JP3008945B1 - Combined filtration module and filtration method - Google Patents

Abstract

The present invention provides a filtration module capable of performing backwashing without interrupting filtration and continuously obtaining filtered water. A hollow fiber membrane containing chamber containing a first hollow fiber membrane and a second hollow fiber membrane, and a backwashing liquid supply port for supplying a backwash liquid to the hollow fiber membrane containing chamber during backwashing. And the first hollow fiber membrane is an internal pressure type fiber membrane 2 that filters the liquid to be filtered from the hollow part to the outside to obtain a one-step filtrate outside, and the second hollow fiber membrane has a second filtration water outlet 11. The composite filtration module, wherein the hollow fiber membrane is an external pressure type hollow fiber membrane 3 in which the one-stage filtrate is filtered from the outside to the hollow portion to obtain a two-stage filtrate in the hollow portion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite filtration module and a filtration method, and more particularly to a UF using a hollow fiber membrane.
("Ultrafiltration", the same applies hereinafter.) A module and a filtration method.

[0002]

2. Description of the Related Art Conventionally, as a filtration module using a hollow fiber membrane, for example, a module described in Japanese Utility Model Laid-Open No. 7-39923 or a module described in Japanese Utility Model Application Laid-Open No. 5-51433 is known. .

In Japanese Utility Model Laid-Open Publication No. 5-51433, a U-shaped porous hollow fiber membrane bundle A and a U-shaped porous hollow fiber membrane bundle B are arranged via a partition, and the open ends thereof are arranged. A two-stage filtration hollow fiber membrane module integrally fixed with resin and having a liquid collecting cap attached to an open end is described. According to the two-stage filtration hollow fiber membrane module, the fluid to be filtered is filtered from the outside of the hollow fiber of the hollow fiber membrane bundle A to the inner hole and collected in the liquid collecting cap. It is described that the solution is filtered to the outside through the inner hole of the hollow fiber of B and two-stage filtration is possible.

The filtration device described in Japanese Utility Model Laid-Open Publication No. 7-39923 is provided with a filtered water pressure regulating valve in a permeated liquid delivery path (filtered water outlet), and reverses the circulation direction of raw water to be filtered by a membrane filtration means. A four-way valve is provided to reduce the pressure outside the hollow fiber membrane (internal pressure type) to a pressure slightly lower than half of the pressure inside the hollow fiber membrane (inner pressure type = inlet pressure + outlet pressure). As a result, filtration is performed near the inlet of the hollow fiber membrane and backwashing is performed near the outlet, and backwashing is performed without interrupting the filtration. Backwashing of the entire hollow fiber membrane module is performed by reversing the circulation direction of the raw water by the four-way valve.

[0005]

Conventional backwashing of UF modules generally requires that the filtration be interrupted. Therefore, if it is desired to continuously obtain filtered water, a backup UF module is required, and the UF module must be switched during backwashing to perform filtration.

[0006] Japanese Utility Model Application Laid-Open No. 5-51433 does not disclose a method of backwashing the two-stage filtration hollow fiber membrane module. As in the conventional case, filtration must be interrupted at the time of backwashing. However, there is a problem that filtered water cannot be continuously obtained.

[0007] Further, the apparatus disclosed in Japanese Utility Model Laid-Open Publication No. 7-39923 can be backwashed without interrupting the filtration, but the pressure outside the hollow fiber membrane (internal pressure type) is changed to the pressure inside (the average circulating pressure =
(Inlet pressure + outlet pressure), it is necessary to adjust the pressure to slightly lower than half of the pressure and maintain the pressure. If the pressure cannot be maintained and the pressure cannot be maintained, filtration and backwashing can be performed simultaneously. could not. In addition, only a part of the hollow fiber membrane can be backwashed without interrupting the filtration. When the entire hollow fiber membrane is backwashed, the filtration needs to be interrupted.

[0008] An object of the present invention is to provide a filtration method capable of performing backwashing without interrupting filtration and continuously obtaining filtered water by means different from that described in Japanese Utility Model Application Laid-Open No. 7-39923. It is to provide a module and a filtration method.

