| 摘要 |
<p>PURPOSE: To efficiently backwash a filter bed by uniformly stirring the whole thereof by a method wherein a water level is lowered to the position under a filter medium outflow preventing strip and air is discharged to a floating filter bed from below to fluidize the floating filter bed and the clogging matter in the floating filter bed is removed. CONSTITUTION: Raw water to be treated is allowed to flow in a treatment tank 1 from an inflow port 2 and purified while allowed to flow upwardly through a floating filter bed 3 to be allowed to flow out of an outflow port 4. Herein, the floating filter bed 3 is formed by packing the space partitioned by a pair of upper and lower filter medium outflow preventing strips 5, 6 with a floating filter medium 7. When the treatment tank 1 is backwashed, at first, water in the treatment tank 1 is drained from a lower discharge port 10 and a water level is lowered to the position under the upper filter medium outflow preventing strip 5. Next, air is sent from a blower 8 to be discharged from the nozzles of an air sending pipe 9 and the floating filter bed 3 is fluidized to peel the biological membrane on the floating filter medium 7. Continuously, sludge such as the peeled biological membrane is sedimented to be discharged out of a lower discharge port 10.</p> |
