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Water 2017, 9(12), 963; https://doi.org/10.3390/w9120963

UV Disinfection of Hand-Rinse Greywater and Performance Testing Using Indigenous Staphylococcus spp.

School of Public Health, University of Alberta, Edmonton, AB T6G 2R3, Canada
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Received: 1 November 2017 / Revised: 4 December 2017 / Accepted: 8 December 2017 / Published: 11 December 2017
(This article belongs to the Special Issue Development of Alternative Water Sources in the Urban Sector)
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Abstract

Greywater reuse is a feasible solution for decreasing raw water extraction in urban and rural settings. However, pathogen-specific performance guidelines and regulations have only recently been recommended; practical means to assess performance are missing. Here we examine the efficacy of Staphylococcus spp. as an endogenous surrogate for greywater pathogen reduction performance testing, by evaluating UV-C irradiation of hand-rinse greywater, and the variability in UV resistance between different wild Staphylococcus species. Hand-rinse greywater samples were collected from five participants, and a collimated UV-C beam (256 nm) was used to assess log10 reductions. Assays of colony-forming units on tryptic soy agar (TSA) were compared to mannitol salt agar (MSA) using LysostaphinTM to confirm Staphylococcus spp. After irradiating raw hand-rinse samples to a dose of 220 mJ·cm−2, log10 reductions of Staphylococcus spp. were similar (2.1 and 2.2, respectively, p = 0.112). The similarity of the reduction based on TSA and Staphylococcus-specific culture assays following UV irradiation and the dominating presence of Staphylococcus spp. suggests that Staphylococcus spp. could be used as an endogenous performance surrogate group for greywater treatment testing. Suspended wild Staphylococcus isolates were irradiated with 256 nm UV-C to compare the variability of different Staphylococcus species. Staphylococcus isolates exhibited significant variance in log10 reduction values when exposed to 11 mJ·cm−2 of UV-C. Staphylococcus hominis subsp. hominis exhibited surprising resistance to UV-C, with only a 1.6-log10 reduction when exposed to 11 mJ·cm−2 of UV-C (most other isolates exhibited > 5-log10 reduction). The efficacy of UV-C was also significantly reduced when the sunscreen oxybenzone was present at a possible endogenous greywater concentration. View Full-Text
Keywords: greywater; water reuse; greywater reuse; Staphylococcus aureus; Staphylococcus spp.; alternative water sources; onsite treatment and reuse; sustainable urban water use greywater; water reuse; greywater reuse; Staphylococcus aureus; Staphylococcus spp.; alternative water sources; onsite treatment and reuse; sustainable urban water use
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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Shoults, D.C.; Ashbolt, N.J. UV Disinfection of Hand-Rinse Greywater and Performance Testing Using Indigenous Staphylococcus spp.. Water 2017, 9, 963.

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