Surfactant wastewater is usually difficult to treat due to its toxicity and poor biodegradability. A separate physico-chemical or biochemical treatment method achieves a satisfactory effect with difficulty. In this study, treatment of the wastewater collected from a daily chemical plant by the combination processes of Fe/C internal electrolysis and biological contact oxidation was investigated. For the internal electrolysis process, the optimal conditions were: pH = 4–5, Fe/C = (10–15):1, air–water ratio = (10–20):1 and hydraulic retention time (HRT) = 2 h. For the biological contact oxidation process, the optimal conditions were: HRT = 12 h, DO = 4.0–5.0 mg/L. Treated by the above combined processes, the effluent could meet the I-grade criteria specified in Integrated Wastewater Discharge Standard of China (GB 8978-1996). The results provide valuable information for full-scale linear alkylbenzene sulfonate wastewater treatment.
Keywords: biological contact oxidation, internal electrolysis, LAS wastewater