Filtration Equipment

Abstract

This filter device 10 includes: a first electrode 31 provided with a plurality of first openings 31b; a second electrode 32 provided with a plurality of second openings 32b and provided facing one surface of the first electrode 31; a filter material 34 provided with a plurality of apertures and provided between the first electrode 31 and the second electrode 32; a filter chamber provided in contact with the other surface of the first electrode 31 and supplied with a liquid to be processed that includes particles to be separated and a liquid; and a third electrode 33 that faces the first electrode 31 with the filter chamber interposed therebetween. The first electrode 31 and the second electrode 32 that sandwich the filter material 34, or the third electrode 33 are able to move in the facing direction in which the first electrode and the third electrode face each other.

Description

[Technical field]

[0001] The present disclosure relates to a filtration device. [Background technology]

[0002] A compression type filter has been used conventionally as a filter for filtering a slurry. As shown in the following patent document, in a conventional compression type filter, a filter medium such as a filter cloth is placed at the bottom of a vessel. Slurry is piled up on the filter medium. A pressure plate is placed above the slurry. When the pressure plate descends, the slurry is pressed against the filter medium. The liquid contained in the slurry passes through the filter medium and is discharged outside the vessel. On the other hand, solids do not pass through the filter medium, and a dehydrated cake is produced on the filter medium. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 56-001796 Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional compression-type filtration devices, particles contained in the slurry block the filter media, causing clogging of the filter media, which results in a decrease in filtration speed and a long filtration process time.

[0005] In view of the above problems, an object of the present disclosure is to provide a filtration device that shortens the time required for filtration processing. [Means for solving the problem]

[0006] The filtration device according to a first aspect of the present disclosure includes a first electrode having a plurality of first openings, a second electrode having a plurality of second openings and disposed opposite one surface of the first electrode, a filter medium having a plurality of meshes and disposed between the first electrode and the second electrode, a filter chamber disposed in contact with the other surface of the first electrode and to which a target processing liquid containing particles to be separated and a liquid is supplied, and a third electrode disposed opposite the first electrode across the filter chamber. The first electrode and the second electrode, or the third electrode, which sandwich the filter medium, are movable in a direction in which the first electrode and the third electrode face each other. Effect of the Invention

[0007] According to the filtration device of the present disclosure, the filtration process time is shortened. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view that illustrates a configuration example of a filtering device according to a first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view showing the filtration device according to the first embodiment during filtration (compression). [Diagram 3] FIG. 3 is an explanatory diagram for explaining the operation of the filtering device according to the first embodiment. [Figure 4] FIG. 4 is a cross-sectional view that illustrates the configuration of the first electrode, the filter medium, and the second electrode. [Diagram 5] FIG. 5 is an electrical equivalent circuit diagram showing the filtering device according to the first embodiment. [Figure 6] FIG. 6 is a flow diagram showing a usage state of the filtering device according to the first embodiment. [Figure 7] FIG. 7 is a cross-sectional view that illustrates a configuration example of a filtering device according to the second embodiment. [Figure 8] FIG. 8 is an explanatory diagram for explaining the operation of the filtering device according to the second embodiment. [Figure 9] FIG. 9 is an electrical equivalent circuit diagram showing the filtering device according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the following modes for carrying out the invention (hereinafter, referred to as embodiments). Furthermore, the components in the following embodiments include those that a person skilled in the art can easily imagine, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the components disclosed in the following embodiments can be appropriately combined.

[0010] (Embodiment 1) FIG. 1 is a cross-sectional view showing a schematic configuration example of a filtration device according to the first embodiment. The filtration device 10 according to the first embodiment is a device for separating particles 71 from a slurry (raw liquid) 70 (a target treatment liquid) in which particles (particles to be separated) 71 are dispersed in a polar solvent 72. Specifically, the filtration device 10 can be applied to the fields of life science, sewage treatment, and wastewater treatment. In the field of life science, the filtration device 10 can be applied to the bioindustry for culturing microbial bodies such as cultured cells, microalgae, bacteria, and viruses, the biopharmaceutical drug discovery and cosmetics industry, which are fields of application and utilization of enzymes, proteins, polysaccharides, lipids, and the like produced extracorporeally and intracorporeally by cultured microbial bodies, and the beverage industry for handling brewing, fermentation, juicing, beverages, and the like. In the fields of sewage treatment and wastewater treatment, the filtration device 10 can be applied to the separation of biomass fine particles from a fine biomass aqueous slurry that is difficult to filter. Alternatively, the filtration device 10 can be applied to the concentration and recovery of colloidal fine particles from a colloidal fine particle-based slurry in which surface-charged fine particles are highly dispersed by an electric repulsive action.

[0011] As shown in Fig. 1, the filtration device 10 according to the first embodiment includes an upper housing 11, a cover 12, a side housing 13, a lower housing 14, a conductor 15, and a cylinder (not shown). The filtration device 10 includes a first filtration chamber 30, a first electrode 31, a second electrode 32, a third electrode 33, and a filter medium 34 (see Fig. 3) in an internal space surrounded by the upper housing 11, the side housing 13, and the lower housing 14. A first power source 51 and a second power source 52 are electrically connected to the filtration device 10. The first electrode 31, the second electrode 32, the third electrode 33, and the filter medium 34 are arranged in the up-down direction.

[0012] The upper housing 11 is a cylindrical member made of an insulating material. The side housing 13 is an annular member made of an insulating material and has a through hole 13a. The lower end of the upper housing 11 is inserted into the through hole 13a of the side housing 13. The lower end of the upper housing 11 is also slidably fitted into the inner circumferential surface of the through hole 13a. Therefore, the upper housing 11 is slidable in the up and down direction relative to the side housing 13. The lid 12 is disposed above the upper housing 11 and is integrated with the upper housing 11.

