Greenhouse gas emissions from municipal solid waste with a high organic fraction under different management scenarios

Waste management is a major source of greenhouse gas (GHG) emissions and provides an opportunity to reduce carbon emissions that has yet to be fully exploited. The total GHG emissions in the waste management sector in China is quite different from that in developed countries, mainly due to the high biodegradable fraction (almost 60-70%) of municipal solid waste (MSW). Based on the above characteristics of MSW and its current and future management strategies, five typical scenarios were modeled by the EaseTech software to compare GHG emissions under different scenarios. These strategies were evaluated by life cycle assessment (LCA) and sensitivity analysis. The two scenarios of landfilling, either with LFG flaring or with LFG to energy, would cause very high GHG emissions (259.5 kgCO2-Eq/t and 169.0 kgCO2-Eq/t, respectively) due to the rapid degradation and low efficiency of landfill gas (LFG) collection. Incineration with energy recovery would lower total GHG emissions (−17.5 kgCO2-Eq/t) substantially. However, the auxiliary fuel needed would offset its environmental benefit. Two scenarios, anaerobic digestion (AD) of the source-separated organic fractions and residue landfilling, and AD of the source-separated organic fractions and incineration of the fractions with high calorific value, followed by residue landfilling, would result in significant carbon sinks (−27.7 kgCO2-Eq/t and −54.8 kgCO2-Eq/t, respectively). From the perspective of GHG emissions reduction, the optimum technical route of MSW in China would be AD of the source-separated organic fractions, incineration of the fractions with high calorific value, followed by residue landfilling.