Towards sustainable municipal solid waste treatment: Life cycle environmental-economic analysis under waste sorting

Municipal solid waste (MSW) treatment is a significant contributor to greenhouse gas (GHG) emissions globally. The implementation of MSW classification policies is reshaping waste disposal strategies, particularly in China under the "Dual Carbon" targets. This study employed an integrated life cycle assessment and life cycle cost (LCC) framework to evaluate the environmental and economic performance of waste disposal under both current and idealized MSW sorting scenarios in Qingdao, China. Furthermore, scenario simulations were conducted to explore optimization pathways. The results indicate that MSW disposal under the baseline scenario (S0) resulted in net-negative carbon emissions (-159.18 kg CO₂-eq/t MSW) due to energy recovery, while also achieving substantial reductions in terrestrial ecotoxicity and human non-carcinogenic toxicity. The ideal waste sorting scenario (S1) offered significant environmental benefits, with GHG emissions reduced to -355.88 kg CO₂-eq/t MSW. However, its practical implementation remains constrained by capital investment and labor demands. Compared to S0, the optimized scenario (S2) improved environmental performance, reducing GHG emissions by 10.69 kg CO₂-eq/t MSW through better recyclables recycling, thermal energy use, and biogas upgrading. The weighted endpoint resource impact decreased from -5.61 Pt to -6.85 Pt. Moreover, the dynamic LCC evaluation revealed that S2 increased economic benefits by 85.36 % relative to S0. Our study provides insights into optimizing waste treatment pathways to reduce environmental impacts, enhance economic performance, and support low-carbon transition. It also offers quantitative evidence for sustainable management and practical strategies for MSW managers.