Water

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16 pages, 1841 KiB

Open AccessFeature PaperArticle

Occurrence of Antibiotic-Resistant Genes and Bacteria in Household Greywater Treated in Constructed Wetlands

by Michelle Henderson, Sarina J. Ergas, Kebreab Ghebremichael, Amit Gross and Zeev Ronen

Water 2022, 14(5), 758; https://doi.org/10.3390/w14050758 - 27 Feb 2022

Cited by 9 | Viewed by 3068

There is a growing body of knowledge on the persistence of antibiotic-resistant genes (ARGs) and antibiotic-resistant bacteria (ARB) in greywater and greywater treatment systems such as constructed wetlands (CWs). Our research quantified ARGs (sul1, qnrS, and bla_CTXM32), class [...] Read more.

There is a growing body of knowledge on the persistence of antibiotic-resistant genes (ARGs) and antibiotic-resistant bacteria (ARB) in greywater and greywater treatment systems such as constructed wetlands (CWs). Our research quantified ARGs (sul1, qnrS, and bla_CTXM32), class one integron (intI1), and bacterial marker (16S) in four recirculating vertical flow CWs in a small community in the Negev desert, Israel, using quantitative polymerase chain reaction (qPCR). The greywater microbial community was characterized using 16S rRNA amplicon sequencing. Results show that CWs can reduce ARG in greywater by 1–3 log, depending on the gene and the quality of the raw greywater. Community sequencing results showed that the bacterial community composition was not significantly altered after treatment and that Proteobacteria, Epsilonbacteraeota, and Bacteroidetes were the most dominant phyla before and after treatment. Pseudomonas, Citrobacter, Enterobacter, and Aeromonas were the most commonly identified genera of the extended spectrum beta lactamase (ESBL) colonies. Some of the ESBL bacteria identified have been linked to clinical infections (Acinetobacter nosocomialis, Pseudomonas fulva, Pseudomonas putida, Pseudomonas monteilii, and Roseomonas cervicalis). It is important to monitor intI1 for the potential transfer of ARGs to pathogenic bacteria. Full article

(This article belongs to the Special Issue The Use of Greywater and Wastewater for Irrigation)

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16 pages, 1919 KiB

Open AccessArticle

Elevated Vertical-Flow Constructed Wetlands for Light Greywater Treatment

by Carlo Morandi, Gerhard Schreiner, Patrizia Moosmann and Heidrun Steinmetz

Water 2021, 13(18), 2510; https://doi.org/10.3390/w13182510 - 13 Sep 2021

Cited by 8 | Viewed by 3360

Abstract

Integrated planning of urban blue–green infrastructures is crucial to strengthen urban environmental quality and mitigate negative climate change-associated effects. It implies, however, increased water demand for irrigation, wherefore greywater (wastewater excluding wastewater from toilets and urinals) can be used, yet it requires handling [...] Read more.

Integrated planning of urban blue–green infrastructures is crucial to strengthen urban environmental quality and mitigate negative climate change-associated effects. It implies, however, increased water demand for irrigation, wherefore greywater (wastewater excluding wastewater from toilets and urinals) can be used, yet it requires handling for safe reuse. One treatment option is the use of constructed wetlands (CW), which have thus far not been broadly applied in inner-city districts due to large area requirements. This work investigates a novel bipartite container-based vertical-flow constructed wetland (VFCW) for the treatment of light greywater (from showers and hand wash basins) and its use as irrigation water for urban facade greenery. The VFCW consists of two compartments with 2.5 m² filter area each, filled with 75 cm zeolite-containing lava sand (0–4 mm) and 75 cm Rhine sand (0–2 mm), respectively. In short, screening has proven to be well suitable for coarse solids removal, so there is no further need to settle light greywater, which reduces overall treatment area and benefits urban application. Treated greywater complied with irrigation standards at all times, yet mixing with rainwater can help reduce salt contents, if applicable. The modular/elevated lava sand VFCW exhibited extensive nitrification, even at extremely low water temperatures, as well as mean effluent concentrations of 6.3 mg/L COD and <0.05 mg/L P_tot, which makes it a very promising treatment option for greywater. All in all, the modular/elevated design promotes urban application of VFCW as a multifunctional blue–green system that can help increase urban resilience. Full article

(This article belongs to the Special Issue The Use of Greywater and Wastewater for Irrigation)

