| 摘要 |
<p>PURPOSE:To eliminate the back-load trouble of an anaerobically digested separated liquid, by guiding a nitrated liquid mixture to a flotation concn. process and floating, concentrating and separating sludge in the liquid mixture by using nitrogen gas generated by the denitrification phenomenon of NOx-N in the liquid mixture. CONSTITUTION:An anaerobically digested separated liquid 17 is mixed with the excessive activated sludge 10 obtained in a final precipitation basin 7 and receives aeration based on air supplied by a blower 19 not only to biologically nitrate NH3-N in the separated liquid 17 but also oxidize BOD therein. In this case, NH3-N is oxided to NOx-N while the liquid mixture is flowed into a flotation concn. tank 20 where NOx-N is biologically denitrified and formed N2 gas is adhered to the surface or interior of sludge floc. As a result, the sludge component in the liquid is floated and conc. to form high conc. froth 21. The biological denitrification of NOx-N is enabled even by an endogenous respiration type but an org. carbon source may be added from the outside.</p> |
