Electrocoagulation for COD, turbidity, ammonia and phosphate removal from municipal wastewater

The study illustrates, viability of using electrocoagulation as a process for COD, turbidity, ammonia and phosphate removal from real municipal wastewater (MWW). Experiments were performed in batch mode at laboratory scale with stainless steel as cathode and aluminium as anode. Constant voltage of 12 V was used throughout the experiments. Effects of inter- electrode distance and current were evaluated for removal of COD, turbidity, ammonia and phosphate from MWW. Effect of interelectrode distance was tested for this, the spacing between electrodes was fixed at 3 cm, 5 cm and 7 cm. The highest COD removal efficiency of 89% was observed at 3 cm inter-electrode distance followed by 84% and 82% at 5 cm and 7 cm, respectively. Ammonia reduction was 55%, 38% and 32% at 3 cm, 5 cm and 7 cm inter- electrode distance, respectively. Phosphate removal was 99% at 3 cm and 98% both at 5 cm and 7 cm. Turbidity removal also followed the same trend, at 3 cm maximum removal of 95.5% was recorded and at 5 cm and 7 cm 94% and 93% removal occurred, respectively. Another operating parameter studied was the influence of current by applying 0.5 A, 1 A and 2 A. Maximum COD, turbidity, ammonia and phosphate removal occurred at 2 A. COD removal of 76%, turbidity removal of 94%, ammonia reduction of 72% and phosphate reduction of 98% was recorded at 2 A which was maximum for all these parameters. From the current study, it can be highlighted that electrocoagulation is suitable for COD, ammonia, phosphate and turbidity removal. Operating cost calculated was 0.12, 0.24 and 0.48 USD/m(3) for 0.5 A, 1 A and 2 A, respectively. Further studies on continuous mode operation, characteristics of sludge formed, and additional treatment needs to be carried out.