950’s until the late 1990’s. Activities at the facility have caused tricholoethlylene (TCE), jet fuel, and other chemicals to leak into the subsurface which is a fractured-rock aquifer. A project within the USGS toxic substances hydrology program is ongoing at this site:

Chlorinated Solvents in Fractured Sedimentary Rock - Naval Air Warfare Center (NAWC) Research Site, West Trenton, NJ

Research is underway to evaluate Pump-and-Treat, monitored Natural Attenuation, and Enhanced Bioaugmentation in the In situ test facility at the NAWC site, which is an area within the NAWC site with historically high TCE concentrations in bedrock boreholes.

The Voytek Microbiology lab has been monitoring microbial community structure before and during bioaugmentation. We characterized the microbial community in the transect from 36BR to 15BR (and including 73BR, 71BR and 70BR) at the NAWC In Situ Test Facility at 4 time points before a bioaugmentation experiment adding KB1 (dechlorinating consortium from Geosyntec) and EOS electron donor, and have been monitoring the same microbial populations since this bioaugmentation experiment began. This served to help evaluate the natural community structure and potential for biodegradation, and to provide a baseline in order to monitor progress of the bioaugmentation experiment. Groundwater samples were taken at 4 times between March and August 2008. The bioaugmentation experiment began Oct 15, 2008, and groundwater samples were taken several times in October, and again Nov 2008, and Dec 2008 and February 2009. Monitoring is ongoing.

Photograph of the NAWC In Situ Test Facility. Image credit: courtesy of Allen Shapiro, USGS

Microorganisms capable of dechlorinating are present at some sites within the In situ Test Facility pre-bioaugmentation, but not at concentrations necessary for effective TCE degradation. Post bioaugmentation, the effect of bioaugmentation can be seen by several order of magnitude increases of dechlorinators at the injection site and other sites within the In Situ Test Facility.

For more information contact Julie Kirshtein, Voytek Microbiology.

See also Water Quality: Aquifers >>

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WBC-2 microbial consortium. Photo credit: Geosyntec Consultants

The Microbiology and Molecular Ecology group (Mary Voytek, Reston,VA), in cooperation with the USGS Maryland District office (Michelle Lorah), is examining the fate of chlorinated hydrocarbons, formed during munitions production, which contaminated the ground water and wetlands at Aberdeen Proving ground. Tetrachloroethane (TeCA) and trichloroethene (TCE) were not degraded in the ground water. However, when the water was discharged through an organic-rich wetland, the natural microbial populations converted TeCA and TCE to less chlorinated compounds and finally to nonhazardous end products. Thus, for much of the wetland, natural attenuation was a sufficient treatment strategy. However, in some areas, contaminated water was entering the tidal waters of West Branch Canal Creek, and further treatment was necessary. Areas of the wetland where the contaminants were breaking through were identified and a bioaugmentation treatment was applied in a “biomat” on the sediment surface. A microbial consortium was developed from sediment collected from contaminated wetland sediments where natural attenuation was effective. Application of this microbial consortium in the biomat successfully removed chlorinated ethenes and ethanes and chlorinated methanes (such as carbon tetrachloride).

This consortium of bacteria and methanogens has been developed in our U.S. Geological Survey lab at Reston, VA. This consortium, in development since 2002, was started using Aberdeen sediment, and enriched and grown in a medium with chlorinated compounds as terminal electron acceptors. The culture was scaled up by Geosyntec in Guelph, Canada for use in a field test at Aberdeen Proving Ground. The microbial consortium was deployed in a permeable layer of soil materials that was constructed over a "hot spot" of chlorinated compound discharge in the wetland. The field test was monitored for its effectiveness in removing chlorinated compounds and prevented the release of these toxic compounds in the waters of West Branch Canal Creek, a tidal wetland. WBC-2, was analyzed using molecular techniques such as cloning and sequencing. The culture is methanogenic and includes fermentative and acetogenic bacteria in addition to recognized dechlorinating bacteria such as Dehelobacter restrictus, Geobacter lovleyi, Dehalococcoides sp., Syntrophus, Sytrophobacter and Synergistetes. In addition to dechlorinating aliphatic hydrocarbons, it can also degrade other recalcitrant organics.

For more information view Microbiology and Molecular Ecology at Aberdeen, MD and the following publications:

Aberdeen Publication - WRIR-02-4157
Anaerobic Degradation of 1,1,2,2-Tetrachloroethane and Association with Microbial Communities in a Freshwater Tidal Wetland, Aberdeen Proving Ground, Maryland: Laboratory Experiments and Comparisons to Field Data.
By Michelle M. Lorah, Mary A. Voytek, Julie D. Kirshtein, and Elizabeth J. (Phillips) Jones

Jones, E.J.P., Voytek, M.A., Lorah, M.M., and Kirshtein, J.D., 2006, Characterization of a microbial consortium capable of rapid and simultaneous dechlorination of 1,1,2,2-tetrachloroethane and chlorinated ethane and ethene intermediates: Bioremediation Journal, v. 10, p. 153-168.

Also contact Mary Voytek, Voytek Microbiology.

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