| 摘要 |
PURPOSE:To increase a filtration area, by providing flow passage forming plates for forming raw water passages in a filter material layer so as to arrange the same along the inner wall of a filter tank in a multi-stage fashion. CONSTITUTION:Raw water is poured into raw water chambers 6, 8 through a raw water supply pipe 42 while stored water in said raw water chambers 6, 8 is permeated through a filter material layer 4 from the upper and the lower part thereof to be filtered. In addition, the part of stored raw water is flowed into a raw water flow passages 18 from each distribution ports through a raw water distributing pipe 10 and further permeated toward a water collecting strainer 24 from said water flow passages 18 to be filtered through the peripheral side surface of the filter material layer 4. As mentioned above, a purified filtrate by filtering action in the peripheral side surfaces and the upper and the lower surfaces of the filter material layer 4 is collected through a water collecting pipe 52 from the water collecting strainer 24. As is apparent from the foregoing, by increasing a filtration area, a filtration speed can be increased and filtering efficiency and capacity can be enhanced. |
