FR2846891A1 - Waste water filter comprises rectangular parallelepiped bag with base of lower porosity than side walls - Google Patents

Abstract

The filter consists of a rectangular parallelepiped bag with a lateral filtration surface and a base (3) that is less porous than its sides (2). The sides of the bag are made from mesh with holes less than 10 sq mm in area, and the base is of felt more than 5 mm thick or an impermeable material. The bag is surrounded by a fixed reinforcing surface (4) and its upper end has fastenings in the form of straps (5) for fixing it vertically within a supporting structure equipped with a receptacle for the filtered water. The volume of the receptacle is between 7 and 20 per cent of that of the bag, and it has a tap or pump to extract the filtered water from it.

Description

016,736-SPCBOO1

SERAZIN Pascal

  FILTERING AND CONDITIONING DEVICE FOR WASTEWATER WITH FILTER BAG

  The invention relates to the purification of waste water and in particular the filtration of waste water and storage

  residues extracted from wastewater.

  Many industries use large volumes of water. The resulting wastewater is frequently charged with solid particles or liquids most often having a viscosity or density different from that of water. Industrial processes thus generate large volumes of water loaded with impurities such as ink or oil. Wastewater, often very polluting, was previously discharged down the drain or into tributaries. Many laws then prohibited such discharge of wastewater. Some industrial painting processes use water flows to recover excess paint applied to parts. These processes generate large

  quantities of wastewater, difficult to store.

  Various devices and methods have been implemented for filtering waste water and discharging little polluted water, in particular in the field of industrial painting. According to a first method, a waste water loaded with paint in solution is placed in a tank. Flocculation products are then added to the water to form a purified water phase and a phase containing flocculated materials concentrated in paint. Phase 30 containing the flocculated materials is extracted from the tank and then placed in a bag held by a structure fixed in a workshop. This bag consists of a peripheral reinforcing fabric forming a square section tube and an inner felt covering fixed to the fabric and sealing one end of the tube and covering the interior surface of the tube. According to the method, the interior volume of the bag is filled with the phase containing the flocculated materials and the structure keeps the bag above a water recovery tank also fixed in the workshop. The felt filters the water in the bag for several hours. After several hours of filtration, the bag mainly comprises 5 flocculated materials, while the tank contains filtered water. However, this device and its associated method

  have drawbacks. This slowly filtering device is expensive, usable with a single manufacturing station and inconvenient to use.

  There is therefore a need, which the invention aims to satisfy, for a device comprising a bag for filtering waste water and for conditioning waste water residues, the bag having a duct having a lateral filtration surface, a bottom surface closing off one end of the duct, the bottom surface has a porosity less than the lateral filtration surface and the lateral filtration surface

presents a mesh.

  According to a variant, the mesh has a frame in which lights are produced, the ratio between the surface of the lights and the lateral filtration surface being between 0.25 and 0.80. It is also expected that the mesh has a frame in which are made lights comprising

surfaces less than 10 mM2.

  According to yet another variant, the bag also comprises a reinforcing surface fixed to and surrounding the surface of

lateral filtration.

  According to another variant, the bottom surface is made of felt. The felt has for example a thickness greater than 5 mm and a surface density greater than

grams / m2.

  According to yet another variant, the bottom surface 35 is impermeable.

  Provision is also made for the bag to further comprise at least one fixing member disposed at the end of the

  duct opposite the bottom surface.

  According to a variant, the bag comprises several fixing members, these fixing members being straps. According to yet another variant, the device further comprises a structure having: a recess in which the bag is housed vertically, said fixing member being arranged at the top and said bottom surface being arranged at the bottom; at least one fastening member on which at least one fixing member is fixed; -a filtered water receptacle located below the surface

  bottom of the bag and having a discharge pipe 15 for filtered water.

  According to another variant, the structure also has a grid arranged under the bottom surface of the bag and in the receptacle, the grid being capable of

  support the bottom surface when the bag is filled.

