Desalinated versus recycled water: public perceptions and profiles of the accepters

Chitosan-based aerogels: A new paradigm of advanced green materials for remediation of contaminated water

Chitosan (CS) aerogels are highly porous (∼99 %), exhibit ultralow density, and are excellent sorbents for removing ionic pollutants and oils/organic solvents from water. Their abundant hydroxyl and amino groups facilitate the adsorption of ionic pollutants through electrostatic interaction, complexation and chelation mechanisms. Selection of suitable surface wettability is the way to separate oils/organic solvents from water. This review summarizes the most recent developments in improving the adsorption performance, mechanical strength and regeneration of CS aerogels. The structure of the paper follows the extraction of chitosan, preparation and sorption characteristics of CS aerogels for heavy metal ions, organic dyes, and oils/organic solvents, sequentially. A detailed analysis of the parameters that influence the adsorption/absorption performance of CS aerogels is carried out and their effective control for improving the performance is suggested. The analysis of research outcomes of the recently published data came up with some interesting facts that the unidirectional pore structure and characteristics of the functional group of the aerogel and pH of the adsorbate have led to the enhanced adsorption performance of the CS aerogel. Finally, the excerpts of the literature survey highlighting the difficulties and potential of CS aerogels for water remediation are proposed.

A review of limitations and potentials of desalination as a sustainable source of water

For centuries, desalination, in one way or another, has helped alleviate water scarcity. Over time, desalination has gone through an evolutionary process influenced largely by available contemporary technology. This improvement, for the most part, was reflected in the energy efficiency and, in turn, in terms of the cost-effectiveness of this practice. Thanks to such advancements, by the 1960s, the desalination industry experienced notable exponential growth, becoming a formidable option to supplement conventional water resources with a reliable non-conventional resource. That said, often, there are pressing associated issues, most notably environmental, socioeconomic, health, and relatively recently, agronomic concerns. Such reservations raise the question of whether desalination is indeed a sustainable solution to current water supply problems. This is exceptionally important to understand in light of the looming water and food crises. This paper, thus, tends to review these potential issues from the sustainability perspective. It is concluded that the aforementioned issues are indeed major concerns, but they can be mitigated by actions that consider the local context. These may be either prophylactic, proactive measures that require careful planning to tailor the situation to best fit a given region or reactive measures such as incorporating pre- (e.g., removing particles, debris, microorganisms, suspended solids, and silt from the intake water prior to the desalination process) and post-treatments (e.g., reintroducing calcium and magnesium ions to water to enhance its quality for irrigation purposes) to target specific shortcomings of desalination.

Current challenges and future perspectives for the full circular economy of water in European countries

This paper reviews the current problems and prospects to overcome circular water economy management challenges in European countries. The geopolitical paradigm of water, the water economy, water innovation, water management and regulation in Europe, environmental and safety concerns at water reuse, and technological solutions for water recovery are all covered in this review, which has been prepared in the frame of the COST ACTION (CA, 20133) FULLRECO4US, Working Group (WG) 4. With a Circular Economy approach to water recycling and recovery based on this COST Action, this review paper aims to develop novel, futuristic solutions to overcome the difficulties that the European Union (EU) is currently facing. The detailed review of the current environmental barriers and upcoming difficulties for water reuse in Europe with a Circular Economy vision is another distinctive aspect of this study. It is observed that the biggest challenge in using and recycling water from wastewater treatment plants is dealing with technical, social, political, and economic issues. For instance, geographical differences significantly affect technological problems, and it is effective in terms of social acceptance of the reuse of treated water. Local governmental organizations should support and encourage initiatives to expand water reuse, particularly for agricultural and industrial uses across all of Europe. It should not also be disregarded that the latest hydro politics approach to water management will actively contribute to addressing the issues associated with water scarcity.

Integrating water science, economics, and policy for future climate adaptation

Water science, water economics, and water policy issues continue to rise in importance internationally as elevated population, income growth, and climate change magnify scarcity, shortages, and injustices in water access. Based on the unique physical, institutional, and economic characteristics of water, this work's first contribution is to characterize a road forward for research innovations that enable better integration of water science, water economics, and water policy. Meeting water's sustainable development and justice goals calls for several research innovations that humanity awaits. The advances called for in this work include deep uncertainty management, red team reviews, innovative water rights design, accelerating SDG achievement, valuing water infrastructure, valuing natural water retention, incentivizing water conservation, improving financial performance of rural water systems, water network modularization, non-price scarcity signals, optimization model calibration, remote sensing, transboundary benefit sharing, optimal growth, and water valuation. The work's second contribution is to present a prototype scalable basin scale hydroeconomic analysis (HEA) as a framework for integrating these above innovations when they occur. Results of the HEA show that losses from a 50% shortage in the basin's surface water supply can continue to protect 93% of total economic benefits across economic sectors if an efficient water trading system is established to move water from lower to higher valued uses when shortages occur. The work concludes by noting that great advances remain needed for better and longer lives.

Wastewater reclamation trends in Thailand

Thailand constantly faces the problem of water scarcity, resulting from an imbalance between available water supply and increasing water demand for economic and community expansion, as well as climate change. To address this shortage, wastewater reclamation is being planned and implemented throughout the country, along with a 20-year, long-term integrated water resource management plan. Significant opportunities from municipal wastewater treatment plants (WWTPs) are dependent on the following factors: the establishment of a reuse water framework and a tangible target for treated wastewater set by local government authorities; widespread recognition and adaptation of wastewater reuse measures in the agriculture, industry, tourism and service sectors regarding climate change and water stress; and the implementation of joint investment water reuse projects between private and government agencies. However, wastewater reclamation faces some significant challenges, specifically: the limitations of regulation and monitoring for specific reuse purposes; a lack of public confidence in the water quality; the limited commercial development of reclaimed wastewater research; and difficulties in self-sustaining business models through adapting circular economy principles. This study aims to provide an overview of the wastewater reclamation, present research trends, currently operating WWTPs as well as opportunities and challenges to speed up water reuse activities in Thailand.

