Large-scale Seawater Desalination Research Articles

Performance study of a pilot-scale low-temperature multi-effect desalination plant

A 30t/d low-temperature multi-effect evaporation seawater desalination (LT-MED) system was designed based on the mathematical model, and the corresponding pilot device was constructed in Tianjin, China. Whole-process tests were carried out, and the effects of key operating parameters, including motive steam pressure, maximum operating temperature, temperature difference, spray density, non-condensing gas extraction method, and steam ejector flow, on desalination performance were analyzed. Results showed that the device successfully met product water design requirements; total dissolved solids were less than 5mg/L. Water production initially increased as motive steam pressure increased, then stabilized when pressure exceeded 21% of the design value. Water production reached its maximum when heat transfer temperature difference and spray density ranged from 3°C to 4°C and from 240L/(mh) to 300L/(mh), respectively. Unlike in parallel mode, water production increased by 3.64% when vacuum pumping was operated in series mode. Water production and gain output ratio increased, and system energy consumption reduced when a thermo-vapor compressor was introduced. The results provide a useful reference for the design of other large-scale seawater desalination systems.

대규모 해수담수화 플랜트에서의 전처리공정 비용 분석

A cost analysis method for pretreament processes of a large scale seawater desalination plant was considered using a cost estimation model, WaTER (Water Treatment Estimation Routine). This model is based on cost functions of U.S. EPA to conduct economic analysis of water treatment facilities. A virtual seawater desalination plant which has pretreatment production capacity of 100,000 m3 per day was chosen as a model plant. Dual media filtration and microfiltration systems were compared as pretreatment process, and the following reverse osmosis process was modeled. As a result, microfiltration showed a price competitiveness in condition of operating with reverse osmosis process by reducing the loads of water treatment and membrane cleaning despite it`s high annual cost.

Salt recovery from brine generated by large-scale seawater desalination plants

Water shortages in the Middle East and North Africa (MENA) region countries mandate the installation of large-scale desalination plants. Concentrate management requires properly operated cost-effective technologies to reduce the environmental impacts arising from brine discharge. Significant improvement in economics may be obtained by the recovery of chemicals from brines. This study addresses the management of modular brine streams generated from large-scale reverse osmosis desalination plants with microfiltration and nanofiltration (NF) as pretreatment stages. Appropriate salt recovery schemes have been identified and analyzed from the performance and environmental points of view. The economics of salt recovery schemes from NF and reverse osmosis (RO) brine based on evaporation ponds, brine evaporator and membrane crystallizer (MCr) are analyzed and compared. Phased application of the salt recovery program is considered. The results indicate that using NF as pretreatment and adopting salt recovery schemes provide higher water recovery in addition to producing valuable products. The adoption of MCr has high prospects for application in salt recovery from desalination brine. Increasing the capacities of salt recovery systems offers both technical and economic merits.

Acid and multivalent ion resistance of thin film nanocomposite RO membranes loaded with silicalite-1 nanozeolites

The incorporation of NaA nanozeolites into thin film composite (TFC) reverse osmosis (RO) membranes has been found to elevate water permeability, but the unfavorable acid and multivalent ion sensitivity of NaA limits the application of the thin film nanocomposite (TFN) membranes for seawater desalination. To overcome these drawbacks, the chemically stable silicalite-1 nanozeolite was incorporated into the skin layer of the RO composite membrane via interfacial polymerization. In this paper, the resulting membrane was characterized with outstanding chemical stability (acid and multivalent cation tolerance) compared with the NaA mixed membrane. Additionally, silicalite-1 showed better capacity to enhance membrane permeability than NaA, which can be explained by larger channel pores and a higher water diffusion rate in silicalite-1. This investigation indicates that the silicalite-1 mixed membrane has great potential in large-scale seawater desalination because of its excellent permeability and chemical stability.

