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Desalination or desalinization is a process that removes minerals from saline water. More generally, desalination may also refer to the removal of salts and minerals,〔("Desalination" ) (definition), ''The American Heritage Science Dictionary'', Houghton Mifflin Company, via dictionary.com. Retrieved August 19, 2007.〕 as in soil desalination, which also happens to be a major issue for agricultural production.〔("Australia Aids China In Water Management Project." ) ''People's Daily Online'', 2001-08-03, via english.people.com.cn. Retrieved August 19, 2007.〕 Salt water is desalinated to produce fresh water suitable for human consumption or irrigation. One potential by-product of desalination is salt. Desalination is used on many seagoing ships and submarines. Most of the modern interest in desalination is focused on developing cost-effective ways of providing fresh water for human use. Along with recycled wastewater, this is one of the few rainfall-independent water sources. Due to relatively high energy consumption, the costs of desalinating sea water are generally higher than the alternatives (fresh water from rivers or groundwater, water recycling and water conservation), but alternatives are not always available and rapid overdraw and depletion of reserves is a critical problem worldwide. Quoting Christopher Gasson of Global Water Intelligence, "At the moment, around 1% of the world's population are dependent on desalinated water to meet their daily needs, but by 2025, the UN expects 14% of the world's population to be encountering water scarcity. Unless people get radically better at water conservation, the desalination industry has a very strong future indeed."〔 Desalination is particularly relevant in dry countries such as Australia, which traditionally have relied on collecting rainfall behind dams to provide their drinking water supplies. According to the International Desalination Association, in June 2011, 15,988 desalination plants operated worldwide, producing 66.5 million cubic meters per day, providing water for 300 million people. This number has been updated to 78.4 million cubic meters by 2013,〔 or 57% greater than just 5 years prior. The single largest desalination project is Ras Al-Khair in Saudi Arabia, which produced 1,025,000 cubic meters per day in 2014,〔("Desalination industry enjoys growth spurt as scarcity starts to bite" ) globalwaterintel.com.〕 although this plant in Saudi Arabia is expected to be surpassed by a desal plant in California.〔http://economictimes.indiatimes.com/slideshows/nation-world/biggest-ocean-desalination-plant-in-california-nears-completion/slideshow/46932071.cms?intenttarget=no〕 The largest percent of desalinated water used in any country is in Israel, which produces 40% of its domestic water use from seawater desalination.〔Pyper, Julia (February 7, 2014) (Israel is creating a water surplus using desalination ). ''EENews''〕 ==Methods== The traditional process used in these operations is vacuum distillation—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 equals the ambient pressure and vapor pressure increases with temperature. Thus, because of the reduced temperature, low-temperature "waste" heat from electrical power generation or industrial processes can be used. The principal competing processes use membranes to desalinate, principally applying reverse osmosis technology. Membrane processes use semipermeable membranes and pressure to separate salts from water. Reverse osmosis plant 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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Desalination」の詳細全文を読む スポンサード リンク
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