Assessment of Potable Water Savings in Office Buildings Considering Embodied Energy

The objective of this article is to assess the potential for potable water savings in office buildings located in Florianópolis, southern Brazil. The embodied energy of four alternatives to reduce potable water demand, i.e., rainwater harvesting, greywater reuse, dual-flush toilets and water-saving taps, was also assessed. The analyses took into account the potable water end-uses for ten buildings. The potential for potable water savings by using rainwater, as well as, the rainwater tank sizing were estimated using computer simulation. As for greywater reuse, it was considered that greywater from lavatory taps could be treated and reused to flush toilets. The potential for potable water savings by using water-saving plumbing fixtures was estimated by considering the replacement of toilets and taps. In order to estimate the embodied energy in the main components, each system was dimensioned and embodied energy indices were applied. The main result is that the potential for potable water savings by using dual-flush toilets ranges from 21.6 % to 57.4 %; by reusing greywater, it ranges from 6.8 % to 38.4 %; by using rainwater, it ranges from 6.1 % to 21.2 %; by using water-saving taps it ranges from 2.7 % to 15.4 %. However, by considering the embodied energy, the average for the ten buildings indicates that dual-flush toilets are the best choice as it is possible to obtain water savings of 5.50 m³/month per GJ of embodied energy, followed, respectively, by water-saving taps, greywater reuse and rainwater usage. The main conclusion is that the assessment of embodied energy should be considered when evaluating potable water savings in buildings as it helps to identify the best alternatives to save more water while causing less environmental impact.     

Energy and Water in Arid Developing Countries: Saudi Arabia,a Case-study

In Saudi Arabia, where water resources are limited, the availability of energy resources, including petroleum, natural gas and electricity, helped in solving the challenge of satisfying rapid and substantial increases in water demand for drinking and industrial and agricultural purposes. Thirty-five major dual-purpose multi-stage flash distillation (MSF) and reverse osmosis (RO) desalination plants were constructed on the Red Sea and Gulf coast to produce drinking water. The process energy requirements for MSF and RO range between 19.5 and 38 kWh/m3, and 0.5 and 9 kWh/m3, respectively. The MSF plants produce about 20% of the total national electricity production. About 85 000 wells were drilled to satisfy the increasing irrigation water demands. The energy requirements to pump 1 m3 from wells range between 0.4 and 0.8 kWh. The adoption of advanced technologies is continuing to reduce power consumption and water demand to conserve energy and water, and to minimize negative impacts on the environment.     

Screening health risk assessment of micropullutants for indirect potable reuse schemes: a three-tiered approach.

Indirect potable reuse schemes are an important consideration in the sustainable management of scarce water resources. However, communities still hold real concerns about the potential health risks of micropullutants in recycled water entering their potable water supply. Microfiltration or ultrafiltration followed by reverse osmosis is currently the standard treatment technology for potable use of recycled water. Nevertheless, membranes are not 100% efficient in the removal of trace organic contaminants and the potential health risks of these micropullutants need to be assessed. The aim of this paper is to present a three-tiered approach for the preliminary assessment of micropullutants in recycled water. A risk quotient is calculated by comparing measured concentrations against benchmark values. Tier 1 corresponds to regulated chemicals; the maximum contaminant level in drinking water is used as benchmark value. Tier 2 corresponds to unregulated chemicals with toxicity information; slope factors or risk specific doses are used to calculate benchmark values. Tier 3 corresponds to unregulated chemicals without toxicity information. The "Threshold of Toxicological Concern" concept is used to calculate benchmark values. The characterization of chemicals of concern following reverse osmosis in a water reclamation plant and the application of the three-tiered approach for the evaluation of the potential health risks is presented.     

