Desalination

Desalination

Overview
Desalination, desalinization, or desalinisation refers to any of several processes that remove some amount of salt
Sodium chloride
Sodium chloride, also known as salt, common salt, table salt or halite, is an inorganic compound with the formula NaCl. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms...

 and other mineral
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...

s from saline water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

. More generally, desalination may also refer to the removal of salts and minerals, as in soil desalination.

Water is desalinated in order to convert salt water to fresh water so it is suitable for human consumption
Drinking water
Drinking water or potable water is water pure enough to be consumed or used with low risk of immediate or long term harm. In most developed countries, the water supplied to households, commerce and industry is all of drinking water standard, even though only a very small proportion is actually...

 or irrigation
Irrigation
Irrigation may be defined as the science of artificial application of water to the land or soil. It is used to assist in the growing of agricultural crops, maintenance of landscapes, and revegetation of disturbed soils in dry areas and during periods of inadequate rainfall...

. Sometimes the process produces table salt
Sodium chloride
Sodium chloride, also known as salt, common salt, table salt or halite, is an inorganic compound with the formula NaCl. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms...

 as a by-product
By-product
A by-product is a secondary product derived from a manufacturing process or chemical reaction. It is not the primary product or service being produced.A by-product can be useful and marketable or it can be considered waste....

.
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Encyclopedia
Desalination, desalinization, or desalinisation refers to any of several processes that remove some amount of salt
Sodium chloride
Sodium chloride, also known as salt, common salt, table salt or halite, is an inorganic compound with the formula NaCl. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms...

 and other mineral
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...

s from saline water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

. More generally, desalination may also refer to the removal of salts and minerals, as in soil desalination.

Water is desalinated in order to convert salt water to fresh water so it is suitable for human consumption
Drinking water
Drinking water or potable water is water pure enough to be consumed or used with low risk of immediate or long term harm. In most developed countries, the water supplied to households, commerce and industry is all of drinking water standard, even though only a very small proportion is actually...

 or irrigation
Irrigation
Irrigation may be defined as the science of artificial application of water to the land or soil. It is used to assist in the growing of agricultural crops, maintenance of landscapes, and revegetation of disturbed soils in dry areas and during periods of inadequate rainfall...

. Sometimes the process produces table salt
Sodium chloride
Sodium chloride, also known as salt, common salt, table salt or halite, is an inorganic compound with the formula NaCl. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms...

 as a by-product
By-product
A by-product is a secondary product derived from a manufacturing process or chemical reaction. It is not the primary product or service being produced.A by-product can be useful and marketable or it can be considered waste....

. Desalination is used on many seagoing ship
Ship
Since the end of the age of sail a ship has been any large buoyant marine vessel. Ships are generally distinguished from boats based on size and cargo or passenger capacity. Ships are used on lakes, seas, and rivers for a variety of activities, such as the transport of people or goods, fishing,...

s and submarine
Submarine
A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

s. Most of the modern interest in desalination is focused on developing cost-effective ways of providing fresh water for human use in regions where the availability of fresh water is, or is becoming, limited.

Large-scale desalination typically uses extremely large amounts of energy as well as specialized, expensive infrastructure, making it very costly compared to the use of fresh water from conventional sources such as rivers or groundwater
Groundwater
Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock...

.

However, along with recycled water this is one of the few non-rainfall dependent water sources particularly relevant to countries like Australia which traditionally have relied on rainfall in dams to provide their drinking water supplies.

The world's largest desalination plant is the Jebel Ali
Jebel Ali
Jebel Ali is a port town, located 35 kilometres southwest of the city of Dubai in the United Arab Emirates . The village has a thriving expatriate community with over 300 residents. The area is also home to "5,500 companies from 120 countries"....

 Desalination Plant (Phase 2) in the United Arab Emirates
United Arab Emirates
The United Arab Emirates, abbreviated as the UAE, or shortened to "the Emirates", is a state situated in the southeast of the Arabian Peninsula in Western Asia on the Persian Gulf, bordering Oman, and Saudi Arabia, and sharing sea borders with Iraq, Kuwait, Bahrain, Qatar, and Iran.The UAE is a...

. It is a dual-purpose facility that uses multi-stage flash distillation and is capable of producing 300 million cubic metres of water per year. By comparison the largest desalination plant in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 is located in Tampa Bay
Tampa Bay
Tampa Bay is a large natural harbor and estuary along the Gulf of Mexico on the west central coast of Florida, comprising Hillsborough Bay, Old Tampa Bay, Middle Tampa Bay, and Lower Tampa Bay."Tampa Bay" is not the name of any municipality...

, Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...

, and operated by Tampa Bay Water
Tampa Bay Water
Tampa Bay Water is a regional wholoesale drinking water utility that serves customers in the Tampa Bay, Florida region. The agency is a special district of the state created by interlocal agreement among six member governments...

, which began desalinating 34.7 million cubic meters of water per year in December 2007. The Tampa Bay plant runs at around 12% the output of the Jebel Ali Desalination Plants. The largest desalination plant in South Asia
South Asia
South Asia, also known as Southern Asia, is the southern region of the Asian continent, which comprises the sub-Himalayan countries and, for some authorities , also includes the adjoining countries to the west and the east...

 is the Minjur Desalination Plant near Chennai
Chennai
Chennai , formerly known as Madras or Madarasapatinam , is the capital city of the Indian state of Tamil Nadu, located on the Coromandel Coast off the Bay of Bengal. Chennai is the fourth most populous metropolitan area and the sixth most populous city in India...

 in India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

 which produces 100,000 cubic meters of water per day, or 36.5 million cubic meters of water per year. According to International Desalination Association 2009, there are 14,451 desalination plants in operation worldwide, producing 59.9 million cubic meters per day (15.8 billion gallons a day), a year on year increase of 12.3%.

Methods


The traditional process used in these operations is vacuum distillation
Vacuum distillation
Vacuum distillation is a method of distillation whereby the pressure above the liquid mixture to be distilled is reduced to less than its vapor pressure causing evaporation of the most volatile liquid...

—essentially the boiling of water at less than atmospheric pressure and thus a much lower temperature than normal. This is because the boiling of a liquid occurs when the vapor pressure
Vapor pressure
Vapor pressure or equilibrium vapor pressure is the pressure of a vapor in thermodynamic equilibrium with its condensed phases in a closed system. All liquids have a tendency to evaporate, and some solids can sublimate into a gaseous form...

 equals the ambient pressure and vapor pressure increases with temperature. Thus, because of the reduced temperature, energy is saved. A leading distillation method is multi-stage flash distillation accounting for 85% of production worldwide in 2004.

The principal competing processes use membranes to desalinate, principally applying reverse osmosis
Reverse osmosis
Reverse osmosis is a membrane technical filtration method that removes many types of large molecules and ions from solutions by applying pressure to the solution when it is on one side of a selective membrane. The result is that the solute is retained on the pressurized side of the membrane and...

 technology. Membrane processes use semi-permeable membranes and pressure to separate salts from water. Reverse osmosis plant
Reverse osmosis plant
A reverse osmosis plant is a manufacturing plant where the process of reverse osmosis takes place. An average modern reverse osmosis plant needs six kilowatt-hours of electricity to desalinate one cubic metre of water. The process also results in an amount of salty briny waste...

 membrane systems typically use less energy than thermal distillation, which has led to a reduction in overall desalination costs over the past decade. Desalination remains energy intensive, however, and future costs will continue to depend on the price of both energy and desalination technology.

