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Technology assessment of solar disinfection for drinking water treatment

Abstract

Poor access to safe drinking water is a major sustainability issue for a third of the world’s population, especially for those living in rural areas. Solar disinfection could be the choice of technology considering the abundant sunlight exposure in infrastructure-limited regions. However, despite recent technological advances, it remains unclear which solar disinfection option is more broadly applicable and reliable, enabling the most efficient use of solar radiation. Here we examine the potential of five most typical solar-based, point-of-use water disinfection technologies, including semiconductor photocatalysis to produce hydroxyl radical, dye photosensitization to produce singlet oxygen, ultraviolet irradiation using light-emitting diodes powered by a photovoltaic panel, distillation using a solar still and solar pasteurization by raising the bulk water temperature to 75 °C. The sensitivity analysis allows us to assess how pathogen type, materials property, geographical variation in solar intensity and water-quality parameters interactively affect the effectiveness of these technologies under different scenarios. Revealed critical challenges point to the large gap between idealized materials properties and state of the art, the risk of focusing on select pathogens that show maximum inactivation effectiveness and the failure to consider uncertainties in water quality and geographical variations. Our analysis also suggests future pathways towards effective solar disinfection technology development and real-world implementation.

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Fig. 1: Solar-based POU technologies examined in this study.
Fig. 2: Global mapping of disinfection capacity by each solar-based POU technology in various cases.
Fig. 3: Results of sensitivity analyses and Monte Carlo simulations.
Fig. 4: Range of disinfection capacity of solar-based POU technologies by various types of pathogens, latitude and month.

Data availability

Datasets used in this study were accessed from publicly available sources. Long-term annual average surface solar radiation data (global horizontal irradiance (GHI), kWh m–2 d−1) from 45° S to 60° N at 30 arcsec resolution was sourced from the Global Solar Atlas 2.064. For the sensitivity analyses and Monte Carlo simulations, the monthly sunlight intensity was obtained from the NASA Langley Research Center Atmospheric Science Data Center Surface Meteorological and Solar Energy (SSE)70,71,72, which provides the surface sunlight intensity across the globe at 1° latitude by 1° longitude resolution, while the monthly surface temperature was obtained from the Berkeley Earth website (http://berkeleyearth.org/). Data pertaining to national, rural and urban access to WASH services, and the rate of change in access, were sourced from the World Health Organization–United Nations Children’s Fund (WHO–UNICEF) Joint Monitoring Program3, and data reporting the burden of disease/specific diarrhoeal mortality rates for insufficient WASH improvements access was acquired from the WHO Global Health Observatory data repository4. Country economic parameters, including poverty metrics, GDP per capita and other measures of wealth were sourced from the World Bank World Development Indicators73, while information on country-specific WASH financing structures and investments were acquired through the United Nations Water Global Analysis and Assessment of Sanitation and Drinking Water7,33.

Code availability

The R software, GraphPad Prism X9 software and the freely available R packages were used for all data exploration and statistical analyses. The codes that support the findings of this study are available from the corresponding author upon reasonable request.

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Acknowledgements

This study was funded by the National Science Foundation Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment (EEC-1449500).

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J.-H.K. and P.J.J.A. conceived the idea and supervised the work. I.J. designed the analysis, collected the data, implemented overall analysis, interpreted the data and wrote the manuscript and Supplementary Materials. E.C.R. collected the data and contributed to data interpretation and writing Supplementary Materials. All authors contributed to the reviewing and the editing of the manuscript.

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Correspondence to Jae-Hong Kim.

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Nature Sustainability thanks Kevin McGuigan and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Notes 1–20, Figs. 1–15 and Tables 1–14.

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Jeon, I., Ryberg, E.C., Alvarez, P.J.J. et al. Technology assessment of solar disinfection for drinking water treatment. Nat Sustain 5, 801–808 (2022). https://doi.org/10.1038/s41893-022-00915-7

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