The effect of microbial electrolysis cell coupled with anaerobic digestion for landfill leachate treatment

Landfill leachate contained high salinity and refractory organic compounds, poses significant challenges for treatment. The microbial electrolysis cell coupled with anaerobic digestion (MEC-AD) offers an effective solution by enhancing current transfer and improving electrochemical treatment efficacy across different salinity. The effects of landfill leachate salinity (5-40 g/L) on both MEC-AD and AD were investigated in this study. The findings revealed that at 10 g/L of NaCl concentration, the MEC-AD achieved 37 % of COD removal rate. Furthermore, even when the NaCl concentration was increased to 24 g/L and 40 g/L, MEC-AD continued to outperform AD. In MEC-AD, the complementary cyclic voltammetry (CV) demonstrated that increased salinity enhances the electrochemical activity and electron transfer capacity of the anode biofilm. Additionally, microbial community analysis revealed progressive shift in the dominant microbial phyla from Firmicutes (26 %) and Chloroflexi (22 %) to Proteobacteria (23-39 %), Chloroflexi (25-39 %), and Bacteroidota (10-21 %).