Abstract
The moving bed biofilm reactor (MBBR) is a cornerstone technology in modern wastewater treatment, yet its performance is often hindered by carrier clogging, which significantly reduces overall treatment efficiency and undermines the technology’s environmental benefits. Here, we introduce a V-carrier hydro-topological design strategy that enables biofilm self-regulation, allowing simultaneous control of biofilm thickness and continuous hydraulic shear-induced self-cleaning. In a pure biofilm system treating real municipal wastewater for over 500 days, the V-carrier achieves stable and efficient nutrient removal even under low-temperature (9.1 °C) and high-loading conditions. Crucially, it achieves a 3.2-fold higher unit biomass nitrification rate with a biofilm biomass 44% lower than a conventional K3 carrier, demonstrating that treatment efficiency is decoupled from biomass quantity through optimal ecological niche design. This work establishes a paradigm for biofilm reactor design, transforming carriers from passive substrates into active regulators of microbial ecosystems, with profound implications for sustainable water infrastructure.
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Data availability
The data generated in this study are provided within the article and its Supplementary Information. Raw sequence data have been deposited in the China National Center for Bioinformation (CNCB) database under BioProject accession number CRA032524 and are publicly accessible at: https://ngdc.cncb.ac.cn/gsa/browse/CRA032524. Source data are provided with this paper.
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Acknowledgements
This research was supported by National key R&D Program of China (2024YFD2400100; Y.L.), the scientific research project in Fengjiawan of Hainan Provincial Seed Industry Laboratory (B24H10035; Y.L.), the National Natural Science Foundation of China (Grant No. 31971794; K.S.), the Fundamental Research Funds for the Central Universities 226-2025-00074; Y.L., China Agriculture Research System of MOF and MARA (CARS-49; Y.L.), Key Research & Development Projects of Zhejiang Province (2025C02203; K.S.), and Student Research and Entrepreneurship Project of Zhejiang University (2023; K.S.).
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Y.F., Y.L., and K.S. conceived the idea and designed the research. Y.F. and Z.Z. conducted the experiments, collected and interpreted the data. Y.F., Z.Z., B.X., and K.S. prepared the figures, wrote and edited the manuscript and supplementary information. Y.L. and K.S. jointly oversaw the administration of the project and supervised the work. All the authors discussed the results and commented on the paper.
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Fang, Y., Zhang, Z., Xue, B. et al. A hydro-topological strategy enables self-regulating biofilms for sustainable wastewater treatment. Nat Commun (2026). https://doi.org/10.1038/s41467-026-70682-y
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DOI: https://doi.org/10.1038/s41467-026-70682-y
