Apparatus for filter backwashing

Claim 1

Apparatus for filtering liquid wherein the liquid to be filtered flows downward through the apparatus, said apparatus comprising: (a) a vessel for containing a bed of particulate filter media, said vessel having an inlet for admitting liquid to be filtered and an outlet for removing filtered liquid; (b) water backwashing means for admitting backwashing water below the bed of filter media in said vessel to flow upward through the bed of filter media, said water backwashing means comprising a header disposed in said vessel, a plurality of laterals disposed in said vessel below the bed of filter media and above said header, each of said laterals being in liquid flow communication with said header so that a substantially uniform water level can be maintained in all of said laterals, a plurality of nozzles mounted on each of said laterals, each of said nozzles comprising a collector and a hollow pipe, said collector being a port-defining structure, a proximal end of said pipe being attached to said collector, said pipe having an apertured portion adjacent said proximal end, said collector and pipe of each of said nozzles being configured to permit passage of backwashing water upward from the lateral on which the nozzle is mounted via said pipe through a port defined by said collector into the bed of filter media, a distal end of the pipe of each of said nozzles extending downward into the lateral on which the nozzle is mounted; (c) air backwashing means cooperatively connected to said water backwashing means for admitting backwashing air into said vessel below the bed of filter media, said air backwashing means comprising a manifold, an air supply means to convey a stream of pressurized air to said manifold, and a distribution plenum, said manifold and said distribution plenum being in fluid communication with each other, said manifold and said distribution plenum being disposed below said laterals, a plurality of conduits, each lateral being interconnected with said distribution plenum by one of said conduits, each conduit extending into one of said laterals to an elevation above the distal ends of the pipes that extend downward into the laterals, said conduits permitting passage of backwashing air from said distribution plenum into said laterals and thence through the apertured portions of said pipes into said nozzles for passage into the bed of filter media, whereby the stream of pressurized air provides cushions of air in said manifold, said distribution plenum and said laterals, so that a substantially uniform pressure of backwashing air passing into the bed of filter media from said nozzles can be maintained for all of said nozzles.

Claim 6

An apparatus for filtering a liquid, said apparatus comprising: (a) a vessel for receiving said liquid to be filtered, said vessel having inlet means and outlet means, said vessel also having a bottom through which filtered liquid can be removed by valve means; (b) a floor disposed within said vessel above and spaced apart from said bottom, said floor serving to support a bed of filter media; (c) a plurality of laterals horizontally disposed in said floor beneath said filter media; (d) a plurality of nozzles connected to each lateral, each nozzle comprising a port-defining collector and a hollow pipe, a proximal end of said pipe being attached to said collector, said pipe having an apertured portion adjacent said proximal end, said nozzle serving to permit passage of backwashing water upward from said lateral into said bed of filter media, a distal end of said pipe extending downward into said lateral; (e) header means connected to said laterals to provide liquid-flow communication between said outlet means of said vessel and said laterals, said header means being disposed below said laterals and providing liquid communication among said laterals so that a substantially uniform water level can be maintained in all of said laterals; (f) a distribution plenum disposed below said laterals; (g) conduit means comprising a plurality of conduits, said conduits being connected one to each lateral and to said distribution plenum, said conduit means providing fluid communication between said laterals and said distribution plenum, each conduit extending into a corresponding lateral to an elevation above the distal ends of the pipes extending downward into said corresponding lateral; (h) a manifold disposed below said laterals, said manifold being in fluid communication with said distribution plenum; and (i) air introduction means connected to said manifold for introducing pressurized backwashing air into said manifold, so that cushions of air can be formed in said manifold, in said distribution plenum and in said laterals as said backwashing air passes from said manifold into said distribution plenum and thence via said conduit means into said laterals and thence through said apertured portions of said pipes into said nozzles for passage into the bed of filter media, said cushions of air serving to provide substantially uniform air pressure for said backwashing air from said nozzles.

Claim 7

An apparatus for filtering a liquid, said apparatus comprising: (a) a vessel for receiving said liquid to be filtered, said vessel having inlet means and outlet means, said vessel also having a bottom through which filtered liquid can be removed by valve means; (b) a floor disposed within said vessel above and spaced apart from said bottom, said floor serving to support a bed of filter media; (c) a plurality of laterals horizontally disposed in said floor beneath said filter media; (d) a plurality of nozzles connected to each lateral, each nozzle comprising a port-defining collector and a hollow pipe, a proximal end of said pipe being attached to said collector, said pipe having an apertured portion adjacent said proximal end, said nozzle serving to permit passage of backwashing water upward from said lateral into said bed of filter media, a distal end of said pipe extending downward into said lateral; (e) header means connected to said laterals to provide liquid-flow communication between said outlet means of said vessel and said laterals, said header means being disposed below said laterals and providing liquid communication among said laterals so that a substantially uniform water level can be maintained in all of said laterals; (f) a distribution plenum disposed below said laterals; (g) conduit means comprising a plurality of conduits, said conduits being connected one to each lateral and to said distribution plenum, said conduit means providing fluid communication between said laterals and said distribution plenum, each conduit extending into a corresponding lateral to an elevation above the distal ends of the pipes extending downward into said corresponding lateral; (h) a manifold disposed below said laterals, said manifold being in fluid communication with said distribution plenum; and (i) air introduction means connected to said manifold for introducing pressurized backwashing air into said manifold, so that cushions of air can be formed in said manifold, in said distribution plenum and in said laterals as said backwashing air passes from said manifold into said distribution plenum and thence via said conduit means into said laterals and thence through said apertured portions of said pipes into said nozzles for passage into the bed of filter media, said cushions of air serving to provide substantially uniform air pressure for said backwashing air from said nozzles.