JP2024061484A - Filtration Membrane Unit - Google Patents

Abstract

A filtration membrane unit is provided that can improve purification action by preventing fouling from concentrating at specific locations on the filtration membrane, and can extend operating time by reducing cleaning frequency.
[Solution] A filtration membrane unit 1 is configured by stacking a plurality of membrane modules 2, each of which is made of a pair of sheet-like members with a gap S formed between the pair of sheet-like members, and each of which has a filtration membrane (3a, 3b) that introduces purified water obtained by filtering water to be purified into the gap S, and a nozzle portion 6 that sucks in the purified water introduced into the gap S and discharges it to the outside, wherein the nozzle portion 6 is equipped with a suction port 6a consisting of a long groove that opens along the edge of the filtration membrane (3a, 3b) facing the gap S and can suck in the purified water in the gap S, and a discharge outlet 6b that discharges the purified water sucked from the suction port 6a to the outside of the membrane module 2.
[Selected figure] Figure 7

Description

The present invention relates to a filtration membrane unit in which multiple membrane modules, each having a filtration membrane and a nozzle section, are stacked and arranged.

One example of a purification technology for obtaining purified water by filtering sludge is a membrane filtration unit having a membrane module known as the membrane bioreactor (MBR). As disclosed in Patent Document 1, for example, the membrane module (particularly a flat membrane module) used in a conventional membrane filtration unit is equipped with sheet-like filtration membranes arranged opposite each other, a support interposed between the filtration membranes, and a nozzle portion formed at a predetermined position of the filtration membrane, and is configured so that purified water filtered by the filtration membranes is sucked into the nozzle portion and discharged to the outside.

International Publication No. 2014/010554

However, in the conventional membrane module described above, because the nozzle portion is formed on part of the outer periphery of the filtration membrane, the flow rate of the purified water is significantly higher near the nozzle portion than in other areas, and fouling (clogging due to the adhesion of sludge material) occurs in a concentrated manner near the nozzle portion. When fouling occurs in a concentrated manner in one area, the purification effect of the entire filtration membrane is reduced, and the frequency of cleaning of the filtration membrane is increased, resulting in a reduced operating time.

The present invention was made in consideration of these circumstances, and aims to provide a filtration membrane unit that can prevent fouling from concentrating on specific parts of the filtration membrane, improve the purification effect, and reduce the frequency of cleaning to extend the operating time.

The invention described in claim 1 is a filtration membrane unit in which a plurality of membrane modules are stacked and arranged, each of which has a pair of sheet-like members capable of capturing and filtering impurities contained in water to be purified, a gap formed between the pair of sheet-like members, a filtration membrane that filters the water to be purified and introduces the purified water into the gap, and a nozzle portion that sucks in the purified water introduced into the gap and discharges it to the outside, and the nozzle portion is characterized in that it has a suction port consisting of a long groove that opens along the edge of the filtration membrane while facing the gap and can suck in the purified water in the gap, and a discharge outlet that discharges the purified water sucked from the suction port to the outside of the membrane module.

The invention described in claim 2 is characterized in that in the filtration membrane unit described in claim 1, the nozzle portion is formed in a holding portion that holds a pair of the filtration membranes facing each other.

The invention described in claim 3 is characterized in that in the filtration membrane unit described in claim 2, the filtration membrane is formed in a rectangular shape in a plan view, and a pair of opposing side edges are each held by the holding portion.

The invention described in claim 4 is the filtration membrane unit described in claim 1, characterized in that the membrane module has a porous member housed in the gap.

The invention described in claim 5 is characterized in that the filtration membrane unit described in claim 1 is provided with an air bubble ejection section that ejects air bubbles toward the membrane module.

According to the invention described in claim 1, the nozzle portion is provided with a suction port consisting of a long groove that opens along the edge of the filtration membrane while facing the gap and can suck in purified water from the gap, and an outlet port that discharges the purified water sucked from the suction port to the outside of the membrane module. This makes it possible to prevent fouling from concentrating on a specific part of the filtration membrane, improving the purification action, and reducing the frequency of cleaning to extend the operating time.

According to the invention described in claim 2, the nozzle portion is formed in a holding portion that holds a pair of filtration membranes facing each other, so that the nozzle portion can be formed using the holding portion, and the suction port and outlet port of the nozzle portion can be easily formed.

According to the invention described in claim 3, the filtration membrane is formed in a rectangular shape in a plan view, and a pair of opposing side edges are each held by a holding portion, so that the longitudinal dimension of the suction port formed in the holding portion can be set large, and the fouling suppression effect can be further improved.

