Further treatment of coking wastewater treated in A2O-MBR by the nanofiltration-powder activated carbon hybrid system

Abstract

In this study, further treatment of coking wastewater treated in anoxic-oxic-membrane bioreactor (A2O-MBR) was investigated to meet the standards of the ministry by means of nanofiltration (NF) (with two different membranes and different pressures), microfiltration -powder activated carbon (MF-PAC) hybrid system and NF-PAC (with two different membranes and five different PAC concentrations) hybrid system. In addition to the parameters determined by the ministry, other parameters such as ammonium, thiocyanate (SCN−), hydrogen cyanide (HCN), dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), color were also examined to evaluate the flux performance and treatment efficiency of the hybrid processes. According to the results, chemical oxygen demand (COD) in the NF process, COD and total cyanide (T-CN) in the MF-PAC process could not meet the discharge standards. As for the NF-PAC hybrid system, XN45 membrane met the discharge standards in all parameters (COD = 96±1.88 mg/L, T-CN =<0,02 mg/L, phenol =<0.05 mg/L), with a recovery rate of 78% at 0.5 g/L PAC concentration. HIGHLIGHTS The effluent coking wastewater of the A2O-MBR system was treated by a membrane process.; NF, MF-PAC, and NF-PAC hybrid systems were used.; The flux performances of hybrid systems were investigated.; The removal efficiencies of pollutants, such as ammonium and HCN, were determined.; The hybrid system of XN45 with 0.5 g/L PAC achieved standards for all discharge parameters.;

Keywords

• coking wastewater
• further treatment
• microfiltration
• nf-pac hybrid system
• nanofiltration
• powder activated carbon