  According to yet another variant, the receptacle has a tank whose internal volume is between 7 and 20 percent of an internal volume of the bag delimited by the lateral filtration surface and the

bottom surface.

  provision is also made for the structure to further present a tap selectively closing the discharge conduit. According to a variant, the device further comprises a pumping system having an inlet inlet 30 for waste water, an outlet outlet for used water in the bag, an inlet inlet for water from the duct evacuation and a discharge outlet of the suction water. According to another variant, the pumping system 35 comprises a diaphragm pump and valve capable of sucking waste water from the suction inlet and

to push it back into the bag.

  According to yet another variant, the pump comprises a fixed body, and in that the valves of the diaphragm pump and valve are pivotally mounted relative to the fixed body. According to yet another variant, the pump has a

pneumatic drive.

  A device is also provided in which the valve and diaphragm pump has a first diaphragm 10 capable of sucking water from the waste water intake inlet and of discharging it into the discharge outlet, and a second membrane capable of sucking water from the water intake inlet of the evacuation duct and of discharging it into the discharge outlet of the aspirated water, the first and second membranes being integral. According to a variant, the passage area of the waste water suction inlet is greater than the passage area of the suction inlet

water from the drain.

  According to another variant, the pump is offset laterally relative to the bag. A device is also provided, further comprising a flocculation tank for waste water, the flocculation tank comprising in its upper part a tank for receiving flocculated materials, the opening of which is oriented upwards and the bottom of which communicates with the water inlet

worn out pumping system.

  According to yet another variant, the tank has a member

  for adjusting its height in the tank.

  According to yet another variant, the outlet for discharging used water into the bag comprises a pipe having a flattened end projecting into the bag and having a length of between 500 and 900 mm. The flattened end of the pipe may also have a distance of between 500 and 900 mm from the

bottom surface of the bag.

  It is expected that the structure will further comprise transparent lateral panels surrounding the bag, at least one of said panels pivoting relative to the rest of the structure, so as to allow the bag to be removed from the recess. According to a variant, the structure also has rollers on which it rests. According to yet another variant, the device has a height less than 2200 mm, and possibly a width and a depth less than 1200 and 1700 mm respectively. The invention will be better understood on reading the

  description which follows and upon examination of the figures which

  accompany it. The figures show: FIG. 1, a perspective view of an embodiment of a filtration and storage bag according to the invention; -Figure 2, a sectional view of the bag of Figure 1; FIG. 3, an enlarged representation of part of the lateral filtration surface of the bag of FIGS. 1 and 2; -Figure 4, an exploded perspective view of the main elements of a structure in which the bag of Figures 1 to 3 is placed; -Figure 5, a perspective view of the elements of the structure of Figure 4 after mounting and fixing a bag; -Figure 6, a schematic sectional view of a pump

  membrane and pivoting valve in a configuration of the prior art.

  -Figure 7, a schematic sectional view of a diaphragm pump and pivoting valve in a particular configuration, preferably used with the structure of Figures 4 and 5; -Figure 8, a principle view of the circulation of water in the device; FIG. 9, a view illustrating other elements of a device according to the invention; -Figure 10, a variant of the tank shown in

figure 9.

  The invention provides a device comprising at least one bag for filtering waste water and for storing residues extracted from waste water, comprising a duct provided with a lateral filtration surface having a mesh ensuring almost instantaneous filtration of '' waste water, 10 and a bottom surface intended to prevent drainage

  direct residue in filtered water.

