摘要 |
PROBLEM TO BE SOLVED: To safely remove hexavalent chromium at a low cost without generating harmful gas by bringing an org. material containing cellulose into contact with an acidic soln. containing hexavalent chromium. SOLUTION: Sawdust 3 is directly charged in a treatment tank 20 to collectively perform the reducing treatment and alkali treatment of a liquid to be treated. That is, sawdust 3 is charged in the strong acidic liquid to be treated in the treatment tank 20 as it is to reduce hexavalent chromium in the liquid to be treated to trivalent chromium. After hexavalent chromium is reduced to trivalent chromium by bringing sawdust 3 into contact with the liquid to be treated, an alkali agent such as sodium hydroxide or the like is added to the liquid to be treated to perform alkali treatment and chromium hydroxide is formed to be precipitated. In the alkali treatment by the addition of the alkali agent, it is pref. to adjust the pH value of the liquid to be treated to 3-5 (pref. 4).
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