HK1095551B - Membrane cartridge, membrane separating device, and membrane separating method - Google Patents

Description

Membrane cartridge, membrane separation device, and membrane separation method

Technical Field

The present invention relates to a filter cartridge using a hollow fiber membrane, which is attached to a pressurized or suction box-type filter device or a submerged filter device. More particularly, the present invention relates to a hollow fiber membrane cartridge used in a filtration apparatus for removing turbidity and bacteria from raw water such as river water, lake water, underground water, sea water, domestic wastewater, factory wastewater, and wastewater secondary treatment water, or in a membrane-activated sludge separation apparatus for performing solid-liquid separation of activated sludge by using a membrane.

Background

As one of the methods for treating wastewater, there is a membrane separation activated sludge method in which a membrane cartridge is immersed in an activated sludge tank and solid-liquid separation of activated sludge and treated water is performed by filtration. The method can extremely increase the concentration of activated sludge (MLSS) to 5000-20000 mg/l for filtration treatment, and thus has the advantage of reducing the volume of the activated sludge tank or shortening the reaction time in the activated sludge tank. Further, since filtration is performed by a membrane, Suspended Solids (SS) do not mix into the treated water, a final settling tank is not required, the floor space of the treatment facility can be reduced, and since filtration is possible regardless of the settling property of the activated sludge, the activated sludge control can be reduced, and this has many advantages, and thus, the present invention has been rapidly spread in recent years.

When a hollow fiber membrane is used for the membrane cartridge, the membrane itself has high strength, so that the damage of the membrane surface due to the contact with impurities mixed in from raw water is small, and the membrane cartridge can withstand long-term use. Further, there is an advantage that backwashing can be performed in which a medium such as treated water is ejected in a direction opposite to the filtration direction to remove deposits on the membrane surface. However, if filtration is not performed while excluding aggregates of activated sludge accumulated in the gaps between the hollow fiber membranes and foreign substances carried in the raw water, the effective membrane area is reduced. As a result, there is a problem that stable filtration for a long time cannot be performed due to a decrease in filtration efficiency.

Conventionally, aeration of air or the like is performed from the lower part of the membrane cartridge in order to avoid accumulation of sludge or the like on the surface of the hollow fiber membranes and between the hollow fiber membranes. Thus, the activated sludge aggregates on the surface of the hollow fiber membranes and between the hollow fiber membranes are separated from the impurities entrained in the raw water by the membrane oscillation effect and the agitation effect by the upward movement of the bubbles, thereby preventing the accumulation of the activated sludge aggregates. For example, a lower ring (or also called a skirt) is provided at the lower part of the hollow fiber membrane cartridge, and a plurality of through holes are formed in the lower ring-side adhesive layer, so that gas stagnation is formed at the end of the lower ring protruding from the lower ring by aeration from the lower part of the cartridge. Thus, the bubbles are uniformly generated by the plurality of through holes, and the suspended matter deposited on the outer surface of the hollow fiber membrane is easily peeled off (see, for example, Japanese patent laid-open No. 2000-157846).

However, in the case of filtration treatment of high-concentration MLSS such as the membrane separation activated sludge method, although there is an effect of stripping sludge between hollow fiber membrane bundles by the stirring effect of aeration and the oscillation effect of the membrane, a force of lifting up activated sludge aggregates and foreign substances is also exerted due to the rise of air bubbles. In the bundle near the filter element head, they are not completely discharged to the outside of the bundle, but gradually accumulated. Further, when the aeration amount is increased, sludge aggregates and foreign substances passing through the hollow fiber membranes are also increased. As a result, sludge deposits and foreign substances are further deposited in the membrane bundle near the filter element head, and the surface of the hollow fiber membrane is clogged.

Disclosure of Invention

The present invention relates to a membrane cartridge, a membrane separation method, and a membrane separation apparatus, which prevent accumulation of sludge aggregates, foreign matters, and the like in a hollow fiber membrane cartridge with a minimum required aeration amount and have stable filtration performance for a long period of time.

The present inventors have made extensive studies and as a result, have found that the arrangement of the hollow fiber membrane cartridge as described below makes it possible to minimize the escape of bubbles aerated from below the lower ring to the outside before reaching the cartridge head. Further, it has been found that by providing a structure in which a bundle of hollow fiber membranes is present at a predetermined interval or more near the filter element head, sludge aggregates or foreign substances are discharged to the outside of the filter element without accumulating between the hollow fiber membranes of the filter element, and the present invention has been developed.