  Figures 1 and 2 show a bag 1 according to a preferred embodiment of the invention. The bag includes a conduit formed from a lateral filtration surface. The lateral filtration surface is in this case formed by several panels 2. The lateral filtration surface has a mesh. A bottom surface 3 closes one end of the conduit. The bottom surface 3 has a porosity less than the porosity of the side surface. Thus, when used water is introduced or projected into the bag, the residues contained in the filtered water do not escape despite the higher water pressure in this zone. In particular, when the waste water contains flocculated materials, the probability of rupture of the flocculated materials by contact with the bottom surface is limited. The porosity of the lateral filtration surface being higher, this filters most of the waste water from the bag. The mesh makes it possible to evacuate the filtered water out of the bag with a consequent flow rate, while retaining the residues in the bag, and in particular the flocculated materials. It can therefore be considered that the use of this bag makes it possible to carry out almost instantaneous filtration of the waste water from the bag, and not decantation. The filtration time of a given volume of wastewater is in fact considerably reduced compared to the prior art. Thanks to the lateral mesh side filtration surface, and with higher porosity, the regular sedimentation of the residues on the bottom surface 3 has less effect on the total filtration time than in the prior art. Because the bag promotes the evacuation of filtered water, the bag also contains an optimized proportion of residue by volume. Since the bag also satisfactorily retains residues, it also functions

  residue storage packaging.

  In a preferred variant, the bag further comprises

  a reinforcing surface fixed to the lateral filtration surface and surrounding the lateral filtration surface.

  This reinforcing surface in this case comprises several panels 4. This surface is intended to guarantee the mechanical resistance of the bag, in particular in vertical traction. The reinforcing surface also makes it possible to prevent the water having passed through the lateral filtration surface from splashing around. The

  reinforcement surface thus allows water to run off.

  FIG. 3 represents a detail of the lateral filtration surface with a mesh. The filtration surface 20 comprises a frame 6 in which lights 7 are made. It is preferably provided that the ratio between the surface of the lights and the lateral filtration surface is greater than 0.25 in order to reduce the pressure drop of the water passing through the filtration surface. It is also preferably provided that this ratio is less than 0.8 in order to guarantee a sufficient mechanical resistance of the filtration surface, and in order to prevent most of the residues, in particular flocculated materials, from passing through the surface of 30 filtration. The skilled person will of course determine the

  optimal value depending on the type of waste water to be filtered.

  It is also possible to use lights comprising a unit area of less than 10 mM2, so as to keep the majority of the residues in the bag. It is possible in particular to provide a filtration surface having square lights of 1.7 mm side and a

  reinforcement with a mesh thickness of lmm.

  The bottom surface 3 is preferably made of felt. Thus, water trapped by sedimented residues can be filtered and discharged through the bottom surface 3. This increases the proportion of residues by volume in the bag. The filtration time of the waste water is also reduced, since this also gives an additional filtration surface. The felt optimally has a grammage greater than 50 grams per square meter, and a thickness greater than 10 5 mm. Any raw materials flocculated

  introduced also form a mat on the bottom surface 3, and cushion subsequent flocculated materials to prevent their breakage. The rupture of the flocculated materials can in fact facilitate their passage through the meshed filtration surface.

  It is also possible to use an impermeable bottom surface 3, in particular in order to increase the

mechanical resistance of the bag.

  As shown in Figures 1 and 2, the bag 20 further has at least one fixing member arranged

  at the end of the pipe opposite the bottom surface.

  The fixing member is preferably fixed to the reinforcing surface if necessary. In the example, the bag 1 has four straps 5, fixed by seams 8 to the reinforcing surface. The fastening device or the straps allow the bag to be suspended and kept deployed

  so that it can be filled optimally.

  Figures 4 and 5 show in perspective a structure preferably used with the bag described above. The structure 9 comprises a recess in which the bag 1 can be housed vertically. The bag 1 is logically arranged as shown in Figure 5, straps at the top and bottom surface at the bottom. The structure 9 also has at least one fastening member to which at least one bag fastening member is fixed. The structure in this case comprises four hooks 10 secured to an upper frame 11. The structure also has a receptacle for filtered water 12 disposed under the bottom surface 3 of the bag 1 and having a water discharge conduit filtered 13, disposed at the bottom of the receptacle. The receptacle 12 collects the water from the bag

and concentrates it in line 13.

  The recess of the structure 9 is provided in practice

  between four tubes 14 connecting the upper frame 11 and a lower frame 15. The tubes are inserted in particular in housings 17 of the upper frame. The lower frame of the example is intended to receive and support the receptacle of filtered water.

