Study On Anaerobic Biodegradation Of PCE And Other Chlorinated Ethenes Under Different Conditions

Chlorinated compounds as an industrial and agricultural production commonly used organic solvents,due to many reasons that has entered the environment,endangering human health and ecological security.The biodegradation of chlorinated compounds has important theoretical value and application prospect because of its economic and harmless advantages.In this study,the degradation performance of Perchloroethylene(PCE)and low chlorinated compounds and the biodegradability of single strains were studied systematically.The effects of mixed bacteria on the biodegradability of chlorinated ethenes under different conditions were studied.The dominant hybrid bacteria,which was suitable for degradation of PCE,has been acclima-tized from soil contaminated by chlorinated aliphatic hydrocarbon,and applied on a series of batch experiments to investigate the anoxic PCE biodegradation under different condition.Analyzed the degradation and the kinetics of PCE in different substrates,and studied the effects of various anaerobic environmental factors.The results show that the mixed bacteria domestication can well adapt to different cometabolic substrates,the removal rate of PCE is higher,and the degradation of PCE in the water environment was consistent with the first order reaction kinetics.The optimum conditions were as follows: the inoculation amount was 20%(V/V),pH of 7.0 and the temperature was 25 ?.Under the optimum conditions for 14 days,the degradation rate of PCE reached 96.1%,and detected the production of TCE,cis-DCE and VC at the same time.The dominant hybrid bacteria,which was suitable for degradation of chlorinated ethenes,had been acclimatized from soil contaminated by chlorinated compounds and applied on a series of batch experiments.The results showed that the mixed bacteria domestication were always active and the degradation of chlorinated ethanes were all consistent with the first order reaction kinetics whatever one or more compounds existed.The removal of TCE,cis-DCE or VC also reached 96.8%,97.2%,95.3% respectively when only existed one chlorinated ethane.Coexisting contaminants had little effect on the deg-radation of TCE but obvious effect on cis-DCE which degradation rate was 23.3% lower than that existed sin-gly.The content of VC decreased evidently in each experiment.In the study,we got three strains of aerobic degrading bacteria and two strains of aerobic degrading bacteria from mixed bacteria cultured.They were named PA-1,PB-2,PH-3 and TA-1,TB-2 respectively.PA-1 had the best degradation ability to PCE,and was identified as Ralstonia sp..TA-1 and TB-2 had good degradation effect on lowchlorinated ethenes.Pseudomonas sp.and Escherichia sp..