|Microbial Consortium that Dechlorinates 1,1,2,2 Tetrachloroethane and all its Daughter Products
| 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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