Identification of dechlorinating bacteria in a New Jersey fractured rock aquifer

Bioremediation is one approach to remove or detoxify groundwater contaminants. Microcosms made up of groundwater and sediment fines from the bottom of a monitoring well were used to determine the potential for reductive dechlorination in a tetrachloroethylene (PCE)-contaminated fractured rock aquifer in Piscataway, NJ. Complete dechlorination to ethylene occurred in the original, electron donors + PCE and VC-amended microcosms. Methane production was observed in all electron donor-amended microcosms. The VC dechlorination rate increased with each addition of VC. Little changed in the rate of PCE to DCE dechlorination, but slower rates of DCE to ethylene (via VC) dechlorination were observed with each addition of PCE. Dechlorination occurred in transferred PCE- and VC-amended enrichments; however, much faster dechlorination was observed in PCE-amended enrichments while a lag time was observed in VC-amended enrichments. The aquifer was electron donor limited, but supported a vigorous dechlorinating population. The use of groundwater and fine sediments recovered from monitoring wells by our method might be an effective approach for assessing biotransformation potential and microbial communities in fractured rock aquifer systems. This is an abstract of a paper presented at the 228th ACS National Meeting (Philadelphia, PA 8/22-26/2004).