Solar-driven sewage sludge electroreforming coupled with biological funnelling to cogenerate green food and hydrogen | Nature Water

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The ever-increasing generation of sewage sludge in megacities places a substantial burden on waste treatment systems. The complex and resilient structure of sludge renders conventional pretreatment and biological reclamation methods time-consuming, energy-inefficient and environmentally burdensome. Here we present an integrated mechano-electro-bioprocess that valorizes sludge with minimal environmental impact. We achieve nearly complete recovery of organics with ~91.4% total organic carbon (TOC), which are effectively converted into single-cell protein (>63% TOC) in a tandem process. Heavy metals are efficiently concentrated and stabilized, while simultaneously producing green hydrogen at an impressive efficiency and rate (~10% solar-to-hydrogen energy efficiency, rate >13 l per hour). A comprehensive life-cycle and techno-economic analysis confirms the substantial environmental and economic benefits of this approach. Notably, it results in a 99.5% reduction in CO2 emissions and a 99.3% decrease in energy depletion compared with conventional anaerobic digestion. As renewable electricity deployment expands globally, this mechano-electro-bioprocess offers a promising path towards sustainable development.

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This work was supported by A*STAR Science and Engineering Research Council AME IRG funding (A1983c0029, H.L.) and the National Research Foundation, Prime Ministers Office, Singapore under its Campus for Research Excellence and Technological Enterprise (CREATE) programme (award number NRF2022-ITC004-0001, H.L.). We acknowledge the Facility for Analysis, Characterization, Testing and Simulation (FACTS), Nanyang Technological University Singapore for use of electron microscopy and X-ray facilities and L.M. Shan and A.K.J. On from NEWRI Analytics Cluster, Nanyang Technological University, Singapore, for their guidance on product analysis.

School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore, Singapore

Hu Zhao, Li Quan Lee, Xiang Chu, Ying Li & Hong Li

Department of Civil Engineering, Monash University, Melbourne, Victoria, Australia

Ziying Sun & Jin Zhou

Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, Singapore, Singapore

Chenchen Li, Dan Wu, Li Quan Lee, Dan Lu & Yan Zhou

Nanyang Environment and Water Research Institute (NEWRI), Nanyang Technological University, Singapore, Singapore

Yunbo Lv

School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Shenzhen, People’s Republic of China

Wenguang Tu & Zhigang Zou

Energy Research Institute, Nanyang Technological University, Singapore, Singapore

Ovi Lian Ding

School of Civil and Environmental Engineering, Nanyang Technological University, Singapore, Singapore

Yan Zhou

CINTRA CNRS/NTU/THALES, IRL 3288, Singapore, Singapore

Hong Li

School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, Singapore

Hong Li

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H.Z. and H.L. designed the experiments. H.Z. performed electrode fabrication and electrochemical characterizations. D.W. carried out the biosynthesis experiments. C.L., H.Z. and L.Q.L. conducted the product identification and quantification. H.Z. performed material characterizations. Y. Lv helped with the GPC and high-performance liquid chromatograph analysis. X.C. helped with the schematic diagram drawing. Z.S. took the LCA and TEA analysis. H.Z. wrote the paper. H.Z., D.L., Z.S., Y. Li, O.L.D., W.T., Z.Z., J.Z., Y.Z. and H.L. discussed the results and commented on the paper.

Correspondence to Yan Zhou or Hong Li.

H.Z., L.Q.L. and H.L. are inventors on a PCT application related to this work, filed by International Bureau at the WIPO (application number PCT/SG2022/050112). The other authors declare no competing interests.

Nature Water thanks Rong He, Damien Voiry and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Methods, Notes 1–7, Figs. 1–63 and Tables 1–6.

Solar-driven MEA reactor for scalable hybrid sludge reforming and hydrogen generation demonstration.

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Zhao, H., Sun, Z., Li, C. et al. Solar-driven sewage sludge electroreforming coupled with biological funnelling to cogenerate green food and hydrogen. Nat Water (2024). https://doi.org/10.1038/s44221-024-00329-z

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Received: 08 January 2024

Accepted: 27 September 2024

Published: 01 November 2024

DOI: https://doi.org/10.1038/s44221-024-00329-z

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