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A water desalination idea with high-efficiency was presented, which employed a vacuum tube type solar distiller to stuffy-thermal distillation and raw water preheating, and also utilized the hydrophobic α-Al2O3 ceramic membrane distillation (HCMD) modules and preheated raw water to membrane distillation (MD). In order to show the potential of HCMD to improve the photo-thermal conversion efficiency of the vacuum tube type solar distiller, this study explored the thermal performance and water desalination capacity of HCMD module driven by the recovered latent heat of the vacuum tube type solar distiller. The research results indicate that the membrane flux of HCMD had a significant positive exponential correlation with the raw water temperature (Tr). The convective heat transfer coefficient (h) of the hot side surface of hydrophobic α-Al2O3 ceramic membrane (HCM) was positively correlated with Tr and the concentration of raw water (C). The effects of Tr and cooling water temperature (Tc) on the thermal efficiency (η) of HCMD had an interaction. The theoretical maximum of η was close to 67.8%, and the variation range of η corresponding to the temperature range of preheated raw water by the solar distiller was 8.32–42.90%. The rejection rate of the HCM for all measured ions in the raw water was greater than 99.96%. This research was of great theoretical guiding significance for realizing the engineering application of the solar-thermal membrane coupling water desalination system.

Research studies published so far on microplastics in drinking water prove that both, bottled and tap water, may contain microscopic plastic pieces. Their possible origin ranges from raw water over treatment processes to packaging material and distribution systems. Various analytical techniques were used, which provide more or less reliable results. Consequently, reported amounts of microplastics in drinking water are difficult to compare, if not incomparable, with each other and with studies on microplastics in other food. Projections on the total intake of microplastics by humans via foodstuff should be made with care. Conclusions on the major intake pathways are not justified, yet. Instead, harmonized, valid methods and more research are needed to reliably determine microplastics in drinking water and more complex foodstuff.

Safely managed drinking water for all is the United Nations Sustainable Development Goal 6.1. Achieving this goal is a challenge in rural areas. A strong partnership between users of a water treatment system was critical to the success of community-scale technological change. In this study, the efficiency of a water treatment system was evaluated after the implementation of a technological change in a rural area. This research was carried out in a community in Ecuador, which before the change in technology had a treatment system composed of gravel pre-filtration and slow filtration. This system did not guarantee adequate water quality, due to a notable increase in the color and turbidity levels of raw water; in addition to the growing demand for water in recent years. A new conventional treatment system was implemented consisting of: coagulation, flocculation, sedimentation, rapid filtration and disinfection. All the modernization works were carried out on the same infrastructure that had served as gravel pre-filters. Before modernization, samples of raw water and treated water were collected for six months. After the changes carried out, samples of raw and treated water were also collected for another six months. The parameters analyzed were: turbidity, color, pH, total dissolved solids, residual chlorine, nitrates, sulfates, phosphates, chlorides, alkalinity, total hardness and iron. The values of all the parameters analyzed improved after the modernization, indicating that the changes made in the treatment plant were successful. As a result, a conventional treatment to make water potable in rural areas has become a robust process that can operate within a wide range of water quality, improving the quality and quantity of drinking water.

The use of Moringa oleifera (MO) for cleaner processes in water treatment has been proposed to treat raw water for low-income locations for its abundant availability, low cost, reduced by-product generation, biodegradability, non-toxicity and multifunctional behavior. This review analyzed studies that used MO seeds in coagulation-flocculation processes, identifying the main proteins that presented coagulant activity. It was concluded that its most viable application would be as flocculation aid, since it was possible to reduce the concentration of the chemical coagulant with good removal results. Regarding the use of MO as adsorbent, studies could verify its potential to remove several water contaminants, such as pesticides, dyes and pharmaceuticals. Moreover, hybrid treatments have been investigated, however, a research gap could be verified regarding studies on pilot scale, which are fundamental for verifying the viability in water treatment plants. In this sense, the main trends, challenges and recommendations for further studies were assessed regarding the sustainable application of MO seeds in water treatment.

The current study presents, in detail, an experimental investigation for detecting four of high risk aldehyde compounds in water (acetaldehyde, formaldehyde, glyoxal, and methyl glyoxal). These compounds are normally formed in water in micrograms per liter, as by-products, after addition of ozone in the water treatment plants. For this study, 114 samples were taken from the raw and directly from the ozonated water of a drinking water treatment plant in Iraq, between August 2020 (54 samples) and September 2020 (60 samples). The samples were analyzed for their constituents — for aldehyde compounds — using a Gas Chromatography-Electron capture detector (GC-ECD) apparatus. In addition, the concentration of organic matters was measured via total organic carbon (TOC) and chemical oxygen demand (COD) tests, which were measured in accordance with the other technique for the checking of water. The results showed that in all analyzed samples there was a significant increase in the formaldehyde and acetaldehyde concentration in the water, after subjecting it to the ozonation process. In addition to that, noticeable concentrations of glyoxal (6.7 and 9.0 µg/L in August and September, respectively) and methyl glyoxal (12.6 and 12.1 µg/L in August and September, respectively, which were not detected in the raw water samples, appeared in those taken from the treated water. The conclusion obtained from this study was that the level of aldehydes formed in the water was dependent on the raw water characteristics and the amount of ozone added for disinfection purposes.

Fresh and clean water is basic need for human health. However unclean and impure water creates access to illness and many diseases which influence the economic growth of the country. A very traditional method i.e. SSF has been used for removing fine suspended particles, microbes, minerals and flocs present in water. The aim of this research article is to invent and install an economic and non-conventional slow sand filter for treating water to resolve the issues related with impure water. Deigned SSF has been operated under the hydraulic loading of 4.6296 L/sec/m2 and an operational period of one hour. Cross sectional area of bed has been taken as 0.0576 m2. This technique is a small-scale scheme and easily employed for intermittent use that made it suitable for household purpose. Four processes namely Mechanical trappings, Predation, Adsorption and Natural death that has been taken place during the filtration process has been widely discussed in this paper. Various chemical and physical characteristics of water has been tested. Major parameters like pH, TDS, turbidity, Salinity, conductivity and salinity of filtered water have been tested for raw water and test results has been compared with Indian standard parameters. Various results from SSF revealed the successful removal of suspended solids, natural and organic materials from raw water. Test results shows that designed SSF is highly efficient for improving the household water quality parameters. Designed SSF removes large number of impurities as compared to other filters and it is socially acceptable.

Turbidity curtains, also called as turbidity barriers and silt curtains, were designed to contain plumes of suspended solids in water bodies. The high concentration of suspended solids in the raw water impacts on the costs of its treatment. Water with higher turbidity requires more coagulants in water treatment and needs a sludge management. In order to reduce turbidity in the water intake, the present study used a central composite rotational design (CCRD) for a set of 2 in-line turbidity curtains in a laboratory hydraulic flume. Three factors were analyzed: the grammage of the first barrier, the grammage of the second barrier and the solids application rate. The experimental design was made of 18 experiments. Furthermore one blank test was performed. The analyses of variance revealed which factors were significant for each answer. The first curtain efficiency was related positively with the first grammage and negatively with the second curtain grammage. The second curtain efficiency was related positively with the second grammage and application load, and negatively related with the first grammage. The system retention mass was influenced positively by the application load.

