Effective bio-treatment of fresh leachate from pretreated municipal solid waste in an expanded granular sludge bed bioreactor

This research investigated the anaerobic biodegradation of fresh leachate from pretreated municipal solid waste (MSW) in an expanded granular sludge bed (EGSB) bioreactor under mesophilic conditions. The observations showed that this bioreactor, inoculated with anaerobic granular sludge, could be readily activated. The chemical oxygen demand (COD) removal efficiency varied between 88% and 97% under normal operation conditions, and was kept at 94-96% under the proposed optimal conditions. We noted that 60-80% of the produced biogas was methane that was yielded at a rate depending on the organic loading rate (OLR) and the liquid up-flow velocity (Vup). Significantly, 80% of loaded COD or 83% of biodegraded COD was converted to methane under the proposed optimal conditions. These findings indicate that the fresh leachate from pretreated MSW can be efficiently treated in the EGSB bioreactor, and moreover, methane, a renewable energy, can be continuously generated. (C) 2009 Published by Elsevier Ltd.