Root system response to salt stress in grapevines (Vitis spp.): A link between root structure and salt exclusion

Accessing freshwater resources for agriculture becomes more complex due to increasing demands and declining water quality. Alternative water sources, such as saline water, require ad hoc solutions. Therefore, understanding roots' response to saline water is crucial for future agriculture. We examined the response of three grapevine rootstocks (Paulsen 1103, Richter 110 and SO4) to salt stress. The rootstocks were subjected to two salinity treatments: 10 mM and 30 mM NaCl (EC = 2 and 4 ds/m, respectively). Root and shoot samples were taken at the end of the experiment for morphologic and ionomic analyses. The specific root area (SRA) increased in response to salinity for all three rootstocks due to root tissue density and average root diameter reductions. Salinity also led to increased root Na⁺ and Cl^- contents and reduced root K⁺/Na⁺ ratio, parallel to increased leaf Cl^- but not Na⁺ contents. SO4 showed improved chloride and sodium exclusion, concomitant with its highest SRA, resulting from the increase in its thin roots' contribution to the total root system surface area. We suggest that enhanced SRA combined with decreased root tissue density and diameter may improve grapevines' salt exclusion by less salt uptake from the soil.

Recycled water acceptance: Data from two Spanish regions with opposite levels of scarcity

The dataset presented in this paper were collected for testing a perceptive-axiological model of recycled water acceptance for low and high contact uses. Participants were selected by proportional random sampling by sex and age the two Spanish communities with the most extreme values of water stress (Galicia, the rainiest region and Murcia, the driest). Data were collected by a company specialized in market research using an online survey housed on Qualtrics. Participants who matched the specified profile were contacted by email. The company compensated them financially. The final sample size consisted of 726 valid responses. The survey collected data on a variety of variables related to three conceptual dimensions: the diagnosis of the environmental situation, the axiological influence and the public perceptions regarding recycled water. The survey also collected demographic data from respondents. The survey was designed and reviewed by four experts in social psychology and two experts in methodology. The dataset featured in this article provides the raw survey data plus sociodemographic distribution, survey items, and other statistical data. This is the first and most comprehensive set of comparative data known to the authors on public acceptance of water reuse for high and low contact uses comparing regions with and without water scarcity. The authors have published an open access paper based on this data set, which are linked to this paper. Water industry professionals, policymakers, researchers and other stakeholders aiming to implement wastewater reuse systems in society may be interested in using the data as a point of comparison for their own study on public acceptance of water reuse or examining the data for relationships not yet explored in the literature.

Analysis on the Knowledge Evolution Path of Public Acceptance of Reclaimed Water Research

Reclaimed water is an important component of available water resources, and public acceptance of reclaimed water is a key factor influencing the implementation of reclaimed water reuse projects. For this reason, it has received attention from different scholars in the international community. Based on the literature data on public acceptance of reclaimed water, this study analyzes the development status of research results and explores the knowledge evolution path with the help of bibliometric methods. Our results show that the field of research on public acceptance of reclaimed water began to grow rapidly after 1990, and identify influential countries, institutions, authors, and journals in the field. In addition, “water quality”, “public health”, and “irrigation” are themes that run throughout the research, and “sustainable development” and “potable reuse” are the emerging research hotspots. As research progresses, the scope of research on reclaimed water reuse and its influencing factors continues to expand, and reclaimed water management policies and standards continue to improve. In the future, in order to improve public acceptance, finding how to improve the public’s risk perception and trust in reclaimed water will become a central research focus.

The Gap between Willingness and Behavior: The Use of Recycled Water for Toilet Flushing in Beijing, China

Promoting the use of recycled water is an effective way to solve the problem of urban water shortage. In order to promote the utilization of recycled water, this study identified the influential factors determining the differences between willingness and behavior to use recycled water for toilet flushing. Binary logistic regression models of willingness and behavior were analyzed and the data came from 1195 Beijing residents in communities where recycled water was available for toilet flushing. The results are as follows: First, the proportion of those willing to use recycled water (92%) was significantly higher than those who actually did so (35.2%); thus, higher willingness to use recycled water did not necessarily lead to higher using behavior. Second, different factors influenced willingness and behavior, with the willingness mainly influenced by cognitive and attitudinal factors, and the behavior dependent on external environmental factors such as the convenience of installation and promotion measures. Third, the convenience of the installation of recycled water facilities is the most important factor influencing both willingness and behavior, and inconvenient facilities are the main factor hindering the use of recycled water.

Urban Residents' Acceptance Intention to Use Recycled Stormwater-An Examination of Values, Altruism, Social and Cultural Norms, and Perceived Health Risks

Public acceptance is the basic premise for the implementation of stormwater reuse projects anywhere in the world. Based on the theory of planned behaviour, this study constructed a hypothesized model of urban residents’ intention to use recycled stormwater for non-potable residential purposes. Having received 669 valid questionnaires from urban residents in Taiyuan City, a Structural Equation Model was used to analyze their acceptance intention to use recycled stormwater. Results of the study showed that the degree of human contact with recycled stormwater influenced respondents’ acceptance intention to use it for that purpose, which is consistent with previous studies. The impact of factors, including valuation of stormwater, emotions, perceived health risks, or trust in government, on respondents’ acceptance intention to use recycled stormwater was found to be not significant, which adds to the inconsistent literature. The unique contributions of the study to literature include that altruism and social and cultural norms were found to have significantly positive impacts on residents’ acceptance intention to use the water, while social and cultural norms demonstrated a more significant impact. This finding is perceived to relate to the collectivism of Chinese culture; however, to what extent the relation could be requires further research to verify. The study also makes contributions to methodology by using social networking (WeChat Moments) to collect data in social science studies.

Valuing improved water services and negative environmental externalities from seawater desalination technology: A choice experiment from the Galápagos

While seawater desalination technologies can improve drinking water supply, they can also generate significant environmental externalities. A choice experiment was implemented to investigate household preferences for potential trade-offs between improved water services and environmental impacts from seawater desalination in the Galápagos Islands. Our results indicate that households are willing to pay for water quality improvements, and for protection of coastal ecosystems and marine organisms. In contrast, households seem indifferent regarding water availability and potential impacts on air quality. Our findings also suggest that respondents who consistently reject the proposed desalination project tend to be less affluent and have stronger environmental preferences than those who support it. It is concluded that stated-preference studies on improved water services should also elicit preferences for potential environmental effects of the proposed water technology.

