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Published (Version of record)CC BY V4.0, Open Access
Published (Version of record)CC BY V4.0, Open
Journal article
Pathogen performance testing of a natural swimming pool using a cocktail of microbiological surrogates and QMRA-derived management goals
Journal of water and health, Vol.19(4), pp.629-641
08/06/2021
PMID: 34371499
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Abstract
Abstract In recent decades, natural swimming pools (NSPs) have gained popularity in Europe, especially in Germany and Austria. NSPs differ from swimming pools in that they utilize biological treatment processes based on wetland processes with no disinfection residual. However, data are missing on the specific log-reduction performance of NSPs to address enteric virus, bacteria, and parasitic protozoa removal considered necessary to meet the North American risk-based benchmark (<35 illnesses per 1,000 swimming events) set by the USEPA for voluntary swimming. In this study, we examined Canada's first NSP at Borden Park, Edmonton, Canada, to address the following three questions: (1) Given normal faecal shedding rates by bathers, what is the total log reduction (TLR) theoretically needed to meet the EPA benchmark? (2) what is the in-situ performance of the NSP based on spiking suitable microbial surrogates (MS2 coliphage, Enterococcus faecalis, and Saccharomyces cerevisiae [Baker's yeast])? and (3) how much time is required to reach acceptable bather risk levels under different representative volume-turnover rates? A reverse-quantitative microbial risk assessment (QMRA) revealed that of the four reference pathogens selected (Norovirus, Campylobacter, Cryptosporidium, and Giardia), only Norovirus was estimated to exceed the risk benchmark at the 50th, 75th, and 95th percentiles, while Campylobacter was the only other reference pathogen to exceed at the 95th percentile. Log-reduction values (LRVs) were similar to previous reports for bacterial indicators, and novel LRVs were estimated for the other two surrogates. A key finding was that more than 24 h treatment time would be necessary to provide acceptable bather protection following heavy bather use (378 bathers/day for main pool and 26 bathers/day for children's pool), due to the mixing dynamics of the treated water diluting out possible residual pool faecal contamination. The theoretical maximum number of people in the pool per day to be below USEPA's 35 gastro cases in 1,000 swimming events was 113, 47, and 8, at the 50th, 75th, and 95th percentiles. Further, the use of ultra-violet disinfection to the pool return flow had little effect on reducing the treatment time required.
Details
- Title
- Pathogen performance testing of a natural swimming pool using a cocktail of microbiological surrogates and QMRA-derived management goals
- Creators
- David C. Shoults - Centre for Water Resources Studies, Dalhousie University, Halifax, Nova Scotia B3H 4R2, CanadaQiaozhi Li - School of Public Health, University of Alberta, Edmonton, Alberta T6G 2G7, CanadaSusan Petterson - Water & Health Pty Ltd, North Sydney, NSW 2060, Australia, School of Medicine, Griffith University, Gold Coast, QLD 4222, AustraliaSydney P Rudko - School of Public Health, University of Alberta, Edmonton, Alberta T6G 2G7, CanadaLena Dlusskaya - School of Public Health, University of Alberta, Edmonton, Alberta T6G 2G7, CanadaMats Leifels - Singapore Centre of Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551, CanadaCandis Scott - School of Public Health, University of Alberta, Edmonton, Alberta T6G 2G7, CanadaCyndi Schlosser - Borden Park, City of Edmonton, Edmonton, Alberta T5B 4W8, CanadaNicholas Ashbolt (Corresponding Author) - Southern Cross University
- Publication Details
- Journal of water and health, Vol.19(4), pp.629-641
- Identifiers
- 991012955600402368
- Academic Unit
- Faculty of Science and Engineering
- Language
- English
- Resource Type
- Journal article