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

Long-term resilience in wastewater management: Optimizing treated wastewater allocation with a dynamic multi-agent approach

Water scarcity poses a significant challenge to sustainable development, necessitating innovative approaches to manage limited resources efficiently. Effective water resource management involves not just the conservation and distribution of freshwater supplies but also the strategic reuse of treated wastewater (TWW). This study proposes a novel approach for the optimal allocation of treated wastewater among three key sectors (user agents): agriculture, industry, and urban green space. Recognizing the intricate interplays among these sectors, System Dynamics (SD) and Agent-Based Modeling (ABM) were integrated in a Complex Adaptive System (CAS) to capture the interactions and feedback mechanisms inherent within treated wastewater allocation systems. The Non-dominated Sorting Genetic Algorithm II (NSGA-II) serves as the optimization tool, enabling the identification of optimal allocation strategies across various management scenarios over a 25-year simulation period. Our research navigates the complexities of long-term resource management, accounting for each sector's evolving its objectives and guidelines along the whole system objectives and strategies. The outcomes demonstrate how treated wastewater can be effectively distributed to support economic and social equity -as the system objectives-while supporting agricultural and industrial growth and enhancing efficiency and social well-being -reflecting individual agent objectives-within the CAS framework. The research explores four distinct management scenarios, each prioritizing different sectors to address water resource management challenges. Notably, all four scenarios align with the strategies required by the ruler (government), providing strategic guidance to water resource managers for decision-making. The simulation results reveal a scenario where all sectors' demands are met, with Scenario 4 emerging as the most effective. Scenario 4 aligned with the objectives and guidelines of each sector, demonstrating significant improvements in the CY (Agriculture agent index; increased from 0.2 to 0.68), IGI (Industry agent index; increased from 1 to 1.63), and GAI (Urban Green Space agent index; increased from 1 to 1.23) indices over the 25-year simulation period. By providing a strategic blueprint for policymakers and stakeholders, this study contributes significantly to the discourse on sustainable water resource management, presenting a replicable model for similar contexts globally, where judicious allocation of treated wastewater is paramount for achieving harmony between human activity and ecological preservation.

Assessing greywater characteristics in the sahel region and perception of the local population on its reuse in agriculture

Research on greywater reuse in water stressed areas is in full swing. However, the perception of greywater reuse is one of the least researched areas in West Africa, particularly in Sahelian countries. This study aimed to fills a significant gap in the existing literature, which has largely ignored the specific socio-demographic contexts of developing countries in the Sahelian regions. The study involved in-depth interviews with 240 rural households and the collection of 40 greywater samples in four locations for laboratory analysis. The survey focused on greywater management and household perceptions of greywater reuse in agriculture. The analyses focused on determining the physico-chemical and microbiological parameters of greywater collected from households. The results showed that over 80 % of households discharged greywater into the natural environment without prior treatment. The majority of respondents were aware that poor greywater management poses a health risk. The results also showed an association between locality, gender, education level and perceptions of poor grey water management. Respondents were willing to accept the reuse of greywater in agriculture, to consume irrigated vegetables and to install a greywater treatment system. The quality analysis showed that the greywater was not in compliance with the legal discharge limits. This study highlights that in order to promote sustainable greywater management practices within households, it is important to design effective greywater treatment systems that meet the needs of the target population. Awareness campaigns, education and training programmes on wastewater management could also be established.

Production of polyhydroxyalkanoates using sewage and cheese whey

Recently, polyhydroxyalkanoates (PHAs) have been produced using raw sewage in our laboratory; however, the production concentrations are low. Therefore, this study aimed to enhance PHA production by applying different strategies. PHA production was higher in sewage-containing medium than in mineral salt medium and was enhanced 22-fold after glucose supplementation. A relatively high degree of glucose consumption (83.6 ± 1.59 %) was also achieved. Bacteria incubated with cheese whey diluted with sewage showed higher PHA production than bacteria incubated with cheese whey diluted with distilled water did. The expression of the PHA synthase gene (phaC) was evaluated via real-time polymerase chain reaction using low- and high-carbon-containing sewage. Relatively higher phaC expression levels were observed in high-carbon-containing sewage but at lower nitrogen concentrations. The characteristics of the produced PHA were comparable to those of standard PHA. Therefore, this study revealed that the bacterium Bacillus sp. CYR1 can produce PHA from low- or high-carbon-containing wastewater.