An Analysis of Household Perceptions of Water Costs across the United States: A Survey Based Approach

Research analyzing perceptions of water services has focused on water quality, water safety, and the propensity to consume water from different sources. It has not assessed perceptions of water costs. To address this knowledge gap, this study collected nationally representative survey data from households in the United States about water issues and incorporated these data into logistic regression models. In doing so, our study advances the water and public policy literature in three ways. One, it addresses the need for household resolution information about water issues given the absence of data at this scale in the United States. Two, it creates and utilizes one-of-a-kind survey data to understand the perceptions of household water bills and the drivers of these perceptions. Three, we assess the impact of proposed solutions to improve water affordability on household perceptions of water costs. Model results indicate low-income and households in underrepresented groups were more likely to perceive their water bills to be too high. The perception of water costs also varied geographically. From a policy perspective, model results indicate utilities can positively affect perceptions of water bills via the frequency of water billing and provision of payment assistance programs.

Managing Water Scarcity Futures: Identifying Factors Influencing Water Quality, Risk Perception and Daily Practices in Urban Environments after the Introduction of Desalination

During the last two decades on a global scale, there has been a significant development of desalination as a strategy to ensure the urban water supply in arid and semi-arid areas. Beyond issues related to the higher economic costs, one of the main barriers that may limit this water source’s development is its supposed negative water quality perception. This research aims to understand better which factors are behind water quality perception in Antofagasta (Chile), where desalinated water was introduced in 2003. Since then, this urban water supply system has increasingly incorporated desalination, creating three parallel areas according to the water sources used in each of them (desalinated water, freshwater and a mix of both). To do so, more than 800 questionnaires to test water quality perception and water consumption habits were conducted in households. Up to six logistic regression models have been implemented to identify which variables better explain water quality satisfaction, risk perception and daily water practices considering the water supply area. It is worth noting that most of this type of research has been carried out in study cases with homogeneous urban water supply systems with conventional water resources. Results indicate that, among other factors, organoleptic water characteristics, such as taste, and socioeconomic status are some of the main factors that explain the perception of water quality and daily practices. In addition, a lower water quality perception and greater risk perception have been identified where desalinated water has been introduced, which makes some households develop averting behaviors to improve water quality, such as boil water.

Reverse Osmosis Concentrate: Physicochemical Characteristics, Environmental Impact, and Technologies

This study's aim is to generate a complete profile of reverse osmosis concentrate (ROC), including physicochemical characteristics, environmental impact, and technologies for ROC treatment, alongside element recovery with potential valorization. A systematic literature review was used to compile and analyze scientific information about ROC, and systematic identification and evaluation of the data/evidence in the articles were conducted using the methodological principles of grounded data theory. The literature analysis revealed that two actions are imperative: (1) countries should impose strict regulations to avoid the contamination of receiving water bodies and (2) desalination plants should apply circular economies. Currently, synergizing conventional and emerging technologies is the most efficient method to mitigate the environmental impact of desalination processes. However, constructed wetlands are an emerging technology that promise to be a viable multi-benefit solution, as they can provide simultaneous treatment of nutrients, metals, and trace organic contaminants at a relatively low cost, and are socially accepted; therefore, they are a sustainable solution.

Uncovering the research progress and hotspots on the public use of recycled water: a bibliometric perspective

With the scarcity of water resources and the development of recycled water production technology, the promotion of global recycled water use is attracting more and more attention. An increasing number of publications have examined the reuse of recycled water from different perspectives to promote the sustainable use of global water resources. The purpose of this research is to systematically and comprehensively evaluate the knowledge structure, development trends, research hotspots, and frontier predictions in the global research field of recycled water use. Based on 910 screened articles from the Web of Science Core Collection from 1990 to 2020, this paper visualizes and analyzes recycled water use from the perspectives of scientific output characteristics, research collaboration networks, highly cited articles and core journals, and keywords. The results indicate that research interest in recycled water use is on the rise. Authoritative experts, high-impact institutions, and core journals are also identified. The study shows that water resources management, public health, and public acceptance are all hot topics and frontiers of research. This study provides valuable guidance for researchers to support recycled water research directions and regulatory authorities for the interest in recycled water use.

Pharmaceuticals in edible crops irrigated with reclaimed wastewater: Evidence from a large survey in Israel

Pharmaceuticals and other contaminants of emerging concern (CECs) are continuously introduced into the agroecosystem via reclaimed wastewater irrigation, a common agricultural practice in water-scarce regions. Although reclaimed wastewater irrigated crops are sold and consumed, only limited information is available on the occurrence of pharmaceuticals and other CECs in edible produce. Here, we report data on CECs in irrigation water, soils, and crops collected from 445 commercial fields irrigated with reclaimed wastewater in Israel. The following produce were analyzed: leafy greens, carrot, potato, tomato, orange, tangerine, avocado, and banana. Pharmaceuticals and CECs were found in quantifiable levels in all irrigation water, soils, and plants (>99.6%). Leafy greens exhibited the largest number and the highest concentration of pharmaceuticals. Within the same crop, contamination levels varied due to wastewater source and quality of treatment, and soil characteristics. Anticonvulsants (carbamazepine, lamotrigine, and gabapentin) were the most dominant therapeutic group found in the reclaimed wastewater-soil-plant continuum. Antimicrobials were detected in ~85% of the water and soil samples, however they exhibited low detection frequencies and concentrations in produce. Irrigation with reclaimed wastewater should be limited to crops where the risk for pharmaceutical transfer to the food chain is minimal.

Perceptions of water as commodity or uniqueness? The role of water value, scarcity concern and moral obligation on conservation behavior

Water shortage will be an urgent worldwide concern in the coming decennia. This study examines individuals' perceptions of water's uniqueness in order to explore how these relate to (self-reported) conservation behaviors. The results of an online survey (n = 1013) in a Western European country showed that perceptions of water as a natural resource with unique assets positively influenced the value individuals attach to water and increased their concerns related to its scarcity. Both of these mediating variables (perceived water value and water scarcity concerns) strengthen individuals' moral obligations to conserve water, which appears to be an important mediating variable with regard to the positive impact perceived water uniqueness has on conservation behavior. People's perceptions of water's uniqueness are influenced by attributes focusing on its aesthetics and pureness, the hedonic (experiential) dimension of water, and, to a lesser extent, its naturalness. The utilitarian dimension of water does not predict the level of perceived uniqueness, and perceptions of water availability relate negatively to the perceived uniqueness of water. In particular, older females and respondents with a lower education level perceived the uniqueness of water to be high. The results of this study provide guidelines on how policy makers can promote water conservation by focusing on the meaning individuals attribute to water as a long-term behavioral change strategy. When individuals approach water as a commodity, the urge to conserve water is likely to stay low.

