Urban Water Reuse Research Articles

The Role of Scenario-Building in Risk Assessment and Decision-Making on Urban Water Reuse

Urban resilience and water resilience are both increasingly relying on urban non-potable water reuse under the context of the Climate Emergency, but sound risk assessment is lacking. Compared to the state of art, the proposed framework for health risk assessment and management of urban non-potable water reuse includes (i) an additional step for establishing the context and (ii) the risk identification step being extended to introduce a description of the activities from which the hazard exposure scenarios may be built. This novel scenario-building process allows for a clear and comprehensive risk description, assessment, and treatment. The model of risk management is structured around three primary components: the decision-makers, i.e., the municipal services and the population at risk (users and workers); data elements relevant for the risk management process (reclaimed water quality, hazards, hazardous events, sites where exposure can happen, exposure routes, and activities developed by the population at risk and their vulnerabilities); and the links between the decision-makers and these elements and between the elements themselves. Its application in a representative case study shows that the framework comprehensively guides decision-making and communication to relevant stakeholders. From this practical exercise, the main recommendations were derived for risk mitigation by the municipal risk manager and the park users.

Water Quality and the First-Flush Effect in Roof-Based Rainwater Harvesting, Part I: Water Quality and Soil Accumulation

Rainfall runoff may be captured and stored for later use, but the quality of this water can be detrimental in some uses without the use of appropriately designed first-flush diverters. The rainfall runoff water quality was measured on nineteen new small-scale and two aged commercial roofs located near high traffic highways. Roof coverings included asphalt shingles, sheet metal, clay tiles, and tar and gravel. Runoff samples were evaluated for polycyclic aromatic hydrocarbons (PAHs), phosphorus flame retardants (PFRs), and pyrethroid insecticides. Eighteen small-scale roofs were subjected to a range of simulated rainfall events, while natural runoff was sampled on the commercial roofs and one small-scale roof. Runoff was analyzed for pH, conductivity, turbidity, total suspended solids, boron, iron, copper, zinc, manganese, sodium adsorption ratio, nitrate-nitrogen, seventeen PAHs, tris(2-chloroethyl) phosphate, tris(1,3-dichloro-2-propyl)phosphate, bifenthrin, cypermethrin, and lambda-cyhalothrin. Samples from four natural storm events were also analyzed for total coliforms and Escherichia coli. In addition, soils below seventeen existing gutter downspouts were sampled to determine long-term pollutant accumulation. Atmospheric deposition was the main contributor of pollutants in the roof runoff. A majority of samples fell within the U.S. EPA guidelines for non-potable urban and agricultural water reuse. Trace levels of PAHs, PFRs, and insecticides were detected, but all detections were three orders of magnitude below the USGS health-based screening level benchmark concentrations. Results indicate that diverting the first flush, based on turbidity, total suspended solids, or conductivity, can improve the overall water quality and reduce the concentrations of PAHs in harvested rainwater. Downspout soil sampling showed potential for the long-term accumulation of PAHs at concentrations exceeding the minimum human-health risk-based screening levels at these high runoff-loading locations.

Impacts of multi-pollutants on sulfonamide antibiotic removal from water matrices using layered double hydroxide sorbents

Remediation of sulfamethoxazole (SMX) present in the aqueous environment requires the development of new advanced wastewater treatment technologies, crucial to reduce the toxicity of such pollutants to the environment, supporting urban water reuse. Continuously synthesised layered double hydroxides (LDH) have been applied as a sorbent material for the removal of SMX from water. No equilibrium uptake of SMX was observed from any water matrix. However, an unusual sorption/release behaviour of SMX was observed in the presence of Mg2Al-NO3-LDH, influenced by the characteristics of the water matrix. A maximum SMX removal percentage of 34.7% was reached within 10 min, from ultrapure water, followed by release of SMX back into solution over the following 24 h. Further, Mg2Al-NO3-LDH is shown to release NO3- into all water matrices. It is proposed that NO3- disrupts the SMX-LDH interactions, resulting in release of SMX from the LDH. No initial SMX sorption was observed onto Mg2Al-NO3-LDH when wastewater effluent was the water matrix, likely due to competition for sorption sites on the LDH with multiple pollutants, including metals and additional anionic nutrients, present in the wastewater. This work illustrates the potential for relationships between the sorbent material and water matrix interactions on pollutant sorption behaviour. In addition, the findings highlight the importance of conducting removal experiments at realistic environmental conditions to ensure development of suitable sorbent materials for pollutant remediation.

