Abstract: An underdrain block for a filter media system for supporting the filter media and distributing air and water backwash. The underdrain block comprising a top wall, a bottom wall and two side walls forming an open ended interior. Interior walls, known as lateral separation walls, divide the interior of the block into primary and secondary laterals. When the blocks are laid end to end, the laterals form a common distribution conduit for the transport of air and water backwash. The lateral separation walls can be angular or curved. Curved walls and specifically angled walls increase the area of the laterals. The spacing of the blocks can be approximately 18 inches and the height approximately 8 inches. The underdrain blocks are interlocking to form conduits of up to 40 feet in length.

Abstract: A filler casing houses a plurality of filter cartridges. Each cartridge has a permeable top and bottom surface and impermeable sides. Water is forced under pressure through the cartridges to accomplish filtering. Each cartridge may have a different filtering material and are removable from the casing. In this manner, the filter cartridges can be selected according to the types of impurities to be removed.

Abstract: A grout-gripping anchor for an underdrain block to be grouted to a filter floor is disclosed. Underdrain blocks have ribs extending outwardly from the exterior walls. The anchor is formed at the distant end of ribs positioned on the bottom exterior wall. The end of the rib widens to form one or more flanges or ledges so that grout covers the ledge when the underdrain block is grouted onto the filter floor. The anchor can be comprised of various shapes, including wedge-shape, rectangular shape or donut shaped.

Abstract: A method of backwashing a filter includes a) supplying a backwash liquid via a conduit toward one end of a filter bed; b) aspirating air into the backwash liquid upstream of the bed; c) introducing a mixture of air and backwash liquid into the filter bed at the one end thereof; and d) expelling backwash water and air from an opposite end of the filter bed. A related filter system includes a filter basin having a bed of filter media material therein; a filtrate channel proximate the basin; at least one tubular underdrain header in the bed and in fluid communication with the filtrate channel; and a backwash pump having a backwash water supply conduit selectively engageable with the underdrain header for supplying backwash liquid to the bed. The backwash water supply conduit includes a nozzle for aspirating air into the supply conduit at a location between the backwash pump and the bed.

Abstract: An underdrain unit of the type having air and water backwash for backflushing a granular filtration system has improved retention structure for retaining folded, perforated stainless steel underdrain plates against the floor of the tank drain. The retention structure is in the form of hollow horizontal tubes which not only hold the folded plates in place but also serve to deliver backwashing air. Thus, instead of air delivery tubes being mounted above a series of brackets that hold the folded plates in place against the floor, the air delivery in the system of the invention is via the same structural element which retains the folded plates. Embodiments are described for gravel bed systems and for sand filter systems.

Abstract: A water conditioner includes a tank, and an apparatus for backflushing a bed of particulate material in the tank, which includes a tubular casing, a vertical tube in the casing, a cap on the top end of the casing, suitable valves for causing the flow of particulate material upwardly between the casing and tube, and then through a gap between the casing and cap during a backflush operation, and distributor device including a flexible, collapsible, umbrella-shaped body which is mounted on the casing immediately below the cap, and springs for biasing the body to the open position. Inlet tubes extend outwardly from the bottom of the casing approximately the same distance as the distributor for ensuring even distribution of liquid at the bottom of the bed.

Abstract: An improved method for constructing filter underdrain systems may be provided which uses prefabricated underdrain cells. The prefabricated underdrain cells may have a one piece construction having side walls and a bottom. The side walls may include a porous plate support ledge with a ridge at the center of the ledge. The ridge helps ensure that the sealant forms a uniform and effective gasket when the porous plates are installed.

Abstract: A biological reactor including a settler assembly for reducing loss of biological material during high-turbulence treatment of liquid in the biological reactor. The settler assembly is comprised of plates, tubes, or other porous materials placed between a system of baffles and a collection trough. The settler assembly reduces turbulence near the overflow weir edge of the collection trough, thereby reducing biological material carry over with the treated liquid into the collection trough. The trough baffle settler assembly will allow higher treatment rates with the same or lower losses of biological material than experienced with previous trough-baffle designs, thereby reducing costs of construction and operation of biological reactor systems.