This project evaluated pharmaceuticals and personal care products (PPCPs) concentrations in drinking water originating from Lake Erie. Raw and treated water samples were collected from the local water treatment plant in Erie, Pennsylvania over a 10 month period. Along with grab samples, long-term samples were collected using Polar Organic Chemical Integrative Samplers (POCIS). The samples were analyzed for 17 PPCPs (acetaminophen, ampicillin, atrazine, bisphenol-A, caffeine, carbamazepine, cimetidine, ciprofloxacin, digoxin, gemfibrozil, ibuprofen, metformin, naproxen, simazine, sulfamethoxazole, sulfathiazole, trimethoprim) in raw and treated drinking water. For grab samples, six of the 17 PPCPs were found at detectable levels in raw or treated drinking water including atrazine, bisphenol-A, caffeine, ibuprofen, metformin, and simazine. Detectable PPCP levels in treated water samples were usually lower than those in raw water. For long-term samples, an additional four PPCPs (ten total) were found at detectable levels including gemfibrozil, naproxen, sulfamethoxazole, and trimethoprim. Aqueous phase concentrations of PPCPs were estimated using sampling rates, deployment periods, and analytical results of POCIS samplers.

The design of Pre-sedimentation basins is based on design criteria including surface overflow rate and detention time. The previous studies differ in specifying the criteria values and, subsequently, it is difficult to choose the suitable ones according to raw water source characteristics. The aim of this study is to specify the design criteria values for pre-sedimentation basin treats the water of Shatt Al-Arab River. To satisfy this aim, experimental work was conducted including 51 plain sedimentation experiments and 37 particles size distribution analyses. The work results were used to determine the values of surface overflow rate and detention time in terms of actual and theoretical efficiencies of pre-sedimentation basin. The study results indicated that to use a pre-sedimentation basin in treating the water of Shatt Al-Arab River and the other rivers which have suspended solids with d50 values vary over the range (7.4-20.9) µm at efficiency exceeds 50%, the surface overflow rate must be less than 0.5 m/day and the detention time must be greater than 12.3 hr.

2-Methylisoborneol (2-MIB) is one of the most common taste and odor (T&O) compounds in waterbodies and causes complaints from drinking water consumers. This is a case study of two water treatment plants taking the raw water from Lake Tai, the third largest lake in China. The relationships between the 2-MIB concentration and algae density, light change and nutrients of the raw water for the most recent four years were comprehensively investigated. The yearly variation pattern of the 2-MIB concentration in the raw water is closely related to the algae cell density. Both values reached peaks in July or August with concentrations as high as ∼500 ng/L and ∼1000 × 104 count/L, respectively. For the diurnal 2-MIB variation, the concentrations increase from 5 to 6 am, reach a peak value at ∼12 p.m., and then gradually decrease and achieve the lowest value at night. These results further confirm that 2-MIB is highly related to algae cell activity (e.g., photosynthesis). In addition, 2-MIB exists both inside and outside algae cells (i.e., intracellular and extracellular or bound and dissolved 2-MIB, respectively), and the percentage of the extracellular/dissolved portion was as high as 60% during the study period. Conventional water treatment processes (usually referrings to coagulation sedimentation and sand filtration, CSF) in WTPs have extremely unstable 2-MIB removal efficiencies (from −20% to >95%), which is mainly related to the existing forms of 2-MIB. The intracellular/bound portion can be effectively removed by CSF, especially sand filtration, while advanced water treatment processes are required to remove the dissolved 2-MIB. An ozone-activated carbon process is recommended, and the 2-MIB removal rate can reach 100%. This research has great theoretical and engineering value for treating water containing T&O compounds.

Water resources provide multiple services, one of the most important the provision of drinking water, conventionally treated before public consumption as potable supplies. With increasing pressures from land use and climate change, there are advantages to be gained from considering raw water quality as a fundamental characteristic of the natural resource, and to anticipate emerging risks within the catchments rather than relying on treatment. This research proposes a large-scale, rapid risk screening of raw water quality based on catchment sensitivity to pressures as prerequisite to a more strategic inclusion of emerging risks in water resource and ecosystem management. Raw water quality observations from 154 surface water catchments in Scotland were investigated to determine the national baseline and to identify current pressures and underlying drivers. Patterns and spatial dependencies were investigated using principal component analysis, redundancy analysis, cluster analysis, and regression trees. These statistical approaches highlight the interaction between intrinsic catchment biophysical properties, land use and climate in characterising water quality risks and identify the focus for prioritising catchment interventions and risk-mitigation in the future. The emphasis on raw water quality will also support an ecosystem-based approach to increase catchment resilience, to ensure long-term supply of good quality drinking water while simultaneously creating wider benefits for society and the environment.

Rotavirus is one of the main waterborne causes of diarrhoea. Rotavirus type A is responsible for diarrhoea in infants and causes thousands of deaths annually around the world, especially in developing countries. Rotavirus is very small and is highly resistant to common disinfectants, so the World Health Organization (WHO) has chosen this virus as a reference pathogen in drinking water and has recommended a its 6-log removal by the conventional water treatment process to supply safe drinking water. We measured some physical and chemical characteristics of raw water at a water treatment plant in Tehran, Iran, including temperature, pH, total organic compound (TOC) concentration and initial turbidity, to determine their effect on rotavirus removal efficiency in various processes. We then measured rotavirus removal efficiency in clarified water and filtrate to determine their removal efficiency. Finally, we applied the WHO guideline and an empirical quantitative microbial risk assessment (QMRA) model to estimate probable health risk based on a residual number of rotavirus in finished water. We found that TOC concentration and water temperature are both effective on residual rotavirus in clarified water but they have no significant effect on the efficacy of filtration in rotavirus removal. Maximum rotavirus removal efficiency by clarification and filtration was 97.2% and 4.5% in April and January respectively. TOC and water temperature were shown to have a significant effect on clarification virus efficiency, so filtration performance was independent of these variables. The results showed that induced risk by residual rotavirus is in an acceptable range (99.99945% removal annually), and also showed that the critical process in virus removal is clarification that can be affected by raw water quality.

Brackish water (BW) desalination represents an untapped potential for augmenting water resources by the reliable technology of reverse osmosis (RO). There is a significant economic incentive to operate the process at the highest possible water recovery. A high recovery has the important advantage of reducing the amount of concentrate waste stream whose safe disposal is of significant environmental concerns. The degree of RO water recovery possible with a given raw water is dictated by the scaling problem. To overcome this hindrance, a variety of processes have been developed for conditioning the concentrate emanating from the primary RO unit for additional permeate production by a secondary RO unit. This paper provides a critical review of the treatment technologies that enable intensification of the water recovery in BWRO desalination by the intermediate concentrate demineralization techniques. The principles of each technique as well as its strength, weaknesses, technology readiness level, and economics are discussed. Extensive application of ICD technologies requires overcoming challenges such as lowering energy demand and total cost and reducing membrane scaling and use of chemicals.