Capturing and analysing heterogeneity in residential greywater reuse preferences using a latent class model

To legally permit greywater reuse as a management strategy, it is necessary to establish allowed uses, as well as guarantee legitimacy, safety and maintain public trust. Cities with previous experience in greywater reuse have reconfigured their regulations according to their own evidence with decentralized water reuse systems. This has allowed them to encourage or restrict certain indoor uses of treated greywater. However, cities starting to use these residential schemes lack the experience to reconfigure their water and sanitation regulation, and thus need "blindly" decide on the type of greywater uses to allow in order to achieve a balance between users' acceptability and avoiding public health problems. In this research, we analyse hypothetical situations of greywater reuse based on real evidence related to decentralized water systems. The main objective of this study is to evaluate the heterogeneity of individuals' preferences regarding residential greywater reuse for six intended indoor uses, using stated choice experiments and a latent class model. Hence, we obtain preliminary evidence about the direction that the regulation or pilot tests should take. We use the context of Santiago (Chile) as a reference, where although allowed, greywater reuse is not taking place widely. Our results show that survey respondents can be classified into four classes (enthusiasts, greywater sceptics, appearance conscious and water expenditure conscious), according to the preferences for the different types of indoor greywater reuse and the appearance of the treated greywater. From a policy perspective, our results show differences across classes as a function of socioeconomic characteristics and previous greywater reuse knowledge, as well as wider household characteristics, including the presence of sensitive individuals (under 15 and over 74 years old), number of residents, number of sanitary devices, and location and type of garden.

Local resident perceptions of water reuse in Northern Utah

The reuse of municipal wastewater is increasingly implemented in cities to mitigate intensifying water supply problems. Public acceptance of water reuse is integral to successful implementation. This study uses survey research to explore local perspectives and uses of secondary (nonpotable) water for irrigation in two northern Utah cities-one that has implemented water reuse and one that has not. Findings revealed few differences between cities, suggesting that experience with water reuse may not influence acceptance or risk perception levels as long as it is limited to certain less direct purposes. In line with previous research, general support was found for water reuse for irrigation with relatively low health risk perceptions. Water reuse support was higher (and health risk perceptions lower) for those agreeing with the environmental and economic responsibility of water reuse. Having heard of water reuse was not related to health risk perceptions in either city. However, in the city with water reuse, those more familiar with the system had lower health risk perceptions and higher levels support for reuse for irrigation. Results suggest public acceptance of water reuse may not always be a barrier to local implementation, though continued communication about water reuse systems is important. PRACTITIONER POINTS: Risk perception of water reuse for irrigation was relatively low, particularly for more indirect uses such as irrigation. Public perspectives on water reuse for irrigation did not differ significantly between a community with water reuse for irrigation and one without. Environmental and economic motivations for water reuse offset risk perceptions, suggesting that public opposition to water reuse may not be a barrier in contexts in which water is understood to be a scarce resource. Awareness of local water reuse was not high and influenced risk perception, suggesting the need for ongoing communication.

Reducing the Impacts of Biofouling in RO Membrane Systems through In Situ Low Fluence Irradiation Employing UVC-LEDs

Biofouling is a major concern for numerous reverse osmosis membrane systems. UV pretreatment of the feed stream showed promising results but is still not an established technology as it does not maintain a residual effect. By conducting accelerated biofouling experiments in this study, it was investigated whether low fluence UV in situ treatment of the feed using UVC light-emitting diodes (UVC-LEDs) has a lasting effect on the biofilm. The application of UVC-LEDs for biofouling control is a novel hybrid technology that has not been investigated, yet. It could be shown that a low fluence of 2 mJ∙cm^-2 delays biofilm formation by more than 15% in lab-scale experiments. In addition, biofilms at the same feed channel pressure drop exhibited a more than 40% reduced hydraulic resistance. The delay is probably linked to the inactivation of cells in the feed stream, modified adsorption properties or an induced cell cycle arrest. The altered hydraulic resistance might be caused by a change in the microbial community, as well as reduced adenosine triphosphate levels per cells, possibly impacting quorum sensing and extracellular polymeric substances production. Due to the observed biofilm attributes, low fluence UV-LED in situ treatment of the feed stream seems to be a promising technology for biofouling control.

Assessing the public perceptions of treated wastewater reuse: opportunities and implications for urban communities in developing countries

Wastewater reuse has become an integral part of Integrated Water Resources Management and thus plays a role in securing the water needs for future generations. This study aimed at determining the perceptions of Canaanland, an emerging urban community in Ogun State, Nigeria, on treated wastewater reuse for several purposes. Data were collected through questionnaires administered to the city residents (n = 244). Findings revealed that the city was aware of the economic and environmental benefits of wastewater reuse but would prefer reuse schemes that involved less human contact such as flushing toilets, electricity generation, building construction, and car wash. The least preferred option was for potable purposes. The community also revealed that they would be willing to accept wastewater reuse as long as it is endorsed by medical doctors, university professors, and experts. However, 45.5% of the respondents were from the Covenant University academic environment. Also, an assessment was carried out to ascertain the implications and opportunities for wastewater reuse in the city. Findings indicated that wastewater reuse involves several complexities and interlinkages, which revolve around political and decisional factors, economic and social factors, environmental factors, and technological factors. From the study, policy and decisional suggestions and a wastewater process flow were developed for more efficient wastewater management within developing cities. A study was carried out on eight cities from developing nations that have created a framework for wastewater management using several approaches. Also, a summary of findings reveals that if adequately researched, cheap and alternative means of wastewater treatment and reuse could be developed for electricity generation, carwash, and firefighting for developing nations. The result of this research can be used to address public anxieties regarding wastewater-reuse practices. Additionally, this study hopes to aid successful wastewater management schemes in the foreseeable future.