Quantifying the actual benefits of large-scale seawater desalination in Israel

Israel's master plan for integrating large-scale seawater desalination plants within the national water supply system was drafted in the year 1997. This master plan sought not only to minimize the costs of these additional water sources, inter alia through plant siting, economies of scale, and maximizing utilization of existing infrastructures, but also to maximize their benefits. Some of the benefits, particularly those resulting from higher product water quality requirements, justified, on a cost-benefit ratio basis, corresponding slight increases in the costs of desalinated water production. At the end of 2011, desalinated seawater was supplied continuously and reliably into the regional and national water grids from three large plants, Ashkelon, Palmachim, and Hadera, at the rate of about 300 million m3/year. This quantity represented about 42% of all the potable water inputs into these grids (other inputs were groundwater and Sea of Galilee water). In three years, by the end of 2014, two additional large plants, at Soreq A and Ashdod, and an expanded Palmachim plant will be producing an additional 300 million m3/year. The paper revisits the benefits foreseen in the original desalination master plan, quantifies them on the basis of actual data accumulated over the past year and some new studies on the economic effects of water shortages and water supply quality, compares them with past expectations, and projects them to 2014, when about 80% of grid supplied water will be desalinated seawater.

Changing perception of the value of urban water in Australia following investment in seawater desalination

Recent climatic changes and population growth throughout Australia have highlighted the need for more diverse and climate-independent water sources to be introduced to secure local and regional water supplies. Australia is the world’s driest inhabited continent and the unpredictable climate means that the Australian population generally requires up to five times the water storage than does an equivalent population in, for example, Europe. Although 85% of its people live within 50 km of the coast, the country has only begun to consider large-scale seawater desalination within the past seven years. The total potable and industrial water consumption in Australia is estimated to be around 50,000 ML/d. In 2005, the total capacity of installed desalination for potable and industrial use was about 0.6% (300 ML/d). This is expected to increase more than seven times to 4% (1,900 ML/d) by 2015. In response to the growth in desalination capacity, the Australian Government has invested $20 m in desalination research over five years and established the National Centre of Excellence in Desalination Australia (NCEDA), a consortium of 14 universities and research organisations. The NCEDA has 33 research projects in progress and has completed a Pilot Scale Test Facility and Desal Discovery Centre to educate schoolchildren in Perth.

The Future of Seawater Desalination: Energy, Technology, and the Environment

In recent years, numerous large-scale seawater desalination plants have been built in water-stressed countries to augment available water resources, and construction of new desalination plants is expected to increase in the near future. Despite major advancements in desalination technologies, seawater desalination is still more energy intensive compared to conventional technologies for the treatment of fresh water. There are also concerns about the potential environmental impacts of large-scale seawater desalination plants. Here, we review the possible reductions in energy demand by state-of-the-art seawater desalination technologies, the potential role of advanced materials and innovative technologies in improving performance, and the sustainability of desalination as a technological solution to global water shortages.

Water import and transfer versus desalination in arid regions: GCC countries case study

The scarcity of water resources and the increasing gaps between demand and available supply in the Gulf Cooperation Council (GCC) countries is a major challenging issue facing the development sectors. GCC countries have extremely dry climates with rare rainfall, high evaporation rates and limited non-renewable groundwater resources. At present all GCC countries except Oman fall in the critical water scarcity category which is about 500 m3 of renewable water/cap/year. In addition, governmental policies with regard to increasing the level of food self-sufficiency through subsidies and other incentives, have contributed to a major expansion in and unrestricted use of non-renewable groundwater resources. This coupled with a lack of defined policies and strategies geared toward optimizing and managing the scarce water supplies within the GCC region, have contributed to wasteful and uneconomic practices, as well as to the inefficient mining of non-renewable supplies. To meet the present and future water demands of the region the available options are limited to either long distance water transfer and import from other countries or investing in large scale seawater desalination installations. In this paper the economical, technical, sustainability and the political criteria affecting the two alternatives have been evaluated. Economic analysis revealed that the cost of long distance water transfer can escalate to more than 0.83 US$ per cubic meter. When sustainability considerations are taken into account this figure may reach up to 2.35 US$ per cubic meter. While these figures were competitive with the cost of seawater desalination 20 y ago, the situation has been recently shifted in favor of seawater desalination which dropped from 5.5 US$ in 1979 to less than 0.55 US$ in 1999 using the RO technology. It is concluded that sustainable development of GCC countries will depend in the future on large scale desalination. This fast growing technology should replace or at least be considered a viable alternative to presently planned water transfer projects. Expanding desalination capacity in the next 20 y will be possible by building new plants or upgrading the existing facilities in GCC countries. This process, however, will require high economic investment.

