Distributed Water Infrastructure for Sustainable Communities

Distributed water infrastructure (located at the community or the household level) is relatively untried and unproven, compared with technologies for managing urban water at higher (e.g. regional) levels. This work presents a review of currently available options for distributed water infrastructure and illustrates the potential impact of their deployment through a number of indicative infrastructure strategies. The paper summarises the main categories of both centralised and decentralised water infrastructure, covering all three flows (water supply, wastewater and drainage) and their integration through recycling and reuse. The potential impact of the identified infrastructure options for urban water management is examined. The desirability of the strategies examined, is dependent on (case specific) constraints to urban development, including for example regional or local water resource availability, treatment plant capacity, cost of upgrading infrastructure, potential for (distributed) energy (micro) generation and climatic changes (and other non-stationary processes). The results are presented and discussed. It is concluded that there is currently a significant potential for a range of improvements in urban water management which could result from the context-aware deployment of a portfolio of technological infrastructure options. It is also suggested that there are trade-offs between water use, energy use and land use, and these have an equilibrium point that is associated with the technological state-of-art. At a given technological state-of-art, further reductions in water savings signify increase either energy consumption (for high-tech solutions) or land use (for low-tech solutions). The strategies’ evaluation indicates however, that until this equilibrium point is reached there can be significant gains in all three aspects. After this equilibrium, improvements in one aspect inevitably signify costs in others. The choice of desired trade-off then depends on the specific constraints of the problem at hand.     

The application of economic-engineering optimisation for water management in Ensenada, Baja California, Mexico.

Mathematical optimisation is used to integrate and economically evaluate wastewater reuse, desalination and other water management options for water supply in Ensenada, Baja California Mexico with future levels of population and water demand. The optimisation model (CALVIN) is used to explore and integrate water management alternatives such as water markets, reuse and seawater desalination, within physical capacity constraints and the region's water availability, minimising the sum of economic costs of water scarcity and operating costs within a region. The modelling approach integrates economic inputs from agricultural and urban water demand models with infrastructure and hydrological information, to identify an economically optimal water allocation between water users in Ensenada. Estimates of agricultural and urban economic water demands for year 2020 were used. The optimisation results indicate that wastewater reclamation and reuse for the city of Ensenada is the most economically promising alternative option to meet future water needs and make water imports less attractive. Seawater desalination and other options are not economically viable alone, but may have some utility if combined with other options for the Ensenada region.     

Strategien und Potenziale zur Energieoptimierung bei der Wasserwiederverwendung

The energy and materials derived from treating sewage are becoming increasingly important worldwide and are thus progressively considered resources rather than a disposal problem. This is also apparent in the growing interest in recycling water from municipal wastewater for both non-potable and potable purposes, supplementing the drinking water supply in the latter case. However, the energy consumption of about 0.9–1.8 kWh/m³, required to recycle drinking water, is not insignificant. Due to the lack of national as well as international standardized regulatory specifications for recycled water quality, very different technical solutions for potable water reuse have been deployed worldwide. Therefore, energy-saving measures often can only be applied to internal operational optimizations and the achievable savings are rather limited. Strategies for integrated energy recovery, the increased use of anaerobic biological processes and combined heat and power (CHP) for water recycling are hence very promising. These provide opportunities for internal power provision and therefore options to reduce the specific energy requirements for potable water reuse to well below 1 kWh/m³, despite the necessary treatment processes. However, the greatest potential for energy-efficient water recycling is at the regional planning level. Recycling water is only attractive where local freshwater resources are insufficient or there is a dependency on imported water, and it is the significantly more cost-effective option than the treatment of brackish or sea water.     

Centralised urban wastewater reuse: what is the public attitude?

Public support is crucial for successful implementation of wastewater reuse projects. This paper analyses the findings of a questionnaire-type survey (256 participants) conducted to determine the attitude of Israeli urban public towards possible urban reuse options. The paper summarises the support/objection to 13 reuse options and the correlation between support and environmental awareness and perceptions. Results show that a high proportion of the participants supported options perceived as low-contact, such as irrigation of public parks (96%), sidewalk landscaping (95%) and use in the construction industry (94%), while higher-contact reuse options found less support (e.g. commercial launderettes, 60%). No correlation was found between biographical characteristics and support (education, gender, income, age). Based on the results, public campaigns in Israel should focus on disseminating information regarding wastewater treatment technologies, discuss health related issues, highlight the positive economic impact of water reuse and generate a positive public opinion, as these factors tend to influence individuals to support reuse projects.     

