Abstract
In local cities with decentralized small wastewater treatment plants (WWTPs), centralized anaerobic digestion at a WWTP that accepts more sludge from others can serve as the energy hub of the region. Oxidation ditch processes are widely used in small facilities, and dewatering sewage sludge makes it easier to transport the sludge to a centralized WWTP. The applicability of dewatered sewage sludge to anaerobic digestion with simple operation was investigated by continuous and batch experiments. Biogas production of sewage sludge was 0.1-0.2 NL/gVS-added, and that from kitchen garbage was 0.7 NL/gVS-added. Codigestion of sewage sludge and kitchen garbage had synergistic effect on biogas production. Operational energy consumption was reduced by simple operation such as reduced withdrawal frequency and mixing of the digested sludge. A cultural test confirmed that the digested sludge can be used as a fertilizer.
