Reductive dechlorination of chlorinated ethene DNAPLs by a culture enriched from contaminated groundwater

A microbial culture enriched from a trichloroethene-contaminated groundwate r aquifer reductively dechlorinated trichloroethene (TCE) and tetrachloroet hene (PCE) to ethene. Initial PCE dechlorination rate studies indicated a f irst-order dependence with respect to substrate at low PCE concentrations, and a zero-order dependence at high concentrations. Studies of TCE and viny l chloride (VC) dechlorination indicated a first-order dependence at all su bstrate concentrations. VC had little or no effect on the initial rate of T CE dechlorination. With subsaturating concentrations of chlorinated ethenes , nearly stoichiometric amounts of the toxic intermediate vinyl chloride ac cumulated prior to its dechlorination to ethene. In contrast, under saturat ing conditions, in which a dense, nonaqueous-phase liquid existed in equili brium with the aqueous phase, the chlorinated ethene was dechlorinated to e thene, at a rapid rate, with the accumulation of relatively small amounts o f chlorinated intermediates, (C) 1999 John Wiley & Sons, Inc. Biotechnol Bi oeng 62: 160-165, 1999.