Abstract: The present invention relates to a device for tangential filtration of a fluid to be treated and to be separated into a filtrate and a retentate, comprising at least one filtration element which comprises at least one inlet for a fluid to be filtered and at least one outlet for the retentate having circulated the filtration element, wherein said element is incorporated in a circulation loop so that at least a part of the retentate is reinjected into the fluid to be treated before being introduced into the filtration element. a module of filtration into which the circulation loop is integrated and realized by a series of filtration elements in forward direction and a series of filtration elements in backward direction, forming forward and backward circuits.

Abstract: A liquid filtering apparatus is placed in a vessel having a bed of filtration material, the bed comprising at least two different sizes of filter media wherein the filtration material is stratified using upper and lower spaced apart inverted cones so that the unfiltered liquid first contacts coarse grained filtration material and then finer grained filtration material. The apparatus includes an intake for introducing unfiltered liquid that includes a washbox, an airlifting tube extending from the washbox and including an intake end and means for introducing a primary gas to the airlifting tube, the airlifting tube passing through a central pipe, which extends from just below the washbox to a position just above the intake end. The apparatus is devoid of screen cartridges. Methods of filtering and cleaning the filtration material are also disclosed.

Abstract: A desalination system and method are based on the biological mechanism occurring in the mammalian kidney which utilizes colloid osmotic pressure and hydrostatic pressure to recover diluted salt solution from a concentrated one. The desalination system includes fluidly connected chamber compartments, one of which is filled with a charged substance, for example, a charged colloid polymer, to form a colloid salt solution when filled with the concentrated salt solution. Peripheral chamber compartments are filled with the concentrated salt solution. A system of semi-permeable membranes, not permeable to the charged substance, separate the chambers one from another. The system operates in the filling, equilibration, dilute, and collecting cycles which are controlled by opening and closing of the semi-permeable membranes. Desalination is based on the transfer of water due to osmotic pressure gradient across the membranes and is driven by hydrostatic pressure, thus providing energy efficient process.

Abstract: A microfiltration apparatus and method for separating cells, such as circulating tumor cells, from a sample using a microfiltration device having a top porous membrane and a bottom porous membrane. The porous membranes are formed from parylene and assembled using microfabrication techniques. The porous membranes are arranged so that the pores in the top membrane are offset from the pores in the bottom membrane.

Abstract: A fluid treatment device, system, and process are described that provide a filtered, metal-depleted (treated) fluid. The system includes two pairs of tanks that are piped and valved to allow one pair to fill/react while the other pair decants/discharges, which provides a continuous flow of metal-depleted (treated) fluid. Power requirements are minimal since fluid is pumped at a low head pressure. The design has applications in the potable water, industrial, mining, chemical and environmental sectors.

Abstract: A liquid filtering apparatus is placed in a vessel having a bed of filtration material, the bed comprising at least two different sizes of filter media wherein the filtration material is stratified using upper and lower spaced apart inverted cones so that the unfiltered liquid first contacts coarse grained filtration material and then finer grained filtration material. The apparatus includes an intake for introducing unfiltered liquid that includes a washbox, an airlifting tube extending from the washbox and including an intake end and means for introducing a primary gas to the airlifting tube, the airlifting tube passing through a central pipe, which extends from just below the washbox to a position just above the intake end. The apparatus is devoid of screen cartridges. Methods of filtering and cleaning the filtration material are also disclosed.

Abstract: An apparatus for treating a liquid containing impurities may comprise: a filtering chamber for receiving liquid containing impurities, the filtering chamber containing granular media and configured to permit the granular media to interact with the liquid containing impurities, thereby removing impurities from the liquid to produce filtrate; a filtrate section in communication with the filtering chamber for receiving the filtrate, the filtrate section being in communication with a first outlet for outflow of the filtrate; a gas supplying system for delivering gas to the granular media in the filtering chamber for transport of a portion of the granular media to a granular media washer; and a reject section in communication with the granular media washer for receiving a reject mixture comprising liquid and impurities from the granular media washer. The reject section may be in communication with a second outlet for outflow of a portion of the reject mixture.

