BIODEGRADATION OF CHLORINATED ETHENES BY NATURALLY OCCURRING MICROBES IN WETLAND SOILS BOTH IN BATCH AND COLUMN STUDY

The biotransformation of several chlorinated ethenes or CEs (1,1-divchloroethene; trans- 1,2-dichloroethene, cis-1,2-dichloroethene or DCE and vinyl chloride or VC) under various electron-accepting conditions is investigated at bench scale by using enrichment culture obtained from a shallow soil core collected from a local wetland. The anaerobic microbial enrichment cultures were capable of degrading CEs using nitrate and sulfate as electron acceptors. The results indicated that the DCEs and VC were degraded under nitrate reducing conditions both in batch and column experiments. The microcosms were frequently amended with nutrient solutions and 200mg/L yeast extract or sometimes with acetate (carbon source). The rate constant of degradation for the above CEs appears to vary among the condition studied, as the removal rate of a particular CE was slower in batch experiment compare to column experiment. Further, the degradation of 1,1-DCE; trans-DCE; cis-DCE and VC were also observed in aerobic condition in slurry microcosms prepared with wetland soil, and without addition of a carbon substrate, where DCEs or VC may have served as sole carbon sources and oxygen as a terminal electron acceptor. The biodegradation of various CEs under sulfate reducing condition is still under investigation.