LI C J , HUANG S, CHEN B G, et al.Carbon footprint analysis and assessment of municipal wastewater treatment based on life cycle assessment[J].Journal of Henan Polytechnic University(Natural Science) ,2026,45(1):40-48.

doi:10.16186/j.cnki.1673-9787.2025080038

Received:2025/07/22

Revised:2025/09/20

Published:2025-12-03

Carbon footprint analysis and assessment of municipal wastewater treatment based on life cycle assessment

Li Chengjie1,2, Huang Sen3, Chen Baoguang4, Zhao Aiping5, Guo Xiaoming1,2, Jiang Fengcheng1,2, Wang Mingshi1,2

1.School of Resources and Environment， Henan Polytechnic University， Jiaozuo  454000， Henan， China；2.Henan Key Laboratory of Coal Measure Unconventional Resources Accumulation and Exploitation， Jiaozuo  454000， Henan， China；3.China Classification Society Quality Certification Co.， Ltd. Beijing  100006， China；4.Witep Tech Co.， Ltd.， Zhengzhou  450041， Henan， China；5.Kangda Environmental Protection （Jiaozuo） Water Co.， Ltd.， Jiaozuo  454000， Henan， China

Abstract: Objectives Gaps in existing wastewater treatment carbon-footprint research are addressed in the present study—namely the omission of CO₂ emissions originating from fossil-derived organic carbon in influent wastewater that are released during biological treatment by activated sludge， and the lack of comprehensive life-cycle-level evaluation of carbon-reduction pathways. A life-cycle assessment is conducted to analyze and evaluate the carbon footprint of municipal wastewater treatment. Methods An improved carbon-footprint accounting model is developed to identify the key emission sources across the full process of representative A/A/O （anaerobic/anoxic/oxic） wastewater treatment plants， and integrated， system-level mitigation strategies are proposed. Taking a typical wastewater treatment plant as a case study， a life cycle assessment （LCA） method is applied to establish a system encompassing four unit processes： primary treatment， biological treatment， advanced treatment， and sludge treatment. The eFootprint software， along with the CLCD and Ecoinvent databases is used to quantify the carbon footprint. A novel aspect includes the accounting of CO₂ emissions derived from fossil-origin organic carbon in wastewater during biological treatment via the activated sludge process. Based on one year of actual operational data， a sensitivity analysis is conducted to identify key influencing factors. Results The total carbon footprint of the plant is found to be 5.11×10⁻¹ kg CO₂e/m³. The carbon footprint of the four unit processes is ranked as follows： biological treatment>sludge treatment>advanced treatment>preliminary treatment. Biological and sludge treatments together account for 73% of the total， identifying them as the primary carbon emission units. From an inventory perspective，the contributions are ranked as follows： electricity consumption>material consumption>pollutant emissions>direct emissions. Electricity and material consumption are identified as the core influencing factors， with indirect emissions collectively accounting for 82%. Conclusions Based on the carbon footprint accounting model constructed in this study， which incorporates fossil-derived CO₂ emissions， biochemical treatment and sludge treatment have been identified as the key units for emission reduction， with electricity consumption and material consumption being the primary focuses for management. Accordingly， short-and long-term coordinated emission reduction strategies are proposed： short-term measures include improving equipment energy efficiency， optimizing operational processes， and adopting low-cost material alternatives； long-term strategies involve process upgrades， implementing intelligent control systems， and optimizing the energy mix. This approach provides actionable pathways for carbon emission reduction in wastewater treatment plants.

Key words:life cycle assessment;wastewater treatment;carbon footprint;carbon emissions;carbon mitigation pathways;unit process analysis