Excessive fluoride content in groundwater can cause serious risks to human health, and sources of groundwater intended for human consumption should be treated to reduce fluoride concentrations down to acceptable levels. In the particular case of the island of Tenerife (Canary Islands, Spain), the water supply comes mainly from aquifers of volcanic origin with a high content of fluorides that make them unacceptable for human consumption without prior conditioning treatment. The treatments that generate a high rejection of water are not acceptable because water is a scarce natural resource of high value. An electrocoagulation process was investigated as a method to treat natural groundwater from volcanic soils containing a hazardously high fluoride content. The operating parameters of an electrocoagulation reactor model with parallel plate aluminum electrodes were optimized for batch and continuous flow operations. In the case of the batch operation, acidification of the water improved the removal efficiency of fluoride, which was the highest at pH 3. However, operation at the natural pH of the water achieved elimination efficiencies between 82 and 92%, depending on the applied current density. An optimum current density of 5 mA/cm2 was found in terms of maximum removal efficiency, and the kinetics of fluoride removal conformed to pseudo-second-order kinetics. In the continuous-flow operation, with the optimal residence time of 10 min and a separation of 0.5 cm between the electrodes, it was observed that the current density that would be applied would depend on the initial concentration of fluoride in the raw water. Thus, an initial fluoride concentration of 6.02 mg/L required a current density >7.5 mA/cm2 to comply with the legal guidelines in the product water, while for an initial concentration of 8.98 mg/L, the optimal current density was 10 mA/cm2. Under these operating conditions, the electrocoagulation process was able to reduce the fluoride concentration of natural groundwater to below 1.5 mg/L according to WHO guidelines with an operating cost between 0.20 and 0.26 €/m3 of treated water.

Due to rapid growth in the potable reuse industry, there is a need to better characterize the associated pathogen risks and degree of attenuation achieved by various treatment trains. It is also important to understand how emerging treatment frameworks compare to the historical practice of de facto reuse. As such, the goals of this study were to (1) evaluate the equivalency of indirect potable reuse (IPR) and direct potable reuse (DPR) systems; (2) compare alternative treatment trains; and (3) identify the design components and operational conditions that are most critical to minimizing public health risks. To this end, we developed a static quantitative microbial risk assessment (QMRA) for Cryptosporidium, norovirus, adenovirus, and Salmonella. Treatment process performance (including failure scenarios) and resultant public health risks were estimated using a Stella 10.1 system dynamics model. The combined annual risk of infection was lower in DPR systems with no surface water influence [median risk = 1.1 × 10−8 for ozone-based DPR and 3.9 × 10−6 for DPR with reverse osmosis (RO)] compared with IPR systems or DPR with raw water augmentation (median risk = 9.0 × 10−4 to 3.8 × 10−3). Although de facto reuse, planned IPR, and DPR with raw water augmentation exceeded the common 10−4 annual risk benchmark, the risks were generally dominated by the pathogen concentrations in the upstream surface water, thereby highlighting the importance of source water characterization in all drinking water systems. Moreover, the risk calculation for each system was often dominated by a particular pathogen (e.g., adenovirus with a maximum risk of 3.7 × 10−2 for RO-based DPR during a compound failure). Sensitivity analyses demonstrated that storage time and temperature were important for de facto reuse and during compound failures and that risks generally decreased with greater recycled water contributions (RWC) due to the robustness of advanced treatment and/or attenuation in the environmental buffer.

A new in-situ pre-enrichment system was developed for trace analysis of radioactive Cs in environmental water such as rivers, ponds, and seas, where the radioactive Cs is separated into suspended substances (SS) and dissolved substances (DS). The SS component was collected as the enrichment slurry by cross-flow filtration, thereby compact systems were realized. The DS component was collected in a small cartridge filled with a non-woven fiber with immobilized adsorbent nanoparticles. The recovery rate was estimated at around 95%. The size distribution of the SS and the concentration of radioactive Cs after enrichment were the same as that of the raw water before enrichment. The condensed SS can be used for other evaluations such as ignition loss. From the field test at a pond in the Fukushima-area, the Cs concentration of the SS was found to be 4–5 times higher than that of the sediment in the same pond. The organic content estimated by ignition loss was also three times higher.

Formulating effective management intervention measures for water supply systems requires investigation of potential long-term impacts. This study applies an integrated multiple regression, random forest regression, and quantitative microbial risk assessment (QMRA) modelling approach to assess the effect of climate-driven precipitation on pathogen infection risks in three drinking water treatment plants (WTPs) in Norway. Pathogen removal efficacies of treatment steps were calculated using process models. The results indicate that while the WTPs investigated generally meet the current water safety guidelines, risks of Norovirus and Cryptosporidium infection may be of concern in the future. The pathogen infections attributable to current projections of average precipitation in the study locations may be low. However, the pathogen increases in the drinking water sources due to the occurrence of extreme precipitation events in the catchments could substantially increase the risks of pathogen infections. In addition, without optimal operation of the UV disinfection steps in the WTPs, both the present and potential future infection risks could be high. Therefore, the QMRA models demonstrated the need for improved optimization of key treatment steps in the WTPs, as well as implementation of stringent regulations in protecting raw water sources in the country. The variety of models applied and the pathogen: E. coli used in the study introduce some uncertainties in the results, thus, management decisions that will be based on the results should consider these limitations. Nevertheless, the integration of predictive models with QMRA as applied in this study could be a useful method for climate impact assessment in the water supply industry. © 2019. This is the authors’ accepted and refereed manuscript to the article. Locked until 4.1.2021 due to copyright restrictions. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/

Calibrated adsorption-based passive samplers were used for time-integrative monitoring of microcystins (MCs) in three full-scale drinking water treatment plants (DWTPs) in the Czech Republic during two vegetation seasons (Jun-Nov), in parallel with traditional discrete sampling. MCs were detected in epilimnetic water samples at concentrations up to 14 mu g/L, but their levels in raw water in DWTPs were below 1 mu g/L WHO guideline value for drinking water. Conventional treatment technologies (coagulation/filtration) eliminated cyanobacteria and intracellular toxins but had a limited removal efficiency for extracellular toxins. MCs were regularly detected in final treated water, especially in DWTPs equipped only with the conventional treatment, but their concentrations were below the quantitation limit of discrete sampling (

