JPH10137552A - Hollow-fiber membrane filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hollow-fiber membrane filter that can efficiently be backwashed with an improved backwashing action to restore its liq. permeability when the suspended matter contained in a liq. is filtered off by a hollow-fiber module, and the membrane surface of the hollow fiber is clogged. SOLUTION: The inside of a tank is divided by a horizontal partition plate 11 into a lower filtration chamber 1 and an upper filtrate chamber 2, plural hollow-fiber modules fixed respectively by a lower bundling plate 5 and a lower bundling plate 5 and with one end opened to the filtrate chamber are vertically supported in the filtration chamber, a skirt 7 is provided to the lowermost end of each module, an air inlet passage 9 is furnished in the lower bundling plate 5 to send air to the membrane surface of the hollow fiber from the skirt through the lower bundling part 5, each of the modules is a hollow-fiber not having a protective cylinder, the hollow fiber is opened at the upper and lower parts, and there are two types, i.e., a type with a sealed liq. collecting part provided to the lower opening and a type with the lower end closed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow fiber membrane filtration device for filtering fine suspended substances contained in a liquid, and a liquid to be treated is provided outside a hollow fiber membrane of the hollow fiber membrane filtration device. When the hollow fiber membrane is clogged by the suspended substance, water and air are passed through the hollow fiber membrane to filter the fine suspended matter contained in the liquid. The present invention relates to a hollow fiber membrane filtration device capable of recovering its function by washing with a filter.

[0002]

2. Description of the Related Art An example of a conventional technique relating to a hollow fiber membrane filtration device is a radioactive waste liquid treatment device in a nuclear power plant. FIG. 7 shows a flow of a radioactive waste liquid treatment apparatus using a hollow fiber membrane filtration device. The internal diameter of the external pressure type hollow fiber membrane filtration device 21 illustrated in FIG.
mm, the flow rate of radioactive waste liquid containing suspended substances in the apparatus is 10 to 40 m ³ / h, and the number of hollow fiber modules 24 installed in the filtration chamber 25 is 15 to 60. In addition,
In the figure, only one hollow fiber module 24 is shown.
The operation method of the radioactive waste liquid treatment apparatus will be briefly described below. Usually, a radioactive waste liquid containing a suspended substance having a concentration of about 1 to 20 ppm is supplied from the supply tank 22 to the supply pump 2.
By 3, water is passed through the external pressure type hollow fiber membrane filtration device 21. The value obtained by dividing the flow rate (m ³ / h) by the total membrane surface area (m ² ) of the hollow fiber module 24, that is, the LV value is approximately 0.07 to
A value of 0.15 m / h is chosen.

The hollow fiber used for the hollow fiber module 24 is made of various materials such as polyethylene, polyacrylonitrile, polysulfone, polyethersulfone, and cellulose triacetate. A value of about 0.1 μm is selected as the pore diameter of the hollow fiber membrane. As the water flows, the membrane surface of the hollow fiber of the hollow fiber module 24 becomes clogged, and the differential pressure increases. When the differential pressure rise reaches a certain value (usually a rise of 0.2 to 0.5 kg / cm ² with respect to the base differential pressure), the waste liquid treatment is stopped and a backwashing step is started.

[0004] Backwashing consists of air scrubbing and air bumps. Removal of suspended substances adhering to the hollow fiber membrane surface by the air scrubbing method usually involves removing air from the hollow fiber module 2.
4 from the lower side to the upper side, the yarn bundle is swung in the process of ascending the air bubbles, and the suspended substance mainly adhered between the yarns is peeled off. Next, air bumping is performed by pressing air from the filtrate chamber 26 into the hollow fiber. The pressurized air pressure is about 4 to 5 kg / cm ² G. By rapidly opening the backwash valve, the water in the filtrate chamber is released from the inside of the hollow fiber to the outside at a stretch by the force of air, and the suspended material that has firmly adhered to the hollow fiber membrane surface and the suspension that has penetrated the pores of the membrane Remove material. Either air scrubbing or air bump may precede. Usually, the combination of air scrubbing and air bump is performed twice. This is to improve the effect of the suspended solids by backwashing. After the backwash,
Move to water flow again.

