Treatment of Landfill Leachate by Combined Submerged Membrane Bioreactor (SMBR) and Electrochemical Oxidation

To efficiently treat landfill leachate, we prepared a new integrated submerged membrane bioreactor (SMBR) and oxidation technology. Our results, under organic loading rates of 2.0–2.3 kg COD/(m3 ·d), showed that through SMBR we can acquire removal efficiencies of 91.2% and 87.3% for ammonia and chemical oxygen demand (COD), respectively. A Ti/RuO2–IrO2 anode and stainless-steel cathode combination was engaged to carry out electrochemical oxidation of SMBR permeate. Ammonia and COD were removed after 3 h electrochemical oxidation (at 40 mA/cm2 current density), and achieved 93.5% and 66.9% removal efficiency with activated carbon particle electrode introduced in the three-dimensional electrodes, respectively. The higher removal efficiency for ammonia nitrogen than COD can be rendered by excited chloride ions, as they affect the competition between organic matter and ammonia nitrogen. Thus, SMBR combined with electrochemical oxidation possesses good prospects to be applied for efficient reduction of ammonia and COD in landfill leachates.