Abstract: A wastewater treatment method in which magnetic flocs are formed by adding to wastewater an inorganic flocculant, magnetic particles, and a high molecular polymer as a polymeric flocculant, and the magnetic flocs are collected with magnetic force to thereby obtain treated water having the magnetic flocs removed from the wastewater, wherein the improvement comprises that the magnetic particles are added to the wastewater after adding the inorganic flocculant to the wastewater to flocculate suspended solids in the wastewater, after that or substantially at the same time as the magnetic particles are added, the high molecular polymer is added to the wastewater, and flocculates of the suspended solids and the magnetic particles are combined with each other with the high molecular polymer to thereby obtain the magnetic flocs.

Abstract: A method and an apparatus for treating a liquid containing impurities may include a filtering chamber configured to permit granular media to interact with liquid containing impurities, thereby removing impurities from the liquid to produce filtrate; a filtrate section for receiving the filtrate; a gas supplying system for delivering gas to the granular media in the filtering chamber for transport of a portion of the granular media to a granular media washer; a reject section in fluid communication with the granular media washer for receiving a reject mixture comprising liquid and impurities from the granular media washer; and a control unit that is configured to determine whether the portion of the granular media is being transported properly based on an amount of reject mixture in the reject section.

Abstract: Methods and apparatus for removing contaminants from liquid using a continuously circulating stream of purifying media are disclosed. In one embodiment the method includes mixing a regenerated purifying media with a contaminated liquid containing diverse contaminants; co-currently transporting the purifying media and the contaminated liquid in a mixed state; removing, using the purifying media, while co-currently transporting the purifying media and the contaminated liquid, contaminants from the contaminated liquid so as to produce a mixture of a decontaminated liquid and a contaminated purifying media; and separating contaminated purifying media from the decontaminated liquid. In addition, the contaminated purifying media is contacted in counter current fashion with a regenerant solution so as to produce a regenerated purifying media and the regenerated purifying media is returned to the mixing step, whereby the continuously circulating purifying media selectively removes contaminants from the liquid.

Abstract: Exemplary systems and methods relating to washboxes are described.

Abstract: Exemplary systems and methods relating to washboxes are described.

Abstract: The present invention relates to a process for the treatment of liquid effluents laden with hydrocarbons, which comprises: feeding the effluents into a treatment tank; supplying the treatment tank with a reversible sorbent having a defined particle size; mixing the effluents with the reversible sorbent in the treatment tank in order to load said reversible sorbent with the hydrocarbons in the effluents; removing the hydrocarbon-laden reversible sorbent from the top of the treatment tank; extracting the treated effluents from the bottom of the treatment tank; and separating the hydrocarbons from the laden reversible sorbent from the treatment tank.

Abstract: A separation apparatus comprising, a series of compartments for holding particulate separation material, arranged so as to allow fluid to flow through the compartments in a primary direction from a first compartment in the series to a last compartment in the series, feed means for directing a flow of the fluid into the first of the series of compartments in the primary direction, barrier means for preventing flow of particulate separation material between compartments in the primary direction, and a pumping assembly arranged to pump a mixture of the particulate separation material and the fluid from the first compartment into a recovery stage.

Abstract: A valuable resource recovery system includes an engineered powder supply unit that supplies an engineered powder into drainage water (the engineered powder can adsorb a valuable resource and can be desorbed from the engineered powder), an agitation unit that agitates the drainage water supplied with the engineered powder, an engineered powder separation unit that separates the engineered powder from the drainage water agitated by the agitation unit, an engineered powder collection unit that collects the engineered powder separated by the engineered powder separation unit, and a desorption-recycle unit that desorbs the valuable resource from the engineered powder collected by the engineered powder collection unit to recycle the engineered powder and the valuable resource. According to the system, the valuable resource can be desorbed from the engineered powder and then recycled.

Abstract: Exemplary systems and methods relating to washboxes are described.

Abstract: A water treatment process comprising: (a) providing bioactive material in waste water, the bioactive material containing microorganisms capable of removing one or more impurities from the waste water, wherein at least 40% by volume of said bioactive material in said waste water is in granular form; and (b) passing a portion of the waste water through a membrane separator, whereby the membrane separator prevents the bioactive material from passing therethrough.

Abstract: A method and apparatus for separating purifying media from a treated fluid. The method includes transporting the purifying media and the treated fluid along a substantially horizontal direction while a substantial quantity of purifying media fall along a substantially vertical direction relative to the treated fluid to generate a concentration of purifying media below the treated fluid. The falling purifying media are collected while releasing the treated fluid so as to separate the purifying media from the treated fluid.