According to the invention described in claim 4, the membrane module has a porous member housed in the gap, so that the gap can be spaced at the desired distance and purified water can be efficiently introduced into the gap.

According to the invention described in claim 5, the device is provided with an air bubble ejection section that ejects air bubbles toward the membrane module, so that sludge material adhering to the filtration membrane can be easily removed by ejecting air bubbles.

FIG. 1 is an external perspective view showing a filtration membrane unit according to an embodiment of the present invention. FIG. 2 is an external perspective view showing the lower and rear sides of the filtration membrane unit. 3D diagram showing a stacked unit of the filtration membrane unit. FIG. 3 is a three-view diagram showing the membrane module constituting the laminated unit. FIG. 1 is a perspective view showing a nozzle portion (outlet) of the membrane module. FIG. 2 is a perspective view showing a holding part (first holding part) in which nozzles (suction port and outlet port) are formed in the membrane module. 5 is a schematic diagram showing a cross section of the membrane module; (a) is a cross section taken along line A-A in FIG. 4; (b) is a cross section taken along line B-B in FIG. 4; FIG. 4 is a schematic cross-sectional view showing the laminated structure of the laminate unit (cross-sectional view taken along line CC in FIG. 3). FIG. 2 is a perspective view showing an integrated structure of the laminated unit; FIG. 1 is an external view showing a membrane module according to another embodiment of the present invention. FIG. 1 is an external view showing a membrane module according to another embodiment of the present invention.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
The filtration membrane unit 1 of this embodiment is installed in a septic tank that stores water to be purified that contains sludge, and is capable of filtering and purifying the water to be purified. As shown in Figures 1 to 8, the filtration membrane unit 1 is configured to include a plurality of stacked units M inside a box-shaped frame F, and each stacked unit M is integrated by stacking a plurality of membrane modules 2, as shown in Figures 3 and 9.

The membrane module 2 has a filtration membrane (3a, 3b), a first holding portion 4, a second holding portion 5, and a nozzle portion 6. The filtration membrane (3a, 3b) is made of a pair of sheet-like members capable of capturing and filtering impurities such as sludge contained in the water to be purified, and is formed in a rectangular shape in a plan view as shown in FIG. 4, with a pair of opposing side edges held by the first holding portion 4 and the second holding portion 5, respectively.

Such filtration membranes (3a, 3b) are made of, for example, a structure having chemical fibers (e.g., polypropylene, acrylic, aramid resin, or polyethylene terephthalate), and specific materials include polysulfone (PSF), polyvinylidene fluoride (PVDF), polyethersulfone (PES), polyimide (PI), polyvinyl chloride (PVC), cellulose acetate (CA), etc.

In the filtration membranes (3a, 3b) of this embodiment, a gap S is formed between a pair of sheet-like members, and purified water obtained by filtering the water to be purified is introduced into the gap S. That is, the filtration membranes 3a and 3b are arranged opposite each other with a predetermined distance between them, and a gap S is formed between these filtration membranes 3a and 3b, so that the water to be purified passes through each of the filtration membranes (3a, 3b) and is filtered in the process of reaching the gap S, and the purified water is introduced into the gap S.

In addition, a porous member W is housed in the gaps S of the filtration membranes (3a, 3b), so that the gaps S are maintained even when negative pressure is applied. Examples of materials for the porous member W include polyvinyl alcohol (PVA), ethylene vinyl acetate (EVA), polypropylene (PP), and polyethylene (PE). Note that a mesh member may be housed in the gaps S instead of or in addition to the porous member W.

As shown in FIG. 4, the first holding part 4 and the second holding part 5 are made of elongated members that hold a pair of filtration membranes (3a, 3b) facing each other, and have a welding surface D for welding the edges of the filtration membranes (3a, 3b). That is, as shown in FIG. 7, the filtration membranes (3a, 3b) are supported by having both side edges of each of them welded (or may be glued) to the welding surfaces D of the first holding part 4 and the second holding part 5 by ultrasonic welding, hot plate welding, or the like, so that a gap S is formed between them.

As shown in FIG. 4, the first holding part 4 supports one side edge (the left side edge in the figure) of the filtration membranes (3a, 3b) on its welding surface D, and the second holding part 5 supports one side edge (the left side edge in the figure) of the filtration membranes (3a, 3b) on its welding surface D, thereby supporting the filtration membranes (3a, 3b) in an opposing state. The upper and lower edges of the filtration membranes (3a, 3b) are sealed to each other by welding (or may be glued) using ultrasonic welding, hot plate welding, or the like.

