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.
This is a preview of subscription content, access via your institution
Subscribe to Nature+
Get immediate online access to the entire Nature family of 50+ journals
Subscribe to Journal
Get full journal access for 1 year
only $9.92 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Get time limited or full article access on ReadCube.
All prices are NET prices.
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.
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.
Sustainable Development Goal 6: Synthesis Report 2018 on Water and Sanitation (United Nations, 2018).
The Millennium Development Goals Report 2015 (United Nations, 2015).
Progress on Household Drinking Water, Sanitation and Hygiene 2000–2017: Special Focus on Inequalities (UNICEF and WHO, 2019).
Global Health Observatory Data Repository (WHO, accessed 9 June 2022); https://www.who.int
Montgomery, M. A. & Elimelech, M. Water and sanitation in developing countries: including health in the equation. Environ. Sci. Technol. 41, 17–24 (2007).
Combating Waterborne Disease at the Houshold Level (WHO, 2007).
Results of Round II of the WHO International Scheme to Evaluate Household Water Treatment Technologies (WHO, 2019).
Chu, C., Ryberg, E. C., Loeb, S. K., Suh, M.-J. & Kim, J.-H. Water disinfection in rural areas demands unconventional solar technologies. Acc. Chem. Res. 52, 1187–1195 (2019).
McGuigan, K. G. et al. Solar water disinfection (SODIS): a review from bench-top to roof-top. J. Hazard. Mater. 235, 29–46 (2012).
Fisher, M. B., Keenan, C. R., Nelson, K. L. & Voelker, B. M. Speeding up solar disinfection (SODIS): effects of hydrogen peroxide, temperature, pH, and copper plus ascorbate on the photoinactivation of E. coli. J. Water Health 6, 35–51 (2008).
Shannon, M. A. et al. In Nanoscience and Technology: A Collection of Reviews from Nature Journals (ed. Rodgers, P.) 337–346 (World Scientific, 2010).
Loeb, S., Li, C. & Kim, J.-H. Solar photothermal disinfection using broadband-light absorbing gold nanoparticles and carbon black. Environ. Sci. Technol. 52, 205–213 (2018).
Loeb, S. K. et al. Nanoparticle enhanced interfacial solar photothermal water disinfection demonstrated in 3-D printed flow-through reactors. Environ. Sci. Technol. 53, 7621–7631 (2019).
Wigginton, K. R. & Kohn, T. Virus disinfection mechanisms: the role of virus composition, structure, and function. Curr. Opin. Virol. 2, 84–89 (2012).
Fraise, A. P., Lambert, P. A. & Maillard, J.-Y. Russell, Hugo & Ayliffe’s Principles and Practice of Disinfection, Preservation and Sterilization (Wiley & Sons, 2008).
McDonnell, G. E. Antisepsis, Disinfection, and Sterilization: Types, Action, and Resistance (Wiley & Sons, 2020).
Burch, J. D. & Thomas, K. E. Water disinfection for developing countries and potential for solar thermal pasteurization. Sol. Energy 64, 87–97 (1998).
Sampathkumar, K., Arjunan, T., Pitchandi, P. & Senthilkumar, P. Active solar distillation—a detailed review. Renew. Sustain. Energy Rev. 14, 1503–1526 (2010).
Wang, Z. et al. Pathways and challenges for efficient solar-thermal desalination. Sci. Adv. 5.7, aax0763 (2019).
Pang, Y. et al. Solar-thermal water evaporation: a review. ACS Energy Lett. 5, 437–456 (2020).
Results of Round I of the WHO International Scheme to Evaluate Household Water Treatment Technologies (WHO, 2016).
Velmurugan, V., Gopalakrishnan, M., Raghu, R. & Srithar, K. Single basin solar still with fin for enhancing productivity. Energy Convers. Manage. 49, 2602–2608 (2008).
Badran, O. O. & Abu-Khader, M. M. Evaluating thermal performance of a single slope solar still. Heat Mass Transf. 43, 985–995 (2007).
Luzi, S., Tobler, M., Suter, F. & Meierhofer, R. SODIS Manual: Guidance on Solar Water Disinfection (Eawag, 2016).
Loeb, S. K. et al. The technology horizon for photocatalytic water treatment: sunrise or sunset? Environ. Sci. Technol. 53, 2937–2947 (2019).
Hirayama, H., Tsukada, Y., Maeda, T. & Kamata, N. Marked enhancement in the efficiency of deep-ultraviolet AlGaN light-emitting diodes by using a multiquantum-barrier electron blocking layer. Appl. Phys. Express 3, 031002 (2010).
Shur, M. S. & Gaska, R. Deep-ultraviolet light-emitting diodes. IEEE Trans. Electron Devices 57, 12–25 (2009).