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11 pages, 1632 KiB

Open AccessFeature PaperArticle

Onsite Chlorination of Greywater in a Vertical Flow Constructed Wetland—Significance of Trihalomethane Formation

by Anat Bernstein, Hagar Siebner, Andrew G. Kaufman and Amit Gross

Water 2021, 13(7), 903; https://doi.org/10.3390/w13070903 - 26 Mar 2021

Cited by 5 | Viewed by 2246

Abstract

To reduce public health hazards, greywater reuse may involve disinfection, which is often performed through chlorination. The formation of toxic disinfection by-products is a negative side-effect of chlorine’s reaction with organic matter, of which trihalomethanes (THM) are one of the most dominant (though [...] Read more.

To reduce public health hazards, greywater reuse may involve disinfection, which is often performed through chlorination. The formation of toxic disinfection by-products is a negative side-effect of chlorine’s reaction with organic matter, of which trihalomethanes (THM) are one of the most dominant (though not most toxic) groups. Greywater treatment in vertical flow constructed wetlands leads to a decrease in dissolved organic matter. We hypothesized that these dissolved organic carbon (DOC) changes would be reflected in differences in THM formation. Greywater samples, at different treatment levels (i.e., decreasing organic matter content), were exposed to 5 mg/L of chlorine for 1 h. THM formation in raw greywater samples was significantly lower than in the more treated (recirculated) samples, despite their significantly higher DO concentrations. This trend was verified in six different systems. Furthermore, this was also shown when greywater was exposed to higher chlorine doses (25 and 50 mg/L). It is suggested that the increase in THM formation for longer recirculated water is the result of two factors: competition between a higher number of reactive sites in the raw water’s organic matter, which leads to smaller THM yields, and changes in the abundance of THM formation moieties in the recirculated water’s DOC. The latter was reflected in the SUVA increase in the treated water. Overall, THM formation, following treated greywater chlorination at the lower chlorine concentration studied, is not expected to pose an environmental health risk when the water is reused for irrigation. Full article

(This article belongs to the Special Issue The Use of Greywater and Wastewater for Irrigation)

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12 pages, 1861 KiB

Open AccessFeature PaperArticle

Impact of Suspended Solids and Organic Matter on Chlorine and UV Disinfection Efficiency of Greywater

by Eran Friedler, Diana F. Chavez, Yuval Alfiya, Yael Gilboa and Amit Gross

Water 2021, 13(2), 214; https://doi.org/10.3390/w13020214 - 18 Jan 2021

Cited by 9 | Viewed by 4233

Abstract

Reusing greywater (GW) can lower domestic water consumption. However, the GW must be treated and disinfected for securing user health. This research studied at the laboratory scale, and in flow-through setups, which are generally used in full-scale GW treatment the disinfection efficiency of [...] Read more.

Reusing greywater (GW) can lower domestic water consumption. However, the GW must be treated and disinfected for securing user health. This research studied at the laboratory scale, and in flow-through setups, which are generally used in full-scale GW treatment the disinfection efficiency of the two commonly used technologies (a) chlorination and (b) low-pressure UV irradiation. The disinfection methods were studied under a commonly found range of total suspended solids (TSS; 3.9–233 mg/L) and 5-d biochemical oxygen demand (BOD₅) concentrations (0–107 mg/L) as a representative/proxy of bioavailable organic matter. The negative effect of TSS began even at low concentrations (<20 mg/L) and increased consistently with increasing TSS concentrations across all the concentrations tested. On the other hand, the negative effect of BOD₅ on FC inactivation was observed only when its concentration was higher than 50 mg/L. Multiple linear regression models were developed following the laboratory results, establishing a correlation between FC inactivation by either chlorination or UV irradiation and initial FC, TSS, and BOD₅ concentrations. The models were validated against the results from the flow-through reactors and explained the majority of the variability in the measured FC inactivation. Conversion factors between the laboratory scales and the flow-through reactor experiments were established. These enable the prediction of the required residual chlorine concentration or the UV dose needed for an on-site flow-through reactor. This approach is valuable from both operational and research perspectives. Full article

(This article belongs to the Special Issue The Use of Greywater and Wastewater for Irrigation)

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14 pages, 2194 KiB

Open AccessArticle

Cost–Benefit Evaluation of Decentralized Greywater Reuse Systems in Rural Public Schools in Chile

by Carolina Rodríguez, Rafael Sánchez, Natalia Rebolledo, Nicolás Schneider, Jennyfer Serrano and Eduardo Leiva

Water 2020, 12(12), 3468; https://doi.org/10.3390/w12123468 - 10 Dec 2020

Cited by 14 | Viewed by 3212

Abstract

Water scarcity is one of the most important climatic threats in recent times. In Chile, the north and north-central areas, with predominantly arid or semi-arid climates, have been strongly affected by the low availability of water, as well as by overexploitation of water [...] Read more.