Abstract: Systems and methods are provided for the removal of a contaminate from an aqueous medium using a zeolite-based sorption column. The systems and methods include an optimized relationship between the hydraulic loading, zeolite mesh size, distribution of zeolite mesh sizes and zeolite bed volume expansion to provide a highly effective sorption column that resists clogging while increases capacity.

Abstract: Apparatus for treating liquid by contact with a particulate adsorbent material comprises a regeneration chamber (10) within a reservoir (2) for liquid to be treated. Adsorbent material is recycled along a path including passage through the regeneration chamber (10) and in a body of liquid in the reservoir to contact and treat the liquid. The adsorbent material is capable of regeneration, and the regeneration chamber (10) is defined between two electrodes (36, 38), which can be coupled to a source of electrical power. The treatment process can be continuous with liquid flowing through the reservoir while the adsorbent material is recycled and regenerated. Alternatively, individual quantities of liquid may be treated on a batch basis. A plurality of regeneration chambers may be arranged within a common reservoir, such as in a bank of chambers aligned along an axis thereof.

Abstract: The present disclosure is directed towards systems and methods for the treatment of wastewater. A system in accordance with one particular embodiment may include a front end system including at least one resin tank configured to contain an ion exchange resin configured to target a particular metal. The at least one resin tank may be configured to receive an output from an oxidation reactor configured to receive a flow of wastewater from a wastewater producing process. The system may further include a central processing system configured to receive a saturated resin tank from the at least one resin tank. The central processing system may further include a vacuum filter band system configured to receive a slurry from the saturated resin tank and to provide a cascading resin rinse to the slurry. The central processing system may further include a repetitive stripping system configured to receive a metal-filled purification unit from a metal specific purification system.

Abstract: The present disclosure is directed towards systems and methods for the treatment of wastewater. A system in accordance with one particular embodiment may include at least one resin tank including an ion exchange resin configured to target a particular metal. The at least one resin tank may be configured to receive an output from an oxidation reactor configured to receive a flow of wastewater from a wastewater producing process. The system may further include a vacuum filter band system configured to receive a saturated resin tank and to apply a water rinse to the resin to generate a resin slurry, the vacuum filter band system including a vacuum filter band configured to receive the resin slurry. Numerous other embodiments are also within the scope of the present disclosure.

Abstract: Biological nutrient removal (BNR) in wastewater treatment to remove carbonaceous substrates, nutrients and phosphorus, has recently become increasingly popular worldwide due to increasingly stringent regulations. Biological fluidized bed (BFB) technology, which could be potentially used for BNR processes, can provide some advantages such as high efficiency and compact structure. This present invention incorporates the fixed-film biological fluidized bed technology with the biological nutrient removal in a twin liquid-solid fluidized bed, which has achieved the simultaneous elimination of organic carbon, nitrogen and phosphorus, in a very efficient manner and with very compact space requirements. The BNR-LSFB has two fluidized beds, running as anoxic/anaerobic and aerobic processes to accomplish simultaneous nitrification and denitrification and to remove carbonaceous substrates, nutrients and phosphorus, with continuous liquid and solids recirculation through the anoxic/anaerobic bed and the aerobic bed.

Abstract: The invention is directed to a method and apparatus for treating wastewater. The wastewater treatment system includes a bioreactor including activated carbon and a first biological population. The wastewater treatment system may also include a membrane bioreactor and/or a wet oxidation unit.

Abstract: Apparatus for treating liquid by contact with a particulate adsorbent material comprises a regeneration chamber (10) within a reservoir (2) for liquid to be treated. Adsorbent material is recycled along a path including passage through the regeneration chamber (10) and in a body of liquid in the reservoir to contact and treat the liquid. The adsorbent material is capable of regeneration, and the regeneration chamber (10) is defined between two electrodes (36, 38), which can be coupled to a source of electrical power. The treatment process can be continuous with liquid flowing through the reservoir while the adsorbent material is recycled and regenerated. Alternatively, individual quantities of liquid may be treated on a batch basis. A plurality of regeneration chambers may be arranged within a common reservoir, such as in a bank of chambers aligned along an axis thereof.

