JP5281254B2 - Hollow fiber membrane module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a clogging in a module case suppressing a mutual entanglement of hollow fiber membranes in a hollow fiber membrane module in which the lower end of a hollow fiber membrane bundle housed in the module case is made a fixed end, and at the same time, the upper end is made a free end. <P>SOLUTION: The hollow fiber membrane 12 is doubled as a pair of hollow fiber membranes 12A, a plurality of pairs of hollow fiber membranes 12A are bundled in the same direction to make a hollow fiber membrane bundle 11, at the same time, to make the end side of the hollow fiber membrane 12 in a pair of the hollow fiber membranes 12A as the fixed end side, and the folded side of the hollow fiber membrane 12 as the free end side, and the range of a predetermined length from the free end in the hollow fiber membrane bundle 11 is taken out outside the module case 13. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a hollow fiber membrane module suitable for a water treatment apparatus that performs sewage treatment such as domestic wastewater and industrial wastewater.

Conventionally, highly treated water such as sewage is stored in a water tank together with activated sludge, and a hollow fiber membrane module is immersed in the water to be treated and aerated in the water tank. There is known a membrane separation activated sludge method for solid-liquid separation of water into sludge and treated water.
The hollow fiber membrane module includes a hollow fiber membrane bundle formed by bundling a plurality of hollow fiber membranes and a module case that opens both ends in the longitudinal direction, and the longitudinal direction of the hollow fiber membrane bundle is in the longitudinal direction. It is accommodated in the module case so that the lower end of the bundle of hollow fiber membranes is a fixed end and the upper end is a free end, thereby adhering to the hollow fiber membrane (fine fibrous waste in waste water) Is easily removed on the free end side (see, for example, Patent Documents 1 and 2).
Japanese Patent Laid-Open No. 11-128692 JP-A-11-342321

By the way, the hollow fiber membrane module has a problem that the hollow fiber membranes are easily entangled with each other during operation of the water treatment apparatus. When hollow fiber membranes are entangled with each other, the residue in the water to be treated is likely to be entangled with the part, and the entangled residue and the like are separately attached and accumulated with dirt and activated sludge in the water. There is a problem that clogging in the case is induced, the flow of water to be treated is hindered, and the water treatment performance is lowered.
Therefore, the present invention provides a hollow fiber membrane module in which the lower end of the bundle of hollow fiber membranes accommodated in the module case is a fixed end and the upper end is a free end. The purpose is to prevent clogging.

  As a means for solving the above problems, the invention described in claim 1 includes a hollow fiber membrane bundle formed by bundling a plurality of hollow fiber membranes, and a module case that opens both ends in the longitudinal direction. The hollow fiber membrane module is housed in the module case so that its longitudinal direction is along the longitudinal direction, and the hollow fiber membrane is folded in half in a hollow fiber membrane module having the lower end of the hollow fiber membrane bundle as a fixed end and the upper end as a free end. A hollow fiber membrane pair, and a plurality of the hollow fiber membrane pairs are bundled in the same direction to form the hollow fiber membrane bundle, and the end side of the hollow fiber membrane in the hollow fiber membrane pair is the fixed end side, and the hollow The return side of the yarn membrane is the free end side, and a range of a predetermined length from the free end of the hollow fiber membrane bundle is provided outside the module case.

  The invention described in claim 2 is characterized in that a cross-sectional area of the internal space of the module case in a cross section substantially perpendicular to the vertical direction of the module case changes with the vertical position.

  The invention described in claim 3 is characterized in that the folded portion of the hollow fiber membrane in the hollow fiber membrane pair has hydrophobicity.

According to the present invention, the hollow fiber membranes are folded in half to form a hollow fiber membrane pair, and the folded portion is arranged on the free end side so that the hollow fiber membranes that are paired by the looped bent portions are separated from each other. The entanglement of the hollow fiber membranes due to the suction of the hollow fiber membranes and the attraction of the hollow fiber membranes with an increase in the rising flow rate of the water to be treated is suppressed. As a result, entanglement of residue and the like on the hollow fiber membrane is suppressed and the density of the hollow fiber membrane bundle is also suppressed, so that clogging in the module case is prevented and the water treatment performance can be kept good. .
In addition, since the folded portion that is relatively entangled with the residue etc. is provided outside the module case, even if the residue is entangled with the folded portion, this does not cause clogging in the module case. Residues and the like are easily removed on the swirling flow of the water to be treated in the water tank.

