| 摘要 |
<p>PURPOSE:To decrease BOD considerably from waste water contg. thick BOD by specifying the peripheral speed of an axial flow impeller, the clearance between the axial flow impeller and a cylindrical inside cylinder, and the pressure in a pressurized aeration tank, respectively, and performing activated sludge treatment. CONSTITUTION:As a means of making efficiency as high as possible and driving power as small as possible under the conditions of assuring a max. flow rate in a pressure aeration tank 1, an impeller 23 is designed as a high efficiency axial flow pump. Delivery at a large flow rate is accomplished by forming the impeller 23 into a vane type section of the specific velocity expressed by the equationI. If the ratio between the inside diameter (d) of an inside cylinder 19 and the outside diameter da of the impeller 23 is selected at the equation II, the amt. of the liquid backflowing through the clearance between the vanes and the inside cylinder to the inflow side is slight. It is desirable to make the peripheral speed of the impeller 23 constant in order to unify the flow pattern in the tank and its adequate range is 8-15m/S.</p> |
