FR2689416A1 - Single use filtration strip for waste water - where strip is scrolled across rotating drum mounted in vessel fed by gravity - Google Patents

Abstract

Appts. for filtration of waste water by gravity flow across a single use mobile filtration strip applied to the permeable face (4) of the curved surface (3) of at least one rotating drum (1) on a horizontal axis (X-X1). USE/ADVANTAGE - Used for redn. in level of small particles present in waste water. Efficient filtration of fine particles at high concn. (10 to several hundred mg/l) and high flow rates (10-100m3/h). Low cost operation with long operational runs. Fineness of filtration is below 10 power(-4)m. (claimed).

Description

Wastewater filtration device
DESCRIPTION
The present invention relates to a device for filtering used or charged water.

 The invention relates more particularly to a device making it possible to filter large flows of water loaded with small particles such as for example irrigation water or water coming from purification stations or washing water. which have been contaminated with organic or inorganic products, by various industrial processes.

 The technical field of the invention is that of the manufacture of filters with movable filter elements.

 Numerous filtration devices with mobile filter elements are already known, in particular devices in which the filter media is supported by a permeable cylinder.

Such devices are described in particular in patents FR 1 432 089 (AJEM LABORATORIES), FR 1 460 877 (SOCIETE DES FILTRES
PHILIPPE), as well as in patent applications EP 429 747 (Ralf F.

Peipho Abwassertechnik GmbH) or EP 437 860 (RUEZ Norbert).

 Patent FR 1 432 089 describes a filtration device comprising a drum mounted to rotate in a tank receiving the water to be filtered; the drum is provided on its external cylindrical surface with a filtering medium and is driven by a slow rotational movement; the drum is immersed in the liquid contained in the tank; the filtered materials remain on a filter tape and the filtered liquid passes inside the drum and exits through a journal communicating with a conduit to be sucked up by a pump.

 Patent FR 1 460 877 describes a rotary drum filter which is immersed in the fluid to be filtered and which comprises means making it possible to ensure the supply of the filter continuously with a filtering medium as well as the guiding, washing and recovery of this filter media. The filtered fluid is evacuated by pipes located inside the volume of the drum, which rotate with it and which are in communication with fixed pipes, by means of a sealing device provided in the landing.

 Patent application EP 429 747 relates to a method and a device for filtering solids contained in a liquid and for separating emulsions from sedimented solids; the device comprises a drum provided with openings in its side walls making it possible to introduce chemicals into the internal space delimited by the drum; inside the drum are also located a level controller and an agitator and the external cylindrical face of the drum is in contact with a filter band which is interposed between the external surface of the drum and a circulating endless band.

 Patent application EP 437 860 relates to a rotary drum filtration device of the same general type as that described in the aforementioned patent, which moreover includes specific means for removing particles which have been separated from the fluid and which are contained in the drum and which also comprises a distributor over the entire length of the drum of the flow of fluid to be filtered entering the drum.

The problem not resolved by rotary drum filtration devices of known type is that it makes it possible to filter water loaded with fine particles with great efficiency, in a range of high flow rates; the problem posed also consists in providing a device for filtering charged or used water allowing these results to be achieved at a lower cost, in particular thanks to a very simple construction and which moreover makes it possible to adapt to variations in the incoming flow d water to filter
The solution to the problem posed consists in providing a wastewater filtration device comprising means for the gravity flow of said wastewater through a circulating and disposable filter band.

 Advantageously, a wastewater filtration device comprises at least one rotary drum along a substantially horizontal axis xxl and at least one movable filter strip applied against an external permeable face (or zone) of the shell of said drum, and comprises means for gravity flow of said waste water from the outside of said drum towards the inside of said drum, through said filter band.

 Said device can comprise means (for example hydromechanical) of maintaining an input flow rate of said wastewater, within a predetermined range, and said device comprises means of control (and / or control, and / or regulation) the rotation (preferably the speed of rotation) of said drum (and preferably the driving speed of said filter band) as a function of an input level of said wastewater.

