| 摘要 |
<p>PURPOSE:To finely correspond to the fluctuation of load and to enhance purifying efficiency by providing a flowmeter in a draft tube at a place receiving no effect of the air bubbles from an air diffusion pipe and controlling the air blow rate of a blower so as to keep the flow velocity in a filter material constant on the basis of the signal from the flowmeter. CONSTITUTION:When air is supplied to an air diffusion pipe 9 from a blower 11, sewage is sucked in a draft tube 3 from an inflow port 7 by the air lift pump action of a large number of air bubbles (b) floating from the lower end opening of the air diffusion pipe 9. The sewage is upwardly sucked to be guided toward a filter material 6 from the upper edge part of the draft tube 3 and purified during the passage through the filter material 6 to be discharged from an outflow port 8. During this period, a control circuit 14 controls the air blow rate of the blower 11 on the basis of the signal from a flowmeter 12. Therefore, the rising of purification from an operating period can rapidly be performed. Since the air blow rate automatically becomes low when inflow load is low, energy conserving operation becomes possible. further, automatic correspondence can be taken even when inflow load is large.</p> |