The hollow fiber module used in the above-mentioned external pressure type hollow fiber membrane filtration device or the like has a partition plate partitioned into a filtration chamber and a filtrate chamber of the filtration device, one end of which is opened on the filtrate chamber side. Then, the plurality of hollow fiber modules are fixed so as to be supported in the filtration chamber. The liquid to be treated containing a suspended substance or the like is pressurized in the filtration chamber, is pressed into the membrane surface of the hollow fiber loaded in the hollow fiber module from the outside to the inside, and is filtered. In the hollow fiber module, the hollow fibers are typically stretched between an upper convergence plate and a lower convergence plate provided to fix them at both upper and lower ends. An example in which a hollow fiber is stretched between the upper and lower focusing plates is as follows.
As described in JP-A No. 5926, there is an example in which the upper end of the hollow fiber is fixed to the filtrate collecting chamber side and the lower end is fixed to the sealed liquid collecting chamber in the upper collecting plate. As another example, as described in the specification of Japanese Patent Application No. 59-270999, the upper end is opened to the filtrate chamber side, while the lower end is sealed and fixed. Any of the above types of hollow fiber modules is used depending on conditions such as the amount of the liquid to be treated and the concentration of the suspended substance contained in the liquid to be treated.

Referring to FIG. 8, a method of filtration and backwashing with a hollow fiber module described in the specification of Japanese Patent Publication No. 64-5926 will be described. 8, one end of a plurality of hollow fibers 30 penetrates and is fixed to the upper collecting plate 31. At the same time, the upper end of the protective outer cylinder 33 is fixed to the upper collecting plate 31. The upper collecting plate 31 is connected to the partition plate 34. Attach, and support the plurality of hollow fibers 30 in the filtration chamber 38 such that one end thereof opens to the filtrate chamber 37. In the center of the upper converging plate 31, a communication pipe (which becomes a support when no liquid passage is provided inside) 3
5 is attached, and a lower focusing plate 3
2 are provided. A hollow fiber 30 is stretched between the upper sizing plate 31 and the lower sizing plate 32, and a lower end of the hollow fiber 30 is fixed through the lower sizing plate 32 to form a hollow fiber module. The lower end of the cylinder 33 is also fixed to the lower focusing plate 32. The lowermost end of the hollow fiber module has a lid 36, forms a sealed liquid collecting chamber 39 together with the lower collecting plate 32, and the lower end of the hollow fiber 30 fixed through the lower collecting plate 32 is closed. 39 is open. The closed liquid collecting chamber 39 is provided with a plurality of hollow fibers 3.
The upper filtrate chamber is communicated with a communication pipe 35 passing through the center of the bundle of zeros. In addition, as can be seen from the above description, the outer periphery of the hollow fiber module is covered with the protective outer cylinder 33 here.

[0007] The filtration of the liquid to be treated is performed outside the hollow fiber module.
That is, the liquid to be treated is pressurized in the filtration chamber 38 of the external pressure type hollow fiber membrane filtration device, and the pressurized liquid to be treated is pressed into the hollow fiber 30 from outside to inside to be filtered. As for the filtrate, the liquid passing through the upper half of the hollow fiber 30 is conveyed to the filtration chamber 38, while the liquid passing through the lower half of the hollow fiber 30 is conveyed to the sealed collecting chamber 39, and the communication pipe 35.
To the upper filtrate chamber 37. During the continuation of the filtration, the suspension in the liquid to be treated is trapped on the outer surface of the hollow fiber 30 and the flow resistance of the hollow fiber 30 increases. I do. Backwashing is performed by injecting pressurized water into the hollow fiber 30 in a manner opposite to the time of filtration. That is, when pressurized water for backwashing is pressed into the filtrate chamber 37, the pressurized water flows from the filtrate chamber side (upper end of the hollow fiber 30) of each hollow fiber 30, through one communication pipe 35 and the sealed liquid collecting chamber 39, Water is pressed into the hollow fiber 30 from the lower end of the hollow fiber 30 and the suspension adhered to the outer membrane surface of the hollow fiber 30 is easily peeled off. This step may be performed using pressurized air instead of pressurized water. This case is called an air bump process.
This step is also performed in the backwashing step of a filtration device using a hollow fiber module described in the specification of Japanese Patent Application No. 59-270999 described later.

