GHG emissions reduction patterns from waste sectors after forced source separation

Waste management is the bridge to balance resource conservation and climate change protection, and source separation is the pre-requirement to improve the recycling rate and normal human behavior. In this work, greenhouse gas (GHG) emission patterns were investigated from waste sectors from 2016 to 2021 in Shanghai, where force MSW source separation was first implemented in China since 2019. The GHG emission in the waste sector increased from 3.06 (2016) to 9.28 (2021) Mt CO2-eq due to the increase of waste disposal amounts from 7.35 (2016) to 11.83 Mt (2021). With the implementation of forced source separation in Shanghai on July 1st, 2019, the proportion of kitchen waste and water content decreased by 37.31% and 20.74% in dry waste, resulting in the increase of low heating value (LHV) by 99.39% (13,160 kJ/kg). The waste disposal system was optimized by employing resource recycling and anaerobic digestion of wet waste, and the corresponding GHG emission intensity decreased from 0.29 to 0.24 t CO2-eq per ton MSW. Three scenario analyses, including the Business-As-Usual (BAU) scenario, New Policy (NP) scenario, and Low-carbon (LC) scenario, were conducted to study the influence of the grid emission factor, wet waste disposal capacity, incineration power generation efficiency, and lower waste plastic proportion on the GHG emissions. The results showed that the GHG emission intensity would reach 0.28, 0.21, and 0.12 t CO2-eq per ton MSW in the BAU, NP, and LC scenarios. Optimizing waste disposal mode and reducing waste plastic from sourced separation was critical to reduce GHG emissions more effectively from the waste sector