| 摘要 |
PURPOSE:To wash and regenerate a filter bed in an isolated state, by using the liquid pervious filter bed having flexible fibers suspended from the entire surface thereof and a perforated plate positioned under said filter bed and raised and lowered by a float in a pressure contact state. CONSTITUTION:When raw water is sent to the space under a filter bed as an upward stream, flexible fibers 2 are compressed by a liquid pervious perforated plate 20 integrated with a float raised by buoyancy to form the filter bed and the suspended substance in raw water is filtered and collected at the under surface of this fiber filter bed. In peeling off a cake, washing and regenerating the filter fibers, the supply of the raw water is stopped and the valve 15 of the concentrate discharge pipe 16 provided in the space under the filter bed is opened while air is directly introduced into the space under the filter bed in a filter tank from an air introducing pipe 22 as a side passage without passing the same through the filter bed to lower the water level in said space and the filter fiber is washed by the filtrate remaining in the space above the filter bed in a downward stream in such a state that the perforated plate 20 is spaced apart from the fiber layer 2.
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