TREATMENT OF SELENIUM-CONTAINING WATER AND TREATING DEVICE THEREFOR

PROBLEM TO BE SOLVED: To surely insolubilize soluble selenium to be removed without making a biologically treating reaction vessel large-sized by preventing the obstruction of the reduction reaction of selenium due to the denitrification reaction in a biological treating reaction vessel in the case of removing soluble selenium from a selenium-containing water, in which soluble selenium and nitrate nitrogen and/or nitrite nitrogen are coexisted, by biological treatment. SOLUTION: In a nitrogen removing means 6 at first, the nitrate nitrogen and/or nitrite nitrogen contained in the selenium-containing water is removed. Next, in a biologically treating means 10, the soluble selenium contained in the selenium-containing water is reduced into insoluble molecular selenium to be removed by biologically treating the selenium-containing water finished in the treatment by the nitrogen removing means 6 under facultative anaerobic condition. As the nitrogen removing means 6, the removing treatment of the nitrate nitrogen and/or nitrite nitrogen is preferably performed by one or more kinds of methods selected from the ion exchange method, the catalytic method, the reverse osmosis membrane method, electric dialysis and the electrolytic reducing method.