Treatment of pretreated coke wastewater by electrocoagulation and electrochemical peroxidation processes

Abstract

In this study, treatment of pretreated real coke wastewater by Electrocoagulation process (EC) and Electrochemical Peroxidation process (ECP) using direct pulse current was investigated. Air stripping process of ammonia was used as a physicochemical process for the pretreatment of wastewater. In the present study, ECP process has been offered to remove chemical oxygen demand (COD), total organic carbon (TOC), phenol, cyanide (CN-) and thiocyanate (SCN-) from coke wastewater. The efficiency of the process and settling characteristic of waste sludge were investigated through changing some operating parameters such as initial pH, initial H2O2 concentration and current density. Direct pulse current (DPC) was used to prevent the passivity or polarization of electrodes and to increase removal efficiency. Under the optimum operation conditions at the EC and ECP process (pH 3, current density 200 A/m(2), initial H2O2 10 g/L (for ECP), operation time 20 min.), the removal efficiencies of COD, TOC, phenol, CN- and SCN- were observed to be 26%, 20%, 9%, 9.2% and 8.2% (for EC) and to be 92.0%, 90.0%, 97.6%, 90.0% and 93.6% (for ECP), respectively. Operating costs for the EC and ECP process were calculated as 1.46 (sic)/m(3) and 5.64 (sic)/m(3). These results asserted that ECP process was more effective than EC process for removal efficiencies of pollutions. But, the ECP process was more expensive than EC process. (C) 2015 Elsevier B.V. All rights reserved.