Khan, A., Balakrishnan, K. & Katona, T. Ultraviolet light-emitting diodes based on group three nitrides. Nat. Photonics 2, 77–84 (2008).
Zhang, X. et al. Global sensitivity analysis of environmental, water quality, photoreactivity, and engineering design parameters in sunlight inactivation of viruses. Environ. Sci. Technol. 54, 8401–8410 (2020).
Haag, W. R. & Yao, C. D. Rate constants for reaction of hydroxyl radicals with several drinking water contaminants. Environ. Sci. Technol. 26, 1005–1013 (1992).
Brown, J. & Clasen, T. High adherence is necessary to realize health gains from water quality interventions. PLoS ONE 7, e36735 (2012).
Trimmer, J. T. et al. Re-envisioning sanitation as a human-derived resource system. Environ. Sci. Technol. 54, 10446–10459 (2020).
UN-Water Global Analysis and Assessment of Sanitation and Drinking-Water (GLAAS) 2019 Report: National Systems to Support Drinking-Water, Sanitation and Hygiene: Global Status Report 2019 (WHO, 2019).
The United Nations World Water Development Report 2019: Leaving No One Behind (United Nations Educational, Scientific and Cultural Organization, 2019).
Enger, K. S., Nelson, K. L., Rose, J. B. & Eisenberg, J. N. The joint effects of efficacy and compliance: a study of household water treatment effectiveness against childhood diarrhea. Water Res. 47, 1181–1190 (2013).
Hijnen, W., Beerendonk, E. & Medema, G. J. Inactivation credit of UV radiation for viruses, bacteria and protozoan (oo)cysts in water: a review. Water Res. 40, 3–22 (2006).
Evaluating Household Water Treatment Options: Health-Based Targets and Microbiological Performance Specifications (WHO, 2011).
Kohn, T. & Nelson, K. L. Sunlight-mediated inactivation of MS2 coliphage via exogenous singlet oxygen produced by sensitizers in natural waters. Environ. Sci. Technol. 41, 192–197 (2007).
Guidelines for Drinking-Water Quality 4th edn (WHO, 2011).
National Primary Drinking Water Regulations: Long Term 2 Enhanced Surface Water Treatment Rule; Final Rule (US EPA, 2006).
Loeb, S., Hofmann, R. & Kim, J.-H. Beyond the pipeline: assessing the efficiency limits of advanced technologies for solar water disinfection. Environ. Sci. Technol. Lett. 3, 73–80 (2016).
Liu, B., Zhao, X., Terashima, C., Fujishima, A. & Nakata, K. Thermodynamic and kinetic analysis of heterogeneous photocatalysis for semiconductor systems. Phys. Chem. Chem. Phys. 16, 8751–8760 (2014).
Malato, S., Fernández-Ibáñez, P., Maldonado, M. I., Blanco, J. & Gernjak, W. Decontamination and disinfection of water by solar photocatalysis: recent overview and trends. Catal. Today 147, 1–59 (2009).
Cho, M., Chung, H., Choi, W. & Yoon, J. Linear correlation between inactivation of E. coli and OH radical concentration in TiO2 photocatalytic disinfection. Water Res. 38, 1069–1077 (2004).
Cho, M., Cates, E. L. & Kim, J.-H. Inactivation and surface interactions of MS-2 bacteriophage in a TiO2 photoelectrocatalytic reactor. Water Res. 45, 2104–2110 (2011).
Park, G. W. et al. Fluorinated TiO2 as an ambient light-activated virucidal surface coating material for the control of human norovirus. J. Photochem. Photobiol. B 140, 315–320 (2014).
Nelson, K. L. et al. Sunlight-mediated inactivation of health-relevant microorganisms in water: a review of mechanisms and modeling approaches. Environ. Sci. Process. Impacts 20, 1089–1122 (2018).
DeRosa, M. C. & Crutchley, R. J. Photosensitized singlet oxygen and its applications. Coord. Chem. Rev. 233–234, 351–371 (2002).
Dobrowsky, P. et al. Efficiency of microfiltration systems for the removal of bacterial and viral contaminants from surface and rainwater. Water Air Soil Pollut. 226, 33 (2015).
Dobrowsky, P., Carstens, M., De Villiers, J., Cloete, T. & Khan, W. Efficiency of a closed-coupled solar pasteurization system in treating roof harvested rainwater. Sci. Total Environ. 536, 206–214 (2015).
Abraham, J., Plourde, B. & Minkowycz, W. Continuous flow solar thermal pasteurization of drinking water: methods, devices, microbiology, and analysis. Renew. Energy 81, 795–803 (2015).