After that, air is sent to the hollow fiber module through a diffuser plate provided below the hollow fiber module,
An air scrubbing operation is performed in which air is sent to the bundle of hollow fibers through the protective outer cylinder 33 to remove suspended matter adhering to the membrane surface of the hollow fibers. In the case of the hollow fiber module described in JP-B-64-5926 shown in FIG. 8, the efficiency of removing suspended matter adhering to the hollow fiber membrane surface by air scrubbing operation is further improved. Is desired.

Next, referring to FIG.
The method of filtration and backwashing by the hollow fiber module described in the specification of No. 99 will be described. An upper convergence plate 41 is attached via an O-ring 46 to an opening of a partition plate 40 which is divided into a filtration chamber and a filtrate chamber of the filtration device. At the center of the upper focusing plate 41, a column 42 is attached.
A lower converging plate 43 is supported at the lower end of. A hollow fiber 44 is stretched between the upper focusing plate 41 and the lower focusing plate 43. The liquid to be treated is pressed into the hollow fiber 44 from outside to inside and filtered. In the case of this hollow fiber module, the end of the hollow fiber 44 on the lower convergence plate 43 side is closed by means such as an adhesive.

FIG. 10 is a view taken along the line EE in FIG. FIG.
At 0, a cutout portion 45 is provided in the lower focusing plate 43. This is because the liquid to be treated supplied from below can easily flow into the hollow fiber module, and at the same time, the flow path of the liquid to be treated to the bundle of the hollow fibers 44 can be secured, so that the filtration efficiency is improved. This is to make it easy for impurities to drop. The backwashing effect can be enhanced by using a hollow pipe for the support column 42 and forming a lateral hole in the side surface of the pipe. Japanese Patent Application No. 59-2709
In the hollow fiber module described in the specification of No. 99, a structure in which the hollow fiber 44 is stretched between the upper and lower convergence plates 41 and 43 and the outer rim of the hollow fiber module is used. No protective shell is used.
However, even in this type of hollow fiber module, the supply of scrubbing air to the inside of the bundle of hollow fibers is not sufficient, and further improvement is desired.

[0011]

When the suspended substance concentration is high or the filtration specific resistance is large and the differential pressure rises sharply, the backwashing effect is not always sufficient when the conventional technique is used. Is hard to say. There is a method in which the combination of air scrubbing and air bump is performed three times or more at the time of backwashing. However, in this case, the amount of waste of backwash waste increases. An object of the present invention is to improve the structure of a hollow fiber membrane filtration device to further improve backwashing.

[0012]

SUMMARY OF THE INVENTION An object of the present invention to improve the structure of a hollow fiber membrane filtration device and to provide a filtration device having an excellent backwashing effect is to provide an external pressure type hollow fiber membrane filtration device as follows. The problem is solved by loading the hollow fiber module of the present invention as shown. (1) The inside of the tank is divided into a lower filtration chamber and an upper filtrate chamber by a horizontal partition plate, each of which is fixed by the lower convergence plate and the lower convergence plate, and one end of which is opened in the filtrate chamber. The hollow fiber module is vertically supported in the filtration chamber, and a sealed liquid collecting chamber is provided at the lower end of the hollow fiber module with the other end of the opening communicating with the lower end of the hollow fiber module. Through a communication pipe, a skirt is provided at the lowermost end,
The hollow, wherein the lower collecting plate has an air introduction passage for allowing air to reach the membrane surface of the hollow fiber from the inside of the skirt portion through the lower collecting plate, and has no protective outer cylinder surrounding the hollow fiber module. Thread membrane filtration device.

