Removal Of Trichloroethane And Its Toxical Effects On Bacterial Community In Anaerobic Sequencing Batch Reactors

1,1,1-Trichloroethane (TCA) as a cleaning solvent in manufacturing plants is widespread soil and groundwater contaminants due to extensive use and inappropriate disposal practices. environment. One approach for the cleanup of TCA-contaminated water is anaerobic bioremediation relies on stepwise reductive declorenation. In this study, anaerobic sequencing batch reactor (ASBR) was constructed to remove TCA contamination. The change of enzyme activity and bacterial communities was chosed to evaluate the toxic effects and metabolism of TCA in the ASBR. The result showed that the removal efficence of TCA was more than 80% under sulfate-reducing and nitrate-reducing conditions, approximate 70-80% under methanogenic and TCA and benzene co-metabolism conditions were lower than 70% under TCA and toluene co-metabolism condition after 21 days exposure. TCA had little effect on bacterial enzyme activities in methanogenic and nitrate-reducing conditions. The activity of lactate dehydrogenase and phosphatase decreased as the concentration of TCA increased. The microbial community significantly changed through 21 days of exposure to TCA. The TCA-biodegrading bacteria became the dominant functional bacterial populations, while other bacteria decreased under all conditions. Clostridium sp. DhR-2/LM-G01, Bacterial clone DCE25 and DPHB06 were enriched in the methanogenic ASBR systems which could effectively degrade TCA under anaerobic conditions. Based on the analysis of biodegration, enzyme activities and microbial community structure, the methanogenic ASBR system was most suitable to tolerate and metabolize TCA, which was potentially employed to develop the TCA bioremediation technology.