Overuse of antibiotics is accelerating the spread of resistance risk in the environment. In drinking water supply systems, the effect of antibiotics on the resistance of biofilm is unclear, and there ...have been few studies in disinfectant-containing systems. Here, we designed a series of drinking water supply reactors to investigate the effects of antibiotics on biofilm and bacteria in the water. At low concentrations, antibiotics could promote the growth of bacteria in biofilm; among the tested antibiotics (tetracycline, sulfadiazine and chloramphenicol), tetracycline had the strongest ability to promote this. And the antibiotic resistant bacteria (ARB) could inhibit the growth of bacteria in drinking water. Results have shown that antibiotics enhanced the bacterial chlorine resistance in the effluent, but reduced that in the biofilm. Furthermore, metagenomic analysis showed that antibiotics reduced the richness of biofilm communities. The dominant phyla in the biofilm were Proteobacteria, Planctomycetes, and Firmicutes. In tetracycline-treated biofilm, the dominant phylum was Planctomycetes. In sulfadiazine- and chloramphenicol-treated groups, bacteria with complex cell structures preferentially accumulated. The dominant class in biofilm in the ARB-added group was Gammaproteobacteria. The abundance of antibiotic resistant genes (ARGs) was correlated with biofilm community structure. This study shows that antibiotics make the biofilm community structure of drinking water more resistant to chlorine. ARGs may be selective for certain bacteria in the process, and there may ultimately be enhanced chlorine and antibiotic resistance of effluent bacteria in drinking water.
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•Low concentrations of antibiotics can promote the growth of biofilm.•Antibiotics decreased the difference in chlorine resistance between the biofilm and effluent bacteria.•Antibiotics reduced the richness and diversity of biofilm communities.•The dominant bacteria of biofilm under antibiotics were chlorine resistant bacteria.•The abundance of sul is positively related to the proportion of Planctomycetes in the microbial community.
Low concentrations of antibiotics in drinking water systems can promote the growth of bacteria in biofilm, and make biofilm community structure more resistant to chlorine.
To date, experimental and epidemiological evidence of endocrine disrupting compounds (EDCs) adversely affecting human and animal populations has been widely debated. Notably, human health risk ...assessment is required for risk mitigation. The lack of human health risk assessment and management may thus unreliably regulate the quality of water resources and efficiency of treatment processes. Therefore, drinking water supply systems (DWSSs) may be still unwarranted in assuring safe access to potable drinking water. Drinking water supply, such as tap water, is an additional and crucial route of human exposure to the health risks associated with EDCs. A holistic system, incorporating continuous research in DWSS monitoring and management using multi-barrier approach, is proposed as a preventive measure to reduce human exposure to the risks associated with EDCs through drinking water consumption. The occurrence of EDCs in DWSSs and corresponding human health risk implications are analyzed using the Needs, Approaches, Benefits, and Challenges (NABC) method. Therefore, this review may act as a supportive tool in protecting human health and environmental quality from EDCs, which is essential for decision-making regarding environmental monitoring and management purposes. Subsequently, the public could have sustainable access to safer and more reliable drinking water.
•Presence of EDCs in global drinking water supplies is risky to public health.•Humans are potentially exposed to EDCs via drinking water consumption.•EDCs influence physiological functions of exposed individuals.•NABC analysis gives political/economic/social insights into safe drinking water.•A holistic approach is proposed to reduce human exposure to EDCs.
Graphene oxide (GO)-enhanced membranes are being developed to solve major limitations in both reverse osmosis (RO) and membrane distillation (MD) technologies, which include high electricity and ...thermal energy consumption. This study performed, for the first time, a life cycle assessment to determine the effects of using GO-enhanced membranes on the environmental impacts of seawater desalination via RO and MD. Four scenarios were evaluated and eighteen environmental impacts were quantified according to the ReCiPe impact assessment method. The average impacts for the RO-GO scenarios were lower than those of RO by 3–7 %. The reduction in the climate change impact was 3–8 %, which could avoid the release of 380–850 kt CO2 eq. per year globally if these membranes were used in current seawater RO systems. The MD-GO scenarios had, on average, 27–34 % lower impacts than the MD scenarios. Overall, the RO-GO systems were the most favourable, with lower impacts than MD-GO for most categories. However, using solar-thermal energy instead of natural gas in MD desalination would lead to 43–93 % lower impacts in nine categories than RO powered predominantly by fossil fuels. This includes climate change, which would be 64 % lower; however, freshwater ecotoxicity would be more than four-times higher. The results of this work indicate the potential environmental benefits of GO-enhanced membranes and discuss the future developments needed to improve the performance of RO and MD.
•Graphene oxide reduces environmental impacts of membrane distillation by 27–34 %.•The reduction is much smaller for reverse osmosis (3–6.8 %).•Still, that would avoid emissions of 380,000–850,000 t CO2 eq. per year globally.•Reverse osmosis has much lower impacts than membrane distillation.•However, using renewable heat would make membrane distillation a better option.
