Speeding up solar disinfection (SODIS): effects of hydrogen peroxide, temperature, pH, and copper plus ascorbate on the photoinactivation of E. coli

Fisher, Michael B.; Keenan, Christina R.; Nelson, Kara L.; Voelker, Bettina M.

doi:10.2166/wh.2007.005

Cited by 80 publications

(63 citation statements)

References 38 publications

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“…These results suggest that a pH below 4 alone may be sufficient to dramatically reduce E. coli viability in the presence of sunlight. These results are consistent with findings of some other investigators, 21 but are in contrast to investigators who did not observe any changes in killing of E. coli with a solar lamp between pH 4-9. 54 Interestingly, none of the bottles with low pH showed substantial inhibition of E. coli in the dark except for Lime Slurry Dark and Lemon Slurry Dark.…”

Section: Discussionsupporting

confidence: 93%

“…However, our research and that of previous studies using artificial UV sources suggest the possibility of other mechanisms. 21 We performed two experiments comparing effects of adding lime, lemon, and HCl to the SODIS protocol. In a 30-minute exposure, all these preparations strongly inactivated E. coli.…”

Section: Discussionmentioning

confidence: 99%

“…13,14 This form of disinfection is more than 1,000-fold slower than direct damage of UV-C. 15 Several researchers have looked for means to accelerate SODIS, using such compounds as riboflavin, TiO 2 , H 2 O 2 , and copper plus ascorbic acid. [16][17][18][19][20][21] Many of these compounds have photoactivity in the UV-A spectrum, thereby enhancing normally inefficient insults of UV-A against microorganisms.…”

Section: Introductionmentioning

confidence: 99%

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Using Limes and Synthetic Psoralens to Enhance Solar Disinfection of Water (SODIS): A Laboratory Evaluation with Norovirus, Escherichia coli, and MS2

Harding¹,

Schwab²

2012

The American Society of Tropical Medicine and Hygiene

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We investigated the use of psoralens and limes to enhance solar disinfection of water (SODIS) using an UV lamp and natural sunlight experiments. SODIS conditions were replicated using sunlight, 2 L polyethylene terephthalate (PET) bottles, and tap water with Escherichia coli, MS2 bacteriophage, and murine norovirus (MNV). Psoralens and lime acidity both interact synergistically with UV radiation to accelerate inactivation of microbes. Escherichia coli was ablated > 6.1 logs by SODIS + Lime Slurry and 5.6 logs by SODIS + Lime Juice in 30-minute solar exposures, compared with a 1.5 log reduction with SODIS alone (N = 3; P < 0.001). MS2 was inactivated > 3.9 logs by SODIS + Lime Slurry, 1.9 logs by SODIS + Lime Juice, and 1.4 logs by SODIS in 2.5-hour solar exposures (N = 3; P < 0.05). MNV was resistant to SODIS, with < 2 log reductions after 6 hours. Efficacy of SODIS against human norovirus should be investigated further.

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Section: Discussionsupporting

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Using Limes and Synthetic Psoralens to Enhance Solar Disinfection of Water (SODIS): A Laboratory Evaluation with Norovirus, Escherichia coli, and MS2

Harding¹,

Schwab²

2012

The American Society of Tropical Medicine and Hygiene

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“…222,248-252 The observed benets of H 2 O 2 addition can been attributed to its participation in endogenous or exogenous photo-Fenton processes involving Fe(II) or Fe(III) associated with biomolecules present in the target microbial agents, 222,248,253,254 or naturally-occurring Fe(III) associated with Fe-(hydr)oxide complexes, Fe-organic ligand complexes (formed through interactions with acidic groups in NOM), and/or solid Fe oxides present in the water to be treated. Photo-Fenton processes are in each case expected to lead to production of such oxidants as cOH or Fe(IV), depending on solution pH.…”

mentioning

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

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209

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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“…coli photoinactivation rates were likewise shown to decrease in the presence of hydrogen peroxide scavengers (9,10,14,16) and increase in the presence of added H 2 O 2 (17)(18)(19)(20). Finally, researchers found that E. coli exposed to sunlight in seawater recovered poorly on glucose medium unless supplemented with pyruvate, suggesting a light-induced sensitivity to peroxides (21).…”

mentioning

confidence: 99%

Inactivation of Escherichia coli by Polychromatic Simulated Sunlight: Evidence for and Implications of a Fenton Mechanism Involving Iron, Hydrogen Peroxide, and Superoxide

Fisher

Nelson

2014

Appl Environ Microbiol

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Sunlight inactivation of Escherichia coli has previously been shown to accelerate in the presence of oxygen, exogenously added hydrogen peroxide, and bioavailable forms of exogenously added iron. In this study, mutants unable to effectively scavenge hydrogen peroxide or superoxide were found to be more sensitive to polychromatic simulated sunlight (without UVB wavelengths) than wild-type cells, while wild-type cells grown under low-iron conditions were less sensitive than cells grown in the presence of abundant iron. Furthermore, prior exposure to simulated sunlight was found to sensitize cells to subsequent hydrogen peroxide exposure in the dark, but this effect was attenuated for cells grown with low iron. Mutants deficient in recombination DNA repair were sensitized to simulated sunlight (without UVB wavelengths), but growth in the presence of iron chelators reduced the degree of sensitization conferred by this mutation. These findings support the hypothesis that hydrogen peroxide, superoxide, and intracellular iron all participate in the photoinactivation of E. coli and further suggest that the inactivation rate of enteric bacteria in the environment may be strongly dependent on iron availability and growth conditions.

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Speeding up solar disinfection (SODIS): effects of hydrogen peroxide, temperature, pH, and copper plus ascorbate on the photoinactivation of E. coli

Cited by 80 publications

References 38 publications

Using Limes and Synthetic Psoralens to Enhance Solar Disinfection of Water (SODIS): A Laboratory Evaluation with Norovirus, Escherichia coli, and MS2

Using Limes and Synthetic Psoralens to Enhance Solar Disinfection of Water (SODIS): A Laboratory Evaluation with Norovirus, Escherichia coli, and MS2

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

Inactivation of Escherichia coli by Polychromatic Simulated Sunlight: Evidence for and Implications of a Fenton Mechanism Involving Iron, Hydrogen Peroxide, and Superoxide

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