The Effect of Tetrachloroethene on Biological Determination of Vinyl Chloride: Potential Implication for Natural Bioattenuation

Although there is much interest in natural bioattenuation for remediation of chlorinated organic compounds at hazardous waste sites and industrial facilities, field data often show incomplete dechlorination that generates compounds of equal or greater toxicity than the starting compounds. The potential for sustaining vinyl chloride (VC) dechlorination using a methanogenic culture with perchloroethene (PCE)-dechlorinating capacity was studied. Ethene (ETH) production rates by a VC-fed culture were compared with those of a PCE-fed culture. Both cultures had identical physiochemical conditions, nutrients, and use of methanol as an electron acceptor. PCE-fed cultures sustained an ETH production rate of about 0.1 mu mol/d, while ETH production from VC-fed cultures declined to about 0.02 mu mol/d over 115 d. PCE addition to the VC-fed culture improved ETH production. Differential retardation of higher chlorinated ethenes may result in a contaminant plume with VC at the leading edge and declining VC dechlorination under anaerobic conditions.