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

Many countries' water resources are limited in both quantity and quality. While engineering solutions can now safely produce recycled and desalinated water from non-potable sources at a relatively low cost, the general public is sceptical about adopting these alternative water sources. Social scientists, policy makers and technical experts need to better understand what is causing this lack of acceptance by the general population and how acceptance levels for recycled and desalinated water can be increased. This study is the first to conduct a comparative analysis of knowledge, perceptions, and acceptability, and determine segments of residents who are more open-minded than the general population toward the use of recycled and desalinated water. The Australian population once perceived desalinated water as environmentally unfriendly, and recycled water as a public health hazard. The general level of knowledge about these two concepts as potential water sources has historically been low. After nearly five years of serious drought, accompanied by severe water restrictions across most of the country, and subsequent media attention on solutions to water scarcity, Australians now show more acceptance of desalinated water for close-to-body uses, and less resistance to recycled water for garden watering and cleaning uses. The types of people likely to be strong accepters of the two alternative water sources are distinctly different groups, and can be reached through different media mixes. This finding has significant implications for policy makers and water practitioners.     

Evaluation of Lake Modification Alternatives for Lake Sihwa, Korea

After the construction of an embankment at the Bay of Sihwa in Korea, a lake of 56.5 km² surface area and 330 million m³ volume was created. Because of rapid socioenvironmental changes and the lowering of water quality in Lake Sihwa, various external measures have been proposed and some of them are being implemented. In this paper, we examine two alternatives for in-lake modification: one alternative is zoning of the lake by constructing two submerged dams and the other is channeling of the lake through reclamation. Water quality modeling was conducted for both alternatives to assess their effects. Results of the modeling revealed that the reduction of the lake size through two different approaches, when accompanied with other external measures, would improve the water quality, but to different degrees. The zonation is expected to improve the freshwater quality up to the level supplying 45 million m³ of water per year for agricultural use. The quality of channeled water would be inappropriate for agricultural use, but suitable for outdoor activities such as recreation or fishing regardless of reclamation plans considered.     

Increasing urban water self-sufficiency: new era, new challenges

Urban water supplies are traditionally based on limited freshwater resources located outside the cities. However, a range of concepts and techniques to exploit alternative water resources has gained ground as water demands begin to exceed the freshwater available to cities. Based on 113 cases and 15 in-depth case studies, solutions used to increase water self-sufficiency in urban areas are analyzed. The main drivers for increased self-sufficiency were identified to be direct and indirect lack of water, constrained infrastructure, high quality water demands and commercial and institutional pressures. Case studies demonstrate increases in self-sufficiency ratios to as much as 80% with contributions from recycled water, seawater desalination and rainwater collection. The introduction of alternative water resources raises several challenges: energy requirements vary by more than a factor of ten amongst the alternative techniques, wastewater reclamation can lead to the appearance of trace contaminants in drinking water, and changes to the drinking water system can meet tough resistance from the public. Public water-supply managers aim to achieve a high level of reliability and stability. We conclude that despite the challenges, self-sufficiency concepts in combination with conventional water resources are already helping to reach this goal.     

Evaluation of alternative water sources for commercial buildings: A case study in Brisbane,Australia

Commercial buildings are central to cities and contribute significantly to the urban demand for natural resources, including freshwater. Green building benchmarking tools include more efficient water use as key indicator of sustainability. This paper explores options for substituting mains drinking water with an alternative, non-potable water source on a fit for purpose basis. The research findings are based on a monitoring study of a commercial building in Brisbane, Australia that is harvesting rainwater for meeting non-potable water demand. The results demonstrated that the system is only achieving moderate reliability in meeting demand due to operational problems. The case study analysis has highlighted the need to include validation and monitoring to ensure the system is operating as per design intent. The paper also investigates the potential of other local, non-potable water sources for high-rise commercial buildings, in particular air conditioning condensate and groundwater inflow to a basement wet well. The paper concludes by comparing the advantages and disadvantages of different local water sources which highlights the need to undertake a site specific investigation to identify a suitable alternative water source, which considers O&M complexity and the capacity of facilities management.     

