Bioremediation of trichloroethylene and cis-1,2-dichloroethylene-contaminated groundwater by methane-utilizing bacteria.

Experimental studies on the bioremediation of groundwater contaminated with low concentration trichloroethylene (TCE) and cis1,2-dichloroethylene (DCE) were performed with two sets of bioreactors. Reactors No. 1 and No. 2 were operated without and with methane supplement, respectively. No inoculum was used. The concentrations of TCE and DCE in the effluent and the off gas from reactor No. 2 were much lower than those from reactor No. 1. When air and an H2O2 solution were supplied to reactor No. 2, concentrations of TCE and DCE in the effluent and the off gas were lower than the lowest detectable limit. The population of methane-utilizing bacteria in reactor No. 2 was 1,000 times higher than that in groundwater or in the effluent from reactor No. 1. These methane-utilizing bacteria were apparently attributable to the treatment of TCE.