Exogenous indirect photoinactivation of bacterial pathogens and indicators in water with natural and synthetic photosensitizers in simulated sunlight with reduced
            <scp>UVB</scp>

Maraccini, Peter A.; Wenk, Jannis; Boehm, Alexandria B.

doi:10.1111/jam.13183

Cited by 20 publications

(26 citation statements)

References 44 publications

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“…Campylobacter jejuni is more vulnerable to sunlight damage than Salmonella enterica, which is more vulnerable than E. coli (Sinton et al, 2007). Enterococci and E. coli are equally as vulnerable to sunlight in clear water (Kadir and Nelson, 2014;Maraccini et al, 2016;Silverman et al, 2016), but enterococci were inactivated more rapidly than E. coli in a WSP in Ouagadougou, Burkina Faso (Maiga et al, 2009b), perhaps due to their greater vulnerability to sunlight in the presence of external photosensitizer molecules that may be present in WSPs with high concentrations of organic suspended solids (Kadir and Nelson, 2014). Bacteria can repair sunlight damage in the dark (Oguma et al, 2001), while viruses cannot (however, a few viruses may be able to repair sunlight-induced damage after initiating an infection, by utilizing their host cell's DNA repair machinery (Weitzman et al, 2004).…”

Section: Sunlight and Water Claritymentioning

confidence: 99%

Waste Stabilization Ponds

Verbyla¹,

Sperling²,

Maïga³

2019

Water and Sanitation for the 21st Century: Health and Microbiological Aspects of Excreta and Wastewater Management (Global Wate

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The designations employed and the presentation of material throughout this publication do not imply the expression of any opinion whatsoever on the part of UNESCO concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. The ideas and opinions expressed in this publication are those of the authors; they are not necessarily those of UNESCO and do not commit the Organization.

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Section: Sunlight and Water Claritymentioning

confidence: 99%

Waste Stabilization Ponds

Verbyla¹,

Sperling²,

Maïga³

2019

Water and Sanitation for the 21st Century: Health and Microbiological Aspects of Excreta and Wastewater Management (Global Wate

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“…faecalis, E. coli K12, E. coli O157:H7, Salmonella enterica serovarTyphimurium LT2, Staphylococcus aureus, and Streptococcus bovis) to exogenous inactivation by synthetic and natural sensitizers conrmed that the Grampositive bacteria were more susceptible to exogenous inactivation than the Gram-negative bacteria. 155,159 When UVB wavelengths were present, all of the Gram-positive bacteria experienced faster inactivation in the presence of at least one synthetic sensitizer. However, the natural sensitizers only increased the inactivation rate when the UVB wavelengths were not present.…”

Section: Exogenous Mechanismsmentioning

confidence: 99%

Sunlight-mediated inactivation of health-relevant microorganisms in water: a review of mechanisms and modeling approaches

Nelson

Boehm

Davies‐Colley

et al. 2018

Environ. Sci.: Processes Impacts

197

221

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Health-relevant microorganisms present in natural surface waters and engineered treatment systems that are exposed to sunlight can be inactivated by a complex set of interacting mechanisms. The net impact of sunlight depends on the solar spectral irradiance, the susceptibility of the specific microorganism to each mechanism, and the water quality; inactivation rates can vary by orders of magnitude depending on the organism and environmental conditions. Natural organic matter (NOM) has a large influence, as it can attenuate radiation and thus decrease inactivation by endogenous mechanisms. Simultaneously NOM sensitizes the formation of reactive intermediates that can damage microorganisms via exogenous mechanisms. To accurately predict inactivation and design engineered systems that enhance solar inactivation, it is necessary to model these processes, although some details are not yet sufficiently well understood. In this critical review, we summarize the photo-physics, -chemistry, and -biology that underpin sunlight-mediated inactivation, as well as the targets of damage and cellular responses to sunlight exposure. Viruses that are not susceptible to exogenous inactivation are only inactivated if UVB wavelengths (280-320 nm) are present, such as in very clear, open waters or in containers that are transparent to UVB. Bacteria are susceptible to slightly longer wavelengths. Some viruses and bacteria (especially Gram-positive) are susceptible to exogenous inactivation, which can be initiated by visible as well as UV wavelengths. We review approaches to model sunlightmediated inactivation and illustrate how the environmental conditions can dramatically shift the inactivation rate of organisms. The implications of this mechanistic understanding of solar inactivation are discussed for a range of applications, including recreational water quality, natural treatment systems, solar disinfection of drinking water (SODIS), and enhanced inactivation via the use of sensitizers and photocatalysts. Finally, priorities for future research are identified that will further our understanding of the key role that sunlight disinfection plays in natural systems and the potential to enhance this process in engineered systems. Environmental signicanceThe manuscript provides a comprehensive synthesis of the current understanding of the mechanisms by which sunlight causes damage to microorganisms, ultimately leading to inactivation. This topic is important for understanding the fate and transport of microbiological contaminants in all sunlit surface waters, including fresh and marine ecosystems, as well as engineered treatment systems.

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“…External sensitisers found in water also can damage bacteria via exogenous indirect photoinactivation under UVA radiation, specifically in Gram-positive cells: Enterococci (Gram-positive bacteria) are susceptible to indirect exogenous damage, but E. coli (Gram-negative bacteria) does not show noticeable inactivation [ 85 , 86 ]. Figure 4 sums up the inactivation mechanisms in bacteria.…”

Section: Sodis: Variablesmentioning

confidence: 99%

Solar Water Disinfection to Produce Safe Drinking Water: A Review of Parameters, Enhancements, and Modelling Approaches to Make SODIS Faster and Safer

et al. 2021

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Solar water disinfection (SODIS) is one the cheapest and most suitable treatments to produce safe drinking water at the household level in resource-poor settings. This review introduces the main parameters that influence the SODIS process and how new enhancements and modelling approaches can overcome some of the current drawbacks that limit its widespread adoption. Increasing the container volume can decrease the recontamination risk caused by handling several 2 L bottles. Using container materials other than polyethylene terephthalate (PET) significantly increases the efficiency of inactivation of viruses and protozoa. In addition, an overestimation of the solar exposure time is usually recommended since the process success is often influenced by many factors beyond the control of the SODIS-user. The development of accurate kinetic models is crucial for ensuring the production of safe drinking water. This work attempts to review the relevant knowledge about the impact of the SODIS variables and the techniques used to develop kinetic models described in the literature. In addition to the type and concentration of pathogens in the untreated water, an ideal kinetic model should consider all critical factors affecting the efficiency of the process, such as intensity, spectral distribution of the solar radiation, container-wall transmission spectra, ageing of the SODIS reactor material, and chemical composition of the water, since the substances in the water can play a critical role as radiation attenuators and/or sensitisers triggering the inactivation process.

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Exogenous indirect photoinactivation of bacterial pathogens and indicators in water with natural and synthetic photosensitizers in simulated sunlight with reduced UVB

Abstract: UVB is the most important range of the sunlight spectrum for bacterial photoinactivation. In aquatic environments where photosensitizers are present and there is high UVB light attenuation, UVA and visible wavelengths can contribute to exogenous indirect photoinactivation.

Cited by 20 publications

References 44 publications

Waste Stabilization Ponds

Waste Stabilization Ponds

Sunlight-mediated inactivation of health-relevant microorganisms in water: a review of mechanisms and modeling approaches

Solar Water Disinfection to Produce Safe Drinking Water: A Review of Parameters, Enhancements, and Modelling Approaches to Make SODIS Faster and Safer

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