Abstract: A filtration system that includes a plurality of underdrain blocks arranged to define a plurality of laterals. Each underdrain block defines an interior and an exterior and has an orifice that provides fluid communication between the exterior and the interior. The system also includes a plurality of media retaining plates. Each plate includes a plurality of slots that extend through the plate. Each slot has an average width of less than 0.065 inches. Each plate connects to only one of the plurality of underdrain blocks such that the slots provide fluid communication between the exterior and the orifice of the underdrain block to which the plate is attached.

Abstract: A filtration device that enables efficient cleansing and rinsing of filtration media within a short time, in which filtration sand is not likely to become clogged, and in which unevenness within filtration sand is not likely to occur comprising a screw conveyor 32 provided within a cleansing tank 38, which is suspended from the upper portion of a filtration tank 2, a space 52 being formed between a filter bed 4 and a wire mesh 50, which are vertically separated, filtration media 14 provided on the wire mesh 50, and filtration media 54, having larger particle sizes than the filtration media 14, provided within the space 52 and a plurality of strainers 12 provided in the filter bed 4 and cleansing water spraying pipes 58 provided on an outer wall surrounding the space 52 and after the screw conveyor 32 is rotated and the filtration media 14 has been cleansed, cleansing water is sprayed from a filtered water discharge pipe 46 and the cleansing water spraying pipes 58, to expel contaminants through a raw water su

Abstract: An underdrain block for a filter system comprises a housing that has of a top wall, a bottom wall, a first end wall, a second end wall, a first side wall, and a second side wall. The end walls and the side walls connect the top wall to the bottom wall. The bottom wall forms two lateral rows of support legs configured to straddle infrastructure of the filter system. One or more snap-locking mechanisms are located on the side walls so that adjacent underdrain blocks are interconnected by the locking mechanisms when snapped in place. In one embodiment, the first side wall comprises one or more tongue lugs and the second side wall comprises one or more groove lugs, each groove lug defines a groove for mating with the tongue lug so that adjacent housings are interconnected by the tongue-in-groove locking mechanisms when the tongue lugs are snapped into the grooves.

Abstract: A filter underdrain system and a method for measuring the water flow through the underdrain filter system. The apparatus includes panel members assembled to form a perforate grid on the filter base structure of an underdrain block. The panels are generally rectangular and have an upper and lower surface. Multiple apertures are provided in the panel member. The number and/or size of the apertures are dimensioned to prevent the egress of filter media and to obtain substantially uniform backwash flow in the underdrain thereby reducing or eliminating water maldistribution.

Abstract: The invention is directed to a filter underdrain for supporting a filter media between at least two dividers forming at least one cell, which includes at least one porous plate for supporting the filter media for filtering a fluid, the porous plate spanning across at least one of the dividers; and a plurality of support members beneath the porous plate, the support members containing at least one port for draining the fluid after the fluid passes through the porous plate. The porous plates may be bound together by a lap joint and an end section may be included between at least two of the support members, the end section containing at least one pocket for holding the porous plate.

Abstract: A lid for an underdrain block that has a top surface defining an opening for receiving fill material. The top surface forms a ridge circumscribing the opening, the lid comprising a top, a bottom and a peripheral edge, the peripheral edge comprising a rim adapted to interlock with the ridge. The ridge of the underdrain block can have a flange perpendicular to the top surface and the rim on the lid is adapted to tightly fit over the flange so that the rim interlocks with the flange. Alternatively, the underdrain block for a filter system comprises a hollow plastic housing comprising a top wall that defines an opening for receiving the fill material. The top wall forms a ridge surrounding the opening and the lid seals the opening in the top wall. The lid comprises a peripheral edge that forms a u-shaped rim. The u-shaped rim has a locking means to tightly fit over the ridge so that the rim interlocks with the ridge so as to seal the opening.

Abstract: The invention recites a filtration tank including a chamber for holding liquid to be filtered, the filtration tank includes a fluid inlet for providing liquid to the chamber. The filtration tank further includes a fluid outlet and at least one filter block disposed between the inlet and the outlet, wherein the at least one filter block includes a porous cap having an average pore size of up to about 250 microns.