A brief review of desalination in Australia in 2010

Recent climate changes and population growth throughout Australia have highlighted the need for more diverse and climate-independent water sources. Australia is the world's driest inhabited continent and the unpredictable climate means that the Australian population generally requires up to five times the water storage than does an equivalent population in the UK. Although 85% of its people live within 50 km of the coast, the country has only begun to consider large-scale seawater desalination within the past five years (Crisp, 2009). The total potable and industrial water consumption in Australia is around 50,000 ML/d (Hoang, 2009). In 2008, the total volume of water desalinated for potable and industrial use was about 0.6% (300 ML/d) and this is expected to increase more than seven times to 4% by 2013. A brief review of current (2010) desalination capacity in Australia follows and includes major seawater plants, brackish water and wastewater reuse.

Analytical solutions for brine discharge plumes on a sloping beach

Large scale seawater desalination plants are operated along the coasts and dispose of their brine waste stream by discharging into the sea. As the need for desalinated seawater is steadily increasing, more new desalination plants are planned to be constructed. If desalination plants are closely clustered together along the coastlines, the adverse environmental impacts of the brine effl uent discharges from plants such as these are strongly inter-dependent. A farfi eld mathematical model for continuous brine discharges from two desalination plants on a uniformly sloping beach is presented. The analytical solutions are illustrated graphically to study the interaction of two brine discharge plumes. Asymptotic approximation will be made to the shoreline's brine concentration to evaluate the maximum salinity build-up in the coastal waters.

Overview of systems engineering approaches for a large-scale seawater desalination plant with a reverse osmosis network

Over 100 papers were reviewed to elucidate factors influencing large-scale seawater desalination plants with reverse osmosis networks (SWRO). This paper consists of subjects such as SWRO systems investigation, system models of pretreatment and RO networks, systems optimization to minimize the total cost of SWRO plant design, and the future direction of SWRO technology. In order to design a large-scale seawater desalination plant, a systematic understanding of SWRO processes should be followed. After investigating all the processes, including site-specific features, seawater intakes, pretreatment systems, RO networks, energy recovery systems, post-treatment systems, brine disposal, and the environmental impact of SWRO desalination, system models are discussed for predicting the performance of each system. Based on the minimal principle of total cost required for a full-scale SWRO plant, optimized results are discussed. Studies needed for developing future SWRO technologies are suggested.

Selecting Material for Large-Scale Seawater Desalination Facilities: Australia and U.S. Experiences

The need for additional water resources by many water utilities and a corresponding interest in brackish water and seawater desalination necessitates new materials and equipment to treat more corrosive waters, such as brackish water, raw seawater, reverse osmosis permeate, and membrane concentrate. This article focuses on seawater applications and highlights approaches taken by agencies in Australia and the United States to maximize long-term value of components of their large-scale seawater desalination facilities. This includes examining material selection and compatibility issues that develop during design, construction, and operation, as well as how these issues were mitigated. It is also important to evaluate the impact of specialized materials on equipment availability and maintenance and to help engineers and utilities understand key material compatibility and material supply issues associated with constructing a seawater desalination facility.