Probabilistic lifetime cancer risks and non-cancer risks of trihalomethanes (THMs) through ingestion, dermal contact, and inhalation exposure in 88 drinking water treatment plants (WTPs) with raw waters from five water systems (WSs) in Jiangsu Province were analyzed and compared. Concentrations of THMs in finished water of study WTPs varied, ranging from 18.81 to 38.96 μg/L, which are lower than the maximum of 80 μg/L recommended by USEPA. The results of health risk assessment indicated that cancer risk as well as non-cancer risks of THMs in WTPs sourced from five water systems decreased in the order of WS3 > WS5 > WS2 > WS1 > WS4. The comparison among multiple exposure routes indicated that when non-boiled drinking water is consumed, ingestion has the highest exposure route, with exposure values greater than dermal contact and inhalation for WTPs with raw water from all five water systems. However, when drinking boiled water, dermal contact is the major risk source for WTPs with raw water from WS1 and WS2, instead of dermal contact, inhalation becomes the major risk source for WTPs with raw water from WS3, WS4, and WS5. In WTPs with raw water from water systems WS1, WS3, WS4, and WS5, dibromochloromethane (DBCM) in THMs has the highest contribution to cancer risk, while chloroform in THMs has the highest contribution to non-cancer risk. However, in WTPs with raw water from water system WS2, bromodichloromethane (BDCM) has the highest contribution to both cancer risk and non-cancer risk. The results also indicated that females are prone to cancer risk induced by THMs since Chinese people are accustomed to drinking boiled water. The results supply valuable information for health departments to put forward more specific and efficient policies to control water borne diseases.

Conventional coagulants, like aluminium sulphate and ferric chloride, are used in potable water treatment and involve non-sustainable mining and transformation of raw materials for their production with costly sludge disposal. Natural coagulants are mostly obtained from bacteria, fungi, animals and plants and are classified as polysaccharide, amino-polysaccharide, poly-phenols and proteins-based substances. Plant-based coagulants extracted from Moringa oleifera, Strychnos potatorum Linn, Plantago ovate, Trigonella foenum graecum and Opuntia ficus indica are potential substitutes to chemicals mostly based on bench-scale testing. These are organic polymers and polyelectrolytes that are classified as cationic, anionic and non-ionic coagulants. This paper provides a historical and contemporary review of plant-based coagulants, their notable milestones achieved, chemistry involved, as well as bench, pilot and full scale trials, highlighting the effects of plant-based coagulants on physico-bio-chemical properties of raw water. Commercialisation constrains are also included and discussed.

In the agriculture intensive eastern region of England, plant protection products are widely applied to protect crops such as wheat and oilseed rape from pests and diseases, thus creating a risk of reaching nearby water courses through surface runoff. The EU Drinking Water Directive sets a stringent limit of 0.1 μg/l and 0.5 μg/l for individual and total pesticides respectively in treated potable water. However, peak metaldehyde levels have been persistently detected in raw water and reducing them to these limits has proven challenging and costly, in particular when using conventional treatment. In line with the EU Water Framework Directive, a more suitable approach and one adopted by the local water company, Anglian Water Services Ltd., would require moving towards mitigating pollution at source, preferably through participative action with multiple stakeholders in the agricultural industry. Initial findings demonstrate the potential of product substitution for reducing metaldehyde levels in surface waters. Reviewing Anglian Water's “Slug it Out” trial, we discuss key learnings derived from their experiences and make recommendations about the potential of the catchment approach to address the wider pesticide challenge.

Tris (2-chloroethyl) phosphate (TCEP) is a typical phosphate flame retardant. Its potential adverse health effects have recently aroused concern. We investigated the seasonal variations of TCEP concentrations in the raw, finished and tap water samples from two drinking water treatment plants (DWTPs) in China, and evaluated the cytotoxicity and apoptosis/necrosis of organic extracts (OEs) in water samples. We enriched TCEP and OEs in water samples by solid-phase extraction method. The TCEP concentrations in water samples were determined by gas chromatography–mass spectrometry. Normal human liver cell line L02 was treated with OEs in the water samples, and then the cytotoxicity and apoptosis/necrosis were measured by 3-(4, 5-dimethyithiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay and flow cytometry, respectively. The results showed that cytotoxicities of OEs in raw water samples from both DWTPs in summer and winter were stronger than those in spring and autumn, cytotoxicity of OEs in finished and tap water samples from both DWTPs in summer and autumn were stronger than those in spring and winter. In all seasons, the maximal concentrations (100 mL water/mL cell culture) of OEs in the raw water samples from both DWTPs induced late apoptosis/necrosis. The reasons for seasonal variations of TCEP in water samples and potential toxic effects of other pollutants in the water samples need to be further investigated.

Water management subsystem (WMS) is a major component of the controlled ecological life support system (CELSS). For guaranteeing the water requirement of crop growth and crewmember's daily life, a WMS was established in a 4 person 180-day integrated experiment (carried out in Shenzhen, China, 2016) to maintain a closed cycle with a total water amount of ~23 m3. The design and operation of the WMS was summarized as follows: (1) Collection and allocation of condensate water. About 917 L/d condensate water (>98% was from plants' evapotranspiration) was collected, and ~866 L/d of which was reused as plant nutrient solution after ultraviolet (UV) disinfection, and 50.6 L/d was used as the raw water for the domestic water supply module (DWS). (2) Domestic water supply. The condensate water from the plant cabin was purified through the DWS, a modified membrane bioreactor (MBR) system, and then provided hygiene and potable water to 4 crewmembers with different water quality standards. (3) Wastewater recovery. 51.4 L/d wastewater from urination and personal hygiene were treated together via a biological wastewater treatment process to complete the conversion of nitrogen and organic matters, and then recycled to plant nutrient solution. (4) Nutrient solution recycling. In the overall water cycle process, the plant nutrient solution was continuously self-circulated and the water quality of which was maintained at a relatively stable level with total organic carbon of 20–30 mg/L and NH4+-N

The heterogeneity of dissolved organic matter (DOM) in natural and human impacted waters and the variety of drinking water treatment processes employed has made a mechanistic understanding of disinfection byproduct (DBP) formation challenging. In this study, we examined the formation of the regulated DBPs (Trichloromethanes, THM, and Haloacetic acids, HAA) during full-scale water treatment operations both with prechlorination treatment (normal operations for the drinking water plant) and without (altered operations); followed by coagulation, flocculation, filtration, and chlorination. The source water DOM concentration ranged 6.4 to 7.3 mg-C/L. DOM composition was moderately humic and degraded with a mix of microbial- and terrestrial-like characteristics. Removal of raw water prechlorination caused an average reduction in total THM and HAA concentrations of 52.7% and 40.0%, respectively, with the greater reduction noted for chlorinated-DBPs rather than brominated-DBPs. Prechlorination treatment resulted in a higher relative production of Cl3CH and BrCl2CH associated with aromatic, humic, and terrestrial-like DOM. Without prechlorination, the DBP pool had higher proportions of brominated-DBPs (Br3CH, Br2ClCH, Br2CHCOOH, BrClCHCOOH, and BrCH2COOH) associated with microbial-like, processed humic-like, and protein-like DOM. These observed patterns could not be explained by chloride demand and DOM concentration, indicating that DOM composition played an important role in DBP formation.