Cogeneration


Cogeneration
Cogeneration
Cogeneration is the use of a heat engine or a power station to simultaneously generate both electricity and useful heat....

 is the process of using excess heat from power production to accomplish another task. For desalination, cogeneration is the production of potable water from seawater or brackish groundwater in an integrated, or "dual-purpose", facility in which a power plant is used as the source of energy for the desalination process. The facility’s energy production may be dedicated entirely to the production of potable water (a stand-alone facility), or excess energy may be produced and incorporated into the energy grid (a true cogeneration facility). There are various forms of cogeneration, and theoretically any form of energy production could be used. However, the majority of current and planned cogeneration desalination plants use either fossil fuels or nuclear power
Nuclear power
Nuclear power is the use of sustained nuclear fission to generate heat and electricity. Nuclear power plants provide about 6% of the world's energy and 13–14% of the world's electricity, with the U.S., France, and Japan together accounting for about 50% of nuclear generated electricity...

 as their source of energy. Most plants are located in the Middle East
Middle East
The Middle East is a region that encompasses Western Asia and Northern Africa. It is often used as a synonym for Near East, in opposition to Far East...

 or North Africa
North Africa
North Africa or Northern Africa is the northernmost region of the African continent, linked by the Sahara to Sub-Saharan Africa. Geopolitically, the United Nations definition of Northern Africa includes eight countries or territories; Algeria, Egypt, Libya, Morocco, South Sudan, Sudan, Tunisia, and...

, due to their petroleum resources and subsidies. The advantage of dual-purpose facilities is that they can be more efficient in energy consumption, thus making desalination a more viable option for drinking water in areas of scarce water resources.


In a December 26, 2007, opinion column in the The Atlanta Journal-Constitution
The Atlanta Journal-Constitution
The Atlanta Journal-Constitution is the only major daily newspaper in Atlanta, Georgia, United States, and its suburbs. The AJC, as it is called, is the flagship publication of Cox Enterprises. The Atlanta Journal-Constitution is the result of the merger between The Atlanta Journal and The Atlanta...

, Nolan Hertel, a professor of nuclear and radiological engineering at Georgia Tech
Georgia Institute of Technology
The Georgia Institute of Technology is a public research university in Atlanta, Georgia, in the United States...

, wrote, "... nuclear reactors can be used ... to produce large amounts of potable water. The process is already in use in a number of places around the world, from India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

 to Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

 and Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

. Eight nuclear reactors coupled to desalination plants are operating in Japan alone ... nuclear desalination plants could be a source of large amounts of potable water transported by pipelines hundreds of miles inland..."

Additionally, the current trend in dual-purpose facilities is hybrid configurations, in which the permeate from an RO desalination component is mixed with distillate from thermal desalination. Basically, two or more desalination processes are combined along with power production. Such facilities have already been implemented in Saudi Arabia
Saudi Arabia
The Kingdom of Saudi Arabia , commonly known in British English as Saudi Arabia and in Arabic as as-Sa‘ūdiyyah , is the largest state in Western Asia by land area, constituting the bulk of the Arabian Peninsula, and the second-largest in the Arab World...

 at Jeddah
Jeddah
Jeddah, Jiddah, Jidda, or Jedda is a city located on the coast of the Red Sea and is the major urban center of western Saudi Arabia. It is the largest city in Makkah Province, the largest sea port on the Red Sea, and the second largest city in Saudi Arabia after the capital city, Riyadh. The...

 and Yanbu.

A typical aircraft carrier
Aircraft carrier
An aircraft carrier is a warship designed with a primary mission of deploying and recovering aircraft, acting as a seagoing airbase. Aircraft carriers thus allow a naval force to project air power worldwide without having to depend on local bases for staging aircraft operations...

 in the U.S. military uses nuclear power to desalinate 400000 gallons (1,514,164.8 l) of water per day.

Economics


A number of factors determine the capital and operating costs for desalination: capacity and type of facility, location, feed water, labor, energy, financing, and concentrate disposal. Desalination stills now control pressure, temperature and brine concentrations to optimize the water extraction efficiency. Nuclear-powered
Nuclear power
Nuclear power is the use of sustained nuclear fission to generate heat and electricity. Nuclear power plants provide about 6% of the world's energy and 13–14% of the world's electricity, with the U.S., France, and Japan together accounting for about 50% of nuclear generated electricity...

 desalination might be economical on a large scale.

While noting that costs are falling, and generally positive about the technology for affluent areas that are proximate to oceans, one study argues that "Desalinated water may be a solution for some water-stress regions, but not for places that are poor, deep in the interior of a continent, or at high elevation. Unfortunately, that includes some of the places with biggest water problems." and "Indeed, one needs to lift the water by 2000 metres (6,561.7 ft), or transport it over more than 1600 kilometres (994.2 mi) to get transport costs equal to the desalination costs. Thus, it may be more economical to transport fresh water from somewhere else than to desalinate it. In places far from the sea, like New Delhi
New Delhi
New Delhi is the capital city of India. It serves as the centre of the Government of India and the Government of the National Capital Territory of Delhi. New Delhi is situated within the metropolis of Delhi. It is one of the nine districts of Delhi Union Territory. The total area of the city is...

, or in high places, like Mexico City
Mexico City
Mexico City is the Federal District , capital of Mexico and seat of the federal powers of the Mexican Union. It is a federal entity within Mexico which is not part of any one of the 31 Mexican states but belongs to the federation as a whole...

, high transport costs would add to the high desalination costs. Desalinated water is also expensive in places that are both somewhat far from the sea and somewhat high, such as Riyadh
Riyadh
Riyadh is the capital and largest city of Saudi Arabia. It is also the capital of Riyadh Province, and belongs to the historical regions of Najd and Al-Yamama. It is situated in the center of the Arabian Peninsula on a large plateau, and is home to 5,254,560 people, and the urban center of a...

 and Harare
Harare
Harare before 1982 known as Salisbury) is the largest city and capital of Zimbabwe. It has an estimated population of 1,600,000, with 2,800,000 in its metropolitan area . Administratively, Harare is an independent city equivalent to a province. It is Zimbabwe's largest city and its...

. In many places, the dominant cost is desalination, not transport; the process would therefore be relatively less expensive in places like Beijing
Beijing
Beijing , also known as Peking , is the capital of the People's Republic of China and one of the most populous cities in the world, with a population of 19,612,368 as of 2010. The city is the country's political, cultural, and educational center, and home to the headquarters for most of China's...

, Bangkok
Bangkok
Bangkok is the capital and largest urban area city in Thailand. It is known in Thai as Krung Thep Maha Nakhon or simply Krung Thep , meaning "city of angels." The full name of Bangkok is Krung Thep Mahanakhon Amon Rattanakosin Mahintharayutthaya Mahadilok Phop Noppharat Ratchathani Burirom...

, Zaragoza
Zaragoza
Zaragoza , also called Saragossa in English, is the capital city of the Zaragoza Province and of the autonomous community of Aragon, Spain...

, Phoenix
Phoenix, Arizona
Phoenix is the capital, and largest city, of the U.S. state of Arizona, as well as the sixth most populated city in the United States. Phoenix is home to 1,445,632 people according to the official 2010 U.S. Census Bureau data...

