SEQUENTIAL ANAEROBIC-AEROBIC BIODEGRADATION OF PCBS IN SOIL SLURRY MICROCOSMS

Many industrial locations have identified the need for treatment of po lychlorinated biphenyl (PCB) wastes and remediation of PCB-contaminate d sites. Biodegradation of PCBs is a potentially effective technology for treatment of PCB-contaminated soils and sludges; however, a practi cable remediation technology has not yet been demonstrated. In laborat ory experiments, soil slurry microcosms inoculated with microorganisms extracted from PCB-contaminated Hudson River sediments have been used for anaerobic dechlorination of weathered Aroclor 1248 in contaminate d soil with a low organic carbon content. Anaerobic incubation was the n followed by exposure to air, addition of biphenyl, and inoculation w ith Pseudomonas sp. LB400, an aerobic PCB degrader. The sequential ana erobic-aerobic treatment constituted an improvement compared to anaero bic or aerobic treatment alone by reducing the total amount of PCBs re maining and decreasing the tendency for end products to accumulate in humans. A 70% reduction of PCBs was observed during sequential treatme nt with products containing fewer chlorines and having a shorter half- life in humans than the original PCBs. The aerobic treatment alone was also quite effective as a stand-alone treatment reducing the PCBs by 67%. The results represent a case in which anaerobic river sediment or ganisms have been successfully transferred to a matrix free of river o r lake sediments.