Abstract: A blood filter unit having a blood filter holder containing a blood filtering material of a glass fiber filter and a microporous membrane is described. The holder has a blood inlet and a filtrate outlet, and accommodates the blood filtering material so that the microporous membrane is located on the filtrate outlet side and has a space between the blood filtering material and the filtrate outlet. The holder provides means for preventing adhesion of the blood filtering material on the filtrate outlet side. The inventive blood filter unit allows separation of a desired volume of plasma or serum for analysis without interference by the hematocrit value of the blood.

Abstract: The invention relates to a control head constructed for use with rotary filters for controlling separation of filtrate from the filters into adjustable filtrate zones. It is characterized by the fact that at least one filtrate separator (7) is provided, which includes a mechanism for diverting of the flow (9) from axial flow in channels that are axially arranged with respect to the axis of the filter to radial flow without causing entrainment or formation of air bubbles in the diverted flow.

Abstract: The vacuum filtration device has a disposable filter funnel and a disposable filtrate receptacle. The funnel and receptacle are used with a reusable base that is connected to a vacuum source. When the receptacle and funnel are mounted on the base the vacuum is applied through a connecting passage to the receptacle to draw the filtrate from the funnel into the receptacle.

Abstract: A control system for the vacuum cut-off valve of a rotating disc or drum filter is provided. The control system includes an actuator that is connected to the vacuum cut-off valve for adjusting the rotation of the vacuum cut-off valve with respect to the core. The actuator is linked to a controller which receives communications from a vacuum sensor that senses the level of vacuum inside the vacuum box. The controller sends signals to the actuator to either move the vacuum cut-off valve forward (or to a higher position) or rearward (or to a lower position) in response to the vacuum or pressure level inside the vacuum box.

Abstract: A monolithic ceramic filter having a portion of the partition wall of a honeycomb structure exposed with its end face on an outer wall surface of the structure and increased in thickness as compared to the remaining portion of the partition wall to form a flow resistance relaxing portion is disclosed. The monolithic ceramic filter may also have a groove-shaped recess which is separated via a partition from a liquid supply passage of a honeycomb structure and is in communication with the outside of the structure. The flow resistance of the filtrate within the partition walls may be diminished to enable efficient filtration. The filter is produced simply by extrusion molding. There is no necessity of forming holes for discharging the filtrate in some cases.

Abstract: A device and method for removing petroleum based contaminants from the runoff water that passes into a storm drain. The device is a filter apparatus that can be added to a storm drain or a storm drain assembly containing a filter apparatus. The filter apparatus consists of a filter cartridge containing oil absorbing material. The filter cartridge is suspended below the grate of the storm drain by flexible suspension elements such as chains. The top of each of the flexible suspension elements terminate at an attachment element that engages the grate of the storm grate. As a result, the filter cartridge is suspended directly from the grate so as to not disturbed and the position of the grate.

Abstract: The structure has a core which may be a strand or braid, as well as a sheath surrounding the core and defining the exchange surface. Preferred applications are for biomedical equipment such as blood oxygenators and blood purification equipment.

Abstract: A portable, self-contained concrete reclaimer for use at construction sites to collect, break-down, and transport uncured waste concrete washed from concrete delivery equipment, to recycling facilities for use in the manufacture of fresh concrete. The concrete reclaimer comprises a screen having openings sized to separate aggregate from sand, cement and water when uncured waste concrete is washed thereon. The screen being sized to cover a portion of a water tight reclaiming tank having an open top, a closed wall, a bottom continuously sealed to the closed wall, and an upwardly extending partition disposed therein to divide the reclaiming tank into at least two separate, adjacently disposed compartments including a first receiving compartment adapted to receive and contain sand, cement and water, and an adjacent second receiving compartment adapted to receive and contain aggregate separated therefrom during the concrete washing and reclaiming procedure.

