| 摘要 |
Inorganic salts are removed from an unpotable water stream, particularly a salt-containing inland water stream. The stream is passed sequentially through anion and cation exchange beds. Periodically the anion exchange bed is regenerated with sodium hydroxide and the cation exchange bed with hydrochloric acid to form spent regenerant streams which are combined with hydrochloric acid in the presence of calcium ion to precipitate calcium salts of anions from the mixture. The soluble portion is then mixed with sodium hydroxide in the presence of carbonate ion to precipitate insoluble cations from the mixture as hydroxides or carbonates. The soluble portions, comprising essentially an aqueous sodium chloride stream, is separated into a more concentrated and less concentrated portion. The more concentrated stream is electrolyzed to provide a source of hydrochloric acid and sodium hydroxide for the above steps, while the less concentrated stream is recovered as a source of potable water.
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