Pilot‐scale electrochemical oxidation combined with constructed wetland system for unconventional surface water treatment

Abstract

AbstractBACKGROUNDWenyu River is a typical unconventional surface water due to receiving effluent from wastewater treatment plants. Its water is of poor biodegradability and low carbon–nitrogen ratio, thus it is difficult to meet III Grade of Surface Water Quality Standard of China using conventional biological treatment technology for its remediation. In addition, total nitrogen is strictly required to be less than 15 mg L−1.RESULTSA novel pilot‐scale hybrid system, electrochemical oxidation and constructed wetland, has been developed for nitrogen and carbon removal from Wenyu River, focusing on NH4+‐N, TN, COD and BOD5 removal operation over 162 days with average effluent value of 0.44, 10.37, 18.3 and 4.0 mg L−1, respectively. Average value of BOD5/TN and BOD5/COD was enhanced from 0.65 to 0.97 and from 0.36 to 0.52, respectively, by electrochemical oxidation, NH4+‐N removal mainly contributed to indirect oxidation of chlorine ion in the unit. Meanwhile, based on data at a voltage of 6 V, the operating cost of this hybrid system was estimated to be 0.89 RMB m−3 with an energy consumption of 38.4 kWh kg−1COD in the pretreatment unit.CONCLUSIONIt is feasible to apply the hybrid system for unconventional surface water treatment and to achieve acceptable effluent quality and steady process performance. © 2014 Society of Chemical Industry