| 摘要 |
A filtering device includes a cylindrical screen and a backwash tube provided in the cylindrical screen and rotatable about its axis. The backwash tube has an inlet for introducing filtered liquid in one end and an opening for discharging the filtered liquid and introducing backwash water in the other end and has backwash water injection holes formed in the axial direction at a predetermined interval. A check valve is provided on the side of the opening for discharging the filtered liquid and introducing the backwash water in the vicinity of the inlet for the filtered liquid for allowing flowing of the filtered liquid from the inlet to the backwash tube and prohibiting flowing of the backwash water from inside of the backwash tube to the inlet. Backwash tube rotation means which may be made of a blade or offset backwash water injection holes is provided for rotating the backwash tube about its axis.
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