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•The water-energy-food-ecosystem nexus concept is applied to assess drought conditions in Sweden.•Targeted standardized drought indices are chosen to represent different nexus ...sectors.•Sectors feature different response times to precipitation deficits and resulting drought durations, both of which are changing in the future.•Droughts become more frequent, longer and severe across most WEFE nexus sectors.•The energy sector is exceptional as it features fewer, shorter and less severe future droughts.
Droughts can affect a multitude of public and private sectors, with impacts developing slowly over time. While droughts are traditionally quantified in relation to the hydrological components of the water cycle that they affect, this manuscript demonstrates a novel approach to assess future drought conditions through the lens of the water-energy-food-ecosystem (WEFE) nexus concept. To this end, a set of standardized drought indices specifically designed to represent different nexus sectors across 50 catchments in Sweden was computed based on an ensemble of past and future climate model simulations. Different patterns in the response of the four nexus sectors water, energy, food and ecosystem services to future climate change emerged, with different response times and drought durations across the sectors. These results offer new insights into the propagation of drought through the WEFE nexus in cold climates. They further suggest that future drought projections can be better geared towards decision makers by basing them on standardized drought indices that were specifically tailored to represent particular nexus sectors.
Understanding the controls on spatial variability of groundwater arsenic (As) is critical for mitigating As contamination. The objective of this study is to determine controls on previously ...unexplained differences in groundwater As concentrations, which are high along the east bank and low along the west bank of the River Bhagirathi-Hoogly (B-H), the primary Indian distributary of the River Ganges, on the western margin of the Bengal basin. A total of 54 wells were sampled after the monsoon season at four sites (two each east and west of the B-H) in Murshidabad district, West Bengal, for field parameters, major and minor solutes, and stable isotopes of water. An additional four boreholes were drilled for analyses of sediment texture, mineralogy, total organic and inorganic carbon, and total As and other metal(loid)s. Results show that higher As in east-bank groundwater (median 0.031 mg/L) is associated with generally more anoxic conditions (higher median total Fe and lower median EH and NO3−) relative to west-bank groundwater (median As < 0.001 mg/L), consistent with previous studies. In contrast, concentrations of Mn in the study area are highest in west-bank wells near the B-H. Carbonate and silicate weathering appear to be more important in east- and west-bank groundwater, respectively, which may reflect differences in sediment sources. Ranges of total As are similar in east- and west-bank sediments. Relatively depleted values of δ18O and δ2H in the east-bank aquifer and streams appear to reflect focused recharge through paleochannels, while relatively enriched west-bank values suggest diffuse recharge to upland aquifers. We speculate that water infiltrating through erosional, stratigraphic “windows” carries organic matter capable of mobilizing As in east-bank groundwater. This comprehensive evaluation of groundwater chemistry provides a more detailed understanding of controls on As variability within the basin.
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Beta-lactamases (bla) are the largest class of antibiotic resistance genes (ARGs) and can survive drinking water treatment processes. However, the key influencing factors of bla genes and the control ...measures in drinking water supply systems (DWSSs) remain unclear. Quantitative PCR, metagenomic, and 16S rRNA gene sequencing assays were performed to investigate the bla genes in the DWSS. The main carriers of bla genes are genera Caenimonas and Sphingomonas, which were the dominant bacterial genera in the DWSS. The abundance of bla genes was associated with bacterial community assembly events. When the heterotrophic plate count (HPC) in water was below 500 CFU/mL, stochastic assembly was the major contributor to bacterial community assembly and the bacterial community was less affected by the environment. When the HPC in water was above 500 CFU/mL, deterministic assembly played an important role and decreasing the organic matter improved the efficiency of bla genes control. Organic matter can affect bla genes by shifting the diversity of the microbial community, and less organic matter appeared to be beneficial to reducing the bacterial niche width in the DWSS. Nanofiltration (NF) can decrease the effluent organic matter in waterworks and slow the dissemination of bacteria carrying bla genes in the DWSS.
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•Less organic matter was beneficial to reducing the bacterial niche width in the DWSS.•It is more effective to control bla in high HPC water with deterministic bacterial assembly.•Organic matter influences bla genes by shifting microbial community diversity.•Nanofiltration is effective for the control of organics and bla genes in the DWDS.
Fresh water, despite being a renewable natural resource, is currently limited and scarce. Its necessity for life and economic growth has led to permanent conflicts of interest. Social and sectoral ...dynamics regarding water entail conflicts over use, alterations of natural conditions, effects on its availability, quantity and quality. Due to anthropic activities present in watersheds, freshwater systems around the world face the emergence of innumerable chemical substances that hinder their treatment possesses and favor the formation of other compounds. These include disinfection byproducts (DBPs), which are compounds that represent a risk to human health due to its mutagenic and carcinogenic nature. This study conducts a systematic review of the literature concerning DBPs in drinking water supply systems (DWSS). From the research questions formulated in the review, a knowledge gap has been identified, which suggests the problems linked to the appearance of DBPs in treated water, should be addressed within an interdisciplinary and systemic approach. This implies the development of methodological, sociological, ecological and technological processes that allow an understanding of the problem from a holistic and integrative perspective. The occurrence of DBPs in drinking water treatment plants cannot be reduced to the product of chemical reactions between precursors and disinfectant agents such as chlorine; on the contrary, the problem presumes a much more complex origin that requires an analysis of the actions and processes that are carried out in territories and potentiate the deleterious processes in terms of water quality.