[0013] A connecting part 60 that connects to a shaft part of a cylinder (not shown) is connected to the upper part of the lid part 12. Examples of the cylinder include an air cylinder and a hydraulic cylinder. Therefore, when the cylinder is driven, the lid part 12 and the side housing 13 move up and down via the connecting part 60. This changes the volume of the first filter chamber 30. The lower housing 14 is formed of an insulating material and supports the side housing 13. The lid part 12 is provided to cover the upper surface of the upper housing 11. Note that, although the embodiment includes a cylinder and a connecting part 60, the present disclosure does not necessarily include the cylinder and the connecting part 60. In such a case, it is necessary for an operator to work to move the upper housing 11 in the vertical direction.

[0014] The outer edges of the first electrode 31, the second electrode 32, and the filter material 34 (see FIG. 3) are sandwiched and fixed between the side housing 13 and the lower housing 14. The third electrode 33 is disposed inside the through hole of the side housing 13. The third electrode 33 is fixed to the lower surface of the upper housing 11 (the surface facing the lower housing 14) by a fastener such as a bolt. Therefore, when the upper housing 11 moves up and down by driving the cylinder, the third electrode 33 also moves up and down. The first electrode 31 and the third electrode 33 face each other in the vertical direction. The conductor 15 is an annular member provided so as to surround the periphery of the side housing 13, and is provided between the side housing 13 and the lower housing 14. The lower end side of the conductor 15 is connected to the outer edge of the first electrode 31. The upper housing 11 and the conductor 15 are annular members, but are not limited thereto, and may be other shapes such as a polygonal shape.

[0015] The upper housing 11 and the side housing 13 are connected by the guide portion 21a so as to be slidable (movable) in the vertical direction. As a result, the upper housing 11 is supported by the side housing 13 without any rattling in a plane perpendicular to the guide portion 21a. The side housing 13, the lower housing 14, and the conductor 15 are fixed by the bolts 21b and 21c. As a result, the positions of the housings are fixed, and a first filter chamber 30 is formed in a space surrounded by the first electrode 31, the second electrode 32, the filter material 34, the inner wall of the side housing 13, and the third electrode 33. In addition, sealing members such as O-rings are provided at the connection parts between the housings and between the electrodes, and the first filter chamber 30 is provided in a sealed manner. In addition, the distance between the upper housing 11 and the lower housing 14 is adjusted by driving the cylinder. This allows the filtration device 10 to appropriately set the volume of the first filtration chamber 30 according to the type and amount of the slurry (raw liquid) 70 (hereinafter, also referred to as the target liquid to be treated).

[0016] The upper housing 11 is provided with a slurry supply passage 11a, an exhaust passage 11b, and a through hole 11c. One end of the slurry supply passage 11a opens to a side surface of the upper housing 11 and is connected to a slurry supply unit 16. The other end of the slurry supply passage 11a opens to a lower surface of the upper housing 11 and is connected to a through hole 33a of the third electrode 33. The slurry supply valve 17 has a rod-shaped member 17a provided inside the slurry supply passage 11a, and the rod-shaped member 17a moves vertically inside the slurry supply passage 11a to switch between an open and closed state of the through hole 33a.

[0017] As a result, for example, when the through-hole 33a is opened by the operation of the slurry supply valve 17, the slurry (undiluted liquid) 70 is supplied to the first filtration chamber 30 via the slurry supply part 16, the slurry supply passage 11a, and the through-hole 33a of the third electrode 33. On the other hand, when the through-hole 33a is closed by the slurry supply valve 17, the supply of the slurry (undiluted liquid) 70 to the first filtration chamber 30 is stopped.

[0018] One end of exhaust passage 11b opens to a side surface of upper housing 11 and is connected to air discharge unit 18. The other end of exhaust passage 11b opens to a bottom surface of upper housing 11 and is connected to through hole 33b of third electrode 33. Air discharge valve 19 has a rod-shaped member 19a provided inside exhaust passage 11b, and rod-shaped member 19a moves up and down inside exhaust passage 11b and its tip is inserted into and removed from through hole 33b, thereby switching between an open and closed state of through hole 33b.

[0019] The slurry supply valve 17 and the air exhaust valve 19 are fixed to the lid 12. Therefore, when the cylinder is driven, the slurry supply valve 17 and the air exhaust valve 19 move up and down together with the lid 12 and the side housing 13.

[0020] When the slurry (raw material) 70 is supplied to the first filtration chamber 30, the air discharge valve 19 opens the through hole 33b. As a result, the air in the first filtration chamber 30 is discharged to the outside through the through hole 33b, the exhaust passage 11b, and the air discharge part 18. An air discharge valve 18a is connected to the air discharge part 18. The air discharge valve 18a is, for example, a float valve, and is provided so that the air discharge valve 18a closes when a predetermined amount of air in the first filtration chamber 30 is discharged. After the exhaust of the first filtration chamber 30 is completed, the air discharge valve 19 closes the through hole 33b.

[0021] One end of the through hole 11c opens to the top surface of the upper housing 11. The other end of the through hole 11c opens to the bottom surface of the upper housing 11 and is connected to the recess 33c of the third electrode 33. A connection conductor 56 is inserted into the through hole 11c, and the connection conductor 56 and the third electrode 33 are connected at the recess 33c. As a result, the third electrode 33 is electrically connected to the reference potential GND via the connection conductor 56. The reference potential GND is, for example, a ground potential. However, the reference potential GND is not limited to this, and may be a predetermined fixed potential different from the ground potential.

