Optimization of EC parameters using Fe and Al electrodes for hydrogen production and wastewater treatment

Abstract

Electrocoagulation (EC) is an operative strategy to treat domestic wastewater in which coagulants are produced by in-situ electrolytic oxidation at the sacrificial anode. In this present study, EC was utilized in batch mode using iron (Fe), aluminium (Al) metal plates as electrodes in various combinations and optimized to achieve appreciable removal efficiencies. A laboratory-scale EC setup of capacity 5 litres was fabricated for treatment of waste-water which was sampled out from the sewage treatment plant of Indian Institute of Technology (IIT), Mandi. The influence of electrode material, pH, and current density is further explored for removal performance of turbidity, suspended solids, dissolved solids and organic matter. The optimum pH range for the removal of pollutants from the domestic wastewater was found to be in the range of 5-7, allowing the water treatment without the pH adjustment by any additional chemical. The process resulted into a removal efficiency of 91.8 % of COD, 94.3 % in the case of BOD and 96.5 % in the case of turbidity after treatment of 30 minutes with the combination of Al (at cathode) and Fe (at anode) with mono-polar electrode connection in parallel. The optimum current density of 1.25 mA cm−2 allows the complete treatment in 30 minutes with a very low energy consumption of 0.017 KWh. Along with wastewater treatment, we tried to capture hydrogen produced as a by-product during the EC process and the yield of hydrogen release is found to be 0.107 which plays a crucial role to reduce the overall cost of EC treatment. The importance of the operating parameters for an efficient EC process as well as the combination of the electrodes along with hydrogen capture technology is addressed.