Abstract: A unique cylindrical filter assembly (10) having a flow path in one end (31) through a filter media (18) and out the other end with the inlet (12) and the outlet (14) disposed on the longitudinal center line of the cylindrical filter assembly (10) and with the filter media (18) having an elongated annular shape and being disposed around a center chamber (34). Filter assembly (10) includes a pressure relief valve (22) positioned in the center chamber (34) near the inlet port (12) so when the pressure relief valve (22) opens liquid flows directly into the center chamber (34). A housing member (40) can be provided which covers the outlet end (14) and includes louvers (42) for dispersing the liquid as it exits the filter (10).

Abstract: A rotary filter valve is provided with a variable restriction of the timing plate which minimizes bypass gas entering the vacuum system during emergence of the filter elements from the submerged condition.

Abstract: This invention relates to a method and apparatus of denitrification. The apparatus includes a weir block, a denitrification vessel having a wall surface, and filter media having microorganisms on their surfaces. The weir block may have a convex outer surface which is tangentially adjacent to and preferably contiguous with the upper end of the wall, whose lower end is in contact with the water in the denitrification vessel. The method may include passing the wastewater over the convex surface of the weir block, passing the water over the second surface of the substantially vertical wall and into the denitrification vessel while preferably maintaining substantially laminar flow and limiting the dissolved oxygen in the denitrification vessel, preferably to below about 5 mg/L and more preferably to below about 4 mg/L.

Abstract: An apparatus for the decontamination of a subsoil formations, whereas groundwater is produced over long periods of time to remove especially the highly volatile halogenated hydrocarbons, causing contaminants to be flushed out and contaminants separated from the groundwater at the surface. In order to also be able to remove contaminants having higher specific gravities and contaminants with a low solubility in water, it is proposed to vibrate the water saturated soil/rock zone by means of an acoustic transmitter. The acoustic transmitter consists of two plate-like elements as membranes between which there is a coil.

Abstract: There is disclosed a device for both holding a filter element and deflecting and draining filter effluent, which may be adapted to utilize one or more disposable filter cartridges. The device can be used in systems for performing analytical tests which include a filtration step, and is particularly useful in systems for measuring the fouling potential of water containing particulates.

Abstract: A method of producing a fluid purifier membrane module, sheets of membrane material are disposed in layers with intermediate spacer elements in a manner to obtain mutually alternating spaces for contaminated and purified fluid respectively. Mutually adjoining sheets of membrane material (12) are joined together in pairs in a manner to obtain membrane units (10) which include closed cavities (28). The membrane units (10) with associated spacer elements (18, 34) are arranged in a stack. The mutually facing outer surfaces of the membrane units are joined together in zones and in a fluid-tight fashion along at least one line (36) which extends through the walls of the membrane units. The membrane units are perforated along the line in a manner to obtain through the membrane units a passageway (32) which communicates with the cavities (28).

Abstract: The vacuum filtration device has a disposable filter funnel and a disposable filtrate receptacle. The funnel and receptacle are used with a reusable base that is connected to a vacuum source. When the receptacle and funnel are mounted on the base the vacuum is applied through a connecting passage to the receptacle to draw the filtrate from the funnel into the receptacle.

Abstract: An improved filtration apparatus useful in particular for sampling a bulk, fluid, is provided. Advantageously, the filtration apparatus provides an air gap between a filtrate and the filtration medium. As a result, a bulk fluid is protected against potential contamination from the filtrate side of the filtration medium. Also provided is a technique for reducing filtration medium fouling, and for filtrate collection upon demand. Apparatus in accordance with the present invention, is useful, for example, in conjunction with monitoring urea concentration during dialysis.

Abstract: Two porous belts and a plurality of rollers are provided for removing liquid from sludge. The sludge is positioned between the two belts and moved under compression over the rollers thereby causing the liquid to be discharged from the sludge and into a catch basin below. The rollers are relatively positioned to form an upwardly projected undulating contour thereby defining an area under each of substantially all rollers for the placement of liquid deflectors under each roller. An associated method provides steps for positioning sludge between two belts, moving the sludge in compression over rollers to remove liquid from the sludge and deflecting the extracted liquid from a portion of the belts.

