Carbon emission reduction potential of municipal solid waste treatment and disposal at different management stages: a case study of Xiamen City

The rapid urbanization has generated a large amount of municipal solid waste (MSW) in China. In order to address the universal issue of garbage siege, China continues to improve the MSW management system. It has undergone different stages of development, such as landfill-based harmlessness, incineration-based harmlessness and reduction, comprehensive promotion of compulsory classification of garbage in major cities, and the comprehensive treatment and disposal of classified garbage. Taking Xiamen City as an example, the carbon emissions and characteristics of different MSW management stages were studied and analyzed. The results showed that the total amount of carbon emissions in Xiamen from 2000 to 2009 (harmlessness stage) increased from 254 900 t to 763 800 t, with an average annual growth of 13.19%. From 2010 to 2016 (harmlessness and reduction stage), the carbon emission intensity per ton of waste decreased each year due to the improvement of landfill gas collection efficiency and the continuous promotion of waste incineration reduction. However, the total emissions still increased from 279 500 t to 493 000 t. Since 2017, the city has implemented the four classifications of garbage, carried out the classification of kitchen waste, and built a pilot project for low-value recyclables. The carbon emission intensity has decreased from 324.74 kg/t to 178.11 kg/t, and the carbon emissions per ton of food waste, recyclables, kitchen waste and low-value recyclables were reduced by 5.69, 302.58-328.75, 83.19, and 884.66 kg, respectively. In the future, with the promotion of low-value recyclables classification and the construction of renewable resource centers, the carbon emission intensity and total amount of domestic waste will be further reduced, promoting the city's green and low-carbon development.