Utilising integrated urban water management to assess the viability of decentralised water solutions

Cities worldwide are challenged by a number of urban water issues associated with climate change, population growth and the associated water scarcity, wastewater flows and stormwater run-off. To address these problems decentralised solutions are increasingly being considered by water authorities, and integrated urban water management (IUWM) has emerged as a potential solution to most of these urban water challenges, and as the key to providing solutions incorporating decentralised concepts at a city wide scale. To incorporate decentralised options, there is a need to understand their performance and their impact on a city's total water cycle under alternative water and land management options. This includes changes to flow, nutrient and sediment regimes, energy use, greenhouse gas emissions, and the impacts on rivers, aquifers and estuaries. Application of the IUWM approach to large cities demands revisiting the fundamental role of water system design in sustainable city development. This paper uses the extended urban metabolism model (EUMM) to expand a logical definition for the aims of IUWM, and discusses the role of decentralised systems in IUWM and how IUWM principles can be incorporated into urban water planning.     

Emerging approaches to integrated urban water management: cluster scale application.

Integrated Urban Water Management (IUWM) seeks to extend Water Sensitive Urban Design to a total water cycle approach that includes reuse of wastewaters. This paper investigates the appropriateness of environmental technologies for application at a cluster scale in IUWM. Many environmental technologies are economically or physically unsuited to use on a municipal or unit scale. Cluster scale is a middle ground that will allow such environmental technologies to achieve full potential. The concept of cluster scale and the application of environmental technologies at this scale are discussed along with some examples of suitable technologies.     

Efficient water market mechanisms to cope with water scarcity

Water markets are increasingly being relied upon as an instrument to reallocate water between competing users under conditions of water scarcity, and within an environment of fully committed water resources. Without such a reallocation new irrigation developments cannot take place and economic developments will be forgone to the detriment of rural communities. There is therefore a need for continued development of a water market mechanism to ensure that this reallocation process can take place as efficiently as possible, and to alleviate the socio-economic impact of water scarcity. Since markets are still emerging around the world it is important to learn from operating markets. This paper discusses the operational mechanism of a water exchange in Victoria, Australia, and analyses the outcome of the first five years of operation.     

A Framework for Wastewater Reuse in Jordan: Utilizing a Modified Wastewater Reuse Index

Pressing water scarcity in Jordan rapidly increases the demands of marginal water resources for the agricultural sector. Water management studies reveal that no single source could fully solve the nation??s water shortage and many integrated actions are needed to ensure water availability, suitability and sustainability. Yet, among these options treated wastewater has the largest potential to augment water supply in the near future, thereby narrowing the gap between available freshwater and total demand. Indeed, treated wastewater could be a valuable source for irrigation in the agricultural sector and an increasing percentage of irrigated areas, especially in the Jordan Valley, are currently using treated wastewater. With a fast growing population and expansion of the irrigated areas to meet food demand, the pressure on water resources in Jordan remains of imminent importance. Hence, an urgent call to analyze the current and potential role of treated wastewater seems justified. Under the umbrella of the project on the Sustainable Management of Available Water Resources with Innovative Technologies (SMART) funded by the German Federal Ministry for Education and Research in Germany, an investigation has been carried out in the Jordan Valley to estimate the current wastewater reuse quantities and the potential to increase its utility for agricultural production. In general, the reuse as percentage of total treatment is applied for national and international comparisons. Yet, this index is of limited use for policy decisions as it does not reflect potentialities of wastewater use. Therefore, this study introduces a wastewater reuse index (WRI) that reflects the actual proportion of wastewater reused from the total generated wastewater. We found that the WRI in Jordan steadily increased from 30% in 2004 to 38 in 2007. Efficient use of treated wastewater requires the application of new technologies in Jordan like dwellings connected to the sewer system, decentralization of treatment plants to rural and urban settlements and prevention of high evaporation rates from stabilization ponds.     

Understanding community receptivity to water re-use: Ku-ring-gai Council case study.

This social research project investigated community receptivity to using rainwater and greywater as alternative domestic water sources. It was focused in the Ku-ring-gai local government area in northern Sydney, and involved a household questionnaire followed by community leader interviews and resident focus groups. Trends, such as a prolonged drought and increasing population, compound the current crisis and concern facing Sydney's available water supply. Substitution of domestic potable water has been promoted as part of the solution. The research results revealed that community receptivity was highest for external uses, such as watering gardens and flushing toilets, and progressively decreased with increasing personal contact. Receptivity to greywater reuse fell more rapidly with the community believing there was a higher health risk associated with its use. Gender and cultural background were revealed as significant variables and give insight into the design of strategies to target these demographic groups. This evidence provides a reliable stocktake of current receptivity revealing that the community has good awareness and positive association with water reuse for many household activities. This now needs to be harnessed through programs targeted at developing skills, resources and motivation for new water reuse practices and technologies across diverse social groupings.     