Furthermore, since the cross-sectional area of the internal space of the module case changes with the position in the vertical direction, it becomes easy to cause turbulent flow in the upward flow of the water to be treated in the module case, and the scrubbing effect by aeration can be enhanced.
In addition, by making the folded portion of the hollow fiber membrane pair hydrophobic, even when air is mixed into the hollow fiber membrane, the air can easily escape from the folded portion which is the upper end portion of the hollow fiber membrane pair to the outside of the membrane. Thus, an increase in pump load due to air biting can be prevented.

  Embodiments of the present invention will be described below with reference to the drawings. For convenience of explanation, the arrow FR indicates the front, the arrow LH indicates the left side, and the arrow UP indicates the upper side.

  A water treatment apparatus 1 shown in FIG. 1 is used for sewage treatment of domestic wastewater, industrial wastewater, and the like. A hollow fiber membrane module 10 is immersed in a water tank 2 storing treated water W, and the hollow fiber membrane module is obtained. By sucking the 10 permeate side with the pump 4, the water to be treated is separated into activated sludge for wastewater treatment and treated water. In the aquarium 2, aeration for breeding activated sludge, which is an aerobic microorganism, is performed, and the swirling flow of the water to be treated W generated in the aquarium 2 by the aeration is used to form the hollow fiber membrane module 10. The dirt attached to the membrane surface of the hollow fiber membrane 12 is scraped off.

  2 and 3 together, the hollow fiber membrane module 10 has a thick plate-like appearance that rises in the vertical direction, and has a vertically long rectangular shape in front view (front view). The hollow fiber membrane module 10 includes a hollow fiber membrane bundle 11 formed by bundling a plurality of hollow fiber membranes 12, and a module case 13 that opens both ends (upper and lower ends) in the longitudinal direction. The basic structure is accommodated in the module case 13 with its longitudinal direction being along the vertical direction (vertical direction). The lower end of the hollow fiber membrane bundle 11 is a fixed end whose oscillation is restricted with respect to the module case 13, and the upper end of the hollow fiber membrane bundle 11 is a free end that can freely swing with respect to the module case 13. Is done.

The hollow fiber membrane bundle 11 is a fixed portion 14 whose lower end is integrated into a block shape via a potting resin 14a. A lower end opening of each hollow fiber membrane 12 faces the lower surface of the fixing portion 14, and the inside of each hollow fiber membrane 12 is opened downward (not shown). The fixing portion 14 is liquid-tightly attached to the hollow water collector 15 using the same potting resin 14a, and allows the inside of the water collector 15 and the inside of each hollow fiber membrane 12 to communicate with each other. The water intake port 15a of the water collector 15 is connected to the pump 4 via the water guide path 5 (see FIG. 1), and the operation of the pump 4 creates a pressure difference on the membrane surface of each hollow fiber membrane 12, In the hollow fiber membrane 12, treated water obtained by solid-liquid separation of activated sludge and the like from the treated water W is obtained.
A lower end of a module case 13 that forms the appearance of the hollow fiber membrane module 10 is attached to the water collector 15, and the integrated hollow fiber membrane module 10 is constituted by the water collector 15, the module case 13, and the hollow fiber membrane bundle 11. Is configured.

  Examples of the material of the hollow fiber membrane 12 include those made of various materials such as polyolefin, cellulose, polyvinyl alcohol, polysulfone, polymethyl methacrylate, polyvinylidene fluoride, polyfluorinated ethylene, polyacrylonitrile, ceramics, and composites thereof. . As long as the hollow fiber membrane 12 can be used as a filtration membrane, there are no particular limitations on the pore diameter, porosity, film thickness, outer diameter, and the like.

  The water collector 15 may be made of any material as long as it has durability against the water to be treated W and can withstand the pressure during the filtration treatment. For example, polycarbonate, polysulfone, polyolefin, modified polyphenylene ether, ABS resin, poly Examples include vinyl chloride.