(2) The inside of the tank is divided into a lower filtration chamber and an upper filtrate chamber by a horizontal partition plate, which are fixed by the lower collecting plate and the lower collecting plate, respectively, and one end of which is inserted into the filtrate chamber. A plurality of open hollow fiber modules are vertically supported in the filtration chamber, the other end of the hollow fiber module is closed, the lower collecting plate and the lower collecting plate are connected by a support, and a skirt portion is provided at the lowermost end. The lower focusing plate is provided with an air introduction path for air from inside the skirt portion to pass through the lower focusing plate to reach the membrane surface of the hollow fiber, and there is no protective outer cylinder surrounding the hollow fiber module. Hollow fiber membrane filtration device.

The external pressure type hollow fiber membrane filtration device described in the above (1) (hereinafter also referred to as “type 1 filtration device”) and the external pressure type hollow fiber membrane filtration device described in the above (2) (hereinafter referred to as the “type 1 filtration device”) 2), the tank is composed of a pressure-resistant vessel, and both the filtration chamber and the filtrate chamber can pressurize the liquid inside (and can pressurize separately).
A protective outer cylinder is not required for the filtration of the liquid to be treated or because the washing water can be easily pressurized during backwashing with pressurized water. Also, in the conventional hollow fiber module, the hollow fibers are usually entangled with each other during the air scrubbing operation (as a result of unnecessarily bundling many hollow fibers and / or unnecessarily loosely bundling hollow fiber membranes). Although a protective outer cylinder is provided in order to prevent this, in the hollow fiber module of the present invention, the hollow fiber is fixed at two upper and lower positions by an upper sizing plate and a lower sizing plate. It can be swung sufficiently during the scrubbing operation, and is fixed so that it has a moderate swelling in water.Therefore, there is no need to provide a protective outer cylinder because the hollow fiber membranes do not get entangled with each other without providing a protective outer cylinder. . This is one of the features of the present invention.

Another feature of the present invention is that a skirt portion having an air introduction path for swinging the hollow fiber is provided below the hollow fiber module. A detailed description is given in the description of the structure of the hollow fiber module and the filtration and backwashing operations. The protective outer cylinder surrounding the hollow fiber module in the type 1 and type 2 filtration devices of the present invention includes not only a hollow fiber module integrated with the hollow fiber module but also a case where it is directly provided on a partition plate in a tank. It is a thing. Further, in the hollow fiber module of the present invention, as described above, the protective outer cylinder is not provided for improving the air scrubbing property, etc., but when the hollow fiber module is attached to or detached from the external pressure type hollow fiber membrane filtration device. It is better to have a protective outer cylinder for workability, so the protective outer cylinder used at that time can be attached and detached with one touch, attach the protective outer cylinder at the time of loading, remove after loading, and when removing after use It is preferable if a protective outer cylinder can be attached.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The hollow fiber membrane filtration device of the type 1 will be described in more detail with reference to an example in which a hollow fiber module having the structure shown in FIG. Explain. The structure of the type 1 hollow fiber module and the backwashing operation of the present invention will be described below with reference to FIG. However, the hollow fiber membrane filtration device of the present invention is not limited by the following description. As shown in FIG. 1, a plurality of hollow fibers 3 are fixed to the upper bundle plate 4 so as to pass through the upper bundle plate 4, and the upper bundle plate 4 to which the bundle of hollow fibers is fixed is fixed. Is attached to the partition plate 11 together with the holding plate 12 with bolts 13. At this time, the upper end of the hollow fiber 3 is opened in the filtrate chamber 2, and the bundle of the hollow fibers 3 is in the filtration chamber 1. A communication tube 8 also serving as a support is attached to the center of the upper focusing plate 4, and a lower focusing plate 5 is supported at a lower end of the communicating tube 8, and between the upper focusing plate 4 and the lower focusing plate 5. A plurality of hollow fibers 3 are stretched.
The lower bundle plate 5 is fixed to the lower bundle plate 5 in a bundle shape such that the lower end of the hollow fiber 3 penetrates the lower bundle plate 5. The lower end of the hollow fiber 3 is open to the sealed liquid collecting chamber (water chamber) 6. A skirt portion 7 having a bottom plate 14 is fixed to the outer periphery of the lower collecting plate 5 to form a sealed liquid collecting chamber 6, and the skirt portion 7 penetrates the lower collecting plate 5 and the bottom plate 14 to allow air to pass through the hollow fiber. An air introduction passage 9 is provided inside the module.

