Evaluation of microbiological risks associated with direct potable reuse

Although reclaimed water for potable applications has many potential benefits, it poses concerns for chemical and microbial risks to consumers. We present a quantitative microbial risk assessment (QMRA) Monte Carlo framework to compare a de facto water reuse scenario (treated wastewater-impacted surface water) with four hypothetical Direct Potable Reuse (DPR) scenarios for Norovirus, Cryptosporidium, and Salmonella. Consumer microbial risks of surface source water quality (impacted by 0–100% treated wastewater effluent) were assessed. Additionally, we assessed risks for different blending ratios (0–100% surface water blended into advanced-treated DPR water) when source surface water consisted of 50% wastewater effluent. De facto reuse risks exceeded the yearly 10−4 infections risk benchmark while all modeled DPR risks were significantly lower. Contamination with 1% or more wastewater effluent in the source water, and blending 1% or more wastewater-impacted surface water into the advanced-treated DPR water drove the risk closer to the 10−4 benchmark. We demonstrate that de facto reuse by itself, or as an input into DPR, drives microbial risks more so than the advanced-treated DPR water. When applied using location-specific inputs, this framework can contribute to project design and public awareness campaigns to build legitimacy for DPR.

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“…A similar approach has been used to pool risks from multiple pathogens by previous QMRA studies [12,61,62].

P_{i n f, d a i l y, t o t a l} = 1 - \prod_{1}^{n_{r e f}} (1 - P_{i n f, d a i l y, r e f})

…”

Section: Methodsmentioning

confidence: 99%

Drivers of Microbial Risk for Direct Potable Reuse and de Facto Reuse Treatment Schemes: The Impacts of Source Water Quality and Blending

Chaudhry

Hamilton

Haas

et al. 2017

IJERPH

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“…Specifying other operational or dosing parameters was unnecessary for the purposes of this study. Coupled with the conventional WWTPs, each of these DPR treatment trains is capable of achieving the pathogen log removal values recommended for potable reuse, even without the additional treatment at RMWTF (Amoueyan et al, ; Soller et al, ; Tchobanoglous et al, ), but there are other water quality implications that will be discussed later.…”

Section: Methodsmentioning

confidence: 99%

“…A more comprehensive triple bottom line analysis might even be warranted because of its ability to simultaneously consider the social, environmental, and economic implications of an engineering design (Haak, Sundaram, & Pagilla, ; Schimmoller, Kealy, & Foster, ; Schoen et al, ). With respect to social considerations, the recent literature demonstrates that, when designed and operated properly, potable reuse systems provide adequate protection of public health (Amoueyan, Ahmad, Eisenberg, & Gerrity, ; Amoueyan, Ahmad, Eisenberg, Pecson, & Gerrity, ; Chaudhry, Hamilton, Haas, & Nelson, ; Pecson et al, ; Pecson, Trussell, Pisarenko, & Trussell, ; Soller, Eftim, Warren, & Nappier, ). Particularly in California, potable reuse treatment trains often use both low‐pressure and high‐pressure (i.e., reverse osmosis [RO]) membranes, but when not mandated by local regulations or necessitated by salinity management, the use of membranes may lead to excessive costs or overall sustainability concerns (Bradshaw et al, ; Schimmoller et al, ).…”

Section: Introductionmentioning

confidence: 99%

Evaluating the sustainability of indirect potable reuse and direct potable reuse: a southern Nevada case study

et al. 2019

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This case study presents a framework for evaluating the sustainability of indirect potable reuse (IPR) and direct potable reuse (DPR) in Las Vegas, Nevada. A system dynamics model was developed to simulate population growth, water supply, water quality, energy costs, net present worth (NPW), and greenhouse gas (GHG) emissions. The model confirmed that DPR could achieve a net reduction in energy costs of up to US$250 million while still ensuring an adequate water supply. However, the high NPW of DPR ($1.0-$4.0 billion) relative to the status quo IPR approach ($0.6 billion) represents a significant economic hurdle, although future monetization of salt loadings and GHGs could reduce that disparity. DPR with ozone-biofiltration would also be hindered by an estimated concentration of total dissolved solids of up to 1,300 mg/L. Despite these barriers to implementation in Las Vegas, certain site-specific conditions may make DPR more attractive in other locations. K E Y W O R D S direct potable reuse, indirect potable reuse, net present worth, sustainability, system dynamics, water supply

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“…The parameter P s ill describes the probability of a GI illness from each reference pathogen (representing a fecal source). The formula computes the overall risk in the case that the individual risks are low or high, ensuring that a total probability risk value is below one [38].…”

Section: Calculating Total Probability Of Illness For a Mixture Of Fementioning

confidence: 99%

Human Health Risks Associated with Recreational Waters: Preliminary Approach of Integrating Quantitative Microbial Risk Assessment with Microbial Source Tracking

Gitter

Mena

Wagner³

et al. 2020

Water

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Gastrointestinal (GI) illness risks associated with exposure to waters impacted by human and nonhuman fecal sources were estimated using quantitative microbial risk assessment (QMRA). Microbial source tracking (MST) results had identified Escherichia coli (E. coli) contributors to the waterbody as human and unidentified (10%), cattle and domestic animals (25%), and wildlife (65%) in a rural watershed. The illness risks associated with ingestion during recreation were calculated by assigning reference pathogens for each contributing source and using pathogen dose–response relationships. The risk of GI illness was calculated for a specific sampling site with a geometric mean of E. coli of 163 colony forming units (cfu) 100 mL−1, and the recreational standard of E. coli, 126 cfu 100 mL−1. While the most frequent sources of fecal indicator bacteria at the sampling site were nonhuman, the risk of illness from norovirus, the reference pathogen representing human waste, contributed the greatest risk to human health. This study serves as a preliminary review regarding the potential for incorporating results from library-dependent MST to inform a QMRA for recreational waters. The simulations indicated that identifying the sources contributing to the bacterial impairment is critical to estimate the human health risk associated with recreation in a waterbody.

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Evaluation of microbiological risks associated with direct potable reuse

Cited by 59 publications

References 61 publications

Drivers of Microbial Risk for Direct Potable Reuse and de Facto Reuse Treatment Schemes: The Impacts of Source Water Quality and Blending

Drivers of Microbial Risk for Direct Potable Reuse and de Facto Reuse Treatment Schemes: The Impacts of Source Water Quality and Blending

Evaluating the sustainability of indirect potable reuse and direct potable reuse: a southern Nevada case study

Human Health Risks Associated with Recreational Waters: Preliminary Approach of Integrating Quantitative Microbial Risk Assessment with Microbial Source Tracking

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