Simultaneous removal of nitrate and pentachlorophenol from simulated groundwater using a biodenitrification reactor packed with corncob.

Both nitrate and pentachlorophenol (PCP) are familiar pollutants in aqueous environment. This research is focused on the simultaneous removal of nitrate and PCP from simulated contaminated groundwater using a laboratory-scale denitrification reactor packed with corncob as both carbon source and biofilm support. The reactor could be started up readily, and the removal efficiencies of nitrate and PCP reached up to approximately 98% and 40-45% when their initial concentrations were 50 mg N/L and 5 mg/L, respectively, after 15-day continuous operation at 10 h of hydraulic retention time (HRT) and 25 °C. Approximately 91% of PCP removal efficiency was achieved, with 2.47 mg/L of chloride ion release at 24 h of HRT. Eighty-two percent of chlorine in PCP removed was ionized. The productions of 3-chlorophenol and phenol and chloride ion release indicate that the reductive dechlorination reaction is a major degradation pathway of PCP under the experimental conditions.