[0022] The first electrode 31 is electrically connected to a second terminal 51b of the first power source 51 via the conductor 15 and a connecting conductor 54. In addition, the first electrode 31 is electrically connected to a first terminal 52a of the second power source 52 via the conductor 15 and a connecting conductor 55a.

[0023] The lower housing 14 is provided with a concave second filter chamber 35, through holes 14a and 14b, and a connection hole 14c. The second filter chamber 35 is provided at a position overlapping the first filter chamber 30 on the upper surface of the lower housing 14. The through hole 14a connects the second filter chamber 35 to the discharge section 22. The slurry (raw liquid) 70 supplied to the first filter chamber 30 is separated into particles 71 by driving each electrode, and the polar solvent 72 (filtrate 75) from which the particles 71 have been separated passes through the first electrode 31, the filter material 34 (see FIG. 3), and the second electrode 32 and flows into the second filter chamber 35. The filtrate 75 containing the polar solvent 72 from which the particles 71 have been separated is stored in an external storage tank from the discharge section 22 of the second filter chamber 35 via the through hole 14b.

[0024] One end of the connection hole 14c opens to the top surface of the lower housing 14, and the outer edge of the second electrode 32 is provided to cover the opening 14d of the connection hole 14c. The other end of the connection hole 14c opens to the side surface of the lower housing 14. A connection conductor 55b is inserted into the connection hole 14c, and the connection conductor 55b and the second electrode 32 are connected. As a result, the second electrode 32 is electrically connected to the second terminal 52b of the second power source 52.

[0025] 1 is merely an example, and any configuration may be used as long as it can form the first filter chamber 30 sandwiched between the first electrode 31, the second electrode 32, and the filter medium 34 (see FIG. 3) and the third electrode 33. The first electrode 31, the second electrode 32, and the third electrode 33 may be made of, for example, a titanium alloy or an anodized aluminum alloy, but are not limited thereto.

[0026] FIG. 2 is a cross-sectional view showing the filtering device according to the first embodiment during filtering (squeezing). The filtering process of the filtering device 10 described above will be briefly described. During filtering process of the filtering device 10, as shown in FIG. 2, the through-hole 33a and the through-hole 33b of the third electrode 33 are closed by inserting the rod-shaped member 17a and the rod-shaped member 19a. The cylinder (not shown) is driven, and the cover 12 and the side housing 13 move downward (see the arrow X). That is, the third electrode 33 presses the slurry 70 supplied to the first filtering chamber 30 downward. As a result, the slurry 70 is pressed (squeezed) against the first electrode 31, the second electrode 32, and the filtering material 34. Then, the liquid contained in the slurry 70 passes through the filtering material 34 and moves to the second filtering chamber 35, and is discharged from the discharge part 22. On the other hand, particles contained in the slurry 70 having a particle size larger than the mesh openings 34b (see FIG. 3) of the filter medium 34 cannot pass through the filter medium 34 and are deposited on the filter medium 34 as a dehydrated cake 80. Hereinafter, pressing the slurry 70 against the first electrode 31, the second electrode 32, and the filter medium 34 by the third electrode 33 may be simply referred to as "squeezing."

[0027] In addition, in order to avoid an increase in the filtration resistance of the filter medium 34, the filtration device 10 of the first embodiment squeezes the filter medium 34 while supplying a predetermined potential to the first electrode 31, the second electrode 32, and the third electrode 33 from the first power source 51 and the second power source 52. Hereinafter, the filtration device 10 will be described in detail with reference to Figs. 3 to 5.

[0028] Fig. 3 is an explanatory diagram for explaining the operation of the filtration device according to embodiment 1. In Fig. 3, for ease of understanding, the positional relationship between the first electrode 31, the second electrode 32, the third electrode 33, and the filter medium 34, and the first filter chamber 30 and the second filter chamber 35 is shown typically.

[0029] As shown in FIG. 3, the first electrode 31 and the second electrode 32 are, for example, mesh-like electrodes having openings. Specifically, the first electrode 31 has a plurality of conductive fine wires 31a, and a plurality of first openings 31b are provided between the plurality of conductive fine wires 31a. The second electrode 32 has a plurality of conductive fine wires 32a, and a plurality of second openings 32b are provided between the plurality of conductive fine wires 32a. The second electrode 32 is provided facing one surface (lower surface) of the first electrode 31 through the filter material 34. In other words, the filter material 34 is provided between the first electrode 31 and the second electrode 32. The first electrode 31 and the second electrode 32 are provided in direct contact with the filter material 34. The plurality of conductive fine wires 31a and the plurality of conductive fine wires 32a may be metal or carbon fiber. The first electrode 31 and the second electrode 32 are not limited to a configuration in which they are in direct contact with the filter material 34, and may be arranged with a gap between them.

[0030] The filter medium 34 is formed by providing a plurality of openings 34b in a filtration membrane 34a. For example, a microfiltration membrane (MF membrane), an ultrafiltration membrane (UF membrane), or the like is used as the filter medium 34. In the first embodiment, the filter medium 34 is formed of an insulating material such as a resin material. Note that, in FIG. 3, the first opening 31b of the first electrode 31, the second opening 32b of the second electrode 32, and the openings 34b of the filter medium 34 are shown to have the same size, but this is merely a schematic illustration for the purpose of explanation, and the sizes of the first opening 31b, the second opening 32b, and the openings 34b may be different.

