| abstract |
A novel process for water demineralization involving the use of separate beds of weakly acidic cation exchange resin, weakly basic anionic exchange resin and a third column of weakly acidic cationic exchange resin. The first column of cation resin is buffered with a suitable base such as ammonia or an amine. When the saline feed is passed through the system, the cations of the feed are exchanged for the buffer, releasing buffered salts. The buffered salts when passed through the anion exchange column are split, releasing the buffer that is then deposited on the third cation resin column. The latter column is then used as the first separate bed during the next demineralization cycle. Thus, the buffer is internally looped, preventing contamination and also resulting in a saving of feed chemical. This process allows the efficient use of weak cation and anion exchange resins in a separate fixed-bed configuration. The process is adaptable to deionizing brackish water and tertiary waste water from sewage plants, to remove water soluble ions. |