Desalination: Is it the Answer

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Desalination Is it the Answer?
This Saudi Arabia site uses solar power to pump
salt water, which is then turned into fresh water
via a desalination system.
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What is Desalination?

• A process that removes dissolved minerals
  (including but not limited to salt) from sea
  water, brackish water, or treated waste water.
• There are multiple methods reverse osmosis
  (RO), distillation, electodialysis, and vacuum
  freezing.
• Both RO and distillation are being considered by
  municipalities and water districts all over
  California.
• From Chp. 1Seawater Desalination in California,
  the Calif. Coastal Commission

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From the California Coastal Commission
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Desalination Plants
Distillation Plant in Kuwait
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Using Osmosis to Purify Water
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Reverse Osmosis
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Desalination using Reverse Osmosis
Using Reverse Osmosis, feedwater is pumped at
high pressure through a permeable membrane which
separates salt from water. The pre-treatment
removes particles that could clog the membrane.
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Typical Cost for a Reverse Osmosis Desalination
PlantCalifornia Coastal Commission
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DistillationFeedwater is heated and then
evaporated to separate out dissolved minerals
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Deionization
Requires the flow of water through two ion
exchange materials. Step 1 Passage through the
first material removes Ca and Mg ions and all
other metallic ions in solution and replaces them
with H. As metal ions affix to the exchange
material, it releases its H on a chemically
equivalent basis. Fe would be replaced by 3
H. What do you predict about the pH of the
treated water at this point? Step 2 Removes
the anions left in the water. The anion exchange
material replaces them with hydroxyl anions. H
OH- gt H20 The result is pure water
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Note deionization detail
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Electrodialysis
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Vacuum Freezing
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What is wrong with this picture? What is right?
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Welcome to the Imperial ValleyLooks like just
the place for agriculture, doesnt it?
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You decide
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Time is running out for the Salton Sea
http//www.lanl.gov/orgs/d/d4/enviro/ss.html