[0031] FIG. 4 is a cross-sectional view showing the configuration of the first electrode, the filter medium, and the second electrode. As shown in FIG. 4, the diameter D3 of the openings 34b provided in the filter medium 34 is smaller than the diameter D1 of the first opening 31b of the first electrode 31, and smaller than the diameter D2 of the second opening 32b of the second electrode 32. In other words, the arrangement pitch of the multiple conductive fine wires 31a, the arrangement pitch of the multiple conductive fine wires 32a, and the arrangement pitch of the filtration membrane 34a are different from each other. For example, the diameter D1 of the first opening 31b of the first electrode 31 is 0.5 μm or more and 500 μm or less, for example, about 70 μm. The diameter D2 of the second opening 32b of the second electrode 32 is 0.5 μm or more and 1000 μm or less, for example, about 100 μm. The diameter D3 of the plurality of openings 34b provided in the filter medium 34 is about 0.1 μm or more and 100 μm or less, and more preferably about 1 μm or more and 7 μm or less.

[0032] Moreover, the diameter D1 of the first opening 31b of the first electrode 31 is smaller than the diameter D2 of the second opening 32b of the second electrode 32. However, without being limited thereto, the diameter D1 of the first opening 31b of the first electrode 31 may be formed to be the same size as the diameter D2 of the second opening 32b of the second electrode 32. With this configuration, the openings 34b of the filter medium 34 are provided so as not to overlap with the multiple conductive fine wires 31a and the multiple conductive fine wires 32a at least in the region overlapping with the first opening 31b and the second opening 32b. Moreover, the distance between the first electrode 31 and the second electrode 32 is determined by the thickness of the filter medium 34.

[0033] Returning to Fig. 3, the third electrode 33 is a plate-shaped member, and is provided facing the other surface (upper surface) of the first electrode 31 across the first filter chamber 30. Note that the through holes 33a, 33b and the recessed portion 33c (see Fig. 1) of the third electrode 33 are omitted in Fig. 3.

[0034] The first filter chamber 30 is provided in contact with the other surface (upper surface) of the first electrode 31. As described above, a slurry (raw liquid) 70 containing particles 71 to be separated and a polar solvent 72 is supplied to the first filter chamber 30. The particles 71 are, for example, biomass fine particles or colloidal fine particles, and the particle surfaces are negatively charged. Specifically, the particles 71 are chlorella, microalgae spirulina, colloidal silica, Escherichia coli, sewage activated sludge, etc. The diameter of the particles 71 varies depending on the applied technical field and the type of separation target, but is about 5 nm to 2000 μm, for example, 20 nm to 500 μm.

[0035] The polar solvent 72 in which the particles 71 are dispersed is water, and the water molecules 73 are positively charged. As a result, the slurry (undiluted liquid) 70 is in an electrically balanced state as a whole. The polar solvent 72 is not limited to water, and may be, for example, alcohol. In other words, the polar solvent 72 may be any polar solvent.

[0036] During filtering (compressing) of the filtration device 10, the first power source 51 supplies the first electrode 31 with a first potential V1 having the same polarity as the polarity of the particles 71. The first potential V1 is, for example, -60V. The second power source 52 supplies the second electrode 32 with a second potential V2 having the same polarity as the polarity of the particles 71 and an absolute value greater than the absolute value of the first potential V1. The second potential V2 is, for example, -70V. The third electrode 33 is connected to the reference potential GND. The reference potential GND is a ground potential as described above, and is ideally 0V. Note that the reference potential GND supplied to the third electrode 33 is not limited to 0V, and may be a predetermined fixed potential. The first potential V1 and the second potential V2 can be set in the range of 1mV to 1000V in absolute value.

[0037] Fig. 5 is an electrical equivalent circuit diagram showing the filtration device according to the first embodiment. As shown in Fig. 5, the first power source 51 is a constant voltage source, and the second power source 52 is a constant current source. A resistance component R1 and a capacitance component C are connected in parallel between the first electrode 31 and the second electrode 32. The resistance component R1 and the capacitance component C are components equivalently represented by the filter medium 34 having a large number of openings 34b. In addition, a resistance component R2 is connected between the first electrode 31 and the third electrode 33. The resistance component R2 is a resistance component equivalently represented by the slurry (raw liquid) 70 in the first filter chamber 30.

[0038] The second power source 52 may be a constant voltage power source or a constant current power source. In the first embodiment, the second power source 52 is a constant current source, so the second potential V2 changes according to the filtering state of the filtering device 10, that is, according to fluctuations in the resistance component R1 of the filtering medium 34 and the resistance component R2 of the first filtering chamber 30. However, the second potential V2 has the same polarity as that of the particles 71, and maintains a value greater than the absolute value of the first potential V1.

[0039] Next, the action and effect of each electrode (31, 32, 33) during filtration (compression) by the filtration device 10 will be described. As shown in Fig. 3, during compression by the filtration device 10, a repulsive force F1 is generated between the negatively charged particle 71 and the first electrode 31. That is, the negatively charged particle 71 moves away from the first electrode 31 and approaches the third electrode 33 due to the repulsive force F1 generated between the negatively charged particle 71 and the first electrode 31.

[0040] Therefore, during squeezing by the filtration device 10, the slurry 70 itself is pressed against the first electrode 31 and the filter medium 34, but the particles 71 inside the slurry 70 are distributed closer to the third electrode 33. This prevents the particles 71 from clogging the openings 34b of the filter medium 34. As the water contained in the slurry 70 decreases due to squeezing, the distance between the first electrode 31 and the particles 71 decreases. Then, toward the end of squeezing, the particles 71 come into contact with the filter medium 34. Finally, the particles 71 contained in the slurry 70 are layered on the first electrode 31 and the filter medium 34 to form a dehydrated cake 80.