  As the potting resin 14a, each hollow fiber membrane 12 is fixed to the water collector 15, and the treated water W and the treated water that has passed through the hollow fiber membrane 12 are partitioned liquid-tightly, If there is no problem in durability at the time of use, there is no limitation, and examples thereof include thermosetting resins such as epoxy resins, urethane resins, unsaturated polyester resins, silicone resins, and various thermoplastic resins.

  As shown in FIG. 1, the hollow fiber membrane module 10 is fixed in the upright state on a gantry 3 erected on the bottom of the water tank 2. Inside the gantry 3, an air diffuser 6 that generates foam-like aerated air B in the water tank 2 is disposed. The air diffuser 6 is connected to a blower (blower) 8 through an air supply path 7, and when the aeration air B is supplied into the module case 13 of the hollow fiber membrane module 10 by the operation of the blower 8, the aeration As the air B rises, an upward flow of the water to be treated W is generated in the module case 13 and the dirt adhering to the membrane surface of each hollow fiber membrane 12 is scraped off, and the adhering residue (fine fibrous form in the wastewater) Etc.) are removed on the upper end side (free end side) of the hollow fiber membrane 12. In addition, the arrow R in FIG. 1 shows the swirl | vortex flow of the to-be-processed water W which arises in the water tank 2 with the said upward flow.

Here, FIG. 3 shows an example of the configuration of the hollow fiber membrane module 10 of the present invention. The hollow fiber membrane bundle 11 is configured by folding a single hollow fiber membrane 12 into two to form a hollow fiber membrane pair 12A and bundling a plurality of the hollow fiber membrane pairs 12A in the same direction. The end side of the hollow fiber membrane 12 in the hollow fiber membrane pair 12A is located on the lower end side, that is, the fixed end side of the hollow fiber membrane bundle 11, and the folded side of the hollow fiber membrane 12 in the hollow fiber membrane pair 12A is the hollow fiber membrane bundle. 11 is located on the upper end side, that is, on the free end side. Hereinafter, the end portion of the hollow fiber membrane 12 in the hollow fiber membrane pair 12A is referred to as a terminal portion (not shown), and the end portion on the folded side of the hollow fiber membrane 12 is referred to as a folded portion 12b.
In the folded portion 12b of the hollow fiber membrane 12, one hollow fiber membrane 12 may be folded in half, or a small bundle of a plurality of hollow fiber membranes 12 may be folded in half. The number of these hollow fiber membranes 12 is preferably 10 or less, and more preferably 5 or less, in order to improve the detergency between the hollow fiber membranes 12.

  The end portion of the hollow fiber membrane pair 12A is fixed so as not to swing at the fixing portion 14, and the folded portion 12b of the hollow fiber membrane pair 12A can freely swing without being restricted by anything. . The folded portion 12b has an inverted U-shape (loop shape) that opens to the end portion side (fixed end side), and between the hollow fiber membranes 12 arranged in parallel in one hollow fiber membrane pair 12A or the above-mentioned It acts so as to separate the small bundles of the hollow fiber membranes 12, thereby suppressing the entanglement between the hollow fiber membranes 12 over the entire length thereof.

Here, the upper end side of the hollow fiber membrane bundle 11 has a predetermined length range (corresponding to a protrusion amount L2 described later, see FIG. 5) from the folded portion 12b, and the module case 13 from the upper end opening of the module case 13. It protrudes outside (above the upper end opening). As a result, the residue or the like that has moved to the free end side of the hollow fiber membrane bundle 11 along with the rising flow of the water to be treated W rides on the swirling flow of the water to be treated W and is on the outer peripheral side (outside in the horizontal direction) ) Is easily removed.
That is, in the folded portion 12b that is relatively easy to entangle the residue etc., it is difficult for the residue or the like to be entangled, and even if entangled, the periphery of the folded portion 12b is arranged outside the module case 13 so The water treatment apparatus 1 can be stably operated over a long period without causing clogging.

  By the way, since the hollow fiber membrane 12 performs filtration in water, it is known that the surface is hydrophilic. At the time of maintenance of the hollow fiber membrane module 10 after filtration in water, the hollow fiber membrane module 10 is once pulled up on the water, checked, and then immersed in water again with the membrane surface of the hollow fiber membrane 12 wet. At this time, air is likely to be mixed into the hollow fiber membrane 12. If the operation of the water treatment apparatus 1 is resumed in this state, an excessive force for sucking the treated water by the pump 4 may be required.

