Toward sustainable waste systems: Does China's mandatory waste separation pilot policy promote the eco-efficiency of...

To address the growing challenge of municipal solid waste (MSW) generation, China has implemented mandatory waste separation pilot (MWSP) policy since 2017. However, empirical evidence regarding the effectiveness of the MWSP policy in the context of enhancing environmental performance remains limited. This study uses panel data concerning 284 Chinese cities from 2011 to 2020 and a super-efficiency slacks-based measure (SBM) model with undesirable outputs to evaluate the eco-efficiency of MSW management. Furthermore, we examine the direct and spatial effects of the MWSP policy and its moderating mechanisms and heterogeneity based on difference-in-differences (DID) and spatial DID (SDID) models. The empirical results indicate the following: (1) The MWSP policy significantly promotes the eco-efficiency of MSW management in pilot cities and enhances eco-efficiency in neighboring cities through spatial spillover effects, which are robust across multiple tests. (2) Environmental regulation and public environmental concern significantly moderate the impacts of the MWSP policy, thereby strengthening the positive effect on the eco-efficiency of the policy. (3) A heterogeneity analysis reveals that the total effect of the MWSP policy is more pronounced in the central and western regions of China as well as in smaller cities, whereas eastern cities are associated with stronger spatial effects. These findings suggest policy and management recommendations regarding efforts to promote the implementation of the MWSP policy and transition to sustainable waste systems in China.