JP2005270944A - Hollow fiber membrane module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prepare a low-cost hollow fiber membrane module having inside it a water collecting body to provide the hollow fiber membrane module which serves as the water collecting body with superior liquid dispersion properties. <P>SOLUTION: This hollow fiber membrane module is made up of a cylindrical case, a large number of hollow fiber membranes housed in the case and one or more water collecting bodies. The ends of the hollow fiber membranes at both ends and, the hollow fiber membranes and the case are mutually sealed with resin, and internal pressure type filtration of filtering from the inside towards the outside of the hollow fiber membranes is made, and a net-like part is provided at a part at least of the water collecting bodies. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hollow fiber membrane module. More specifically, the present invention relates to an economical hollow fiber membrane module.

  Membranes that separate components in liquids and remove SS have been used for various applications because of energy saving. For example, industrial wastewater treatment, river water and groundwater turbidity, seawater desalination, bioreactors, etc. are examples. Various types of membranes have been used depending on the application. For example, river water is filtered through a microfiltration membrane, an ultrafiltration membrane, or a reverse osmosis membrane and used as drinking water. In the drainage, the activated sludge water is separated into activated sludge solids and filtered water by a microfiltration membrane or dynamic filtration.

  As modules used for such filtration, hollow fiber modules, spiral modules, tubular modules, plate and frames, immersion hollow fibers, flat membranes, and the like have been used. Among these, the hollow fiber membrane module has a large storage membrane area per volume and is widely used.

The usage can be adapted to any usage. In particular, hollow fiber membrane modules used for turbidity removal of river water, groundwater, drainage, etc., supply a reliable and stable amount of filtrate over a long period of time, together with automatic physical cleaning and automatic chemical cleaning. It is requested.

There are two types of hollow fiber membrane modules: an internal pressure type filtration method that performs filtration from the inside to the outside of the hollow fiber and an external pressure type filtration method that performs filtration from the outside to the inside of the hollow fiber. In the former, filtration by the cross flow method can be easily performed and the membrane is not easily clogged, and it is effective for removing turbidity by back washing. On the other hand, in the latter, turbid components easily collect between the hollow fibers during filtration, but filtration can be performed by using air bubbling and back washing together.

In the former case, in the case of a hollow fiber membrane module, back washing is often used for automatic physical washing. For example, a thin chemical agent such as sodium hypochlorite is mixed in the back cleaning solution to increase the back cleaning effect. Many proposals have been made for such driving methods. For example, Japanese Patent Laid-Open No. 06-227664 proposes an effective back cleaning method. Japanese Patent Laid-Open No. 06-238136 proposes that chlorine is mixed in the backwashing. In addition, JP 2001-170456 proposes performing effective back cleaning by stopping not only back cleaning.

These backwashing and the like require an effect of peeling off turbid components accumulated on the film surface from the film surface. In order to make this effective, it is necessary to have a structure inside the hollow fiber membrane module that can effectively drain the suspended turbid components out of the hollow fiber membrane module.

Japanese Patent Application Laid-Open No. 2000-246066 proposes a structure that can effectively discharge the concentrated liquid out of the hollow fiber membrane module. Japanese Patent Laid-Open No. 10-337449 proposes a structure in which the backwash liquid is uniformly dispersed inside the hollow fiber membrane bundle.
JP 2000-246066 A Japanese Patent Laid-Open No. 10-337449 WO03 / 59495 JP-A-6-226060

  However, if such a turbid component discharge structure is devised or the backwashing liquid is uniformly dispersed, the structure becomes complicated, the processing cost of the member becomes high, and the economy is reduced. In addition, since the structure is complicated, the hollow fiber storage area in the case is reduced, resulting in a reduction in compactness.

The present invention proposes a hollow fiber membrane module that can perform backwashing at low cost and prevent damage to the hollow fiber in an internal pressure type hollow fiber membrane module having a water collecting body.
The invention of claim 1 is composed of a cylindrical case, a plurality of hollow fiber membranes housed inside the case, and one or more water collecting bodies, between both ends of the hollow fiber membrane and between the hollow fiber membrane and the case. A hollow fiber membrane module that performs internal pressure filtration in which a gap is sealed with a resin and is filtered from the inside to the outside of the hollow fiber membrane, wherein at least a part of the water collecting body has a net-like portion. . A second aspect of the present invention is the hollow fiber membrane module according to the first aspect, wherein the water collecting body is a net-like cylinder. Further, according to claim 3, the net-like cylindrical body is arranged at the center of the case, and comprises two net-like cylindrical bodies on the side in contact with the hollow fiber membrane and the net-like cylindrical body on the side not in contact with the hollow fiber membrane, and The hollow fiber membrane module according to claim 2, wherein the hole diameter of the net-shaped cylinder on the side in contact with the hollow fiber membrane is smaller than the hole diameter of the net-shaped cylinder on the non-contact side. Further, in claim 4, the hole diameter of the net-shaped cylinder on the side in contact with the hollow fiber membrane is 5 to 200 μm, and the hole diameter of the net-shaped cylinder on the side not in contact with the hollow fiber film is 200 μm to 1 cm. Item 4. The hollow fiber membrane module according to Item 3.

