Assessing the Economic and Environmental Impacts of Anaerobic Digestion for Municipal Organic Waste: A Case Study of Minamisanriku Town, Japan

Anaerobic digestion (AD), or biogas technology, is an optimal method for municipal organic waste (MOW) treatment, recovering both material and energy. This study takes a life cycle assessment perspective and examines the economic and environmental impacts of a BIO facility in Minamisanriku Town, Japan, which has utilized MOW (kitchen/food waste and surplus sludge from sewage) as local biomass resources since 2012. Stakeholder interviews were conducted to gather data on material flows and impacts. Scenario analysis considered various conditions, such as pre- and post-operation of the BIO facility, the use and non-use of digestate as liquid fertilizer, and the facility's 100% operational efficiency. The results indicate that full operation of the BIO facility and marketing of value-added products, such as branded rice grown using liquid fertilizer, could significantly reduce greenhouse gas (GHG) emissions, lower integrated environmental costs, improve the regional economy, and increase net income. In the business as usual (BAU) scenario with a 56% operation rate of the BIO facility, there is an over 10% improvement in economic and environmental impacts compared to the pre-operation baseline. This study underscores the importance of maximizing biomass utilization to develop value-added uses by enhancing, extending, and expending stakeholder collaboration.