Decoupling wastewater

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Urban wastewater treatment and reuse infrastructure play a vital role in achieving water sustainability; however, the pathways to realize water–climate synergies in planning such infrastructure are not clear. Here we examine the nexus of urban water stress and greenhouse gas (GHG) emissions resulting from expanding wastewater infrastructures across over 300 cities in China. We find that, despite a total increase of 176% in life-cycle GHG emissions, larger-scale wastewater treatment and reclaimed water reuse have nearly tripled the average amount of urban water stress alleviated between 2006 and 2015. However, with an extensive and integrated application of existing low-carbon technologies for wastewater treatment, sludge disposal and water reuse, it is possible to substantially further decouple water stress mitigation from GHG emissions by 2030. Under the optimized scenario, China can reduce wastewater-related emissions by 27% at the national level, while its eastern and northern cities could reduce emissions by over 40% for every unit of alleviated water stress. This study provides insights into the water–climate nexus and outlines feasible pathways to reduce water stress while mitigating wastewater-related GHG emissions.

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The programming code for the hybrid life-cycle model is available from the corresponding authors on request.

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This study was supported by the National Natural Science Foundation of China (72074232, 72091511, 71725005 and 71921003), Natural Science Fund for Distinguished Young Scholars of Guangdong Province, China (2018B030306032), Beijing Outstanding Scientist Program (BJJWZYJH01201910027031), the National Key Research and Development Program of China (2022YFF1301200), Major Project of National Social Science Fund of China (22&ZD108) and Jiangsu Provincial Department of Science and Technology (BK20220012). J.C.C. would like to acknowledge the support of the Brook Byers Institute for Sustainable Systems, Hightower Chair and the Georgia Research Alliance at the Georgia Institute of Technology. Z.L. would like to acknowledge the support of Hong Kong Research Grant Council (26201721). The views and ideas expressed herein are solely of the authors and do not represent the ideas of the funding agencies in any forms.

School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, China

Shaoqing Chen, Linmei Zhang & Feng Jiang

Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou, China

Shaoqing Chen, Linmei Zhang & Feng Jiang

State Key Laboratory of Pollution Control & Resource Reuse, School of Environment, Nanjing University, Nanjing, China

Beibei Liu, Hang Yi & Hanshi Su

The Johns Hopkins University–Nanjing University Center for Chinese and American Studies, Nanjing, China

Beibei Liu

Advanced Systems Analysis Group, International Institute for Applied Systems Analysis, Laxenburg, Austria

Ali Kharrazi

Global Studies Program, Faculty of International Liberal Arts, Akita International University, Yuwa City, Japan

Ali Kharrazi

Network for Education and Research on Peace and Sustainability (NERPS), Hiroshima University, Hiroshima, Japan

Ali Kharrazi

Division of Environment and Sustainability, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China

Zhongming Lu

School of Civil and Environmental Engineering and the Brook Byers Institute for Sustainable Systems, Georgia Institute of Technology, Atlanta, GA, USA

John C. Crittenden

State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Beijing Normal University, Beijing, China

Bin Chen

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S.C. and B.L. designed the research; L.Z., S.C. and H.S. performed the research; S.C., L.Z., H.Y., A.K. and F.J. analysed data; S.C., B.L., A.K., B.C., Z.L. and J.C.C. wrote the paper; and B.C. and J.C.C. reviewed and edited the manuscript.

Correspondence to Shaoqing Chen, Beibei Liu or Bin Chen.

The authors declare no competing interests.

Nature Water thanks Jing Meng, Qian Zhang and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Notes 1–5, Figs. 1–21 and Tables 1–12.

Sources of data used to perform this study.

Sources of data used to generate Fig. 1.

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Chen, S., Zhang, L., Liu, B. et al. Decoupling wastewater-related greenhouse gas emissions and water stress alleviation across 300 cities in China is challenging yet plausible by 2030. Nat Water (2023). https://doi.org/10.1038/s44221-023-00087-4

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Received: 07 August 2022

Accepted: 02 May 2023

Published: 01 June 2023

DOI: https://doi.org/10.1038/s44221-023-00087-4

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