Water end-use estimation can support the urban water crisis management: A critical review

The present study reviews the overall perspectives of end-use studies on urban water crisis management by analysing their beneficial application in water conservation and wastewater recycling. The paper incorporates a critical review of water end-use consumption of 16 major countries from 3 major continents, i.e. Asia, Europe, and Australia. The study reflected a different trend between the water consumption of developed and developing nations, thereby implying a need for separate prospects of end-use results in these countries. Besides, the percentage of greywater generated varies from 54% to 86% of the total indoor household water consumption and thus can be a valuable water resource to solve the urban water crisis. There exists a strong correlation between the amount of greywater generated and the amount of water used for the shower (R² = 0.69) and laundry (R² = 0.50). The same, i.e. R² values, for end-uses of the toilet flushing, dishwashing, and indoor taps with the amount of greywater, were found to be 0.30, 0.26, and 0.04, respectively. Further, except for the end-use pertaining to indoor taps, water consumption of all other end-uses has witnessed an upward spiral in developing countries with time, which may be attributed to the improved accuracy of collected end-use data or increased contribution of 'leaks/others' category. In developed nations like the USA, there is not a single end-use that has shown an absolute increase with time owing to a variety of measures such as increased awareness, education, retrofitting of appliances and several other factors like governmental restrictions. Change in attitude or/and behaviour of people towards water use driven by drought-like experience could also be a valid reason. After this extensive review of the end-use pattern, we proposed specific greywater recycling models that are expected to help engineers, governments, and policymakers in sustainable urban water management.

Measuring objective knowledge of potable recycled water

Reliable clean drinking water is becoming increasingly scarce. One potential additional source of drinking water is recycled water. However, public acceptance of potable recycled drinking water is low. One likely factor involved in the acceptance of recycled drinking water is objective knowledge about recycled water. In three studies (N = 229,  590, and 200), we developed a 34-item measure of objective knowledge of recycled drinking water. The objective knowledge measure was often a strong and unique predictor of intentions to accept and use recycled drinking water compared to other prominent factors including disgust and subjective knowledge of recycled water. Measuring knowledge of recycled drinking water holds the potential to estimate how and whether educational interventions aimed at increasing acceptance of recycled drinking water programs work.

Public acceptability of treated wastewater reuse in Saudi Arabia: Implications for water management policy

Treated wastewater reuse is increasingly important for sustainable water resource management, especially in water-stressed countries located in the world's arid regions that rely on groundwater and desalination process for meeting their water demands. This study investigates the socio-demographic variables influencing public perceptions of reusing grey and mixed wastewater for non-domestic uses: firefighting, swimming pools, and car washing. Data were collected from 624 households in the Dammam Metropolitan Area, Saudi Arabia using a structured questionnaire and analyzed using descriptive and inferential statistics. The results from logistic regression indicates that the likelihood of a household to accept reusing treated mixed wastewater is influenced by gender with odds ratio (OR) of 2.71-2.18, residential location (OR = 1.32-1.03), age (OR = 1.22-0.18) and educational level (OR = 1.33-0.98), with a tendency for more acceptance of treated grey wastewater than mixed wastewater. These findings showcase the difficulty that the country could face concerning the public acceptance of treated wastewater for non-domestic uses to augment current freshwater sources even among the educated class. This study is significant because sustainably meeting the country's rising water demands requires the stringent implementation of strategic wastewater reuse policy, including bold steps towards wastewater streams segregation, and intensive public awareness campaigns to change negative perceptions on treated sewage effluent. This study concludes that a substantial reduction in the country's reliance on costly desalinated water and fast depleting non-renewable groundwater requires complete reuse and recycling of treated wastewater for wider non-conventional purposes.

Recycled and desalinated water: Consumers' associations, and the influence of affect and disgust on willingness to use

Traditional water sources are increasingly coming under pressure from urbanization, population and industrial growth as well as climate variability and alternatives such as desalinated and recycled water will need to be considered in the future. However, available data indicate that consumers are apprehensive about these alternative water sources, with many reactions centered on disgust. It is not clear though, whether trait or state disgust is responsible for these disgust reactions. Secondly, the associations the public has with desalinated and recycled water are not well described, even though knowledge of these associations would provide the holistic understanding required for addressing perceptions. Using respondents from Australia and South Africa, therefore, this study investigated the associations people have with recycled and desalinated water, as well as the influence of affect, institutional trust, cultural/religious beliefs, water scarcity, and demographic variables, on willingness to use (WTU) these waters. The results show that whereas recycled water is associated with negative affect from notions of disgust, desalinated water is often thought of in terms of minerals, or as "simply water". We also found that affect was the most significant predictor, and that state disgust as well as trait disgust influenced WTU. Together these data suggest that disgust-related rejection of is likely due to the disgust elicited by the waters rather than disgust-proneness of individuals. It is plausible, therefore, that efforts to induce positive affect through making salient positive associations e.g. NEWater in Singapore, may increase WTU.

Recycled or reclaimed? The effect of terminology on water reuse perceptions

Successful water recycling initiatives depend on public acceptance. In this study, we compared risk percpetions of water labeled as recycled or reclaimed.We recruited 1264 subjects in an online panel (Qualtrics) and randomly assigned them either treatment (recycled or reclaimed) water and asked about the contents and perceived risk. Participants in the reclaimed condition were more likely to perceive the water to have harmful ingredients compared to the recycled condition. The odds of direct use acceptance for those in the recycled condition are 1.41 times (or 41%) more likely than those in the reclaimed condition. Similar results were found for indirect uses. A major finding of this study is that terminology influences the perceived contaminants and risk of reused water. Prior studies have found strong evidence that the way reused water is communicated can influence public perception. Policy impilcations favor the use of recycled water, likely due to the positive connotation recycling has in the U.S. today..

