Patent ID: 8333889
Filing Date: 2012-12-18
Classification: B01D

Abstract:
1. A filter system having a filter bed for filtering water or wastewater, where the filter bed is periodically washed between service runs by directing washing liquid and washing gas upwardly through the filter bed, said filter system comprising: (a) a filter bed; (b) a first flume being in fluid communication with said filter bed, said first flume being configured such that during washing of said filter bed between service runs said first flume receives a washing gas and directs said washing gas upwardly through said filter bed to assist in cleaning said filter bed between service runs, said first flume being a washing gas only flume as during washing only a washing gas is directed into said first flume and the only liquid that may be in said first flume during washing is residual liquid that may be present in said first flume from a prior service run; (c) a second flume being in fluid communication with said filter bed, said second flume being spaced from said first flume, said second flume being configured such that during washing said second flume receives a washing liquid and directs the washing liquid upwardly through said filter bed to assist in cleaning said filter bed between service runs, said second flume is a washing liquid only flume as the only washing fluid directed into said second flume during washing is a liquid; and, (d) a plurality of underdrain laterals disposed below said filter bed, each of said underdrain laterals being configured to receive a washing gas from said first flume and direct the washing gas upwardly to said filter bed and each of said underdrain laterals being configured to receive a washing liquid from said second flume and direct the washing liquid upwardly to said filter bed, at least a portion of said first flume being disposed below at least a portion of said plurality of underdrain laterals, said first flume and said second flume each having a chamber with a longitudinal axis extending traverse to a longitudinal axis of each of said plurality of underdrain laterals, said first flume and said second flume being configured such that when said filter bed is washed with simultaneous liquid and gas said first flume receives only a washing gas from a washing gas supply source and said second flume receives only a washing liquid from a washing liquid supply source, a first portion of each of said plurality of underdrain laterals forming an upper wall of said first flume, a second portion of each of said plurality of underdrain laterals forming an upper wall of said second flume, said second portion is different from said first portion; and, (e) said first flume being positioned relative to each of said plurality of underdrain laterals such that during washing the washing gas enters said first flume prior to entering any of said plurality of underdrain laterals.