Reclaimed Water Reuse for Groundwater Recharge: A Review of Hot Spots and Hot Moments in the Hyporheic Zone

As an alternative resource, reclaimed water is rich in the various nutrients and organic matter that may irreparably endanger groundwater quality through the recharging process. During groundwater recharge with reclaimed water, hot spots and hot moments (HSHMs) in the hyporheic zones, located at the groundwater–reclaimed water interface, play vital roles in cycling and processing energy, carbon, and nutrients, drawing increasing concern in the fields of biogeochemistry, environmental chemistry, and pollution treatment and prevention engineering. This paper aims to review these recent advances and the current state of knowledge of HSHMs in the hyporheic zone with regard to groundwater recharge using reclaimed water, including the generation mechanisms, temporal and spatial characteristics, influencing factors, and identification indicators and methods of HSHMs in the materials cycle. Finally, the development prospects of HSHMs are discussed. It is hoped that this review will lead to a clearer understanding of the processes controlling water flow and pollutant flux, and that further management and control of HSHMs can be achieved, resulting in the development of a more accurate and safer approach to groundwater recharge with reclaimed water.

Do health risk perceptions motivate water - and health-related behaviour? A systematic literature review

Health-related risk perceptions are important determinants of health behaviours and components of behaviour change theories. What someone thinks or feels will motivate or hinder their intention or hesitancy to implement a certain behaviour. Thus, a perceived potential risk to our health and well-being can influence our health-promoting and/or health-seeking behaviour. We aimed to review and synthesize available peer-reviewed literature to better understand the links between water and health-related risk perceptions and behaviours. We conducted the first systematic review of peer-reviewed literature on risk perceptions and behaviours in the context of water and health, published between 2000 and 2021. A total of 187 publications met the inclusion criteria. We extracted data relating to study characteristics and categorized our results according to the major themes emerging from the literature, namely drinking water, sanitation, hygiene and wasterelated topics, health risk factors, diseases and mental health implications, and preventative measures. Our review shows that the literature has grown over the past twenty years, reporting information from different countries belonging to different income groups around the globe, conducted in various settings and contexts, among different target populations, from various disciplinary angles, using different methods, theories and approaches. Our review provides evidence of health risk perceptions determining behaviour particularly related to drinking water sources and water safety. Evidence on disease prevention, health seeking, variations and changes in perception and behaviour over space, geography, socioeconomic differences and time, and the relevance of cultural context is provided. Our review shows that risk perception studies are vital for WASH governance in terms of policy, raising awareness, education and behaviour change. In order to make risk perception and behaviour studies even more relevant to effective public health planning and health messaging, future research needs to increasingly focus on early culturally sensitive interventions and changes in perceptions and behaviours over time.

Development of water reuse: a global review with the focus on India

The availability of freshwater is evolving as a serious threat to the living community throughout the world due to rapid industrialization, urbanization, and rising population. The depletion of groundwater due to excessive water withdrawal and reduced recharge and pollution of the water sources also contributes to this water crisis. The rising pressure on water supplies encourages the use of treated wastewater as an alternative resource. In this study, a global outlook of the developments in water reuse is presented with a focus on the Indian scenario. It can be observed that though there is a scope for water reuse in India owing to the generation of a high volume of wastewater, it is often squandered due to limited research and guidance, and unreliable institutional framework. It is suggested that the reuse of wastewater requires the development of an integrated approach considering all the factors related to technical feasibility, financial viability, and social acceptance together with a guiding management structure that may augment the existing water supplies.

Horticultural products irrigated with treated sewage: are they acceptable?

Public acceptance of treated sewage (TS) reuse in agriculture is a key element in successful implementation of TS reuse projects, but relevant research on the topic is limited. This study examined public willingness to accept (WTA) and willingness to pay (WTP) for agricultural products derived by irrigation with TS in Lorestan province, Iran, applying the contingent valuation (CV) method. The agricultural products determined for the study included corn, peaches, apricots, and plums, while TS was introduced in three qualities [Q1, complete TS treatment (i.e., physical treatment, aeration, and chemical treatment); Q2, partial TS treatment (i.e., physical treatment and aeration); and Q3, no TS treatment]. With reference to WTA, products irrigated with Q1 TS received 62.7% positive responses, while products irrigated with Q2 TS and Q3 TS received 21.3% and 17.0% positive responses, respectively. With reference to WTP, data showed that if the price of products derived by irrigation with TS was less than that of products irrigated with fresh water, some people would be willing to pay for these products (52.0% positive responses versus 48.0% negative responses). Awareness had a significantly positive impact on WTA1 and WTA2 (products irrigated with Q1 TS and Q2 TS, respectively) as well as on WTP1, WTP2, and WTP3 (products irrigated with Q1 TS, Q2 TS, and Q3 TS, respectively). Similarly, information sources had a significantly positive effect on WTP1, WTP2, and WTP3. Overall, individuals with high levels of health risk perception and high awareness showed high WTA, while non-processed corn and men were associated with low WTA. Concerning WTP, individuals with high awareness and those who had access to information sources showed high WTP, while men were associated with low WTP. Information about the importance of TS reuse, reduction of prices of products derived by irrigation with TS, and promotion of public confidence in TS are essential to increase public WTA and WTP.