Demand for drinking water and wastewater services has increased drastically due to increased urbanization and population growth worldwide. The provision of these services entails several negative externalities including greenhouse gas emissions (GHGs). Conventional economic performance evaluation methods often ignore the negative externalities of production. Using a nonparametric approach, this paper analyzes the environmental efficiency of drinking water utilities, which incorporates GHGs into the evaluation as an undesirable output. A model based on the directional distance function was applied to drinking water and wastewater utilities in Australia. Findings indicate that the source of raw water, the level of wastewater treatment and production density have a statistically significant influence on the environmental efficiency of drinking water and wastewater utilities.

The study investigates the content of microplastic particles in freshwater and drinking water. Specifically, three water treatment plants (WTPs) supplied by different kinds of water bodies were selected and their raw and treated water was analysed for microplastics (MPs). Microplastics were found in all water samples and their average abundance ranged from 1473 ± 34 to 3605 ± 497 particles L−1 in raw water and from 338 ± 76 to 628 ± 28 particles L−1 in treated water, depending on the WTP. This study is one of very few that determine microplastics down to the size of 1 μm, while MPs smaller than 10 μm were the most plentiful in both raw and treated water samples, accounting for up to 95%. Further, MPs were divided into three categories according to their shape. Fragments clearly prevailed at two of the WTPs and fibres together with fragments predominated at one case. Despite 12 different materials forming the microplastics being identified, the majority of the MPs (>70%) comprised of PET (polyethylene terephthalate), PP (polypropylene) and PE (polyethylene). This study contributes to fill the knowledge gap in the field of emerging microplastic pollution of drinking water and water sources, which is of concern due to the potential exposure of microplastics to humans.

One of the United Nations Sustainable Development Goals is to provide access to safe and clean drinking water. However, treating raw water in facilities currently involves using a non-negligible amount of energy, and the fossil fuels used are both expensive and emit greenhouse gases when combusted. Previous studies have evaluated the energy performance of drinking water treatment plants by estimating the amount of energy consumed per volume of water. However, such studies have not accounted for differences between treatment technologies and have assumed a common standard water treatment technology. To overcome these limitations, this study employed metafrontier data envelopment analysis to evaluate and compare the energy performance of four types of treatment technologies. This approach integrates energy intensity with pollutant removal efficiency into a single, synthetic index to deliver an energy-efficiency score. A comparison of the four treatment technologies showed that facilities using rapid-gravity filtration and coagulation-flocculation processes provided the highest energy efficiencies. However, energy intensity and energy efficiency metrics delivered contradictory results, which thus illustrates the importance of including pollutant removal efficiency data in performance assessments. This study provides valuable information for policy-makers when planning and developing new drinking water treatment plants and for water utility managers when identifying energy reduction opportunities in plants.

The spatiotemporal presence of overall disinfection by-products (DBPs) in two full-scale drinking water supply systems (DWSSs) were investigated using quantification of total organic halogen (TOX). The relationships of TOX with water quality parameters (especially the most regulated DBPs, trihalomethanes (THMs)) were also evaluated. The TOX levels ranged between 2.6 and 70.3 μg Cl/L and between 46.6 and 205.9 μg Cl/L in raw water and distribution water, respectively. The TOX concentration in water increased by an average of nine times after water treatment and varied slightly during distribution, suggesting that TOX in drinking water was mainly formed during chlorination disinfection rather than distribution. No clear seasonality in TOX level was observed. Positive correlations were found between raw water dissolved organic carbon (DOC) with an increase in TOX in treated water and between DOC level with TOX content in distributed water, emphasizing a key role of organics in TOX formation. Chloroform (TCM) was the dominant THM, followed by bromodichloromethane (BDCM) in the drinking water, and the levels of the other two measured THMs (dibromochloromethane and bromoform) were negligible. THM2 (sum of TCM and BDCM) made up average of 18% of the TOX, and was weakly correlated with TOX content (rs = 0.321; P

Microplastics (MPs) are the emerging pollutants in the fresh water and have been found in the drinking water. Drinking water treatment plant (DWTP) is an important barrier to ensure the safety and quality of drinking water, so their effectiveness in removing MPs needs to be evaluated and optimized. In this paper, the abundance, characteristics and removal performance of 5 μm-5 mm granular MPs and 100 μm-5 mm fibrous MPs in the effluent of each water treatment unit in a DWTP in China were analyzed. The results show that only 80.96% of MPs ≤ 20 μm, accounting for more than 98% in the raw water, could be removed in the DWTP, while over 99% of the removal efficiency could be achieved for MPs > 20 μm. Coagulation-sedimentation and micro-flocculation combined with sand filtration couldn't effectively remove the granular MPs ≤ 20 μm (42.8% and 25.8%, respectively), but biological activated carbon (BAC) filtration was prone to remove this part (63.8%). Significant increases of granular MPs ≤ 20 μm were observed in the effluents of biological treatment (+149.6%) and ozonation (+13.8%). According to the variation in separate MPs' size distribution, the increases in MPs were attributed to the fragmentation of MPs, on which ozonation showed a remarkable effect. The ozonation might accelerate the aging and embrittlement of MPs, and then external stresses could further break them into smaller pieces, which eventually lead to an increase in MPs. To deal with the stubborn part and fragmentation of MPs in water, the removal ability of DWTP for MPs ≤ 20 μm needs to be improved. This study provides a detailed proof for the fate of MPs in the DWTP, and the results indicate that the fragmentation of MPs and the removal rate of MPs ≤ 20 μm should draw more attention in the DWTP.

Textile dyeing industries are utilizing large quantity of raw water for the processing at dyeing and finishing units. At the same time, there generate huge amount of wastewater from different processes in the textile industry. Many of textile industries in India are using variety of synthetic dyes for the processing purpose. These dyes are very complex in nature. Many dyes contain organic compounds with functional groups, carboxylic (–COOH), amine (–NH2) and azo (–N=N–). Wastewater generating from textile industry is also found to be in variety of colours along with very high COD and BOD values. Present study deals with the treatment of textile dyeing effluent with aluminium electrodes in electrochemical reactor. Experiments were carried out at different pH range (4-10) and current density 53 mA/cm2. Maximum COD and Colour removal was found 95 % and 92 % respectively at optimum pH at the cost of 13.3 Wh/dm3. Electro-coagulation was found suitable for the treatment of textile dyeing effluent.