Abstract: An apparatus, such as a granular media filter, for treating liquid, such as wastewater, including a settler assembly for reducing media loss during high-turbulence washing of media in the granular media filter. The settler assembly is comprised of plates, tubes, or other porous materials placed between a system of baffles and a backwash trough. The settler assembly reduces turbulence near the overflow weir edge of the backwash trough, thereby reducing media carry over with the backwash water into the backwash trough. The trough baffle settler assembly will allow higher backwash rates per backwash with the same or lower media losses than experienced with previous trough-baffle designs, thereby reducing costs of construction and operation of granular media filter systems. The settler assembly is particularly adapted for use with granular media filters employing simultaneous application of air and water to produce a high turbulence backwash.

Abstract: A method of degassing biological filters utilizing a backwash system wherein the steps of opening and closing valves are reduced, flow interruption through the filter is minimized, and the process of draining down a downflow filter is eliminated. A preferred method of degassing a plurality of downflow biological filters in a water treatment system comprises the steps of maintaining the influent flow throughout the degassing process, ceasing the effluent flow out of a filter selected to be degassed to prevent draining of the selected filter, introducing a backwash water flow into the bottom, and flushing of the filter until entrapped gases are released out of the filter. The backwash flow is then ceased and the effluent flow is recommenced to return the filter to service. The steps are successively repeated and the backwash pump remains on until all filters are degassed.

Abstract: A differential pressure monitor measures the pressure at a plurality of heights in a filter bed. A preferred embodiment of the monitor comprises an elongated body, a plurality of pressure sensors located on the elongated body for obtaining the pressure readings, a control means for determining differential pressures from the pressure readings, each differential pressure being the difference in pressure between pressures measured at two different heights in the filter bed, and transmission means to transmit the pressure readings from the pressure sensors to the control means. Methods of monitoring and controlling the performance of a filter bed during filtration and during backwashing also are provided. Two such methods include measuring turbidity levels in a filter bed and obtaining water samples from a filter bed.

Abstract: A water filtration system for residential homes having at least one U-shaped filter device, in the form of a tube, containing a three-layered particulate bed of a sand layer between anthracite layers held by end screens, for removing iron and manganese contaminants. Pressure gauges, an alarm element and a clarity analyzer containing a photocell are included in the system, for monitoring and controlling the filtration system.

Abstract: A completely new type of filtration system uses a traveling plenum that travels through granular filtration media in a filter tank and backwashes a portion of the media a little at a time. A pump forces backwash water into the traveling plenum, and porous plates mounted on the top of the plenum allow the water to come to the surface of the media and loosen solids deposited at the surface during a filtration cycle. A washwater hood and waste water pump removes the loosened solids from the surface of the media. Porous plates mounted on the sides of the traveling plenum allow backwash water to fluidize surrounding media and promote the transportation of the traveling plenum in the media. Thus, filter construction is reduced to creating a tank with influent and effluent openings without the complicated cell and plenum construction of conventional traveling bridge filters. Effluent plugs, installed across effluent openings, are designed to allow water to exit the tank but retain media inside the tank.

Abstract: This invention comprises a process and apparatus for producing purified drinking water from surface or ground fresh water sources using no chemical pretreatment or coagulants, by usage of a positively-charged filtration media to attract the typically negatively-charged suspended solids present in the water source. The process, which can be portable, includes a filtration system having a filtration/recirulcation/backwash component and a disinfection step. The process further includes a system controller which receives electrical signals from float controls to control the filtration, recirculation, and backwash steps. This process produces drinking water which meets or exceeds the guidelines set by the World Health Organization for turbidity and microbiological content.

