| 摘要 |
<p>PROBLEM TO BE SOLVED: To surely remove both selenic acid ion and selenious acid ion by making the amt. of org. substances as a hydrogen donor to an optimum value when a selenium-contg. waste water contg. nitric acid nitrogen and/or nitrous acid nitrogen (NOx-N) is treated by anaerobic biologicaltreatment under a facultative anaerobic condition. SOLUTION: An anaerobic biotreatment is performed under a condition where at least 2-fold by wt.org. substances to the concn. of NOx-N in water to be treated exist as BOD when the concn. of NOx-N in the water to be treated is at least 5-fold by wt. of soluble selenium. For example, the concn. of NOx-N in raw water 2 is measured by a nitrogen concn. measuring means 9 and, based on this concn. of NOx-N, the amt. of addition of the org. substances to the raw water flowing in a raw water introducing pipe 8 from an org. substance addition mechanism 10 is controlled in such a way that the anaerobic biologicaltreatment is performed under a condition where at least 2-fold by wt.org. substances to the concn. of NOx-N in the raw water exist as BOD in a biologicaltreatment reaction tank 6.</p> |