The hollow fiber module assembled as described above is disposed in the filtration chamber 1 of the hollow fiber membrane filtration device, and the liquid to be treated containing suspended substances in the filtration chamber 1 is passed through the filtration chamber 1. When pressurized, the liquid to be treated is pressed into the membrane surface of the hollow fiber 3 from outside to inside and filtered. 2 and 3 show the hollow fiber module described in (1) of the present invention as viewed from the upper end (viewed from the arrow AA) and the lower end of the skirt portion 7 as viewed from the back (BB). Arrow view). During the continuation of filtration, the suspended matter in the liquid to be treated is trapped on the outer membrane surface of the hollow fiber 3 and the resistance of the hollow fiber 3 to flow increases. Perform washing. Contrary to the time of filtration, when the pressurized water for backwashing is pressed into the filtrate chamber 2 of the filtration device, one of the pressurized water is supplied to the hollow fiber 3 on the side of the filtrate chamber 7 of each hollow fiber 3.
The washing water is pressed into the hollow fiber 3 from the upper end of the hollow fiber 3 from the lower end of each hollow fiber 3 via the communication pipe 8 and the sealed liquid collecting chamber 6, and the suspension is attached to the outer surface of the hollow fiber 3. Helps to remove turbid matter. This step may be performed using pressurized air instead of pressurized water. This case is called an air bump process.

After backwashing using pressurized water or backwashing using air bumps, air is sent to the skirt portion 7 of the type 1 hollow fiber module of the type 1 hollow fiber module of the present invention via a diffuser plate at the bottom of the filtration chamber 1. . The air sent to the skirt portion 7 is introduced into the inside of the bundle of the hollow fibers 3 of the hollow fiber module through the air introduction passage 9 provided through the lower collecting plate 5 and the bottom plate 14, whereby the hollow fiber The bundle of 3 is shaken by the air from the inside, and by this disturbance, the adhered suspension that has been easily separated from the outer membrane surface of the hollow fiber 3 by the air bumps is separated. This step is the air scrubbing operation.

As described above, in the hollow fiber module in the type 1 filtration device of the present invention, the upper part of the bundle of hollow fibers 3 is open to the filtrate chamber, and the lower part of the bundle of hollow fibers 3 is the filtrate chamber. The bundle of hollow fibers 3 is stretched under a gentle tension between the filtrate chamber and the sealed liquid collection chamber, and the hollow fiber is provided at the lower part of the hollow fiber module. 3
Skirt portion 7 having an air introduction passage so that air for air scrubbing can be effectively and uniformly sent inside the bundle of
Is a feature of the present invention. Further, in the hollow fiber module of the present invention, since the protective outer cylinder is not provided, sufficient vibration can be given to the hollow fiber by scrubbing air without being restrained by the protective outer cylinder, and the air scrubbing property can be improved. Can be.

The hollow fiber membrane filtration device of the type 2 of the present invention will be described in more detail with an example in which a hollow fiber module having a structure shown in FIG. Can be. Hereinafter, the structure of the hollow fiber module and the backwashing operation in the type 2 filtration device of the present invention will be described with reference to FIG. However, the hollow fiber membrane filtration device of the present invention is not limited by the following description.