Water Reuse, a Sustainable Alternative in the Context of Water Scarcity and Climate Change in the Lisbon Metropolitan Area

Water scarcity is a driver for society to rethink water management and change the paradigm of use to a fit-for-purpose approach—i.e., separating potable water for human consumption (drinking, cooking or personal hygiene) from all non-potable uses that do not require the same quality level. In this context, urban water reuse is a relevant tool for municipalities and metropolitan areas when dealing with pressure on water resources, among several alternative water sources that can be considered in a site-specific and integrated manner. Through the available literature and specific case studies in the Lisbon Metropolitan Area, this paper explores the benefits and barriers of water reuse and intends to support local authorities in including water reuse in their water management strategies. To the best of our knowledge, this is the first paper focusing on Portugal and the Lisbon Metropolitan Area that globally examines governance, economic, legislative and social aspects regarding water reuse and presents specific implementation examples covering potable and non-potable as well as direct and indirect reuse.

Opportunities for Water Reuse Implementation in Metropolitan Areas in a Complex Approach with an LCA Analysis, Taking Warsaw, Poland as an Example

Water shortages are currently becoming a more global than local issue. This paper aims to demonstrate a complex, universal urban water reuse system, allowing for a reduction of freshwater withdrawal. Opportunities for improvement were analyzed in the categories of municipal services: power and heat production, greenery irrigation, landscaping, street and public transport fleet cleaning. Technical possibilities were coupled with current international legislative requirements. Two scenarios for universal, complex water reuse systems in the municipal area were evaluated, including all essential city services. Results of the case study show that ozonation and filtration of treated wastewater should be sufficient to obtain the desired water quality for urban purposes. Current legislation mainly addresses agricultural water reuse, so their requirements should be adjusted to assess the water quality needed for other applications. When water is used in public spaces, constant monitoring for the presence of pathogens should be maintained due to the risk of human exposure. A life cycle assessment was conducted to evaluate the environmental impacts associated with the topic of water transportation in urban areas, which is infrequently considered in such studies. Two scenarios including different means of transport were compared. It was shown that with constant daily operation, it is necessary to build an independent water network, since the environmental impact of water delivery by tank lorries increases substantially.

Combined process of chemically enhanced sedimentation and rapid filtration for urban wastewater treatment for potable reuse

ABSTRACT The objective of this study is to propose a new post-treatment of effluents from Upflow Anaerobic Sludge Blanket (UASB) using rapid filtration, aiming at the production of water for potable reuse. The final quality of the effluent produced by the treatment using gravel, sand, clinoptilolite and activated carbon associated with disinfection was evaluated by physical chemical analysis, heavy metals and persistent organic contaminants. Experiments were carried out in jar test, filter operation time, evaluation of the efficiency using peracetic acid and free chlorine as disinfectant and all results were statistically analysed. The best conditions were those using 20 mg/L of ferric chloride and natural pH of the effluent (≈ 7.0), which resulted in less reagent consumption. The use of intermediate fund discharges made it possible to obtain approximately 91% of recovered water efficiency. The effluent treated under these conditions showed DOC <2.0 mg/L, COD <1.0 mg/L, BOD <1.0 mg/L, turbidity <1.0 NTU, TSS <1.0 mg/L, ammonia <0.1 mg/L, total phosphorus <0.1 mg/L and surfactants <0.1 mg/L. The disinfection process with free chlorine and PAA allowed the total inactivation of faecal coliforms and total coliforms. The treatment using rapid filtration with disinfection by chlorine reached the appropriate level for urban, environmental, industrial and indirect potable water reuse.

