Desalting refers to a water treatment process that removes salts from water. It is also called desalination or desalinization. Desalting can be done in a number of ways, but the result is always the same: drinking water is produced from brackish (somewhat salty) water or seawater. Desalting technologies can be used for a number of applications, but the purpose of this report is to discuss the use of desalting to produce drinking water from saline water for domestic or municipal purposes. Throughout history, people have continually tried to treat salty water so that it could be used for drinking and agriculture. Of all the globe’s water, 94 percent is salt water from the oceans and 6 percent is fresh. Of the latter, about 27 percent is in glaciers and 72 percent is underground.
While this salt water is important for transportation and fisheries, it is too salty to sustain human life or farming. Desalting techniques have increased the range of water resources available for use by a community. Until recently, only water with a dissolved solid (salt) content generally below about 1,000 milligrams per liter (mg/L) was considered acceptable for a community water supply. This limitation sometimes restricted the size and location of communities around the world and often led to hardship for many who could not afford to live near a ready supply of fresh water. The application of desalting technologies over the past 50 years has changed this in many places. Villages, cities, and industries have now developed or grown in many of the arid and water-short areas of the world where sea or brackish waters are available and have been treated with desalting techniques.
This change has been very noticeable in parts of the arid Middle East, Nor...
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...proving more economical than available conventional sources. The use of desalination technologies, especially for softening mildly brackish waters is rapidly increasing in the USA.
There is no “best ”method of desalination. Generally, distillation and reverse osmosis are used for seawater desalting, while reverse osmosis and electrodialysis are used to desalt brackish water. However, the selection of a process should depend on a careful study of site conditions and the application at hand. Local circumstances will always play a significant role in determining the most appropriate process for an area.
The “best ”desalination system should be more than economically reasonable in the study stage. It should work when it is installed and continue to work and deliver suitable amounts of fresh water at the expected quantity, quality, and cost for the life of a project.
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