TREATMENT OF SELENIUM-CONTAINING WASTE WATER AND DEVICE THEREFOR

PROBLEM TO BE SOLVED: To surely insolubilize and remove soluble selenium while preventing the need to make a biological treatment reaction vessel large-sized or the obstruction to biological reaction due to the toxicity of soluble selenium even when selenium-containing waste water contains the soluble selenium in high concentration in the case of beating selenium-containing waste water by utilizing the biologically treating method. SOLUTION: As a 1st step, the selenium-containing waste water containing soluble selenium is treated with the physico-chemical selenium removing method by a physico-chemical treating means 6. Next, as a 2nd step, the treated water in the 1st step is treated with a biological treating selenium removing method by the biological treating means 22. Further, as a 3rd step, the treated water in the 2nd step is flocculation-treated by a flocculation treating means 36. In the 1st step, the selenium-containing waste water having soluble selenium concentration exceeding 500 mgSe/l is treated properly to control the soluble selenium concentration in the treated water in the 1st step to