Electrocoagulation applied for the removal of microplastics from wastewater treatment facilities

Abstract

• Electrocoagulation was tested for the removal of microplastics. • In real wastewater samples, microplastic removal efficiencies of 98.6% were achieved. • Results showed that the electrocoagulation process is an effective process for microplastic removal. • The blanket sludge floated after the electrocoagulation could be easily removed by overflow or skimming. This study evaluated the efficacy of electrocoagulation methods for the removal of microplastics using both synthetic solutions and wastewater samples. The experiments were performed with commercial polyester microplastic in batch reactors. Current density (1.92–8.07 mA/cm 2 ), pH (2–7), microplastic size range (25–1500 μm), and electrolysis time (0–90 min) were the variables used to assess the process. When using synthetic solutions with pH values of 4 and 7 and current densities of 2.88 and 8.07 mA/cm 2 , the microplastic removal efficiency was at least 99% in all cases. Measurement of Particle Image velocity (PIV) and analysis of Scanning Electron Cryomicroscopy (Cryo-SEM) were used as monitoring tools for tracking the activity of the hydrogen gas bubbles. The lowest estimated operational costs were obtained by using a current density of 2.88 mA/cm 2 and an initial pH of 4. Using real wastewater samples, the removal efficiency of microplastics was 96.5%. In addition, 92.2% of COD and 88.8% of thermotolerant coliform colonies were removed. The results of the study showed that electrocoagulation effectively can remove microplastics from wastewater streams at low operational costs while simultaneously reducing both COD and thermotolerant coliforms.