That is, the present invention is configured as follows.

(1) A hollow fiber membrane cartridge comprising 1 or more hollow fiber membrane bundles each composed of a plurality of hollow fiber membranes and having both ends adhesively fixed to each other by an adhesive layer, a cartridge head liquid-tightly fixed to the outer periphery of one end of the hollow fiber membrane bundle, and a lower ring fixed to the outer periphery of the other end, wherein:

the hollow portion of the hollow fiber membrane is opened at the end portion of the filter element head side, the hollow portion of the hollow fiber membrane is sealed in the lower ring side adhesive fixing layer, a plurality of through holes are provided in the lower ring side adhesive fixing layer, the through holes are arranged in the hollow fiber membrane bundle, the end portion of the lower ring is more protruded than the end face of the lower ring side adhesive fixing layer, and at least a part of the hollow fiber membrane bundle is divided into a plurality of small bundles of 2 or more on the filter element head side adhesive fixing layer.

(2) The hollow fiber membrane cartridge according to (1), wherein the at least a part of the hollow fiber membrane bundles are divided into a plurality of 2 or more bundles on the way from the lower ring side adhesive layer to the cartridge head side adhesive layer.

(3) The hollow fiber membrane cartridge according to (1), wherein the bundles of hollow fiber membranes on the filter section interface of the cartridge head side adhesion fixing layer are such that the distance between the nearest hollow fiber membranes in each bundle is less than 2mm, the number of hollow fiber membranes is 10 or more and 1000 or less, and the distance between the nearest bundles is 2mm or more and 100mm or less.

(4) The hollow fiber membrane cartridge according to (1), wherein the bundles of hollow fiber membranes at the filter section interface of the cartridge head side adhesive-fixing layer are arranged on 1 or more concentric circles.

(5) The hollow fiber membrane cartridge according to (4), wherein the hollow fiber membrane bundle is present in all directions from a center portion to an outer peripheral portion of a concentric circle of a filter section interface of the cartridge head side adhesion fixing layer.

(6) The hollow fiber membrane cartridge according to item (1), wherein the hardness of the resin forming the filter part interface of the cartridge head side and the lower ring side adhesive fixing layers (measured in accordance with JISK6253 and ISO 7619) is 20A or more and 90A or less.

(7) A membrane separation device wherein a hollow fiber membrane cartridge according to any one of (1) to (6) is vertically arranged in a vessel having an inflow port, and a gas inlet port for ejecting a gas for oscillating the hollow fiber membrane through a plurality of through holes in a lower ring side adhesive fixing layer during filtration and/or backwashing is provided below a lower ring of the hollow fiber membrane cartridge.

(8) A membrane separation method wherein raw water to be treated is caused to flow into a vessel, and then suction filtration and backwashing are carried out while aeration is carried out from below the lower ring of a hollow fiber membrane cartridge according to any one of (1) to (6) arranged in the vertical direction in the vessel.

By the operation of the hollow fiber membrane cartridge and the membrane separation device of the present invention, accumulation of sludge on the surface of the hollow fiber membrane can be prevented, and stable filtration performance over a long period of time can be achieved at low cost.

Drawings

Fig. 1 is a cross-sectional explanatory view showing an example of an embodiment of a hollow fiber membrane cartridge according to the present invention.

FIG. 2 is a cross-sectional explanatory view showing an example of an embodiment of the membrane separation apparatus of the present invention.

Fig. 3(a) to (e) are schematic diagrams showing examples of the arrangement of small bundles of hollow fiber membranes at the filter section interface of the cartridge head side adhesive fixing layer in the membrane separation device of the present invention.

Fig. 4(a) to (f) are schematic diagrams showing examples of the arrangement of the bundles of hollow fiber membranes at the filter unit interface bonded and fixed to the cartridge head side in the membrane separation devices of examples 1 to 6, and fig. 4(g) is a schematic diagram showing an example of the arrangement of the hollow fiber membranes at the filter unit interface of the cartridge head side bonded and fixed layer in the membrane separation device of comparative example 1.

