Complete Reductive Dechlorination of Trichloroethene by a Groundwater Microbial Consortium^a

Abstract

Bioremediation promises to be an important technique in the removal of trichloroethene (TCE) and tetrachloroethene (PCE) from contaminated waste sites and contaminated groundwater systems. However, the use of aerobic degradation to degrade these compounds is not always possible. Thus, anaerobic degradation is a promising alternative that may be used to remediate these sites. Recently, literature reports indicate complete anaerobic dechlorination of TCE and PCE by microorganisms enriched from wastewater treatment plants. We report here the complete dechlorination of TCE to ethene in anaerobic microcosms by microorganisms enriched from a TCE contaminated groundwater aquifer using glucose as an electron donor. Initial TCE degradation activity occurred after 10 days of incubation and TCE was no longer detected after 20 days of incubation. During the incubation period, the reductive dechlorination products associated with TCE degradation were detected. Ultimately, all of the TCE was converted to ethene. The glucose culture was further enriched and demonstrated increased rates of TCE conversion to ethene. Our results show that organisms isolated from a contaminated groundwater site are capable of completely degrading TCE to ethene at appreciable rates, and indicate the potential of using in situ anaerobic bioremediation to clean up TCE contaminated sites.