Technologies for large scale seawater desalination using concentrated solar radiation

This paper shows the principles and the present state of the art of concentrating solar power technology and explains the option for seawater desalination, either using electricity or steam generated in such plants. The economic potential of this technology in the MENA region can cope with the present and the expected future demand of electricity and water. First projects are now being realized, for electricity and also for combined heat and power for desalination, electricity and cooling.

Concentrating solar power for seawater desalination in the Middle East and North Africa

The paper presents a long-term scenario for the demand of freshwater in the Middle East and North Africa (MENA) and shows how it may be covered by a better use of the existing renewable water sources and by sea water desalination powered with solar energy. Growth of population and economy, increasing urbanization and industrialization, and the rather limited natural resources of potable water in MENA are leading to serious deficits of freshwater in many parts of MENA. Modern infrastructure for water distribution, enhanced efficiency of use and better water management are to be established as soon as possible. However, even the change to best practice would leave considerable deficits, which are poorly covered by over-exploiting groundwater resources. Increased use of desalted seawater is therefore unavoidable in order to maintain a reasonable level of water supply. The desalination of seawater based on fossil fuels is neither sustainable nor economically feasible in a long-term perspective, as fuels are increasingly becoming expensive and scarce. Concentrating solar power (CSP) offers a sustainable alternative to fossil fuels for large scale seawater desalination. CSP can help to solve the problem, but market introduction must start immediately in order to achieve the necessary freshwater production rates in time.

Integrating large scale seawater desalination plants within Israel’s water supply system

The paper lists and reviews the issues, considerations and factors that faced planners in Israel in introducing large scale seawater desalination plants within the national and regional water supply systems. Most importantly, the paper quantifies the cost and benefit consequences of these factors, thereby establishing their relative weight, importance and significance. Cost consequences relate not only to the effect each factor had on desalinated water costs at their inlets to the national or regional water supply grids, but also to its effect on overall investments and operating costs related to expanding the entire water supply system to meet projected increases in demand, including seasonal, multi-seasonal and local storage capacities, distribution line sizes, pumping energy requirements, etc., and to dealing with deteriorating groundwater quality, including rehabilitation of salinized and/or contaminated wells, etc. Benefits included factors such as potable water supply reliability and quality enhancement, expanded and environmentally safer water reuse potential, etc. As will be shown, the challenge was to create a master plan which accounts for all these factors and optimizes their overall cost-benefit ratio both short and long term.

Desalination – water for the next generation

Even though the volume of the earth's water is vast, less than 10 million of the 1,400 million cubic metres of water on the planet is of low salinity and suitable for use after applying conventional water treatment alone. The other 97.5% of the water on our planet is to be found in the oceans, where it is officially classified as seawater. Desalination provides a means of tapping this resource, and over the last 30 years, seawater desalination technology has made great strides in many arid regions of the world, such as the Middle East and the Mediterranean, and is starting to be considered viable even in cooler regions of the world not traditionally associated with water shortage (the UK for example.) • Filtration + Separation looks at the subject of desalination, starting with an overview of the current situation; we ask some experts in the field to point out the reasons why desalination has now become such an acceptable worldwide water treatment phenomenon (Factors behind the growth in desalination - below, and pages 15 – 18.) • On page 19, we briefly examine the different technical aspects of desalination available today (Desalination – the basics.) • We then publish two case studies; the first looks at Israel, which has embarked upon a large-scale seawater desalination program, most notably the Ashkelon project – a 100 million m3/year SWRO desalination plant (Case study: assessing the need for, and costs of, seawater desalination in Israel - pages 20 and 21.) • The second looks at Pretreatment - a vital part of any desalination process – using the US, California, Carlsbad seawater desalination pilot plant as an example (Case study: Pretreatment at Carlsbad seawater desalination pilot plant – pages 22 – 25.)