Description of the reference symbols

1 hollow silk membrane bundle 2 filter element head

3 lower ring 4 filter element side adhesive fixing layer

5 lower ring side bonding fixed layer 6 filter element head side bonding fixed layer end face

7 lower ring side adhesive fixed layer end face 8 through hole

9 lower ring side end 10 small bundle

11 side core rod 12 filter part

13 filter part interface of filter element side bonding fixed layer

14 filter part interface of lower ring side adhesive fixing layer

15 membrane separation device 16 container

17 inflow port 18 hollow fiber membrane filter element

19 treated water outlet of gas jet port 20 for aeration

21 gas introducing pipe for aeration

Detailed Description

Hereinafter, an example of an embodiment of the hollow fiber membrane cartridge according to the present invention will be described with reference to fig. 1. The hollow fiber membrane cartridge comprises a hollow fiber membrane bundle 1 composed of a plurality of hollow fiber membranes (in the hollow fiber membrane cartridge of the present invention, one or a plurality of hollow fiber membrane bundles may be provided, and in this embodiment, one hollow fiber membrane bundle is provided), a cartridge head 2 and a lower ring 3 are provided at both ends of the hollow fiber membrane bundle 1, and the hollow fiber membranes are fixed by a cartridge head side adhesive fixing layer 4 and a lower ring side adhesive fixing layer 5. The hollow fiber membrane is open at the end on the filter element head side (the filter element head side adhesive fixing layer end face 6), and the hollow portion of the hollow fiber membrane is sealed at the end on the lower ring side (in the lower ring side adhesive fixing layer). The lower ring 3 has a lower ring end 9 protruding beyond the end face of the lower ring-side adhesive/fixing layer. The lower ring side adhesive fixing layer 5 has a plurality of through holes 8. The hollow fiber membrane bundle 1 is divided into a plurality of 2 or more small bundles 10 on the filter element head side adhesive fixing layer 4. In general, in the hollow fiber membrane cartridge of the present invention, the hollow fiber membrane bundle is divided into a plurality of small bundles of 2 or more at positions other than the cartridge head side adhesive fixing layer. The filter element head 2 and the lower ring 3 are joined together by means of side plugs 11. In the hollow fiber membrane, a portion not included in the adhesive fixing layers at both ends is defined as a filter part 12, a portion facing the filter part side in the filter element head side adhesive fixing layer 4 is defined as a filter part interface 13 of the filter element head side adhesive fixing layer, and a portion facing the filter part in the lower ring side adhesive fixing layer 5 is defined as a filter part interface 14 of the lower ring side adhesive fixing layer.

In the hollow fiber membrane cartridge of the present invention, as described above, one or more hollow fiber membrane bundles may be provided. When the number of the hollow fiber membrane bundles is plural, all of them may be divided into plural bundles, or may include bundles which are not divided into plural bundles. When there is one hollow fiber membrane bundle, the hollow fiber membrane bundle is divided into a plurality of small bundles (in the case of the present embodiment).

The bubbles passing through the plurality of through holes in the lower ring-side adhesive fixing layer rise substantially vertically in the space between the hollow fiber membranes while giving a swing to the hollow fiber membranes. However, in the vicinity of the filter element head side adhesive fixing layer, the amplitude of the hollow fiber membrane is reduced, the void is also reduced, and the air bubbles are not allowed to rise, but are diffused in the circumferential direction and discharged to the outside of the filter element. When the filling rate of the membrane is increased and the space between the hollow fiber membranes is small, solid matter, fibrous matter, and sludge deposits contained in the sludge cannot pass through and stay between the hollow fiber membranes, thereby reducing the filtration area and making filtration difficult.

In order to easily remove the sludge accumulated matter while increasing the filling ratio of the hollow fiber membranes, it is necessary to form a portion having a relatively low density in the hollow fiber membranes in the vicinity of the head-side adhesive layer of the filter element and provide a flow path through which the sludge accumulated matter passes. That is, a structure in which the hollow fiber membranes are divided into a plurality of small bundles of 2 or more and the space between the hollow fiber membrane bundles is used as a flow path for aeration bubbles and sludge accumulation is effective.

In addition, in the case of dividing the hollow fiber membrane into a plurality of bundles of 2 or more between the lower ring side adhesive fixing layer and the filter element head side adhesive fixing layer, it is preferable to prevent the aeration from the lower part of the lower ring from being released to the outside of the filter element, and to improve the cleaning effect. The hollow fiber membranes are preferably formed in a plurality of layers which are interlaced with each other from the lower ring side adhesive layer to the filter element head adhesive layer, so that the effect of the oscillation by the aeration can be further increased and the escape to the outside of the filter element can be prevented.