Abstract: Apparatus for treating a liquid containing suspended solids comprising a clarifying vessel and a number of filters positioned around the periphery of the clarifying vessel for receiving and filtering liquid from the clarifier. A filter may be backwashed by isolating that filter, filling the other filter cells with clarified liquid and draining them into the isolated cell to remove filter media contaminants.

Abstract: A cooling tower water treatment system removes contaminants include chlorine, calcium carbonate as calcite, and microorganisms from water in the system with redox media in a fluidized bed. The treatment system includes a treatment bed, in the form of a column, having a reaction chamber of a first diameter and a retention chamber of a second diameter, the second diameter being greater than the first diameter. Redox media, in the reaction chamber, is fluidized by water flowing in a direction countercurrent to gravity and is held in place, without the use of screens or filters, by a reduction in flow rate of the fluidizing media resulting from the larger diameter of the retention chamber. Preferably, the treatment system includes a physical filtration unit, such as an automatic backwashing sand filter, to prevent entry of particulates and scale into the reaction chamber.

Abstract: A filter media washing system for washing contaminants from filter media of a plurality of filtration vessels. Each filtration vessel has a filtration screen subdividing the filtration vessel into a filter media containing chamber and a filter media-free chamber. Each filter media containing chamber of each filtration vessel has a first fluid passage connected thereto and is located distally from the filtration screen. A second fluid passage is also positioned in each filter media containing chamber, but it is located proximate to the filtration screen. The first and second fluid passages are fluidly coupled, one to the other with a decontamination unit located fluidly therebetween for separating filter media from contamination carried therewith. The decontamination unit includes a contamination separating pump, a contamination separating chamber, a contamination separating screen and a return manifold. The return manifold has a first and second return conduit.

Abstract: A backwash sealing shoe is provided for a filtration system including a tank having an undivided filtration bed and a plurality of side-by-side headers within the bed, each header in communication with a respective port in a wall of the tank. The sealing shoe includes a hydraulic section including an opening surrounded by a seal and adapted to sealingly engage the wall in surrounding relationship to at least one of the ports; and at least one blocking section adjacent the hydraulic section on one side thereof and including a plate surrounded by a seal and adapted to sealingly engage the wall in surrounding relationship to at least one adjacent port to thereby block flow from the tank through at least one adjacent port during a backwash operation.

Abstract: A granular media filter including a settler assembly for reducing media loss during high-turbulence washing of media in the granular media filter. The settler assembly is comprised of plates, tubes, or other porous materials placed between a system of baffles and a conventional backwash trough. The settler assembly reduces turbulence near the overflow weir edge of the backwash trough, thereby reducing media carry over with the backwash water into the backwash trough. The trough baffle settler assembly will allow higher backwash rates per backwash with the same or lower media losses than experienced with previous trough-baffle designs, thereby reducing costs of construction and operation of granular media filter systems. The settler assembly is particularly adapted for use with granular media filters employing simultaneous application of air and water to produce a high turbulence backwash.

Abstract: A method for minimizing wastewater discharge generated in an ion exchange regeneration system having a cation exchange bed and an anion exchange bed, which method is characterized in that all of the segments of regenerant and displacement rinse are recirculated in a common loop, and shifted forward by one position, whereby the first segment is discarded in the subsequent cycle, and the last segment in the subsequent cycle is provide by fresh rinse, while chemicals are added as necessary, and in final rinse cycle, rinse flows through the cation exchange bed and the anion exchange bed in series, and recirculates in a loop, thereby eliminating over 90% of waste.

Abstract: Electro-magnetic filter apparatus and method of operating to separate and remove oily magnetic solids from wastewaters. The filter apparatus includes a filter assembly having an electro-magnetic coil that encircles a canister. The canister has an interior space defined by a wall surface and a first perforated baffle spaced apart from a second perforated baffle. The interior space contains a ferromagnetic matrix comprising split ring lock washers. The feed side end portion of the canister communicates with the wastewater source that contains the oily magnetic solids, a wash-water supply, a pressurized air supply and a disposal stream. The discharge side end portion of the canister communicates with a recycling stream, the disposal stream and the wash-water supply.