 Advantageously, the device according to the invention comprises at least one tank comprising an inlet compartment and an outlet compartment separated by a substantially vertical partition (substantially perpendicular to said axis xxl) provided with an opening (or cutout) substantially circular through which is arranged (in an adjusted and sealed manner) an impermeable zone (rear) of said ferrule of said drum.

 Advantageously, said drum has a waterproof front bottom in the form of a thin disc which closes a first end of said ferrule, which ferrule is open at its second end (rear end).

 Advantageously, said opening of said partition is provided with a seal (scraper) in contact with the external face of said impermeable zone of said ferrule (and preferably said scraper seal is circular and mounted in a groove provided in a circular flange fixed on said partition).

 Advantageously, the average filtration fineness of said filter band is less than 100 microns (for example of the order of 5 to 50 microns).

 Advantageously, said drum is provided in said permeable zone of said ferrule with a mesh (or mesh, preferably metallic with large meshes), forming a support for said filter strip wound on at least part of the external cylindrical surface of said ferrule.

 Advantageously, said means for controlling the rotation of said drum as a function of said input level comprise a float level detector.

 Advantageously, said means for maintaining said inlet flow comprise a hydromechanical inlet flow regulator comprising a movable shutter (or valve) and return means (comprising for example a spring) of said shutter, and comprise means for easily adjusting accessible from the return force of said return means.

 Advantageously, said filter band is mainly constituted by cellulose fibers forming a parallel veil.

 Advantageously, said filter band is mainly constituted by cellulose fibers and cotton fibers forming a cross-fiber veil.

 Advantageously, the device according to the invention comprises an electric motor for driving said drum and for receiving rollers (or rollers for discharging said strip), by means of driving means such as a device with toothed pulleys and chains.

 A filtration installation according to the invention can comprise at least two filtration devices connected in series in order to ensure cascade filtration.

 Thanks to the device according to the invention, it is thus possible to filter very efficiently water charged with fine particles at a rate for example of 10 to 100 mg of charge per liter of water, and this for flow rates of treated water which can vary from 1 '' order of ten M3 / H up to flow rates of the order of several hundreds of m3 / H approximately.

 Thanks to the device according to the invention, it is possible to reduce the charge of organic or inorganic particles present in the water to be treated, for example by the order of a level corresponding to 60 mg per liter up to a residual charge of the order 20 mg per liter and this at a very low cost using a low cost non-reused filter tape. Furthermore, given that it is possible to have filter strips made of very thin cellulose, polyester, cotton or polypropylene fibers having a very fine filtration and packaged in rolls of several tens or even several hundreds of meters, l 'autonomy corresponding to the use of a roller can be very important, of the order of several hundred hours.

 The numerous advantages provided by the invention are better understood through the following description which refers to the appended drawings which illustrate without any limiting character particular modes of filtration device according to the invention.

 FIG. 1 illustrates in longitudinal transverse view a preferred embodiment of a drum filtration device according to the invention.

 FIG. 2 illustrates a detail of a device for regulating the inlet flow rate of a filtration device according to the invention.

 FIG. 3 schematically illustrates a particular mode of use of the filtration device according to the invention.

 Figures 4 and 5 illustrate in perspective view of particular embodiments of devices according to the invention.

 Referring to Figure i, the filtration device essentially comprises a drum 1 of generally cylindrical shape of axis xxi said drum essentially comprises a ferrule 3 closed at one end (front end) located in the inlet compartment 8 of a tank 7 largely containing said drum, by a solid bottom 13; said ferrule 3 of said drum is open at its second end located near a second compartment 9 or outlet compartment of said tank 7 of said filtration device.

 Said drum i is provided with a shaft 12 mounted on bearings 24 fixed on opposite side walls 23 of said tank 7.

