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: The invention relates to a method for regulation of aeration in a biological filter of the type comprising conveyance means (3) bringing water to be filtered into the lower part of the filter, a filter bed (2) acting as a support to the biomass, means of distributing an oxygenated gas (5, 5a) in the filter bed (2), a layer of filtered water (7) above the said filter bed, a nozzle for (4) of discharging the filtered water in the upper part of the filter, characterized in that it consists of taking account of the efficiency Ct with which the biomass uses the distributed oxygen to regulate the said distributed oxygenated gas flow and/or its concentration in molecular oxygen, in order to optimize the quantity of molecular oxygen distributed by the said distribution means.

Abstract: A method for the treatment of a liquid in a reactor comprising a chamber having an upper portion and a lower portion, a liquid inlet located in the upper portion of the chamber, a liquid outlet located in the lower portion of the chamber and an absorbent bed within the chamber between the upper and lower portions thereof, said method comprising using as said absorbent bed a porous packing that is able to absorb by capillarity the liquid to be treated, said porous packing having a given capillarity height h.sub.s which is the height that the liquid to be treated reaches by capillarity action when it is fed in a column filled up with a continuous layer of said porous packing; mounting at least one horizontally extending separation member within the chamber so as to divide the absorbent bed into at least two superimposed layers of a given height that is equal to or lower than h.sub.

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: The method of reducing the acidity in effluent discharges comprises charging the effluent with carbon dioxide, intermittently fluidizing and expanding at least one pulsed limestone bed with the charged effluent, treating the charged effluent with the limestone in the bed, displacing the limestone treated effluent with untreated charged effluent, stripping excess carbon dioxide from the effluent after treatment in the limestone bed, and discharging the limestone treated effluent.

Abstract: A method and apparatus for the biochemical purification of a contaminated liquid medium, in which the liquid medium is passed through granular filter material provided in a holder and in which the granular filter material (12) contained in the holder is set in motion, preferably with the aid of an injected gas such as air. Microorganisms and/or an active water for microorganisms can be added to the holder. The filter material may comprise a mixture of lava and sand, for example 28% to 38% sand and 61% to 71% lava. The granule size of the sand is 0.3 to 1.2 mm and the granule size of the lava is 2 to 10 mm. The main flow of the medium to be purified and the injected gas are oppositely directed. To set the filter material in motion, use is made of an inner tube (33) placed in an outer tube (32), gas being blown through the inner tube under the lower end of the inner tube (31) so that gas and filter material drawn in at the lower end of the tubes and medium are transported upward through the inner tube.

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 separator for use with a fluidized-bed bioreactor. A lift draws a slurry of liquid, media and biomass from the fluidized bed. A biomass discharge is connected to the lift and located above the height of the fluidized bed for discharging excess biomass. A media discharge, also connected to the lift, discharges media from the slurry and returns the media to the fluidized bed.

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: The present invention provides a floating media bioclarifier having an economical structure which allows energy efficient and water conserving backwashing of the floating media. The bioclarifier includes a filter chamber fluidly connected to a charge chamber which is adapted for accumulating air. A trigger device positioned between the charge chamber and filter chamber selectively allows the flow of air from said charge chamber to said filter chamber. An air source is connected to the charge chamber and slowly supplies air thereto. The backwash cycle is initiated by the trigger device allowing air to escape from the charge chamber into the filter chamber and adgitate the floating media. Simaltaneously, water from the filter chamber flows into the charge chamber. After the trigger device closes, air agains accumulate in charge chamber in preparation for another backwash cycle.

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: In the biological purification of sewage water or drinking water, it is known to purify the water in a filter bed of granular filter medium, wherein the filter medium is transported from the bottom of the bed to its upper side with the aid of air, so as to obtain a continuously working filter. It is suggested in accordance with the invention that the amount of filter medium to be transported is divided into two or more parts which are transported in parallel, so as to prevent the flow conditions in the transport tube having a negative effect on the reactivity of the filter bed by decreasing the bacteria strain.

Abstract: A structure for the absorption or desorption of a substance on a bed through which liquid is allowed to pass comprises a vessel containing a liquid-permeable bed, a lower adaptor, an upper adaptor and means for providing a liquid flow to the bed through one of the adaptors and means for conducting a liquid flow away from the bed through the other adaptor. The lower adaptor is arranged in the lower part of the vessel and at least partially defines the vessel bottom. The lower adaptor has an opening for the passage of liquid to or from the lower part of the vessel, which opening is directed toward the bed, and the lower adaptor is provided with a distribution facility for distributing or collecting liquid flow towards or from, respectively, a bottom surface of the bed. The upper adaptor is arranged in an upper part of the vessel and at least partially covers a cross-sectional area of the vessel.

