Anaerobic degradation of pentachlorophenol (PCP) in biological expanded-bed reactor

Abstract

In this study, anaerobic degradation of PCP was discussed in an expanded-bed GAC anaerobic reactor which was applied to treatment of wastewater containing high concentration of PCP-Na as well as acetate. Total-COD concentration in effluent was kept less than 100 mg/L except for the start-up duration and PCP-Na concentration was kept less than 0.50 mg/L under the experimental conditions (HRT of 5 days, influent PCP-Na concentration of 100 and 400 mg/L, and influent Total-COD concentration of 480 and 1600 mg/L). It was indicated by methane production rate and material balance of PCP-Na that about 60% of PCP-Na loaded into the reactor was transformed to methane and CO₂ for 375 days. GC/MS analysis of extracts of the GAC medium and effluent indicated that reductive dechlorination of PCP occurred and dechlorinated phenols were adsorbed on the GAC in the reactor. Microorganisms collected from the reactor degraded PCP-Na and 2-CP anaerobically and addition of acetate in culture accelerated anaerobic degradation of PCP-Na in batch experiments.