 In Figure 1, said filtration device is shown substantially in external view for the part of Figure 1 located above said axis xxl is substantially in section for the part located below said axis xxl.

 Said ferrule of said cylindrical drum of axis xxl comprises a first part of ferrule 14 which is impermeable to the fluid to be filtered and of length along the axis xxl which is advantageously small, which part 14 of ferrule is tightly connected to said front bottom 13 .

 Said ferrule also comprises a permeable part 4 preferably constituted by a lattice of metallic wires it for example made of stainless steel forming relatively large meshes and serving as a support for a filtering band 2 which is supported on a large part of the external cylindrical surface of said permeable part 4 of said shell 3.

 Said ferrule 3 also includes a second impermeable part 15 situated behind said permeable part 4.

 Said impermeable rear part 15 of said ferrule is linked to said shaft 12 by radial spacers 16 which ensure the rigidity of the drum; said drum being moreover fixed to said shaft by means of said front bottom 13.

 Said drum can be driven in rotation along said axis xxl by means of an electric motor 25 driving said shaft 12 by means of drive means 26 such as for example toothed wheels cooperating with chains as illustrated in FIG. 4.

 In particular embodiments, the length L of said permeable part 4 of said ferrule of said drum can have a value of the order of 0.5 to 2 meters and the diameter D of the ferrule of said drum having a dimension of the same order larger than said length L.

 Said tank 7 in which said drum is largely located comprises, according to the invention, said inlet compartment 8 limited by a bottom 51, said substantially vertical side wall 23 supporting one of said rotational bearings of said shaft of said drum, which wall 23 can advantageously be provided with an inlet flange 43 on which is mounted an inlet flow valve or regulator 35 constituting a particular embodiment of said means for maintaining the inlet flow of said fluid into said compartment. entering a predetermined range; advantageously, during the operation of the filtration device, said level 5 of the fluid in said inlet compartment is close to a horizontal plane (perpendicular to the plane of FIG. 1) containing said axis xxi, and preferably said level 5 is distant (and located above) of said horizontal plane containing said axis xxl of less than a quarter of said diameter D of said drum.

 According to the invention, the fluid to be filtered contained in said inlet compartment 8 penetrates by gravity into the inner part of said drum by passing through said filter strip 2, more particularly the part of said filter strip which rests on a part of the periphery of said ferrule, more particularly on the part corresponding to said permeable zone 4 of said ferrule.

 In accordance with the invention, the filtered water having passed through said filter strip 2 is collected inside said drum and is discharged from the rear of said drum (on the right in FIG. I), that is to say in s 'flowing along and at the bottom of said permeable part 15 of said ferrule 3 until it is collected in the second compartment or outlet compartment 9 of said tank 7 then escape from said compartment and from said tank according to arrow 37 thanks to an outlet flange 44 provided on the wall 23 of said tank.

 In accordance with the invention, the water inlet level 5 is maintained, that is to say the water level located in said inlet compartment 8, at a height for example not far from the height of said axis xxl , so that the height of the filtered water in said outlet compartment 9 is maintained at a height very little greater than the height corresponding to the lower generatrix of said cylindrical drum and / or of said ferrule 3, which height is marked on the figure 1 by the reference 17.

 The device according to the invention comprises means for maintaining said level 5 which may for example comprise a level sensor comprising a float 20 capable of moving vertically while being guided by a rod 22, and the position of said float relative to said rod can be measured or detected by a detector module 21 which can transmit the information corresponding to said input level 5, to a means for controlling the speed of said motor 25 and therefore to thus control the running speed of said filtering strip .

 It can be seen in FIG. 1 that said inlet 8 and outlet 9 compartments are separated by a partition 10 substantially vertical and perpendicular to said axis xxl, provided with an opening 18 of circular shape, which partition is advantageously provided with a flange of partition 46 comprising in an internal groove a seal 19 sealing between said compartments 8 and 9 while allowing the rotation of said drum, which seal 19 is maintained in permanent contact with the external face of said impermeable zone 15 of said ferrule of said drum.

