Desalination

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Desalination refers to any of several processes that removes the excess salt and minerals from water in order to obtain fresh water suitable for animal consumption or for irrigation, sometimes producing table salt as a byproduct.

One way to remove brine from the water is putting water under pressure and pumping ethane through it. Almost immediatly crystals appear at the top made of pure water and ethane. These crystals can be melted and then the water allowed to go into a container. Because of the structure of the molecules of this substance it only picks up water and ethane, leaving the salt behind.

Desalination of sea water has long been used on ships, submarines and islands, where cost is not the dominating concern.

Desalination for brackish water is already commonplace in the U.S., where it is used to meet treaty obligations for river water entering Mexico.

Desalination of ocean water is common in the Middle East, where a number of countries use oil-fired stills to provide city drinking water.

The price of desalination is rapidly declining. A modern, large, efficient plant is within 20% of the cost of developing a new, local source of fresh water. Desalination stills now control pressure, temperature and brine concentrations to optimize the water extraction efficiency. Other methods of desalination include reverse osmosis and pressure barrier osmosis. Nuclear-powered desalination could be very economical on a large scale.

See also: Soil salination

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