Sub-theme
2. Promoting Water Efficiency, Productivity and Services
Topic
2-4. Wastewater treatment and reuse
Body
The rapid development of municipal wastewater treatment in recent decades has made positive contributions to water environment in China, which, however, consequences in high carbon emission through advanced wastewater treatment process. Under the carbon emission peaking and neutrality targets, it is essential to formulate optimization pathways towards co-benefit of environment improvement and carbon reduction. In this study, major contributors of GHGs in typical municipal sewage treatment systems in China were analyzed, followed by main factor analysis affecting total GHG emissions in different regions, as well as the proposal for optimization pathways for typical municipal wastewater treatment systems. Two provinces with representative climate condition, urbanization progress and economic development was selected from northern and southern China respectively, which were Hebei Province and Guangdong Province, on which case study was carried out based on the actual situation of their municipal wastewater treatment systems. GHG emission accounts of municipal wastewater treatment system in two provinces were established, based on the activity data of sewage treatment, statistical data of urban population and sewer construction in 2020, using IPCC equation and localized emission factors. The composition and driving factors of GHG emissions were compared and analyzed, combined with statistical and literature research methods. The result revealed certain differences in major contributors of GHG emissions between the two provinces, among which sludge disposal in Hebei Province had a significant contribution to the total GHG emissions, while the emissions of sewage collection system in Guangdong Province were more prominent. It was greatly related to the sludge disposal structure dominated by sludge landfill in northern China, as well as the ineffective sewer network in the southern area with sufficient precipitation. In both provinces, indirect emissions of carbon dioxide, e.g. energy consumption, contributed a large proportion of GHG emission, indicating that energy-saving technologies and efficient operation of treatment facilities was still an important measure. This study suggested that adjusting the mainstream sludge disposal methods in northern China and increasing the sewage collection rate through rainwater diversion and pipeline repair in southern China could optimize the municipal wastewater treatment system in different regions, achieving sustainable synergistic effects of urban pollution mitigation and carbon reduction.