| 摘要 |
<p>A selenium-containing waste water is treated by biological treating means (6), chemical treating means (12), and filtration means (14) in a successive manner. In the biological treating means (6), hexavalent selenate ions and/or tetravalent selenite ions (soluble selenium) present in untreated water (16) is reduced by anaerobic biological treatment to selenium as a simple substance; thereby insolubilizing and removing the soluble selenium. In the chemical treating means (12), for example, a metal salt capable of reacting with the soluble selenium to generate an insoluble selenium compound is added to the water after the treatment by the biological treating means (6) to insolubilize and remove remaining soluble selenium. In the filtration means (14), the insolubilized compound remaining in the water after the treatment by the chemical treating means (12) is removed by filtration. This enables a large proportion of the soluble selenium to be removed from a seleniumcontaining waste water without the use of a large amount of chemicals and without producing a large amount of sludge. Therefore, it is possible to clear a waste water quality standard of at most 0.1 mg Se/l, and the running cost and the waste treatment cost can be reduced.</p> |