  Therefore, in the hollow fiber membrane module 10 of the present invention, only the folded portion 12b, that is, the upper end portion of the hollow fiber membrane pair 12A is made hydrophobic. For this reason, when the hollow fiber membrane module 10 once raised on water as described above is immersed again in water, the air in the membrane easily escapes from the hydrophobic upper ends of the hollow fiber membrane pair 12A, and the water treatment The operation restart of the device 1 is facilitated. There are various methods for imparting hydrophobicity to the folded portion 12b. Among them, a simple method is to apply a hydrophobic resin to the folded portion 12b. Examples of the hydrophobic resin include known urethane resins, silicone resins, and epoxy resins.

  As shown in FIG. 4A, the module case 13 has a cross-sectional area of its internal space in the longitudinal direction (vertical direction), that is, in a cross section (horizontal cross section) orthogonal to the longitudinal direction of the hollow fiber membrane 12. Change with. Specifically, for example, a narrowed portion 13 a that narrows the dimension (for example, the front-rear thickness) of the internal space in the vertical direction intermediate portion of the module case 13 is provided. As a result, turbulent flow is likely to occur in the water to be treated W that rises together with the aerated air B, and the removal performance of dirt, residue, etc. adhering to the membrane surface of the hollow fiber membrane 12 is improved. In addition, the structure provided with two or more aperture | diaphragm | squeeze parts 13a may be sufficient.

FIG.4 (b) shows the hollow fiber membrane module 110 which has a cylindrical external appearance standing along an up-down direction. The hollow fiber membrane module 110 has a basic configuration in which a hollow fiber membrane bundle 111 is accommodated in a module case 113. The lower end of the hollow fiber membrane bundle 111 is a fixed end, and the upper end of the hollow fiber membrane bundle 111 is a free end. The fixing portion 114 below the hollow fiber membrane bundle 111 is attached to a hollow disk-shaped water collector 115, and a water inlet 115 a of the water collector 115 is connected to the pump 4 through the water guide path 5. The hollow fiber membrane bundle 111 is also configured by bundling a plurality of the hollow fiber membrane pairs 12A.
Also in the module case 113 that forms the appearance of the hollow fiber membrane module 110, for example, a narrowed portion 113a that narrows the lateral width of the internal space may be provided in the middle portion in the longitudinal direction.

Hereinafter, an embodiment of the hollow fiber membrane module 10 of the present invention will be shown.
[Configuration overview]
About 800 hollow fiber membranes 12 made of PVDF (polyvinylidene fluoride) having an outer diameter of 2.8 mm and an effective length of 1300 mm were prepared.
The module case 13 was made of PVC, having a vertical height of 1000 mm, a horizontal width of 550 mm, a front and rear thickness of 45 mm, and an outer wall plate thickness of 3 mm.
The water collector 15 was made of ABS, and had a vertical height of 75 mm, a horizontal width of 650, and a front and rear thickness of 30.

[Production of hollow fiber membrane module]
First, after each hollow fiber membrane 12 is folded in half (or for each small bundle) to form a hollow fiber membrane pair 12A, a predetermined number of hollow fiber membrane pairs 12A have a pitch of 3 between the hollow fiber membranes 12. A sheet-like film body is formed by, for example, arranging 2 mm so as to be knitted with a yarn for temporary fixing.
Five sheets of this sheet-like membrane body are prepared and stacked to form a hollow fiber membrane bundle 11, and the lower end side (the end side of the hollow fiber membrane 12 in the hollow fiber membrane pair 12A) is placed in the resin container for forming the fixing portion 14. The resin container is filled with a potting resin 14a such as urethane.
Then, by cutting the cured potting resin 14a to a predetermined thickness, the fixing portion 14 in which the lower end portion of the hollow fiber membrane bundle 11 is integrated into a block shape is formed, and each hollow fiber is formed on the lower surface of the fixing portion 14. The end face of the film 12 is opened.