 It can also be seen in FIG. 1 that said tank 7 which is mounted on feet or supports 27 advantageously comprises a drain or recirculation orifice 28 which makes it possible to remove from the inlet compartment 8 the impurities which have accumulated at the bottom of said inlet compartment, and this either punctually during a cleaning of said filter, or by a permanent circulation current which can for example represent from 5 to 10% of the volume of water treated by the device according to the invention .

 It can also be seen in FIG. 1 that in a particular embodiment, said inlet valve 35 allowing regulation of the inlet flow rate of the fluid to be filtered and allowing said inlet flow rate to be maintained within a predetermined range, comprises a body 34 of substantially vertical zzl axis, which body 34 is substantially cylindrical and in which can move a rod 32 linked to a disc-shaped valve 30, to an elastic membrane 33 linked to said body 34, which rod 32 extends to the 'outside of said body 34 in the upper part thereof so as to allow an adjustment of a restoring force exerted by. a return spring 29 situated outside said body and tending to return said rod 32 downwards, that is to say in a position where said valve 30 linked to said rod rests on a seat 31 insulating the lower and upper parts of said body 34 of said valve, which body is provided with an inlet orifice 36 through which the fluid can penetrate, and communicates with said inlet compartment 8 of said tank.

 With reference to FIG. 1, it can be seen that in the case where said inlet flow is located above the upper limit of a predetermined flow range, the imbalance of said rod 32 caused by the hydraulic forces exerted on said valve and said membrane and the mechanical forces caused by said return spring, tends to close said valve, that is to say to bring down said valve to a closed position which will tend to lower said inlet flow rate in said tank in order to bring it back into said predetermined range.

 Referring to Figure 2, we see that in the opposite case when said flow is located below a lower limit of a predetermined flow range, the result of mechanical and hydraulic forces on said rod 32 tends to lift said valve allowing the penetration or the increase of the flow of entry into said tank and thus making it possible to reduce said flow of entry into said tank into said range of predetermined flow.

 In Figure 3, there is illustrated a particular mode of use of a filtration device according to the invention in which two devices are connected in series to operate in cascade; we see that in this mode of use, said devices are vertically offset; in this case said respective axes xxl1 and xx12 of rotation of said drums 11 and 12 of the devices comprising respectively said tanks 71 and 72 are offset by a height H, which height H corresponds substantially to the difference in dimension between the axis of inlet of the inlet orifice into said first device (on the left in the figure) for example provided with said inlet flange 431, and the outlet axis of said device corresponding to the axis of the outlet orifice provided of said outlet flange 441.

 Thanks to this arrangement, it is possible to maintain the entry level 52 in the second device or downstream device at the same height as the exit level 61 of said first device, each of said devices placed in series comprising said partition 101,102 respectively separating said compartments. 'input and output of each of the devices; it can also be seen that each of said tanks 71 and 72 can be provided with said discharge or recycling orifice 281, 282.

 With reference to FIG. 4, it can be seen that the filtration device includes said means 35 for regulating the inlet flow rate making it possible to maintain the inlet flow rate within a predetermined range (on the right in FIG. 4), said tank 7 on which is fixed a device control box 45, as well as a motor 25 for driving said drum i by means of a speed reducer 263, a chain 262 and a toothed pulley 261; said motor 25 also drives a roller 40 for discharging said filter band 2 by means of said speed reducer 263, a chain 264 and a toothed pulley 265.

 It can be seen that advantageously a pressure roller 42 is provided which is parallel to said discharge roller and which serves to press said strip 2 to be discharged (having passed through said filter) against said discharge roller 40, said strip being thus pulled by said roller 40 said strip 2 unwinds from a supply reel or roller 39 on which it is wound, is guided by guide rollers 41 placed upstream of said drum 1, is then guided by said drum c ' ie by a lower part of its periphery, then by outlet guide rollers 412 up to said discharge roller 40 and pressure roller 42.

