Stimulation of Aerobic Degradation of Chlorinated Ethenes in Soil by Microbial Inoculation

摘要

Recently, we encountered a situation where shallow contamination sandy soils combined to create aerobic conditions, which prevented the degradation of chlorinated ethenes by reductive dechlorination. Biodegradation of chloroethenes under aerobic conditions can be difficult to achieve, however, it can be enhanced if microorganisms capable of cometabolic degradation are introduced into the soil. In this study trichloroethylene (TCE) removal in the soil was enhanced by the injection of a CL-Out inoculum and nutrients and was compared to chlorinated ethene removal in soil that had received nutrients only and soil that had received activated sludge and nutrients. TCE removal was measured after 1 week, 7 weeks and 11 weeks. After 1 week, no significant TCE removal had occurred in any of the test microcosms. After 7 weeks, a slight decrease in TCE levels accompanied by an increase in cis-l,2-dichloroethylene (cis-1,2-DCE) was seen in the microcosms that had received CL-Out. After 11 weeks, a marked decrease in TCE levels was observed in the microcosms that had received CL-Out. No significant TCE decrease was observed in any of the other microcosms. These data suggest that organisms capable of aerobic TCE degradation were not present at the Site however the addition of an inoculum containing such organisms could allow aerobic degradation at the Site to occur.