| 摘要 |
<p>PURPOSE:To control stably concn. of dissolved oxygen (DO) and the amt. of total activated sludge by interlocking the control of flow rate of feed air to an aeration tank and the control of flow rate of returned sludge from a settling basin, and compensating interference of the low rate of the feed air and the flow rate of the returned sludge with each other. CONSTITUTION:Filthy water is introduced into an aeration tank 1-1 through a channel passage A, and a mixture of the filthy water and the activated sludge flowed therefrom is introduced into a settling basin 1-2 through a channel passage A1, and the solid component is separated from the liquid, and the supernatant liquid is discharged through a channel passage A2. A part of the activated sludge 1-8 precipitated in the settling basin 1-2 is withdrawn through a drawing pipe 1-9, and a part of the drawn sludge is returned to the aeration tank 1-1 through a channel passage B, and a part thereof is discharged through a channel passage C to the outside as excess sludge. Air is fed to the aeration tank 1-1 from an air feeding device 1-5 through an air dispersing device 1-6, and the flow rate of the feed air QA* is controlled to a set value QA by a controller 5.</p> |
