Energy-efficient for advanced oxidation of bio-treated landfill leachate effluent by reactive electrochemical membranes (REMs): Laboratory and pilot scale studies

Abstract

This study for the first time investigated the advanced treatment of bio-treated landfill leachate effluent using a novel reactive electrochemical membrane (REM) technology at the laboratory and pilot scales. At the laboratory scale, RuO2-Ir-REM, Ti4O7-REM, and β-PbO2-REM featured similar properties in pore size and water flux. Although RuO2-Ir-REM holds more reactive sites than the other two REMs, β-PbO2-REM and Ti4O7-REM featured higher oxidation ability than RuO2-Ir-REM, causing their high yield of hydroxyl radical. Consequently, β-PbO2-REM and Ti4O7-REM performed better than RuO2-Ir-REM, which removed total organic carbon and ammonia nitrogen by 70%–76% and 100%, respectively, after 45 minutes of treatment. Fluorescence spectroscopy analysis showed that humic acid-like substances were oxidized by the REM treatment. Using the β-PbO2-REM in the lab-scale setup with the solutions circulated, we observed a greater removal of chemical oxygen demand (COD) at a higher applied current or a faster water flux. The pilot system with four large size of β-PbO2-REMs modules in series was developed based on the lab-scale setup, which steadily treated landfill leachate in compliance with the disposal regulations of China, at an energy consumption of 3.6 kWh/m3. Also, a single-pass REM can effectively prevent the transformation of chloride to chlorate and perchlorate. Our study showed REM technology is a powerful and promising process for the advanced treatment of landfill leachate.