The bundles of hollow fiber membranes in the filter side interface of the filter element head side adhesive-fixing layer are preferably such that the distance between the hollow fiber membranes closest to each other in each bundle is preferably less than 2mm, more preferably less than 1mm, and the area of the hollow fiber membranes can be increased to improve the drainage of the membrane filter element. The distance between the hollow fiber membranes as used herein means the distance between the outermost surfaces of the hollow fiber membranes. The number of the hollow fiber membranes forming the small bundle is preferably not less than 10 and not more than 1000, more preferably not less than 20 and not more than 300. Within this range, accumulation of sludge aggregates and inclusions between the hollow fiber membranes is extremely reduced. The distance between the closest beamlets is preferably equal to or greater than 2mm and equal to or less than 100mm, more preferably equal to or greater than 3mm and less than 30 mm. Within this range, the hollow fiber membrane can be filled at a high filling rate without accumulation of sludge and foreign matter, and the amount of filtered water can be increased. The distance between the small bundles herein means the closest distance among the distances between the outermost surfaces of the hollow fiber membranes included in the small bundles.

By adopting a structure in which the bundles of hollow fiber membranes at the interface of the filter unit of the filter element head side adhesive fixing layer are arranged on 1 or more concentric circles, the aeration bubbles can be discharged uniformly in the circumferential direction, and therefore the sludge deposit removal effect can be exhibited with the minimum aeration amount.

Further, since the bundle of hollow fiber membranes is provided in all directions from the center to the outer peripheral portion of the concentric circle of the filter unit interface of the filter element head-side adhesive fixing layer (that is, the center of the filter unit-side interface of the filter element head-side adhesive fixing layer is not visible from the outside of the filter element, or when an arbitrary line is drawn from the center to the outer peripheral portion of the concentric circle, the bundle of hollow fiber membranes is passed in all cases), the flow of the aerated gas does not deviate in a direction from the center to a part of the outer peripheral portion of the filter element, and sludge deposits and foreign substances can be uniformly removed.

The number of hollow fiber membranes contained in the bundles may be the same or different from each other as long as the number is within the above range, but it is preferable that the number of hollow fiber membranes contained in the bundles is the same in all the bundles and/or the arrangement intervals of the bundles on the concentric circles are uniform, in order to uniformly discharge sludge deposits.

The shape of the hollow fiber membrane bundle (bundle) may be any shape such as a circle, an ellipse, or a polygon, but it is preferable to discharge the sludge deposit uniformly in such a manner that all the bundles are the same shape or all the bundles on the same circumference are the same shape.

On the other hand, the hollow fiber membranes of the lower ring side adhesive fixing layer may be in a single bundle structure or divided into a plurality of small bundles, but it is preferable that the air bubbles aerated particularly in a single bundle are hardly dispersed to the filter element head.

When the bundle of hollow fiber membranes is divided into a plurality of bundles of 2 or more, it is preferable that the hollow fiber membranes are interlaced between the lower ring side adhesive fixing layer and the filter element head side fixing layer in order to prevent the aerated air bubbles from escaping to the outside of the filter element.

Hereinafter, an example of an embodiment of a membrane separation apparatus using the hollow fiber membrane cartridge of the present invention will be described with reference to fig. 2.

In fig. 2, the hollow fiber membrane cartridge 18 is composed of a plurality of hollow fiber membrane bundles 1 formed by collecting hollow fiber membranes, a cartridge head 2, and a lower ring 3. One end of the bundle of hollow fiber membranes 1 is integrally bonded to each other with an adhesive, and is integrally bonded to the inside of the filter element head-side fixing layer 4. The end of the hollow fiber membrane on the end surface of the cartridge head 2 on the treated water outlet 20 side is opened. The other end of the hollow fiber membranes is integrally bonded to each other with an adhesive to form the lower ring side adhesive fixing layer 5, but the end of the hollow fiber membranes is sealed. In the lower ring side adhesive fixing layer 5, a plurality of through holes 8 for introducing raw water and cleaning gas into the hollow fiber membrane bundle and effectively contacting the outer peripheral surface of the hollow fiber membranes are formed.

The diameter of the hollow fiber membrane cartridge 18 is preferably 30mm to 800mm, more preferably 100mm to 800 mm. The length of the hollow fiber membrane cartridge is preferably in the range of 300mm to 3000 mm.