Pharmaceuticals (a class of emerging contaminants) are continuously introduced into effluent-receiving surface waters due to their incomplete removal within wastewater treatment plants (WWTPs). This work investigated the presence and distribution of eight commonly used human pharmaceuticals in the River Dee (Scotland, UK), a Scottish Environment Protection Agency priority catchment that is a conservation site and important raw water source. Grab sampling and passive sampling (Polar Organic Chemical Integrative Sampler, POCIS) was performed over 12 months, targeting: paracetamol, ibuprofen, and diclofenac (analgesics/anti-inflammatories); clarithromycin and trimethoprim (antibiotics); carbamazepine and fluoxetine (psychoactive drugs); and 17α-ethynylestradiol (estrogen hormone). Sampling sites spanned from the river's rural source to the heavily urbanised estuary into the North Sea. Ibuprofen (ranging 0.8-697 ng/L), paracetamol (ranging 4-658 ng/L), trimethoprim (ranging 3-505 ng/L), diclofenac (ranging 2-324 ng/L) and carbamazepine (ranging 1-222 ng/L) were consistently detected at the highest concentrations through grab sampling, with concentrations generally increasing down river with increasing urbanisation. However, POCIS revealed trace contamination of most compounds throughout the river (commonly0.5 ng/L), indicating pollution may be related to diffuse sources. Analysis of river flows revealed that low flow and warm seasons corresponded to statistically significantly higher concentrations of diclofenac and carbamazepine, two compounds of environmental and regulatory concern. Below the largest WWTP, annual average fluxes ranged 0.1 kg/yr (clarithromycin) to 143.8 kg/yr (paracetamol), with 226.2 kg/yr for total target compounds. It was estimated that this source contributed70% of the total mass loads (dissolved phase) of the target compounds in the river. As the River Dee is an important raw water source and conservation site, additional catchment monitoring is warranted to safeguard water quality and assess environmental risk of emerging contaminants, particularly in relation to unusual weather patterns, climate change and population growth.

Sulfonamides (SAs) and sul antibiotic resistance genes (ARGs) have been extensively detected in drinking water sources and warrant further studies on the removal of them in different drinking water treatment processes (DWTPs). The prevalence of 13 SAs, sul1, sul2 and class I integrase gene intI1 in conventional and advanced processes was investigated using HPLC-MS/MS and real-time quantitative PCR (qPCR), respectively. The most abundant SA was sulfamethoxazole, with the maximum concentration of 67.27 ng/L. High concentration of sulfamethoxazole was also measured in finished water in both conventional (22.05 ng/L) and advanced (11.24 ng/L) processes. Overall, the removal efficiency of advanced process for each SA was higher than that of conventional process, except for sulfameter. The absolute concentrations of sul1, sul2 and intI1 in raw water ranged from 1.8 × 103 to 2.4 × 105 gene abundance/mL. After treatment, the residual sul ARGs and intI1 in finished water still remained at 102 - 104 gene abundance/mL. Conventional treatment units, including flocculation/sedimentation/sand filtration, played a more important role in removing sul1, sul2 and intI1 than oxidation (chlorination or ozonation) and granular activated carbon filtration treatments. Based on this work, more investigations are needed to help improve the removal of both antibiotics and ARGs in DWTPs.

The presence of emerging pollutants in the aquatic environment in relatively small concentrations and the fact that they cannot be removed by conventional water/wastewater treatment processes bring new challenges in terms of adequate selection of technologies from the technical, economical and environmental points of view. Generally, literature discusses emerging pollutants’ removal at significant concentrations (such as those in wastewater), while few studies consider their low concentrations occurring in raw water. This study presents a comprehensive review of the research efforts related to the occurrence, fate, health effects and impacts of emerging pollutants on advanced drinking water treatment and the environmental performance evaluation of different technological options, with a focus on pilot and full-scale installations. All presented case studies consider pollutants removed, process conditions and removal efficiencies, thus making possible comparisons between membrane processes, advanced oxidation processes and adsorption on activated carbon and other materials. The study is completed by an analysis of the environmental assessment instruments (life cycle assessment, carbon, water footprints, other type of assessments) that may be used for selecting sustainable advanced drinking water treatment processes able to remove emerging pollutants. This paper critically reviews the main research topics concerning emerging pollutants: classification, legislative framework, up-to-date removal processes and their environmental performances assessment, to offer a comprehensive analysis of the strategic issues that may constitute future research directions for sustainable water supply.

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Because of the persistence and solubility of neonicotinoid insecticides (NNIs), there is concern that these compounds may contaminate sources of drinking water. The objective of this project was to evaluate the distribution of NNIs in raw and treated drinking water from selected municipalities that draw their water from the lower Great Lakes in areas of southern Ontario, Canada where there is high intensity agriculture. Sites were monitored using Polar Organic Chemical Integrative Samplers (POCIS) and by collecting grab samples at six drinking water treatment plants. Thiamethoxam, clothianidin and imidacloprid were detected in both POCIS and grab samples of raw water. The frequency of detection of NNIs was much lower in treated drinking water, but some compounds were still detected at estimated concentrations in the low ng L−1 range. Thiamethoxam was detected in one grab sample of raw drinking water at a mean concentration of 0.28 μg L−1, which is above the guidelines for drinking water recommended in some jurisdictions, including the European Union directive on pesticide levels

As drinking water supply systems plan for sustainable management practices, impacts from future water quality and climate changes are a major concern. This study aims to understand the intraannual changes of energy consumption for water treatment, investigate the relative importance of water quality and climate indicators on energy consumption for water treatment, and predict the effects of climate change on the embodied energy of treated, potable water at two municipal drinking water systems located in the northeast and southeast US. To achieve this goal, a life cycle assessment was first performed to quantify the monthly energy consumption in the two drinking water systems. Regression and relative importance analyses were then performed between climate indicators, raw water quality indicators, and chemical and energy usages in the treatment processes to determine their correlations. These relationships were then used to project changes in embodied energy associated with the plants' processes, and the results were compared between the two regions. The projections of the southeastern US water plant were for an increase in energy demand resulted from an increase of treatment chemical usages. The northeastern US plant was projected to decrease its energy demand due to a reduced demand for heating the plant's infrastructure. The findings indicate that geographic location and treatment process may determine the way climate change affects drinking water systems.

Presently, concentrations of fecal indicator bacteria (FIB) in raw water sources are not known before water undergoes treatment, since analysis takes approximately 24h to produce results. Using data on water quality and environmental variables, models can be used to predict real time concentrations of FIB in raw water. This study evaluates the potentials of zero-inflated regression models (ZI), Random Forest regression model (RF) and adaptive neuro-fuzzy inference system (ANFIS) to predict the concentration of FIB in the raw water source of a water treatment plant in Norway. The ZI, RF and ANFIS faecal indicator bacteria predictive models were built using physico-chemical (pH, temperature, electrical conductivity, turbidity, color, and alkalinity) and catchment precipitation data from 2009 to 2015. The study revealed that pH, temperature, turbidity, and electrical conductivity in the raw water were the most significant factors associated with the concentration of FIB in the raw water source. Compared to the other models, the ANFIS model was superior (Mean Square Error=39.49, 0.35, 0.09, 0.23CFU/100ml respectively for coliform bacteria, E. coli, Intestinal enterococci and Clostridium perfringens) in predicting the variations of FIB in the raw water during model testing. However, the model was not capable of predicting low counts of FIB during both training and testing stages of the models. The ZI and RF models were more consistent when applied to testing data, and they predicted FIB concentrations that characterized the observed FIB concentrations. While these models might need further improvement, results of this study indicate that ZI and RF regression models have high prospects as tools for the real-time prediction of FIB in raw water sources for proactive microbial risk management in water treatment plants.