As shown in FIG. 4, a plurality of hollow fibers 3 of the hollow fiber module are fixed to an upper sizing plate 4, and the upper sizing plate 4 to which the bundle of the hollow fibers is fixed is separated from a partition plate. The structure attached to 11 is the same as the structure of the hollow fiber module in the type 1 filtration device. Also, type 2
Also in the hollow fiber module of the above, the support 16 is attached to the center of the upper collecting plate 4, and the lower collecting plate 5 is supported at the lower end of the support 16, and between the upper collecting plate 4 and the lower collecting plate 5. Although a plurality of hollow fibers 3 are stretched, in this case, the lower ends of the hollow fibers 3 fixed to the lower collecting plate 5 are closed, and the columns 16 need not be hollow. The reason is that in the hollow fiber module of this type, since the filtrate press-fitted into the hollow fiber is not discharged from the lower end of the hollow fiber 3, the upper filtrate chamber 2 passes through the communication pipe.
This is because there is no need to return the filtrate. Therefore, the skirt 7 provided at the lowermost end does not need to have a sealed liquid collecting chamber. However, the lower convergence plate 5
In order for the air for scrubbing to oscillate the hollow fiber membrane section through the through hole, a through hole is provided in the lower focusing plate 5 to form an air introduction passage 9.

The hollow fiber module assembled as described above is disposed in the filtration chamber 1 of the hollow fiber membrane filtration device, and the liquid to be treated containing the suspended substance in the filtration chamber 1 is passed through the filtration chamber 1. When pressurized, the liquid to be treated is pressed into the membrane surface of the hollow fiber 3 from outside to inside and filtered. FIGS. 5 and 6 show the hollow fiber module described in (2) of the present invention as viewed from the upper end (view taken along the line CC) and the lower end of the skirt portion 7 viewed from the back (DD). Arrow view).

In the backwashing of the hollow fiber module in the type 2 filtration device, pressurized water for backwashing is press-fitted into the filtrate chamber 2 of the filtration device. Water for washing is press-fitted into the hollow fiber 3 from the upper end of the hollow fiber 3, so that the suspension adhered to the outer membrane surface of the hollow fiber 3 is easily peeled off. This step may be performed by an air bump method. After backwashing with pressurized water or backwashing with air bumps, air is sent to the skirt portion 7 of the hollow fiber module via a diffuser plate at the bottom of the filtration chamber 1. The air sent to the skirt portion 7 oscillates the bundle of the hollow fiber membranes 3 of the hollow fiber module from the inside through an air introduction passage 9 provided through the lower collecting plate 5, and the hollow fibers are first air blown by air bumps. The adhered suspension which has been easily peeled off from the outer membrane surface of No. 3 is peeled off. This step is the air scrubbing operation.

In the hollow fiber module of this type 2 filtration device, the upper part of the bundle of hollow fibers 3 is opened to the filtrate chamber, and the bundle of hollow fibers 3 is stretched under gentle tension into the filtration chamber. The lower part of the hollow fiber 3 is sealed, and air is introduced into the lower part of the hollow fiber module so that air for air scrubbing can be sent effectively and uniformly inside the bundle of hollow fibers 3. It is a feature of the invention to provide a skirt 7 with a path. The method of stretching the bundle of the hollow fibers 3 into the filtration chamber under gentle tension may be performed, for example, by the above-described support method in which the bundle of the hollow fibers 3 is fixed by a support having a bundling plate on the upper and lower sides. . In addition, since the hollow fiber module does not include the protective outer cylinder, the hollow fiber can be sufficiently shaken without being restricted by the protective outer cylinder, and the air scrubbing property can be improved.

Further, in the hollow fiber module of any type of the filtration device of the present invention, the skirt portion 7
Even if there is scrubbing air flowing out of the skirt, it rises in the liquid as air bubbles, and the bundle of hollow fibers 3 is bulged out of the outer diameter of the skirt, which can contribute to the improvement of the air scrubbing property.