The fixing portion 14 is inserted into the water collector 15, and the potting resin 14 a is filled in the water collector 15 to be cured. Thereafter, the fixed yarn is removed, the module case 13 is covered with the hollow fiber membrane bundle 11, and the lower end thereof is partially fixed to the water collector 15 by adhesion or the like, so that the integral hollow fiber membrane module 10 can be manufactured. Complete.
A gap for passing aeration air B is appropriately formed in the module case 13. The thickness of the module case 13 is larger than the thickness of the water collector 15, and the aeration air B from the diffuser 6 is generated from the gap between the water collector 15 and the lower end of the module case 13. It is supplied into the module case 13 together with the water to be treated W. The scrubbing effect in the module case 13 scrapes off the dirt on the membrane surface of the hollow fiber membrane bundle 11 and removes adhering residue and the like.

[Confirmation of aeration status]
Three hollow fiber membrane modules 10 are prepared, and are fixed on the gantry 3 in the water tank 2 in a state in which these are arranged without gaps in the front-rear thickness direction. By arranging the hollow fiber membrane modules 10 without gaps, the aeration air B supplied from below is easily supplied into the module case 13.
The treated water W and activated sludge are stored in the water tank 2, the hollow fiber membrane module 10 is immersed in the treated water W, and the air diffuser 6 is immersed in activated sludge precipitated at the bottom of the water tank 2. Then, the blower 8 is operated to supply air at 10 m ³ / min to start aeration, and the pump 4 is operated to start suction filtration of the treated water W.
One week later, no abnormality was found in the operation status of the water treatment apparatus 1. Moreover, when the hollow fiber membrane module 10 was pulled up on the water and the accumulation state of residue etc. was confirmed, some residue accumulation was seen in the folded part 12b of the hollow fiber membrane pair 12A. The clearance (flow path of aeration air B) between the module case 13 and the hollow fiber membrane bundle 11 was ensured.

  As shown in FIG. 5, in the hollow fiber membrane module 10 immersed in the water to be treated W, between the upper end (the upper end of the hollow fiber membrane bundle 11 protruding above the module case 13) and the water surface of the water W to be treated. The distance L1 is at least 10 mm or more. This is because when the distance L1 is less than 10 mm, the water that has reached the upper side of the module case 13 due to aeration is less likely to flow to the outer peripheral side of the module case 13 and the swirl flow in the water tank 2 is less likely to occur. This is because the upward flow in 13 is also inhibited. In order to stably obtain the swirling flow in the water tank 2, the distance L1 is preferably 100 mm or more, more preferably 300 mm or more.

  Further, the protruding amount of the hollow fiber membrane bundle 11 from the upper end of the module case 13 (distance between the upper end of the module case 13 and the folded portion 12b) L2 is the folded amount even when a residue or the like adheres to the folded portion 12b. In order to ensure the flow path of the to-be-processed water W between the part 12b and between the folding | returning part 12b and the module case 13, at least 10 mm or more is ensured. Moreover, in order to ensure the said flow path for a long term, the said protrusion amount L2 has preferable 30 mm or more. The protrusion amount L2 is 500 mm or less, preferably 300 mm or less. This is because, when the protruding amount L2 is excessively large, the hollow fiber membrane 12 protruding from the module case 13 rides on the swirling flow in the water tank 2 and curves downward on the outer peripheral side of the module case 13, and the intermediate portion thereof This is because it is considered that the module case 13 is worn and damaged due to contact with the corner of the upper end of the module case 13.

  As described above, the hollow fiber membrane module 10 in the above embodiment includes the hollow fiber membrane bundle 11 formed by bundling a plurality of hollow fiber membranes 12 and the module case 13 that opens both ends in the longitudinal direction. A thread membrane bundle 11 is accommodated in the module case 13 so that its longitudinal direction is along the longitudinal direction, and the lower end of the hollow fiber membrane bundle 11 is a fixed end and the upper end is a free end. Alternatively, the plurality of hollow fiber membranes 12 are folded in half to form a hollow fiber membrane pair 12A, and a plurality of the hollow fiber membrane pairs 12A are bundled in the same direction to form the hollow fiber membrane bundle 11, and in the hollow fiber membrane pair 12A The end side of the hollow fiber membrane 12 is the fixed end side, the folded side of the hollow fiber membrane 12 is the free end side, and a range of a predetermined length from the free end of the hollow fiber membrane bundle 11 is the module case. 3 of those you put on the outside.

