Anaerobic Removal of Pentachlorophenol in Presence of Zinc

Abstract

The objective of this research was to determine the toxic effects and degradation of pentachlorophenol (PCP) in the presence of zinc in anaerobic propionate systems. Anaerobic toxicity assays (ATA), batch kinetic studies, and biodegradation studies were performed using serum bottles. PCP inhibition was modeled using both uncompetitive and noncompetitive inhibition kinetic models with an inhibition coefficient, K{sub I}, of 0.06 mg/L. Zinc toxicity showed that the competitive inhibition model was the best-fit with a K{sub I} of 1.1 mg/L. A combined competitive-uncompetitive inhibition model was the best-fit model in the presence of both PCP and zinc for propionate degradation. In the biodegradation studies, PCP removals were 72, 64, and 54% with spiked PCP concentrations of 2, 3, and 5 mg/L, respectively. In the presence of zinc, the removal of 2 mg/L and 3 mg/L of PCP decreased to 60% and 53%, respectively. The intermediates of PCP degradation were 2,4,6-trichlorophenol, 2,4-dichlorophenol, 4-chlorophenol, 2,3,5-trichlorophenol, 3,5-dichlorophenol, and 3-chlorophenol; lower concentrations of these intermediates were observed in the presence of zinc.