Water scarcity is one of the most important climatic threats in recent times. In Chile, the north and north-central areas, with predominantly arid or semi-arid climates, have been strongly affected by the low availability of water, as well as by overexploitation of water resources derived from the negative effect caused by some sectors of the economy such as agriculture and mining. Only 53% of households in rural areas in Chile have access to drinking water from a public network. To date, some pilot greywater treatment systems have been implemented in rural public schools. This paper presents an economic analysis of pilot systems for greywater treatment from three case studies. The results showed that the implementation of these systems would not be economically feasible, since the initial investment costs can exceed USD 5200, which is not offset by the water savings. However, other benefits, such as thermal regulation, better life quality, and the feeling of well-being and satisfaction of students and teachers should be considered to be paramount for the evaluation of treatment systems. In addition, current levels of treated greywater could allow irrigation of 6.24, 5.68, and 3.56 m²/person in the Alejandro Chelén, El Guindo, and Pedro de Valdivia schools, respectively. These results contribute to a better understanding of the social role that should be applied to the evaluation of ecological systems that save water and improve the well-being of the population. Full article

(This article belongs to the Special Issue The Use of Greywater and Wastewater for Irrigation)

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13 pages, 1331 KiB

Open AccessEditor’s ChoiceArticle

Quantifying the Benefits of Residential Greywater Reuse

by Josh Byrne, Stewart Dallas, Martin Anda and Goen Ho

Water 2020, 12(8), 2310; https://doi.org/10.3390/w12082310 - 17 Aug 2020

Cited by 8 | Viewed by 4461

Abstract

There is paucity of data on the quantification of the benefits of residential greywater reuse via direct diversion. While estimates have been made based on modelling the potential mains water savings, it is also recognised that the practicalities of system operation and occupant [...] Read more.

There is paucity of data on the quantification of the benefits of residential greywater reuse via direct diversion. While estimates have been made based on modelling the potential mains water savings, it is also recognised that the practicalities of system operation and occupant behaviour introduce substantial variation to these estimates. Three single residential housing projects in Fremantle, Western Australia, undertaken over ten years with a substantial focus on water efficiency and mains water substitution, have provided an opportunity to quantify these benefits. All three dwellings were intensively metered and documented. This paper describes the learnings generated along the way, including the methodology developed to effectively integrate direct diversion greywater reuse into a productive garden, along with other water sources to satisfy landscape water demand. Importantly a robust quantification of actual greywater volumes and associated mains water savings was made. The publication of actual greywater volumes will significantly contribute to this field and go a long way towards validating the merits of residential greywater reuse on mains water savings when systems are properly installed and operated. Brief considerations are also provided for energy efficiency and financial assessment. Full article

(This article belongs to the Special Issue The Use of Greywater and Wastewater for Irrigation)

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15 pages, 2578 KiB

Open AccessArticle

Effects of Waterlogging with Different Water Resources on Plant Growth and Tolerance Capacity of Four Herbaceous Flowers in a Bioretention Basin

by Wen-Chi Yang, Kuan-Hung Lin, Chun-Wei Wu, Yu-Jie Chang and Yu-Sen Chang

Water 2020, 12(6), 1619; https://doi.org/10.3390/w12061619 - 06 Jun 2020

Cited by 9 | Viewed by 4582

Abstract

Extreme weather events have increased due to climate change. Bioretention basins can effectively alleviate urban flooding by short-term water retention. Reclaimed water (RW) is considered an alternative water resource during water shortages. In this study, the abilities for waterlogging tolerance of four herbaceous [...] Read more.

