AEROBIC COMETABOLIC TRANSFORMATION OF TRICHLOROETHYLENE AND cis-DICHLOROETHYLENE IN PROPANE FED AQUIFER MICROCOSMS

摘要

A 15-microcosm matrix was created to determine the potential for using propane-utilizing microorganisms to aerobically cometabolize chlorinated aliphatic hydrocarbons (CAH) at McClellan Air Force Base, California. Microcosms were constructed using aquifer materials and groundwater that were aseptically obtained from the treatment location where cometabolic air sparging (CAS) tests were conducted using propane as the primary substrate. Trichloroethylene (TCE) and 1,2-cis-dichloroethylene (c-DCE) were tested at concentrations near those found at the field site. Unlike the field demonstration, the lag time to onset of propane utilization took only 9-12 days of incubation. Upon stimulation with propane both CAHs were readily transformed. Nitrogen limitations similar to those observed in the field demonstration were observed in microcosms prepared with site groundwater and no nitrogen amendments. Propane utilization rates decreased and TCE transformation ceased when nitrate became limiting in the microcosms. Both nitrate and ammonia were found to restore propane oxidation rates and to cause resumption of CAH transformation. Microcosm transformation yields of 0.035 μg c-DCE/μg propane and 0.053 μg TCE/μg propane were obtained when nitrogen was not a limiting factor.