Abstract: A filter system employing a modular filter and at least one high rate pre-treatment system for expeditiously and effectively filtering water. The modular filter includes a reservoir housing for containing fluid. A plurality of filter cells are disposed in the reservoir housing for filtering influent passed through the reservoir housing. Each of the plurality of filter cells has at least one layer of media. A moveable backwash assembly is provided for sequentially backwashing the plurality of filter cells. The backwashing procedure is performed on the modular filter system such that while one of the plurality of cells is being backwashed the remaining cells are filtering pre-treated influent processed by the pre-treatment system. The pre-treatment system preferably has a footprint considerably smaller than the footprint of the modular filter.

Abstract: An underdrain system having a bottom formed of concrete. The concrete bottom includes a plurality of depressions formed therein. A porous plate is operably associated with at least one of the depressions. An anchor assembly is provided for anchoring the porous plate to the concrete bottom in an efficient and cost effective manner. Preferably, the anchor assembly permits the porous plate to be readily replaced. An optional insert may be used to enhance the distribution of the flow of fluid through the porous plate.

Abstract: The invention recites a filtration system including a block including a first wall and a second wall substantially parallel to the first wall. A top surface that is substantially perpendicular to the first wall is disposed between, and coupled to, the first and second walls to at least partially define an inner chamber. The top surface further includes an orifice defining a passageway between a block exterior and the inner chamber. A plate including a plurality of slots, each slot having a width of less than about 0.065 inches, and a slot outlet, is coupled to the top surface of the block. The slot outlets in the plate are substantially coplanar and the plate, when coupled to the block, substantially covers the orifice.

Abstract: A fluid distribution system for directing fluids through a filter system. The fluid distribution system ensures proper distribution of fluids during the process of filtering as well as the process of washing a filter bed. The fluid distribution system may be used with numerous filter systems including but not limited to an upflow filter, a downflow filter, a combined upflow/downflow filter and/or multiple downflow filters connected in series.

Abstract: An underdrain system having a bottom formed of concrete. The concrete bottom includes a plurality of generally cone shaped depressions formed therein. A porous plate is operably associated with at least one of the generally cone shaped depressions. The underdrain system further includes an insert having at least one distribution orifice for distributing the flow. The insert is positioned beneath the porous plate and at least partially within the at least one generally cone shaped depression. The insert insures thorough distribution of any fluid passing through the porous plate, i.e., the fluid is evenly distributed over the entire surface area of the porous plate. In an alternative embodiment, an underdrain system is provided including a bottom formed of concrete. The bottom has a plurality of generally cone shaped depressions formed therein. A porous plate is operably associated with at least one of the generally cone shaped depressions.

Abstract: The invention is directed to an automatic backwash filter system that includes at least one influent port for introducing a fluid to the filter; a plurality of partitions forming a plurality of compartments for holding a filtering media for filtering the fluid; at least one porous plate for supporting the plurality of partitions; wherein each of the partitions is mounted atop a continuous portion of the porous plate; and at least one effluent port for draining the fluid away from the compartments. The filter may also include a filter media comprising one or more selected from the group consisting of sand, anthracite coal, and activated carbon.

Abstract: The present invention relates to the raw water-filtering technical field, and is to provide a high speed filtering apparatus which can filter a great amount of raw water containing suspended substances (SS) at a high concentration at a high speed. Floating filter media 2, which are composed of a foamed polymer having an apparent density of 0.1 to 0.4 g/cm3 and a 50% compression hardness of not less than 0.1 MPa and have uneven shapes or cylindrical shapes with sizes of 4 to 10 mm, are charged into an up-flow type filtering tower 1. The raw water containing SS at a high concentration is filtered by passing it through the filtering tower 1 at a linear water-passing speed of 100 to 1000 m/day. While the floating filter media 2 are not compacted, a high SS-capturing percentage can be obtained. Back washing can be also effected at a high linear washing speed of 1.2 to 4.0 m/min.

Abstract: The invention recites a filter comprising a block including an outer wall defining an inner chamber and a block exterior, and a conduit having a conduit wall, a first conduit end, a second conduit end, and an inner flow path providing fluid communication between the first and second conduit ends. The conduit wall includes an orifice therethrough. The conduit is coupled to the block such that the first conduit end is in fluid communication with the inner chamber of the block and the second conduit end and the orifice are in fluid communication with the block exterior.