We assessed the utility of online fluorescence spectroscopy for the real-time evaluation of the microbial quality of untreated drinking water. Online fluorimeters were installed on the raw water intake at four groundwater-derived UK public water supplies alongside existing turbidity sensors that are used to forewarn of the presence of microbial contamination in the water industry. The fluorimeters targeted fluorescent dissolved organic matter (DOM) peaks at excitation/emission wavelengths of 280/365 nm (tryptophan-like fluorescence, TLF) and 280/450 nm (humic-like fluorescence, HLF). Discrete samples were collected for Escherichia coli, total bacterial cell counts by flow cytometry, and laboratory-based fluorescence and absorbance. Both TLF and HLF were strongly correlated with E. coli (ρ = 0.71–0.77) and total bacterial cell concentrations (ρ = 0.73–0.76), whereas the correlations between turbidity and E. coli (ρ = 0.48) and total bacterial cell counts (ρ = 0.40) were much weaker. No clear TLF peak was observed at the sites and all apparent TLF was considered to be optical bleed-through from the neighbouring HLF peak. Therefore, a HLF fluorimeter alone would be sufficient to evaluate the microbial water quality at these sources. Fluorescent DOM was also influenced by site operations such as pump start-up and the precipitation of cations on the sensor windows. Online fluorescent DOM sensors are a better indicator of the microbial quality of untreated drinking water than turbidity and they have wide-ranging potential applications within the water industry.

This paper presents the work aiming to validate the practical feasibility of ferrate(VI) used as an alternative to the existing coagulant (e.g., ferric chloride/sulphate) for both drinking water and domestic sewage treatment via series of pilot plant trials. For drinking water treatment, a ferrate(VI) dose of 0.1 mg/L can achieve 93% and 97% particle removal (in terms of particle counting) after the filtration for raw water and for the ozonized water, respectively, which is satisfied to the treated water quality requirement for the particles’ removal. Moreover, ferrate(VI) can remove 10% metformin, benzotriazole and acesulfam from raw water but FeCl3 with ozonation can’t. When treating domestic sewage at pilot scale trials, ferrate(VI) demonstrated encouraging performance as well, at a very lower dose range, 0.1–0.2 mg Fe/L, ferrate(VI) achieved better performance in comparison with high dosed ferric sulphate. This will reduce chemical demand and sludge production and therefore results in a low operating cost and generates substantial cost saving in treating sewage. Keywords: BOD removal, Coagulation, COD removal, Drinking water treatment, Ferrate(VI), Micro pollutant reduction, Particle removal, Phosphorous removal, Sewage treatment

The most common desalination technology is based on reverse osmosis, which uses semi-permeable membranes and pressures from 5.5 MPa to 6.8 MPa in order to overcome the osmotic pressure. The lowest achievable energy consumption of RO is 2 kWh/m3. The other viable methods of desalination include membrane distillation and pervaporation. Each of these techniques has certain advantages and disadvantages but in terms of energy consumption pervaporation seems particularly promising. Over the past few years, desalination performed with the help of pervaporation has been widely investigated. In this study, desalination experiments were carried out with a commercial membrane. The salt concentration and the feed solution temperature were varied between 0.8% and 7.0% and between 40 °C and 70 °C, respectively. The experiments helped determine the desalinated water flux and the salt rejection factor. In addition, differences in enthalpy and Gibbs free energy, representing the theoretical energy consumption, were estimated in the raw water/feed and the feed/permeate systems. For the purpose of comparing the energy consumption, three desalination techniques were considered: RO, PV and MD.

To assess the potential of pepper mild mottle virus (PMMoV) as a viral process indicator, its reduction through coagulation–sedimentation (CS) and rapid sand filtration (RSF) were compared with those of Escherichia coli, previously used viral indicators, and norovirus genotype II (NoV GII; enteric virus reference pathogen) in a bench-scale experiment. PMMoV log10 reductions in CS (1.96 ± 0.30) and RSF (0.26 ± 0.38) were similar to those of NoV GII (1.86 ± 0.61 and 0.28 ± 0.46). PMMoV, the most abundant viruses in the raw water, was also determined during CS, RSF, and advanced treatment processes at two full-scale drinking water treatment plants under strict turbidity management over a 13-month period. PMMoV was concentrated from large-volume water samples (10–614 L) and quantified by Taqman-based quantitative polymerase chain reaction. The PMMoV log10 reduction in CS (2.38 ± 0.74, n = 13 and 2.63 ± 0.76, n = 10 each for Plant A and B) and in ozonation (1.91 ± 1.18, n = 5, Plant A) greatly contributed to the overall log10 reduction. Our results suggest that PMMoV can act as a useful treatment process indicator of enteric viruses and can be used to monitor the log10 reduction of individual treatment processes at drinking water treatment plants due to its high and consistent copy numbers in source water.

The aim of this study was to assess and compare the knowledge of Polish and Thai consumers regarding the causes of food poisoning and hygienic practices during the preparation of food at home. A questionnaire was prepared on the basis of Codex Alimentarius guidelines. It consisted of 15 questions related to consumers' knowledge of food poisoning causes, and 20 questions related to the consumers' food hygiene practice during the preparation of meals at home. Six hundred questionnaires were collected, 300 in Poland and 300 in Thailand. The results were subjected to statistical analysis. In Thailand, consumers showed significantly lower levels of food hygiene knowledge than in Poland. However, both Polish and Thai consumers had incomplete knowledge of the causes of food poisoning and, in many cases, their food hygiene practice during food preparation and consumption was inaccurate. None of the consumers responded correctly to all the questions concerning food hygiene knowledge. In the case of food hygiene practice, nearly total correct responses were noted only in the cases of washing hands after using the toilet, and the risk of drinking raw water from open air lakes and reservoirs. Some other elements of food hygiene practice were incorrectly stated in both countries, e.g. food defrosting, storage of cooked food at room temperature, and hand washing after handling raw, unwashed foods. Further research on consumers' food hygiene knowledge and practice should be conducted, and better food safety education should be organised independently of country of origin, education level and age. The results of this study could play an important role in the prevention of food poisoning by indicating which areas of consumers’ food hygiene knowledge and food hygiene practice during food preparation at home should be strengthened by educational activities.

Because it promotes efficient gas solubility, microbubble aeration has been widely used in ozonation of water systems. In conventional ozone treatment, disinfection by-products (DBPs) are a significant concern during subsequent chlorination, especially when raw water contains bromide. However, the effect of microbubbles ozonation on the formation of DBPs is not well characterized. In this study, we investigated the formation of DBPs during chlorination of bromide-containing water from Tai Lake after microbubble ozonation, and compared this to conventional bubbling. The results suggest that more bromate and bromo-organic DBP precursors were produced after microbubble ozonation, which creates a challenge to the practical implementation of microbubble ozonation in water treatment. Since bromate is the main DBP of concern in the presence of bromide during ozonation, we also explored the effect of natural organic matter and hydroxyl radicals on bromate formation. Finally, we found that the addition of ammonia reduced bromate formation during microbubble ozonation to levels even lower than with conventional bubble ozonation.