, and, of course, coastal cities like Tripoli
Tripoli
Tripoli is the capital and largest city in Libya. It is also known as Western Tripoli , to distinguish it from Tripoli, Lebanon. It is affectionately called The Mermaid of the Mediterranean , describing its turquoise waters and its whitewashed buildings. Tripoli is a Greek name that means "Three...

." After being desalinated at Jubail
Jubail
Jubail , is a city in the Eastern province on the Persian Gulf coast of Saudi Arabia. It consists of the Old Town of Al Jubail, which was originally a small fishing village, up to 1975 and the new industrial area....

, Saudi Arabia
Saudi Arabia
The Kingdom of Saudi Arabia , commonly known in British English as Saudi Arabia and in Arabic as as-Sa‘ūdiyyah , is the largest state in Western Asia by land area, constituting the bulk of the Arabian Peninsula, and the second-largest in the Arab World...

, water is pumped 200 miles (321.9 km) inland through a pipeline to the capital city of Riyadh
Riyadh
Riyadh is the capital and largest city of Saudi Arabia. It is also the capital of Riyadh Province, and belongs to the historical regions of Najd and Al-Yamama. It is situated in the center of the Arabian Peninsula on a large plateau, and is home to 5,254,560 people, and the urban center of a...

. For cities on the coast, desalination is being increasingly viewed as an untapped and unlimited water source.

Desalination makes sense only after less expensive options are exhausted, including recycling water and fixing broken infrastructure. Water is reused in Las Vegas NV, Fountain Valley CA, Fairfax VA, El Paso TX and Scottsdale AZ. Compared to desalinated sea water, recycling requires 50% less energy due to the significantly lower salt content and produces new water at 30% less cost to the consumer, without the damage to marine life and ecosystems common to desalination plants.

Israel is now desalinating water at a cost of US$0.53 per cubic meter. Singapore is desalinating water for US$0.49 per cubic meter. Many large coastal cities in developed countries are considering the feasibility of seawater desalination, due to its cost effectiveness compared with other water supply options, which can include mandatory installation of rainwater tanks or stormwater harvesting infrastructure. Studies have shown that the desalination option is more cost-effective than large-scale recycled water for drinking, and more cost-effective in Sydney than the vastly expensive option of mandatory installation of rainwater tanks or stormwater harvesting infrastructure. The city of Perth
Perth, Western Australia
Perth is the capital and largest city of the Australian state of Western Australia and the fourth most populous city in Australia. The Perth metropolitan area has an estimated population of almost 1,700,000....

 has been successfully operating a reverse osmosis seawater desalination plant since 2006, and the Western Australian government have announced that a second plant will be built to serve the city's needs. A desalination plant is now operating in Australia's largest city of Sydney
Sydney
Sydney is the most populous city in Australia and the state capital of New South Wales. Sydney is located on Australia's south-east coast of the Tasman Sea. As of June 2010, the greater metropolitan area had an approximate population of 4.6 million people...

, and the Wonthaggi desalination plant under construction in Wonthaggi, Victoria
Wonthaggi, Victoria
Wonthaggi is a town located south east of Melbourne via the South Gippsland and Bass Highways, in the Bass Coast Shire of Gippsland, Victoria, Australia...

.

The Perth desalination plant is powered partially by renewable energy from the Emu Downs Wind Farm. A wind farm at Bungendore in NSW has been purpose-built to generate enough renewable energy
Renewable energy
Renewable energy is energy which comes from natural resources such as sunlight, wind, rain, tides, and geothermal heat, which are renewable . About 16% of global final energy consumption comes from renewables, with 10% coming from traditional biomass, which is mainly used for heating, and 3.4% from...

 to offset the energy use of the Sydney plant, mitigating concerns about harmful greenhouse gas emissions, a common argument used against seawater desalination due to the energy requirements of the technology. The purchase or production of renewable energy to power desalination plants naturally adds to the capital and/or operating costs of desalination. However, recent experience in Perth and Sydney indicates that the additional cost is acceptable to communities, as a city may then augment its water supply without doing environmental harm to the atmosphere.
The Queensland state government also purchased renewable energy certificates on behalf of its Gold Coast plant which will see the plant offset its carbon emissions for the initial 18 to 20 months of operations, bringing its environmental footprint down, in line with the other major plants that will be operating around the same time, in Perth and Sydney.

In December 2007, the South Australian government announced that it would build a seawater desalination plant for the city of Adelaide, Australia, located at Port Stanvac
Lonsdale, South Australia
Lonsdale is an industrial suburb located south of Adelaide, South Australia, within the City of Onkaparinga.Lonsdale was farmed from shortly after European settlement until the 1950s, when the South Australian Housing Trust acquired much of the land for industrial use...

. The desalination plant is to be funded by raising water rates to achieve full cost recovery. An online, unscientific poll showed that nearly 60% of votes cast were in favor of raising water rates to pay for desalination.

A January 17, 2008, article in the Wall Street Journal states, "In November, Connecticut-based Poseidon Resources Corp. won a key regulatory approval to build the US$300 million water-desalination plant
Carlsbad desalination plant
Carlsbad desalination plant is a desalination plant under construction in Carlsbad, California. It is scheduled to be the largest desalination plant in the United States...

 in Carlsbad
Carlsbad, California
-2010:The 2010 United States Census reported that Carlsbad had a population of 105,328. The population density was 2,693.1 people per square mile . The racial makeup of Carlsbad was 87,205 White, 1,379 African American, 514 Native American, 7,460 Asian, 198 Pacific Islander, 4,189 from other...

, north of San Diego. The facility would produce 50000000 gallons (189,270,600 l) of drinking water per day, enough to supply about 100,000 homes ... Improved technology has cut the cost of desalination in half in the past decade, making it more competitive ... Poseidon plans to sell the water for about US $950 per acre-foot [1200 cubic metres (42,377.6 cu ft)]. That compares with an average US$700 an acre-foot [1200 m³] that local agencies now pay for water."
$1,000 per acre-foot works out to $3.06 for 1,000 gallons, or $.81 for 1 cubic meter, which is the unit of water measurement that residential water users are accustomed to being billed in.

While this regulatory hurdle was met, Poseidon Resources is not able to break ground until the final approval of a mitigation project for the damage done to marine life through the intake pipe, as is required by California law. Poseidon Resources has made progress in Carlsbad, CA, despite its unsuccessful attempt to complete construction of Tampa Bay Desal, a desalination plant in Tampa Bay, FL, in 2001. The Board of Directors of Tampa Bay Water
Tampa Bay Water
Tampa Bay Water is a regional wholoesale drinking water utility that serves customers in the Tampa Bay, Florida region. The agency is a special district of the state created by interlocal agreement among six member governments...

 were forced to buy Tampa Bay Desal from Poseidon Resources in 2001 to prevent a third failure of the project. Tampa Bay Water
Tampa Bay Water
Tampa Bay Water is a regional wholoesale drinking water utility that serves customers in the Tampa Bay, Florida region. The agency is a special district of the state created by interlocal agreement among six member governments...

 faced five years of engineering problems and operation at 20% capacity due to marine life and growth captured and stuck to reverse osmosis filters prior to fully utilizing this facility in 2007.

According to a May 9, 2008, article in Forbes
Forbes
Forbes is an American publishing and media company. Its flagship publication, the Forbes magazine, is published biweekly. Its primary competitors in the national business magazine category are Fortune, which is also published biweekly, and Business Week...

, a San Leandro, California
San Leandro, California
San Leandro is a city in Alameda County, California, United States. It is considered a suburb of Oakland and San Francisco. The population was 84,950 as of 2010 census. The climate of the city is mild throughout the year.-Geography and water resources:...

