Iron-carbon micro-electrolysis and anaerobic-aerobic activated sludge integrated process for treating landfill leachate: Process optimization, stability, and mechanism

A novel process combining iron-carbon (Fe-C) modified fillers with activated sludge in a reactor was introduced to enhance leachate treatment efficiency. The study focuses on optimizing the preparation methods of fillers and assessing the impact of various factors, such as hydraulic retention time, initial pH, biological iron-to-carbon ratio, and dissolved oxygen content. Under optimized conditions, remarkable removal efficiencies were achieved: 68 % for chemical oxygen demand, 83 % for total phosphorus, 71 % for ammonia nitrogen, and 67 % for total nitrogen. Long-term operations mirrored these results. Results from three-dimensional excitation and emission matrix fluorescence spectroscopy demonstrated the synergistic degradation of insoluble fulvic acid-like and humic acid-like substances. Microbial community analysis indicated that Fe-C promotes autotrophic denitrification, while X-ray diffraction spectroscopy revealed the mechanisms of chemical phosphorus removal via iron and struvite. Therefore, a technology involving micro-electrolysis and activated sludge was proposed, offering a potential strategy for the treatment of landfill leachate.