热电厂中水回用深度处理技术与国内应用进展

综述了我国中水深度处理工艺的发展历程、相关工艺在国内电厂的主要研究与应用情况及其主要问题与控制策略。石灰混凝法是热电厂中水回用的第二代处理工艺,应用广泛;双膜法及全膜法具有更高的污染物去除效率,已成为目前热电厂中水回用的主流深度处理工艺。膜污染是膜法深度处理工艺的限制因素,膜污染形成机制与控制策略研究成为中水回用领域的研究热点和难点。随着水处理技术及设备的发展,一些新型的材料、技术和设备也逐渐推广应用于热电厂的中水深度处理;未来城市中水将成为热电厂的第一水源,膜法将成为中水深度处理与回用的最关键工艺,其预处理和深度处理工艺将实现多样化与高效化的发展。     

再生水灌溉水处理工艺及灌溉 技术要求研究

再生水灌溉是解决水资源短缺的有效途径之一。结合目前再生水回用的必要性和紧迫性,对 再生水处理和灌溉工艺的确定进行了简要的分析,从建设目的、水质标准、工艺流程方面进行了阐述 和研究。最后,就污水处理相关技术与工艺、再生水灌溉的技术要求与标准以及再生水灌溉的管理和 监测等方面,对再生水灌溉提出了相应的新型再生水处理工艺和技术要求。     

Intended process water management concept for the mechanical biological treatment of municipal solid waste

Accumulating operational experience in both aerobic and anaerobic mechanical biological waste treatment （MBT） makes it increasingly obvious that controlled water management would substantially reduce the cost of MBT and also enhance resource recovery of the organic and inorganic fraction. The MBT plant at Gescher, Germany, is used as an example in order to determine the quantity and composition of process water and leachates from intensive and subsequent rotting, pressing water from anaerobic digestion and scrubber water from acid exhaust air treatment, and hence prepare an MBT water balance. The potential of, requirements for and limits to internal process water reuse as well as the possibilities of resource recovery from scrubber water are also examined. Finally, an assimilated process water management concept with the purpose of an extensive reduction of wastewater quantity and freshwater demand is presented.     

Review on the fate of organic micropollutants in wastewater treatment and water reuse with membranes

A brief review of the fate of micropollutants in membrane-based wastewater treatment due to sorption, stripping, biological degradation/transformation and membrane separation is discussed, to give an overview of these technologies due to the growing importance for water reuse purposes. Compared with conventional activated sludge treatment (CAS) micropollutant removal in membrane bioreactor (MBR) is slightly improved due to complete suspended solids removal and increased sludge age. For discharge to sensitive receiving waters advanced treatment, such as post-ozonation or activated carbon adsorption, is recommended. In water reuse plants nanofiltration (NF) and reverse osmosis (RO) efficiently reject micropollutants due to size exclusions as well as electrostatic and hydrophobic effects reaching potable quality. To remove micropollutants fully, additionally post-ozone or the addition of powdered activated carbon (PAC) have to be applied, which in parallel also reduce NDMA precursors. The concentrate has to be treated if disposed to sensitive receiving waters due to its high micropollutant concentration and ecotoxicity potential. The present review summarizes principles and capabilities for the most important membrane-based applications for wastewater treatment, i.e. porous membranes in MBRs (micro- or ultrafiltration) and dense membrane applications (NF and RO) for water reuse.     

A Decision Support Methodology for Integrated Urban Water Management in Remote Settlements

This paper describes a decision support methodology for the selection of a wastewater treatment system based on integrated urban water management principles for a remote settlement with failing septic systems. Thirty-two service and treatment technologies options were considered, these included: (i) conventional gravity sewerage, (ii) common effluent drainage, (iii) community sewage treatment plant based on various technology options (lagoon treatment, Living Machine®, sequencing batch reactor, membrane biological reactor, rotating biological contactor, recirculating textile filter, extended aeration) with and without urine separation, greywater diversion or treatment and reuse at household scale. The options were assessed using a framework that considered technical, economic, environmental and social factors relevant to the local community and associated stakeholders (water utility, government agencies) and tools such as engineering design, life cycle assessment and multi-criteria analysis for evaluation of overall sustainability. Adoption of a systems approach allowed the identification of benefits and trade-offs among stakeholders creating opportunities for adoption of more innovative treatment options and maximisation of the sustainability of the service. The treatment option that maximised the social, environmental and economic benefits for the settlement consisted of individual households adopting greywater treatment, storage and reuse, urine separation and a community wastewater treatment plant with recirculating textile filter technology. This solution provided the required sanitation, increased the sources of water supply to residents, satisfied environmental regulator requirements, minimised nitrogen discharge to waterways and provided an option for beneficial reuse of urine for neighbouring farmers at a cost and management needs acceptable to the water utility.     

超滤技术在中国油田采出水深度处理中的应用

在油田开采过程中,油田采出水中含有大量油类物质,综述了以超滤为核心的技术在油田采出水深度处理中的应用;根据不同的水质要求,可采取多种组合工艺处理并回用,有效缓解了水资源短缺问题,是保障油田高效开采和资源化利用的重要途径,为最终实现可持续发展奠定基础。     

Water reuse for irrigation from waste water treatment plants with seasonal varied operation modes.

