| 摘要 |
<p>PURPOSE:To prevent the clogging of a passage by a filter material, by forming a small diameter part and enlarged parts gradually enlarged in a diameter from the small diameter part toward both end opening parts to a short tubular filter material main body opened at both ends thereof. CONSTITUTION:A short tubular filter material main body 1 made of a synthetic resin has a small diameter part 2 formed to the central part thereof in the longitudinal direction and enlarged parts 4, 4, which are enlarged in their diameters from the small diameter part to both opening parts 3, 3 in a tapered form, formed thereto. The boundaries of the small diameter part 2 and the enlarged parts 4, 4 are formed into curved surfaces and the outer or inner surface of the filter material main body 1 is formed into a sludge holding surface 6 comprising a rough surface by sand blasting. The immersion filter bed part 10 of a water treatment tank 9 is filled with a large number of the filter material main bodies 1 to perform anaerobic or aerobic treatment. Because the filter material main bodies 1 hold a mutual spot contact state at the outer peripheral surfaces thereof, the flow passages of treated water between the outer peripheral surfaces are not blocked.</p> |