Abstract: A spiral wound gas permeable membrane module having a hollow mandrel with a plurality of holes, at least one envelope-like gas permeable membrane wrapped spirally around the mandrel, at least one feed water spacer positioned on the outer surfaces of the spirally wrapped envelope-like membrane, and at least one permeation side spacer provided in the envelope-like membrane. The module contains a partition block for blocking the flow of a gas flowing in the mandrel in its longitudinal direction and a flow regulating wall directing the flow of the gas introduced into the envelope-like membrane through the holes aligned on one side of the partition block so that the gas travels in the envelope-like membrane in a spirally outer direction, then returns in a spiral inner direction and flows into the mandrel through the holes aligned on the other side of the partition block.

Abstract: An espresso machine is proposed which comprises an espresso-making filter (10) capable of being filled with coffee powder and having a sieve (11, 12) with openings (13) of defined cross-sections for retaining the coffee powder when espresso is being made. Means are provided for varying the cross-sections of the openings (13). These means are preferably configured as needles (21) divided along their lengths into at least two portions of different cross-sections so that the openings (13) formed in the sieve (11, 12) can be closed to a greater or lesser extent depending on the penetration depth of the needles (21).

Abstract: A mud cleaning apparatus is set forth and has an upstanding cylindrical housing supported by a frame work with legs. There is a mud inlet line at the top of the housing. Centrally, a motor drives a drive shaft extending vertically in the housing and supporting cascaded circular screens which are rotated. Each screen has mesh openings to remove particles of particular size and mud flows through that screen into a funnel there below and is directed by the funnel into the next screen. Typically, three screens and three funnels are included wherein the bottom funnel connects with an outlet mud line to remove the clean mud. Trash removed from mud flow collects on the screens which are rotated, and such motion couple with vibration imparted to the screens causes the trash to migrate across the screens for ejection from the screens and accumulation in the bottom of the cylindrical housing and removal on a conveyor system.

Abstract: A filtration device for separating filtrate and concentrate from a solution may contain a variable dead stop feature. The apparatus includes a housing with a means for collecting filtrate and a multiple sided filter unit insertable within the housing. The filter unit contains a semipermeable membrane thereon for separating filtrate from concentrate and a means for directing filtrate to a discharge within the housing. The apparatus also contains a means for preventing concentrate within the housing from escaping through the discharge opening of the housing.

Abstract: A cross-flow filtration device which receives a feed stock at a feed end face and separates the feed stock into filtrate and retentate, the device having a structure, preferably a monolith, formed of porous material and defining a number of passageways which extend longitudinally from the feed end face to a retentate end face of the structure. The structure further includes a number of longitudinal filtrate chambers and a filtrate collection volume extending into the structure and communicating with the filtrate chambers. The filtrate chambers are distributed among the passageways to provide low pressure drop flow paths for filtrate flow through the porous material from the passageways to nearby filtrate chambers, and at least some of the passageways are separated from filtrate chambers by intervening passageways, thereby enabling a high ratio of passageway surface area to volume of the device and a high rate of filtrate removal.

Abstract: A spirally wound ultrafiltration filter cartridge system and method which comprises a membrane sheet material forming a closed loop having a one end and an other end with first and second open spacer sheet materials, the membrane sheet material and spacer sheet material wrapped about a perforated center tube, the membrane sheet material sealed at either end by solid resin headers, the filter cartridge forming spirally wound permeate and concentrate flow channels and having a tangential, elongated feed inlet on the exterior surface of the filter cartridge. A concentrate stream is removed from the center tube and a permeate stream is removed from the one end of the closed loop of the membrane sheet material. The method of manufacture comprises spirally winding the closed end loop sheet material and the spacer sheet material about a perforated center tube and sealing either end of the membrane sheet material with a ptting resin.