[0009]

In order to achieve the above object, a composite filtration module according to the present invention comprises a hollow fiber membrane-containing chamber containing a first hollow fiber membrane and a second hollow fiber membrane, and a backwashing chamber. The first hollow fiber membrane has a backwashing liquid supply port for supplying a backwashing liquid to the hollow fiber membrane built-in chamber, and the first hollow fiber membrane filters the liquid to be filtered from the hollow portion to the outside, and supplies the one-stage filtrate to the outside. The second hollow fiber membrane is a hollow fiber membrane obtained by filtering the first-stage filtrate from the outside to a hollow portion to obtain a two-stage filtrate in the hollow portion.

[0010] The filtration method of the present invention is characterized in that the first-stage filtrate obtained by filtering the liquid to be filtered from the hollow portion of the first hollow fiber membrane housed in the hollow fiber membrane built-in chamber to the outside is removed. A filtration step of obtaining a two-stage filtrate by filtering from the outside of the second hollow fiber membrane contained in the fiber membrane containing chamber to the hollow part, and supplying a backwashing liquid to the hollow fiber membrane containing chamber and incorporating the hollow fiber membrane therein The backwash liquid is permeated from the outside of the first hollow fiber membrane contained in the chamber to the hollow portion to backwash the first hollow fiber membrane, and the reverse flow from the outside of the second hollow fiber membrane to the hollow portion is performed. It is characterized by having a back washing step of filtering the washing liquid to obtain a filtrate.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below. In the liquid to be filtered to be filtered by the filtration module of the present invention, the impurity particles to be removed by the filtration module of the present invention are dispersed in a dispersion medium. The filtration target liquid includes not only a liquid in which the dispersion medium is water, but also a liquid in which the dispersion medium is an organic solvent and a liquid in which the dispersion medium is a mixture of water and an organic solvent. The impurity particles contained in the liquid to be filtered are generally solid,
A liquid may be used as long as it can be filtered through a hollow fiber membrane.

The composite filtration module of the present invention is a filtration module using a hollow fiber membrane as described above, and has an internal pressure type and an external pressure inside a housing for accommodating the hollow fiber membrane, ie, a hollow fiber membrane built-in chamber. The two types of hollow fiber membranes are arranged, and at the time of normal filtration, for example, raw water, which is the liquid to be filtered, is passed through an internal pressure type hollow fiber membrane to be filtered to obtain one-stage filtered water. This is a UF module having a structure in which a two-stage filtered water, which is, for example, ultrafiltrated water, is also filtered again by a hollow fiber membrane.

On the other hand, when impurities such as aggregates are deposited on the inner surface of the internal pressure type hollow fiber membrane by ordinary filtration, the membrane must be washed (backwashed) in order to remove and wash the impurities. Backwashing water such as pure water is sent from the first-stage filtered water outlet to the hollow fiber membrane built-in chamber, and the internal pressure type hollow fiber membrane is washed with a reverse pressure to remove impurities and discharge. At the same time, in the external pressure type hollow fiber membrane, since the backwash water is filtered to obtain filtered water, the UF module is capable of continuous filtration without interrupting the filtration even during the backwash.

[0014] The hollow fiber membrane containing chamber contains a first hollow fiber membrane and a second hollow fiber membrane. The backwash liquid supply port is for supplying the backwash liquid to the hollow fiber membrane built-in chamber at the time of backwash, and one or more backwash liquid can be provided as necessary. The first hollow fiber membrane is
The liquid to be filtered is filtered from the hollow portion to the outside to obtain a one-stage filtrate outside, and one or more filters can be built in the hollow fiber membrane built-in chamber. The second hollow fiber membrane is for filtering the one-stage filtrate from the outside to the hollow part to obtain a two-stage filtrate in the hollow part, and can be incorporated in the hollow fiber membrane built-in chamber one or more times.
The backwash liquid supply port is connected to the hollow fiber membrane built-in chamber during filtration.
It can also serve as a one-stage filtrate outlet for discharging the stage filtrate. The backwash liquid may be any liquid that can backwash the hollow fiber membrane, and for example, pure water or the like can be used.

The embodiments of the present invention will be described in more detail with reference to specific examples.

[0016]

Embodiment [Structure of Embodiment] A single UF module has a structure in which thousands to hundreds of thousands of straw-shaped hollow fiber membranes having a diameter of about 1 mm are bundled depending on the size of the module. As the hollow fiber membrane, two types of hollow fiber membranes, an internal pressure type hollow fiber and an external pressure type hollow fiber, are arranged in the same UF module. Of these two types of hollow fibers, the internal pressure type hollow fiber supplies raw water for filtration to the inside, and the filtered water is obtained outside through the membrane, and the external pressure type hollow fiber is the raw water for filtration outside the membrane. And filtered water is obtained inside.