[0041] Additionally, an attractive force is generated between the positively charged water molecules 73 and the first electrode 31. The attractive force F2 acting on the positively charged water molecules 73 acts in the direction indicated by the arrow, that is, in the direction from the third electrode 33 toward the first electrode 31. The positively charged water molecules 73 move toward the first electrode 31. At this time, due to the potential difference between the first electrode 31 and the second electrode 32, a barrier electric field E (indicated by a dashed line in FIG. 3) is formed from the first electrode 31 toward the second electrode 32 so as to penetrate the filter medium 34 in the thickness direction.

[0042] The water molecules 73 that have moved to the first electrode 31 side are subjected to a force by the electric field E and are pulled to the second electrode 32 side and pass through the filter medium 34. As the water molecules 73 move, the surrounding water molecules 73 are also pulled to the second electrode 32 side, generating an electroosmotic flow. As a result, the polar solvent 72 (filtrate 75) containing the positively charged water molecules 73 flows into the second filter chamber 35. Therefore, the amount of water discharged per unit time (the amount of water moving to the second filter chamber 35) increases compared to the case of simple filtration.

[0043] From the above, according to the filtration device 10 of the first embodiment, the particles 71 do not come into contact with the filter medium 34 from the start of filtration until the end of squeezing, so the filtration resistance of the filter medium 34 does not increase. In other words, the filtration rate of the filter medium 34 is maintained at a high state (unclogged state) for a long time, and the filtration process time is shortened. In addition, since the amount of water discharged per unit time (the amount of water moving to the second filter chamber 35) is increased, the filtration process (squeezing process) time is further shortened. In addition, the particles 71 are subjected to a repulsive force from the first electrode 31 and are distributed closer to the third electrode 33. Therefore, filtration leakage (particles 71 passing through the mesh openings 34b of the filter medium 34) is avoided.

[0044] In addition, the filtering device 10 of the first embodiment may be configured to control the level of particles (particle diameter) passing through the filter medium 34 by controlling the electric field formed between the first electrode 31 and the second electrode 32. For example, by applying a first potential V1=-60V to the first electrode 31 and a second potential V2=-70V to the second electrode 32, a barrier electric field E (see FIG. 3) is formed between the first electrode 31 and the second electrode 32, and particles 71 having a diameter smaller than the mesh openings 34b of the filter medium 34 can be prevented from passing through the filter medium 34. That is, according to this embodiment, nanoparticles can also be compressed.

[0045] That is, even when a filter medium 34 equivalent to a microfiltration membrane (MF membrane) is used, the particle size of the separation target can be changed to that of an ultrafiltration membrane (UF membrane) or nanofiltration membrane (NF membrane) by controlling the electric field between each electrode at the first power source 51, the second power source 52, and the reference potential GND. The ultrafiltration membrane (UF membrane) is a filtration membrane with an opening diameter of about 10 nm or more and 100 nm or less. The nanofiltration membrane (NF membrane) is a filtration membrane with an opening diameter of about 1 nm or more and 10 nm or less.

[0046] FIG. 6 is a flow diagram showing the use state of the filtration device according to the first embodiment. Next, a method of using the filtration device 10 according to the first embodiment will be briefly described. As shown in FIG. 6, a slurry supplying step S1 is first performed. The slurry supplying step S1 is a step of supplying a slurry 70 to the first filtration chamber 30 of the filtration device 10. In addition, in the slurry supplying step S1, the position of the third electrode 33 in the vertical direction is adjusted so that the third electrode 33 and the liquid surface of the slurry 70 are in contact with each other. Furthermore, a predetermined voltage is applied to the first electrode 31, the second electrode 32, and the third electrode 33. As a result, in the first filtration chamber 30, many particles 71 are distributed near the third electrode 33, and many water molecules 73 are distributed near the first electrode 31.

[0047] Next, the filtration process S2 is performed. The filtration process S2 is a process in which the third electrode 33 is continuously moved downward and a filtration pressure is applied to the slurry 70. As a result, many water molecules 73 in the slurry 70 near the first electrode 31 pass through the filter medium 34 and move to the second filter chamber 35. Since many particles 71 are located near the third electrode 33, the filter medium 34 is not clogged. Therefore, the water molecules 73 pass through the filter medium 34 smoothly. Furthermore, in the filtration process S2, since the third electrode 33 is continuously moved downward, the contact state between the third electrode 33 and the slurry 70 is maintained. In other words, the state in which the particles 71 are distributed near the third electrode 33 and the water molecules 73 are distributed near the first electrode 31 is maintained. Therefore, smooth filtration is continuously performed, and the filtration time is shortened.

[0048] Next, the squeezing step S3 is performed. The squeezing step S3 is a step of continuously moving the position of the third electrode 33 downward, as in the filtering step S2. As a result, the slurry 70 is pressed (squeezed) against the first electrode 31, the second electrode 32, and the filter medium 34. Most of the water molecules 73 contained in the slurry 70 move to the second filter chamber 35. As a result, the slurry 70 deposited on the filter medium 34 becomes the dehydrated cake 80. In this step, the particles 71 do not come into contact with the filter medium 34 as described above, so the squeezing time is shortened. Then, when the dehydrated cake 80 is generated, the downward movement of the third electrode 33 is stopped. At the same time, the supply of voltage to the first electrode 31, the second electrode 32, and the third electrode 33 is stopped. This ends the processing by the filtering device 10.