Extreme weather events have increased due to climate change. Bioretention basins can effectively alleviate urban flooding by short-term water retention. Reclaimed water (RW) is considered an alternative water resource during water shortages. In this study, the abilities for waterlogging tolerance of four herbaceous flowers (angelonia, narrow-leaf zinnia, celosia, and medallion flower) are investigated to screen suitable ornamental plants for bioretention basins, and the influence of RW on the plants is also evaluated. All plants were treated with 10 days of waterlogging (electrical conductivity (EC) of tap water = 110.0 μS·cm⁻¹) followed by a seven-day recovery. Angelonia (Angelonia salicariifolia Humb. & Bonpl) was not affected by waterlogging and showed the best performance, judged from the ornamental quality, photosynthesis rate, and leaf malondialdehyde (MDA) among the tested flowers. Photosynthesis of the narrow-leaf zinnia (Zinnia angustifolia Kunth) decreased during waterlogging but soon recovered after being drained. Celosia (Celosia argentea L.) and medallion flower (Melampodium paludosum Kunth) were significantly affected by waterlogging and did not recover after drainage, in terms of responses to both external and physiological reactions. Moreover, waterlogging by the simulated RW (EC = 542.4 μS·cm⁻¹) did not have negative impacts on angelonia and narrow-leaf zinnia, due to the reduced leaf malondialdehyde concentration of angelonia and retarded the decline in the net photosynthesis rate of narrow-leaf zinnia. Thus, RW could be used as an alternative irrigation water resource for bioretention basins during the dry season to maintain plant growth. Full article

(This article belongs to the Special Issue The Use of Greywater and Wastewater for Irrigation)

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16 pages, 1812 KiB

Open AccessFeature PaperArticle

Quantification and Characterization of Antimicrobial Resistance in Greywater Discharged to the Environment

by Seema Porob, Hillary A. Craddock, Yair Motro, Orly Sagi, Michael Gdalevich, Zubaida Ezery, Nadav Davidovitch, Zeev Ronen and Jacob Moran-Gilad

Water 2020, 12(5), 1460; https://doi.org/10.3390/w12051460 - 20 May 2020

Cited by 12 | Viewed by 3574

Abstract

In disenfranchised communities, untreated greywater (wastewater without sewage) is often environmentally discharged, resulting in potential human exposure to antimicrobial-resistant bacteria (ARB), including extended-spectrum beta-lactamase (ESBL) producers. We sought to examine the abundance of ARB, specifically ESBLs, and antimicrobial resistance genes (ARGs) in greywater [...] Read more.

In disenfranchised communities, untreated greywater (wastewater without sewage) is often environmentally discharged, resulting in potential human exposure to antimicrobial-resistant bacteria (ARB), including extended-spectrum beta-lactamase (ESBL) producers. We sought to examine the abundance of ARB, specifically ESBLs, and antimicrobial resistance genes (ARGs) in greywater from off-grid, pastoral Bedouin villages in Southern Israel. Greywater samples (n = 21) collected from five villages were analyzed to enumerate fecal coliforms and Escherichia coli. ESBL producers were recovered on CHROMagar ESBL and confirmed by VITEK^®2 (bioMerieux, Marcy l’Etoile, France) for identification and antimicrobial susceptibility testing. Total genomic DNA was extracted from greywater samples and quantitative PCR (qPCR) was used to determine relative abundance (gene copies/16S rRNA gene) of class 1 integron-integrase intI1, bla_TEM, bla_CTX-M-32, sul1, and qnrS. The mean count of presumptive ESBL-producing isolates was 4.5 × 10⁶ CFU/100 mL. Of 81 presumptive isolates, 15 ESBL producers were recovered. Phenotypically, 86.7% of ESBL producers were multi-drug resistant. Results from qPCR revealed a high abundance of intI1 (1.4 × 10⁻¹ gene copies/16S rRNA), sul1 (5.2 × 10⁻² gene copies/16S rRNA), and qnrS (1.7 × 10⁻² gene copies/16S rRNA) followed by bla_TEM (3.5 × 10⁻³ gene copies/16S rRNA) and bla_CTX-M-32 (2.2 × 10⁻⁵ gene copies/16S rRNA). Results from our study indicate that greywater can be a source of ARB, including ESBL producers, in settings characterized by low sanitary conditions and inadequate wastewater management. Full article

(This article belongs to the Special Issue The Use of Greywater and Wastewater for Irrigation)

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