Nitrous oxide emissions from wastewater treatment and water reclamation plants in southern California

Nitrous oxide (N?O) is a long-lived and potent greenhouse gas produced during microbial nitrification and denitrification. In developed countries, centralized water reclamation plants often use these processes for N removal before effluent is used for irrigation or discharged to surface water, thus making this treatment a potentially large source of N?O in urban areas. In the arid but densely populated southwestern United States, water reclamation for irrigation is an important alternative to long-distance water importation. We measured N?O concentrations and fluxes from several wastewater treatment processes in urban southern California. We found that N removal during water reclamation may lead to in situ N?O emission rates that are three or more times greater than traditional treatment processes (C oxidation only). In the water reclamation plants tested, N?O production was a greater percentage of total N removed (1.2%) than traditional treatment processes (C oxidation only) (0.4%). We also measured stable isotope ratios (δN and δO) of emitted N?O and found distinct δN signatures of N?O from denitrification (0.0 ± 4.0 ‰) and nitrification reactors (-24.5 ± 2.2 ‰), respectively. These isotope data confirm that both nitrification and denitrification contribute to N?O emissions within the same treatment plant. Our estimates indicate that N?O emissions from biological N removal for water reclamation may be several orders of magnitude greater than N?O emissions from agricultural activities in highly urbanized southern California. Our results suggest that wastewater treatment that includes biological nitrogen removal can significantly increase urban N?O emissions.     

The effect of information on public acceptance – The case of water from alternative sources

This study aims to provide conclusive evidence that information about water from alternative sources increases public acceptance. We conducted an experiment with 1000 Australian respondents asking them about their acceptance of recycled and desalinated water for a range of purposes under two conditions: 1) no information provided and 2) information about the production process provided. Results indicate that – both for desalinated and recycled water – the stated likelihood of use increases significantly if people are provided with information about the production process. This has major implications for public policy makers indicating that providing factual information (as opposed to persuasive campaigns) will increase public support of water augmentation projects.     

Securing water for people, crops, and ecosystems: New mindset and new priorities

A fundamentally new approach to water and human development will be needed during this new century if we are to secure sufficient freshwater to meet the needs of some 9 billion people while at the same time protecting the critical ecosystem services upon which the human economy depends. Signs of unsustainable water use — including falling water tables, shrinking lakes, and the drying up of rivers and streams — are widespread and spreading. In many regions, greater modification and appropriation of freshwater systems for human purposes will yield greater costs than benefits and create the risk of irreversible losses of species and ecosystem services. A new mindset is needed to guide water use and management in this new century, one that views the human water economy as a subset of nature's water economy. Living within nature's limits will require that societies satisfy the basic needs of people and ecosystems before non-essential water demands are met. It will require on the order of a doubling of water productivity. And it will require stronger institutions to encourage equitable sharing of water to alleviate tensions within and between countries.     

Water management initiatives in sugarcane molasses based distilleries in India

Molasses based alcohol distilleries in India are one of the most polluting industries; in addition, they are high consumers of raw water. Growing scarcity of high quality freshwater as well as stringent regulatory standards is compelling these units to explore appropriate water management options. This paper provides an overview of the water use and effluent treatment status in Indian distilleries and the challenges faced by this sector. Practices adopted by progressive Indian distilleries to minimize freshwater use are illustrated through case studies. Further, the R&D focus pertaining to wastewater treatment and disposal is also summarized.     

An assessment of Spain's Programa AGUA and its implications for sustainable water management in the province of Almería, southeast Spain

