Filtration method and apparatus having a filtrate collection chamber within the filter bed

In a down-flow filter apparatus for filtration/removal of particulate and/or soluble matter from a liquid, which apparatus includes a vertical column, a bed of filter medium contained within said column, means for introducing a liquid to be filtered at the top of said column and means for concurrently transporting a portion of the filtrate and a portion of the filter medium from the bottom region of said column to effect cleaning and regeneration of said medium, wherein the improvement comprises:

• (a) a filtrate collection chamber, located within the vertical column and immersed within a bed of filter medium in said column, said collection chamber having a closed top, and closed sides, and an open bottom and further provided with means for collection of filtrate;
• (b) a bed of filter medium within said column, said bed comprising particulate materials capable of removal of suspended and/or dissolved matter, and surrounding the filtrate collection chamber;
• (c) a means for forming filtrate cavity with the bed of filter medium, said cavity defined, on its upper boundary by the open bottom of the filtrate collection chamber and, in its lower and lateral bounderies by the filter medium;
• (d) means for introducing a liquid to be filtered into the vertical column containing the filter medium above or near the top of the bed of filter medium located within said vertical column;
• (e) means for injecting a pressurized fluid, consisting essentially of a liquid, a gas, and mixtures thereof, into the vertical column containing the filter medium, said point of injection being below the level of the open bottom of the collection chamber, so as to effect localized agitation of the filter medium and thereby allow for its localized withdrawal at or near the point of injection of the pressurized fluid by medium withdrawing means;
• (f) means for continuous withdrawal of a portion of the filter medium and a portion of the filtrate, from the column at or near the level of injection of the pressurized fluid, so as to effect concurrent withdrawal of filterate by the collection chamber, and of the filter medium, by medium withdrawal means from the bottom of the column to the top of the column;
• (g) means for return of filter medium to the top of the bed of filter medium filter once it has been washed and contaminants removed therefrom.

In a downflow filter aparatus for filtration/removal of particulate and/or soluble matter from a liquid, which apparatus includes a vertical column, a bed of filter medium contained within said column, means for introducing a liquid to be filtered at the top of said column and means for concurrently transporting a portion of the filtrate and a portion of the filter medium from the bottom region of said column to effect cleaning and regeneration thereof, wherein the improvement comprises;

• (a) a filtrate collection chamber having an open bottom, said open bottom being disposed within the bed of filter medium;
• (b) means for injecting a pressurized fluid, consisting essentially of a liquid, a gas, and mixtures thereof, into the vertical column containing the filter medium, said point of injection being below the level of the open bottom of the collection chamber, so as to effect localized agitation of the filter medium and thereby allow for its localized withdrawal at or near the point of injection of the pressurized fluid by medium withdrawing means;
• (c) means for continuous withdrawal of a portion of the filter medium and a portion of the filtrate, from the column at or near the level of injection of the pressurized fluid, so as to effect concurrent withdrawal of filterate by the collection chamber, and of the filter medium, by medium withdrawal means from the bottom of the column to the top of the column;
• and
• (d) a means for forming filtrate cavity, within the bed of filter medium, defined on its upper boundary by the open bottom of the filtrate collection chamber and its lower and lateral bounderies by the filter medium, said cavity being formed in the process of inertial compaction of the filter medium within the filter bed by the continuous withdrawal of a portion of the filter medium and a portion of the filtrate below the level of the open bottom of the collection chamber.

An apparatus for filtering a liquid comprising:

• a) a vessel having substantially cylindrical side walls and a conical base wall with the narrow end of said conical base wall facing downward;
• b) a vertical column of filter media contained in and substantially defined by said vessel;
• c) a filtrate collection chamber fixedly located in said vertical column of filter media, said filtrate collection chamber comprising a liquid-impervious top wall attached to liquid-impervious side walls, said filtrate collection chamber having an open bottom;
• d) a feed pipe for introducing a liquid to be filtered at the top of said vertical column of filter media, whereby said liquid passes downward through said vertical column of filter media, past said filtrate collection chamber and then upward through said vertical column of filter media into said filtrate collection chamber;
• e) a filtrate outlet pipe adapted to remove filtrate from said filtrate collection chamber and to deliver it outside said vessel;
• f) a straight vertical air lift tube within said vessel and extending from a position spaced from said conical base wall within said media column at a bottom end thereof, to a position above said media column at a top end thereof;
• g) a media cleaning means functionally connected with said top end of said air lift tube and adapted to receive the output of said air lift tube;
• and,
• h) an air supply tube within said air lift tube and adapted to supply air to raise portions of filter media from the bottom to the top of said air lift tube.