国外水循环再利用的实践和启示

通过对国外一些水循环再利用实践的研究，我们可以得到一些启示：水循环再利用是解决淡水资源紧张的有效途径：产权明晰是解决水资源市场化开发的必要条件；示范工程具有引导民间资本投资、培育水资源市场的外部经济性；节水意识、节水活动离不开经济手段的激励；稀缺是研发活动的推进剂，科学合理的水价是前提。     

Reusing Urban Wastewater—An Alternative and a Reliable Water Resource

ABSTRACT

Fundamental concepts of reusing urban wastewater as an alternative and a reliable source of water supply are discussed, along with the categories for water reuse, planning methodologies, wastewater reclamation technologies, and economics. The rational basis for integration of urban reclaimed water into water resources planning is proposed and the safe use of reclaimed water is evaluated. Special attention is paid to tertiary or advanced wastewater treatment systems that are capable of producing essentially pathogen-free effluent for a variety of uses such as irrigation of urban landscape, flushing of toilets served by dual plumbing systems in large commercial buildings, and groundwater recharge for eventual potable reuse. The motivating factors for wastewater reclamation and reuse are summarized and the costs of water reclamation projects are discussed with several examples. The integration of this alternative water supply into water resources planning is proposed and the safe use of reclaimed water is emphasized.     

澳门污水资源再生利用

介绍澳门水资源基本情况,分析澳门污水资源再生利用在节水、减污、降低供水成本、提高区域水资源安全等方面的价值,剖析污水资源再生利用在认识、土地、政策、管理、经验积累等方面的不利条件和政府积极推动、公众意识、新区建设等方面的有利因素,探讨澳门污水资源再生利用的用途、方式、处理工艺及水质标准、管理、价格、风险、规模等关键问题,提出澳门污水资源再生利用近期、中期和远期利用方案。     

Water Resources Management in Saudi Arabia and Water Reuse

ABSRTACT

The potential for water reclamation and reuse in Saudi Arabia are assessed by considering relationships among the technical, social, economic, and environmental parameters. Generally, the planning process for water reuse has focused on specific technological processes, however water reuse should be analyzed as part of a total hydrologic system to ensure the efficient transfer of wastewater reuse technology

To bring relationships into better focus, the application is developed with reference to Saudi Arabia, which provides an excellent opportunity for practicing water reuse. In this region, a limited water supply is used to satisfy municipal, industrial, agricultural, recreational and other beneficial uses. The economic and social trends are toward continued industrial development and urbanization. In this setting, water recycling through reuse is becoming a more and more important means of expanding water supplies to meet the growing demands for water for virtually all social, economic and environmental uses

Saudi Arabia is an arid country with very limited water resources and about 10 million people. The country covers some 2.2 million km², four-fifths of the Arabian Peninsula. It is the largest country in the world without a river or a lake, and thus it represents the ultimate in its need to use the limited water supplies wisely.     

Water management in Windhoek, Namibia.

For decades, the city of Windhoek in Namibia succeeded in stretching their limited potable water resources through strict water management, latterly including wastewater reclamation and direct potable reuse. An integrated approach was followed and proper policies were put in place. This was followed up with appropriate legislation, education, policing and technical and financial measures with the result that extreme water shortages were overcome even in times of severe droughts.     

Wastewater Reuse as Means to Optimize the Use of Water Resources in the West Bank

Abstract

The increase in demand for the limited raw water resources in the Palestinian Territories has led to the proposals for use of treated wastewater as one alternative for alleviating water shortages and for optimizing the use of water resources. Wastewater reuse is a multi-discipline and important element of water resources development. Wastewater usage releases high quality water for drinking and other purposes. Quantitative, economic, and social aspects related to wastewater reuse in the West Bank are discussed. Through analyses of the estimated cost and expected water quantities, the paper investigates the economic feasibility of wastewater reuse. Social acceptance is elicited by means of questionnaires, which have been applied to farmers and inhabitants in different areas of the West Bank. Wastewater reuse can compensate for about 10 percent of irrigated agriculture, which contributes 35 percent of the total value of the Palestinian agricultural sector. The paper presents an analysis of the main aspects of wastewater reuse and defines an approach to the beneficial use of wastewater as a component that should be considered in the strategy for the overall management of water resources in the Palestinian Territories.     

Modelling Sectorally Differentiated Water Prices - Water Preservation and Welfare Gains Through Price Reform?