Abstract: A grey water recovery system comprises a filter tank having a filter medium therein. Grey water is delivered to the filter tank by a delivery conduit and filtered grey water is collected in a sump which surrounds the filter tank. A pump removes the filtrate to a distribution system for irrigation and similar use. The recovery system includes a backwash system. The backwash system has a flow responsive poppet valve which permits clean backwashing water and pressurized air to flow upwardly through the filter medium while closing the normal filtrate flow path to the sump.

Abstract: A control system for controlling a backwash operation in normal and high flow operating modes is provided in a traveling bridge filter having a filter basin; a filter media bed; a filtrate channel; a traveling bridge adapted to traverse the filter basin with a backwash hood suspended therefrom; a programmable logic controller; a reference sensor and five spaced water level sensors. The controller and the sensors control the backwash operation by sensor functions which differ between the normal and high flow operating modes.

Abstract: A filtration system having a volume of positively buoyant particulate material and a volume of negatively buoyant particulate material. The system includes a vessel having an upper port, a lower port and an intermediate drain port. As contaminated liquid travels between the upper and lower ports, it is filtered through both volumes of particulate material. The system may be operated with the liquid flowing in either direction between the upper and lower ports. To clean the system, the drain port is opened and cleaning liquid is pumped into the upper port and/or the lower port and flushed out the drain port. An alternate embodiment of the filtration system includes a vessel, two tubular members, a volume of positively buoyant particulate and a volume of negatively buoyant material. The two tubular members extend into the vessel and have slotted areas for travel of liquid into and out of the tubular members.

Abstract: An automatically-regulated, self-flushing method of filtering a liquid suspension includes passing the suspension through a granular filter material. The flow of suspension is halted to relieve the pressure in the system, so facilitating the settling of the removed particles down the filter. Further settling of the particles may be achieved by passing an airstream through the filter material. A reverse flow of the filtrate then effects a backwashing action on the filter material so that further settling of the particles is encouraged. The filter material may be contained in a drain passage which follows a generally sinuous path. The drain passage may serve a waste landfill site in which toxic, hazardous or domestic waste is disposed.

Abstract: An adapter valve for backwashing a water filter is releasably connected between the water filter housing cover and enclosure. The adapter valve includes a body having a source port for fluid communication with an inlet port of the cover, a storage port for fluid communication with an outlet port of the cover, a filter inlet port for fluid communication with an inlet port of the enclosure, a filter outlet port for fluid communication with an outlet port of the enclosure, a backwash port for fluid communication with a backwash tank, a discharge port for fluid communication with a discharge line and a cavity in fluid communication with the source, filter and discharge ports. A check valve is positioned between the filter outlet port and the storage port and between the backwash port and the storage port for permitting fluid flow to a storage tank during normal operation and for blocking fluid flow from the storage tank during backwash operation.

Abstract: A filtering process for and apparatus separating air bubbles and granular filter medium from a filtrate contaminated by the filter medium and bubbles when passing through a filter bed formed by the filter medium for treatment of a suspension or liquid solution, a gas being passed through the filter medium in contact therewith, includes providing a treated filtrate zone (3) above the filter bed (2), collecting the treated filtrate in the filtrate zone, conducting granular filter medium from the filter bed (2) upwardly through a conveying pipe (4) to a position above the filter bed and thereafter downwardly through a washing apparatus (5) from which the filter medium is precipitated onto a plate (11) above the filter bed.

Abstract: An apparatus and method for gas backwashing a granular media supported upon a lateral underdrain is disclosed. The lateral underdrain includes a plurality of dispersion apertures therethrough and at least one liquid return conduit extending to a discharge at a level below the dispersion apertures. The present invention provides for equal distribution of backwash gas across the entire lateral underdrain by directing backwash gas through the dispersion apertures into the granular media and directing liquid from the granular media through the liquid return conduit without obstructing backwash gas flow through said apertures from a gas pocket formed underneath said apertures.