Analysis and Countermeasures of Membrane Pollution in Urban Water Reuse

Analysis and Countermeasures of Membrane Pollution in Urban Water Reuse

The Water-Energy-Food-Ecosystem Nexus in the Mediterranean: Current Issues and Future Challenges

The Mediterranean is an area where the balance between water demand and abstractions vs. water availability is often under stress already, as demonstrated here with the Water Exploitation Index. In this work, model estimates on how different proposed measures for water resources management would affect different indicators. After a review of the current water resources status in the Mediterranean and the definition of indicators used in this study, aspects interlinked with water in the Water-Energy-Food-Ecosystems Nexus are briefly discussed, focusing on problems linked with water scarcity and depletion of groundwater resources as well as with climate change projections. Subsequently, the proposed measures for water efficiency are detailed—irrigation efficiency, urban water efficiency, water reuse and desalination—that might be effective to reduce the growing water scarcity problems in the Mediterranean. Their effects that result from the LISFLOOD model, show that wastewater reuse, desalination and water supply leakage reduction lead to decreased abstractions, but do not affect net water consumption. Increased irrigation efficiency does decrease consumption and reduces abstractions as well. We deduct however that the current envisaged water efficiency measures might not be sufficient to keep up with the pace of diminishing water availability due to climate change. More ambition is needed on water efficiency in the Mediterranean to keep water scarcity at bay.

Perspective on Land Treatment and Wastewater Reuse for Agriculture in the Western United States

The practice of irrigation with municipal wastewater has evolved from avoidance of surface water pollution to beneficial reuse of water and nutrients for crop production. The ability of the soil to filter out pollutants and pathogens has been documented, such that groundwater quality is not degraded where recycled water to irrigate crops used for human consumption. The example of successful practice of the Castroville project in Monterey County, California illustrates safe reuse of recycled water for crop growth, marketing of crops grown into the fresh produce market, and groundwater protection. Impediments to the future more widespread reuse of recycled water for agricultural irrigation are also discussed. Many of the same technological advancements that have supported the development of modern agricultural water reuse projects have also improved the feasibility of various competing urban water reuse applications. The effects from increasing water scarcity has also had an impact on the quality and quantity of water available for agricultural water reuse projects. The historical practice of developing centralized and regional wastewater treatment facilities near a suitable surface water discharge location may need to be modified for better consideration of agricultural irrigation in integrated water resources planning.

Institutional challenges and stakeholder perception towards planned water reuse in peri-urban agriculture of the Bengal delta

The indirect, unplanned use of urban wastewater by peri-urban farmers in developing countries poses a severe risk to the environment and the farmers. Planned water reuse could contribute substantially to the irrigation water demand in peri-urban agriculture and minimize the risk. However, implementing such practice requires a thorough evaluation of stakeholder's perception and the scope within the existing organizational structures. This paper aims to assess the level of awareness, perception, and willingness of different stakeholders toward current practices and the prospect of urban water reuse in Khulna City - one of the most vulnerable cities located in the southwest of Bangladesh due to the consequences of rapid climate changes in the Bengal delta. Also, institutional arrangements and their functioning were analyzed to understand the current sectoral performance. One questionnaire with 385 respondents from the urban area, 32 in-depth interviews and one focus group discussion with farmers in the peri-urban area, and ten interviews with key informants from the government and non-government organization was conducted. Results indicate an overall positive attitude among major stakeholder groups toward planned water reuse for peri-urban agriculture. More than half of the citizens (53%) are willing to pay for the treatment of wastewater and majority of the farmers (66%) are willing to pay for the supply of better-quality irrigation water. However, the public sector responsible for wastewater collection and treatment requires adjustment in rules and regulations to implement planned water reuse. Interrelated factors such as lack of transparency and coordination, shifting responsibilities to other organizations, lack of required resources need to be addressed in the updated rules and regulations. Strategies to enforce current regulations and align all stakeholders are also crucial for collection and treatment of wastewater and its subsequent use for crop production.