It is desirable that the two types of hollow fiber membranes are arranged in the UF module in the UF module, in which the internal pressure type and the external pressure type are arranged in a lattice, but it is difficult to form the module. 2, hollow fibers of the internal pressure type and the hollow fiber membranes of the external pressure type can be grouped every several tens and arranged in a lattice. That is, the bundle of the internal pressure type hollow fiber membranes and the bundle of the external pressure type hollow fiber membranes can be arranged in parallel or substantially parallel in the same direction at an interval.

The ratio of the number of the internal pressure type hollow fiber membranes to the number of the external pressure type hollow fiber membranes is generally defined as the ratio of the amount of filtered water at the time of filtration and backwashing.
It cannot be determined unequivocally because it differs depending on the capacity difference between the hollow fiber membranes of the internal pressure type and the external pressure type to be used, and also depends on the quality of the raw water to be filtered and the supply pressure. However, when the filtration capacity of the hollow fiber membrane is the same for the internal pressure and the external pressure type, the raw water supply pressure, the amount of water and the backwash water supply pressure, and the amount of water are the same, for example, the amount of filtered water during normal filtration and backwash When they are the same, the ratio can be basically set to the ratio of the number of internal pressure type hollow fiber membranes to the number of external pressure type hollow fiber membranes = 1: 1. Here, the amount of filtered water at the time of normal filtration is the total amount of the one-stage filtered water and the two-stage filtered water, and the amount of filtered water at the time of back washing is the amount of one-stage filtered water.

The configuration of the UF module of the embodiment will be described in more detail with reference to FIGS. FIG. 1 is a schematic cross-sectional view of a filtration module according to an embodiment of the present invention in a direction in which raw water, which is a liquid to be filtered, flows when the filtration module is normally filtered. FIG. 2 is a schematic cross-sectional view of the filtration module of the embodiment of the present invention in the direction in which the backwash water flows when the filtration module is backwashed and filtered. As described above, the internal pressure type hollow fiber membranes and the external pressure type hollow fiber membranes are each bundled in a plural number, but are simply shown as a single tube in FIGS.

Inside the substantially cylindrical filtration module 1, partitions 4a, 4c and 4b are provided in order from the upstream side, and a raw water dividing chamber A, a concentrated raw water merging chamber B, and a hollow fiber membrane built-in chamber C are provided. And the two-stage filtered water merging chamber D. The partition walls 4a, 4c and 4b are formed by curing an adhesive, respectively.

The internal pressure type hollow fiber membrane 2 is adhesively fixed to the partition walls 4a and 4b such that one open end communicates with the raw water inlet 9 and the other open end communicates with the concentrated raw water outlet 10. ing. The external pressure type hollow fiber membrane 3 has one opening end embedded in the partition wall 4b so as to prevent the liquid from flowing in and is air-tightly bonded and fixed, and the other opening end communicates with the junction chamber D of the two-stage filtered water. It is adhesively fixed to the partition 4c. The external pressure type hollow fiber membrane 3 may be provided by being adhered and fixed to the partition wall 4c such that both open ends communicate with the merged chamber D of the two-stage filtered water.

[Explanation of Operation of Embodiment] The filtering operation will be described with reference to FIGS. First, during normal filtration, raw water 5 is supplied from a raw water inlet 9. The raw water is diverted in the distribution chamber A of the raw water, flows in from one open end of the internal pressure type hollow fiber membrane 2, is filtered from the inner hollow portion of the internal pressure type hollow fiber membrane 2 to the outside, and is filtered. , That is, one-stage filtered water is obtained in the hollow fiber membrane built-in chamber C. The unfiltered raw water containing aggregates and the like flows out from the other open end of the internal pressure type hollow fiber membrane 2 and joins in the concentrated raw water merging chamber B to form the concentrated raw water outlet 1 as the concentrated raw water 8.
It is discharged from 0.