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 suspension is delivered to a filter bed comprised of granular filter medium in a continuously working filter at the lower part of the bed and is then permitted to flow upwards through the bed. With the intention of optimizing the capacity of the filter, the suspension is now guided into a central region of the bed. The suspension is divided from this region into at least two specific proportional quantities which are each led from the filter bed in a respective ring-shaped pattern at mutually different heights in relation to the extension of the bed, these ring-shaped patterns having different diameters and each being adapted to the extension of the filter medium in the direction of the diameter.

Abstract: In a method for backwashing a water processing system using a buoyant filter layer constrained under wire mesh screen extending across a processing vessel, a water surface level in the processing vessel is lowered below the wire mesh screen. Air is subsequently released from under the buoyant filter layer to separate substances clogging the filter layer, while allowing the release of air out of said vessel from an upper part thereof. By lowering the water surface level below the upper wire mesh screen, the filter material is allowed to move more freely because the filter material is not restricted by the wire mesh screen from making upward movement. Hence, when air is released from under the filter layer, the filter material can move uniformly over the entire filter layer, and the clogging substances such as SS captured by the filter material and the biological film formed on the surface of the filter material can be favorably removed without damaging the filter material.

Abstract: A separator is provided for use with a fluidized-bed bioreactor. A lift draws a slurry of liquid, media and biomass from the fluidized bed. A biomass discharge is connected to the lift for discharging excess biomass. A media discharge, also connected to the lift, discharges media from the slurry and returns the media to the fluidized bed by means of a media return assembly.

Abstract: A continuous sand filter has a tank provided therein with a first separation container and a second separation container. The continuous filtration of the waste water is carried out in the first separation container and the second separation container. The first separation container is provided with an arresting piece capable of enhancing the filtration effect. The light and the heavy impurities are treated separately in the first separation container. The further filtration process is carried out continuously in the second separation container.

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: A water treating apparatus is provided which can treat waste water for use as raw water in an ultrapure water producing system without addition of various kinds of chemicals. The apparatus includes a first water tank for receiving acid waste water, a second water tank for subjecting the waste water from the first water tank to solid-liquid separation and discharging supernatant liquid, an ion exchange tank including ion exchange resin and an aeration tube for generating treated water through a membrane filter, a precipitation tank for settling ion exchange resin, an air lift pump for introducing ion exchange resin from the precipitation tank into the first water tank, and a return air lift pump for returning ion exchange resin from the second water tank to the ion exchange tank. The ion exchange resin acts to exchange ions with fluorine ions of treated water in the ion exchange tank and is regenerated by acid waste water in the first water tank.

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: Air grid systems for distributing a gas within treatment systems such as underdrain filters and contact clarifiers is disclosed. The air grid is supported from above so that it can be lowered into position and thus modified or repaired. Additionally, this feature permits retrofitting an air grid into an existing system, such as an underdrain filter, in which the bed of media overlies the underdrain is not upset by the installation. Thus, methods of installing or retrofitting air grid systems are also disclosed. In another aspect of the present invention, the air grid is comprised of an air manifold connected to air laterals by a spreader conduit that is inserted through a smooth bore in the walls of the manifold, thereby providing a simple and easy to manufacture structure that avoids problems found in prior art components.

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: 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: An improved vertical filtration unit includes a bell-shaped lower end for the air-lift tube, an injection ring for introducing air into the air-lift tube at a considerable volume, and a washbox with a more efficient scrubbing arrangement for washing dirt particles from the filtration material. The bell-shaped lower end makes the transporting of a mixture of dirty filtration material and water to the top of the filtration unit more efficient than with the conventional straight tube bottom. The tube receives compressed air from two horizontally positioned inlets positioned 180.degree. from each other. The flat and round target plate makes the scrubbing of filtration material more efficient, while a baffle prevents the filtration material from being ejected from the washbox.

Abstract: A biological purification process, a secondary treatment of partially cleaned waste water for example, is carried out in a porous bed of loose granules which float in the liquid. The granules are continuously washed to remove coagulated impurities by means of a small quantity thereof being entrained from the top of the bed in a small volumn flow of the effluent of the process, mixed with the inflowing impure liquid and then returned to the bottom of the bed. Excess reaction gas may also be delivered to the bed via the inflowing liquid and unreacted gas collected for reuse.

Abstract: Air grid systems for distributing a gas within treatment systems such as underdrain filters and contact clarifiers is disclosed. The air grid is supported from above so that it can be lowered into position and thus modified or repaired. Additionally, this feature permits retrofitting an air grid into an existing system, such as an underdrain filter, in which the bed of media overlying the underdrain is not upset by the installation. Thus, methods of installing or retrofitting air grid systems are also disclosed. In another aspect of the present invention, the air grid is comprised of an air manifold connected to air laterals by a spreader conduit that is inserted through a smooth bore in the walls of the manifold, thereby providing a simple and easy to manufacture structure that avoids problems found in prior art components.

