| 摘要 |
<p>PROBLEM TO BE SOLVED: To enable treatment at a rather low cost without leaving unstable residue by adding and mixing a compd. or mixture in a selenium-contg. waste water or a selenium-contg. sludge, controlling the mixture to specified pH with an acid or alkali, precipitating and removing selenium as an insoluble compd. SOLUTION: The following compds. are successively or simultaneously added to a selenium-contg. waste water (A) supplied to a reaction tank 1 and stirred by rotating a stirrer 3. The compds. are ferric chloride as a compd. to produce a compd. which can chemically adsorb univalent anions, sulfuric acid or its mixture as a soluble compd. to produce an anion which forms an insoluble compd. with a bivalent barium ion. and barium chloride as a barium compd. which dissolves to produce bivalent barium ton. By adding barium chloride enough for the reaction, the reaction system contains excess barium. After the pH of the system is adjusted to 5 to about 9 with an acid or alkali, selenium is completely removed although the excess bivalent barium ion remains after the reaction with selenium.</p> |