[0026]

The present invention will be described below in more detail with reference to examples. However, the present invention is not limited to only this embodiment.

(Example 1) Inside the external pressure type hollow fiber membrane filtration device in the radioactive waste liquid treatment device shown in FIG. 7, the hollow fiber module shown in FIG. 1 of the type 1 filtration device of the present invention was used. The liquid to be treated was filtered and backwashed. The internal diameter of the external pressure type waste filtration equipment used was 650 mm, and the flow rate of radioactive waste liquid containing suspended substances in the external pressure type filtration equipment was 15 m ^3.
/ H, 19 hollow fiber modules installed in the filtration chamber. The operation method of the radioactive waste liquid treatment apparatus will be briefly described below. A radioactive waste liquid containing a suspended substance having an average concentration of 17 ppm is passed from a liquid supply tank to an external pressure type hollow fiber membrane filtration device by a liquid supply pump. LV of passing water
A value of about 0.10 m / h was selected as the value.

The hollow fiber membrane used for the hollow fiber module is made of a polysulfone material, and the hollow fiber has a pore diameter of 0.1 mm.
1 μm was selected. When water is passed for 6 hours, the membrane surface of the hollow fiber of the hollow fiber module becomes clogged, and the differential pressure increases. Since the increase in the differential pressure reached 0.3 kg / cm ² , the backwashing step was started. In the backwashing, first, air scrubbing in which scrubbing air is supplied to the skirt portion of the hollow fiber module through an air diffuser in a filtration chamber of an external pressure type filtration device is performed.
Performed for 0 minutes, and then performed backwashing with an air bump for rapidly passing water from the filtrate chamber from the inside to the outside from the inside of the hollow fiber for about 10 seconds using 4 kg / cm ² of pressurized air as a driving force from the filtrate chamber,
Subsequently, when the air scrubbing was performed again for 20 minutes, the differential pressure of the hollow fiber module was not recognized.

(Comparative Example 1) In the filtration chamber of the external pressure type waste filtration equipment used in Example 1, the filter shown in FIG.
The hollow fiber module (described in US Pat. No. 270999) was loaded as in Example 1. The film area was the same for both. In the same manner as in Example 1, radioactive waste liquid was passed through the external pressure type waste filtration equipment from the supply tank at a value of about 0.10 m / h with an LV value of about 0.10 m / h. The hollow fiber used for the hollow fiber module was made of polysulfone and the hollow fiber had a pore diameter of 0.1 μm. When water is passed for 4.5 hours, the membrane surface of the hollow fiber of the hollow fiber module is clogged, and the differential pressure increases. The difference in water passage time between Example 1 and Comparative Example 1 is due to the difference in module structure. That is, Example 1 has a water collecting structure at both ends, the membrane surface of the hollow fiber can be used more effectively than the water collecting structure at one end of Comparative Example 1, and the rate of increase in the differential pressure is smaller. Since the increase in the differential pressure reached 0.3 kg / cm ² , the backwashing step was started. In the backwashing, first, air scrubbing for sending air for scrubbing to the bottom of the hollow fiber module through the air diffuser plate of the filtration chamber of the external pressure type filtration device for about 10 seconds is performed, and then 4 kg / cm ² is applied from the filtrate chamber. The hollow fiber module is finally obtained when air scrubbing and air bumping are performed three times by a method in which compressed air is supplied into the hollow fiber membrane to perform backwashing with air bumps, and then the air scrubbing is performed again for 20 minutes. Pressure difference was no longer observed.