Health assessment of spatial and temporal distribution of arsenic in soils irrigated with reclaimed water

Reclaimed water is an important water resource for agricultural irrigation. Based on the systematic analysis of experimental data, this paper studies the spatiotemporal transformation and distribution of As in soil-crop system. Through the comparison with groundwater irrigation, reclaimed water irrigation was tested and studied in connection with the greenhouse vegetables in the growing season. The accumulation, distribution and transportation of As in different depths of soil within 7 days after reclaimed water irrigation were analyzed and discussed. The results showed that the concentration of As was the highest on the first day after irrigation; it was the highest at the depth of 100 cm on the third day after irrigation, but its concentration in the topsoil slightly decreased; from the fifth to the seventh day, the concentrations of As in the different layers of soil were almost the same, but it was the highest at the depth of 80-120 cm; and it decreased slightly with the increase in depth when the depth was less than 120 cm. As in soil during the growing season varied as the frequency of irrigation increased. The specific situation was as follows: as the accumulated As in the topsoil increased, the increased As at the depth of 80-120 cm would become less and the concentration of As at 200 cm would fall. Therefore, when the appropriate concentration of reclaimed water is used for irrigation, the concentration of As in the deep layer soil will comply with the standard limits of GB15618-1995 and the irrigation with reclaimed water of appropriate concentration will not cause As pollution.

Reclaimed water and food production: Cautionary tales from consumer research

Reclaimed water has been identified as a viable and cost-effective solution to water shortages impacting agricultural production. However, lack of consumer acceptance for foods irrigated with reclaimed and treated water remains one of the greatest hurdles for widespread farm-level adoption. Using survey data from 760 participants in the mid-Atlantic region of the U.S., this paper examines consumer preferences for six sources of reclaimed irrigation water and identifies statistically significant relationships between consumers' demographic characteristics and their preferences for each type of reclaimed water. Key findings suggest that adult consumers prefer rain water to all other sources of reclaimed water. Women are less likely than men to prefer reclaimed irrigation water sources and are particularly concerned about the use of black and brackish water. Consumers who had heard about reclaimed water before are more likely to accept its use. Drawing on evidence from survey and experimental research, this paper also identifies disgust, neophobia and safety concerns as the key issues that lead consumers to accept or reject foods produced with reclaimed water. Finally, we identify avenues for future research into public acceptance of reclaimed water based on our analysis and evidence from prior research.

Understanding grower perceptions and attitudes on the use of nontraditional water sources, including reclaimed or recycled water, in the semi-arid Southwest United States

The use of nontraditional water sources, including reclaimed or recycled water, has become a desirable option to meet increasing demands in water stressed regions. In the Southwest United States, utilization of alternative water sources is becoming increasingly common, including use for landscape irrigation, environmental enhancement, cooling and power generation, potable reuse, and as a source water for agricultural irrigation. While much research has gone into identifying public perception towards water reuse schemes, little attention has been given to understanding grower attitudes, perceptions, and knowledge on the use of nontraditional water, including reclaimed water, in agriculture and how that may influence grower acceptance and production practices. This unique study utilized a needs assessment survey of growers (n = 521) within the Southwest region of the United States to gain an understanding of industry attitudes and needs regarding nontraditional water in agriculture. Results indicate that the majority of survey respondents were concerned with water availability (67.49%) yet less than half (48.30%) thought using a nontraditional water source in agriculture was 'very important'. Interestingly, respondents rated irrigation of 'food crops' third (42.20%) among agricultural activities for which they would be willing to use nontraditional water sources, behind irrigation of forage crops (61.60%) and dust control (61.60%). The importance of the use of nontraditional water sources in agriculture was influenced mostly by farm size (p = 0.007) and primary water source (p = 0.016), and the level of education was significant in respondent's level of concern over water availability (p = 0.021). Information on the quality of nontraditional water sources, showing that it is as good or better than respondents current sources, was found to shift rejection and uncertainty towards acceptance by 16.04%. The results of this study provide insight into perceived risks, willingness to use, drivers and constraints to grower adoption, and preferred methods of education regarding water reuse in agriculture. These findings can be used by water managers and planners to aid in the adoption of nontraditional waters, including reclaimed or recycled water, in agriculture thus extending water resources, securing food supplies, and protecting public health.

Justice Implications of Clean Energy Policies and Programs in the United States: A Theoretical and Empirical Exploration

This paper offers both theoretical and empirical analyses to explore energy justice from a policy perspective. We first propose a framework that explicitly connects core functions of clean energy policy instruments (i.e., regulation, financial incentive, government provision, information, and education program) to philosophical groundings of energy justice—distributive, procedural, and recognition justice. To empirically explore distributive energy justice, we examine the racial and socioeconomic disparities in three government-driven clean energy programs in the United States, including (1) the American Recovery and Reinvestment Act (ARRA) smart-grid investment grant (SGIG); (2) utility smart-meter roll out programs; and (3) city government adoption of green buildings. Results showed that the amount of ARRA funding awarded to utilities was closely related to racial composition. Inequalities were also found in utility smart-meter programs. Utilities operating in communities with a larger Hispanic population were less likely to initiate smart-meter roll out. The intensity of smart-meter technology implementation was positively correlated with education levels. Our third empirical case showed that government procurement policy can improve distributive equity for energy-efficient buildings. However, its spillover effects on the private sector can result in more adoptions in areas with fewer minorities and more highly-educated residents.

Risk-Yuck Factor Nexus in Reclaimed Wastewater for Irrigation: Comparing Farmers’ Attitudes and Public Perception

The successes and failures of water reuse schemes are shaped by complex interrelationships between technological, economic, and socio-political factors. However, it has long been recognized that the main challenges to more effective water management are largely social rather than technical. This article reviews the recent literature (2007–2017) to analyze driving factors associated with farmers’ concerns and public perception of reclaimed wastewater for irrigation. The aim of the paper is to synthetize how both environmental and health risks and the yuck factor could be addressed in order to promote mutual understanding between farmers and the public. Results show: (1) how farmers and the public perceive environmental and health risks in a similar way, (2) how the yuck factor is more noticeable for the public than farmers, and (3) how constructed wetlands, reclaimed water exchange consortiums, product certification, and direct site visits to water reuse infrastructure could be promoted in order to foster understanding between farmers and the public. The article concludes by providing key research questions for managers and public authorities relating to how to focus on the study of technical and social issues related to water reuse.

Multi-Water Source Joint Scheduling Model Using a Refined Water Supply Network: Case Study of Tianjin

Water shortage problems are increasing in many water-deficient areas. Most of the current research on multi-source combined water supplies depends on an overall generalization of regional water supply systems, which are seldom broken down into the detail required to address specific research objectives. This paper proposes the concept of a water treatment and distribution station (water station), and generalizes the water supply system into three modules: water supply source, water station, and water user. Based on a topological diagram of the water network (supply source–station–user), a refined water resource allocation model was established. The model results can display, in detail, the water supply source, water supply quantity, water distribution engineering, and other information of all users in each water distribution area. This makes it possible to carry out a detailed analysis of the supply and demand of users, and to provide suggestions and theoretical guidance for regional water distribution implementation. Tianjin’s water resource allocation was selected as a case study, and a water resource allocation scheme for a multi-source, combined water supply, was simulated and discussed.

