Supplementary file 1_Greenhouse gas accounting of municipal solid waste (MSW) treatment integrating classification and synergistic valorization of characteristic wastes: a case study of Zhanjiang, a Coastal City in South China.docx

Optimizing MSW classification and treatment is crucial for achieving carbon neutrality, especially in coastal cities with unique waste streams.</p>Methods<p>Using life‐cycle assessment, we quantified direct, indirect, and avoided‐product emissions for five MSW scenarios in Zhanjiang, China, including food waste (FW) anaerobic digestion (AD), black soldier fly (BSF) bioconversion, recyclable recovery, and shell‐waste valorization into bio‐CaCO₃.

The functional unit was 1 tonne of MSW.</p>Results<p>Net emissions were negative for all scenarios (−512 to −682 kg CO₂_eq/t). The integrated scenario (20% FW separation, 30% recyclables, BSF treatment, and 5% shell valorization) achieved the lowest net emission (−681.54 kg CO₂‐eq/t), a 33% reduction from baseline. Shell valorization contributed 23% of the incremental benefit.</p>Discussion<p>Moderate separation rates (20–30%) offer optimal balance; exceeding thresholds yields diminishing returns.