Abstract: A filter underdrain apparatus and a method for manufacturing such apparatus. The apparatus includes a cover member, a water orifice member and a bottom member, each being individual pieces. The cover is placed over the water orifice member and connected thereto by welding. The bottom member is likewise connected to the cover and water orifice members by welding. A water passageway and an air passageway are defined in the inside of the assembled members. Water egress from the water passageway is provided by holes in the water orifice member and the cover. Air egress from the air passageway is provided by holes in the cover.

Abstract: A media bed support grid for use with a vessel having an inner surface. The media bed support grid comprises a plurality of filter panels, each filter panel having a plurality of parallel and spaced-apart filter wires, the plurality of filter wires forming a filtering surface. The media bed support grid also comprises a plurality of channels underlying and positioned substantially perpendicular to the filter wires. The media bed support grid further comprises a plurality of manifolds, each manifold being coupled to and in fluid communication with the channels.

Abstract: A filtration apparatus includes a tank having an upper chamber and a lower baffle, layers of stone and carbon between the upper chamber and the lower baffle, a water inlet to the upper chamber, and a water outlet below the lower baffle. The upper chamber is divided by a vertical baffle which separates the water inlet from a backwash outlet. A backwash inlet is provided below the lower baffle. An air manifold coupled to an air pump is placed between the lower baffle and the upper chamber. During backwash, air is mixed with water to cause a turbulent flow. The baffle in the upper chamber prevents filter media from exiting the apparatus during backwash.

Abstract: An improved underdrain block for an underdrain system supporting a filter media bed in a liquid filtration system is provided. The underdrain blocks are preferably made of an extrudable polymeric material that is extruded in relatively long sections to provide light weight, strong, easily manufactured underdrain systems having a lower profile than prior art underdrain blocks. The underdrain block comprises an upper wall, side walls, a lower wall, at least one lateral member between the upper wall and the lower wall, at least two chambers within the underdrain block, each chamber being defined by the lateral member, a plurality of upper orifices in the upper wall of the underdrain block, and a plurality of internal orifices in the lateral member. The underdrain block is substantially greater in longitudinal length than a longitudinal distance between the upper orifices.

Abstract: A porous media support plate module may be used to construct a new filter underdrain or to rehabilitate an existing filter underdrain. A porous plate replacement module may be inserted between two existing cell dividers to replace a damaged porous media support plate, which may be allowing media leakage. The design of the replacement module provides an improved plenum structure, which enhances the backwash process and reduces the drawbacks of applying adhesives in varying weather conditions. In an alternative design, a module may be provided to enhance the backwash process of existing cells.

Abstract: The invention is directed to a filter underdrain for supporting a filter media between at least two dividers forming at least one cell, which includes at least one porous plate for supporting the filter media for filtering a fluid, the porous plate spanning across at least one of the dividers; and a plurality of support members beneath the porous plate, the support members containing at least one port for draining the fluid after the fluid passes through the porous plate. The porous plates may be bound together by a lap joint and an end section may be included between at least two of the support members, the end section containing at least one pocket for holding the porous plate.

Abstract: An underdrain system having a bottom formed of concrete. The concrete bottom includes a plurality of depressions formed therein. A porous plate is operably associated with at least one of the depressions. An anchor assembly is provided for anchoring the porous plate to the concrete bottom in an efficient and cost effective manner. Preferably, the anchor assembly permits the porous plate to be readily replaced. An optional insert may be used to enhance the distribution of the flow of fluid through the porous plate.

Abstract: The invention recites a filter comprising a block including an outer wall defining an inner chamber and a block exterior, and a conduit having a conduit wall, a first conduit end, a second conduit end, and an inner flow path providing fluid communication between the first and second conduit ends. The conduit wall includes an orifice therethrough. The conduit is coupled to the block such that the first conduit end is in fluid communication with the inner chamber of the block and the second conduit end and the orifice are in fluid communication with the block exterior.

Abstract: The invention recites a filtration system including a block including a first wall and a second wall substantially parallel to the first wall. A top surface that is substantially perpendicular to the first wall is disposed between, and coupled to, the first and second walls to at least partially define an inner chamber. The top surface further includes an orifice defining a passageway between a block exterior and the inner chamber. A plate including a plurality of slots, each slot having a width of less than about 0.065 inches, and a slot outlet, is coupled to the top surface of the block. The slot outlets in the plate are substantially coplanar and the plate, when coupled to the block, substantially covers the orifice.