A New Approach to the Optimal Design of a Reclaimed Urban Water Reuse System

It is strategically important to optimize the pipe network used for reclaimed urban water reuse. A large and complex system model is developed, with the minimum total annual cost of the pumping station and pipe engineering as objective functions, the head loss in the divided pipe segment as the coupling constraint, the economic flow velocity and the optimal diameter of a standard pipe as feasible domain constraints, and the design head and diameter of the pipe as decision variables. The problem is solved by combining the ratio of the discrete enumeration of the design head to the decomposition-dynamic programming aggregation of the large-scale system. This strategy can solve the problem of the optimal pipe diameter in each section of the pipe network engineering under a fixed design head of the pressurized pumping station. On this basis, the annual cost of reclaimed water reuse pipe network engineering is compared under the different design heads of the pressurized pumping stations, allowing the optimal design scheme for reclaimed water reuse pipe network engineering to be obtained. At the same time, the optimal design head of the pressurized pumping station and the optimal pipe diameter of each section can be identified. This can provide a theoretical reference for the optimal design of urban and rural water pipe networks.

Effect of Water Irrigation from Different Sources on Soil and Plant Properties in Qalyubiya Governorate, Egypt

Particularly in dry regions, the scarcity of high-quality fresh water has heightened the importance of urban water re-use. The aim of this research is to evaluate the different of water resources in Qalyubiya Governorate, Egypt, for irrigation purposes. Its bounded by latitudes 30o 25′ N and longtitudes 31o 13′ E, 17 meters high above sea level. Taking into consideration the effect of used water on soil properties and accumulation of some elements in plants. Representative water, soil and plant samples were collected from Abu El-Manja canal and Iskandar drain sites, Qalyub area. The results indicated that soil salinity increased due to the application of drainge water in irrigation, howevere Rice plants diminshed the salinity effect. It is observed that the concentration of Pb, Zn and Cu increased in Onion and rice plants either irrigated by canal water or drainage water. No significance differnent in soil physical properties were observed in both study sites.

Governing Non-Potable Water-Reuse to Alleviate Water Stress: The Case of Sabadell, Spain

The world will experience an estimated 40% freshwater supply shortage by 2030, converting water scarcity into one of the principal global challenges that modern society faces. Urban water reuse is recognized as a promising and necessary measure to alleviate the growing water stress in many regions. The transformation to widespread application of water-reuse systems requires major changes in the way water is governed, and countries such as Spain already find themselves involved in this process. Through the systematic assessment of the city of Sabadell (Spain), we aim to identify the main barriers, opportunities and transferable lessons that can enhance governance capacity to implement systems for non-potable reuse of treated wastewater in cities. It was found that continuous learning, the availability and quality of information, the level of knowledge, and strong agents of change are the main capacity-building priorities. On the other hand, awareness, multilevel network potential and implementing capacity are already well-established. It is concluded that in order to undertake a widespread application of water-reuse practices, criteria examining water quality according to its use need to be developed independently of the water’s origin. The development and implementation of such a legislative frame should be based on the experience of local water-reuse practices and continuous evaluation. Finally, the need for public engagement and adequate pricing mechanisms are emphasized.

The influence of context and perception when designing out risks associated with non-potable urban water reuse

ABSTRACTPerceptions and cognitive bias in relation to reuse water can influence the responses to risk and reward. Much has been written on community perspectives and risk perceptions with regard to recycled water for non-potable use. This paper is distinct in that it focuses on the scheme proponents and those involved in designing and delivering schemes. An analysis of five case studies in Australia across a range of diverse settings revealed that the levels of treatment for various end-uses were in excess of the Australian Guidelines for Water Recycling. The evidence shows that the water industry has a fairly narrow view when identifying risks, and has an insurance type response to mitigating the risk. The overarching drivers for this are either the mitigation of the perceived risk associated with using reuse water, or the lack of an adaptive response to changes in the circumstances.