In the present invention, the filter element head side adhesive layer 4 and the lower ring side adhesive layer 5 are connected and fixed by the side core rod 11 serving as any one of a rod, a pipe, a plate, a chain, a rope, and a net for the purpose of preventing the lower ring from rising or twisting during aeration. Particularly, a rod or a tube is preferable, and the material used is preferably metal or resin. The shape of these rods or tubes is arbitrary, but it is preferable to be cylindrical, and a shape having acute angles is not suitable because it may cause damage when the hollow fiber membranes are repeatedly contacted. The thickness is preferably determined in consideration of the strength of deformation with respect to the material used. Further, when the hardness of the pipe or rod used for the connection is high, it is preferable to cover the surface with a resin or the like having low hardness, since damage of the hollow fiber membrane caused by repeated contact with the rod can be prevented.

The pore diameter of the hollow fiber membrane used in the present invention is not particularly limited, and any of reverse osmosis membranes, ultrafiltration membranes and microfiltration membranes can be used. The material of the hollow fiber membrane is not particularly limited, and examples thereof include polysulfone, polyethersulfone, polyacrylonitrile, polyimide, polyetherimide, polyamide, polyetherketone, polyetheretherketone, polyethylene, polypropylene, poly-4-methylpentene, cellulose acetate, poly-1, 1-difluoroethylene, polyethylene-tetrafluoroethylene copolymer, and polytetrafluoroethylene. Or composite raw material films thereof may be used. Further, as the shape of the hollow fiber membrane, a membrane having an inner diameter of 50 μm to 3000 μm and an inner/outer diameter ratio of 0.3 to 0.8 is suitably used.

The core-side adhesive layer and the lower ring-side adhesive layer of the hollow fiber membrane filter element according to the present invention are made of an adhesive composed of the following materials. Examples of the adhesive include polymer materials such as epoxy resin, urethane resin, epoxy acrylic resin, and silicone resin.

The resin hardness of the filter part interface of the filter element head side and the lower ring side adhesive fixing layer is preferably 20A or more and 90A or less, more preferably 20A or more and 70A or less (the resin hardness is measured by jis k6253 and ISO7619, the same applies to the description below in this specification). If the amount is less than 20A, the hardness is insufficient and the shape cannot be maintained for a long period of time. If the ratio is more than 90A, the deformation stress of the hollow fiber membrane during oscillation cannot be relaxed, and the hollow fiber membrane may be broken. Thus, in addition to using a resin of low hardness as an adhesive, by bonding a resin of low hardness on the anchor layer bonded at the first stage, it is possible to adjust the resin hardness of the desired interface. For example, the resin hardness of the interface can be adjusted by bonding a silicone resin to an epoxy resin after forming an adhesive layer with an epoxy resin, or bonding a urethane resin having a low hardness to a urethane resin after forming an adhesive layer with a urethane resin. As the bonding method, a known method such as a centrifugal bonding method or a static bonding method can be used. When the curing shrinkage and strength of the adhesive are to be improved, the adhesive may contain a fibrous material such as glass fiber or carbon fiber, or fine powder such as carbon black, alumina or silica.

The materials of the filter element head 2 and the lower ring 3 used in the present invention are not particularly limited, and may be the same or different, but it is preferable to use a thermoplastic resin or stainless steel. The filter element head 2 is also a fixing portion when the hollow fiber membrane filter element 18 is hung in the container, and therefore the shape of the filter element head is manufactured in accordance with the hanging/fixing structure. For example, a step or a groove may be provided in the outer peripheral portion, or a screw groove may be provided. The suspension system into the vessel includes a tank system fixed to a partition plate separating the tank into upper and lower parts, a net rack system fixed to a main pipe branching from a main pipe, and the like, and the filter element of the present invention can be suitably applied to any of them.

The through-hole 8 provided in the lower ring side adhesive-fixing layer 5 is a hole provided in the adhesive-fixing layer itself, and the size of the through-hole is preferably in the range of 2mm to 30mm in equivalent diameter. The shape of the through-hole may be any of triangular, quadrangular, hexagonal, polygonal, circular, elliptical, fan-shaped, C-shaped, star-shaped, and the like. The number of the holes depends on the cross-sectional area of the filter element and the number of the filament membranes, but it is preferable that the number of the openings is 2 to 300. The through holes may be located at intersections of multiple circles and radial lines, intersections of lattices, or positions of vertices of multiple regular triangles in the cross section of the adhesive layer, and are preferably evenly distributed in the cross section of the adhesive layer.

