Sustainable in situ ammonia recovery from municipal solid waste leachate in a single-stream microbial desalination...

Municipal solid waste (MSW) leachate is one of the most hazardous waste streams leading to great potential risk to environment, and a renewable resource with high concentrations of organic contaminant and ammonia. High energy consumption and chemical input are still the challenges for ammonia recovery from MSW leachate. Here, a single-stream microbial desalination cell (SMDC) was successfully developed for simultaneous energy extraction from organic contaminant and in-situ energy utilization for ammonia recovery. 70% of the organic contaminant from the actual MSW leachate was removed, and 24.9% of the total ammonia was recovered as high-purity (NH₄)₂SO₄. The additional desalination chamber introduced into the SMDC can potentially enhance the NH₄⁺ migration that was determined by the NH₄⁺ concentration gradient and electric field. More than 30% of the total nitrogen was lost, as revealed by nitrogen mass balance analysis, probably resulting from the anodic denitrification process driven by denitrifying microorganisms, e.g., Thauera, which thrived in the anode chamber. Concomitantly, the chemical input for ammonia stripping can be reduced by up to 68% due to the relatively low buffer capacity of the catholyte and the OH^- production from the cathode reaction. This SMDC can be an effective and environmentally sustainable solution for MSW leachate treatment and resource recovery.