Abstract: The invention is directed to an automatic backwash filter system that includes at least one influent port for introducing a fluid to the filter; a plurality of partitions forming a plurality of compartments for holding a filtering media for filtering the fluid; at least one porous plate for supporting the plurality of partitions; wherein each of the partitions is mounted atop a continuous portion of the porous plate; and at least one effluent port for draining the fluid away from the compartments. The filter may also include a filter media comprising one or more selected from the group consisting of sand, anthracite coal, and activated carbon.

Abstract: A wastewater treatment unit (10) including a recirculation chamber (32), a dosing chamber (34) having no direct fluid connection to the recirculation chamber (32), and at least two filter layers (28, 30) in a single tank (12). Each filter layer (28, 30) containing filter media (56) and being located above the recirculation (32) and dosing chambers (34). The wastewater treatment unit (10) also including an influent pipe (50), a recirculation pump (72) located in the recirculation chamber (32), and an effluent discharge pipe (88) connected to the dosing chamber (34).

Abstract: An apparatus for retrofitting a water filtration underdrain and a method therefor are provided. The apparatus comprises a nozzle for uniform water distribution through the filtration media, a conduit to provide fluid flow communication between the nozzle and an opening in the underdrain, and a filler substance configured to fill depressions of the type generally found in Bell bottom and Wheeler underdrain systems. Alternatively, the apparatus may comprise a nozzle and a pre-molded insert formed to mate with the depression including a channel to provide fluid flow communication between the nozzle and an opening in the underdrain. Methods for retrofitting a water filtration underdrain system using such devices are also provided.

Abstract: An apparatus provides for treatment of primary effluent from residential and commercial establishments to allow subsurface or surface disposable of wastewater.

Abstract: An underdrain filtration system has improved perforation structure, the perforations being positioned to admit the filtrate into a plenum defined by elongated underdrain rib structures of the system. Instead of drilled or laser-cut holes or slits, the slits are formed by stamping discs from the stainless steel plate, such that the discs extend parallel to the surrounding flat area but are raised just sufficiently to define a plurality of slits under each disc, preferably two to four slits, each being an arc of slightly less than 180°, 120° or 90°, respectively. A pair of metal bridges remain to integrally connect the raised disc and the surrounding flat field. Consistent perforation width is achieved, at, for example, 0.010″ width varying by less than 0.001″ in either direction, improving consistency of pressure drop.

Abstract: A fluid distribution system for directing fluids through a filter system. The fluid distribution system ensures proper distribution of fluids during the process of filtering as well as the process of washing a filter bed. The fluid distribution system may be used with numerous filter systems including but not limited to an upflow filter, a downflow filter, a combined upflow/downflow filter and/or multiple downflow filters connected in series.

Abstract: A gravity-assisted water saving system, and a method for its use, that can be utilized to collect the condensate from an air conditioning system, sanitize it, and then divert it for constructive use. It has a chamber with an inclined bottom surface, a dimension slightly larger than a stack of several tablets used for sanitizing swimming pool water or bleach tablets used for laundry sanitizing purposes, a P-trap on its water inlet side that prevents corrosive fumes from entering the air conditioning system from which the condensate is derived, a removable cap sealing its top opening to prevent escape of corrosive fumes into the atmosphere, and an optional mounting bracket for enhanced stabilization. Inflow tubing connected to the chamber permits ready attachment of the present invention to an air conditioning condensate discharge pipe, while a discharge tube in an inferior position transports reclaimed water to its location of subsequent use.

Abstract: An underdrain system having a bottom formed of concrete. The concrete bottom includes a plurality of generally cone shaped depressions formed therein. A porous plate is operably associated with at least one of the generally cone shaped depressions. The underdrain system further includes an insert having at least one distribution orifice for distributing the flow. The insert is positioned beneath the porous plate and at least partially within the at least one generally cone shaped depression. The insert insures thorough distribution of any fluid passing through the porous plate, i.e., the fluid is evenly distributed over the entire surface area of the porous plate. In an alternative embodiment, an underdrain system is provided including a bottom formed of concrete. The bottom has a plurality of generally cone shaped depressions formed therein. A porous plate is operably associated with at least one of the generally cone shaped depressions.