Abstract: A system and method are provided for removing particulates from a fluid treatment basin. The system can include a first continuously inclined surface configured to be substantially submerged in fluid in the fluid treatment basin. A base can be provided to which the first continuously inclined surface is connected. At least one orifice is formed in the base. In addition, a second continuously inclined surface can be connected to the base on a side opposing the first continuously inclined surface. The second continuously inclined surface may be substantially submerged in fluid in the fluid treatment basin. A discharge conduit can be connected to the orifice in order to discharge fluid and particulates gathered via the orifice.

Abstract: A method and system for treating water or wastewater to remove both soluble BOD and suspended solids. The method entails directing first and second water or wastewater streams to a treatment system including an activated sludge system and a ballasted flocculation system. The first water or wastewater stream is directed to the activated sludge system which includes at least one reactor and a clarifier. The second water or wastewater stream is directed to a ballasted flocculation system. Mixed liquor or activated sludge is directed from the activated sludge system to a mixing chamber that is located upstream from the ballasted flocculation system. The water or wastewater of the second stream is mixed with the mixed liquor or activated sludge in the mixing chamber. The mixed liquor from the mixing chamber is directed to and through the ballasted flocculation system. In the end, the soluble BOD in the second water or wastewater stream is reduced and suspended solids in the water or wastewater are also reduced.

Abstract: A biological removal method of phosphorus and nitrogen includes supplying a mixture gas into a gas holder. Inflow water and return water are supplied into the gas holder to make the mixture gas dissolved in the inflow water and the return water. The return water was provided from a granulation biological reaction tank. The inflow water and the return water including the dissolved mixture gas are transported to the granulation biological reaction tank. A nitrogen-based component is removed from the inflow water and the return water using methan-oxidizing bacteria granulated in the granulation biological reaction tank. Treated water without the nitrogen-based component is transported to an anoxic tank for treatment, and discharged from the anoxic tank.

Abstract: Exemplary systems and methods relating to washboxes are described.

Abstract: The present invention relates to a microstructure arrangement for the bubble-free filling with a liquid of at least one system for draining off liquids. The arrangement has an inlet for the arrangement to be connected to a system for the supply of liquids and at least one outlet for the arrangement to be connected to the at least one liquid-discharging system. The arrangement has a transition region, through which the liquid can be transported from the inlet to the at least one outlet. At a start of the transition region, at least one first microstructure element for producing a point with increased capillary force is provided, in order to achieve gap-free wetting of the areas bounding this point with increased capillary force, in particular side walls, a cover and/or a bottom.

Abstract: A device for the treatment of an influent with a porous media. The influent passes radially through the porous media and into an internal volume of the device. The treated influent then passes through an open check valve in the internal volume, and then to downstream equipment. During a backwash operation, a backwash fluid is passed into the internal volume of the device in a direction to close the check valve. The blocked path in the internal volume of the device causes the backwash fluid to pass radially outwardly into the porous media and fluidize the same.

Abstract: A continuous flow reactor or method promotes aerobic granule formation. The reactor may comprise three or four zones that may comprise one or more of an aerobic zone, an alternately aerobic and anoxic zone or discrete aerobic and anoxic zones, and a settling zone. The reactor may have a single sludge removal flow. An anaerobic zone may be located at the bottom of a mass of settled granules. Feed may be introduced through the settled granules generally in a plug flow. An aerobic/anoxic zone may be structured or operated partially like a continuously stirred tank reactor (CSTR) but with aeration varying in space or time. Sludge granules may move intermittently from an aerobic zone to an aerobic/anoxic zone, for example by an air lift pump. A settling zone may have an upflow of >4 m/hr or >5 m/hr and wash off flocculated biomass.

Abstract: In one embodiment, a reactive filtration method includes continuously regenerating a reactive filter media while simultaneously filtering contaminants from fluid flowing through the filter media. In one embodiment, regenerating the reactive filter media comprises mixing metal granules with the filter media and agitating the mixture. In another embodiment, regenerating the reactive filter media comprises introducing a metal in the fluid flowing through the filter media and agitating the filter media. In one embodiment, a method for removing phosphorus, arsenic or a heavy metal from water includes introducing a metal salt reagent into the water at a molar ratio of 5:1 to 200:1 to the phosphorous or the arsenic in the water and passing the water through a bed of moving sand.

Abstract: Systems, apparatus and methods for treating a contaminated fluid stream are provided. The systems may include a treatment column fluidly interconnected to a regeneration column, the regeneration column being adapted to continuously receive solid spent media from the treatment column to continuously regenerate such solid spent media.