The material of the first holding part 4 and the second holding part 5 may be a thermoplastic resin such as polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), polycarbonate (PC), polyacetal (POM), ABS, polyphenylene sulfide (PPS), etc.

The nozzle portion 6 sucks up the purified water introduced into the gap portion S and discharges it to the outside, and in this embodiment, it is composed of an inlet port 6a and an outlet port 6b formed in the first holding portion 4. As shown in Figures 6 and 7, the inlet port 6a is a long groove that opens along the edge (side edge) of the filtration membrane (3a, 3b) facing the gap portion S and can suck up the purified water in the gap portion S, and is formed along the longitudinal direction on the side surface (inner surface) of the first holding portion 4.

The outlet 6b is connected to a part of the suction port 6a (in this embodiment, at a position above the filtration membranes (3a, 3b)) and is formed to protrude toward the side of the membrane module 2 as shown in FIG. 5, and is configured to discharge the purified water sucked from the suction port 6a to the outside of the membrane module 2. The outlet 6b is connected to the suction pipe section 7 (see FIG. 2) attached to the frame F, and when negative pressure is generated by a negative pressure generator (not shown) connected to the suction pipe section 7, negative pressure is generated in the gap section S via the suction pipe section 7.

In this way, by generating negative pressure in the gap S, the water to be purified is sucked toward the gap S of the filtration membranes (3a, 3b), and the purified water filtered as it passes through the filtration membranes (3a, 3b) is introduced into the gap S. The introduced purified water is then discharged to the outside via the nozzle section 6, and is then stored outside the filtration membrane unit 1 (such as a purified water storage tank installed outside the septic tank) via the suction pipe section 7.

As shown in Figure 3, a stacked unit M can be obtained by stacking and integrating multiple membrane modules 2. As shown in Figures 8 and 9, the stacked unit M is formed by stacking multiple membrane modules 2, overlapping the first holding parts 4 and the second holding parts 5 of adjacent membrane modules 2, stacking metal plates H on both ends, and then inserting a metal shaft L to prevent them from coming loose, thereby integrating the stacked units.

However, the first and second holding parts 4 and 5 of the adjacent membrane modules 2 are configured to overlap with each other to space the filtration membranes (3a, 3b) of the adjacent membrane modules 2 by a predetermined distance. That is, as shown in FIG. 8, the width dimension t of the portion (wide end portion) of the first and second holding parts 4 and 5 of the membrane module 2 according to this embodiment that overlaps with the first and second holding parts 4 and 5 of the adjacent membrane module 2 is set according to the spacing dimension u (membrane spacing dimension) of the filtration membranes (3a, 3b). Therefore, when a plurality of membrane modules 2 are stacked to form a stacked unit M, the first and second holding parts 4 and 5 of the adjacent membrane modules 2 are positioned to overlap with each other to achieve the spacing dimension u (membrane spacing dimension).

In addition, in the stacked unit M according to this embodiment, as shown in FIG. 3, the outlets 6b of the nozzle parts 6 in the adjacent membrane modules 2 are formed to protrude at positions that are vertically shifted (offset positions). This allows the outlets 6b to have a predetermined size, ensuring a sufficient flow rate of purified water discharged from the gap part S, and preventing adjacent outlets 6b from interfering with each other.

As shown in FIG. 6, the suction port 6a in this embodiment is a long groove that opens along the edge of the filtration membrane (3a, 3b) facing the gap S and can suck in the purified water in the gap S. Therefore, the purified water in the gap S can be sucked in over the entire side of the filtration membrane (3a, 3b) (see the arrow in FIG. 4), and the flow rate of the sucked purified water can be prevented from becoming locally high.

As shown in Figures 1 and 2, the filtration membrane unit 1 according to this embodiment is provided with an air bubble ejection section 8 attached below the location where the stacked unit M is installed. The air bubble ejection section 8 is made of a circulating pipe that can eject air bubbles from a plurality of air bubble holes while circulating the supplied air, and is capable of removing sludge material adhering to the filtration membranes (3a, 3b) by ejecting air bubbles toward the membrane module 2.

According to the filtration membrane unit 1 of this embodiment, the nozzle portion 6 is provided with a suction port 6a consisting of a long groove that opens along the edge of the filtration membrane (3a, 3b) facing the gap portion S and can suck in the purified water in the gap portion S, and an outlet port 6b that discharges the purified water sucked from the suction port 6a to the outside of the membrane module 2. This makes it possible to prevent fouling from concentrating on a specific portion of the filtration membrane (3a, 3b) and improve the purification action, and also reduces the frequency of cleaning to extend the operating time.