[0049] The above-mentioned configuration of the filtration device 10 is merely an example, and can be modified as appropriate. For example, the negative electrode filter plate formed by stacking the first electrode 31, the filter medium 34, and the second electrode 32, and the third electrode 33 are arranged in a parallel plate shape facing each other. Without being limited to this, the negative electrode filter plate formed by stacking the first electrode 31, the filter medium 34, and the second electrode 32, and the third electrode 33 may each be formed to have a curved surface. The shape and arrangement of the negative electrode filter plate and the third electrode 33 can be modified as appropriate according to the shape and structure of the filtration device 10. In addition, the concentration of the slurry (raw liquid) 70, which is the target treatment liquid supplied to the first filtration chamber 30, is not particularly limited, and can be modified according to the field to which the filtration device 10 is applied.

[0050] Moreover, it is preferable that the first potential V1 and the second potential V2 are appropriately changed according to the type of particles 71 to be separated and the required filtering characteristics.

[0051] As described above, the filtration device 10 of the first embodiment includes the first electrode 31 having a plurality of first openings 31b, the second electrode 32 having a plurality of second openings 32b and facing one surface of the first electrode 31, the filter medium 34 having a plurality of meshes 34b and provided between the first electrode 31 and the second electrode 32, the filter chamber (first filter chamber 30) provided in contact with the other surface of the first electrode 31 and supplied with a slurry (raw liquid) 70 (target treatment liquid) containing particles 71 to be separated and a polar solvent 72, and the first electrode 31 and the second electrode 32, or the third electrode 33 sandwiching the filter medium 34, are movable in the facing direction (up and down direction) in which the first electrode 31 and the third electrode 33 face each other. In the filtration device 10 of the first embodiment, the first electrode 31 is supplied with a first potential V1 having the same polarity as the polarity of the particles (particles 71). A second potential V2 having the same polarity as that of the particles (particles 71) is supplied to the second electrode 32. A reference potential GND is supplied to the third electrode 33. The absolute value of the second potential V2 is greater than the absolute value of the first potential V1.

[0052] According to the filtration device 10 of the first embodiment, the first electrode 31 and the second electrode 32 or the third electrode 33 move, and the slurry 70 accumulated on the filter medium is squeezed. In addition, by supplying a predetermined potential to the first electrode 31, the second electrode 32, and the third electrode 33, a repulsive force occurs between the first electrode 31 and the particles 71. As a result, the particles 71 move in a direction away from the first electrode 31 by electrophoretic flow. As a result, an increase in the filtration resistance of the surface of the first electrode 31 and the filter medium 34 is suppressed, and the filtration time is shortened. In addition, the discharge amount of water per unit time (the amount of water moving to the second filter chamber 35) is increased by electroosmosis, which causes the water molecules 73 to move by the electric field between the first electrode 31 and the second electrode 32 and pass through the filter medium 34. This further shortens the filtration time. In addition, the particles 71 move away from the first electrode 31 due to the repulsive force generated between the first electrode 31 and the particles 71, making it difficult for leakage of the particles to occur. Therefore, a polymer flocculant is not required. Since the third electrode 33 is connected to the reference potential GND, the filtration device 10 can be made smaller than when a power supply is provided for each of the first electrode 31, the second electrode 32, and the third electrode 33.

[0053] The filtering device 10 also includes a cylinder (not shown) that moves the upper housing 11 in the vertical direction (opposing direction).

[0054] This can reduce the effort required to move upper housing 11 and third electrode 33 in the vertical direction (opposing direction).

[0055] In addition, in embodiment 1, the upper housing 11 is moved up and down by a cylinder (not shown), but the side housing 13, the lower housing 14, and the conductor 15 (the first electrode 31, the second electrode 32, and the filter material 34) may also be moved up and down by a cylinder (not shown) to squeeze them.

[0056] (Embodiment 2) Fig. 7 is a cross-sectional view showing a schematic configuration example of a filtering device according to embodiment 2. Fig. 8 is an explanatory view for explaining the operation of the filtering device according to embodiment 2. Note that the same components as those described in the above-mentioned embodiments are given the same reference numerals, and duplicated explanations will be omitted.

[0057] As shown in Fig. 7, the filtration device 10 according to the second embodiment includes an upper housing 11, a cover 12, a side housing 13, a lower housing 14, a conductor 15, and a cylinder (not shown). The filtration device 10 further includes a first filtration chamber 30, a first electrode 31, a second electrode 32, a third electrode 33, and a filter medium 34 (see Fig. 8) in an internal space surrounded by the upper housing 11, the side housing 13, and the lower housing 14. A first power source 51, a second power source 52, and a third power source 53 are electrically connected to the filtration device 10.

[0058] One end of the through hole 11c opens to the top surface of the upper housing 11. The other end of the through hole 11c opens to the bottom surface of the upper housing 11 and is provided to be connected to a recess 33c of the third electrode 33. A connection conductor 56 is inserted into the through hole 11c, and the connection conductor 56 and the third electrode 33 are connected at the recess 33c. As a result, the third electrode 33 is electrically connected to a first terminal 53a of the third power source 53 via the connection conductor 56.

[0059] The first electrode 31 is electrically connected to the second terminal 51b of the first power supply 51 via the conductor 15 and the connecting conductor 54. The first electrode 31 is also electrically connected to the first terminal 52a of the second power supply 52 via the conductor 15 and the connecting conductor 55a. The second terminal 53b of the third power supply 53 and the first terminal 51a of the first power supply 51 are connected to a reference potential GND. The reference potential GND is, for example, a ground potential. However, the reference potential GND is not limited to this and may be a predetermined fixed potential.

