Greywater reuse - Assessment of the health risk induced by Legionella pneumophila

Blanky, Marina; Sharaby, Yehonatan; Rodríguez-Martínez, Sara; Halpern, Malka; Friedler, Eran

doi:10.1016/j.watres.2017.08.068

Cited by 37 publications

(24 citation statements)

References 45 publications

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“…Instead, prior work has largely focused on reclaimed water use, greywater reuse, and/or roof-harvested rainwater use. 31,45,46 Additionally, Hamilton et al 32 worked backwards from target risk values to derive critical concentrations informing monitoring efforts for L. pneumophila exposures associated with indoor use of potable water. Thus, the current QMRA is novel in its reliance on site-specific empirical measurements of Legionella spp.…”

Section: Discussionmentioning

confidence: 99%

“…from the present study are generally comparable. Blanky et al 45 estimated annual probabilities of subclinical L. pneumophila infection between 10 −8 and 10 −5 for garden irrigation with greywater and between 10 −6 and 10 −4 for toilet flushing with greywater. Meanwhile, Hamilton et al 31 estimated annual probabilities of subclinical L. pneumophila infection between approximately 10 −6 and 10 −2 for a number of exposure scenarios involving roof-harvested rainwater.…”

Section: Discussionmentioning

confidence: 99%

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Flushing of stagnant premise water systems after the COVID-19 shutdown can reduce infection risk by Legionella and Mycobacterium spp

Hozalski

LaPara

Zhao

et al. 2020

Preprint

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The unprecedented widespread closing of buildings due to the COVID-19 pandemic has allowed water to stagnate in premise plumbing systems, creating conditions that may facilitate the growth of opportunistic pathogens. In this study, we flushed and collected samples from showers in buildings that had been unoccupied for approximately two months and quantified Legionella pneumophila using a commercial cultivation-based assay. In addition, all bacteria, Legionella spp., L. pneumophila, L. pneumophila serogroup 1, non-tuberculous mycobacteria (NTM), and Mycobacterium avium complex (MAC) were analyzed using quantitative PCR (qPCR). Despite low or negligible total chlorine in the stagnant pre-flush water samples, L. pneumophila were not detected by either method; Legionella spp., NTM, and MAC, however, were widespread. Using quantitative microbial risk assessment (QMRA), estimated risks of clinical illness from exposure to legionella and MAC via showering were generally low, but the risk of subclinical infection via Legionella spp. could exceed a 10-7 daily risk threshold if just a small fraction (≥0.1 %) of those legionellae detected by qPCR are highly infectious. Flushing cold and hot water lines rapidly restored a total chlorine (as chloramine) residual and decreased all bacterial gene targets to building inlet water levels within 30 min. Following flushing, the chlorine residual rapidly dissipated and bacterial gene targets rebounded, approaching pre-flush concentrations after 6 to 7 days of stagnation. These results suggest that stagnant water in premise plumbing may contain elevated levels of opportunistic pathogens; flushing, however, can rapidly improve water quality and reduce the health risk but the improvement will be short-lived if building disuse persists.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Flushing of stagnant premise water systems after the COVID-19 shutdown can reduce infection risk by Legionella and Mycobacterium spp

Hozalski

LaPara

Zhao

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

“…In the last 20 years, researchers have investigated transmission risks from indoor plumbing and ventilation systems to provide recommendations for building construction and maintenance ( Mckinney et al, 2006 ; Chen et al, 2011 ). Notably a number of studies have investigated the risk of Legionella transmission through indoor plumbing that delivers potable water, greywater or cooling water in multi-unit apartment buildings ( Hamilton et al, 2018 ; Hamilton and Haas, 2016 ; Schoen and Ashbolt, 2011 ; Blanky et al, 2017 ; Sharaby et al, 2019 ). Building drainage systems in multi-unit apartment buildings are commonly served by a main sewer pipe, called a soil-stack ( Fig.…”

Section: Introductionmentioning

confidence: 99%

Quantifying the risk of indoor drainage system in multi-unit apartment building as a transmission route of SARS-CoV-2

Shi

Huang

Quon

et al. 2021

Science of The Total Environment

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The COVID-19 pandemic has had a profound impact on human society. The isolation of SARS-CoV-2 from patients' feces on human cell line raised concerns of possible transmission through human feces including exposure to aerosols generated by toilet flushing and through the indoor drainage system. Currently, routes of transmission, other than the close contact droplet transmission, are still not well understood. A quantitative microbial risk assessment was conducted to estimate the health risks associated with two aerosol exposure scenarios: 1) toilet flushing, and 2) faulty connection of a floor drain with the building's main sewer pipe. SARS-CoV-2 data were collected from the emerging literature. The infectivity of the virus in feces was estimated based on a range of assumption between viral genome equivalence and infectious unit. The human exposure dose was calculated using Monte Carlo simulation of viral concentrations in aerosols under each scenario and human breathing rates. The probability of COVID-19 illness was generated using the dose-response model for SARS-CoV-1, a close relative of SARS-CoV-2, that was responsible for the SARS outbreak in 2003. The results indicate the median risks of developing COVID-19 for a single day exposure is 1.11 × 10 −10 and 3.52 × 10 −11 for toilet flushing and faulty drain scenario, respectively. The worst case scenario predicted the high end of COVID-19 risk for the toilet flushing scenario was 5.78 × 10 −4 (at 95th percentile). The infectious viral loads in human feces are the most sensitive input parameter and contribute significantly to model uncertainty.

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“…An effective treatment step in retaining bacterial pathogens is a membrane bioreactor (MBR) ( Wu 2019 ). Nevertheless, opportunistic pathogens such as P. aeruginosa and L. pneumophila can grow after treatment due to remaining nutrients and nonsterile conditions and can cause serious hygienic problems for greywater reuse ( Blanky et al. 2017 , Friedler et al.…”

Section: Introductionmentioning

confidence: 99%

Stagnation leads to short-term fluctuations in the effluent water quality of biofilters: A problem for greywater reuse?

Hess

Baum

Schiessl³

et al. 2021

Water Research X

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Highlights A greywater treatment system was monitored with automated flow cytometry and turbidity. Stagnation in biological activated carbon filter led to peaks in total cell concentration and turbidity. Strong correlation was observed between TCC and turbidity. Stagnation did not lead to increase of opportunistic pathogens in the biofilter's effluent.

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Greywater reuse - Assessment of the health risk induced by Legionella pneumophila

Cited by 37 publications

References 45 publications

Flushing of stagnant premise water systems after the COVID-19 shutdown can reduce infection risk by Legionella and Mycobacterium spp

Flushing of stagnant premise water systems after the COVID-19 shutdown can reduce infection risk by Legionella and Mycobacterium spp

Quantifying the risk of indoor drainage system in multi-unit apartment building as a transmission route of SARS-CoV-2

Stagnation leads to short-term fluctuations in the effluent water quality of biofilters: A problem for greywater reuse?

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