This study simulates the economy-wide effects of introducing new water pricing systems in Israel. A Computable General Equilibrium (CGE) model, STAGE_W, is used that includes multiple water commodities produced from different water resources. The current water pricing scheme supplies potable water to municipalities at fees above the supply costs and subsidizes water delivered to the agricultural and the manufacturing sectors. Due to limited freshwater resources, climate change and population growth, water scarcity is an increasing problem in Israel. Therefore, pricing systems which lead to a more efficient allocation of water are intensely debated. This study analyzes two alternative pricing schemes under discussion in Israel: price liberalization, which unifies the prices for all potable water consumers at cost recovery rates, and marginal pricing that lifts the potable water price to the cost of desalination. Both schemes reduce water demand with limited economic costs. Price liberalization is the more favourable option from a national welfare perspective, while marginal pricing allows for larger water savings and, in the long run, independence from fresh water resources.     

Setting up microbiological water reuse guidelines for the Mediterranean.

Water reuse is a widespread practice in most Mediterranean countries. Some countries have no wastewater treatment facilities and direct reuse of raw wastewater is occurring while others have a well-established national reuse policy. Water reuse microbiological standards, when existing, significantly differ from one country to another. Some countries have adopted regulations close to the California's Water Recycling Criteria whereas other countries have chosen criteria based on the World Health Organisation (WHO) guidelines. California standards are technologically based requirements aimed at eliminating the presence of pathogens. The WHO guidelines relied on epidemiological evidences though few were available. Their revision on the basis of new epidemiological investigations and quantitative microbiological risk assessment (QMRA) provided by Blumenthal et al., together with added QMRA data, helped proposing Mediterranean guidelines. Acceptable annual risks related to bathing and potable water drinking were taken as benchmarks. This proposal is designed to protect individuals against realistic maximum exposures and to provide minimum and affordable requirements which should constitute the basis of water reuse regulations in every country of the region. Inadequacies of the actual knowledge do not allow a definitive position regarding the guideline limits; other scientific and technical basis are still required.     

九龙江流域水厂生产废水回用条件的初步研究

以九龙江原水为研究对象,从改善低浊水混凝条件优化净水工艺角度,对生产废水的回用条件和作用规律进行了研究。研究认为:回用具有适当含固率的生产废水可以改善水处理过程的混凝条件,节省投药量,节药率一般为10%～40%;存在改善混凝条件、节省投药量的最佳含固率和最佳混合水浊度范围,最佳含固率为0.1%～0.7%,最佳混合水浊度为60～400NTU;原水浊度是显著影响最佳含固率的因素。当原水浊度小于60NTU时,最佳含固率随原水浊度的升高而增加,当原水浊度大于60NTU时.最佳含固率随原水浊度的升高而降低,最佳混合水浊度表现出相同的规律;在生产过程中,建议以最佳混合水浊度控制生产废水的回用。     

Desalination of Seawater using Geothermal Energy to Meet Future Fresh Water Demand of Saudi Arabia

The future economy of the Middle East countries (GDP growth) depends on the availability of fresh water for domestic and agricultural sectors. Saudi Arabia, for example, consumes 275 L/day per capita of water that is generated from desalination process using 134 x 10⁶ kWh of electricity. With 6 % population growth rate, demand for fresh water from fossil fuel based desalination plants will grow at an alarming rate. It has been reported that Saudi Arabia’s reliance on fossil fuels to generate electricity and generate fresh water through desalination using the same energy source is economically and politically unsustainable. This may lead to destabilisation of the global economy. However, Saudi Arabia has large geothermal resources along the Red Sea coast that can be developed to generate power and support the generation of fresh water through desalination. The cost of fresh water can be further lowered from the current US$ 0.03/m³. Among the gulf countries, Saudi Arabia can become the leader in controlling CO₂ emissions and mitigating the impact on climate change and agricultural production. This will enable the country to meet the growing demand of food and energy for the future population for several decades and to reduce food imports.     

