Carbon Footprint And Emission Reduction Potential Of Different Waste Disposal Modes Under The Background Of Waste Classification

Climate change and ecological environment problems caused by the greenhouse effect are serious challenges facing mankind in the 21st century.As an important source of greenhouse gas emissions,reducing greenhouse gas emissions from domestic waste disposal units is of great significance for China to achieve the goal of carbon peak and carbon neutralization.Traditional domestic waste disposal is mainly based on landfill and incineration,but with the gradual implementation of municipal solid waste classification in China,the amount of waste generated,composition,and characteristics of waste will change.Furthermore,the process of waste collection,transportation,end-of-pipe treatment and disposal will also be significantly different from those of traditional waste treatment and disposal process,resulting in noteworthy differences in GHG emissions.Therefore,this study aims to explore the carbon footprint of the entire waste disposal process in Qingdao under various classification scenarios and clarify the impact of waste classification on GHG emissions,using the IPCC inventory model,and based on a comprehensive understanding of the GHG emission laws of waste disposal in Qingdao,alongside the implementation of waste classification inthe city,utilizing the whole-life cycle assessment method.Based on this,reduction measures of GHG emission in the process of waste treatment and disposal are put forward.Overall,The results of the study will be of great significance for reducing the GHG emissions in waste disposal process and guiding waste classification in China.The main research conclusions are as follows:（1）Using the IPCC inventory model,the GHG emissions of municipal solid waste（MSW）disposal units in Qingdao were estimated from 2010 to 2020,and the results showed that GHG emissions（in terms of CO₂-eq）increased from 1.313 million t in 2010to 2.2378 million t in 2016 and decreased to 950.5 million t in 2020.Landfill is the main source of GHG emissions until 2019,while incineration becomes the most important source of GHG emissions in 2020,accounting for 94.84%.（2）GHG emissions per unit of GDP in Qingdao decreased from 24.53 kg CO₂-eq/10,000 yuan in 2010 to 7.58 kg CO₂-eq/10,000 yuan in 2020.GHG emissions per capita decreased from 150.65kg CO₂-eq/person in 2010 to 94.06kg CO₂-eq/person in 2020.（3）The net carbon emissions of the entire waste disposal process varied significantly by waste disposal mode.The net carbon emissions of the four modes（Mode 1 is mixed collection+landfill;mode 2 is mixed collection+incineration;mode 3 is classified collection+anaerobic fermentation of kitchen waste+incineration of other wastes;mode4 is classified collection+anaerobic fermentation of kitchen waste+recycling of recyclable waste+incineration of other wastes）were ranked from highest to lowest as follows:Mode 1>Mode 3>Mode 2>Mode 4.The ideal waste classification and treatment mode had a net carbon emissions of-226.1 kg CO₂-eq/t,which significantly reduced CO₂ emissions compared to the traditional mixed collection and transportation mode.（4）The net carbon emissions were linearly related to the food waste sorting efficiency,with each 20%increase in food waste separation efficiency increasing net carbon emissions by about 13.6 kg CO₂-eq/t.Improving the food waste recycling efficiency does not reduce carbon emissions.As the waste recycling efficiency increased,the carbon reduction increased linearly.For every 10%increase in the recycling efficiency of recyclable waste,the net carbon emissions decreased by about 28.56 kg CO₂-eq/t.Moderately separating food waste,improving the efficiency of recycling recyclable waste,and reducing the anaerobic digestion methane leakage rate of food waste are feasible strategies for reducing GHG emissions and social costs.