Water transfer versus desalination in North Africa: sustainability and cost comparison

AbstractThe North African region is experiencing water scarcity that is getting more severe with time. The regional annual average per capita water availability has been reduced from 2285 cubic meters in 1955 to 958 cubic meters in 1990 and is expected to reach 602 cubic meters by the year 2025. To meet the present and future water demands of the region the available options are limited to either long distance water transfers from the southern aquifers to the coastal areas or to investing in large scale seawater desalination technology. Economic analysis revealed that the cost of long distance water transfer can escalate to more than 0.83 US Dollars per cubic meter. When sustainability considerations are taken into account this figure may reach up to 2.35 US Dollars per cubic meter. While these figures were competitive with the cost of seawater desalination twenty years ago, the situation has been recently shifted in favor of seawater desalination which dropped from 5.5 US Dollars in 1979 to less than 0.55 US Dollars in 1999. It is concluded that sustainable development of North Africa will depend in the future on large scale desalination as a last resort. Presently, planned water transfer projects should be substituted by this fast growing technology as the best option.

Design and economics of RO seawater desalination

Large-scale seawater desalination is an attractive and viable alternative for the production of potable water in the absence of natural fresh water resources. Over the past two decades, the reverse osmosis (RO) process has allowed a tremendous reduction in the cost of potable water from seawater desalination. Indeed, cost studies conducted by various researchers have indicated that it is possible to obtain product water cost of about US$ 0.80/ m 3. This paper introduces a comprehensive, but tractable, means of modelling large-scale seawater RO desalination plants that can accommodate various flow configurations. The two most important considerations in RO plant modelling are the permeator performance characteristics and the permeator replacement scheme. In particular, the flux degradation of the permeator with operational age has to be accounted for. The RO model introduced here was used for extensive plant cost analysis. The cost studies indicate that the permeator cost makes up a large percentage (∼37%) of the total plant capital cost. This means that large-sized permeators, which offer smaller cost per unit membrane area, should be utilized in order to appreciate economies of scale. In terms of operating cost, the annual permeator replacement cost also forms the major portion. Interestingly, with the use of hydraulic energy recovery systems, the product water cost is relatively insensitive to energy price fluctuations. Also, cost comparisons conducted for a brine-stage RO plant configuration indicated that it is more costly than single-stage plants, especially for high concentration seawater.

Desalination in Australia operational experience and future prospects

To provide high quality fresh water to meet peak demands at times of drought in large population centres and to satisfy the requirements for water standards in industrial processes are perhaps the prime attractions of sea water desalination plants. Australia, the driest of earth's continents, will probably have a need for such water supply supplementation and industrial process application long before desalting is applied generally to agriculture or rural production. As the cost of fossil fuel gradually increases, it would also seem likely that the thermal energy required for desalting will come from nuclear fuels. In this paper the existing fresh water resources of the Australian continent are briefly surveyed. Present costs associated with supplying fresh water for industrial and domestic consumption to selected communities at representative locations of the Australian continent are assessed. The technology and economics of large scale sea water desalination plants operating on thermal cycles are discussed. In particular, the multi-stage flash evaporator principle is reviewed and its potential discussed. Consideration is given to the advantages and disadvantages of nuclear powered heat sources. Proposals are made for the control and conjunctive use of reservoirs and desalination plants. The optimisation of desalination plant size and its integration with reservoir storage schemes in two potential Australian locations is discussed.

Large long-tube vertical evaporators for sea water distillation

In this feasibility study of multiple-effect long tube vertical (MELTV) evaporators for large scale sea water desalination (more than 10 U.S.-mgd), an optimization of temperature profiles and performance ratio is carried out for both smooth and double-fluted tubes. The results are correlated in a generalized form in order to extend their usefulness. The calculations confirm the economic potential of MELTV evaporators and indicate that under some economic circumstances MELTV evaporators could show an advantage over multi-stage flash (MSF) evaporators. There is yet no sufficient operational experience with double-fluted tubes in MELTV evaporators but the present calculations confirm that their use has a potential for further reduction of cost of desalted water. Comparative data are given for the cost of water desalted in nuclear dual-purpose plants using MSF and MELTV evaporators.