Degradation of 4-Chlorophenol in Denitrifying Fluidized-Bed Process

Chlorophenol degradation by dissimilatory nitrate reduction was studied in an anoxic fluidized-bed reactor. 4-Chlorophenol (4-CP) served as a carbon source for denitrification although both 4-CP and nitrate removals remained incomplete (23–82 and 9-60%, respectively) at 5 h hydraulic retention time. Under varying experimental conditions, 1.9-2.5 mg 4-CP was degraded and dechlorinated per 1 mg NO3-N reduced. This is higher than the theoretical 4-CP/NO3-N ratio of 1.8 and the difference is likely due to aerobic degradation in the presence of trace concentrations of oxygen. The mass balance based on inorganic chloride release and disappearance of the parent compound gave further evidence of chlorophenol degradation in the system.