Comparative life cycle sustainability assessment of urban water reuse at various centralization scales

Population growth and urbanization lead to increasing water demand, putting significant pressure on natural water sources. The rising amounts of domestic wastewater (WW) in urban areas may be treated to serve as an alternative water source that may alleviate this pressure. This study examines sustainability of utilizing reclaimed domestic wastewater in urban households for toilet flushing and garden irrigation. It models a city characterized by water scarcity, using a coal-based electricity mix. Four approaches were compared: (0) Business-as-usual (BAU) alternative, where the central WW treatment plant effluent is discharged to nature; (1) central WW treatment and urban reuse of the effluent produced; (2) semi-distributed greywater treatment and reuse, at cluster scale; (3) Distributed greywater treatment and reuse, at building scale. Environmental life cycle assessment (LCA), social LCA (S-LCA), and life cycle costing (LCC) were applied to the system model of the above scenarios, with seawater desalination as the source for potable water. System boundaries include water supply, WW collection, and treatment facilities. Analytical hierarchy process (AHP), a multi-criteria decision analysis (MCDA) methodology, was integrated into the life cycle sustainability assessment (LCSA) framework as a means for weighting sustainability criteria through judgment elicitation from a panel of 20 experts. Environmentally and socially, the two distributed alternatives perform better in most impact categories. Socially, semi-distributed (cluster scale) reuse is somewhat advantageous over the fully distributed alternative (building scale), due to the benefits of community engagement. Economically, the cluster-level scenario is the most preferable, while the building-scale scenario is the least preferable. A hierarchical representation of the problem’s criteria was constructed, according to the principals of AHP. Each criterion was weighted and those of extreme low importance were eliminated, while maintaining the integrity of the experts’ judgments. Weighted and aggregated sustainability scores revealed that cluster level reclamation, under modeled conditions, is the most sustainable option and the BAU scenario is the least sustainable. The other two alternatives, centralized and fully distributed reclamation, obtained similar intermediate scores. Distributed urban water reuse was found to be more sustainable than current practice. Different alternative solutions are advantageous in different ways, but overall, the reclamation and reuse of greywater at the cluster level seems to be the best option among the three reuse options examined in this assessment. AHP proved an effective method for aggregating the multiple sustainability criteria. The hierarchical view maintains transparency of all local weights while leading to the final weight vector.

A comparative social life cycle assessment of urban domestic water reuse alternatives

The social benefits and impacts of four alternative approaches to urban domestic non-potable water reuse were compared: (1) central wastewater treatment, no urban reuse. Reclaimed water is discharged to nature; (2) central wastewater treatment and urban reuse of the wastewater treatment plant’s tertiary effluent; (3) semi-distributed greywater treatment and reuse, at cluster scale (8 residential buildings); (4) distributed greywater treatment and reuse, within each apartment building. The impacts of the four aforementioned approaches to water reuse on three relevant stakeholders were investigated: public, community, and consumer. A hierarchical structure of impact categories and sub-categories under these stakeholder groups was established. Expert judgment elicitation was used to attribute weights to the social criteria, through an analytical hierarchy process (AHP). AHP is an established multi-criteria decision analysis method, based on series of pairwise comparisons. It was also used to evaluate impact intensities for both quantitative and qualitative social indicators. All expert judgements were integrated into an overall weight vector, and a comprehensive social score was calculated for each compared scenario. Public commitment to water saving was ranked as the most important factor in assessing the social impacts of urban domestic reuse, with a weight of 29.6%. Two sub-categories of the community category ranked second: urban landscape and community engagement (12.6% and 12.0%, respectively). The two distributed alternatives are advantageous over the other two approaches in terms of water saving and urban landscape. The semi-distributed alternative has a significant benefit of community engagement, which the other three lack. The business-as-usual (BAU, no reuse) scenario scored highest in the categories: public equality, consumer health concerns, and consumption habits. Final scores for the compared scenarios indicate that central reuse is somewhat more socially beneficial than no urban reuse, but the two distributed alternatives are far better. In social life cycle assessment (SLCA) often quantitative and qualitative criteria/indicators exist side by side and their harmonious integration is challenging. The challenge arising is twofold: quantifying qualitative indicators and homogenizing all indicator evaluations into a uniform comparable scale. Both tasks were achieved in this study using the AHP. The AHP also successfully served as a platform for participatory processes of eliciting expert judgments regarding criteria weights and may be very useful for stakeholder participation in any social assessment. Regarding the case study—distributed urban water reuse was found to be socially beneficial, both in terms of promoting public commitment to conservation of natural water resources and in advancing community engagement.

