Environmental and Economic Evaluation of Mechanical Biological Treatment System for Municipal Waste Considering the Political Framework in Ichihara City

Japan’s declining population has caused changes in the amount and characteristics of municipal waste. In order to optimize waste incineration plants as a countermeasure to this problem, we analyzed the performance of the integration of the plants with the Mechanical Biological Treatment (MBT) system. In the integrated system, food waste and sewage sludge from waste incineration plants, sewage treatment plants, and industrial facilities were mixed and fermented to produce methane gas. In this study, we evaluated the environmental and economic performance of the integrated system in four case scenarios. The integrated system is located in Ichihara City in Chiba Prefecture, where the Keiyo Coastal Industrial Zone is located and where petroleum and chemical industries are concentrated. The MBT system in which the heat generated from the incineration of waste was transferred to the Keiyo Coastal Industrial Zone was found to be the best. This method could reduce CO₂ emissions by 1341 t-CO₂/Y, and the annual cost was the lowest at 1.60 billion yen/Y. However, the results of the sensitivity analysis of the food waste ratio and the piping distance suggested that it may be impossible to obtain appropriate evaluation results without considering the regional characteristics.