13. Comparative Analysis of Wastewater-Activated Sludge Recycling System in China: Environmental and Economic Performances

With the acceleration of the economic development and urbanization in China, wastewater generation has sharply increased. Previous studies mostly focused on the environmental and economic performances of wastewater-activated sludge reutilization (WASR), a biological treatment of wastewater that produces solid waste. However, policy impacts and comparative analysis integrating environmental, economic, and social performances of the applications to the potential resource recovery were ignored. Therefore, this study considered the following: (1) Environmental and economic performances of WASR scenarios, such as sludge-to-electricity, fertilizer, building material, and biogas, were evaluated by life cycle assessment and life cycle cost (LCC) approaches by replacing the traditional and similar commodities on the market with a system expansion. (2) The whole life cost of these scenarios was applied to include externality, which represents the monetization of emissions to integrate environmental and economic impacts. Major pollutants that contributed to the external costs of these scenarios were identified. The net present value of each WASR scenario was compared, which provided basis for technology improvements and policymaking. (3) Through an LCC of policy scenario analysis, we found that waste disposal subsidy was vital for WASR than the corporate income tax and environmental protection tax. Finally, an evaluation system of WASR integrating environment, economy, and policy aspects was proposed, which provided references for governments and industries. Consequently, future perspectives of sludge reutilization in China and suggestions on sustainable sludge recycling systems for developing countries were deduced.