Studies on the Removal of Nitrogen and COD from Municipal Wastewater by Electrocoagulation

Abstract

Due to enormous human activities such as industrialization, and the use of excessive fertilizers, the discharge of nutrient-rich wastewater into recipient water bodies is leading to eutrophication. Eutrophication causes a decrease in dissolved oxygen (DO) levels in water bodies, leading to a toxic environment for aquatic life. In this study, an electrocoagulation (EC) cell is used to reduce nitrogen and COD in municipal wastewater employing aluminum and iron electrodes. The effect of the main operational parameters pH, electrolysis time, current density, inter-electrode distance, temperature, concentration, agitation speed, and electrode material are studied. Experimental analysis is carried out using ‘Response Surface Methodology’ (RSM) by designing experiments using ‘Design Expert’ software. Mathematical models are developed for COD and ammoniacal nitrogen, achieving high predictive proportions of variance with high R² values of 0.9781 and 0.9625 for COD and ammoniacal nitrogen respectively. Process optimization has yielded optimum conditions of pH 7, voltage 8 V, runtime 85 minutes, agitation speed 225 rpm, temperature 57°C, inter-electrode spacing 3 cm, and initial nitrogen concentration of 40 ppm. The application of electrocoagulation for the treatment of Ananthapuramu municipal wastewater with an initial concentration of nitrogen 23.6 ppm under optimal conditions allowed for the removal of 80.17% ammoniacal nitrogen and 84.96% COD. The results demonstrate the effectiveness of electrocoagulation in treating municipal wastewater, making it suitable for discharge into water bodies.