Chemistry

Desalination

Water desalination processes separate dissolved salts and other minerals from water. Seawater desalination has the potential to reliably produce enough potable water to support large populations located near the coast. The most common desalination methods employ reverse-osmosis in which salt water is forced through a membrane that allows water molecules to pass but blocks the molecules of salt and other minerals. Thermal desalination uses heat, often waste heat from plants or refineries, to evaporate and condense water to purify it. The cost is very high and so it cannot be afforded by everyone who needs it, but because the desalinisation technology is improving fast, so the costs are beginning to fall, making it more affordable to countries and islands that need it. Desalination techniques are also being developed on a much smaller scale. Portable desalination kits are a prime example. Desalination is becoming more economically viable as the technology improves. Desalination plants can be provided in a wide range of outputs to cater for small isolated communities or to contribute substantially to water supplies for large cities and even for irrigation.