Abstract: Disclosed is a device for the production of alkylate(s) by sulfuric acid alkylation of at least one isoparaffin such as isobutane with at least one olefin, such as butylenes. The device includes a mixing chamber for preparing a mixture of the isoparaffin with recycled reaction products. It also includes an emulsion chamber for preparing a first hydrocarbons-in-sulfuric acid emulsion, where the mixture prepared in the mixing chamber is injected in multiple parallel jets into a sulfuric acid composition. The device further includes a pre-reaction chamber for preparing a second emulsion, where a given portion of the olefin is injected in jet streams into the first hydrocarbons-in-sulfuric acid emulsion coming from the emulsion chamber.

Abstract: Systems and methods are provided for the removal of a contaminate from an aqueous medium using a zeolite-based sorption column. The systems and methods include an optimized relationship between the hydraulic loading, zeolite mesh size, distribution of zeolite mesh sizes and zeolite bed volume expansion to provide a highly effective sorption column that resists clogging while increases capacity.

Abstract: A process for continuous countercurrent ion exchange comprises piping a contaminated feed stream into a closed loop ion exchange contactor. The contactor is an ion exchange bed that has three or more reaction segments. The segments are comprised of at least an adsorption segment for treating the contaminated feed stream, a regeneration segment for stripping the contaminant ions from the resin bed, and a pulse segment for advancing the resin bed. Simultaneously, the feed stream is moved through the contactor in the same direction as the regeneration stream. Measuring the quality of this treated feed stream after it exits the contactor monitors the treatment capacity of the resin bed. In response to this quality measurement, the regenerated resin bed is advanced in the pulse segment of the contactor. The spent brine is recycled back to the contactor until the final effluent brine is highly concentrated. After the resin stops advancing, the feed stream and regeneration stream resume flow.

Abstract: A process and an apparatus for efficiently recovering magnesium ammonium phosphate (MAP) crystals of high purity and good quality in the technique of removing phosphorus and the like as MAP crystals from wastewater containing high concentration organic substance, phosphorus and nitrogen such as a digested supernatant liquor of human waste sewage and septic tank sludge, a digested liquor of sludge, chemical plant wastewater, and simultaneously recovering the MAP crystals.

Abstract: Biological nutrient removal (BNR) in municipal wastewater treatment to remove carbonaceous substrates, nutrients and phosphorus, has recently become increasingly popular worldwide due to increasingly stringent regulations. Biological fluidized bed (BFB) technology, which could be potentially used for BNR processes, can provide some advantages such as high efficiency and compact structure. This present invention incorporates the fixed-film biological fluidized bed technology with the biological nutrient removal in a liquid-solid circulating fluidized bed, which has achieved the simultaneous elimination of organic carbon, nitrogen and phosphorus, in a very efficient manner and with very compact space requirements.

Abstract: Provided is an apparatus and method for performing tertiary treatment of sewage based on porous filtering media. The apparatus for performing tertiary treatment of sewage based on porous filtering media includes a reaction tank for receiving effluent wastewater from a primary settling tank; and porous filtering media, which is located in the reaction tank and has a predetermined size of surface area and opening, for settling suspension in the effluent wastewater and removing organic matter and nutritive salts included in the suspension.

Abstract: A device for the treatment of an influent with a nonbonded media, and when the media becomes spent, the media is fluidized with a backwash fluid. Concentric inner and outer perforated cylinders contain a column of media therebetween. The influent is passed radially inwardly through the column of media and into the lower portion of the inner perforated cylinder, where the effluent is removed from the device. During a backwash operation, a backwash fluid is forced into the lower portion of the inner perforated cylinder, radially outwardly into the column of media to provide an upwardly directed drag force. When the drag force exceeds the buoyant weight of the media, the media is fluidized so that the contaminants can be removed therefrom by the backwash fluid.

Abstract: Apparatus and method are disclosed for introducing ion exchange or other particulates into compartments of an already-assembled electrodeionization or comparable stack by modulating a flow of slurry into the compartments with slugs of gas such as air. The air propels liquid through the cells, scavenging ponded liquid so that the particulates (which are retained, e.g., by a strainer or obstruction, in compartment of the apparatus) are deposited as well-packed beds to fill the compartments. Pressurized air filling protocols may deliver discrete slugs of slurry between bursts of air, and the direction of filling may be periodically reversed to diminish particle bed non-homogeneities or settling gradients that arise during transport. The slugs of air may be applied in the direction of slurry flow, in the reverse direction, or both. Different slurries may be transported in a sequence to form layered and packed beds of enhanced utility.