, company called Energy Recovery Inc.
Energy Recovery Inc.
Energy Recovery Inc. is a California multinational corporation which designs and manufactures energy recovery products and technology for seawater reverse osmosis desalination...

 has been desalinating water for US $0.46 per cubic meter.

According to a June 5, 2008, article in the Globe and Mail, a Jordanian-born chemical engineering doctoral student at the University of Ottawa
University of Ottawa
The University of Ottawa is a bilingual, research-intensive, non-denominational, international university in Ottawa, Ontario. It is one of the oldest universities in Canada. It was originally established as the College of Bytown in 1848 by the Missionary Oblates of Mary Immaculate...

, named Mohammed Rasool Qtaisha, has invented a new desalination technology that is alleged to be between 600% and 700% more water output per square meter of membrane than current technology. According to the article, General Electric
General Electric
General Electric Company , or GE, is an American multinational conglomerate corporation incorporated in Schenectady, New York and headquartered in Fairfield, Connecticut, United States...

 is looking into similar technology, and the U.S. National Science Foundation
National Science Foundation
The National Science Foundation is a United States government agency that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National Institutes of Health...

 announced a grant to the University of Michigan
University of Michigan
The University of Michigan is a public research university located in Ann Arbor, Michigan in the United States. It is the state's oldest university and the flagship campus of the University of Michigan...

 to study it as well. Because the patents were still being worked out, the article was very vague about the details of this alleged technology.

While desalinating 1000 gallons (3,785.4 l) of water can cost as much as $3, the same amount of bottled water
Bottled water
Bottled water is drinking water packaged in plastic or glass water bottles. Bottled water may be carbonated or not...

 costs $7,945.

Intake


One of the main environmental considerations of ocean water desalination plants is the impact of the open ocean water intakes, especially when co-located with power plants. Many proposed ocean desalination plants' initial plans relied on these intakes despite perpetuating ongoing impacts on marine life. In the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, due to a recent court ruling under the Clean Water Act
Clean Water Act
The Clean Water Act is the primary federal law in the United States governing water pollution. Commonly abbreviated as the CWA, the act established the goals of eliminating releases of high amounts of toxic substances into water, eliminating additional water pollution by 1985, and ensuring that...

, these intakes are no longer viable without reducing mortality, by 90%, of the life in the ocean; the plankton
Plankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...

, fish eggs and fish larvae. There are alternatives, including beach wells that eliminate this concern, but require more energy and higher costs while limiting output. Other environmental concerns include air pollution
Air pollution
Air pollution is the introduction of chemicals, particulate matter, or biological materials that cause harm or discomfort to humans or other living organisms, or cause damage to the natural environment or built environment, into the atmosphere....

 and greenhouse gas
Greenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...

 emissions from the power plants.

Outflow


To limit the environmental impact of returning the brine to the ocean, it can be diluted with another stream of water entering the ocean, such as the outfall of a waste water treatment plant
Sewage treatment
Sewage treatment, or domestic wastewater treatment, is the process of removing contaminants from wastewater and household sewage, both runoff and domestic. It includes physical, chemical, and biological processes to remove physical, chemical and biological contaminants...

 or power plant. While seawater power plant cooling water outfalls are not freshwater like waste water treatment plant outfalls, the salinity of the brine will still be reduced. If the power plant is medium- to large-sized and the desalination plant is not enormous, the flow of the power plant's cooling water is likely to be at least several times larger than that of the desalination plant. Another method to reduce the increase in salinity is to spread the brine via a diffuser to mix in a mixing zone so that there is only a slight increase in salinity. For example, once the pipeline containing the brine reaches the sea floor, it can split off into many branches, each one releasing the brine gradually along its length through small holes. This method can be used in combination with the joining of the brine with power plant or waste water plant outfalls.

There are methods of desalination, particularly in combination with open pond evaporation (solar desalination
Solar Desalination
Solar desalination is a technique to desalinate water using solar energy. Solar desalination in the modern era extends back to the early 1950s when simple solar stills were studied for remote desert and coastal communities...

), that do not discharge brine back into the ocean at all.

The concentrated seawater has the potential to harm ecosystem
Ecosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....

s, especially marine environments in regions with low turbidity
Turbidity
Turbidity is the cloudiness or haziness of a fluid caused by individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of water quality....

 and high evaporation that already have elevated salinity. Examples of such locations are the Persian Gulf
Persian Gulf
The Persian Gulf, in Southwest Asia, is an extension of the Indian Ocean located between Iran and the Arabian Peninsula.The Persian Gulf was the focus of the 1980–1988 Iran-Iraq War, in which each side attacked the other's oil tankers...

, the Red Sea
Red Sea
The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez...

 and, in particular, coral
Coral
Corals are marine animals in class Anthozoa of phylum Cnidaria typically living in compact colonies of many identical individual "polyps". The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.A coral "head" is a colony of...

 lagoon
Lagoon
A lagoon is a body of shallow sea water or brackish water separated from the sea by some form of barrier. The EU's habitat directive defines lagoons as "expanses of shallow coastal salt water, of varying salinity or water volume, wholly or partially separated from the sea by sand banks or shingle,...

s of atoll
Atoll
An atoll is a coral island that encircles a lagoon partially or completely.- Usage :The word atoll comes from the Dhivehi word atholhu OED...

s and other tropical
Tropics
The tropics is a region of the Earth surrounding the Equator. It is limited in latitude by the Tropic of Cancer in the northern hemisphere at approximately  N and the Tropic of Capricorn in the southern hemisphere at  S; these latitudes correspond to the axial tilt of the Earth...

 islands around the world.

The UAE, Qatar, Bahrain, Saudi Arabia, Kuwait and Iran have 120 desalination plants between them. These plants flush nearly 24 tons of chlorine, 65 tons of algae-harming antiscalants used to descale pipes, and around 300 kg of copper into the Persian Gulf every day.
Because the brine is denser than the surrounding sea water due to the higher solute concentration, discharge into water bodies means that the ecosystems on the bed of the water body are most at risk because the brine sinks and remains there long enough to damage the ecosystems. Careful re-introduction can minimize this problem. For example, for the desalination plant and ocean outlet structures to be built in Sydney from late 2007, the water authority states that the ocean outlets will be placed in locations at the seabed that will maximize the dispersal of the concentrated seawater, such that it will be indistinguishable from normal seawater between 50 and 75 m (164 and 246.1 ) from the outlet points. Sydney is fortunate to have typical oceanographic conditions off the coast that allow for such rapid dilution of the concentrated byproduct, thereby minimizing harm to the environment.

In Perth, Australia, in 2007, the Kwinana Desalination Plant
Kwinana Desalination Plant
The Kwinana Desalination Plant, located south of Perth, Western Australia, turns seawater from Cockburn Sound into nearly 140 megalitres of drinking water per day, supplying the Perth metropolitan area....

 was opened. The water is sucked in from the ocean at only 0.1 m/s, which is slow enough to let fish escape. The plant provides nearly 140000 cubic metres (4,944,053.3 cu ft) of clean water per day. This is the same at Queensland's Gold Coast Desalination Plant and Sydney's Desalination Plant.

