Multi-Response Optimization of Electrocoagulation Parameters for the Removal of COD, Phenol, and Colour from Petrochemical Wastewater

Managing oily wastewater remains a significant challenge due to its complex composition, which usually includes high levels of chemical oxygen demand (COD), phenolic substances, and chromophoric compounds. This study examines the performance of electrocoagulation (EC) using aluminium electrodes to simultaneously remove COD, phenol, and colour from wastewater emanating from an oil refinery. A series of controlled batch experiments was carried out to evaluate how operational variables, such as current density, pH, and electrolysis time, influence treatment efficiency. Under optimized conditions (i.e., pH 6, a current density of 11 mA/cm2, and an electrolysis time of 57 minutes), the system achieved removal efficiencies of 92.67% for COD, 92.94% for phenol, and 97.86% for colour. These results highlight the effectiveness of EC as a standalone treatment method. The findings confirm the suitability of aluminium-based EC for treating oily industrial wastewater, providing significant pollutant removal with minimal use of chemical reagents. The study supports further development of EC as a scalable, resource-efficient, and environmentally friendly approach to managing industrial effluents.