Irrigation periods are usually limited to vegetation periods. The quality requirements for treated wastewater for disposal and for reuse are different. The reuse of water for irrigation allows partly the reuse of the wastewater's nutrients (N and P). Outside the irrigation period the water must be treated for disposal, thus nutrient removal is often required in order to avoid detrimental effects on the receiving surface water body. Only wastewater treatment plants with different operation modes for different seasons can realise these requirements. The nitrification is the most sensitive biological process in the aerobic wastewater treatment process. At low water temperatures the nitrifying bacteria need several weeks to re-start full nitrification after periods without NH4-removal. Therefore it is necessary to develop options for waste water treatment plants which allow a fast re-start of the nitrification process. Based on theoretical considerations and computer simulations of the activated sludge treatment process, one possibility for implementing a wastewater treatment plant with different seasonal operation modes is evaluated.     

Performance of UASB septic tank for treatment of concentrated black water within DESAR concept.

Separation of wastewater streams produced in households according to their origin, degree of pollution and affinity to a specific treatment constitutes a starting point in the DESAR concept (decentralised sanitation and reuse). Concentrated black water and kitchen waste carry the highest load of organic matter and nutrients from all waste(water)streams generated from different human activities. Anaerobic digestion of concentrated black water is a core technology in the DESAR concept. The applicability of the UASB septic tank for treatment of concentrated black water was investigated under two different temperatures, 15 and 25 degrees C. The removal of total COD was dependent on the operational temperature and attained 61 and 74% respectively. A high removal of the suspended COD of 88 and 94% respectively was measured. Effluent nutrients were mainly in the soluble form. Precipitation of phosphate was observed. Effective sludge/water separation, long HRT and higher operational temperature contributed to a reduction of E. coli. Based on standards there is little risk of contamination with heavy metals when treated effluent is to be applied in agriculture as fertiliser.     

Ecosystem Service Impacts of Urban Water Supply and Demand Management

Utilities face the challenge of enhancing long-term water security while minimising undesirable economic, social and environmental impacts of supply and demand management options. This paper provides an example of how the ecosystem services concept can be used to enumerate and organise broad impacts of water supply options. A case study of Adelaide, South Australia, is used to examine costs and benefits associated with different sources of water and source-water mix scenarios. Ecosystem service impacts are estimated using estimates from the literature. Seven water supply and demand management options are considered for Adelaide: 1) the River Murray, 2) Mt. Lofty Ranges catchments, 3) wastewater reuse, 4) desalination, 5) stormwater harvesting, 6) groundwater and 7) water conservation. The largest costs are associated with sourcing water from conservation measures such as water restrictions on outdoor watering estimated at $1.87/kL. Salinity damage costs associated with residential uses are estimated at up to $1.54/kL. Salinity damage costs of wastewater reuse were estimated at $1.16/kL. The largest benefit is coastal amenity services associated with stormwater harvesting and treatment estimated at $1.03/kL. Results show that there is a trade-off between financial costs and ecosystem services impacts with source-water mix scenarios with the highest ecosystem services cost having the lowest financial O&M cost and vice versa. This highlights the importance of taking ecosystem services into account when evaluating water supply options.     

The role of biofilms in water reclamation and reuse.

Biofilms play a major role in many water reclamation and reuse technologies. Normally, wherever there is water, a support surface and nutrients available, a biofilm will form. In some cases, this may result in problems for the water treatment system, due to biofouling or the growth of pathogenic or other unwanted microbes, but more frequently, the biofilm serves a very useful purpose by biodegrading organic contaminants in the water or by converting unwanted inorganic materials into harmless ones. Biofilms are commonly found associated with membrane reactors and filtration systems used in water reclamation and reuse systems, and are often a critical component. They are also found in soils where they may impact water injection or removal systems, or in situ bioremediation. Knowledge of the way biofilms form, how they grow and how to control them is critical for effective design and operation of many water reclamation facilities. This paper explores the modes of formation and growth of biofilms, modern methods for exploring the structure and function of biofilms, and how to control their growth. This paper also presents details on our development of microelectrode sensor arrays for continuous soil pore water quality monitoring.     

居住小区给排水规划的有关问题探讨

通过对目前各城市新建居住小区现状的分析与思考 ,提出居住小区给排水设计中应实行分质按量供水 ,以实现水的循环再利用 ;结合居住小区的建筑布局 ,统筹兼顾 ,合理规划小区给排水系统 ,综合布置小区管网 ;应体现以人为本的设计理念 ,树立绿色、环保、节能的设计意识 ;还应推广应用新产品、新材料、新技术 ;建立居住小区给排水信息网络管理系统 ,实现小区的智能化管理