Abstract: The invention relates to a method for concentrating macromolecular solutions, more particularly of protein molecules, to a defined end volume lying in the ul-range and to a filter for carrying out the method. The liquid phase of any amounts of solutions is pressed through an upright filter leaf. The filtered constituents are directed down through gravity and are collected in a concentrate chamber.

Abstract: An apparatus and method for skimming contaminants from a reservoir of a liquid such as an industrial solvent, including a tubular wand having an end inlet extending into the reservoir, a pressure air line extending along the wand, the air line protruding a side wall of the wand and terminating at a nozzle proximate the inlet, the nozzle being directed into the wand, away from the inlet for producing a vacuum. The wand is adjustably mounted to a base that attaches to the reservoir, and is connected to a vented container for collecting the contaminants that are drawn into the wand. Contaminants can be removed from the surface of the liquid, from proximate the bottom of the reservoir, or from a submerged layer concentrated at an intermediate depth within the reservoir.

Abstract: A spiral-wound pervaporation module, designed to achieve optimum permeate flow throughput. The module is of conventional design and construction, in that it incorporates membrane envelopes, within and between which are channels through which the feed and permeate streams flow. The feed and permeate channels are created by spacers on the feed and permeate sides of the membrane layers. The module is unconventional in that the permeate spacer is tailored for optimum permeate flow throughput. The tailoring is based on the discovery that the total permeate flow throughput from a module passes through a maximum as the resistance to vapor transport of the permeate spacer material is progressively decreased. The resistance to vapor transport along the permeate channel is kept below a value at which it has a significant adverse effect on the membrane flux and the membrane separation properties, yet at the same time the total module throughput is within an optimum range.

Abstract: Disclosed is an adjustable valve for use with filters wherein internal valve partition members effect the relative duration and timing of withdrawal of the atmospheric and vacuum portion of filtrate from the filter. The valve further provides for the distribution of filtrate to clear or cloudy sump wells depending on the concentration of particulate matter contained in the filtrate portions. Timing and apportioning of the filtrate is accomplished by a combination timing plate and valve housing containing movable valve partitions, the valve body being in communication with a vacuum box and atmospheric drains.

Abstract: Method and equipment for filtration of a suspension so that the suspension to be filtered is fed from a feed part (4) onto the filter face of a filter member (5), which moves relative the feed part. The pulp layer is formed on the outer face of the filter member and the filtrate flows into the interior of the filter member, and the pulp layer is removed from the filter member at the removing point. After the pulp removing point (17), before the feed point (4), one or several cleaning points (12) are provided wherein liquid is made to flow through the filter member (5) from the inner face of the filter member to the outer face. The flow rate of the liquid that flows through the cleaning point or points is adjusted higher than the rate of any liquid flow that may flow through the rest of the filter member from the inside-face side to the outside-face side.

Abstract: A cross-flow filtration device which receives a feed stock at a feed end face and separates the feed stock into filtrate and retentate, the device having a monolith with at least one filtrate network. The monolith is formed of porous material and defines a number of passageways which extend longitudinally from the feed end face to a retentate end face of the monolith. The filtrate network includes a number of longitudinal filtrate chambers and one or more filtrate channels which transect the chambers. The filtrate channel communicates with at least one filtrate duct that discharges filtrate from one or both end faces of the monolith. The filtrate chambers are distributed among the passageways to provide low pressure drop flow paths for filtrate flow through the porous material from the passageways to nearby filtrate chambers.

Abstract: An apparatus for dispensing a predetermined amount of a sample into a fluid. The apparatus comprises a chamber which may be inserted into a cuvette. The chamber comprises a membrane or filter ball for dispensing a predetermined amount of a sample into a fluid upon contact of the membrane or filter ball and the sample by the fluid. The fluid is brought into contact with the sample by vortexing the fluid with a vortex mixer.