In the present invention, the lower ring 3 preferably protrudes downward from the end face of the lower ring side adhesive layer and is fixed to the outer periphery of the hollow fiber membrane bundle, as shown in the drawing as the lower ring end 9. The length of the protrusion from the end face depends on the diameter of the filter element, the amount of gas to be supplied, and the diameter and number of the through holes, but is preferably 5mm to 300mm in order to prevent the gas from escaping from below. When the thickness is 300mm or less, the amount of useless space is small over the entire length of the filter element, and therefore, it is preferable. When the thickness is 5mm or more, the gas supplied to the filter element is effectively introduced into the through-holes and does not escape in the lateral direction, which is preferable.

In order for the gas ejected from the aeration gas ejection ports 19 to uniformly pass through the plurality of through holes 8 in the lower ring-side adhesive/fixing layer 5, it is necessary to form gas staying portions in the space protruding downward on the lower ring 3 in the gas ejected from the aeration gas ejection ports 19 and supply the gas from the gas staying portions to the through holes. The thickness of the gas retention portion is preferably not less than 30mm, more preferably not less than 50 mm. The position of the aeration gas ejection port 19 is preferably determined in consideration of the thickness of the gas staying portion to be formed. An aeration gas introduction pipe 21 is connected to the aeration gas discharge port 19, and bubbles are supplied into a space protruding downward from the lower ring 3.

The arrangement of the hollow fiber membrane bundles 1 in the filter unit interface 13 of the filter element head side adhesive-fixing layer of the present invention may be irregular as in (a) as shown in the example of fig. 3, but it is preferable to arrange the hollow fiber membrane bundles concentrically as in (b). The shape of the hollow fiber membrane bundle may be other than circular as in (c) and (d). The size of the hollow fiber membrane bundle may be different as in (d) and (e).

It is preferable that a portion where no hollow fiber membrane is disposed is provided in the center of the filter section interface 13 of the filter element head side adhesive fixing layer. Thus, the gas passing through the through-hole 8 of the lower ring side adhesive fixing layer 5 hardly escapes to the outer peripheral portion of the filter element before reaching the vicinity of the filter element head 2, and also escapes to the outer peripheral portion in the vicinity of the filter element head, so that the adhesion of sludge in the vicinity of the filter element head to which sludge is likely to adhere can be prevented.

The following describes examples of the present invention, but the present invention is not limited thereto.

(example 1)

A hollow fiber membrane cartridge was produced by bonding and fixing both ends of a plurality of hollow fiber membranes with a urethane resin, having a cartridge head bonded and fixed to the outer periphery of one end portion in a liquid-tight manner and a lower ring bonded and fixed to the outer periphery of the other end portion in a liquid-tight manner, and having a membrane area of 25m²The cylindrical hollow fiber membrane cartridge of (1). The hollow fiber membrane is a polyvinyl fluoride-containing microfiltration membrane with pore diameter of 0.1 μm, and has an outer diameter of 1.4mm, an inner diameter of 0.8mm, and filter core head side and lower ring side adhesive fixing layersThe effective length between the filter house interfaces was 2000 mm. The diameter of the adhesive fixing layer at both ends of the hollow fiber membrane was about 150 mm.

The hollow fiber membranes were bundled into one bundle of 1100 hollow fiber membranes per 1 bundle on the filter unit interface of the filter element head side adhesive-fixing layer, and the number of bundles was 3 bundles, and the hollow fiber membranes were arranged as shown in fig. 4 (a). The beamlets are spaced 3mm from each other. In order to arrange the small bundles as shown in fig. 4(a), a porous plate having holes formed in a resin plate is prepared, the porous plate is installed inside the filter element head, and the small bundles are fixed in the filter element head through the porous plate and then bonded. On the other hand, the lower ring side is bonded and fixed with the hollow fiber membranes in a single bundle. At this time, 24 through holes having a diameter of 11mm were opened in the hollow fiber membrane bundle. The polyurethane resin (SA-6330 series, manufactured by サンユレツク Co., Ltd., hardness after curing: 98A) was used for bonding, and after centrifugal bonding, the polyurethane resin (SA-6330 series, manufactured by サンユレツク Co., Ltd., hardness after curing: 56A) was fixed to the interface between the bonded portion and the non-bonded portion of the hollow fiber membrane by static bonding.

In the centrifugal bonding, the filter element head side adhesive layer and the lower ring side adhesive layer were fixedly connected to each other by 2 pipes each of which was made of SUS304 and made of a film made of ビニリデン and covered with a pipe having an outer diameter of 13 mm.