According to this configuration, the hollow fiber membrane 12 is folded in half to form a hollow fiber membrane pair 12A, and the folded portion 12b is arranged on the free end side, so that the folded portion 12b that is curved in a loop shape forms a pair. Entanglement of the hollow fiber membranes 12 by acting so as to separate the membranes 12 from each other and attracting the hollow fiber membranes 12 to each other or attracting the hollow fiber membranes 12 with each other as the rising flow rate of the water to be treated W increases. Suppress. As a result, the entanglement of residue etc. on the hollow fiber membrane 12 is suppressed and the density of the hollow fiber membrane bundle 11 is also suppressed, so that clogging in the module case 13 is prevented and the water treatment performance is kept good. be able to.
In addition, since the folded portion 12b, which is relatively entangled with the residue, is provided outside the module case 13, even if the residue is entangled with the folded portion 12b, this does not cause clogging in the module case 13. In addition, the residue and the like are easily removed on the swirling flow of the water to be treated W in the water tank 2.

  Further, in the hollow fiber membrane module 10, the cross-sectional area of the internal space of the module case 13 in a cross section substantially orthogonal to the vertical direction of the module case 13 varies with the position in the vertical direction. It becomes easy to raise | generate a turbulent flow in the upward flow of the to-be-processed water W, and can improve the scrubbing effect by aeration.

  Further, in the hollow fiber membrane module 10, the folded portion 12b of the hollow fiber membrane 12 in the hollow fiber membrane pair 12A has hydrophobicity, so that even when air is mixed into the hollow fiber membrane 12, Air can easily escape from the folded portion 12b which is the upper end portion of the hollow fiber membrane pair 12A to the outside of the membrane, and an increase in pump load due to air biting can be prevented.

In addition, this invention is not restricted to the said Example, For example, it is good also as a structure which provided the air supply port in the outer wall of a module case instead of the structure which takes in aeration air in a module case from the downward direction. At this time, the air supply port may also serve as an inlet for the water to be treated into the module case.
And the structure in the said Example is an example of this invention, and it is not limited to the application to the water treatment apparatus for sewage treatment, Of course, a various change is possible in the range which does not deviate from the summary of the said invention. Needless to say.

It is a front view which shows the outline | summary of the water treatment apparatus in the Example of this invention. It is a perspective view of the hollow fiber membrane module used for the said water treatment apparatus. It is a perspective view which shows an example of the principal part of the said hollow fiber membrane module. It is a perspective view which shows the application example of the said hollow fiber membrane module, (a) shows a rectangular hollow fiber membrane module, (b) shows a cylindrical hollow fiber membrane module, respectively. It is a front view equivalent to FIG. 1 which shows the main dimensions which concern on the said hollow fiber membrane module.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Water treatment apparatus 10 Hollow fiber membrane module 11 Hollow fiber membrane bundle 12 Hollow fiber membrane 12A Hollow fiber membrane pair 12b Folding part 13 Module case

Claims (3)

A hollow fiber membrane bundle formed by bundling a plurality of hollow fiber membranes and a module case that opens both ends in the longitudinal direction, and the hollow fiber membrane bundle is placed in the module case so that the longitudinal direction thereof is along the longitudinal direction. In the hollow fiber membrane module containing the hollow fiber membrane bundle with the lower end as a fixed end and the upper end as a free end,
The hollow fiber membrane is folded in half to form a hollow fiber membrane pair, and a plurality of the hollow fiber membrane pairs are bundled in the same direction to form the hollow fiber membrane bundle, and the end side of the hollow fiber membrane in the hollow fiber membrane pair is A hollow fiber characterized in that a fixed end side, a folded side of the hollow fiber membrane is the free end side, and a range of a predetermined length from the free end of the hollow fiber membrane bundle is provided outside the module case. Membrane module.   2. The hollow fiber membrane module according to claim 1, wherein a cross-sectional area of the internal space of the module case in a cross section substantially orthogonal to the vertical direction of the module case varies with the position in the vertical direction. The hollow fiber membrane module according to claim 1 or 2, wherein a folded portion of the hollow fiber membrane in the hollow fiber membrane pair has hydrophobicity.

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