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•8 contribution categories were identified through the analysis of the selected 367 research and review, peer-reviewed papers.•Literature mostly focuses on studying and observing the different human health risks, particularly the emergence of DBPs related Cancer.•The most recent reviewed studies have started to incorporate previously unutilized variables such as those related to climate, geography and of anthropic origin.•The concepts of social ecological systems and vulnerability are presented as viable options towards the evaluation of DBPs as a multidimensional subject.
Conversion of natural land cover can degrade water quality in water supply watersheds and increase treatment costs for Public Water Systems (PWSs), but there are few studies that have fully evaluated ...land cover and water quality relationships in mixed use watersheds across broad hydroclimatic settings. We related upstream land cover (forest, other natural land covers, development, and agriculture) to observed and modeled water quality across the southeastern US and specifically at 1746 PWS drinking water intake facilities. While there was considerable complexity and variability in the relationship between land cover and water quality, results suggest that Total Nitrogen (TN), Total Phosphorus (TP) and Suspended Sediment (SS) concentrations decrease significantly with increasing forest cover, and increase with increasing developed or agricultural cover. Catchments with dominant (>90 %) agricultural land cover had the greatest export rates for TN, TP, and SS based on SPARROW model estimates, followed by developed-dominant, then forest- and other-natural-dominant catchments. Variability in modeled TN, TP, and SS export rates by land cover type was driven by variability in natural background sources and catchment characteristics that affected water quality even in forest-dominated catchments. Both intake setting (i.e., run-of-river or reservoir) and upstream land cover were important determinants of water quality at PWS intakes. Of all PWS intakes, 15 % had high raw water quality, and 85 % of those were on reservoirs. Of the run-of-river intakes with high raw water quality, 75 % had at least 50 % forest land cover upstream. In addition, PWS intakes obtaining surface water supply from smaller upstream catchments may experience the largest losses of natural land cover based on projections of land cover in 2070. These results illustrate the complexity and variability in the relationship between land cover and water quality at broad scales, but also suggest that forest conservation can enhance the resilience of drinking water supplies.
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•Land cover and water quality were linked regionally and at public water intakes.•Nutrient and sediment concentrations decreased with increasing forest land cover.•Both intake setting and land cover were important determinants of water quality.•Small watersheds may experience the largest losses of natural land cover by 2070.
In recent years, the presence of micropollutants in drinking water has become an issue of growing global concern. Due to their low concentrations, monitoring databases are usually rich in censored ...data (e.g. samples with concentrations reported below the limit of quantification, LOQ) which are typically eliminated or replaced with a value arbitrarily chosen between 0 and LOQ. These conventional methods have some limitations and can lead to erroneous conclusions on: presence of micropollutants in the source water, treatment efficiencies, produced water quality and associated human health risk. In this work, an advanced approach, based on Maximum Likelihood Estimation method for left-censored data (MLELC), was applied on monitoring data of 19 contaminants (metals, volatile organic compounds, pesticides and perfluorinated compounds) in 5362 groundwater (GW) and 12,344 drinking water (DW) samples, collected from 2012 to 2017 in 28 drinking water treatment plants in an urbanized area. This study demonstrates the benefits of MLELC method, especially for high percentages of censored data. Data are used to build statistical distributions which can be effectively used for several applications, such as the time trend evaluation of GW micropollutant concentrations and the estimation of treatment removal efficiency, highlighting the adequacy or the need for an upgrade. Moreover, the MLELC method has been applied to assess the human health risk associated with micropollutants, indicating the high discrepancy in the estimations obtained with conventional methods, whose results do not follow precautionary or sustainability criteria.
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•Conventional and advanced methods to treat censored concentration data are evaluated.•Drinking water concentration data collected from source to tap are analyzed.•Methods’ goodness of fitting data to probability distributions is examined.•Results on compounds time trend, removal efficiency and risk assessment are compared.•The effects of censored percentage and analytical method sensitivity are assessed.
An Internet questionnaire was conducted to determine the effects of the provision of information on public awareness regarding the drinking water supply. We targeted a total of 700 young people in ...their 20s and 30s, whose awareness of water supply services is particularly low compared to other age groups. The results indicated that information provision enhanced a sense of ownership, awareness of drinking water supply sustainability, and increased interest in 51.4% of the experimental group. A relationship was found between interest and recognition of water supply service, indicating the importance of raising interest, especially among those with no interest. Conversely, we found that information provision led to both agreement and disagreement on strengthening the financial basis of water utilities. We also found that people do not always understand the fact of a decrease in water tariff income due to the declining population as a risk. Furthermore, by analyzing free description of the reason for acceptance of the water tariff increase, we showed the contents of the PR that should be emphasized in the future.
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