Research

15 pages, 3433 KiB

Open AccessFeature PaperArticle

Quantitative Microbial Risk Analysis for Various Bacterial Exposure Scenarios Involving Greywater Reuse for Irrigation

by Allison Busgang, Eran Friedler, Yael Gilboa and Amit Gross

Water 2018, 10(4), 413; https://doi.org/10.3390/w10040413 - 02 Apr 2018

Cited by 33 | Viewed by 5827

Greywater reuse can significantly reduce domestic water consumption. While the benefits are promising, risks are still under debate. Using a quantitative microbial risk-assessment model, we assessed the health risks associated with greywater reuse. The pathogens Salmonella enterica, Shigella spp., and Staphylococcus aureus [...] Read more.

Greywater reuse can significantly reduce domestic water consumption. While the benefits are promising, risks are still under debate. Using a quantitative microbial risk-assessment model, we assessed the health risks associated with greywater reuse. The pathogens Salmonella enterica, Shigella spp., and Staphylococcus aureus were evaluated due to their possible prevalence in greywater and limited information regarding their potential risk with relation to greywater reuse for irrigation. Various exposure scenarios were investigated. Monte Carlo simulation was used and results were compared to the maximum “acceptable” limit of 10⁻⁶ disability-adjusted life years (DALY) set by the World Health Organization. Safe reuse was met for all worst-case exposure scenarios for Staphylococcus aureus, Salmonella enterica and Shigella spp. If their concentrations were kept below 10,000, 50 and 5 cfu/100 mL, respectively. For the best-practice (more realistic) scenarios, safe reuse was met for Staphylococcus aureus if its concentration was kept below 10⁶ cfu/100 mL. Salmonella enterica met the safe reuse requirements if a maximum concentration of 500 cfu/100 mL was maintained and Shigella spp. if a maximum concentration was lower than 5 cfu/100 mL. Based on reported concentrations of these bacteria in greywater, proper treatment and disinfection are recommended. Full article

(This article belongs to the Special Issue Development of Alternative Water Sources in the Urban Sector)

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20 pages, 22529 KiB

Open AccessArticle

Pluvial Flood Risk Assessment Tool (PFRA) for Rainwater Management and Adaptation to Climate Change in Newly Urbanised Areas

by Szymon Szewrański, Jakub Chruściński, Jan Kazak, Małgorzata Świąder, Katarzyna Tokarczyk-Dorociak and Romuald Żmuda

Water 2018, 10(4), 386; https://doi.org/10.3390/w10040386 - 26 Mar 2018

Cited by 53 | Viewed by 9506

Abstract

The aim of this research is to develop the Pluvial Flood Risk Assessment tool (PFRA) for rainwater management and adaptation to climate change in newly urbanised areas. PFRA allows pluvial hazard assessment, as well as pluvial flood risk mapping. The original model was [...] Read more.

The aim of this research is to develop the Pluvial Flood Risk Assessment tool (PFRA) for rainwater management and adaptation to climate change in newly urbanised areas. PFRA allows pluvial hazard assessment, as well as pluvial flood risk mapping. The original model was created using ArcGIS software with the ArcHydro extension, and the script was written using the Python programming language. The PFRA model effectively combines information about land cover, soils, microtopography (LiDAR data), and projected hydro-meteorological conditions, which enables the identification of the spatial and temporal distribution of pluvial flood risks in newly developed areas. Further improvements to the PFRA concern the quantification of pluvial flood-related damages, the application of high resolution precipitation data, and the optimisation of coding. Full article

(This article belongs to the Special Issue Development of Alternative Water Sources in the Urban Sector)

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14 pages, 3861 KiB

Open AccessArticle

Treatability of a Highly-Impaired, Saline Surface Water for Potential Urban Water Use

by Frederick Pontius

Water 2018, 10(3), 324; https://doi.org/10.3390/w10030324 - 15 Mar 2018

Cited by 5 | Viewed by 4639

Abstract

As freshwater sources of drinking water become limited, cities and urban areas must consider higher-salinity waters as potential sources of drinking water. The Salton Sea in the Imperial Valley of California has a very high salinity (43 ppt), total dissolved solids (70,000 mg/L), [...] Read more.