In addition, the nozzle portion 6 according to this embodiment is formed in a holding portion (first holding portion 4) that holds a pair of filtration membranes (3a, 3b) facing each other, so that the nozzle portion 6 can be formed using the first holding portion 4, and the suction port 6a and the outlet port 6b of the nozzle portion 6 can be easily formed. Furthermore, the filtration membranes (3a, 3b) according to this embodiment are formed in a rectangular shape in a plan view, and a pair of opposing side edges are each held by the holding portion (first holding portion 4 and second holding portion), so that the longitudinal dimension of the suction port 6a formed in the first holding portion 4 can be set large, and the fouling suppression effect can be further improved.

Furthermore, in the membrane module 2 according to this embodiment, the porous member W is housed in the gap S, so that the gap S can be ensured to have the desired spacing dimension, and purified water can be smoothly introduced into the gap S. In addition, the filtration membrane unit 1 according to this embodiment is equipped with an air bubble ejection section 8 that ejects air bubbles toward the membrane module 2, so that sludge material adhering to the filtration membrane (3a, 3b) can be easily removed by ejecting air bubbles.

However, the holding parts (first holding part 4 and second holding part 5) overlap when the membrane modules 2 are stacked, and space the filtration membranes (3a, 3b) of adjacent membrane modules 2 apart by a predetermined distance, making it possible to eliminate the need for intervening objects or intervening mechanisms such as spacers, and to reliably space the filtration membranes (3a, 3b) of adjacent membrane modules 2 apart by a predetermined distance without increasing the number of parts.

Furthermore, the width dimension t of the overlapping portion of the holding portion (first holding portion 4 and second holding portion 5) of the adjacent membrane module 2 in this embodiment is set according to the separation dimension u of the filtration membranes (3a, 3b). Therefore, the separation dimension u of the filtration membranes (3a, 3b) in the adjacent membrane module 2 can be adjusted arbitrarily by changing the width dimension t of the overlapping portion of the holding portion (first holding portion 4 and second holding portion 5).

Although the present embodiment has been described above, the present invention is not limited to this. For example, as shown in FIG. 10, the nozzle portion 6 (suction port 6a and outlet port 6b) may be formed in both the first holding portion 4 and the second holding portion 5, or as shown in FIG. 11, the outlet port 6b of the nozzle portion 6 may be formed at the center position of the first holding portion 4 (or the second holding portion 5). In addition, spacers may be attached between adjacent membrane modules 2, and the separation dimension u (intermembrane dimension) of the filtration membranes (3a, 3b) may be adjusted as desired.

The filter membrane unit can be applied to other configurations as long as it is equipped with a nozzle portion having a suction port consisting of a long groove that opens along the edge of the filter membrane facing the gap and can suck in purified water from the gap, and an outlet port that discharges the purified water sucked in from the suction port to the outside of the membrane module.

Reference Signs List 1 Filtration membrane unit 2 Membrane modules 3a, 3b Filtration membrane 4 First holding portion 5 Second holding portion 6 Nozzle portion 6a Suction port 6b Outlet 7 Suction pipe portion 8 Bubble ejection portion M Stacking unit S Gap portion W Porous member F Frame D Welding surface

Claims (5)

A filtration membrane is composed of a pair of sheet-like members capable of capturing and filtering impurities contained in the water to be purified, and a gap is formed between the pair of sheet-like members, and purified water obtained by filtering the water to be purified is introduced into the gap;
A nozzle portion that sucks the purified water introduced into the gap and discharges it to the outside;
A filtration membrane unit in which a plurality of membrane modules having the same are stacked and arranged,
The nozzle portion is characterized in that it comprises an suction port consisting of a long groove that opens along the edge of the filtration membrane while facing the gap portion and can suck in the purified water from the gap portion, and an outlet port that discharges the purified water sucked from the suction port to the outside of the membrane module. The filtration membrane unit according to claim 1, characterized in that the nozzle portion is formed in a holding portion that holds a pair of the filtration membranes facing each other. The filtration membrane unit according to claim 2, characterized in that the filtration membrane is formed in a rectangular shape in a plan view, and a pair of opposing side edges are each held by the holding portion. The filtration membrane unit according to claim 1, characterized in that the membrane module contains a porous material in the gap. The filtration membrane unit according to claim 1, characterized in that it is provided with a bubble ejection section that ejects bubbles toward the membrane module.

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