Desalination compared to other water supply options


Increased water conservation
Water conservation
Water conservation refers to reducing the usage of water and recycling of waste water for different purposes such as cleaning, manufacturing, and agricultural irrigation.- Water conservation :Water conservation can be defined as:...

 and water use efficiency remain the most cost-effective priorities in areas of the world where there is a large potential to improve the efficiency of water use practices. While comparing ocean water desalination to waste water reclamation for drinking water shows desalination as the first option, using reclamation for irrigation and industrial use provides multiple benefits. Urban runoff and storm water capture also provide benefits in treating, restoring and recharging groundwater.
A proposed alternative to desalinization in the state of California and other areas in the American Southwest is the commercial importation of bulk water either by very large crude carriers
Oil tanker
An oil tanker, also known as a petroleum tanker, is a merchant ship designed for the bulk transport of oil. There are two basic types of oil tankers: the crude tanker and the product tanker. Crude tankers move large quantities of unrefined crude oil from its point of extraction to refineries...

 converted to water carriers, or via pipelines. The idea is politically unpopular in Canada, where governments have been scrambling to impose trade barriers to bulk water exports as a result of a claim filed in 1999 under Chapter 11 of the North American Free Trade Agreement
North American Free Trade Agreement
The North American Free Trade Agreement or NAFTA is an agreement signed by the governments of Canada, Mexico, and the United States, creating a trilateral trade bloc in North America. The agreement came into force on January 1, 1994. It superseded the Canada – United States Free Trade Agreement...

 (NAFTA) by Sun Belt Water Inc. a company established in 1990 in Santa Barbara, California, to address pressing local needs due to a severe drought in that area. Sun Belt maintains a web site where documents relating to their dispute are posted online.

Experimental techniques and other developments


In the past, many novel desalination techniques have been researched with varying degrees of success.

One such process which has recently been commercialised by Modern Water plc is a forward osmosis
Forward osmosis
Forward osmosis is an osmotic process that, like reverse osmosis, uses a semi-permeable membrane to effect separation of water from dissolved solutes...

 based process for desalinated water, with a number of plants reported in operation.

Other techniques have also attracted research funding. For example, to offset the energy requirements of desalination, the U.S. government is working to develop practical solar desalination
Solar Desalination
Solar desalination is a technique to desalinate water using solar energy. Solar desalination in the modern era extends back to the early 1950s when simple solar stills were studied for remote desert and coastal communities...

.

As an example of newer theoretical approaches for desalination, focusing specifically on maximizing energy efficiency and cost effectiveness, the Passarell Process may be considered.

Other approaches involve the use of geothermal energy. From an environmental and economic point of view, in most locations geothermal desalination
Geothermal desalination
Geothermal desalination is a process under development for the production of fresh water using heat energy. Claimed benefits of this method of desalination are that it requires less maintenance than reverse osmosis membranes and that the primary energy input is from geothermal heat, which is a...

 can be preferable to using fossil groundwater or surface water for human needs, as in many regions the available surface and groundwater resources already have long been under severe stress.

Recent research in the U.S. indicates that nanotube membrane
Nanotube membrane
Nanotube membrane is either a single, open-ended nanotube or a film composed of open-ended nanotubes that are oriented perpendicularly to the surface of an impermeable film matrix like the cells of a honeycomb. 'Impermeable' is essential here to distinguish nanotube membrane with traditional, well...

s may prove to be extremely effective for water filtration and may produce a viable water desalination process that would require substantially less energy than reverse osmosis.

Another method being looked into for water desalination is the use of biomimetic membrane
Biological membrane
A biological membrane or biomembrane is an enclosing or separatingmembrane that acts as a selective barrier, within or around a cell. It consists of a lipid bilayer with embedded proteins that may constitute close to 50% of membrane content...

s

On June 23, 2008, it was reported that Siemens Water Technologies had developed a new technology, based on applying electric field on seawater, that desalinates one cubic meter of water while using only 1.5 kWh of energy, which, according to the report, is one half the energy that other processes use.

Fresh water can also be produced by freezing seawater, as happens naturally in the polar regions, and is known as freeze-thaw desalination.

According to MSNBC
MSNBC
MSNBC is a cable news channel based in the United States available in the US, Germany , South Africa, the Middle East and Canada...

, a report by Lux Research estimated that the worldwide desalinated water supply will triple between 2008 and 2020.

Desalination through evaporation and condensation for crops growth


The Seawater Greenhouse
Seawater Greenhouse
The Seawater Greenhouse is a technology that enables the growth of crops in arid regions, using a greenhouse structure, seawater and solar energy...

 uses evaporation and condensation natural processes inside a greenhouse powered by solar energy to enable the growth of crops in coastal arid land.

Low-temperature thermal desalination


Low-temperature thermal desalination
Low-temperature thermal desalination
Low-temperature thermal desalination is a desalination technique takes advantage of the fact that water boils at low pressures, even as low as ambient temperature. The system uses vacuum pumps to create a low pressure, low-temperature environment in which water boils at a temperature gradient of 8...

 (LTTD) takes advantage of the fact that water boils at low pressures, even as low as ambient temperature. The system uses vacuum pumps to create a low pressure, low-temperature environment in which water boils at a temperature gradient of 8 to 10 °C between two volumes of water. Cooling water is supplied from sea depths of as much as 600 metres (1,968.5 ft). This cold water is pumped through coils to condense the evaporated water vapor. The resulting condensate is purified water. The LTTD process may also take advantage of the temperature gradient available at power plants, where large quantities of warm waste water are discharged from the plant, reducing the energy input needed to create a temperature gradient.

The principle of LTTD is known for a long time, originally stemming from ocean thermal energy conversion
Ocean thermal energy conversion
Ocean Thermal Energy Conversion uses the difference between cooler deep and warmer shallow or surface ocean waters to run a heat engine and produce useful work, usually in the form of electricity....

 research. Some experiments were conducted in U.S. and Japan to test the low-temperature driven desalination technology. In Japan, a spray flash evaporation system was tested by Saga University. In US, at Hawaii Islands, the National Energy Laboratory tested an open-cycle OTEC plant with fresh water and power production using a temperature of 20 °C between surface water and water at a depth of around 500 m. LTTD was studied by India's National Institute of Ocean Technology (NIOT) from 2004. Their first LTTD plant was opened in 2005 at Kavaratti in the Lakshadweep
Lakshadweep
Lakshadweep , formerly known as the Laccadive, Minicoy, and Amindivi Islands, is a group of islands in the Laccadive Sea, 200 to 440 km off the coast of the South West Indian state of Kerala...

 islands. The plant's capacity is 100000 litres (211,337.9 US pt)/day, at a capital cost of INR 50 million (€922,000). The plant uses deep water at a temperature of 7 to 15 °C (44.6 to 59 F). In 2007, NIOT opened an experimental floating LTTD plant off the coast of Chennai
Chennai
Chennai , formerly known as Madras or Madarasapatinam , is the capital city of the Indian state of Tamil Nadu, located on the Coromandel Coast off the Bay of Bengal. Chennai is the fourth most populous metropolitan area and the sixth most populous city in India...

 with a capacity of 1000000 litres (2,113,378.5 US pt)/day. A smaller plant was established in 2009 at the North Chennai Thermal Power Station to prove the LTTD application where power plant cooling water is available.

Thermo-ionic process


In October 2009, Saltworks Technologies, a Canadian firm, announced a process that uses solar or other thermal heat to drive an ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...

ic current that empties all the sodium and chlorine ions from the water.

Aruba


The island of Aruba has a large (world’s largest at the time of its inauguration) desalination plant with the total installed capacity of 42,000 metric tons (11.1 million gallons or 42 × 103 m3) per day.