Abstract: A treatment device such as a filter device, containing a treatment bed (2) of particulate treatment medium. A fluidizing unit (9) associated with the treatment medium particles, for removing the treatment medium particles from the treatment bed for rejuvenation. The fluidizing unit (9) comprises a liquid supply duct (11) having an outlet (10) and which is arranged to be fed with liquid under pressure from outside the filter bed, and a discharge duct (14) having an inlet (15) and which projects beyond the outlet (10) of the liquid supply duct.

Abstract: An apparatus for treating a fluid to remove at least part of a component or components from the fluid in a reciprocating flow ion exchange system. The apparatus includes a vessel having a central holding chamber that is enclosed at each end by an end cap. A packed bed of ion exchange particles is held within the central holding chamber through the use of upper and lower retaining means so that a particle free cavity is created above and below the particle bed. The flow of fluid is distributed substantially evenly across the end of the particle bed by the pressure drop through the bed when one of the particle free cavities is filled with pressurized fluid.

Abstract: Automatic backwash filter systems including a filter tank divided by vertical cell sheets into a multiplicity seriate cells are improved by provision, as retention for underdrain filter plates within the seriate cells, of unique contoured cell sheets having profiled faces each with a lower level, integral, protrusion segment that forms a support ledge for a cell filter plate and a higher level, integral, protrusion segment that provides a filter plate holddown feature in combination with filler members and horizontal retention bars.

Abstract: A device for separating contaminants out of the lube oil of an internal combustion engine is provided which includes a filter element, a centrifuge rotatable by means of the lube oil flowing through it, and at least one supply passage for lube oil to be cleaned and at least one drain passage for the cleaned oil. The filter element and the centrifuge are arranged in a common, closable housing with at least one of the filter element and the centrifuge being removable from the housing when the housing is open. The filter element and the centrifuge are arranged in the housing in vertical alignment and a single cover covers the common housing.

Abstract: An improved electro-coalescent/magnetic separation (ECMS) system for removing contaminants from water, including desalinization, comprises a device for exposing a stream of water to be treated to an electric field, followed by introduction of ionized coagulating substances, including ionized gases and/or metal ions, followed by plural filter stages. The first filter stage may comprise a polarizable glass, alumina, or ceramic media provided as a bed in a tank with an underdrain, so as to provide substantial residence time. A polishing filter may comprise a very fine fiber or organic gel filter element confined between relatively flexible electrically-conductive screen members and provided with a DC power supply to polarize the filter. This assembly is confined between relatively rigid, perforated members such that the filter assembly can move slightly upon backwash to dislodge caked-on contaminants or the like, while preserving the structural integrity of the filter assembly.

Abstract: A simplified single cell apparatus and method for removal of suspended impurities in liquids using gas flotation and filtration is provided wherein the method and apparatus are preferably directed to induced gas flotation separation of suspended impurities in combination with a filter media for filtration removal of remaining suspended impurities. A filter media is contained within the single cell apparatus such that liquid exiting the vessel must pass through the filter media after having been subjected to flotation treatment.

Abstract: A reactor for treating a liquid containing evolvable and entrained gas has a vessel for containing a bed of particulate media, and a liquid flow distributor mounted in the vessel that includes a manifold connected to receive liquid and introduce it into the bed. The manifold includes a liquid conveying passage having an upper region where any gas that evolves from the liquid can collect and at least one discharging nozzle having an inlet in open communication with the upper region for receiving the liquid, evolved gas or a mixture thereof, and an outlet for uniformly discharging the liquid, gas or mixture thereof into the bed.

Abstract: A cylindrical condensate filter housing is disclosed for the containment of a condensate filter media. The housing includes a domed, removable top member for the filter housing, and the domed top includes mounting means within its domed section for (1) a balanced pressure thermostatic air vent, (2) a backwash water inlet, (3) a filtered condensate outlet, and (4) a safety valve.

