Cometabolic microbial degradation of trichloroethylene in the presence of toluene.

Trichloroethylene (TCE), a common groundwater pollutant, was cometabolized by microorganisms in the presence of toluene as a growth substrate. The effect of concentrations of toluene and TCE and temperature on biodegradation was discussed. Acclimated microorganisms degraded TCE after a lag period of 5 to 22 h depending on toluene concentrations. Approximately 60%, 90% and 64% of TCE were degraded at toluene to TCE concentration ratios of 23:1, 115:1 and 230:1, respectively. At a TCE concentration of 1.46 microg/ml, 80% of TCE and 98.4% of toluene were removed. But less degradation of TCE and toluene was observed when TCE concentration was above 48.8 microg/ml. The lag time of TCE decreased and the TCE biodegradation rates increased with the increase of temperature.