Abstract: In a disk-type decker that is employed to drain suspensions and that has axially distributed suspension chambers and filtrate chambers that are separated by rotating screen disks and open into a stationary tub, the filtrate chambers are evacuated to increase the throughput of the decker and improve and accelerate drainage. The filtrate chambers are for this purpose divided by radial and axial transverse partitions into individual filtrate-chamber sections distributed along the circumference and sealed off from one another. When the screen disks and hence the filtrate-chamber sections rotate and the sections enter into flow engagement with filtrate outlets at the bottom of the decker, they are simultaneously evacuated, accelerating drainage through the disks. The results are a higher throughput, a lower material density in the filtrate, and lower specific investment costs at the same throughput or material density in the filtrate.

Abstract: A separator element (10) is described, which includes on the side of the incoming flow, before the first hydrophobic filter layer (38) consisting of a microporous membrane with a mean pore size of approximately 15 microns, an outer second hydrophobic filter layer (40) with a mean pore size of approximately 50 microns. With the aid of the second filter layer (40), the larger water drops are first separated from a fluid mixture to be cleaned. The residual small water drops are fully retained at the inner first filter layer (38) and in the sedimentation area (48) they are discharged into the space of the incoming flow.

Abstract: A disk filter including a plurality of rotatable, annular filter disks (3) arranged mutually spaced in an axial direction, and disposed for being partially immersed in a liquid or a suspension to be filtered. Each filter disk comprises a plurality of filter sections (4) which are in communication with axially directed filtrate conduits (2) arranged in the peripheries of the disks (3) for discharge of filtrate. The filtrate conduits (2) are provided with backwash barriers which are adapted to prevent liquid flow from the filtrate conduits radially inwards when the filter sections (4) rise above the liquid surface. The backwash barriers have been achieved by each filter section (4) being connected to an axial filtrate conduit in the form of a pipe (2), the main portion of the cross-section of the pipe at the place of attachment being located after each part of the filter section (4) as seen in the direction of rotation (A).

Abstract: A permeator has a cylindrical body whose filtration chamber accommodates a embrane element. Arranged to both sides from the filtration chamber along the axis of the body are permeate withdrawal chambers, communicating with the membrane element by way of permeate withdrawal pipe branches and each furnished with its own permeate withdrawal pipe branch.

Abstract: A device for the separation of a separable component from a liquid sample for use with an evacuated receptable includes a housing having an interior cavity and a separator membrane dividing the cavity into a first portion and a second portion. The separator membrane has a porosity selected for the desired separation thereacros. An inlet structure is provided for fluid communication between the first portion of the interior cavity and the source of the liquid sample. Communication structure is provided for allowing fluid communication between one of the portions of the cavity and the evacuated receptacle. A rigid receptacle is in fluid communication with the other of the portions of the cavity.

Abstract: A device for the separation of the lighter fraction from the heavier fraction of a liquid sample for use with two evacuated receptacles includes a housing having an interior cavity and a membrane separator dividing this cavity into a first portion and a second portion. The membrane separator has a porosity selected for the desired separation thereacross. An inlet structure is provided for fluid communication between the first portion of the interior cavity and the source of the liquid sample. First structure is provided to allow fluid communication between the first portion of the interior cavity and the first evacuated receptacle. This first structure is opposed from the inlet structure so that liquid passing from the inlet to the first structure travels in a direction along the surface of the membrane. Further structure is provided to allow fluid communication between the second portion of the interior cavity and the second evacuated receptacle.

Abstract: A decker comprises a tank having a thickening drum mounted rotatably therein and including a filtering shell. The inside of the drum communicates with an inlet for feeding mass, whose consistency is to be increased during the thickening process and outlets for discharging the thickened mass after the thickening process. The filtrate separated from the mass being thickened, is arranged in a flow communication from the inside of the thickening drum through the filtering shell of the drum to the bottom portion of the tank. At least one separating member is placed in the bottom portion of the tank outside the drum and forms a partition point or partition line situated transversely with regard to the direction of rotation of the drum and at a predetermined, angular distance from the horizontal plane coinciding with the axis of rotation.