Spinks, A. T., Dunstan, R., Harrison, T., Coombes, P. & Kuczera, G. Thermal inactivation of water-borne pathogenic and indicator bacteria at sub-boiling temperatures. Water Res. 40, 1326–1332 (2006).
Sanciolo, P. et al. Pasteurisation for Production of Class A Recycled Water: A Report of a Study Funded by the Australian Water Recycling Centre of Excellence Report No. 1922202665 (Australian Water Recycling Centre of Excellence, 2015).
Parry, J. & Mortimer, P. The heat sensitivity of hepatitis A virus determined by a simple tissue culture method. J. Med. Virol. 14, 277–283 (1984).
Hewitt, J., Rivera‐Aban, M. & Greening, G. Evaluation of murine norovirus as a surrogate for human norovirus and hepatitis A virus in heat inactivation studies. J. Appl. Microbiol. 107, 65–71 (2009).
Maheshwari, G., Jannat, R., McCormick, L. & Hsu, D. Thermal inactivation of adenovirus type 5. J. Virol. Methods 118, 141–146 (2004).
Strazynski, M., Krämer, J. & Becker, B. Thermal inactivation of poliovirus type 1 in water, milk and yoghurt. Int. J. Food Microbiol. 74, 73–78 (2002).
Fujino, T. et al. The effect of heating against Cryptosporidium oocysts. J. Vet. Med. Sci. 64, 199–200 (2002).
Fayer, R. Effect of high temperature on infectivity of Cryptosporidium parvum oocysts in water. Appl. Environ. Microbiol. 60, 2732–2735 (1994).
Harp, J. A., Fayer, R., Pesch, B. A. & Jackson, G. J. Effect of pasteurization on infectivity of Cryptosporidium parvum oocysts in water and milk. Appl. Environ. Microbiol. 62, 2866–2868 (1996).
Jarroll, E. L., Hoff, J. C. & Meyer, E. A. in Giardia and Giardiasis (eds Erlandsen, S. L. & Meyer, E. A.) 311–328 (Springer, 1984).
Ongerth, J. E., Johnson, R. L., MacDonald, S. C., Frost, F. & Stibbs, H. H. Back-country water treatment to prevent giardiasis. Am. J. Public Health 79, 1633–1637 (1989).
Schaefer, F. W., Rice, E. W. & Hoff, J. C. Factors promoting in vitro excystation of Giardia muris cysts. Trans. R. Soc. Trop. Med. Hyg. 78, 795–800 (1984).
Global Solar Atlas 2.0 (World Bank Group, 2020); https://globalsolaratlas.info/
R Core Team. R: A language and environment for statistical computing (R Foundation for Statistical Computing, 2021).
Campolongo, F., Cariboni, J. & Saltelli, A. An effective screening design for sensitivity analysis of large models. Environ. Model. Softw. 22, 1509–1518 (2007).
Saltelli, A. Sensitivity analysis for importance assessment. Risk Anal. 22, 579–590 (2002).
Sobol, I. M. Sensitivity analysis for non-linear mathematical models. Math. Modell. Comput. Exp. 1, 407–414 (1993).
Saltelli, A., Tarantola, S., Campolongo, F. & Ratto, M. Sensitivity Analysis in Practice: A Guide to Assessing Scientific Models Vol. 1 (Wiley Online Library, 2004).
Zhang, T. et al. A global perspective on renewable energy resources: NASA’s prediction of worldwide energy resources (power) project. In Proc. ISES World Congress 2007 Vol. 1–Vol. 5 (eds Goswami, D. Y. & Zhao, Y.) 2636–2640 (Springer, 2009).
Stackhouse, P. Jr. et al. Surface Meteorology and Solar Energy (SSE) Release 6.0 Methodology version 3.2.0 (NASA, 2016).
Stackhouse, P. Jr. et al. Supporting energy-related societal applications using NASA’s satellite and modeling data. In Proc. 2006 IEEE International Symposium on Geoscience and Remote Sensing (ed. Tsang, L.) 425–428 (IEEE, 2006).
World Development Indicators (World Bank, accessed 9 June 2022); https://datacatalog.worldbank.org/dataset/world-development-indicators
Haitz, R. H., Craford, M. G. & Weissman, R. H. In Handbook of optics Vol. 2 (ed. Bass, M.) 121–129 (Optical Society of America, 1995).
García-Gil, Á., Abeledo-Lameiro, M. J., Gómez-Couso, H. & Marugán, J. Kinetic modeling of the synergistic thermal and spectral actions on the inactivation of Cryptosporidium parvum in water by sunlight. Water Res. 185, 116226 (2020).
This study was funded by the National Science Foundation Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment (EEC-1449500).
The authors declare no competing interests.
Peer review information
Nature Sustainability thanks Kevin McGuigan and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
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
Nature Sustainability (2022)