Abstract: A deep bed filter system comprising a plurality of filter media beds, each having a respective media regeneration sub-system that includes some components associated with an individual filter bed and other components that are shared with all filter beds in the system, thereby improving the utilization of available space and lowering the materials and labor costs relative to known systems. A central column extends upwardly along the axis through the upper and lower portions of the vessel, thereby defining an annular volume extending substantially from the bottom of the vessel through the upper and lower portions. A plurality of distinct tubes extend through the central column, with each tube having a lower, intake end situated at the bottom for drawing dirtied filter media from the lower portion of the vessel into the column and transporting the drawn media upwardly through the column to a second discharge end at an elevation above the filtrate level of the filtrate region.

Abstract: An apparatus for treating water includes a vertically extending contact vessel, wherein water is contacted with ozone, and a return vessel which contains a column of water of a sufficient height to drive water through downstream filtering stages. Ozone is removed from the water and the rate of ozone injection is monitored and automatically adjusted so that no great amount of ozone remains in water entering the filtering stages. The ozone is generated in elongated elements that are cooled by the process water and that are positioned to serve as a static mixer for such water.

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 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: An improved reactor for treatment of wastewater having an influent line for wastewater, and effluent line for treated wastewater, and an aerobic bed fluidized by wastewater from the influent line. The bed is located between the influent line and the effluent line and contains particulate media seeded with a layer of bacteria. The improved reactor consists of an internal particulate media cleaning means located between the bed and an outlet to the effluent line for creating turbulence which shears excess biomass from the particulate media within the cleaning means and permits controlled exit of the excess biomass from the cleaning means and the reactor while maintaining cleaned media within the reactor. The internal particulate media cleaning means has at least one cylindrical screen with a longitudinal passage therethrough. The screen is respectively engaged to an inner periphery of the reactor above and below an outlet to the effluent line by gaskets fixed on opposite ends of the screen.

Abstract: A gas is blown into a filter (1) having a granular filter bed such that the gas flows into the bed along at least one elongate free edge disposed in the bed.

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 filtration device 5 is provided in the state being submerged in slurry comprising adsorbent component stored in a reaction tank 1. The filtration device 5 incorporates a plurality of filtering-membrane elements 8 each comprising a filtering membrane 10 having less than 0.1 .mu.m of through-hole diameter. These filtering-membrane elements 8 are vertically disposed in parallel with each other at predetermined intervals between surfaces of adjoining filtering membranes 10. A suction pump 14 is provided by way of linkage with the filtering-membrane elements 8 via a suction tube 13 for sucking processed liquid. A gas-dispersing device 16 is disposed below the filtering-membrane elements 8. A blower 18 is provided in linkage with the gas-dispersing device 16 via a blowing duct 17. An adsorbent regeneration apparatus 21 and an adsorbent feeding pump 22 are respectively interposed on the halfway of an adsorbent circulation duct 20.

Abstract: A solid-bed reactor for biological sewage treatment has an intermediate floor which carries floor jets and by means of which the solid bed can be backwashed. The intake for the sewage is above the solid bed. Aeration orifices are integrated into the floor jets, and gas bubbles can be introduced by the orifices in the upper portions of the floor jets without thereby giving rise to instability phenomena. To ensure stable uniform distribution of aeration throughout the reactor, the clear cross-section in the entire intake region of each floor jet must be such that above the aeration orifices the flow of outgoing water does not impede the ascent of the gas bubbles.

Abstract: A system for distributing both gas and liquid in separate conduits within an underdrain filtration system is disclosed. A tubular liquid conducting conduit also contains a separate air conduit. Extending from each conduit are, respectively, liquid conducting laterals and air laterals. The system is placed within a bed of gravel at the bottom of a filter bed and acts as conventional underdrain blocks and air grids. In a downflow mode, effluent is filtered as it passes through the filter media and filtered water is collected through orifices in the liquid conducting laterals, which in turn feed into the liquid conducting conduit to form a filtrate stream. In a backwash mode, backwash liquid flows through the liquid conducting conduit, out the laterals and up through the filter bed. During backwash, air may be introduced through the air conduit and laterals and rise through the filter media to enhance the effectiveness of the backwash operation.

Abstract: In a travelling bridge filtration system including a tank divided into a plurality of adjacent filter cells, each of the cells containing filter media, a travelling bridge carriage located above the tank and movable along the tank, the carriage supporting a backwash hood engageable with each of the filter cells, the improvement comprising a liquid backwash pump for causing backwash liquid to flow through the cell in a first backwash direction counter to a second filtration direction, and for causing backwash air to be drawn into the cell and to flow in the first direction with the backwash liquid.