The occurrence of microplastics (MPs) in water intended for human consumption, including water supplied by drinking water treatment plants (DWTPs), has raised considerable attention. DWTPs appear to be capable of removing some of the MPs present in raw water; however, little is known about the efficiency of distinct treatment processes for MP elimination. This study investigated the coagulation of model MPs, i.e., polyvinyl chloride particles

The tailing storage facility is the largest water sink in most mines. An incorrect management of water content in mine tailings can become a threat to their stability, and consequently, their environmental safety. Also, water reuse and recycling are plausible options to mining companies for reasons pertaining to water scarcity. Dewatering technologies for tailings, desalination and water transport are energy intensive. Proper handling of mine tailings and water supply management can considerably improve the water-energy nexus. This article evaluates the water-energy nexus in copper mining companies using a water reduction model focused on mine tailing facilities and water supply to the mine site to find the trade-offs between water and energy. The originality of this work consists in the application of a real options approach, enabling to increase the flexibility of decision-making thanks to quantitative analysis. This approach deploys the Monte Carlo simulation to perform sensitivity and uncertainty analysis to evaluate every cost component of water management strategy. Results show that if seawater is the primary source of raw water to the mining plant, water transport represents the largest cost due to the use of energy. So, improving the reuse of water by using dewatering technologies will improve the water-energy nexus, by improving energy consumption. Even though the costs of these technologies are elevated because they are energy-intensive, reduction of water use requirements in the mine will reduce the cost of its treatment and transport.

The maximal recovery ratio of brackish water RO desalination plants located on the coastline can be significantly increased by exchanging Ca2+ with Mg2+ and Na+ ions in the raw water by passing the water through a cationic ion-exchange (CIX) resin which is thereafter regenerated with seawater. The concept allows also enriching the product water with Mg2+, at no additional cost. The Ca2+ fraction (equivalent-based) attached to the CIX resin at equilibrium with seawater was merely ~10% of its total capacity, much lower than Na+ (59%) and Mg2+ (28%). The process was simulated on the Sabha-Eilat BWRO plant (Israel) water with the goal of reducing [Ca2+] from ~850 to ~450 mg/L using a breakthrough/seawater-regeneration sequence. The goal was met by applying a 60 bed-volume (BV) breakthrough-step followed by 20-BV seawater regeneration (HRT = 6 min). ~2% of the CIX-mended water bypassed the RO step to provide 10 mg Mg/L in the product water. Simulating the maximal recovery ratio showed that it could be raised to 89.2%. A general design and cost-analysis revealed that the cost of each additional m3 of desalinated water produced by the new method was ~$0.23, ~14% more water is produced and retentate production is ~50% lower.

Water produced from municipal utilities accounts for nearly 10% of the sum water demand in China. The municipal water cycle that integrates processes of urban water supply, water use, sewage treatment, and water reclamation has been assessed for 655 cities across nine drainage areas in mainland China in 2012. These cities in total extracted 55km3 raw water for municipal use from surface waterbodies and ground aquifers, approximate to the countrywide freshwater extraction of Russia or Italy. After purification and transmission, 45km3 water was distributed to industrial, service, and domestic users. 36km3 of post-use sewage was collected and environmentally safely treated; merely 3.2km3 of the treated water was reclaimed. Driven by increasing urbanization, the municipal water demand in cities of China may grow 70% by 2030. The Hai River and the Huai River basins, which harbor 137 cities and occupy a majority of the densely populated North China Plain, are most exposed to physical water scarcity. The municipal water abstraction in these cities can remain constant by promoting demand-side and process conservation in the next two decades. Interbasin transfer and unconventional sources will provide municipal water double than the cities' need. Whereas the urban water security can be technically enhanced, the challenges are to better improve water use efficiency and mitigate economic and environmental costs of the municipal system.

Removal of natural organic matter (NOM) is increasingly important in production and distribution of drinking water complying with health and aesthetic guidelines. The impact of treatment is often investigated using the resulting dissolved organic carbon (DOC) concentration and trihalomethane formation potential. Water treatment processes of ferric and alum coagulation with and without pre-oxidation by ozone and permanganate were scanned for their ability to treat synthetic raw water from peat extract. To compare the efficiency of the treatment methods the dissolved organic carbon (DOC) concentration and chlorine decay and trihalomethane (THM) formation tests — the important parameters needed in practice were used. A high level of DOC removal (>80%) was achieved with all the treatments. A significant difference was observed in chlorine decay rates and THM production. Pre-oxidation with 2 mg/L of O3 and coagulation with 45 mg/L of ferric sulphate produced the most chlorine stable water followed by water treated with 80 mg/L of ferric sulphate. Chlorine decay test was found to be a more sensitive indicator of a successful treatment than DOC. The optimisation of the ozone dose is likely to identify the best water quality and chemical cost combination which is not likely achievable by the coagulation alone.

This research assessed water–energy nexus (WEN) efficiency in Chile's drinking water treatment plants by integrating the life cycle concept and exergy analysis principles. The cumulative exergy consumption (CExC) attributed to freshwater and the energy required by drinking water facilities during the whole life cycle were determined. Water-related indicators, such as the water stress index (WSI) and blue water footprint (BWF), differentiated by region, were used to highlight the critical role of water resources within the nexus. The CExC depicted significant differences between regions (10–30 MJex/m3), depending on the quality of raw water sources, pumping, and drinking water treatment (DWT) configurations. The WSI and the BWF varied spatially across the country due to climatic variability. Regions with a higher WSI (0.4–1) also implied higher CExC. This pattern can be justified by low water availability and poor water quality, which, at the same time, implied more energy-intensive technologies. Improving water and energy efficiency were identified as critical strategies for reducing the water and energy demand in the urban DWT systems.

Forest cover improves surface water quality by minimizing soil erosion, reducing sediment in water and trapping or filtering water pollutants in forest litter. Because the amount of chemicals needed to produce potable water depends on the quality of intake water, upstream forest cover protection may help reduce the extent and cost of water treatment downstream. However, many other drivers exist for the cost of water treatment, so the magnitude and relevance of the influence of forest cover on water treatment cost is an empirical question. We analyze the impact of forest cover on the quality of raw water and the extent of water treatment required at the water treatment plants in Costa Rica, using monthly panel data in 2008-2014 from the drinking water treatment plants managed by the national public utility. We find that forest cover change during the study period statistically significantly affected the chemical use by water treatment plants. In economic terms, the estimated value of water purification service provided by forests is USD 9.5 per hectare per year. Depending on the discount rate, this results in a net present value of water purification service ranging between USD 315.4 and USD 113.9 per hectare. The results indicate that the economic value of the water purification service of forest is 1.7% of the value for recreational services; between 3.2% and 1.1% relative to the value of forest carbon sequestration typical in Costa Rica, depending on the discount rate; and around 13% of the payments for watershed protection program by the National Forest Financing Fund. The results also show that the marginal contribution of forest, on a per hectare basis, on water quality becomes larger as the size of catchment decreases.