Mechanistic Study and Multi-Response Optimization of the Electrochemical Treatment of Petroleum Refinery Wastewater

Petroleum refinery wastewater (PRW) is refractory in nature. Electrochemical (EC) treatment of PRW can remove toxic pollutants present in it. The present paper deals with the treatment of the PRW in a batch EC reactor using stainless steel electrodes. Parametric optimization is carried out using full factorial central composite design to maximize the removal of chemical oxygen demand (COD) and the total organic carbon (TOC). The mechanism of COD and TOC removal is elucidated by carrying out zeta potential measurement, UV-vis spectroscopy, and Fourier-transform infrared (FTIR) spectroscopy. Under optimized operating conditions of initial pH:6, current density = 182 A m(-2), electrode gap = 1.5 cm, and time = 145 min, the removal efficiency of COD and TOC is found to be 62 and 52%, respectively. The sludge generated during EC treatment is characterized by FTIR, elemental and thermo-gravimetric analysis.