Wastewater treatment and reuse situations and influential factors in major Asian countries

As Asia is the most populous continent in the world, the contradiction between water supply and demand is increasing. Wastewater treatment and reclaimed water use are important means to solve the contradiction between supply and demand and realize the sustainability of the water management system. Based on the data collected from 48 typical countries and regions in Asia, this study evaluates the possible influential factors on wastewater treatment and reclaimed water use such as Gross Domestic Product (GDP) level, water resource availability, water withdrawn and water stress. It is identified that per capita GDP and water stress are important factors affecting wastewater treatment and reclaimed water use. Although reclaimed water use in most Asian countries is still at the early stage, the development of wastewater treatment is conducive to the development of reclaimed water. The results of this study are believed to be useful in improving water management and sustainability levels in Asian countries.

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.

Snowballing transmission of COVID-19 (SARS-CoV-2) through wastewater: Any sustainable preventive measures to curtail the scourge in low-income countries?

In this communication, we proposed sustainable preventive measures that may be adopted by the low-income countries to forestall the potential outbreak and transmission of COVID-19 (coronavirus disease 2019) through wastewater. Most low-income countries have poor sanitation and wastewater management policies, which create potential risks of COVID 19 spread. Hence, the proposed measures include decentralization of wastewater treatment facilities, community-wide monitoring and testing of SARS-CoV-2 in wastewater samples, improved sanitation, developing point-of-use devices for wastewater decontamination, and more focused policy interventions. Therefore, this paper adds useful insights into the monitoring and management of ongoing COVID-19 outbreak in low-income countries.

Snowballing transmission of COVID-19 (SARS-CoV-2) through wastewater: Any sustainable preventive measures to curtail the scourge in low-income countries?

In this communication, we proposed sustainable preventive measures that may be adopted by the low-income countries to forestall the potential outbreak and transmission of COVID-19 (coronavirus disease 2019) through wastewater. Most low-income countries have poor sanitation and wastewater management policies, which create potential risks of COVID 19 spread. Hence, the proposed measures include decentralization of wastewater treatment facilities, community-wide monitoring and testing of SARS-CoV-2 in wastewater samples, improved sanitation, developing point-of-use devices for wastewater decontamination, and more focused policy interventions. Therefore, this paper adds useful insights into the monitoring and management of ongoing COVID-19 outbreak in low-income countries.

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.

Understanding the preferences for different types of urban greywater uses and the impact of qualitative attributes

Greywater reuse can allow substantial improvements in the efficiency of potable water systems. However, widespread uptake of greywater reuse depends on its acceptability by the population. Previous studies have assessed the implementation costs of greywater reuse technology, and considered its acceptability in principle. Although cost is clearly very important in terms of adopting/installing the technology, the actual perception of greywater reuse is crucial in driving the acceptability of use and the long-term success of the technology. This study uses discrete choice models to quantify, for the first time, the preferences of different socio-economic groups for greywater of different quality (colour, odour) and for different uses inside homes. A stated choice survey that removed the influence of installation costs was developed, and implemented in Santiago, Chile. Although legislation allows greywater use in Santiago, it does not take place at any meaningful scale. Results show that, in decreasing order of preference, there is an overall acceptance for using high quality treated greywater for toilet flushing, laundry, garden irrigation, hand washing and, shower/bathtub use, but not for drinking. When the quality of appearance in terms of colour and odour gets worse, monetary incentives could be needed even for those uses that do not involve human contact. Gender, age, educational level, water expenditure level, and in particular previous knowledge about greywater reuse, are important determinants of acceptability and thus willingness to pay for greywater use; however, their importance varies according to the type of use. Our results provide important insights for understanding the conditions that would precipitate rapid and wide uptake of greywater reuse in cities, and thereby make better use of limited water resources.

