A comparison between iron and mild steel electrodes for the treatment of highly loaded grey water using an electrocoagulation technique

In the last years, the electrocoagulation (EC) process has been widely used as a potential technique for grey water treatment. However, only a few studies have focused on treating highly loaded GW (HLGW) by EC. In this study, the EC technique was used to compare iron and mild steel electrodes for the treatment of HLGW under different current densities (CDs) (5, 10, 15, and 20 mA/cm2) during 10 min of EC time. The performance criteria included chemical oxygen demand (COD) and turbidity removal efficiencies, current efficiency, energy consumption, and operational costs. It was found that EC using iron or mild steel can be effective electrodes for removing high levels of COD and turbidity from HLGW. At optimum conditions, the study demonstrated that at a CD of 5 mA/cm2, mild steel-based electrodes reduced COD by 86.5% while iron-based electrodes achieved 85.3% reduction at 10 mA/cm2. In conjunction with these removals, the turbidity removals were 92% and 94% achieved by steel and iron electrodes, respectively. The current efficiency of all the conducted experiments exceeded 90% but was generally higher for iron electrodes. At optimum conditions, analysis of operating costs in terms of energy consumptions and electrode materials requirements were 0.054 $/m3 and 0.097 $/m3 achieved by steel and iron electrodes, respectively. Thus, mild steel-based electrodes are considered superior to iron electrodes. Based on the obtained results, the study recommends that further investigations should give attention to the effect of metal alloy type or physical properties of electrodes as performance criteria and designing aspects when studying EC technology for HLGW treatment due to its notable effect on removal efficiency and operational costs.