The present invention relates to a hollow fiber membrane module that performs internal pressure type filtration that filters from the inside to the outside of a hollow fiber, and further includes a plurality of hollow fiber membranes and one or more water collecting bodies inside the case, and the hollow fiber membrane In the hollow fiber membrane module in which the ends between the ends and between the hollow fiber membrane and the case are sealed with a resin, the water collecting body can be effectively and inexpensively.

In the present invention, a net-like cylindrical body is used as a part or all of the water collecting body that guides permeate water out of the system or into which the cleaning liquid is introduced. It is preferable that the net can freely enter and exit the liquid and can be manufactured at low cost. Examples of the material include polyolefin resins such as PE and PP, nylon resins, PET, PMMA, polysulfone, AS, ABS, and fluorine-based resins. Also, a metal net made of stainless steel or copper may be used. The hole diameter of the net hole is not limited. For example, it may be 1 μm to 2 cm. From the viewpoint of liquid flow and prevention of damage to the hollow fiber, it is preferably 1 μm to 1 cm.

In the present invention, it is preferable to use a combination of two or more net-like cylinders. The net-like cylinder on the side that contacts the hollow fiber membrane (outside) has a small hole diameter so as not to damage the hollow fiber, while the net-like cylinder on the side that does not contact the hollow fiber membrane (inner side) has a large hole diameter. Do not block the flow of liquid. Further, it is preferable to keep the strength of the net by increasing the wire diameter of the wire constituting the net. The hole diameter of the outer net is preferably 5 to 200 μm, and the hole diameter of the inner net is preferably 200 μm to 1 cm. In order to further improve the effect, the hole diameter of the outer net is more preferably 5 to 100 μm, and the hole diameter of the inner net is more preferably 500 μm to 1 cm. The shape of the hole in the net is not limited, and examples thereof include a circle, a square, a trapezoid, and a rhombus. The wire diameter is usually preferably about 10% to 500% of the hole diameter. Furthermore, 30% to 300% is preferable because the balance between the prevention of damage to the hollow fiber and the passage of liquid is achieved.

The water collecting body of the present invention may have at least one net-like portion, but considering the dispersibility of the liquid flow, it is preferable that at least three or more net-like portions have a net shape. Furthermore, the whole may be configured in a net shape.

In the hollow fiber membrane module of the present invention, a hollow fiber membrane bundle is disposed around a water collection body. The hollow fiber membrane bundle may or may not be divided. If the water collecting body of the present invention is used, effective liquid can enter and exit, so that sufficient performance can be obtained without division. If splitting, split into several bundles. Any division method may be used. A corrugated partition may be used, or a hollow fiber bundle may be wound around a net and divided. As the dividing net, a net used in a general hollow fiber module can be used. Any number of divisions may be used. The greater the number, the better the dispersibility of the liquid, but the number of flow paths increases and the compactness is impaired. Preferably it is 2-16 divisions, More preferably, it is 4-8 divisions.

The material of the hollow fiber membrane used in the present invention is not particularly limited. For example, plastics such as polysulfone resin, nylon resin, polyethylene terephthalate resin, fluorine resin, polyacrylonitrile resin, PVA, polyolefin resin, and cellulose derivative resin may be used, or ceramic may be used. Metals or composite resins may be used. A cellulose derivative resin is preferable. This resin is highly hydrophilic. The contact angle is as small as 50 to 60 degrees, and dirt is less likely to adhere to the membrane by filtration compared to other resins. In addition, dirt once attached is easy to remove by physical cleaning such as reverse cleaning. Therefore, it is most suitable for the present invention. Further, the pore diameter of the membrane is not limited.

The hollow fiber membrane module of the present invention is a hollow fiber membrane module that performs internal pressure type filtration that filters from the inside to the outside of the hollow fiber, and has a plurality of hollow fiber membranes and one or more water collecting bodies inside the case. The ends of both ends of the hollow fiber membrane and between the hollow fiber membrane and the case are sealed with resin.