As freshwater sources of drinking water become limited, cities and urban areas must consider higher-salinity waters as potential sources of drinking water. The Salton Sea in the Imperial Valley of California has a very high salinity (43 ppt), total dissolved solids (70,000 mg/L), and color (1440 CU). Future wetlands and habitat restoration will have significant ecological benefits, but salinity levels will remain elevated. High salinity eutrophic waters, such as the Salton Sea, are difficult to treat, yet more desirable sources of drinking water are limited. The treatability of Salton Sea water for potential urban water use was evaluated here. Coagulation-sedimentation using aluminum chlorohydrate, ferric chloride, and alum proved to be relatively ineffective for lowering turbidity, with no clear optimum dose for any of the coagulants tested. Alum was most effective for color removal (28 percent) at a dose of 40 mg/L. Turbidity was removed effectively with 0.45 μm and 0.1 μm microfiltration. Bench tests of Salton Sea water using sea water reverse osmosis (SWRO) achieved initial contaminant rejections of 99 percent salinity, 97.7 percent conductivity, 98.6 percent total dissolved solids, 98.7 percent chloride, 65 percent sulfate, and 99.3 percent turbidity. Full article

(This article belongs to the Special Issue Development of Alternative Water Sources in the Urban Sector)

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19 pages, 2139 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Improving the Multi-Objective Performance of Rainwater Harvesting Systems Using Real-Time Control Technology

by Wei D. Xu, Tim D. Fletcher, Hugh P. Duncan, David J. Bergmann, Jeddah Breman and Matthew J. Burns

Water 2018, 10(2), 147; https://doi.org/10.3390/w10020147 - 02 Feb 2018

Cited by 58 | Viewed by 8624

Abstract

Many studies have identified the potential of rainwater harvesting (RWH) systems to simultaneously augment potable water supply and reduce delivery of uncontrolled stormwater flows to downstream drainage networks. Potentially, such systems could also play a role in the controlled delivery of water to [...] Read more.

Many studies have identified the potential of rainwater harvesting (RWH) systems to simultaneously augment potable water supply and reduce delivery of uncontrolled stormwater flows to downstream drainage networks. Potentially, such systems could also play a role in the controlled delivery of water to urban streams in ways which mimic baseflows. The performance of RWH systems to achieve these three objectives could be enhanced using Real-Time Control (RTC) technology to receive rainfall forecasts and initiate pre-storm release in real time, although few studies have explored such potential. We used continuous simulation to model the ability of a range of allotment-scale RWH systems to simultaneously deliver: (i) water supply; (ii) stormwater retention; and (iii) baseflow restoration. We compared the performance of RWH systems with RTC technology to conventional RWH systems and also systems designed with a passive baseflow release, rather than the active (RTC) configuration. We found that RWH systems employing RTC technology were generally superior in simultaneously achieving water supply, stormwater retention and baseflow restoration benefits compared with the other types of system tested. The active operation provided by RTC allows the system to perform optimally across a wider range of climatic conditions, but needs to be carefully designed. We conclude that the active release mechanism employing RTC technology exhibits great promise; its ability to provide centralised control and failure detection also opens the possibility of delivering a more reliable rainwater harvesting system, which can be readily adapted to varying climate over both the short and long term. Full article

(This article belongs to the Special Issue Development of Alternative Water Sources in the Urban Sector)

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575 KiB

Open AccessArticle

Newspaper Coverage of Potable Water Recycling at Orange County Water District’s Groundwater Replenishment System, 2000–2016

by Kerri Jean Ormerod and Leann Silvia

Water 2017, 9(12), 984; https://doi.org/10.3390/w9120984 - 16 Dec 2017

Cited by 9 | Viewed by 6361

Abstract

Water planners in water-strapped communities in the western United States and beyond increasingly consider potable water recycling an important water management strategy. Although potable water recycling can increase an otherwise limited urban water supply, the threat of public or political opposition often looms [...] Read more.

Water planners in water-strapped communities in the western United States and beyond increasingly consider potable water recycling an important water management strategy. Although potable water recycling can increase an otherwise limited urban water supply, the threat of public or political opposition often looms large. This paper examines newspaper coverage of the most widely celebrated potable water reuse project in the world—the Groundwater Replenishment System (GWRS) in Orange County, California, USA. The case study examines the coverage of GWRS contained in local, national, and international newspapers during an era of significant investment and repeated expansion. Despite the potential controversy associated with drinking recycled wastewater, there was no negative newspaper coverage of GWRS from 2000–2016. Much of the coverage was mundane, however several articles embraced infrastructure and technology as key to developing new water resources while protecting public and environmental health. Although potable water recycling is presented as an innovative solution capable of solving several problems at once, a close analysis reveals that recycled water may not fulfill the promise of an uninterruptible urban water supply. Full article

(This article belongs to the Special Issue Development of Alternative Water Sources in the Urban Sector)

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678 KiB

Open AccessFeature PaperArticle

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

by David C. Shoults and Nicholas J. Ashbolt

Water 2017, 9(12), 963; https://doi.org/10.3390/w9120963 - 11 Dec 2017

Cited by 5 | Viewed by 4231

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 [...] Read more.

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 Lysostaphin^TM 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. Full article

(This article belongs to the Special Issue Development of Alternative Water Sources in the Urban Sector)

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5343 KiB

Open AccessFeature PaperArticle

Water Saving and Cost Analysis of Large-Scale Implementation of Domestic Rain Water Harvesting in Minor Mediterranean Islands

by Alberto Campisano, Giuseppe D’Amico and Carlo Modica

Water 2017, 9(12), 916; https://doi.org/10.3390/w9120916 - 25 Nov 2017

Cited by 25 | Viewed by 5750

Abstract

This paper describes a novel methodology to evaluate the benefits of large-scale installation of domestic Rain Water Harvesting (RWH) systems in multi-story buildings. The methodology was specifically developed for application to small settlements of the minor Mediterranean islands characterized by sharp fluctuations in [...] Read more.