Abstract: A travelling bridge filtration unit includes a tank having a bottom wall, a pair of side walls and a pair of end walls arranged to provide a rectangular tank with an open top. An interior partition in the tank extends lengthwise between the pair of end walls forms a filtrate channel between the interior partition and one of the side walls, and a filter basin between the interior partition and the other of the pair of side walls, with a bed of filter media located in the filter basin. A travelling bridge is mounted on the tank for movement therealong in a lengthwise direction, the travelling bridge supporting a backwash pump and a backwash hood for movement across the filter basin in close proximity to the filter bed. A plurality of structural underdrain headers extend between the interior partition and the other of the pair of side walls, the headers having closed ends adjacent one of the side walls, and open ends extending through the interior partition in communication with the filtrate channel.

Abstract: Articulated sliding shoes for improving the operation of automatic backwashing filter systems basically include (a) a rectangular support frame, (b) a central valve member, (c) a fore waste valve member, (d) an aft waste valve member and (e) sets of springs for such valve members. The valve members are moveable relative to the support frame transverse of its longitudinal axis, but are immoble parallel to such axis and are urged by the spring sets into seriatim contact with trios of the discharge ports of the filter cells of such filter systems.

Abstract: A water filtering and purifying apparatus made according to the present invention comprises a water filtering and purifying apparatus for filtering and purifying water as it is ejected from a container at low gauge pressures generated by manually squeezing the container. The water filtering apparatus includes a cover for attaching to the container wherein the cover has a pressure responsive venting system for allowing air into the container while substantially preventing air and water contained in the container from escaping. A water filtration and purifying system is contained within the container and the filtration and purifying system comprises a replaceable pleated filter connected to a purifying cartridge.

Abstract: Apparatus (1) for treating a fluid, in this case wastewater, comprising a vessel or tank (2), a conduit (3) to supply the wastewater in an alternating sequence to the vessel (2), and a source (4) for oxygenating the bed of granular media (5) to provide aerated filter media. The filter bed is aerated during operation by air, oxygen enriched air or other gas being introduced at or adjacent the base (as viewed) of the bed through the source (4), which may be a perforated manifold, diffuser or the like extending substantially over the whole surface area of the bed (5). Also, the bed (5) is a granular media such as natural minerals or blast furnace slag media to the surface of the discrete particles of which is attached bacteria and microorganisms (a biomass) which effects treatment of the fluid.

Abstract: A simplified single cell apparatus and method for removal of suspended impurities in liquids using gas flotation and filtration is provided wherein the method and apparatus are preferably directed to induced gas flotation separation of suspended impurities in combination with a filter media for filtration removal of remaining suspended impurities. A filter media is contained within the single cell apparatus such that liquid exiting the vessel must pass through the filter media after having been subjected to flotation treatment.

Abstract: A filtering device for the clarification of liquids, such as industrial or waste waters, comprising an open tank provided with a floor possessing nozzles and supporting the filtering bed, side channels for arrival of the untreated water, a removal conduit for the filtered water, means for washing the material of the filter and an axial channel for removal of the washing waters, wherein the bottom of the filter, below the floor, is separated along its longitudinal axis by a watertight partition defining two independent cells in the filter.

Abstract: An apparatus and method of using the apparatus in the final stages of purification of sewage water in which the effluent is placed under pressure by a pump and forced through a filter. Part of the effluent is sampled and chlorinated by a chlorine gas injector and then reintroduced into the lager body of effluent. The entire mixture is held within a detention chamber in order to allow the chlorine to dissipate, and then pumped out into a natural stream through a pipe in which air bubbles are injected in order to replenish the oxygen level.

Abstract: An apparatus and method for gas backwashing a granular media supported upon a lateral underdrain is disclosed. The lateral underdrain includes a plurality of dispersion apertures therethrough and at least one liquid return conduit extending to a discharge at a level below the dispersion apertures. The present invention provides for equal distribution of backwash gas across the entire lateral underdrain by directing backwash gas through the dispersion apertures into the granular media and directing liquid from the granular media through the liquid return conduit without obstructing backwash gas flow through said apertures from a gas pocket formed underneath said apertures.