[0030]

According to the present invention, the type 1 double-sided hollow fiber of the present invention is provided inside an external pressure type hollow fiber membrane filtration device used in a processing device such as the radioactive waste liquid processing device shown in FIG. A skirt portion is provided at the bottom of a hollow fiber module equipped with a membrane or a hollow fiber module equipped with a type 2 one-sided hollow fiber membrane to maximize the air for scrubbing sent through the diffuser plate in the filtration chamber. By efficiently feeding the inside of the hollow fiber bundle of the hollow fiber module and eliminating the conventional protective tube, the hollow fiber spreads like underwater flowers with the scrubbing air, and the scrubbing air is sufficiently hollow. The backwashing property can be improved by touching the yarn membrane. However, it is better to have a protective outer cylinder for the workability when installing and removing the hollow fiber module in the external pressure type hollow fiber membrane filtration device, so it is desirable to attach the protective outer cylinder detachably with one touch. . Needless to say, the feature of the present invention is that there is no protective outer cylinder during use.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of one example of a hollow fiber module of the present invention.

FIG. 2 is a view on arrow AA of the hollow fiber module of the present invention in FIG. 1;

FIG. 3 is a view of the hollow fiber module of the present invention shown in FIG.

FIG. 4 is a longitudinal sectional view of another example of the hollow fiber module of the present invention.

5 is a view of the hollow fiber module of the present invention shown in FIG.

6 is a view of the hollow fiber module of the present invention shown in FIG.

FIG. 7 is a diagram showing a flow of a radioactive waste liquid treatment apparatus used in the present invention.

FIG. 8 is a vertical cross-sectional view of an example of a conventional hollow fiber module including a double-sided hollow fiber.

FIG. 9 is a longitudinal sectional view of an example of a conventional hollow fiber module including a one-sided open type hollow fiber.

FIG. 10 is a view of the conventional hollow fiber module provided with the one-side open type hollow fiber of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Filtration room 2 Filtration room 3 Hollow fiber 4 Upper collecting plate 5 Lower collecting plate 6 Sealed collecting room 7 Skirt part 8 Communication pipe 9 Air introduction path 10 Communication pipe end part 11 Partition plate 12 Suppression plate 13 Bolt 14 Bottom plate 15 Packing DESCRIPTION OF SYMBOLS 16 Prop 21 External pressure type hollow fiber membrane filtration device 22 Supply tank 23 Supply pump 24 Hollow fiber module 25 Filtration chamber 26 Filtration chamber 30 Hollow fiber 31 Upper convergence plate 32 Lower convergence plate 34 Partition plate 35 Communication pipe 36 Cover 37 Filtrate chamber 38 Filtration chamber 39 Sealed liquid collecting chamber 40 Partition plate 41 Upper collecting plate 42 Support column 43 Lower collecting plate 44 Hollow fiber 45 Notch 46 O-ring

Claims (2)

[Claims] 1. The tank is partitioned into a lower filtration chamber and an upper filtrate chamber by a horizontal partition plate, fixed by a lower collecting plate and a lower collecting plate, respectively, and one end is opened in the filtrate chamber. A plurality of hollow fiber modules are vertically supported in the filtration chamber, and a lower end of the hollow fiber module is provided with a sealed liquid collection chamber having the other end of the opening communicated therewith. The lower chamber is provided with a skirt at the lowermost end thereof, and an air introduction passage for allowing air from inside the skirt to pass through the lower convergence plate to reach the membrane surface of the hollow fiber. Characterized in that there is no protective outer cylinder surrounding the hollow fiber module. 2. The tank is divided into a lower filtration chamber and an upper filtrate chamber by a horizontal partition plate, which is fixed by the lower collecting plate and the lower collecting plate, respectively, and one end of which is opened in the filtrate chamber. The plurality of hollow fiber modules are vertically supported in the filtration chamber, the other end of the hollow fiber module is closed, the lower convergence plate and the lower convergence plate are connected by a support, and a skirt portion is provided at the lowermost end. An air introduction passage for allowing the air from the inside of the skirt portion to pass through the lower focusing plate to reach the membrane surface of the hollow fiber is provided in the lower focusing plate, and there is no protective outer cylinder surrounding the hollow fiber module. Hollow fiber membrane filtration device.