Abstract
To reconcile the resource recovery and decarbonization trade-off in industrial wastewater treatment while meeting the United Nations Sustainable Development Goals, this study deciphers the operational mechanisms of globally representative steel-industry net-zero-liquid discharge (NZLD) system (220 m3/h) to propose a hierarchical four-stage framework. We reveal that Cl–/SO42- competition dynamically regulates nanofiltration membrane selectivity, while establishing quantitative links between oxygen atom signatures of dissolved organics and product purity. An experimentally-derived salinity-driven trade-off emerges: high salt levels enhance ion separation but suppress organic degradation due to radical scavenging. Life cycle impact assessment pinpoints carbon hotspots and demonstrates an 81.8% footprint reduction via renewable electricity. Under modelled scenarios, scaling this framework to treat China’s annual 1.50 billion m3 applicable Na+/Cl–/SO42--dominated high-salinity wastewater could potentially recover 1.43 billion m3 water, 8.11 million tonnes NaCl, and 5.09 million tonnes Na2SO4, saving USD 3.68 billion annually. This strategy provides a transferable blueprint for low-carbon resource recovery globally.
Acknowledgements
The authors gratefully acknowledge the technical support, operational assistance, and facilities provided by Baowu Group Environmental Resources Technology Co., Ltd. during the long-term field sampling and data collection.
Funding
This research was financially supported by the National Natural Science Foundation of China (No. 52270076).
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Chu, H., Lu, L., Song, W. et al. Hierarchical net-zero-liquid discharge approach for sustainable salt recovery and carbon footprint reduction in steel wastewater treatment.
Commun Eng (2026). https://doi.org/10.1038/s44172-026-00764-8
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DOI: https://doi.org/10.1038/s44172-026-00764-8
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