As for the shape of the case, there are no restrictions on the location and number of liquid outlets. For example, there may be two stock solution entrances and two filtrate entrances. They may be on the side of the case, only on one end or on both ends. The case referred to in the present invention may be divided or integrated. For example, the hollow fiber membrane bundle may be divided into a part that is directly housed inside and a cap part that covers both ends.

Also, any material may be used for the case. For example, plastics such as polysulfone resin, nylon resin, polyethylene terephthalate resin, fluorine resin, polyacrylonitrile resin, acrylic resin, polyolefin resin, polycarbonate, cellulose derivative resin, or ceramics may be used. Moreover, metals may be sufficient and the composite resin containing resin fiber, carbon fiber, glass fiber, etc. may be sufficient.

  In the present invention, any method may be adopted as a physical cleaning operation for removing fine particles adhering to the film. There are reverse cleaning, flushing, and air bubbling methods. A combination of these may also be used. Furthermore, you may combine the liquid containing chemical | medical solutions, such as sodium hypochlorite. It is preferable to perform physical cleaning by reverse cleaning without performing air bubbling. It is preferable that a chemical solution such as sodium hypochlorite is mixed in the back cleaning solution to increase the effect.

  In the hollow fiber membrane module of the present invention, an inexpensive and effective hollow fiber membrane module can be manufactured by devising the water collecting pipe.

  The method of the present invention can be carried out as follows. In FIG. 1, a hollow fiber bundle 1-3) and a cylindrical water collecting net 1-1) are accommodated in a cylindrical case 1-2) and both ends thereof are sealed with an adhesive 1-4). Both ends of the water collecting net 1-1) and the hollow fiber pass through the adhesive so that the liquid can enter and exit inside. Caps 1-5) are liquid-tightly connected to both ends of the cylindrical case via a sealing material (not shown) such as an O-ring. The cap has a liquid inlet / outlet (raw water nozzle 1-7)) supplied to the inside of the hollow fiber and a liquid outlet / outlet (permeation nozzle 1-6)) outside the hollow fiber through the water collecting net 1-1). It is. The connection tool 1-8) liquid-tightly connects the transmission nozzle 1-6) and the water collection net 1-1) via a sealing material (not shown) such as an O-ring. FIG. 2 shows a cross section of the central part of the module of FIG. The hollow fiber bundle is stored in the case almost uniformly without being divided. FIG. 3 shows a hollow fiber bundle divided into six. Each is wound around a net and stored in case 1-2).

FIG. 4 is a flowchart showing an operation method. A pipe is connected to the hollow fiber membrane module 4-1) of FIG. Raw water is supplied from the lower raw water nozzle of the hollow fiber membrane module by the raw water pump 4-5) from the raw water tank 4-2). The concentrate is discharged from the raw water nozzle and connected to the raw water line. The filtrate is discharged from the upper permeation nozzle and placed in the permeate tank 4-3). During the filtration, the filtration is stopped, and the membrane is washed by allowing the permeated water to flow backward by the reverse washing pump 4-6). You may supply a chemical | medical solution to a back washing | cleaning liquid via the chemical | medical solution pump 4-7) from the chemical | medical solution tank 4-4). By repeating this, an effective filtration operation is continued.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

  The hollow fiber membrane module shown in FIGS. 1 and 2 was produced. 6000 cellulose acetate hollow fiber membranes FUC1582 (inner diameter 0.8 mm, outer diameter 1.3 mm, manufactured by Daisen Membrane Systems) were stored in a PVC cylindrical case having an outer diameter of 165 mm, an inner diameter of 154 mm, and a total length of 1066 mm. There, a cylindrical net connected to a cylindrical pipe having an outer diameter of 60 mm and an inner diameter of 54 mm at both ends (Takiron Tri-Hishimenet NY53; net thickness 3 mm, hole diameter approximately 4.5 mm square was welded in a cylindrical shape. Tube) and a fine net (NB90 manufactured by NBC Kogyo Co., Ltd., NB90; 90 mesh) wound around it as a water collection net, put it in the center of the hollow fiber membrane bundle, and both ends together with the cylindrical case urethane adhesive (Coronate 4428 and Nipponporan 4221 were mixed; manufactured by Nippon Polyurethane Co., Ltd.) and sealed by centrifugal adhesion so as to have a thickness of 5 cm. After curing, the excess adhesive at both ends was cut to open the hollow fiber bundles at both ends and both ends of the water collecting net. A permeating nozzle and a raw water nozzle were connected in a liquid-tight manner to both ends of the case via a Victorian joint. At this time, liquid-tight sealing was performed using a connector having 0-rings at both ends between the transmission nozzle and the water collection net. The effective membrane area of the completed hollow fiber membrane module was 15 m2. This membrane module was connected to an apparatus similar to that shown in FIG. 4, and overrun was repeated to repeat filtration and backwashing. River water was used as raw water, filtration was performed for 30 minutes at a permeation flow rate of 3 m / D, and back washing was repeated for 2 minutes at a back washing flow rate of 6 m / D. Sodium hypochlorite was mixed in the reverse cleaning solution so that the free chlorine concentration was 3 ppm. This was continuously operated for one month.

