A granular media filter for removing impurities from water having a plurality of elongate through orifices for use in a water treatment plant used in conjunction with a porous granular bed Dirt is removed by passing water in the opposite direction at a higher rate than the forward flow

摘要

A system for backwashing filter media off a filter bed of the figure 1, including a plurality of devices for admitting a backwashing medium for passage through the bed in a direction opposite that of filtration, and a plurality of further devices for admitting a further backwashing medium for passage through the bed in the direction, each further device having a plurality of elongate through orifices adapted to allow passage, through of the further backwashing medium but not of the filter media.