中关村软件园水循环利用规划方案

中关村软件园作为高新技术开发区,对园区内外的水务设施及环境均有较高的需求。为提高园区整体水安全方面的保障,编制水循环利用规划方案对园区整体具有十分重要的现实意义。通过分析园区内、外部市政自来水、市政再生水、自备井水、雨水以及自产再生水等各种水资源供需状况,规划从综合水循环的角度出发提出了2套总体方案供园区管理层进行决策。     

A knowledge-based control system for air-scour optimisation in membrane bioreactors

Although membrane bioreactors (MBRs) technology is still a growing sector, its progressive implementation all over the world, together with great technical achievements, has allowed it to reach a mature degree, just comparable to other more conventional wastewater treatment technologies. With current energy requirements around 0.6-1.1 kWh/m3 of treated wastewater and investment costs similar to conventional treatment plants, main market niche for MBRs can be areas with very high restrictive discharge limits, where treatment plants have to be compact or where water reuse is necessary. Operational costs are higher than for conventional treatments; consequently there is still a need and possibilities for energy saving and optimisation. This paper presents the development of a knowledge-based decision support system (DSS) for the integrated operation and remote control of the biological and physical (filtration and backwashing or relaxation) processes in MBRs. The core of the DSS is a knowledge-based control module for air-scour consumption automation and energy consumption minimisation.     

Emerging contaminants and treatment options in water recycling for indirect potable use.

Solutions to global water stress problems are urgently needed yet must be sustainable, economical and safe. The utilisation of alternative water sources like reclaimed municipal wastewater is one of the most obvious and promising options in integrated water resources management. Among the various beneficial uses of reclaimed wastewater Aquifer Recharge (AR) receives growing attention because it features advantages such as additional natural treatment, storage capacity to buffer seasonal variations of supply and demand as well as mixing with natural water bodies which promotes the acceptance of further uses, particularly indirect potable use. Major concerns about the safety of this exploitation route of an alternative water source are connected to microbial and chemical contaminants occurring in wastewater, among which are emerging trace organics like endocrine disrupters and pharmaceuticals. This paper reviews the current international debate about the relevance of emerging contaminants and technical mitigation options in water recycling for indirect potable use.     

Reuse of oil and gas produced water in south-eastern New Mexico: resource assessment,treatment processes,and policy

The Permian Basin of south-eastern New Mexico in the United States exemplifies the combination of rapidly expanding oil and gas production with freshwater shortages and aquifer stress. Reuse of saline produced water can provide a stable supply of water for drilling, fracturing and completion and minimize consumptive use of freshwater. We discuss water withdrawals and use by the oil and gas industry in this region, processes for reuse and recycling of produced water in place of freshwater, and operational and policy changes to help improve maximal use of all available water resources in this arid region.     

热电厂水资源综合利用

依据水循环经济的3R原则,对某热电厂水资源综合利用进行研究。通过对全厂用水、排水的分析与规划,得出水平衡图。结果表明,此项技术改造工程将提高热电厂的水循环利用率和用水效率,减少自来水的用量以及污水的排放量,可实现水、热、电联产,环境效益和社会效益得到明显提高。     

Visualising a Stochastic Model of Californian Water Resources Using Sankey Diagrams

This paper describes a novel approach to the analysis of supply and demand of water in California. A stochastic model is developed to assess the future supply of and demand for water resources in California. The results are presented in the form of a Sankey diagram where present and stochastically-varying future fluxes of water in California and its sub-regions are traced from source to services by mapping the various transformations of water from when it is first made available for use, through its treatment, recycling and reuse, to its eventual loss in a variety of sinks. This helps to highlight the connections of water with energy and land resources, including the amount of energy used to pump and treat water, the amount of water used for energy production, and the land resources that create a water demand to produce crops for food. By mapping water in this way, policy-makers can more easily understand the competing uses of water, through the identification of the services it delivers (e.g. sanitation, food production, landscaping), the potential opportunities for improving the management of the resource and the connections with other resources which are often overlooked in a traditional sector-based management strategy. This paper focuses on a Sankey diagram for water, but the ultimate aim is the visualisation of linked resource futures through inter-connected Sankey diagrams for energy, land and water, tracking changes from the basic resources for all three, their transformations, and the final services they provide.