Removal of COD from industrial biodiesel wastewater using an integrated process: electrochemical-oxidation with IrO2-Ta2O5/Ti anodes and Chitosan powder as an adsorbent

Abstract

The production of biodiesel is an energy and water-intensive process that produces wastewater with high concentrations of COD, BOD, and FOG. Conventional treatment processes are not capable of treating contaminants and pollutants in biodiesel wastewater to satisfactory concentrations, and hence, advanced treatment processes are necessary. Untreated discharge of biodiesel wastewater results in additional costs during the production of biodiesel when penalties and fines are applied. In this research, a lab-scale integrated treatment process was used to investigate the successful abatement of contaminants, COD, BOD and FOG, present in industrial biodiesel wastewater. The integrated treatment process consisted of three consecutive steps: acidification, electrochemical oxidation, and adsorption. Acidification as a pre-treatment occurred at a pH of 2. Electrochemical oxidation using IrO2-Ta2O5/Ti anodes at a current density of 1 mA/cm2 and NaCl concentration of 0.08 M was followed by three consecutive adsorption stages using Chitosan powder at a concentration of 4.5 g/L. The experimental results show that the integrated treatment process could reduce COD, BOD and FOG levels by 94%, 86% and 95%, respectively. The treated effluent complies with local industrial effluent discharge standards, which could be disposed of safely without further treatment.