Australia


A combination of increased water usage and lower rainfall/drought in Australia has caused State governments to build a number of desalination plants, including the recently commissioned Kurnell Desalination Plant
Kurnell Desalination Plant
The Sydney Desalination Plant is a drinking water supply project operated by Veolia Water Australia Pty Ltd on behalf of Sydney Water, Sydney's State-owned water supply corporation. It is located in the Kurnell industrial estate area, in Sydney's southern suburbs. The desalination plant itself was...

 serving the Sydney
Sydney
Sydney is the most populous city in Australia and the state capital of New South Wales. Sydney is located on Australia's south-east coast of the Tasman Sea. As of June 2010, the greater metropolitan area had an approximate population of 4.6 million people...

 area. While desalination has been adopted by state governments to secure water supply, it is highly energy intensive (~$140 energy demand/ML) and has a high carbon footprint due to continued reliance on Australia's coal-based energy generation.

A Seawater Greenhouse
Seawater Greenhouse
The Seawater Greenhouse is a technology that enables the growth of crops in arid regions, using a greenhouse structure, seawater and solar energy...

 has been built in Port Augusta in 2010

Bahrain

  • The Al Hidd Desalination Plant on Muharraq
    Muharraq
    Muharraq , is Bahrain's third largest city, and served as its capital until 1923. The city is located on Muharraq Island and has long been a centre of religiosity...

     island treats seawater through a multistage flash process, and produces 30 million USgals (113,562.4 m³) per day. This project was completed in 2000. The Al Hidd distillate forwarding station, comprises a 410 million litres distillate water storage in 45 million litres steel tanks. A 135 million litres/day forwarding pumping station sends flows to the Hidd blending station, Muharraq blending station, Hoora blending station, Sanabis blending station and Seef blending station and which has an option for gravity supply for low flows to blending pumps and pumps which forward to Janusan, Budiya and Saar.
  • When completed in three phases, the Durrat Al Bahrain
    Durrat Al Bahrain
    Durrat Al Bahrain is the largest artificial island in Bahrain after the Amwaj Islands. The US$6 billion project will consist of a series of 13 large artificial islands, covering an area of over...

     sea water reverse osmosis (SWRO) desalination plant will have a capacity of 36,000 cubic meters of potable water per day which will serve the irrigation needs of the entire Durrat Al Bahrain development. The Bahrain-based utility company, Energy Central Co (ECC) will provide the plant a 25-year design, build and operate contract.

China


China operates the Beijiang Desalination Plant in Tianjin
Tianjin
' is a metropolis in northern China and one of the five national central cities of the People's Republic of China. It is governed as a direct-controlled municipality, one of four such designations, and is, thus, under direct administration of the central government...

, a combination desalination and coal-fired power plant designed to alleviate Tianjin's critical water shortage. Though the facility has the capacity to produce 200,000 cubic meters of potable water per day, it has never operated at more than one quarter capacity due to difficulties with local utility companies and an inadequate local infrastructure.

Cyprus


There are also desalination plants in Cyprus
Cyprus
Cyprus , officially the Republic of Cyprus , is a Eurasian island country, member of the European Union, in the Eastern Mediterranean, east of Greece, south of Turkey, west of Syria and north of Egypt. It is the third largest island in the Mediterranean Sea.The earliest known human activity on the...

, like the one near the town of Larnaca
Larnaca
Larnaca, is the third largest city on the southern coast of Cyprus after Nicosia and Limassol. It has a population of 72,000 and is the island's second largest commercial port and an important tourist resort...

. This is called the Dhekelia Desalination Plant, which utilises the reverse osmosis system.

Gibraltar


The fresh water supply in Gibraltar
Gibraltar
Gibraltar is a British overseas territory located on the southern end of the Iberian Peninsula at the entrance of the Mediterranean. A peninsula with an area of , it has a northern border with Andalusia, Spain. The Rock of Gibraltar is the major landmark of the region...

 is supplied by a number of reverse osmosis
Reverse osmosis
Reverse osmosis is a membrane technical filtration method that removes many types of large molecules and ions from solutions by applying pressure to the solution when it is on one side of a selective membrane. The result is that the solute is retained on the pressurized side of the membrane and...

 and multi-stage flash desalination plants. There is also a demonstration forward osmosis
Forward osmosis
Forward osmosis is an osmotic process that, like reverse osmosis, uses a semi-permeable membrane to effect separation of water from dissolved solutes...

 desalination plant operational.

Israel


The Hadera seawater reverse osmosis
Reverse osmosis
Reverse osmosis is a membrane technical filtration method that removes many types of large molecules and ions from solutions by applying pressure to the solution when it is on one side of a selective membrane. The result is that the solute is retained on the pressurized side of the membrane and...

 (SWRO) desalination plant in Israel
Science and technology in Israel
Science and technology in Israel is one of the country's most developed sectors. The percentage of Israelis engaged in scientific and technological inquiry, and the amount spent on research and development in relation to gross domestic product , is amongst the highest in the world...

 is the largest of its kind in the world. The project was developed as a Build-Operate-Transfer
Build-Operate-Transfer
Build-own-operate-transfer or build-operate-transfer is a form of project financing, wherein a private entity receives a concession from the private or public sector to finance, design, construct, and operate a facility stated in the concession contract...

 (BOT) by a consortium of three international companies: Veolia water, IDE Technologies and Elran.
|+ Existing Israeli water desalination facilities
|-
! Location!! Opened !! Capacity
(mln m3/year) !! Cost of water
(per m3) !! Notes
|->
Ashkelon
Ashkelon
Ashkelon is a coastal city in the South District of Israel on the Mediterranean coast, south of Tel Aviv, and north of the border with the Gaza Strip. The ancient seaport of Ashkelon dates back to the Neolithic Age...

 
August 2005 120 (as of 2010) NIS 2.60 >- Palmachim
Palmachim
Palmachim is a kibbutz in central Israel. Located about ten kilometers south of the Tel Aviv area along the coast of the Mediterranean Sea, among the sand dunes, it falls under the jurisdiction of Gan Raveh Regional Council...

 
May 2007 45 NIS 2.90 >- Hadera
Hadera
Hadera is a city located in the Haifa District of Israel approximately from the major cities of Tel Aviv and Haifa. The city is located along of the Israeli Mediterranean Coastal Plain...

 
December 2009 127 NIS 2.60

|+ Israeli water desalination facilities under construction
|-
! Location!! Opening !! Capacity
(mln m3/year) !! Cost of water
(per m3) !!Notes
|->
Ashdod  2012 100 (expansion up to 150 possible) NIS 2.40 >- Soreq  2013 150 (expansion up to 300 approved) NIS 2.01 – 2.19

Maldives


Maldives
Maldives
The Maldives , , officially Republic of Maldives , also referred to as the Maldive Islands, is an island nation in the Indian Ocean formed by a double chain of twenty-six atolls oriented north-south off India's Lakshadweep islands, between Minicoy Island and...

 is a small island nation and some of the islands of Maldives depend on desalination as a source of water.

Oman


A pilot Seawater Greenhouse was built in 2004 near Muscat, Oman. In collaboration with Sultan Qaboos University
Sultan Qaboos University
Sultan Qaboos University, located in the city of Al Khoudh, in the Capital Region of Muscat, Oman, is the only public university in the Sultanate of Oman. Named after Qaboos bin Sa’id Al ‘Bu Sa’id, the Sultan of Oman, the university opened in 1986. At the time, it comprised five colleges:...

