Treatment of Coking Wastewater by an Anaerobic/Anoxic/Zeolite Biofilter-MBR Process

A lab-scale anaerobic/anoxic/zeolite biofilter - membrane bioreactor (A₁/A₂/ZB-MBR) was developed and its performance in coking wastewater treatment was investigated. The operation parameters were optimized. The results indicated that the zeolite could regulate the concentration of ammonia effectively. The best performance was obtained at HRT 73 h, reflux ratio 2:1, DO 4-6 mg/L in ZB-MBR. Under the optimal influent conditions of COD_Cr (1 673±227) mg/L, NH₃-N (125.0±27.4) mg/L, TN (280.5±57.6) mg/L, the effluent COD_Cr, NH₃-N and TN were (145±27) mg/L, (5.6±4.1) mg/L, and (91.4±33.8) mg/L, respectively, and the performance remained stable over 280 d operation.