Removal of microplastics and attached heavy metals from secondary effluent of wastewater treatment plant using interpenetrating bipolar plate electrocoagulation

Abstract

In this study, the mixed pollutants of microplastics and heavy metals from secondary effluent of wastewater treatment plant (WWTP) were removed by interpenetrating bipolar plate electrocoagulation (IBPE) reactor. Heavy metals and microplastics in the wastewater were simultaneously removed during the experimental process with high removal efficiency. The influences of current density, initial pH and reaction time on the removal rate were analyzed. When the current density was 12 mA / cm2, the initial pH was 6 and the reaction time was 20 min, the optimal removal efficiency of heavy metals and microplastics were obtained with removal rates of 95.16% and 97.5%, respectively. Under the condition of different current densities, the change of removal rate with time was fitted through mathematical model. The complexation forms of heavy metals and surface groups of microplastics were analyzed through pseudo-voltammetry curve. The operation cost of removing microplastics and heavy metals through IBPE reactor was 0.91 $·L−1 under the optimal experimental conditions. The experimental results suggested that this process reduced the potential harm of microplastics and heavy metals to aquatic organisms and human beings. The IBPE could be applied as a clean technology for simultaneous removal of microplastics and heavy metals from secondary effluent of WWTP.