Abstract: A process for preparing an ion-exchangeable media within a moving-bed or simulated moving-bed device, which can create a true or simulated media flow, comprising the steps of packing the bed with ion-exchangeable media and passing a solution, containing a mixture of ionic species, through the media, wherein the solution is passed partly or completely counter-current to the media flow direction such that the ionic species are loaded to a desired level upon equilibration.

Abstract: Water is separated from an emulsion of water and oil by passing the emulsion through a bed of superabsorbent polymer granules which break the emulsion and absorb water from the mixture of water and oil. An apparatus for separating water from an emulsion of water and oil has at least one separation cell containing a bed of super absorbent polymer granules.

Abstract: A novel system, apparatus and method of operation for use in watercraft, terrestrially bound motor vehicles and fixed based land applications where water from a live well or bait tank is withdrawn, filtered, climactically controlled and conveyed through a water conditioning unit containing in part a heat exchanging unit with a generally serpentined contour water passageway, the water passageway formed and structured in a manner to allow water, or another fluid within the passageway to abut and surround a generally serpentine form tubular conduit containing a pressurized refrigerant with the water routed within the passageway maintaining continuous contact with the conduit then exiting the heat exchanging unit returned to the live well tank or bait tank.

Abstract: An enhanced filtration and water conditioning system for a novel bait tank suitable for use in recreational boats, dockside and land based personal and commercial applications wherein water from the tank may be climactically controlled, filtered, purged of sediment, displaced scales and other fish waste and returned to the live well tank. Separate first and second water compartments within the tank function in concert with a second interior wall and a second interior bottom, a dual compartment filtration unit removably accommodated within the interior portion of the second compartment, and filtration unit inflow and outflow water conduits with each of the conduits communicably attaching the filtration unit to the first and said second interior water compartments.

Abstract: The invention concerns a method for purifying aqueous effluents, in particular polluted water, by catalytic oxidation using a three-phase reactor comprising two communicating chambers. The invention is characterised in that it consists in: maintaining the catalyst suspended and continuously circulating it between the two chambers of said reactor, by entrainment under the effect of carrier gas injected into one of said chamber, and in oxidizing the pollutants in contact with the in the other chamber, by injecting a reactive oxidizing gas in said other chamber.

Abstract: Biological nutrient removal (BNR) in municipal wastewater treatment to remove carbonaceous substrates, nutrients and phosphorus, has recently become increasingly popular worldwide due to increasingly stringent regulations. Biological fluidized bed (BFB) technology, which could be potentially used for BNR processes, can provide some advantages such as high efficiency and compact structure. This present invention incorporates the fixed-film biological fluidized bed technology with the biological nutrient removal in a liquid-solid circulating fluidized bed, which has achieved the simultaneous elimination of organic carbon, nitrogen and phosphorus, in a very efficient manner and with very compact space requirements.

Abstract: A liquid filtering apparatus is placed in a vessel having a bed of filtration material and an intake for introducing unfiltered liquid, that includes a washbox, an airlifting tube extending from the washbox and including an intake end and means for introducing a primary gas to the airlifting tube, the airlifting tube passing through a central pipe, which extends from just below the washbox to a position just above the intake end. At least one screen cartridge is oriented in a generally angular downward direction in the bed and is in communication with an effluent chamber defined in part by the outer surface of the central pipe. A reject line extends from the washbox, and an effluent collector extends from the effluent chamber. A method of filtering and cleaning the filtration material is also disclosed.

Abstract: A filtration apparatus comprising a container that houses a filtration tank to which contaminated water is supplied, a cleansing tank, and a screw conveyor disposed within said cleansing tank is provided. Filtration media is housed within the cleansing tank and the container. The cleansing tank has lateral surface openings, lower openings, and an upper opening. When the screw conveyor rotates, filtration media as well as water (contaminated water) is conveyed upward from the lower openings to the upper opening while being agitated. At the same time, filtration media circulates between the cleansing tank and the container and is cleansed. When cleansing is complete, a backwash water supply pump backwashes water, and expels contaminants separated and removed from the filtration media out of the container by an expulsion pump. Lateral surface doors close lateral surface openings by drive means only during cleansing (agitation). This structure increases the filtration area.