Transformation of trichloroethylene by sulfate-reducing cultures enriched from a contaminated subsurface soil

Trichloroethylene (TCE) was reductively dechlorinated to cis-1,2-dichloroethylene (cDCE) by sulfate-reducing cultures enriched from a contaminated subsurface soil. The highest observed transformation rate of TCE was 213 mumol l-1 per day at 35 degrees C. The predominant biotransformation product was cDCE. However, further dechlorination of cDCE was not observed in most of the cultures. Methane production was insignificant and active sulfate reduction was achieved by maintaining excess sulfate. A comparison of sodium sulfide and sodium dithionite for their effect on the transformation of TCE revealed that the latter is a better reducing agent. The extent of TCE transformation in 25 days was ca. 20% higher in the dithionite-amended cultures. A decrease in the rate and extent of TCE transformation was observed with an increase in the concentration of bromoethanesulfonate up to 50 mM.