This paper describes a novel methodology to evaluate the benefits of large-scale installation of domestic Rain Water Harvesting (RWH) systems in multi-story buildings. The methodology was specifically developed for application to small settlements of the minor Mediterranean islands characterized by sharp fluctuations in precipitation and water demands between winter and summer periods. The methodology is based on the combined use of regressive models for water saving evaluation and of geospatial analysis tools for semi-automatic collection of spatial information at the building/household level. An application to the old town of Lipari (Aeolian islands) showed potential for high yearly water savings (between 30% and 50%), with return on investment in less than 15 years for about 50% of the installed RWH systems. Full article

(This article belongs to the Special Issue Development of Alternative Water Sources in the Urban Sector)

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3046 KiB

Open AccessFeature PaperArticle

Use of Cotton as a Carbon Source for Denitrification in Biofilters for Groundwater Remediation

by Amir Aloni and Asher Brenner

Water 2017, 9(9), 714; https://doi.org/10.3390/w9090714 - 18 Sep 2017

Cited by 23 | Viewed by 5493

Abstract

This study is part of a comprehensive research aimed at the development and application of the “Water Sensitive Cities” idea in Israel. This is a sustainable concept, incorporating among others the harvesting, treatment, and reuse of storm-water. The use of engineered biofiltration systems [...] Read more.

This study is part of a comprehensive research aimed at the development and application of the “Water Sensitive Cities” idea in Israel. This is a sustainable concept, incorporating among others the harvesting, treatment, and reuse of storm-water. The use of engineered biofiltration systems for the harvesting and treatment of storm-water in Israel is complicated due to the prolonged dry climate period, spanning 7–8 months of the year. Therefore, the tactic suggested is to use a hybrid biofiltration system for both storm-water harvesting/polishing during winter, and for remediation of nitrate-contaminated groundwater during summer. This paper focuses on the summer design (denitrification) configuration. In preliminary experiments, it was found that crude cotton could serve as an effective carbon source for denitrification. Further results are reported herein regarding the design and operation of biofilter columns applied for the treatment of synthetic mixtures simulating nitrate-contaminated groundwater. The columns were composed of crude cotton wool and polyethylene beads, which prevented the effect of cotton compression. This application was shown to enable controlled removal of nitrate to low levels, while emitting very low concentrations of total organic carbon (TOC) and nitrite. It was also concluded that a biofilter requires judicious design and operation, since complete removal of nitrogen oxides might lead to the formation of undesired compounds such as sulfides due to the development of anaerobic conditions. Full article

(This article belongs to the Special Issue Development of Alternative Water Sources in the Urban Sector)

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2871 KiB

Open AccessFeature PaperArticle

End-User Cost-Benefit Prioritization for Selecting Rainwater Harvesting and Greywater Reuse in Social Housing

by Isabel Domínguez, Sarah Ward, Jose Gabriel Mendoza, Carlos Iván Rincón and Edgar Ricardo Oviedo-Ocaña

Water 2017, 9(7), 516; https://doi.org/10.3390/w9070516 - 12 Jul 2017

Cited by 23 | Viewed by 7694

Abstract

Rainwater harvesting (RWH) and greywater reuse (GWR) are increasingly being considered at the building-level to achieve multiple goals. Cost-benefit assessments facilitate decision-making; however, most are focused on large-scale systems with limited information available for households from developing countries. To better understand the prioritization [...] Read more.

Rainwater harvesting (RWH) and greywater reuse (GWR) are increasingly being considered at the building-level to achieve multiple goals. Cost-benefit assessments facilitate decision-making; however, most are focused on large-scale systems with limited information available for households from developing countries. To better understand the prioritization of costs and benefits by potential end-users in this context, this paper presents an assessment of an RWH/GWR system in low income, low consumption households in a social housing development in Colombia. From an initial household consultation, preferences related to the use of RWH/GWR were identified and three alternatives were proposed and designed. In a follow-up consultation, potential end-users were engaged with the cost-benefit of the proposed alternatives. Potential end-users prioritized the selection of the system with potable water savings of 25%, a payback period of 30 years, an internal return rate of 4.7%, and a Benefit/Cost ratio of 1.3. Of the three alternatives, this system had the median payback period, highest investment, and highest maintenance cost, but also the highest volumetric water saving and highest water and sewerage bill savings. In contrast to findings from developed countries, this indicates that minimising the cost may not be the primary decision making criteria in some developing country contexts, where perhaps a greater value is placed on conserving water resources. Full article

(This article belongs to the Special Issue Development of Alternative Water Sources in the Urban Sector)

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