Statistical monitoring of a wastewater treatment plant: A case study

The efficient operation of wastewater treatment plants (WWTPs) is key to ensuring a sustainable and friendly green environment. Monitoring wastewater processes is helpful not only for evaluating the process operating conditions but also for inspecting product quality. This paper presents a flexible and efficient fault detection approach based on unsupervised deep learning to monitor the operating conditions of WWTPs. Specifically, this approach integrates a deep belief networks (DBN) model and a one-class support vector machine (OCSVM) to separate normal from abnormal features by simultaneously taking advantage of the feature-extraction capability of DBNs and the superior predicting capacity of OCSVM. Here, the DBN model, which is a powerful tool with greedy learning features, accounts for the nonlinear aspects of WWTPs, while OCSVM is used to reliably detect the faults. The developed DBN-OCSVM approach is tested through a practical application on data from a decentralized WWTP in Golden, CO, USA. The results from the DBN-OCSVM are compared with two other detectors: DBN-based K-nearest neighbor and K-means algorithms. The results show the capability of the developed strategy to monitor the WWTP, suggesting that it can raise an early alert to the abnormal conditions.

Factors influencing the reuse of reclaimed water as a management option to augment water supplies

The reuse of treated wastewater, whether direct or indirect, can raise public concerns as a result of the overall risk perception. As such, community acceptance plays a significant role in the implementation of alternative water systems. Public attitudes towards water reuse are highly influenced by perceived health risk, religious prohibition, political issues, and the degree of human contact with recycled water. In most of the Mediterranean countries, wastewater is reused to different extents either within planned or unplanned schemes. Unfortunately, there are few in-depth studies of the socio-cultural aspects of reuse projects in developing countries, and Lebanon is no exception. Accordingly, this research will comprehensively tackle the issue of public knowledge, perceptions, and acceptance from different perspectives in an effort to provide national baseline information on wastewater reuse that is needed for future regulatory and developmental projects. As such, a survey was developed, tested, and administered. Results showed an inverse relation between the degree of human contact with the treated wastewater and public acceptance. People were found to be more inclined towards reuse for purposes with minimal human contact such as landscaping and agriculture with opposition when it came to use for personal use. Moreover, the results showed a general lack of trust in governing institutions and authorities, which could explain perceived health risks and perceptions of risk resulting from system failure. Overall, the willingness to use treated wastewater was found to vary as a function of the "disgust factor," religious beliefs, and perceptions of a high risk towards contracting waterborne diseases. The disgust towards reuse of treated wastewater was found to be a strong predictor affecting willingness to reuse whereby those who believed it is disgusting to reuse treated wastewater were found to be on average, three times less likely to reuse treated wastewater as compared to those who did not declare disgust. Similarly, a significant association was found between religious beliefs and respondents' willingness to use treated wastewater. Interviewees who thought treated wastewater reuse is not religiously accepted were, on average, twice less likely to use treated wastewater as compared to those who did not believe that reuse contradicts with their religious beliefs. Additionally, people's perceptions on associating the spread of water-borne diseases with reuse were found to be significant. Those who perceived that reusing treated wastewater would lead to diseases and affect the human health, were on average, twice less likely to accept reuse. Developing a comprehensive strategy that integrates increasing awareness and knowledge, setting policies related to water reuse, building public trust and communication channels, increasing public participation/engagement in decision making, and developing a sustainable management framework is thus crucial before any investments are made in reclaimed water-reuse projects.

Influence of Household Water Filters on Bacteria Growth and Trace Metals in Tap Water of Doha, Qatar

Deteriorating water quality from aging infrastructure, growing threat of pollution from industrialization and urbanization, and increasing awareness about waterborne diseases are among the factors driving the surge in worldwide use of point-of-entry (POE) and point-of-use (POU) filters. Any adverse influence of such consumer point-of-use systems on quality of water at the tap remains poorly understood, however. We determined the chemical and microbiological changes in municipal water from the point of entry into the household plumbing system until it leaves from the tap in houses equipped with filters. We show that POE/POU devices can induce significant deterioration of the quality of tap water by functioning as traps and reservoirs for sludge, scale, rust, algae or slime deposits which promote microbial growth and biofilm formation in the household water distribution system. With changes in water pressure and physical or chemical disturbance of the plumbing system, the microorganisms and contaminants may be flushed into the tap water. Such changes in quality of household water carry a potential health risk which calls for some introspection in widespread deployment of POE/POU filters in water distribution systems.

Association between perceptions of public drinking water quality and actual drinking water quality: A community-based exploratory study in Newfoundland (Canada)

Studying public perception on drinking water quality is crucial for managing of water resources, generation of water quality standards, and surveillance of the drinking-water quality. However, in policy discourse, the reliability of public perception concerning drinking water quality and associated health risks is questionable. Does the public perception of water quality equate with the actual water quality? We investigated public perceptions of water quality and the perceived health risks and associated with the actual quality of public water supplies in the same communities. The study was conducted in 45 communities of Newfoundland (Canada) in 2012. First, a telephone survey of 100 households was conducted to examine public perceptions of drinking water quality of their respective public sources. Then we extracted public water quality reports of the same communities (1988-2011) from the provincial government's water resources portal. These reports contained the analysis of 2091 water samples, including levels of Disinfection By-Products (DBPs), nutrients, metals, ions and physical parameters. The reports showed that colour, manganese, total dissolved solids, iron, turbidity, and DBPs were the major detected parameters in the public water. However, the majority of the respondents (>56%) were either completely satisfied or very satisfied with the quality of drinking water. Older, higher educated and high-income group respondents were more satisfied with water quality than the younger, less educated and low-income group respondents. The study showed that there was no association with public satisfaction level and actual water quality of the respective communities. Even, in the communities, supplied by the same water system, the respondents had differences in opinion. Despite the effort by the provincial government to make the water-test results available on its website for years, the study showed existing disconnectedness between public perception of drinking water quality and actual quality. We had little scope to explore the possible explanations, and hence further studies are required to verify the age, gender educational status and income differential about the satisfaction of public service like water supply.