[0060] Fig. 9 is an electrical equivalent circuit diagram showing a filtration device according to the second embodiment. As shown in Fig. 9, the first power source 51 and the third power source 53 are constant voltage sources, and the second power source 52 is a constant current source. A resistance component R1 and a capacitance component C are connected in parallel between the first electrode 31 and the second electrode 32. The resistance component R1 and the capacitance component C are components equivalently represented by the filter medium 34 having a large number of openings 34b. In addition, a resistance component R2 is connected between the first electrode 31 and the third electrode 33. The resistance component R2 is a resistance component equivalently represented by the slurry (raw liquid) 70 in the first filter chamber 30.

[0061] The second power source 52 may be a constant voltage power source or a constant current power source. In the second embodiment, the second power source 52 is a constant current source, so the second potential V12 changes according to the filtering state of the filtering device 10, that is, according to fluctuations in the resistance component R1 of the filtering medium 34 and the resistance component R2 of the first filtering chamber 30. However, the second potential V12 has the same polarity as that of the particles 71, and maintains a value greater than the absolute value of the first potential V11.

[0062] Next, the action and effect of each electrode (31, 32, 33) during squeezing of the filtration device 10 will be described with reference to FIG. 8. A repulsive force is generated between the negatively charged particle 71 and the first electrode 31. Also, an attractive force is generated between the negatively charged particle 71 and the third electrode 33. Therefore, a resultant force F3, which is a combination of the repulsive force and the attractive force generated in the negatively charged particle 71, acts in a direction away from the first electrode 31 and toward the third electrode 33. The negatively charged particle 71 moves toward the third electrode 33 by electrophoresis. From the above, during squeezing, the particles 71 are distributed toward the third electrode 33, and the particles 71 are prevented from clogging the mesh openings 34b of the filter medium 34. Therefore, the filtration resistance of the filter medium 34 does not increase until the end of squeezing.

[0063] Additionally, an attractive force F2 is generated between the positively charged water molecules 73 and the first electrode 31. The attractive force F2 acting on the positively charged water molecules 73 acts in the direction indicated by the arrow, that is, in the direction from the third electrode 33 to the first electrode 31. The positively charged water molecules 73 move toward the first electrode 31. At this time, due to the potential difference between the first electrode 31 and the second electrode 32, an electric field is formed from the first electrode 31 to the second electrode 32 so as to penetrate the filter medium 34 in the thickness direction.

[0064] The water molecules 73 that have moved to the first electrode 31 side are subjected to a force by the electric field and are pulled to the second electrode 32 side and pass through the filter medium 34. As the positively charged water molecules 73 move, uncharged water molecules are also pulled to the second electrode 32 side, forming an electroosmotic flow. As a result, the polar solvent 72 (filtrate 75) containing the positively charged water molecules 73 flows into the second filter chamber 35. Therefore, the amount of water discharged per unit time (the amount of water moving to the second filter chamber 35) increases compared to the case of simple squeezing, and the filtration process time is further shortened.

[0065] As described above, according to the filtration device 10 of the second embodiment, the filtration rate of the filter medium 34 is maintained at a high level (not clogged) for a long time, and the filtration process time is shortened. In addition, since the amount of water discharged per unit time (the amount of water moved to the second filter chamber 35) is increased, the filtration process time is further shortened. Furthermore, the particles 71 are subjected to a repulsive force from the first electrode 31, and filtration leakage is prevented. Therefore, a polymer flocculant that aggregates the particles 71 is not required.

[0066] In addition, in the second embodiment, the level of particles (particle diameter) passing through the filter medium 34 can be controlled by controlling the electric field E formed between the first electrode 31 and the second electrode 32. For example, by applying a first potential V11=-30V to the first electrode 31 and a second potential V12=-40V to the second electrode 32, a barrier electric field is formed between the first electrode 31 and the second electrode 32, and particles 71 having a particle diameter (5 nm or more and 2000 μm or less) smaller than the mesh opening (0.1 μm or more and 100 μm or less) 34b of the filter medium 34 can be prevented from passing through the filter medium 34.

[0067] That is, even when a filter medium 34 equivalent to a microfiltration membrane (MF membrane) is used, the particle size of the separation target can be changed to that of an ultrafiltration membrane (UF membrane) or a nanofiltration membrane (NF membrane) by controlling the electric field between each electrode of the first power source 51, the second power source 52, and the third power source 53. The ultrafiltration membrane (UF membrane) is a filtration membrane with an opening diameter of about 10 nm or more and 100 nm or less. The nanofiltration membrane (NF membrane) is a filtration membrane with an opening diameter of about 1 nm or more and 10 nm or less.

[0068] The above-mentioned configuration of the filtration device 10 is merely an example, and can be modified as appropriate. For example, the negative electrode filter plate formed by stacking the first electrode 31, the filter medium 34, and the second electrode 32, and the third electrode 33 are arranged in a parallel plate shape facing each other. Without being limited to this, the negative electrode filter plate formed by stacking the first electrode 31, the filter medium 34, and the second electrode 32, and the third electrode 33 may each be formed to have a curved surface. The shape and arrangement of the negative electrode filter plate and the third electrode 33 can be modified as appropriate according to the shape and structure of the filtration device 10. In addition, the concentration of the slurry (raw liquid) 70, which is the target treatment liquid supplied to the first filtration chamber 30, is not particularly limited, and can be modified according to the field to which the filtration device 10 is applied.