An aeration gas introduction pipe was inserted from the side surface of the lower ring, and an aeration gas injection port having a diameter of 2cm was provided in the horizontal direction at a lower portion 20cm below the lower ring-side adhesive/fixing layer and substantially in the center of the lower ring.

The membrane separation device of the present invention was immersed in 8m³The filter element head and the filtered water piping are connected and fixed in the activated sludge tank.

While exposing 6Nm from the aeration gas introduction pipe to the membrane separation apparatus of the present invention³Air/hr, one side of the membrane filtration flow is 0.6m³Area m of membrane²Day/day suction filtration was performed with a suction pump. At this timeThe pressure difference between membranes is-15 to-20 kPa, and the pressure difference is kept stable for 3 months. The concentration MLSS of the activated sludge tank during the evaluation was 10000mg/l on average and the average temperature was 25 ℃. The raw water of the activated sludge was urban sewage having an average BOD of 150mg/l and SS of 160 mg/l.

The weight of sludge deposit and foreign matter attached to the filter element after 3 months of operation was 3.23kg, indicating that the amount of deposit was small. The weight is measured before and after the use of the hollow fiber membrane in a wet state, and the weight difference is defined as the weight of sludge deposit or inclusion.

(example 2)

The membrane separation apparatus was produced by bundling 110 hollow fiber membranes per 1 bundle at the filter unit interface of the adhesive fixing layer on the filter element head side, and setting the number of bundles to 30 and the interval between bundles to 1.5 mm. The procedure was as in example 1 except that the arrangement was performed as shown in FIG. 4 (b).

In addition, the operation was carried out by immersing the activated sludge in the same manner as in example 1, and the pressure difference between membranes was-15 to-20 kPa, and the pressure was kept stable for 3 months. The weight of sludge deposit and foreign matter attached to the filter element after 3 months of operation was 2.53kg, indicating that the amount of deposit was small.

(example 3)

The membrane separation apparatus was produced by bundling 110 hollow fiber membranes per 1 bundle at the filter unit interface of the adhesive fixing layer on the filter element head side, and setting the number of bundles to 30 and the interval between bundles to 2.0 mm. The same as in example 1 except that the arrangement was performed as shown in FIG. 4 (c).

In addition, the operation was carried out by immersing the activated sludge in the same manner as in example 1, and the pressure difference between membranes was-15 to-20 kPa, and the pressure was kept stable for 3 months. The weight of sludge deposit and foreign matter attached to the filter element after 3 months of operation was 2.03kg, indicating that the amount of sludge deposit was small.

(example 4)

The membrane separation apparatus was produced by bundling 110 hollow fiber membranes per 1 bundle at the filter unit interface of the adhesive fixing layer on the filter element head side, and setting the number of bundles to 30 and the interval between bundles to 3.0 mm. The same as in example 1 except that the arrangement was performed as shown in FIG. 4 (d).

In addition, the operation was carried out by immersing the activated sludge in the same manner as in example 1, and the pressure difference between membranes was-15 to-20 kPa, and the pressure was kept stable for 3 months. The weight of sludge deposit and foreign matter attached to the filter element after 3 months of operation was 1.23kg, indicating that the amount of deposit was small.

(example 5)

The membrane separation apparatus was produced by bundling 110 hollow fiber membranes per 1 bundle at the filter unit interface of the adhesive fixing layer on the filter element head side, setting the number of bundles to 30 and the interval between bundles to 3.0mm, and arranging the bundles on a concentric circle. The procedure was repeated as in example 1 except that the arrangement was carried out as shown in FIG. 4 (e).

The operation was carried out by immersing the activated sludge in the same manner as in example 1, and the pressure difference between membranes was-15 to-20 kPa, and the pressure was maintained stably for 3 months. The weight of sludge deposit and foreign matter attached to the filter element after 3 months of operation was 0.56kg, indicating that the amount of sludge deposit was small.

(example 6)

A membrane separation device was produced in which the hollow fiber membranes were bundled into one bundle of 110 hollow fiber membranes per 1 bundle on the filter unit interface of the adhesive fixing layer on the filter element head side, the number of bundles was set to 30, the interval between bundles was set to 3.0mm, and the bundles were arranged on a concentric circle and arranged so that the bundles were present in all circumferential directions from the center of the filter element head (fig. 4 (f)). Except for the arrangement, the same as example 1.