Spain's Programa AGUA was proposed in 2004 as a replacement for the Spanish National Hydrological Plan and represented a fundamental policy shift in national water management from large inter-basin water transfers to a commitment to desalination. Twenty-one desalination facilities are planned for six provinces on the Spanish Mediterranean coast to supplement their water needs. These include the province of Almería that for the last 30 years has endured a net water abstraction overdraft leading to serious reservoir depletion and groundwater imbalances. Rising water use is a result of increasing demand to support irrigated agriculture (e.g. greenhouse horticulture) and for domestic needs (e.g. rapid urban growth and tourism development), which has led observers to question Almería's long-term water sustainability. Desalinated water alone is unlikely to be sufficient to make up these water deficits and water-users will have to accept a move to full-price water recovery by 2010 under the European Union (EU) Water Framework Directive of which Spain is a signatory. Anticipated water efficiencies resulting from higher water tariffs, increasing water reuse and water infrastructure improvements (including inter-basin transfers), in conjunction with increasing use of desalinated water, are expected to address the province's current water overdraft. However, Almería will need to balance its planned initiatives against long-term estimates of projected agricultural and domestic development and the environmental consequences of adopting a desalination-supported water future.     

Efficient water use in industries: cases from the Indian agro-based pulp and paper mills

Agro-based pulp and paper mills in India are one of the most polluting industries; in addition, they are high consumers of raw water. Growing scarcity of high quality freshwater as well as stringent regulatory standards is compelling these units to explore appropriate water management options. Based on data obtained through a questionnaire survey and plant visits, this work provides an overview of the water use and effluent treatment status in Indian agro-residue and recycled pulp and paper mills. The challenges faced by this sector are reviewed and practices adopted by progressive units to minimize freshwater use are illustrated through case studies.     

Water resources issues of small island developing states

The water resources of most small island developing states (SIDS) are often very limited and require special consideration to ensure that they are developed and managed in a sustainable manner. Many small islands, typically located in the humid tropics, have no surface water resources and rely on limited groundwater resources in the form of thin freshwater lenses. The exposed location of small islands makes them particularly vulnerable to natural disasters such as cyclones, floods and droughts. Pollution from population centres and from agricultural and other activities is an increasing problem. This article provides an overview of the water resources of small islands, and the main problems and issues related to water resources. Some suggested solutions, based on practical experiences, are offered for water resource assessment and monitoring programmes, and water resource development. Water resource policy, planning and management issues are also addressed, and suggested approaches for resolving some of the major water resource problems presented.     

Sustainable water future with global implications: everyone's responsibility

The current use and management of freshwater is not sustainable in many countries and regions of the world. If current trends are maintained, about two-thirds of the world's population will face moderate to severe water stress by 2025 compared to one-third at present. This water stress will hamper economic and social development unless action is taken to deal with the emerging problems. The Comprehensive Assessment of the Freshwater Resources of the World, prepared by the United Nations and the Stockholm Environment Institute, calls for immediate action to prevent further deterioration of freshwater resources. Although most problems related to water quantity and quality require national and regional solutions, only a global commitment can achieve the necessary agreement on principles, as well as financial means to attain sustainability. Due to the central and integrated role played by water in human activities, any measures taken need to incorporate a wide range of social, ecological and economic factors and needs. The Assessment thus addresses the many issues related to freshwater use, such as integrated land and water management at the watershed level, global food security, water supply and sanitation, ecosystem requirements, pollution, strengthening of major groups, and national water resource assessment capabilities and monitoring networks. Governments are urged to work towards a consensus regarding global principles and guidelines for integrated water management, and towards their implementation in local and regional water management situations. The alternative development options available to countries facing water stress, or the risk thereof, needs to be considered in all aspects of development planning.     

A historical perspective of river basin management in the Pearl River Delta of China

Three innovations in water and soil conservancy technology in the Pearl River Delta of South China, i.e., dike building, land reclamation, and dike-pond systems, were examined from a historical perspective. They were found to best reflect local farmers' efforts to cope with the challenges of various water disasters and to build a harmonious relationship with the changed environment. These technologies were critical to the agricultural success and sustainability over the past 2000 years, and reflected local farmers' wisdom in balancing land use and environmental conservation. Imprudent use of a new agricultural technology could damage the environment, and could disturb the human-environment relationship, as evidenced by the more frequent flooding that followed inappropriate dike building and premature reclamation. It is suggested that as the urbanization and industrialization process in the delta region continues, the kind of thinking that made the water and soil conservancy sustainable needs to be incorporated into the design of similar technologies for water use and river basin management today.     

