Treatment of Carwash Greywater Through Electrocoagulation: Effect of Time of Treatment and Inter-electrode Distance

There is a growing concern over the availability of water resources worldwide, and so there is a pressing need to reclaim greywater across different industries. Carwash stations in particular waste large amounts of water and consequently produce greywater that is left untreated and un-reclaimed. In this study, carwash greywater was treated using electrocoagulation (EC) to test the effectiveness of the process. The greywater samples were collected from a local carwash station. The inter-electrode distances (2, 2.5, and 3 cm) and time of treatment (15, 30, and 45 min) were varied at a constant pH level of 7 and constant current density of 7.5 mA/cm2 using iron and aluminum electrodes as the cathode and anode, respectively. The efficiency of the EC process was determined through measuring the removal percentage of turbidity, chemical oxygen demand (COD), and total organic carbon (TOC). The results show that the optimum inter-electrode distance for turbidity removal is 2 cm with a mean removal efficiency value of over 90%. The COD removal efficiency ranged between 33 and 39% for all the tested parameters. The time of treatment had no clear effect on the removal of COD and TOC. The optimal inter-electrode distance and time of treatment for this study were 2 cm and 30 min at which the turbidity, COD, and TOC removal efficiencies were 93%, 37%, and 24%, respectively. The results of this study show the potential of the EC process in treating carwash water. Future studies should focus on investigating more variables for carwash treatment using EC to enhance the removal of pollutants and allow reuse of treated carwash wastewater. The operational cost at the optimal parameters is 0.12 USD m−3, making EC a cost-effective treatment option.