| 摘要 |
PURPOSE:To lower the installation cost of the title apparatus by integrally constituting both an aeration tank and a carrier separation tank and raising air blown out from a diffuser while keeping it in connection with sewage. CONSTITUTION:Sewage introduced through an intake 14 in mixture with carriers 20 stuck with microorganism flows down in a spiral aeration tank 13. On the other hand, when blowing out air from a diffuser 15 and raising it in the aeration tank 13 while keeping it in connection with sewage, it is brought into contact with the carriers 20 floating in sewage and sewage in the aeration tank 13 is biologically treated with microorganism stuck on the carrier 20. When treated water contg. part of the carriers 20 flow down to the bottom of an outer tank 11, treated water is regulated to such flow velocity that the carriers 20 are settled and thereby the carriers 20 are settled on the bottom of the outer tank 11 and only treated water is introduced into an inner tank 18 to show upflow and is taken out to the outside through an overflow port 19. The settled carriers 20 are sucked with a pump P and returned to the intake 14 of sewage and again mixed into sewage.
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