Supporter Profiling in Recycled Water Reuse: Evidence from Meta-Analysis

Recycled water is considered as a viable alternative water source, and its use is of great significance in dealing with the shortage of water resources. However, it is often rejected by the public during its promotion. To identity the common social attributes of proponents of recycled water, it is essential to study the profiled customers’ willingness to accept recycled water during the most difficult initial stage of promoting recycled water use projects. A meta-analysis was conducted in this study to deal with data concerning the influence of different social demographic factors on the public’s acceptance of recycled water use. Three steps of meta-analysis were mainly used in this paper. First, a random-effect model was used to measure the effect size of influencing factors, such as age, gender, and education. It was found that younger women were more likely to accept recycled water use than older men, and individuals with higher education were more willing to accept recycled water. Then, a cumulative meta-analysis showed that it was feasible to select young women with higher education as target profile customers in the initial stage of recycled water promotion. Finally, according to a meta-regression analysis, it was revealed that different research areas and selected model methods have important regulatory effects on the intention of the target population to use recycled water.

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.

Characterization of segregated greywater from Indian households: part A-physico-chemical and microbial parameters

Greywater has attracted global attention as a feasible alternative water source over the last few decades. Reuse and recycling of greywater is an economically viable and attractive option for meeting the future water demand. However, its treatment and reliable reuse continue to be based on conventional parameters such as BOD, COD, turbidity, suspended solids and pathogen level. The current investigative study focused on the characterization of segregated grey wastewater (greywater from bathroom, laundry and kitchen) from different economic classes of Indian households which included physical and chemical parameters, organics, nutrients, pathogens, heavy metals, oil and grease and surfactants. Apart from this, the data related to water consumption, frequency and products used for their daily activities were gathered using a questionnaire survey. The average water consumption among different household was found to be 108 L per capita per day. The maximum concentrations of organics such as BOD (678.6 ± 179 mg/L), COD (1507 ± 508 mg/L) and TOC (176.4 ± 131 mg/L) were found in kitchen wastewater. However, maximum concentrations of surfactants (14.02 ± 3.74 mg/L) were obtained in laundry wastewater. Faecal coliform concentration was more in the households which had inhabitants of children below 4 years. Statistical analysis revealed that the parameters monitored differ significantly between different economic classes. The present study showed that the characteristics of greywater highly depend on the wastewater source, household behaviour and activities. This study will be helpful to design a sustainable cost-effective treatment system, enabling greywater generated from different sources to be safely recycled and reused by households. Graphical abstract.

Consumers' Acceptance of Agricultural Fertilizers Derived from Diverted and Recycled Human Urine

Nitrogen and phosphorus are essential ingredients in fertilizers used to produce food. Novel methods are emerging for more efficiently sourcing these nutrients, one of which is to recover them from recycled human urine; once recovered, N and P can be redirected to fertilizer production. While the technology for creating human urine-derived fertilizer (HUDF) exists, implementing it at scale will depend on public acceptance. Thus, this study examined U.S. consumers' acceptance of HUDF across a range of applications and, in comparison, to other fertilizer types. Data were collected from a representative national sample, and analyses of variance with post-hoc comparisons were conducted to compare across fertilizer applications and types. A hierarchical regression was conducted to assess if demographics, psychological variables, and value orientations predict HUDF acceptance. Results suggest that HUDF and biosolid-based fertilizers are equally preferred and more strongly preferred than synthetic fertilizers. HUDF is not preferred as strongly as organic fertilizers. HUDF was deemed most acceptable when used on nonedible plants and least acceptable when used on crops for human consumption. Regression analysis revealed that judgments about risks and benefits were the strongest predictors of acceptance of UDF use. These results are promising for sanitation practitioners and regulators among others.

Reclaiming Suburbia: Differences in Local Identity and Public Perceptions of Potable Water Reuse

Urban water managers are increasingly interested in incorporating reclaimed water into drinking supplies, particularly in rapidly growing arid and semi-arid urban areas, such as the western United States. Northern Nevada is one location that is considering augmenting drinking water supplies with reclaimed water, a practice that is known as planned potable water reuse. Potable water reuse can expand water supply and reduce wastewater disposal. However, past studies have shown that the introduction of potable reclaimed water can be controversial and requires an understanding of public perceptions of the resource prior to implementation. This study explores the factors that influence whether or not respondents in northern Nevada express willingness to drink reclaimed water. We pay specific attention to the degree to which self-identification as an urban, suburban, or rural resident influences how people consider using treated wastewater for both potable and non-potable purposes. To address this, we conducted a survey to assess community perceptions of reclaimed water use and applications in northern Nevada in the spring of 2018. We find that years spent living in the home and a respondent being female are negative and significant predictors of being willing to drink reclaimed water, while having heard of reclaimed water before and self-identification as a suburban resident are positive and significant predictors. As the region becomes more developed, particularly in its growing suburbs, it is essential to understand the nature of the interests and concerns regarding water resources and the expanded use of reclaimed water.