Abstract: An improved underdrain block for an underdrain system supporting a filter media bed in a liquid filtration system is provided. The underdrain blocks are preferably made of an extrudable polymeric material that is extruded in relatively long sections to provide light weight, strong, easily manufactured underdrain systems having a lower profile than prior art underdrain blocks. The underdrain block comprises an upper wall, side walls, a lower wall, at least one lateral member between the upper wall and the lower wall, at least two chambers within the underdrain block, each chamber being defined by the lateral member, a plurality of upper orifices in the upper wall of the underdrain block, and a plurality of internal orifices in the lateral member. The underdrain block is substantially greater in longitudinal length than a longitudinal distance between the upper orifices.

Abstract: A rain water run-off filtering system includes a tank for holding and filtering run-off water, said tank being generally cylindrical with a horizontal axis, and having at least one manway for the introduction of water and a filter media. A horizontal grate disposed at the bottom of the tank, supports a bed of gravel and sand, and incoming water is directed onto the sand bed, thence percolating through the sand to a space below the grate. The outflow of water from the tank is regulated by a baffle plate bounding the sand bed. This plate has small holes for normally producing a small outflow, and at least one large aperture for permitting water to flow through the tank, without percolating through the sand, during extremely heavy rains.

Abstract: Clarifier for liquids laden with suspended matter, comprising: an outer, first, cylindrical tank (4), a central, second, cylindrical tank (1) for collecting the filtered liquid, roughly coaxial with the first; an intermediate tank (2), formed between the outer tank (4) and the central tank (1) and roughly coaxial therewith; structure (19) for the feed of pressurized backwash liquid to the filter medium (14); a hood (26) for recovering the washing liquid after it has passed through the filter medium (14); a rotary bridge (8) which can rotate above the collection of cylindrical tanks (1, 2, 4), a compartment for introducing the liquid that is to be clarified, this compartment being positioned between the intermediate tank (2) and the central tank (1) and feeding the outer tank (4) centrally with liquid laden with suspended matter, the said compartment being itself fed with liquid that is to be clarified from the outside via a number of inlets (3).

Abstract: A concurrent backwash distribution apparatus for a filter having a filter tank and a plurality of underdrain laterals includes a baffle positioned in a common main conduit to define an auxiliary flume between the baffle and the underdrain laterals. The auxiliary flume is in fluid communication with the common main conduit and the underdrain laterals. The baffle has at least one flume liquid metering orifice preferably located near the bottom of the baffle so that it may be below a gas/liquid interface in the auxiliary flume during concurrent gas/liquid backwash operations. A flow distribution plate may be positioned between the auxiliary flume and the underdrain laterals, the flow distribution plate having at least one liquid metering orifice and at least one gas metering orifice. The baffle may take one of many forms. The baffle creates an adequate liquid pool in the common main conduit for low velocity flow of backwash liquid while at the same time providing uninhibited flow of backwash gas.

Abstract: A filter media support system that reduces media clogging and head loss in granular filtration systems by providing a layered porous plate. The porous plate can have multiple layers of fine sized and coarse sized pores. The porous plate is positioned between the media and the filter bottom. The filter media support system is securely anchored to the infrastructure of the underdrain system thereby inhibiting media penetration of the filter bottom and avoiding seal failures. The infrastructure can be air lateral piping fitted beneath the underdrain blocks of the support system. The anchors can be secured to pipe clamps circumscribing the air laterals.

Abstract: A concurrent backwash distribution apparatus for a filter having a filter tank and a plurality of underdrain laterals includes a baffle positioned in a common main conduit to define an auxiliary flume between the baffle and the underdrain laterals. The auxiliary flume is in fluid communication with the common main conduit and the underdrain laterals. The baffle has at least one flume liquid metering orifice preferably located near the bottom of the baffle so that it may be below a gas/liquid interface in the auxiliary flume during concurrent gas/liquid backwash operations. A flow distribution plate may be positioned between the auxiliary flume and the underdrain laterals, the flow distribution plate having at least one liquid metering orifice and at least one gas metering orifice. The baffle may take one of many forms. The baffle creates an adequate liquid pool in the common main conduit for low velocity flow of backwash liquid while at the same time providing uninhibited flow of backwash gas.