[0069] Moreover, it is preferable that the first potential V11, the second potential V12, and the third potential V13 are appropriately changed according to the type of particles 71 to be separated and the required filtering characteristics.

[0070] From the above, in the filtration device 10 of the second embodiment, a first potential V11 having the same polarity as the polarity of the particles (particles 71) is supplied to the first electrode 31. A second potential V12 having the same polarity as the polarity of the particles (particles 71) is supplied to the second electrode 32. A third potential V13 having a polarity different from the polarity of the particles (particles 71) is supplied to the third electrode 33. The absolute value of the second potential V12 is greater than the absolute value of the first potential V11.

[0071] According to the filtration device 10 of Embodiment 2, the first electrode 31 and the second electrode 32, or the third electrode 33 move, and the slurry 70 deposited on the filter medium is squeezed. Further, by supplying a predetermined potential to the first electrode 31, the second electrode 32, and the third electrode 33, a repulsive force acts between the first electrode 31 and the particles 71, and an attractive force acts between the third electrode 33 and the particles 71. As a result, the particles 71 move in the direction away from the first electrode 31 by the electrophoresis flow. As a result, an increase in the filtration resistance of the surface of the first electrode 31 and the filter medium 34 is suppressed, and the time for the filtration process is shortened. Further, by electroosmosis that moves the water molecules 73 through the filter medium 34 by the electric field between the first electrode 31 and the second electrode 32, the amount of water discharged per unit time (the amount of movement to the second filtration chamber 35) increases. Therefore, the time for the filtration process is further shortened. Further, due to the repulsive force generated between the first electrode 31 and the particles 71, the particles 71 move away from the first electrode 31, so that filtration leakage hardly occurs and a polymer flocculant becomes unnecessary.

[0072] In the filtration device 10 of Embodiment 2, a stronger repulsive force is generated on the particles 71 at a position closer to the first electrode 31 than in the filtration device 10 of Embodiment 1. As a result, a stronger attractive force is generated on the particles 71 at a position closer to the third electrode 33 than in the filtration device 10 of Embodiment 1. The resultant force F3 of the repulsive force (see F1 in FIG. 3) and the attractive force (f2) generated on the negatively charged particles 71 is in the relationship of F1 < F3 when compared with the force relationship of the repulsive force F1 generated on the particles 71 in the filtration device 10 of Embodiment 1, and the resultant force F3 of the repulsive force and the attractive force generated on the negatively charged particles 71 and the force moving toward the third electrode 33 by electrophoresis are large.

[0073] As described above, the filtration device 10 of Embodiment 2 includes the third electrode 33 as compared with the filtration device 10 of Embodiment 1, and by applying a predetermined potential to the third electrode 33, the resultant force F3 of the repulsive force and the attractive force acting between the third electrode 33 and the first electrode 31 increases the effect of separating from the first electrode 31 in the range of several nm to several μm. As a result, the timing at which the filtration resistance of the filter medium 34 increases is delayed. Therefore, the state where the filtration resistance of the filter medium 34 is small continues for a long time, and the filtration rate is further improved.

Description of Reference Numerals

[0074] 10 Filtration equipment 11 Upper case 12 Lid 13 Side housing 14 Lower housing 15 Conductor 16 Slurry supply section 17 Slurry supply valve 18 Air exhaust section 19 Valve 22 Discharge section 30 First Chamber 31 1st electrode 31a, 32a Conductive thin wire 31b 1st opening 32 2nd electrode 32b 2nd opening 33 Third electrode 34 Filter media 34a Filtration membrane 34b Opening 35 Second Chamber 51 1st power supply 52 2nd power supply 53 Third power supply 70 Slurry (undiluted) 71 First particle (particle to be separated) 72 Polar Solvents 73 Water molecules 75 Filtrate F1 repulsion F2 Gravity F3 resultant force

Claims

1. a first electrode having a plurality of first openings; a second electrode having a plurality of second openings and facing one surface of the first electrode; A filter medium having a plurality of openings and disposed between the first electrode and the second electrode; a filter chamber provided in contact with the other surface of the first electrode and receiving a target processing liquid containing particles to be separated and liquid; a third electrode facing the first electrode across the filtration chamber; The first electrode and the second electrode, or the third electrode, which sandwich the filter medium, are movable in a direction in which the first electrode and the third electrode face each other. Filtration equipment.

2. A first potential is applied to the first electrode, the first potential having the same polarity as the polarity of the particles; the second electrode is supplied with a second potential having a polarity that is the same as the polarity of the particles; A reference potential is applied to the third electrode; The absolute value of the second potential is greater than the absolute value of the first potential. The filtration device of claim 1 .

3. A first potential is applied to the first electrode, the first potential having the same polarity as the polarity of the particles; A second potential is applied to the second electrode, the second potential having the same polarity as the polarity of the particles; a third potential having a polarity different from that of the particles is applied to the third electrode; The absolute value of the second potential is greater than the absolute value of the first potential. The filtration device of claim 1 .

4. a side housing having a through hole, a lower housing supporting the side housing, and an upper housing inserted into the through hole of the side housing, The first electrode, the second electrode, and an outer edge of the filter medium are sandwiched and fixed between the side housing and the lower housing, the third electrode is fixed to a surface of the upper housing facing the lower housing, The filter chamber is formed in a space surrounded by the first electrode, the second electrode, the filter medium, an inner wall of the side housing, and the third electrode, The side housing and the lower housing are connected to each other so as to be slidable in the opposing direction. The filtration device according to any one of claims 1 to 3.

5. a cylinder for moving the upper housing in the opposing direction; The filtration device according to claim 4.

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