Performance of nanofiltration and reverse osmosis after membrane bioreactor for urban source-separated urine treatment and water reuse

Performance of nanofiltration and reverse osmosis after membrane bioreactor for urban source-separated urine treatment and water reuse

Assessing Location and Scale of Urban Nonpotable Water Reuse Systems for Life-Cycle Energy Consumption and Greenhouse Gas Emissions.

Nonpotable water reuse (NPR) is one option for conserving valuable freshwater resources. Decentralization can improve distribution system efficiency by locating treatment closer to the consumer; however, small treatment systems may have higher unit energy and greenhouse-gas (GHG) emissions. This research explored the trade-off between residential NPR systems using a life-cycle approach to analyze the energy use and GHG emissions. Decentralized and centralized NPR options are compared to identify where decentralized systems achieve environmental advantages over centralized reuse alternatives, and vice versa, over a range of scales and spatial and demographic conditions. For high-elevation areas far from the centralized treatment plant, decentralized NPR could lower energy use by 29% and GHG emissions by 28%, but in low-elevation areas close to the centralized treatment plant, decentralized reuse could be higher by up to 85% (energy) and 49% (GHG emissions) for the scales assessed (20-2000 m3/day). Direct GHG emissions from the treatment processes were found to be highly uncertain and variable and were not included in the analysis. The framework presented can be used as a planning support tool to reveal the environmental impacts of integrating decentralized NPR with existing centralized wastewater infrastructure and can be adapted to evaluate different treatment technology scales for reuse.

Energy consumptions and associated greenhouse gas emissions in operation phases of urban water reuse systems in Korea

Water reuse systems have been widely implemented across the globe as a solution to water shortage and freshwater contamination. Ongoing controversies regarding supposedly high energy cost and the lack of sufficient data to support benefits of water reuse are delaying further expansion of implementation of water reuse systems in South Korea. In order to clarify the ambiguity regarding the energy demand and provide an unbiased comparison between the water reuse alternatives and the conventional water supply system, energy consumptions and greenhouse gas emissions in operation phases of different water reuse facilities and the conventional water supply system were examined. The average total energy consumption and the greenhouse gas emission of the conventional process were calculated to be 0.511 kWh/m3 and 0.43 kgCO2e/m3, respectively. Centralized wastewater reuse systems had prohibitively high energy consumptions (1.224–1.914 kWh/m3) and greenhouse gas emissions (0.72–0.83 kgCO2e/m3). The decentralized wastewater reuse systems, greywater reuse and rainwater harvesting systems, all used for non-potable purposes, had comparable or higher energy demands than the conventional process (0.246–0.970 kWh/m3 after adjustment), although estimated greenhouse gas emissions from these processes were lower than the conventional process (0–0.33 kgCO2e/m3 after adjustment). Considering the hidden environmental benefit (0.357 kWh/m3) from reduction of contaminant release, the energy demand of greywater reuse drops far below that of the conventional system, suggesting that decentralized water reuse is the key to an energy-efficient water management with minimal impact on climate change.

Risk Analysis Approach to Rainwater Harvesting Systems

Urban rainwater reuse preserves water resources and promotes sustainable development in rapidly growing urban areas. The efficiency of a large number of urban water reuse systems, operating under different climate and demand conditions, is evaluated here on the base of a new risk analysis approach. Results obtained by probability analysis (PA) indicate that maximum efficiency in low demanding scenarios is above 0.5 and a threshold, distinguishing low from high demanding scenarios, indicates that in low demanding scenarios no significant improvement in performance may be attained by increasing the storage capacity of rainwater harvesting tanks. Threshold behaviour is displayed when tank storage capacity is designed to match both the average collected volume and the average reuse volume. The low demand limit cannot be achieved under climate and operating conditions characterized by a disproportion between harvesting and demand volume.