Abstract: A filter media support system that reduces media clogging and head loss in granular filtration systems by providing a layered porous plate. The porous plate can have multiple layers of fine sized and coarse sized pores. The porous plate is positioned between the media and the filter bottom. The filter media support system is securely anchored to the infrastructure of the underdrain system thereby inhibiting media penetration of the filter bottom and avoiding seal failures. The infrastructure can be air lateral piping fitted beneath the underdrain blocks of the support system. The anchors can be secured to pipe clamps circumscribing the air laterals.

Abstract: A method for retrofitting a gravity filter with a porous plate filter media support that increase filter production by increasing the depth of the media, allows installation of an air backwash system in filters having a monolithic underdrain system, and reduces turbulence and head loss in granular filtration systems. The method comprising removal of existing media and gravel media-support bed and installation of a porous plate media support. The porous plate can have multiple layers of fine sized and coarse sized pores. The porous plate is positioned between the media and the filter bottom and is securely anchored to the monolithic underdrain system thereby allowing uniform distribution of backwash, inhibiting media penetration of the filter bottom and avoiding seal failures.

Abstract: A septic system filter apparatus for filtering waste water as it travels from a septic tank to a septic field. The septic system filter apparatus includes a filtering system for filtering water from a septic tank for receiving waste material. A filtering apparatus comprises a first housing having a bottom wall and a top wall. The top wall is a removable lid. The first housing has a first inlet port and an exit port. The bottom wall has at least two supports thereon extending upward from an inner surface of the bottom wall. A second housing for holding filtering material has a removable lid thereon. The second housing has dimensions smaller than the first housing to fit into the first housing. A space is defined between the first housing and the second housing. The second housing rests on the supports above the inner surface of the bottom wall. The second housing has a second inlet port located generally adjacent to the first inlet port. The second housing has an upper chamber and lower chamber.

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 wastewater treatment unit (10) includes a recirculation chamber (32), a dosing chamber (34) having no direct fluid connection to the recirculation chamber, and at least two filter layers (28,30) in a single tank (12). Each filter layer contains filter media (56) and is located atop the recirculation and dosing chambers. The wastewater treatment unit also includes an influent pipe (50) connected to the recirculation chamber, a recirculation pump (72), a recirculation valve (74), and an effluent discharge pipe (88) connected to the dosing chamber. In operation, the influent pipe directs wastewater entering the unit into the recirculation chamber. The recirculation pump feeds wastewater from the recirculation chamber onto the filter layers. The recirculation valve then directs the filtrate back to the recirculation and dosing chambers. The filtrate is then discharged from the unit via the effluent discharge pipe.

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: 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: 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: In a fluidized bed filtering apparatus, for preventing particles of filtering material from entering into a feed pipe to clog the feed pipe and lowering the frequency of washing operations, a filtering material layer made of granular filtering material is supported by a supporting layer disposed in a filtering chamber so as to provide a space in the lower portion of the filtering chamber and two lines of a first feed pipe the outlet of which opens in the filtering material layer and a second feed pipe the outlet of which opens within the space are provided for feeding corrupt water into the filtering chamber.

Abstract: A filter bed base for the treatment of wastewater discharged from a dwelling, business or like producer. The filter bed base is generally rectangular in shape and includes an upper and lower surface. The upper surface of the filter bed base has a plurality of orifices for distributing filtered effluent into various chambers inside the base. The lower surface of the base has a plurality of orifices which are positioned beneath a select number of the chambers for discharging a portion of the filtered effluent into the soil underlying the base.

Abstract: The present invention is directed to an aquarium undergravel filter. In particular, the undergravel filter of the present invention contains chambers on its underside. The chambers, which are roughly equal in size, are separated by baffles and have openings which allow water to flow into flow channels which lead to the lift tube holes. The chambers and flow channels provide for equal filtration over the entire surface of the filter plate. In a preferred embodiment, the undergravel filter of the present invention also contains an anti-dig grid which prevents fish from digging the gravel on the plate of the filter by use of an anti-dig grid. The anti-dig grid is located on the top surface of the filter and prevents fish from removing the gravel and exposing the openings in the filter.

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.