| 摘要 |
PROBLEM TO BE SOLVED: To easily and effectively remove selenium in waste water by adding a reducing agent to the waste water and bringing the waste water into contact with a catalyst containing at least one kind of metal selected from the group VIIA metals in the periodical table to remove hexavalent Se and/or quadrivalent Se from the waste water. SOLUTION: A pH controlling agent 3 and a reducing agent 4 are supplied to the source liquid containing hexavalent Se and quadrivalent Se which are difficult for treatment in a source liquid reservoir 5. The liquid from the source liquid reservoir 5 is introduced into the lower part of a reactor 8 filled with a catalyst containing at least one kind of metal selected from the group VIIA metals in the periodical table. After the hexavalent Se in the source liquid 1 is reduced by the chemical reaction, the liquid is introduced into a treated liquid tank 12 and drained. When the activity of the catalyst 9 decreases due to long-term water treatment, for example, a back washing water is periodically introduced to the upper part of the reactor 8 and discharged from the lower part of the reactor 8 through a valve 15 and a line 16 so as to wash the catalyst 9 and to discharge the crystallized single Se. |