Abstract: An improved gas baffle device is disclosed for use in on-site waste disposal system tanks, such as septic tanks, which can be adjustably mountable to the outlet line of the septic tank. The gas baffle device includes a mounting strap which is readily secured to a pipe extending downwardly from a sanitary tee mounted the tank's outlet line. The mounting strap carries a support post and a gas baffle plate. The baffle plate is maintained over the end of and at an angle to the opening of the sanitary tee pipe. Special connection means on the strap allow the support post to be readily interconnected thereto. This improved gas baffle device is easily and quickly field-installed into a new septic tank, or can be readily retrofitted into an existing septic tank as needed.

Abstract: A method and an apparatus for separating bodies from a liquid in which the liquid is passed through a filter and the bodies to be separated are accumulated on the filter. The filter forms an upper bounding limit of a space therebeneath which is alternately subjected to pressure and vacuum relative to the ambient region above the filter. This is achieved according to one embodiment by producing a reciprocal movement of the filter in the form of an oscillating or pendular movement. The pressurization in the space produces separation of the bodies accumulated on the upper surface of the filter to facilitate their discharge from the filter. The separated bodies can be assisted for discharge by mechanical elements and/or by producing wave motion in the liquid.

Abstract: An apparatus is disclosed for allowing mixing of solutions in low gravity environments so as to carry out crystallization of proteins and other small molecules or other chemical syntheses, under conditions that maximize crystal growth and minimize disruptive turbulent effects. The apparatus is comprised of a housing, a plurality of chambers, and a cylindrical rotatable valve disposed between at least two of the chambers, said valve having an internal passageway so as to allow fluid movement between the chambers by rotation of the valve. In an alternate embodiment of the invention, a valve is provided having an additional internal passageway so that fluid from a third chamber can be mixed with the fluids of the first two chambers. This alternate embodiment of the invention is particularly desirable when it is necessary to provide a termination step to the crystal growth, or if a second synthetic step is required.

Abstract: A membrane filter comprises one or several tubular flow channels (1) for liquid which is to be treated in the filter. The walls of the flow channels consist on the inner side of membranes, which are supported by a supporting structure. An outer casing (2) surrounds the flow channels and limits a collection space (5) for permeate between the casing and the flow channels. According to the invention the flow channels (1) and the said collection space (5) are connected to separate outer circuits, comprising pumps to bring the liquid which is to be filtered (retentate) as well as permeate to circulate concurrently pass the membrane filter. The collection space is filled by filling bodies, which constitute an essential mechanical hinder for the flow of circulating permeate. Means in the form of disks (8) provided with holes, which abut against the outer casing, are arranged at the inlet to the flow channels.

Abstract: A device for the separation of the lighter fraction from the heavier fraction of a liquid sample for use with two evacuated receptacles includes a housing having an interior cavity and a membrane separator dividing this cavity into a first portion and a second portion. The membrane separator has a porosity selected for the desired separation thereacross. An inlet structure is provided for fluid communication between the first portion of the interior cavity and the source of the liquid sample. First structure is provided to allow fluid communication between the first portion of the interior cavity and the first evacuated receptacle. This first structure is opposed from the inlet structure so that liquid passing from the inlet to the first structure travels in a direction along the surface of the membrane. Further structure is provided to allow fluid communication between the second portion of the interior cavity and the second evacuated receptacle.

Abstract: The invention relates to an apparatus for the removal of ferromagnetic materials from liquids, organic or inorganic compounds and mixtures, respectively, mainly fuels, for treating with a magnetic field and reduction of surface tension.The apparatus according to the invention contains a plurality -at least two- coaxial magnets having a hole therein and being in the direction of flow of the liquid and being separated by a disc, as well as housing made of a non-magnetizable material closed at both ends with end-closing means and provided with a bore for passing through the liquid to be treated.