Abstract: A method of cleaning a filtration tank having a plurality of side-by-side gravity flow filter cells, each having an outlet port in communication with a filtrate channel common to all of the cells in an automatic backwash/rewash system, by subjecting each compartment, sequentially, to a backwashing operation and then a rewashing operation wherein, during backwashing, backwash liquid is pumped through a first of the filter chamber ports to flow upwardly through a first of the compartments in a direction opposite to a normal filtration flow direction, and during rewashing, rewash liquid is drawn downwardly through the first cell in the normal filtration flow direction. For any given cell after a first of the plurality of cells, utilizing at least a portion of the rewash liquid from a rearwardly adjacent filter cell is used as backwash liquid in the given cell.

Abstract: A waste water treatment system is illustrated which can be configured to be portable and which minimizes the addition of solids to be disposed of through the use of ozone for contaminant reduction to basic elements after the pH value of the waste water to be treated is properly adjusted. This ozone in one stage is combined with ultrasound to cause coagulation and precipitation. In another stage, ozone and ultraviolet light are used in a reduction process. Ion alignment using a magnetic field and an electrochemical flocculation process to which the waste water is subjected causes further coagulation and precipitation. As designed, the system can operate continuously with redundancy at appropriate points so that removal of solids from the filtration units can occur simultaneous with the overall decontamination process.

Abstract: A rapid gravity downflow filtration system applicable to a bank of several filters in which filtered water for backwashing is stored at a relatively high level in a common washwater storage compartment serving all filters and in which the filtered water for backwashing is delivered to it's storage by gravity using the surplus operating head available at the beginning of the filter operating cycle for the purpose thereby entirely eliminating the necessity for powered motivation of backwash water flow during backwashing, or, in alternative filter systems in which the backwash water flow is motivated by displacement with compressed air, reducing the power requirement.

Abstract: A filter underdrain module for an underdrain system for a granular media filter. The module is an elongated, integrally constructed, self-contained unit having an enclosed interior and having a substantially flat, substantially rectangular exterior top wall. The water and air for simultaneous backwashing and scouring the filter media are separately conveyed by conduits within the module, and separately discharged into the filter support bed or directly into the filter media, as the case may be. The discharge openings for the water and air are located in the top exterior wall of the module. The discharge openings for water are all substantially the same shape and size, and substantially uniformly spaced along the length and breadth of the module. The same is preferably true of the air discharge openings. Various preferred embodiments are disclosed, including dual ducts for one or both of the separate conduits for cleaning water and scouring air. An underdrain system using the module is disclosed.

Abstract: A filter for removal of biochemical oxygen demand and suspended solids utilizing multi-layer filtration media. The filter media includes plastic particles, sand, and garnet and is operated under an automatic control condition. Fine filtering is accomplished by a sludge cake which develops at the upstream face of the filter media. For cleaning the filtration media, deposited sludge is removed from the filter bed by backwashing in a short time period at a high strength backwash flow rate.

Abstract: A traveling bridge filtration system includes a tank configured to include a plurality of side-by-side filter cells all extending longitudinally in a first direction, and a common filtrate channel extending longitudinally in a second direction perpendicular to the first direction. Each filter cell has an outlet extending through an interior wall of the tank thereby establishing fluid communication with the filtrate channel. A traveling bridge is mounted atop the tank and movable from cell to cell in the second direction. A backwash pump, having an inlet and a discharge pipe connected to a backwash shoe, is pivotally suspended from the bridge within the filtrate channel. A fluid operated bellows is used for moving the backwash shoe selectively into sealing engagement with a tank wall surface surrounding one of the filter cell outlets in response to actuation of the backwash pump. A related method of use is also disclosed.