Review of socio-economic drivers of community acceptance and adoption of decentralised water systems

The aim of this paper is to highlight key social and economic drivers crucial to understanding community acceptance and adoption of decentralised water systems. The review focused on social science literature pertaining to alternative forms of household water, with an emphasis on research examining decentralised water acceptance. Researchers consistently reported that most communities were open to alternative water sources for domestic applications; however, this was highly dependent upon the level of personal contact with the water. Acceptance and adoption of alternative water technology, such as decentralised systems, was influenced by risk perception, water culture, and threat perception. Motivational drivers were also identified as potentially influencing adoption of decentralised systems. A clear limitation of the literature was found to be an over-reliance on measuring people's intentions to adopt alternative water systems and building a conceptual understanding of acceptance solely on hypothetical water supply scenarios. Further, within the social science literature there appears to be a skewing towards focusing on acceptance of centralised alternative water, such as recycled and desalinated water systems. Although there are some research outcomes that are generalizable to the decentralised water context, it is clear that there is a significant gap in the knowledge base of social drivers specific to the acceptance of decentralised water systems and the factors contributing to its widespread use. It is recommended that future research focus on examining public attitudes relevant to decentralised water systems, as well as adoption behaviours among current users of these systems. This will assist in developing policies specific to domestic decentralised water use.     

Water rights and legal pluralism: four contexts for negotiation

Increasing water scarcity is increasing pressure on water management institutions, particularly in the area of water rights. A common response is to formalise water tenure, one of several options for securing access and resolving conflicts concerning water allocation. This article looks at four contexts where negotiation, self-governance and concepts of legal pluralism may help improve water resource management. Existing users and potential new users need to negotiate before water resources are developed. Users can participate in forums with authority to solve basin management problems through self-governance. Negotiated water transfers offer an alternative to water acquisition by expropriation.     

Car wash wastewater reclamation. Full-scale application and upcoming features

Recent features on car wash wastewater reclamation and results obtained in a full-scale car wash wastewater treatment and recycling are reported. The technique employed comprises a new flocculation-column flotation (FCF), sand filtration and final chlorination. Water usage and savings audits (20 weeks) showed that almost 70% reclamation was possible, and less than 40 L of fresh water per wash was attained. Wastewater and reclaimed water were fully characterized by monitoring chemical, physicochemical and biological parameters. Results were discussed in terms of reclamation aesthetic quality (water clarification and odour), health (pathological) and chemical (corrosion and scaling) risks. Noteworthy, this work showed a high count of fecal and total coliforms both in the wastewater and in the treated water, making the need of a final disinfection mandatory. The cost-benefit analysis shows that, for a car wash wastewater reclamation system in Brazil, at least 8 months were needed for the FCF-SC equipment amortization, when considering a demand over 30 washes per day. It is believed that the discussions on car wash wastewater reclamation criteria may assist alerting wash cars units and institutions to create laws in Brazil and elsewhere.     

Sustainable Rainwater Catchment Systems for Micronesian Atoll Communities

Atoll island communities rely on rainwater catchment systems (RWCS) as a primary method of storing freshwater. However, stored freshwater can be depleted during times of drought, requiring importation of water to sustain community living. To maintain adequate water supply under future climatic conditions, the functioning of RWCS for atoll communities must be analyzed and optimal designs must be adopted. In this study, a quantitative analysis of stored daily water volumes is provided for atoll islands within the Federated States of Micronesia (FSM), with Nikahlap Island, Pakein Atoll, and a generic island in western FSM used as representative cases. Using a daily water balance model for the RWCS, baseline conditions are simulated for the 1997‐1999 time period, during which an intense El Niño‐induced drought occurred, and a sensitivity analysis is performed to quantify the influence of RWCS features on water system outputs, whereupon an optimal RWCS design using existing infrastructure is analyzed. Results indicate the strong influence of catchment area, system efficiency, and storage capacity on water volumes and the depletion of water during dry seasons and drought periods using current RWCS infrastructure. Adequate storage can be maintained during a major drought if unused RWCS features are employed and if minimal rationing is adopted. Study results provide water resource managers and government officials with valuable data for consideration in water security measures.     