Abstract: A liquid treatment apparatus suitable for dewatering a radioactive sludge includes a cylindrical housing (14) open at one end and defining two ports (24, 26) for the sludge, one near the open end and the other at the closed end. A plug (30) locates in the open end of the housing and supports a module (44) comprising a sealed permeate-collecting chamber (46) through which extend a number of permeable-walled tubes (54), open at each end. The plug defines a header chamber (40) for the tubes (54) which communicates with the one sludge port (24); and defines an outlet duct (62, 38) for the permeate liquid. The apparatus can be installed remotely within a shielded enclosure (12), and the plug and module can be withdrawn without risking contamination of the permeate liquid.

Abstract: A filter element constructed of stainless steel. The element includes a pair of filter media concentrically disposed to receive parallel flow of the filtrant. The element is adapted for disassembly to remove the filter media. The various component parts of the filter element may thereafter be easily cleaned and the filter media replaced. The filter media after being removed may also be cleaned and reused if desired. The component parts include appropriate guard assemblies to protect the filter media during handling and use.

Abstract: Disclosed are spiral-wound membrane cartridge constructions for use in ultrafiltration and reverse-osmosis separation equipment. The membrane constructions include a membrane layer directly bonded to a permeate carrier layer characterized by a channel material having a plurality of parallel ribs extending in a transverse permeate-carrying direction, interconnected by a relatively thin matrix of smaller fibrils. It advantageously reduces resistance to permeate flow to a central collection point, and can be employed to separate both liquid and gaseous fluids.

Abstract: A cross-flow filtration device which separates a feed stock into filtrate and retentate, including a structure of porous material which defines a plurality of passageways extending longitudinally from the feed end of the structure to a retentate end, and a number of filtrate conduits within the structure for carrying filtrate from within the structure toward a filtrate collection zone. The filtrate conduits provide paths of lower flow resistance than that of alternative flow paths through the porous material, and the structure is constructed such that the filtrate conduits are distributed among the passageways to provide low pressure drop flow paths for filtrate flow from the passageways through the porous material to nearby filtrate conduits. The cross-flow filtration device can also be utilized as a membrane support for a device for cross-flow microfiltration, ultrafiltration, reverse osmosis, gas separations or pervaporation. Also disclosed is a method of making such a cross-flow filtration device.

Abstract: The invention concerns a filtering unit comprising a filter diaphragm (11), a backing surface (12) disposed against the diaphragm, and passages through which the liquid to be filtered can be supplied on one side of the diaphragm and the liquid that has drained through the diaphragm can be removed from the opposite side of the diaphragm. As taught by the invention, the backing surface (12) is provided with ridges (13) lying side by side and with grooves (14), moving liquid in the direction parallel to the diaphragm (11), between them and which start in the central part of the surface in different directions and lead to the periphery of the surface, curving in such manner that the spacing of mutually adjacent ridges is substantially constant on the entire area of the backing surface. The backing surface (12) will then to the filter diaphragm (11) lend throughout uniform support.

Abstract: A structure to prevent all manner of debris from entering into and clogging the drain guttering system of a sloping roof dwelling or building; through the use of a fine mesh screening top immediately underlying which is located a gently sloping needle stop permitting only the tiniest grip for any needle which may pierce the screening, assuring that it shall topple over and be blown away with a change in climatic conditions and wind direction. This solid surface gently sloping needle stop leads the rain water to a series of drainage holes beneath the ledge of a needle deflector (preventing needles from reaching the drainage holes) and into the main guttering system through which it flows to and down the downspout.

Abstract: Process for recovering nitrate from surface and ground water, in particular drinking water, by means of biological denitrification, in which the nitrates contained in the water are reduced to gaseous nitrogen in a reactor by means of a biocatalyst having immobilized cells trapped in a gel or polymer. The "micrococcus denitrificans" that is preferably used requires for its metabolism added hydrogen and carbon that is present in the water in the form of dissolved carbon dioxide. Using a biocatalyst of immobilized cells and of the bacterial strain used, expensive after-purification is unnecessary because of increased bacterial count in the pure water outlet, and no undesirable by-products are formed.