Environmental and economic evaluation of a mechanical biological treatment system for a small and medium-sized waste treatment facility considering the karatsu smart disaster-resilience base construction project

We evaluated the feasibility of waste-generated heat using a 100-kW digestion gas engine at the Karatsu City Water Purification Center by evaluating its disaster resilience through four indicators. We achieved the best outcome, i.e., a power generation rate of 1,122 kW and a power self-sufficiency rate of 22% when two or more digestion gas engines were installed to supply waste-generated heat to the absorption chiller/heater of a water-pool. Additionally, we evaluated the environmental and economic aspects of a Mechanical Biological Treatment (MBT) system installed in Karatsu City. The results suggested that by installing an MBT system, the annual cost could be reduced by ∼100 million Yen and the power generation capacity could be increased to 4,310 kW; this could also help reduce 19,000 tons of annual CO₂ emissions with increased power generation. The environmental and economic feasibility assessment tool developed here is configurable; hence, applicable to other regions.