| 摘要 |
A filter for removal of suspended solids from fluids utilizes pressurized air for fluidizing filter media as the latter is exposed to backwashing water. The filter includes a casing having upright walls defining an annular chamber in horizontal cross-section, and a portion of the walls have openings that are pervious to liquid and substantially impermeable to the media particles. The flow of the backwash water is directed toward the upright, outer casing wall such that the backwash water flows at a direction at an angle relative to the upward flow of the pressurized air in the bed as the particles are fluidized, to facilitate removal of the accumulated solids without enabling escape of the media particles. Desirably, pressurized air is introduced into the chamber at vertically spaced locations to insure complete fluidization. Moreover, a cylindrical conduit is disposed within the media and surrounds the upper, pressurized air outlet aperture to provide a recirculation path for a portion of the media particles. In preferred forms, the filtering media is a mixture comprised of about 60% by weight of anthracite coal and about 40% by weight of anhydrous aluminum silicate, and the mixture is substantially of a screen size ranging from -18 U.S. sieve mesh to +25 U.S. sieve mesh.
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