The hollow fiber membrane module shown in FIGS. 1 and 3 was produced. Example 1 with the exception that the hollow fiber membrane bundle was divided into 6 pieces and a fine net (NB90; 90 mesh manufactured by NBC Kogyo Co., Ltd.) was used and the water collection net did not contain a fine net. A hollow fiber membrane module was prepared in exactly the same manner. Further, the filtration operation of the prepared hollow fiber membrane module was performed in exactly the same manner.
[Comparative Example 1]

A hollow fiber membrane was used in the same manner as in Example 2, except that a PVC cylindrical tube having an outer diameter of 60 mm, an inner diameter of 52 mm, and a length of 1066 mm was used instead of the water collection net, and 100 holes of 6 mm diameter were formed. Modules were created and evaluated for filtration.
[Comparative Example 2]

A hollow fiber membrane module was prepared in the same manner as in Example 1 except that the fine net outside the water collection net was removed, and filtration evaluation was performed.
[Filtration operation evaluation results]

  The following table shows the pure water permeation flux before and after filtration in Examples 1 and 2 and Comparative Examples 1 and 2 (the pure water permeation flux is the one converted to a transmembrane pressure of 98 kPa and a water temperature of 25 ° C.). . As a result, in both Examples 1 and 2, the rate of decrease before and after filtration was low. In Comparative Example 1, the rate of decrease was large. It can be presumed that the effect of back washing was low. In Comparative Example 2, it was confirmed that the hollow fiber was damaged by the water collection net. There was no leak due to damage.

  Sectional drawing of the hollow fiber membrane module of this invention.   Sectional drawing of the center part of the module of FIG. 1 (hollow fiber membrane module in which the hollow fiber membrane bundle is not divided).   Sectional drawing of the center part of the module of FIG. 1 (hollow fiber membrane module in which the hollow fiber membrane bundle is divided).   The flowchart which shows the filtration driving | operation method.

Explanation of symbols

1-1) Water collection net 1-2) Cylindrical case 1-3) Hollow fiber bundle 1-4) Adhesive 1-5) Cap 1-6) Permeating nozzle 1-7) Raw water nozzle 1-8) Connecting tool 2-1) Water collection net 2-2) Cylindrical case 2-3) Hollow fiber bundle 3-1) Water collection net 3-2) Cylindrical case 3-3) Hollow fiber bundle 4-1) Hollow fiber membrane module 4-2) Raw water tank 4-3) Permeated water tank 4-4) Chemical liquid tank 4-5) Raw water pump 4-6) Backwash pump 4-7) Chemical liquid pump

Claims (4)

  It consists of a cylindrical case, a large number of hollow fiber membranes housed inside the case, and one or more water collectors. The ends of the hollow fiber membranes and the hollow fiber membranes and the case are sealed with resin. A hollow fiber membrane module that performs internal pressure filtration that filters from the inside to the outside of the hollow fiber membrane, wherein at least a part of the water collector has a net-like portion.   The hollow fiber membrane module according to claim 1, wherein the water collecting body is a net-like cylinder.   The net-shaped cylinder is arranged at the center of the case, and includes a net-shaped cylinder on the side in contact with the hollow fiber membrane and a net-shaped cylinder on the side not in contact with the hollow fiber membrane, and the side in contact with the hollow fiber membrane The hollow fiber membrane module according to claim 2, wherein the hole diameter of the net-like cylinder is smaller than the hole diameter of the net-like cylinder on the side not in contact with the hollow fiber membrane.   4. The hole diameter of the net-shaped cylinder on the side in contact with the hollow fiber membrane is 5 to 200 [mu] m, and the hole diameter of the net-shaped cylinder on the side not in contact with the hollow fiber membrane is 200 [mu] m to 1 cm. Hollow fiber membrane module.

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