The occurrence and fate of phenolic compounds in a coking wastewater treatment plant

The occurrence of 14 phenolic compounds (PCs) was assessed in the raw, treated wastewater, dewatered sludge and gas samples from a coking wastewater treatment plant (WWTP) in China. It was found that 3-cresol was the dominant compound in the raw coking wastewater with a concentration of 183 mg L-1, and that chlorophenols and nitrophenols were in the level of mu g L-1. Phenol was the dominant compound in the gas samples, while 2,4,6-trichlorophenol predominated in the dewatered sludge sample. The anaerobic and aerobic tanks played key roles in the elimination of chlorophenols and phenols, respectively. Analysis of daily mass flows of PCs in WWTP showed that 89-98% of phenols and 83-89% of nitrophenols were biodegraded, and that 44-69% of chlorophenols were adsorbed to sludge, indicating that the fate of PCs was highly influenced by their biodegradability and physical-chemical property.