  The structure can also have a grid 18 arranged under the bottom surface of the bag and in the receptacle. Provision may be made for the grid to cover the entire upper opening of the receptacle. The grid 18 is provided to support the bottom surface when the bag

  is full. The grid 18 can thus reduce the stresses applied to the bottom surface 3, while allowing the passage of filtered water to the receptacle 12. The grid 18 can in particular take the form of a grating.

  A receptacle 12 is preferably used which has a tank whose internal volume is between 7 and 20 percent of the internal volume of the bag delimited by the lateral filtration surface and the bottom surface 3. This thus forms a buffer zone, which allows to store fluid when the evacuation of the filtered water is non-existent, for example during a pumping problem or during a movement of the device. In particular, the filtering of the contents of the bag can be allowed to end by interrupting a pumping of the contents of the receptacle, for example

  example when leaving a workshop where the device is used. According to a preferred variant, a tap 19 or a valve selectively closes the discharge conduit 13. The device can thus possibly be moved 35 while continuing to filter the water contained in the bag.

  As shown in Figure 5, the device may have a pumping system. The pumping system has a waste water suction inlet 20, a discharge outlet 21 in the bag 1 of the suction water used, a suction inlet 22 for the water in the discharge pipe and an outlet delivery 23 of the filtered filtered water. The pumping system ensures that the waste water to be filtered is pumped into the bag and the

  pumping filtered water from the bag.

  The pumping system preferably has a diaphragm pump and valve 24 capable of sucking waste water from the suction inlet 20 and of discharging it 10 into the bag. Such a pump makes it possible in particular to carry out an irregular pumping, which thus preserves the integrity of any flocculated materials of the waste water. Such a pump is furthermore particularly resistant for pumping waste water loaded with impurities such as paint, iron filings or any other residue. The maintenance of such a pump is also easy, since its disassembly is facilitated. Preferably, a pump 24 is used as illustrated in FIGS. 6 or 7. The pump 24 has a fixed pump body, possibly made of several integral sub-assemblies. Valves 26 are pivotally mounted with respect to the fixed body 25 for selectively blocking the passage of fluid between an inlet, a pumping space by the membrane, and an outlet. These pivoting valves 26 thus selectively come into contact with the seats 27 to close the passage of fluid. Such an arrangement makes it possible to provide a large passage section in the open position, in a reduced volume. It is thus possible to provide a passage section at the level of the valve of approximately 50 mm in diameter. Such a section makes it possible to pump waste water containing pieces of dried paint or hardened flocculated materials without blocking the valves. The pump 24 is thus not very sensitive to the quality of the waste water. Preferably, a pneumatic drive pump is used, usable in environments with

  flammable gases, for example areas classified ADF.

  Figure 6 shows a pump configuration according to the prior art, while Figure 7 shows a preferred pump configuration 24 in the context of the invention. Unlike the conventional use of such a pump, illustrated in FIG. 6, it is preferably sought to provide discontinuous pumping 5 in the device of the invention. The same pump is thus used to pump the waste water and pump the filtered water in FIG. 7. The two membranes 28 and 29 are thus integral and carry out pumping in respective cavities 30 and 31. The first membrane 28 sucks water from the waste water inlet 20 and discharges it into the outlet 21 due to the arrangement of the valves 26. The second membrane 29 sucks the filtered water from the inlet 22 and the delivers at outlet 23. The same pump is thus used to carry out two pumps. For a bag with a cubic shape having a side of 1000 mm, for example, a pump having a pumping capacity of

  the inlet 20 of about 200 liters per minute.

  According to a variant, the passage area of the inlet 20 is greater than the passage area of the inlet 22. In fact, the flow rate of filtered water coming from the bag is less than the flow rate of waste water introduced in the bag about 10 to 20% in most cases, due to the retention of residues in the bag. By reducing the pumping capacity of the filtered water, the service life of the pump is increased by preventing the pumping of the filtered water from pumping a

excess air.

