Enhanced biotransformation of trichloroethylene under mixed electron acceptor conditions

The biotransformation of trichloroethylene (TCE) under various electron acc eptor conditions was investigated by using enrichment cultures developed fr om the anaerobic digester sludge of Thibodaux sewage treatment plant. The r esults indicated that TCE was biotransformed under sulfate reducing, methan ogenic, nitrate reducing, iron reducing, and fermenting conditions. However , the rates of TCE removal varied among the conditions studied. The fastest removal of TCE (100% removal in 9 days) was observed under mixed electron acceptor conditions, followed in order by methanogenic, fermenting, iron re ducing, sulfate reducing, and nitrate reducing conditions. Under mixed elec tron acceptor conditions, the TCE was converted to ethene, which was furthe r metabolized. Under sulfate and nitrate reducing conditions, the major met abolites produced from TCE metabolism were cis and trans dichloroethylene ( DCE). Under methanogenic, iron reducing, and fermenting conditions, cis and trans DCE and ethene were produced from TCE metabolism. This study showed evidence for TCE metabolism in a mixed microbial population system similar to any contaminated field sites, where heterogeneous microbial population e xists.