Removal of Recalcitrant Carbon from an Industrial Wastewater Using Electrocoagulation

Abstract

Manufacturing industries synthesize new chemical products every day, which eventually find their way into domestic and industrial wastewaters. As a result, wastewater is becoming increasingly more complex in nature. The emerging pollutants escape the treatment systems and appear in the receiving water bodies. Wastewater treatment plants in India still report effluent parameters in terms of biological oxygen demand (BOD) and chemical oxygen demand (COD) at the ppm level, whereas these emerging pollutants, many of whom are non-biodegradable, can be toxic and carcinogenic at the ppb level. Therefore, it is imperative to look for alternatives or upgrade the existing systems which safely remove these harmful compounds from wastewater. In this research, efficiency of electrocoagulation process was assessed in a laboratory-scale setup in removing recalcitrant carbon from a real wastewater. The wastewater was collected from an effluent treatment plant that receives domestic wastewater and industrial effluents from chemical, bulk drugs and allied industries, for treatment. In this study, the wastewater sample was analyzed for total dissolved solids (TDS) and total organic carbon (TOC), and then treated biologically in a respirometer using aerobic microorganisms. After the oxygen uptake curve plateaued, indicating a cessation of biological process, the sample was analyzed for TDS and TOC and put in a lab-scale electrocoagulation setup. Iron and Aluminium electrodes were used in the study and efficiency of the system in removing the recalcitrant/residual carbon and TDS was studied with respect to the reaction time. The results showed that electrocoagulation can be a potential post-biological treatment system for removal of recalcitrant carbon from wastewaters.