In addition, the operation was carried out by immersing the activated sludge in the same manner as in example 1, and the pressure difference between membranes was-15 to-20 kPa, and the pressure was kept stable for 3 months. The weight of sludge deposit and foreign matter attached to the filter element after 3 months of operation was 0.52kg, indicating that the amount of sludge deposit was extremely small.

Comparative example 1

A membrane separation apparatus was produced in which the activated sludge tank was operated and evaluated under the same filtration conditions as in example 1 except that the arrangement of the hollow fiber membranes at the filtration section interface of the filter element head side adhesive-fixing layer was made into a single bundle structure without being divided into small bundles as shown in fig. 4 (g).

At this time, the pressure difference between the membranes rapidly increased within 14 days, and after reaching-80 kPa, the suction by the pump was impossible. As in example 1, the concentration MLSS of the activated sludge tank after 3 months of the operating period was 10000mg/l on average and the average temperature was 25 ℃. As the raw water of activated sludge, as in example 1, urban sewage having an average BOD of 150mg/l and SS of 160mg/l was used.

The weight of sludge deposit and foreign matter attached to the filter element after operation was 10.1kg, indicating that the deposit weight was significantly large.

Industrial applicability of the invention

The hollow fiber membrane cartridge of the present invention is used by being attached to a pressurized or suction box-type filtration device or a submerged filtration device. More specifically, the hollow fiber membrane cartridge of the present invention is used in a filtration apparatus for removing turbidity and bacteria from raw water such as river water, lake water, underground water, sea water, domestic drainage, factory drainage, secondary sewage treatment water, or in a membrane separation activated sludge apparatus for performing solid-liquid separation of activated sludge using a membrane.

Claims (8)

1. A hollow fiber membrane cartridge comprising 1 or more hollow fiber membrane bundles each composed of a plurality of hollow fiber membranes and having both ends adhesively fixed to each other by an adhesive layer, a cartridge head liquid-tightly fixed to the outer periphery of one end of the hollow fiber membrane bundle, and a lower ring fixed to the outer periphery of the other end, wherein:

the hollow portion of the hollow fiber membrane is opened at the end portion of the filter element head side, the hollow portion of the hollow fiber membrane is sealed in the lower ring side adhesive fixing layer, a plurality of through holes are provided in the lower ring side adhesive fixing layer, the through holes are arranged in the hollow fiber membrane bundle, the end portion of the lower ring is more protruded than the end face of the lower ring side adhesive fixing layer, and at least a part of the hollow fiber membrane bundle is divided into a plurality of small bundles of 2 or more at the filter element head side adhesive fixing layer.

2. The hollow fiber membrane cartridge according to claim 1, wherein the at least a part of the hollow fiber membrane bundles are divided into a plurality of bundles of 2 or more pieces on the way from the lower ring side adhesive layer to the cartridge head side adhesive layer.

3. The hollow fiber membrane cartridge according to claim 1, wherein the bundles of hollow fiber membranes on the filter section interface of the cartridge head side adhesion fixing layer, in each bundle, the distance between the nearest hollow fiber membranes is less than 2mm, the number of hollow fiber membranes is 10 or more and 1000 or less; the distance between the nearest small beams is more than or equal to 2mm and less than or equal to 100 mm.

4. The hollow fiber membrane cartridge according to claim 1, wherein the bundles of hollow fiber membranes at the filter section interface of the cartridge head side adhesive-fixing layer are arranged on 1 or more concentric circles.

5. The hollow fiber membrane cartridge according to claim 4, wherein the hollow fiber membrane bundle is present in all directions from a center portion to an outer peripheral portion of a concentric circle of the filter portion interface of the cartridge head side adhesion fixing layer.

6. The hollow fiber membrane cartridge according to claim 1, wherein the resin forming the filter portion interface of the cartridge head side and the lower ring side adhesive fixing layers has a hardness of 20A or more and 90A or less as measured in accordance with JISK6253 and ISO 7619.

7. A membrane separation apparatus wherein a hollow fiber membrane cartridge according to any one of claims 1 to 6 is vertically arranged in a vessel having an inflow port, and a gas introduction port for ejecting a gas for oscillating the hollow fiber membrane during filtration and/or backwashing through a plurality of through holes in a lower ring-side adhesive fixing layer is provided below a lower ring of the hollow fiber membrane cartridge.

8. A membrane separation method wherein raw water to be treated is introduced into a vessel, and suction filtration and backwashing are performed while aeration is performed from below the lower ring of the hollow fiber membrane cartridge according to any one of claims 1 to 6 arranged in the vertical direction in the vessel.