Leachate post-treatment by electrocoagulation process: Effect of polarity switching and anode-to-cathode surface area

In the electrocoagulation process, passivation or corrosion of the electrodes is one of the biggest challenges that cause a drop in treatment effectiveness. In this study, the effect of polarity switching was investigated, for the first time, in an attempt to enhance electrocoagulation treatment's ability to remove chemical oxygen demand (COD) and color from pretreated landfill leachate. Moreover, the ratio of the anode to cathode surface area and rotating electrode were examined in light of experimental results. The effect of different parameters, including the stirring speed, initial leachate pH, electrical current density, anode to cathode surface area ratio, and polarity switching time on system efficiency, was evaluated using the one-factor-at-a-time (OFAT) classical method. According to the results, polarity switching resulted in an almost 18% increase in COD removal, 14% increase in color removal, 13% decrease in electrical energy consumption (EEC), 51% decrease in the specific sludge production (TSS/COD), and improved electrode performance compared to non-polarity switching mode. The findings of this research showed the highest COD and color removal efficiencies, which were 34% and 67%, respectively, in a 120 min period, a stirring speed of 135 rpm, the initial leachate pH of 9, the current density of 14.4 mA/cm(2) , the anode/cathode surface ratio of 0.35, and the polarity switching time of 300 s.

Automated summary

The study demonstrated that polarity switching in electrocoagulation process can improve COD and color removal efficiency, reduce energy consumption and specific sludge production. Under specific conditions (e.g., stirring speed of 135 rpm, initial pH of 9, current density of 14.4 mA/cm(2), anode/cathode ratio of 0.35, polarity switching time of 300 s), the highest COD removal efficiency of 34% and color removal efficiency of 67% were achieved within a 120-minute period.