Aerobic metabolic trichloroethene biodegradation under field-relevant conditions

Abstract

Chloroethenes belong to the most widely distributed groundwater contaminants. Since 2014, it has been known that trichloroethene (TCE) can be degraded aerobically and metabolically as growth substrate by a mixed bacterial enrichment culture (named SF culture). In this study, the degradation capabilities under a range of field-relevant conditions were investigated in fixed-bed reactors as well as in batch experiments. Aerobic metabolic TCE degradation was stable over the long term, with degradation optima at 22 °C and pH 7. Degradation of up to 400 μM TCE was observed. The longest starvation period after which degradation of TCE was regained was 112 days. The possible co-contaminants perchloroethene, trans-1,2-dichloroethene, and cis-1,2-dichloroethene did not inhibit TCE degradation, even though they were not degraded themselves. The presence of equimolar amounts of 1,1-dichloroethene and vinyl chloride inhibited TCE degradation. Experiments with groundwater from different chloroethene-contaminated field sites proved the potential of the SF culture for bioaugmentation. Thus, aerobic metabolic TCE degradation should be considered as a promising method for the bioremediation of field sites with TCE as the main contaminant.

Keywords: Aerobic metabolic biodegradation; Bioaugmentation; Bioremediation; Field conditions; Trichloroethene.