Chromium removal from tannery wastewater by electrocoagulation: Optimization and sludge characterization

The treatment of tannery effluent is of great interest as it contains a complexmixture ofpollutants, primarily chromium. The disposal of this wastewater can have adverse effects on the environment and aquatic life, which is an emerging problemfor the environment. In this work, electrocoagulation is used to remove chromium from real tannery wastewater, focusing on performance optimization and sludge characterization. Electrocoagulation experiments were conducted using an electrochemical cell with iron electrodes immersed in a specific volume of tannery wastewater. Operating parameters, such as the initial chromium concentration, pH and current density as well as power consumption were evaluated to determine optimum chromium removal. The optimizationwas performed using Response Surface Methodology combined with central composite design. Analysis of variance (ANOVA) was used to determine the response, residual, probability, 3D surface and contour plots. The maximum chromium removal was 100% at the optimum values of 13 mA/cm2, 7 and 750 ppm for current density, pH and concentration, respectively.This research received no external funding. The authors are grateful to the staffof the Gas Processing Center (GPC) for their help with the experimental work, especially Ahmed Soliman and Dan Cortes. They would also like to thank the Environmental Research Centre, the Chemical Engineering Department, and the Central Laboratory Unit at Qatar University for their support.Scopu