Biodegradation of trichloroethylene by bacteria indigenous to a contaminated site

Abstract

Bacteria indigenous to a trichloroethylene (ICE) contaminated site were used in a batch-microcosm experiment to determine their ability to grow in the presence of and degrade ICE. At two different initial concentrations of ICE, bacterial populations were able to increase their number by two orders of magnitude. Under the aerobic, oligotrophic conditions of the microcosms, the average ICE disappearance in live microcosms for all samples was 47 percent and 33 percent when the initial concentration was 559 ppb and 6.7 ppm, respectively. No TCE disappearance was observed in blank or killed microcosms. It is believed that bacteria degraded ICE to levels as low as 1-2 percent of the initial concentration. Lag times of 14 and 18 days, were observed for the low- and high-concentration microcosms, respectively. Bacterial population shifts were noted throughout the experiment. None of the volatile chlorinated compounds expected as products of biodegradation were found.