Abstract: A self-supporting modular underdrain member for use in a liquid filtration system comprises a main body or housing including a pair of longitudinally extending inclined walls which may have a pair of generally triangular transverse walls connecting the inclined walls to one another, the inclined walls each being provided with a pair of longitudinally extending recesses and a plurality of orifices communicating with each of the recesses. A pair of flanges are connected to the inclined walls for attaching the underdrain body to a floor surface so that the inclined walls, any transverse walls and the floor surface define a cross-sectionally triangular underdrain chamber. Two pairs of elongate cover plates are attached to the inclined walls over the recesses to form in each of the inclined walls a pair of longitudinally extending plenums for the equalization of backwash air and water flow. Each of the cover plates being provided with a plurality of spaced slots.

Abstract: An improvement for a filter system which distributes backwash fluid uniformly throughout a bed of granular media is disclosed. The filter system includes a distributor positioned beneath and supporting the media, with the distributor having a plurality of walls which define a primary horizontal conduit and a secondary horizontal conduit. At least one of the walls which define the conduits contains metering orifices that connect the primary conduit to the secondary conduit. The improvement includes at least one baffle positioned within the primary conduit to facilitate uniform flow of backwash fluid from the primary conduit through the metering orifices into the secondary conduit. The baffle may comprise flanges extending from the walls which define the primary conduit normal to a fluid flow direction in the conduit. Alternatively, the baffle may include posts positioned within the conduit.

Abstract: An underdrain lateral for a liquid purification system is described. The lateral has three chambers, a primary chamber, a compensating chamber, and gas chamber. Turbulence is minimized during cleansing of the purification media by isolating the gas from the liquid and the backwash liquid. This is accomplished by feeding gas into the gas chamber so that the chamber is occupied by gas only during cleansing. Orifices in the wall between the primary and compensating chambers and in the baffle between the compensating and gas chambers provide compensation for even distribution of liquid in the lateral. The design also enables the use of cut outs in the gas chambers to equalize gas pressures and flow among the laterals and throughout the system bed and cut outs in the primary chambers to equalize liquid pressure and flow among the laterals and throughout the system bed.

Abstract: A deep bed upflow filter (10) for removing suspended solids from an influent stream to provide a clean filtrate, comprising an upright vessel (12) having a vertical axis (14), top and bottom ends (16,18) and contiguous upper (20), lower (22), and intermediate (24) regions between the ends. The upper region contains filtrate (26) up to a first elevation (28) and an outlet (30) for drawing the filtrate out of the vessel. The intermediate region contains particulate filter media (32) for removing the suspended solids from influent moving upwardly through the media as the media, dirtied with solids, moves downwardly into the lower region. The lower region is generally tapered (36) inwardly toward the vessel bottom and contains dirty media (34) that has moved downwardly from the intermediate region. Influent is introduced (44) between the intermediate and lower regions, and the dirty media is collected (46) at the bottom and transported (50) to a regenerative washing compartment (52).

Abstract: An improved cap for underdrains in gravity filters has a top surface and a bottom surface with a plurality of tapered screen members defining slots in the top surface. The slots provide communication with the filter bed without passage of fine grain filter media therethrough. The screen members are inclined with respect to horizontal to define a plurality of raised portions in the top surface, each raised portion defining a distribution chamber above the orifices in the distributor. The cap may be included in a capped filter underdrain block having a plurality of ribs and orifices on a top wall of the block. The cap rests on the ribs and cooperates with them to define distribution chambers above the orifices in the top wall of the block. The distribution chambers promote intermixing of air and water prior to introduction to the bed, and the ribs finely meter backwash fluids for even distribution of backwash fluids throughout the entire filter bed.

Abstract: A granular filter is arranged for filtration of suspensions where the flow through the bed is horizontal. The bed depth is less than about 12 cm and the media particle size is less than about 0.6 mm. Pollutants trapped by the media particles are removed by a washing device capable of operation during the filtration process.

Abstract: A process for the treatment of water using a granular bed (3) of granular support materials of a volumic mass less than that of the water to be treated. According to this process, each washing cycle comprises interrupting the withdrawal of treated water and stopping the feed of water to be treated in such a manner that the granular bed (3) floats in a given volume VL of water, admitting cleansing air into the reactor for assuring agitation of the floating bed, interrupting the admission of air in order to permit a separation of the granular materials and sediment by their difference in volumic mass, with decantation of said sediment and flotation of said materials, and evacuating the sediments at the base of the reactor as well as the water contained therein for evacuating the granular bed (3).

Abstract: An improved multi-stage treatment system for biological denitrification of and suspended solids removal from water includes a biological reactor containing rigid media supporting denitrifying bacterial growths, an aeration chamber and an automatic backwash filter. In use, methanol or other carbon source containing influent water flows into the reactor beneath the rigid media and upwardly in contact with said bacterial growths to cause nitrates and nitrites contained therein to be converted into nitrogen. The denitrified water is then aerated in the aeration chamber and subsequently filtered by downward flow through the automatic backwash filter.