  According to the configuration illustrated in Figure 5, the pump 24 is offset laterally relative to the bag. The structure can thus have a reduced height, in order to allow the device to be moved in a workshop. It is preferable to use a device having a height of less than 2200mm in order to allow it to pass through most door frames. 35 The structure can thus have a pump support 32, which is fixed laterally on beams of the lower frame 15 by means of hooks 33. According to an additional variant, the structure rests on casters 34, which in particular make it possible to move the device 1 in a workshop. It is thus possible to plan to use the same device for several work stations generating waste water. It is possible in particular to provide a storage tank 35 for each work station, to which the device 1 is periodically connected in order to filter the stored waste water. We can plan to connect the

  device with a filtered water storage tank 36.

  The discharge outlet 21 may comprise a tube 37 10 connected in the pumping system, opening into the upper part of the bag, as shown in FIGS. 4, 5, 8 and 9. The discharge outlet 21 may also have at its end a flexible pipe 38, connected for example to the end of the tube 37. The pipe 38 15 preferably has a flattened end projecting into the bag 1. The flattened end makes it possible to slow down the used water before it is projected into the bag so not to break any flocculated material. The flexible hose preferably has a length between 500 and 900mm, in order to allow a

  pivoting distributing the waste water residues in the bag and allowing a good slowdown of the waste water.

  The pivoting of the pipe is illustrated in Figure 9 by the double arrow line. The pivoting is favored by the use of the valve and diaphragm pump whose flow is irregular. Provision may also be made for the flattened end of the pipe 38 to have a distance of between 500 and 900 mm from the surface of the bottom of the bag 3 in order to limit the rupture of flocculated materials 30 projected into the bag. One can plan to combine a pipe 38 with a tube 37 pivoting relative to the rest of the structure relative to its axis, in order to favor

  the insertion or extraction of the bag 1 from the structure.

  Figures 9 and 10 illustrate the use of a flocculation tank 35 with the device. This flocculation tank receives waste water, for example from a painting station in a workshop. The wastewater is separated into two phases: a low-polluted water phase 40, generally occupying the bottom of the tank 35, and a flocculated material phase 39, in the form of quasi-solid amalgams concentrated in residues and bathing in water. A tank for receiving flocculated materials is then placed in the upper part of the flocculation tank 35. The opening of the tank is oriented upwards so as to recover flocculated materials. The bottom of the tank communicates with the waste water inlet 20 of the pumping system via a conduit 42. According to the preferred variant shown in FIG. 10, the tank is provided with an adjustment member for its height in the tank. The tank in this case has two through grooves 43 into which threaded rods 44 are inserted, integral with the tank 35. Nuts then selectively press the tank against the tank 35. The tank 41 is then moved and selectively fixed relative to the tank so that the edge of the tank still receives flocculated material when the

wastewater level varies.

  The structure may further include transparent side panels surrounding the bag and not shown. These panels help prevent water splashing out of the structure while monitoring possible filtering problems. It is expected that at least one panel will pivot relative to the rest of the structure in order to allow insertion or extraction.

from the bag.

  The invention is of course not limited to the examples and embodiments described and shown, but is capable of numerous variants accessible to those skilled in the art. So, although the figures represent a square section bag, we can consider

  any other suitable type of section.

Claims (27)