An Empirical Agent-Based Model to Simulate the Adoption of Water Reuse Using the Social Amplification of Risk Framework

Water reuse can serve as a sustainable alternative water source for urban areas. However, the successful implementation of large-scale water reuse projects depends on community acceptance. Because of the negative perceptions that are traditionally associated with reclaimed water, water reuse is often not considered in the development of urban water management plans. This study develops a simulation model for understanding community opinion dynamics surrounding the issue of water reuse, and how individual perceptions evolve within that context, which can help in the planning and decision-making process. Based on the social amplification of risk framework, our agent-based model simulates consumer perceptions, discussion patterns, and their adoption or rejection of water reuse. The model is based on the "risk publics" model, an empirical approach that uses the concept of belief clusters to explain the adoption of new technology. Each household is represented as an agent, and parameters that define their behavior and attributes are defined from survey data. Community-level parameters-including social groups, relationships, and communication variables, also from survey data-are encoded to simulate the social processes that influence community opinion. The model demonstrates its capabilities to simulate opinion dynamics and consumer adoption of water reuse. In addition, based on empirical data, the model is applied to investigate water reuse behavior in different regions of the United States. Importantly, our results reveal that public opinion dynamics emerge differently based on membership in opinion clusters, frequency of discussion, and the structure of social networks.

Early testing of new sanitation technology for urban slums: The case of the Blue Diversion Toilet

The toilets used most in informal urban settlements have detrimental consequences for the environment and human health due to the lack of proper collection and treatment of toilet waste. Concepts for safe, sustainable and affordable sanitation systems exist, but their feasibility and acceptance have to be investigated at an early stage of development, which is difficult due to the high costs of building working models. In this paper, we present an approach to estimate acceptance in a valid and representative form with only one working model, and apply it to test an innovative zero-emission toilet with recycling of wash water. Four basic principles were specified for investigation and nine hypotheses formulated to test the feasibility and acceptance of these principles: source separation of urine and feces with subsequent collection for resource recovery; provision of wash water in a separate cycle with on-site recovery through a membrane bioreactor; a convenient and attractive overall design; and a financially sustainable business plan. In Kampala (Uganda), in 2013, data was collected from 22 regular users, 308 one-time users and a representative sample of 1538 participants. Qualitative data was collected from the users, who evaluated their likes, perceived benefits, social norms and expected ease of use based on verbal and visual information. Most of the hypotheses were confirmed, indicating the feasibility and acceptance of the basic principles. Source separation and on-site water recovery were found to be feasible and accepted, provided users can be convinced that the emptying service and water recovery process work reliably. In the survey, the toilet was evaluated favorably and 51% of the participants agreed to be placed on a bogus waiting list. However, some design challenges were revealed, such as the size of the toilet, hiding feces from view and improving the separation of urine and water.

Investigating the Energy-Water Usage Efficiency of the Reuse of Treated Municipal Wastewater for Artificial Groundwater Recharge

This project investigates the energy-water usage efficiency of large scale civil infrastructure projects involving the artificial recharge of subsurface groundwater aquifers via the reuse of treated municipal wastewater. A modeling framework is introduced which explores the various ways in which spatially heterogeneous variables such as topography, landuse, and subsurface infiltration capacity combine to determine the physical layout of proposed reuse system components and their associated process energy-water demands. This framework is applied to the planning and evaluation of the energy-water usage efficiency of hypothetical reuse systems in five case study regions within the State of California. Findings from these case study analyses suggest that, in certain geographic contexts, the water requirements attributable to the process energy consumption of a reuse system can exceed the volume of water that it is able to recover by as much as an order of magnitude.

Why Do Some Water Utilities Recycle More than Others? A Qualitative Comparative Analysis in New South Wales, Australia

Although the recycling of municipal wastewater can play an important role in water supply security and ecosystem protection, the percentage of wastewater recycled is generally low and strikingly variable. Previous research has employed detailed case studies to examine the factors that contribute to recycling success but usually lacks a comparative perspective across cases. In this study, 25 water utilities in New South Wales, Australia, were compared using fuzzy-set Qualitative Comparative Analysis (fsQCA). This research method applies binary logic and set theory to identify the minimal combinations of conditions that are necessary and/or sufficient for an outcome to occur within the set of cases analyzed. The influence of six factors (rainfall, population density, coastal or inland location, proximity to users; cost recovery and revenue for water supply services) was examined for two outcomes, agricultural use and "heavy" (i.e., commercial/municipal/industrial) use. Each outcome was explained by two different pathways, illustrating that different combinations of conditions are associated with the same outcome. Generally, while economic factors are crucial for heavy use, factors relating to water stress and geographical proximity matter most for agricultural reuse. These results suggest that policies to promote wastewater reuse may be most effective if they target uses that are most feasible for utilities and correspond to the local context. This work also makes a methodological contribution through illustrating the potential utility of fsQCA for understanding the complex drivers of performance in water recycling.

Beyond User Acceptance: A Legitimacy Framework for Potable Water Reuse in California

Water resource managers often tout the potential of potable water reuse to provide a reliable, local source of drinking water in water-scarce regions. Despite data documenting the ability of advanced treatment technologies to treat municipal wastewater effluent to meet existing drinking water quality standards, many utilities face skepticism from the public about potable water reuse. Prior research on this topic has mainly focused on marketing strategies for garnering public acceptance of the process. This study takes a broader perspective on the adoption of potable water reuse based on concepts of societal legitimacy, which is the generalized perception or assumption that a technology is desirable or appropriate within its social context. To assess why some potable reuse projects were successfully implemented while others faced fierce public opposition, we performed a series of 20 expert interviews and reviewed in-depth case studies from potable reuse projects in California. Results show that proponents of a legitimated potable water reuse project in Orange County, California engaged in a portfolio of strategies that addressed three main dimensions of legitimacy. In contrast, other proposed projects that faced extensive public opposition relied on a smaller set of legitimation strategies that focused near-exclusively on the development of robust water treatment technology. Widespread legitimation of potable water reuse projects, including direct potable water reuse, may require the establishment of a portfolio of standards, procedures, and possibly new institutions.