, providing an opportunity to develop a sustainable horticultural sector on the Batinah coast
Al Batinah Region
Al Bāţinah is one of the regions of Oman.Al Batinah Region, otherwise known as Al Batinah, occupies an important location on the coast of Gulf of Oman. It lies between Khatmat Malahah in the north and Ras AL Hamra in the south and confined between the Al Hajar Mountains in the west and the Gulf...

.

Saudi Arabia


The Saline Water Conversion Corporation of Saudi Arabia provides 50% of the municipal water in the Kingdom, operates a number of desalination plants, and has contracted $1892 million to a Japanese-South Korean consortium to build one capable of producing a billion litres a day, opening at the end of 2013. They currently operate approximately 14 plants in the Kingdom; one example at Shoaiba cost $1060 million and produces 450 million litres a day.

Lanzarote, Canary Islands


Lanzarote
Lanzarote
Lanzarote , a Spanish island, is the easternmost of the autonomous Canary Islands, in the Atlantic Ocean, approximately 125 km off the coast of Africa and 1,000 km from the Iberian Peninsula. Covering 845.9 km2, it stands as the fourth largest of the islands...

 is the easternmost of the autonomous Canary Islands. It is of volcanic origin and has only very limited natural water supplies. A commercial desalination plant was installed in 1964 as a private initiative. This served the whole island and started off the tourism industry. In 1974 the venture was injected with investments from local and municipal governments and a larger infrastructure was put in place. In 1989 INALSA was formed as the Lanzarote Island Waters Consortium. The plant has been inspected by foreign visitors from places with interest in desalination.

Tenerife, Canary Islands


A prototype Seawater Greenhouse
Seawater Greenhouse
The Seawater Greenhouse is a technology that enables the growth of crops in arid regions, using a greenhouse structure, seawater and solar energy...

 was constructed in Tenerife in 1992.

El Prat del Llobregat, Catalonia


El Prat
El Prat de Llobregat
El Prat de Llobregat , commonly known as El Prat, is a municipality in the comarca of Baix Llobregat inCatalonia, Spain. It is situated in the delta of the Llobregat river on the right bank, bordering the coast of the Mediterranean Sea between Barcelona and Viladecans. More than a quarter of the...

, near Barcelona, has a desalination plant completed in 2009 and meant to provide water to the Barcelona metropolitan area, specially during the periodic severe droughs that put the drinking water provision under serious stress.

United Arab Emirates (Abu Dhabi)

  • Taweelah A1 Power and Desalination Plant has an output 385000000 litres (813,650,734.6 US pt) per day of clean water.
  • Umm Al Nar Desalination Plant has an output of 394000000 litres (832,671,141.4 US pt) per day of clean water.
  • Fujairah F2 is to be completed by July 2010 will have a water production capacity of 492000000 litres (1,039,782,237.5 US pt) per day.
  • A Seawater Greenhouse
    Seawater Greenhouse
    The Seawater Greenhouse is a technology that enables the growth of crops in arid regions, using a greenhouse structure, seawater and solar energy...

     was constructed on Al-Aryam Island, Abu Dhabi, United Arab Emirates in 2000.

Jersey Desalination Plant


Jersey Water commissioned the first desalination plant in the British Isles in 1970. The plant was built in an abandoned quarry close to the sea at La Rosière, Corbiere, at the south-west corner of the Island.
Sea water was pumped into a deep pond (quarry pool) within the old quarry before being abstracted for desalination.

The original desalination plant used a multi-stage flash (MSF) distillation process, whereby the sea water was boiled under vacuum, evaporated and condensed into a fresh water distillate.

By 1997 the MSF plant had reached the end of its operational life and it was decided to replace this important standby water resource with a modern plant using the Reverse Osmosis (RO) process, giving a number of significant operational benefits.

On Friday 9th July 1999, General Sir Michael Wilkes KCB CBE, Her Majesty’s Lieutenant Governor of Jersey, officially opened the new RO desalination plant at La Rosière.

Beckton Desalination Plant


The first large scale water desalination plant in the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

, the Thames Water Desalination Plant, has been built in Beckton
Beckton
Beckton is part of the London Borough of Newham, England, located east of Charing Cross.Its boundaries are the A13 trunk road to the north, Barking Creek to the east, the Royal Docks to the south, and Prince Regent Lane to the west. The area around Prince Regent Lane is also known as Custom House...

, east London for Thames Water
Thames Water
Thames Water Utilities Ltd, known as Thames Water, is the private utility company responsible for the public water supply and waste water treatment in large parts of Greater London, the Thames Valley, Surrey, Gloucestershire, Wiltshire, Kent, and some other areas of in the United Kingdom...

 by Acciona
Acciona
Acciona, S.A., is a Spanish conglomerate group dedicated to civil engineering, construction and infrastructure.The company was founded in 1997 through the merger of Entrecanales y Tavora and Cubiertas y MZOV. The company's headquarters is in Alcobendas, Community of Madrid, Spain. The company's U.S...

 Agua

El Paso (Texas) Desalination Plant


Brackish groundwater has been treated at the El Paso plant since around 2004. Producing 27500000 gallons (104,098,830 l) of fresh water daily (about 25% of total freshwater deliveries) by reverse osmosis, it is a crucial contribution to water supplies in this water-stressed city.

Tampa Bay Water Desalination Project


The Tampa Bay Water
Tampa Bay Water
Tampa Bay Water is a regional wholoesale drinking water utility that serves customers in the Tampa Bay, Florida region. The agency is a special district of the state created by interlocal agreement among six member governments...

 Desalination project was originally a private venture led by Poseidon Resources. This project was delayed by the bankruptcy of Poseidon Resources' successive partners in the venture, Stone & Webster, then Covanta (formerly Ogden) and its principal subcontractor Hydranautics. Poseidon's relationship with Stone & Webster through S & W Water LLC ended in June 2000 when Stone & Webster declared bankruptcy and Poseidon Resources purchased Stone & Webster's stake in S & W Water LLC. Poseidon Resources partnered with Covanta and Hydranautics in 2001, changing the consortium name to Tampa Bay Desal. Through the inability of Covanta to complete construction bonding of the project, the Tampa Bay Water agency was forced to purchase the project from Poseidon on May 15, 2002, and underwrite the project financing under its own credit rating. Tampa Bay Water then contracted with Covanta Tampa Construction, which produced a project that did not meet required performance tests. Covanta Tampa Construction's parent company filed bankruptcy in October 2003 to prevent losing the contract with Tampa Bay Water. Then, Covanta Tampa Construction filed bankruptcy prior to performing renovations that would have satisfied contractual agreements. This resulted in nearly six months of litigation between Covanta Tampa Construction and Tampa Bay Water. In 2004, Tampa Bay Water hired a renovation team, American Water/Acciona Aqua, to bring the plant to its original, anticipated design. The plant was deemed fully operational in 2007 and is designed to run at a maximum capacity of 25 million USgals (94,635.3 m³) per day. Nevertheless, the plant continues to be set with problems limiting it to producing only about half that amount (14 million USgals (52,995.8 m³) per day in 2009.

