Journal article
Decreased efficacy of UV inactivation of Staphylococcus aureus after multiple exposure and growth cycles
International journal of hygiene and environmental health, Vol.222(1), pp.111-116
01/2019
PMID: 30177424
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Abstract
UV disinfection is a relatively simple and cost-efficient disinfection method, especially for in-home greywater treatment. In this study, a bench scale experiment was performed using a LED collimated UV-C beam with a peak wavelength of 256 nm to determine if potentially pathogenic bacteria such as Staphylococcus aureus may become enriched in a semi-recirculating greywater system with UV as the sole disinfection step. A statistically significant (P < 0.001) decreasing trend in UV-C efficacy was observed between the 1st and 6th UV exposure-growth cycles of S. aureus (ATCC 25923), resulting in a 1.5 decrease in log(10) removal (P < 0.00000) by the 5th iteration. An eleven-point dose-response curve of the 7th iteration of S. aureus was estimated and compared to the dose-response curve of the original strain; due to a longer apparent shoulder period and a decay constant of lesser degree, the dose required for a 4-log reduction of the enriched S. aureus was estimated to be similar to 1.9 times greater (22.0 mJ.cm(-2) versus 11.8 mJ.cm(-2)). However, experimental results with S. epidermidis (ATCC 12228) and two wild strains, S. aureus and S. warneri, exhibited no trend of increased resistance. UV doses exceeding 20 mJ.cm(-2) are generally sufficient in achieving a 4-log reduction of bacteria in drinking water systems; however, the results exhibited in this study suggest that when recirculation is involved, there may be a need for UV doses exceeding what is necessary for a 4-log reduction to suppress the enrichment of strains which could pose a public health risk.
Details
- Title
- Decreased efficacy of UV inactivation of Staphylococcus aureus after multiple exposure and growth cycles
- Creators
- David C. Shoults - University of AlbertaNicholas J. Ashbolt - University of Alberta
- Publication Details
- International journal of hygiene and environmental health, Vol.222(1), pp.111-116
- Publisher
- Elsevier
- Number of pages
- 6
- Grant note
- Canada Foundation for Innovation; CGIAR Alberta Innovates
- Identifiers
- 991013097816102368
- Copyright
- © 2018 Elsevier GmbH. All rights reserved.
- Academic Unit
- Faculty of Science and Engineering
- Language
- English
- Resource Type
- Journal article