 This figure also shows said outlet orifice 44 of said tank and said discharge or recycling orifice 28 located in the lower part of said tank.

 In FIG. 5, it can be seen that in a particular embodiment, corresponding to the case where said filter strip is packaged on rollers without an axis or with a hollow axis 39, said roller on which said new filter strip is wound can be kept free in rotation while being held by a false shaft 47 which can rotate by means of a bearing with respect to a support 50 connected to said tank 7, which false shaft 47 acts as a point, which roller 39 with hollow shaft is held at its other end longitudinal by a tailstock or a second false shaft 48 which is advantageously mounted articulated with respect to an axis yy1 for example horizontal, which tailstock or false shaft 48 is also mounted on a bearing, the assembly being able to be pivoted by means of a handle 49 so as to disengage said hollow shaft from said roller or from said reel 39 for supplying clean canvas or clean strip.

 Also seen in this figure, said guide rollers 411 and 413 of said filter band located upstream of said drum 1, said flange 46 of said partition, which partition flange encircling said rear impermeable part of the shell of said drum (item 15) and comprises said seal ensuring the seal between said inlet and outlet compartments (marks 8 and 9 in FIG. i); it can also be seen in this figure that said drum is completely open on its rear face visible in FIG. 5 and that said impermeable rear part 15 of said ferrule 3 of said drum is held relative to said shaft mounted on said bearings 24, by said radial spacers 16.

 It can also be seen in this figure that said discharge roller 40 is also mounted by means of a tip and tailstock device which can be articulated, so as to release the strip which is kept pressed between said rollers 40 and 42 to facilitate the establishment of a new roll of said strip.

 In Figure 5, there is also illustrated said axis xxl of rotation of said drum as well as said outlet flange 44 of said device.

Claims (10)

 1. Wastewater filtration device characterized in that it comprises means for the gravity flow of said wastewater through a circulating filter band (2) for single use.  2. Device according to claim i characterized in that it comprises at least one drum (1) rotatable along a substantially horizontal axis (xxl) and at least one movable filter band (2) applied against a permeable external face (4) of the ferrule (3) of said drum, and characterized in that it comprises means for the gravity flow of said waste water from the outside of said drum towards the inside of said drum through said filter band.  3. Device according to claim 2 characterized in that said drum has a bottom (13) impermeable front in the form of a thin disc which seals a first end of said ferrule (3), which ferrule is open at its second end.  4. Device according to any one of claims 1 to 3 comprising means for controlling the rotation of said drum and therefore of the running speed of said filter band as a function of a level (5) of entry of said wastewater, which control means include a float level detector (20).  5. Device according to any one of claims 1 to 4 characterized in that it comprises at least one tank (7) comprising an inlet compartment (8) and an outlet compartment (9) separated by a partition (10 ) substantially vertical provided with a substantially circular opening (18) through which is arranged an impermeable zone (15) of said ferrule of said drum.  6. Device according to claim 5 characterized in that said opening of said partition is provided with a seal (19) in contact with the external face (15A) of said impermeable zone (15) of said ferrule.  7. Device according to any one of claims 1 to 6 characterized in that said drum is provided in said permeable zone (4) of said ferrule with a mesh (11), forming a support for said filter strip wound on a part at less than the external cylindrical surface of said ferrule.  8. Device according to any one of Claims 1 to 7, characterized in that the said means for maintaining the said inlet flow comprise a hydromechanical regulator (35) for the inlet flow comprising a movable shutter (30) and return means (29) of said shutter, and comprise means for easily accessible adjustment of the return force of said return means.  9. Device according to any one of claims 1 to 8 wherein two filters are used in series to ensure cascade filtration.  10. Device according to any one of claims 1 to 9 characterized in that the average filtration fineness of said filter strip (2) is less than 10-4 meters.