Yuma Desalting Plant (Arizona)


The Yuma Desalting Plant was constructed under authority of the Colorado River Basin Salinity Control Act of 1974 to treat saline agricultural return flows from the Wellton-Mohawk Irrigation and Drainage District. The treated water is intended for inclusion in water deliveries to Mexico thereby preserving the like amount of water in Lake Mead. Construction of the plant was completed in 1992 and it has operated on two occasions since then. The plant has been maintained, but largely not operated due to surplus and then normal water supply conditions on the Colorado River. An agreement was reached in April 2010 between the Southern Nevada Water Authority
Southern Nevada Water Authority
The Southern Nevada Water Authority was formed in 1991 to manage Southern Nevada's water needs on a regional basis. The Authority comprises seven member agencies including the City of Henderson, City of Las Vegas, City of North Las Vegas, Big Bend Water District , Clark County Water Reclamation...

, the Metropolitan Water District of Southern California
Metropolitan Water District of Southern California
The Metropolitan Water District of Southern California is the largest supplier of treated water in the US. The name is usually shortened to the "Metropolitan Water District" or simply "MWD". It is a cooperative of 14 cities and 12 municipal water districts that indirectly provides water to 18...

, the Central Arizona Project and the U.S. Bureau of Reclamation to underwrite the cost of running the plant in a year long pilot project.

Trinidad and Tobago


The Republic of Trinidad and Tobago is using desalination to free up more of the island's water supply for drinking purposes. The desalination facility, opened in March 2003, is considered to be the first of its kind. It is the largest desalination facility in the Americas and will process 28800000 gallons (109,019,865.6 l) of water a day and sell water at the price of $2.67 per 1000 gallons (3,785.4 l). This facility will be located at Trinidad's Point Lisas
Point Lisas
Point Lisas is the site of the Point Lisas Industrial Estate and the Port of Point Lisas, both of which are managed by Plipdeco...

 Industrial Estate, a park of more than 12 companies in various manufacturing and processing functions and will allow for easy access to water for both factories and residents in the country.

In nature



Seabirds distill sea water, by using Countercurrent exchange
Countercurrent exchange
Countercurrent exchange is a mechanism occurring in nature and mimicked in industry and engineering, in which there is a crossover of some property, usually heat or some component, between two flowing bodies flowing in opposite directions to each other. The flowing bodies can be liquids, gases, or...

 in a gland with a Rete mirabile
Rete mirabile
A rete mirabile is a complex of arteries and veins lying very close to each other, found in some vertebrates. The rete mirabile utilizes countercurrent blood flow within the net...

. The gland secretes highly concentrated brine stored near the nostrils above the beak. The bird then "sneezes" the brine out to the sea. As freshwater is not available in their environment, seabirds like pelican
Pelican
A pelican, derived from the Greek word πελεκυς pelekys is a large water bird with a large throat pouch, belonging to the bird family Pelecanidae....

s, petrel
Petrel
Petrels are tube-nosed seabirds in the bird order Procellariiformes. The common name does not indicate relationship beyond that point, as "petrels" occur in three of the four families within that group...

s, albatross
Albatross
Albatrosses, of the biological family Diomedeidae, are large seabirds allied to the procellariids, storm-petrels and diving-petrels in the order Procellariiformes . They range widely in the Southern Ocean and the North Pacific...

es, gull
Gull
Gulls are birds in the family Laridae. They are most closely related to the terns and only distantly related to auks, skimmers, and more distantly to the waders...

s and tern
Tern
Terns are seabirds in the family Sternidae, previously considered a subfamily of the gull family Laridae . They form a lineage with the gulls and skimmers which in turn is related to skuas and auks...

s possess this gland which allows the birds to drink the salty water from their environment while they are hundreds miles away from land.


Mangrove
Mangrove
Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...

s are trees which grow in sea water. Mangroves are able to secrete the salt by trapping it into parts of the root, which are then eaten by animals (usually crabs). Additional salt removal is done by storing it in leaves which then fall off. Some types of mangrove have glands on the leaf, which work in a similar way to the seabird desalination gland. Salt is extracted to the leaf exterior as small crystal
Crystal
A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...

s, which then fall off the leaf.

Willow
Willow
Willows, sallows, and osiers form the genus Salix, around 400 species of deciduous trees and shrubs, found primarily on moist soils in cold and temperate regions of the Northern Hemisphere...

 trees and Reed
Reed (plant)
Reed is a generic polyphyletic botanical term used to describe numerous tall, grass-like plants of wet places, which are the namesake vegetation of reed beds...

s are known to uptake salt and other contaminants, effectively desalinating the water. This is used in artificial constructed wetland
Constructed wetland
A constructed wetland or wetpark is an artificial wetland, marsh or swamp created as a new or restored habitat for native and migratory wildlife, for anthropogenic discharge such as wastewater, stormwater runoff, or sewage treatment, for land reclamation after mining, refineries, or other...

s, for treating sewage
Sewage
Sewage is water-carried waste, in solution or suspension, that is intended to be removed from a community. Also known as wastewater, it is more than 99% water and is characterized by volume or rate of flow, physical condition, chemical constituents and the bacteriological organisms that it contains...



Rain
Rain
Rain is liquid precipitation, as opposed to non-liquid kinds of precipitation such as snow, hail and sleet. Rain requires the presence of a thick layer of the atmosphere to have temperatures above the melting point of water near and above the Earth's surface...

 and Dew
Dew
[Image:Dew on a flower.jpg|right|220px|thumb|Some dew on an iris in Sequoia National Park]]Dew is water in the form of droplets that appears on thin, exposed objects in the morning or evening...

 are the outcome of large scale desalination through evaporation, in what is known as the water cycle. Fresh water floats above sea water, so during storms or in lakes where there is undersea volcanic activity causing the water to boil and then condensate, large bodies of freshwater can be found at the sea or lake surface, covering the more salty seawater below. Freshwater on the surface of seawater is common at estuaries
Estuary
An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....

.

See also


  • Brine
    Brine
    Brine is water, saturated or nearly saturated with salt .Brine is used to preserve vegetables, fruit, fish, and meat, in a process known as brining . Brine is also commonly used to age Halloumi and Feta cheeses, or for pickling foodstuffs, as a means of preserving them...

  • Dewvaporation
    Dewvaporation
    Dewvaporation is a novel desalination technology developed at Arizona State University as an energy efficient tool for freshwater procurement and saline waste stream management...

  • Salinity control
    Salinity control
    Soil salinity control relates to controlling the problem of soil salinity and reclaiming salinized agricultural land.The aim of soil salinity control is to prevent soil degradation by salinization and reclaim already salty soils...

  • Soil desalination model
    SaltMod
    SaltMod is computer program for the prediction of the salinity of soil moisture, groundwater and drainage water, the depth of the watertable, and the drain discharge in irrigated agricultural lands, using different hydrologic conditions, varying water management options, including the use of...

  • Soil salinity
  • Soil salinity and groundwater model
    SahysMod
    SahysMod is a computer program for the prediction of the salinity of soil moisture, groundwater and drainage water, the depth of the watertable, and the drain discharge in irrigated agricultural lands, using different hydrogeologic and aquifer conditions, varying water management options, including...

  • Spragg Bags
  • Pumpable ice technology
    Pumpable ice technology
    Pumpable ice technology is a technology to produce fluids or secondary refrigerants also called coolants with a viscosity of water or jelly and the cooling capacity of ice...

  • Seawater Greenhouse
    Seawater Greenhouse
    The Seawater Greenhouse is a technology that enables the growth of crops in arid regions, using a greenhouse structure, seawater and solar energy...



Further reading


Articles


External links