Evaluation of Electro-chemical Methods in Wastewater Treatment of Wheat Starch Industry

Abstract

Wastewater from wheat starch industries is the one with high chemical oxygen demand (COD) level that has adverse effects on the environment and thus special attention to its treatment for the discharge limits satisfaction is crucial. Biological treatment methods have challenges such as requiring extensive space and process time, high sludge production, and efficient management and operation demands. To overcome these challenges, electrochemical methods such as electrocoagulation (EC) and electro-Fenton (EF) can be efficient approaches due to their higher process speeds, minimal facility requirements, and easy operation which make them economically viable. In this study, electrochemical processes, including EC and EF methods were applied for wastewater treatment of a wheat starch industry. After preliminary experiments to identify the effective factors and ranges, the response surface method (RSM) was applied to design the experiments. In RSM seven factors were considered including initial COD, pH, electrode distances, process time, temperature, current intensity, and hydrogen peroxide concentration along with the COD removal efficiency as the response. Statistical analysis showed that hydrogen peroxide concentration and initial COD had the most significant impact, while pH had the least effect on COD removal in the electrochemical process. The optimum results showed that for synthetic wastewater with an initial COD range of 2000–4000 mg/L a COD removal of 75–85% for EC and 89–93% removal for EF were obtained. The results were validated for raw natural wastewater with 88% removal for EC and 92% for EF. In conclusion, while the removal efficiency of the EF process was superior to EC, the former incurs higher costs due to the use of hydrogen peroxide.