  1. Device comprising a bag for filtering (1) waste water and for conditioning waste water residues, the bag having: -a duct having a lateral filtration surface (2), -a bottom surface (3 ) sealing one end of the conduit; characterized in that the bottom surface (3) has a porosity less than the lateral filtration surface and the lateral filtration surface has a mesh. 15 2. Device according to claim 1, characterized in that the mesh has a frame (6) in which lights (7) are produced, characterized in that the ratio between the surface of the lights and the lateral filtration surface is understood Between 0.25 and 0.80.   3. Device according to claim i or 2, characterized in that the mesh has an armature in which lights are made, characterized in that the lights include surfaces less than 10 mM2.   4. Device according to any one of the preceding claims, characterized in that the bag comprises in   in addition to a reinforcement surface (4) fixed to and surrounding the lateral filtration surface.   5. Device according to any one of the preceding claims, characterized in that the bottom surface (3) is made of felt.   6. Device according to claim 5, characterized in that the felt has a thickness greater than 5 mm   and a surface density greater than 50 grams / m2.   7. Device according to any one of claims 1   to 4, characterized in that the bottom surface is impermeable.   8. Device according to any one of claims   previous, characterized in that the bag further comprises at least one fixing member (5) arranged at   the end of the pipe opposite the bottom surface.   9. Device according to claim 8, characterized in that it comprises several fixing members, these   fixing members being straps (5).   10. Device according to claim 8 or 9, characterized in that it further comprises a structure having: a recess in which the bag is housed vertically, said fixing member being disposed at the top and said bottom surface being arranged at the bottom; at least one fastening member (10) on which at least one fixing member (5) is fixed;   a filtered water receptacle (12) disposed under the bottom surface of the bag and having a discharge pipe (13) for filtered water.   11. Device according to claim 10, characterized in that the structure also has a grid (18) arranged under the bottom surface of the bag and in the receptacle, the grid being capable of supporting   the bottom surface when the bag is filled.   12. Device according to claim 10 or 11, characterized in that the receptacle has a tank whose internal volume is between 7 and 20 5 percent of an interior volume of the bag delimited by the lateral filtration surface and the surface of background. 13. Device according to claim 12, characterized in 10 that the structure also has a tap (19)   selectively closing the exhaust duct (13).   14. Device according to any one of claims   to 13, characterized in that it further comprises a pumping system having a suction inlet   waste water (20), a discharge outlet for the waste water in the bag (21), a water intake inlet for the discharge conduit (22) and a discharge outlet for the water sucked into the discharge conduit 20 (23).   15. Device according to claim 14, characterized in that the pumping system comprises a diaphragm pump and valve (24) capable of sucking waste water from the suction inlet (20) and the return to the bag (1).   16. Device according to claim 15, characterized in that the pump comprises a fixed body (25), and in that the valves (26) of the diaphragm pump and valve   are pivotally mounted relative to the fixed body (25).   17. Device according to claim 15 or 16,   characterized in that the pump has a pneumatic drive.   18. Device according to any one of claims   to 17, characterized in that the valve and diaphragm pump has a first diaphragm (28) capable of sucking water from the waste water intake inlet 5 and of discharging it into the discharge outlet , and a second membrane (29) capable of sucking water from the water suction inlet of the evacuation duct and of discharging it into the discharge outlet of the water sucked in, the first and second membranes being integral. 19. Device according to claim 18, characterized in that the passage area of the waste water intake inlet is greater than the area of passage of the water intake inlet of the conduit. discharge.   20. Device according to any one of claims 20 15 to 19, characterized in that the pump (24) is   laterally offset from the bag.   21. Device according to any one of the claims   14 to 20, characterized in that it further comprises a waste water flocculation tank (35), the   flocculation comprising in its upper part a receiving tank (41) of flocculated materials (39), the opening of which is oriented upwards and the bottom of which communicates with the waste water intake inlet of the pumping system.   22. Device according to claim 21, characterized in that the tank has an adjustment member (43) of its height in the tank.   23. Device according to any one of claims   to 22, characterized in that the outlet for discharging the used water into the bag comprises a pipe having a flat end projecting 5 into the bag and having a length between 500 and 900 mm.   24. Device according to claim 23, characterized in that the flattened end of the pipe has a distance of between 500 and 900 mm from the bottom surface of the bag.   25. Device according to any one of claims   to 24, characterized in that the structure further comprises transparent lateral panels surrounding the bag, at least one of said panels pivoting relative to the rest of the structure, so as to allow to take the bag out of the recess.   26. Device according to any one of claims   to 25, characterized in that the structure has   further castors on which it rests.   27. Device according to claim 26, characterized in that the device has a height less than 2200 mm, and possibly a width and a depth less than 1200 and 1700 mm respectively.