Forum Index > Chemistry Questions > Desalination of water
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Bill Mac 3 years ago
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Desalination is the removing of salts from water. Effective for household
purposes: Hmm, not if you live in the "industrialized" countries of the world.
The energy expended on the process would rapidly use up your fuel reserves.
Simplest chemical method? I would say that the simpliest method is physical -
heat the water to vapor form and then cool the vapors back to a liquid state.
Reverse osmosis is the simplest "chemical" method.
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kim_kyocera 3 years ago
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Desalination is a process that removes salts from water. Through distillation
and reverse osmosis, water treatment plants can remove most of the salt and
impurities from saline water, providing a clean and ingestible supply. At this
point in technological advances, the cost of desalination is still higher than
the cost of transporting freshwater from other sources, except in desert
regions like West Asia. Distillation is one method of desalination.
Distillation uses evaporation to separate impurities, such as salt, from pure
water. The water must be heated until it evaporates, so the pure water rise as
steam and particulates stay behind in brine water. The steam condenses in
another collection container while brine is ejected. Distillation has the
advantage of using thermal energy, such as sunlight, thus saving electricity
costs. However, it creates less fresh water as a percentage of impure water,
the recovery rate, than reverse osmosis. Another common method of desalination
is reverse osmosis. In reverse osmosis, the feedwater can be either saltwater
or recovered "gray" water from a city's waste supply. The force of a fan
presses feedwater through membranes with pores that let water molecules to
permeate, but don't allow salt and pollutants through. A series of filtering
membranes, with progressively sensitive membranes, are more effective and don't
clog as easily. Reverse osmosis requires a lot of electricity to power the
fans, as well as chemical treatment of gray water, but boasts a recovery rate
of close to 50%. If we are to continue our current patterns of usage, countries
all over the globe must rethink their drinking water sources. Especially in
desert climates bordering an ocean, desalination can hold the answer. Its
technology is still being perfected, but there are many research organizations
working to minimize the cost, educate the public, encourage desalination plant
construction, and eliminate any health hazards associated with reclaimed or
contaminated water.
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Bill Mac 3 years ago
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Have a look at this article oh Yahoo:
http://dsc.discovery.com/news/2008/08/27/desalination-california-print.html
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