Comparison and Selection of Wet Waste Disposal Modes for Villages in Agriculture-Related Towns Taking Shanghai, China, as an Example

Under the increasingly stringent regulatory constraints, wet waste disposal in agriculture-related towns has become a significant issue. Based on fieldwork in three agriculture-related towns and nine villages located in Shanghai, this paper analyzes the economics and greenhouse gas emissions of three wet waste disposal methods, including centralized disposal, on-site disposal by biogas digesters, and on-site disposal by small-scale biochemical processors, and compares these alternatives by combining various factors, aiming to help decision makers in selecting the optimal alternative. The net present value approach was employed to evaluate the economic aspects of the three disposal methods. The greenhouse gas emissions were calculated using life cycle assessment, life cycle inventory, and the IPCC guidelines. The fuzzy analytic hierarchy process method was employed for a multi-criteria decision-making analysis based on five factors, including economics, greenhouse gas emission control, stability, compliance with environmental regulations, and location feasibility. The results revealed that although centralized disposal is not as good as on-site disposal by biogas digesters in terms of economics and greenhouse gas emissions, centralized disposal is still the optimal alternative according to the results of multi-criteria decision making. The tightening of regulatory constraints will internalize the negative externalities of on-site wet waste disposal. Thus, centralized disposal is the method of wet waste disposal that is most consistent with the regulatory constraints and most sustainable. It is worth emphasizing that policymakers should fully assess the impact of tightening regulations on the selection of wet waste disposal methods, establish a homogenous waste disposal system covering both urban and rural areas, and enhance the management of existing on-site disposal facilities.