The US freshwater supply shortage: Experiences with desalination as part of the solution

Parts of the USA are facing impending shortages of freshwater. One proposed solution is the construction of desalination plants to turn seawater into freshwater. Although seawater desalination plants are widely used in the Middle East, especially Saudi Arabia, there are few desalination plants in the USA. In 2003, Tampa Bay Water built the largest desalination plant in North America. Persistent operating problems and escalating costs have caused the utility to re-evaluate its reliance on the seawater desalination plant as part of a long-term regional water supply strategy. In addition, environmental effects of the plant are uncertain. Advances in reverse osmosis technology have significantly reduced desalination costs. However, desalination of seawater is still more expensive than other freshwater supply sources and demand management measures. With time and research, seawater desalination may prove to be a sustainable, cost-effective source of new freshwater supplies, especially if plants are coupled with renewable energy sources. Until then, the development of small-scale groundwater desalination plants, the re-use of water, water conservation, and a more efficient allocation of water through higher prices and rising block rates will be important strategies in meeting growing water demand. Moreover, it is important to improve the coordination between water supply planning and land use planning as populations continue to increase.     

Using system dynamics to model water-reallocation

Improving the efficiency of water allocation has long been recognised as a key problem for the water resources management decision-makers. However, assessing the efficacy of management decision is difficult due to the complexity and interconnectivity of water resource systems. For this reason, it is vital that robust modelling approaches are employed to deal with the feedback loops inherent in the water resource systems. Whilst many studies have applied modelling to various aspects of water resource management, little attention has been given to innovations in modelling approaches to deal with the modelling challenges associated with improving decision-making. The aim of this study is to apply a System Dynamics modelling approach to improve the efficiency of water allocation incorporating a myriad of irrigation system constraints. The system dynamic approach allows the different system components to be organised as a collection of discrete objects that incorporate data, structure and function to generate complex system behaviour. Through the application of a system dynamic approach, a robust model (named the Economical Reallocating Water Model (ERWM)) was developed which was used to examine the options of re-allocating water resources that minimize the water cost all over an irrigated agricultural area. The EWRM incorporated a wide range of complexities likely to be encountered in water resource management: surface and ground water sources, water trading between sources, system constraint such as maximum ground water pumping, rates, maximum possible trading volumes and differential water resource prices. Two hypothetical systems have been presented here as an example. The results show that the System Dynamics approach has a significant advantages in estimating and assessing the outcomes of alternative water management strategies through time and space.     

Contribution of Wastewater Treatment Plant Effluents to Nutrient Dynamics in Aquatic Systems: A Review

Excessive nutrient loading (considering nitrogen and phosphorus) is a major ongoing threat to water quality and here we review the impact of nutrient discharges from wastewater treatment plants (WWTPs) to United States (U.S.) freshwater systems. While urban and agricultural land uses are significant nonpoint nutrient contributors, effluent from point sources such as WWTPs can overwhelm receiving waters, effectively dominating hydrological characteristics and regulating instream nutrient processes. Population growth, increased wastewater volumes, and sustainability of critical water resources have all been key factors influencing the extent of wastewater treatment. Reducing nutrient concentrations in wastewater is an important aspect of water quality management because excessive nutrient concentrations often prevent water bodies from meeting designated uses. WWTPs employ numerous physical, chemical, and biological methods to improve effluent water quality but nutrient removal requires advanced treatment and infrastructure that may be economically prohibitive. Therefore, effluent nutrient concentrations vary depending on the particular processes used to treat influent wastewater. Increasingly stringent regulations regarding nutrient concentrations in discharged effluent, along with greater freshwater demand in populous areas, have led to the development of extensive water recycling programs within many U.S. regions. Reuse programs provide an opportunity to reduce or eliminate direct nutrient discharges to receiving waters while allowing for the beneficial use of reclaimed water. However, nutrients in reclaimed water can still be a concern for reuse applications, such as agricultural and landscape irrigation.