1 obtained by filtration through the internal pressure type hollow fiber membrane 2
The first-stage filtered water fills the hollow fiber membrane built-in chamber C and is discharged as the first-stage filtered water 6 from the first-stage filtered water outlet 11, and the first-stage filtered water that is not discharged is further subjected to the external pressure type hollow fiber membrane 3 by the external pressure type hollow fiber membrane 3. Filtration is performed again from the outside of the fiber membrane 3 to the inside hollow part, and two-stage filtered water is obtained in the inside hollow part of the external pressure type hollow fiber membrane 3.
The two-stage filtered water flows out from the open end of the external pressure type hollow fiber membrane 3, passes through the two-stage filtered water merging chamber D, and is discharged as the two-stage filtered water 7 from the two-stage filtered water outlet 12. 1-stage filtered water outlet 11
Can be closed by a valve or the like.
Only staged water 7 is obtained. In addition, this two-stage filtered water is:
It is usually obtained only during filtration, but not during backwashing.

Next, at the time of backwashing, the supply of the raw water 5 from the raw water inlet 9 is stopped, and the first-stage filtered water outlet 11 from which the first-stage filtered water has flowed out during filtration is used as a backwashing liquid supply port. Backwash water 13 such as pure water is supplied to the hollow fiber membrane built-in chamber C from the liquid supply port. A certain amount of the backwash water in the hollow fiber membrane built-in chamber C that has flowed in from the first-stage filtered water outlet 11 can be used to remove aggregates and the like adhering to the inside of the internal pressure type hollow fiber membrane 2 under reverse pressure. At the same time as washing (backwashing) and removal, the remaining backwash water is filtered from the outside to the inside hollow portion by the external pressure type hollow fiber membrane 3, and filtered water is obtained in the hollow portion inside the external pressure type hollow fiber membrane 3. Even when the internal pressure type hollow fiber membrane 2 is backwashed, the first-stage filtered water 14 is obtained from the two-stage filtered water outlet 12.

However, at the time of backwash filtration, only one-stage filtration by the external pressure type hollow fiber membrane 3 is performed, so that two-stage filtration cannot be performed. However, if the one-stage filtered water filtered by the internal pressure type hollow fiber membrane 2 is used as backwash water, substantially two-stage filtered water can be obtained.

The backwash drainage in the tube of the internal pressure type hollow fiber membrane 2, that is, the water that has washed the internal pressure type hollow fiber membrane 2, flows out of the two open ends at both ends of the internal pressure type hollow fiber membrane 2, and the open end. From the concentrated raw water outlet 10 and the raw water inlet 9 which are respectively communicated with the backwater.

With respect to washing (backwashing) of the external pressure type hollow fiber membrane 3, the water filtered by the internal pressure type hollow fiber membrane 2 during filtration is usually used.
Since backwashing water such as pure water is used at the time of backwashing the internal pressure type hollow fiber membrane 2, there is no need for the external pressure type hollow fiber membrane 3 since it is considered that there is no adhesion of aggregates and the like.

[0028]

As described above, according to the present invention,
The following effects can be obtained.

The first effect of the filtration module of the present invention is as follows.
This means that filtered water can be continuously obtained without interrupting filtration even during back washing for removing aggregates and the like attached to the hollow fiber membrane.

The reason is that the filtration module of the present invention
A hollow fiber membrane built-in chamber containing the first hollow fiber membrane and the second hollow fiber membrane, and a backwash liquid supply port for supplying a backwash liquid to the hollow fiber membrane built-in chamber during backwashing; The first hollow fiber membrane is a hollow fiber membrane that filters the liquid to be filtered from the hollow part to the outside to obtain a one-stage filtrate outside, and the second hollow fiber membrane transfers the one-stage filtrate from the outside to the hollow part. This is because the hollow fiber membrane was filtered to obtain a two-stage filtrate in the hollow part.

The second effect of the filtration module of the present invention is as follows.
A filter module for backup is not essential, and can be constituted by one module, so that it is suitable for a small one. The reason is the same as the reason for the first effect.

The effect of the filtration method of the present invention is that filtered water can be continuously obtained without interrupting filtration even during back washing for removing aggregates and the like attached to the hollow fiber membrane. is there.

The reason for this is that the filtration method of the present invention uses a one-stage filtrate obtained by filtering the liquid to be filtered from the hollow portion of the first hollow fiber membrane incorporated in the hollow fiber membrane built-in chamber to the outside. A filtration step of filtering from the outside of the second hollow fiber membrane contained in the hollow fiber membrane built-in chamber to the hollow portion to obtain a two-stage filtrate, and supplying a backwashing liquid to the hollow fiber membrane built-in chamber to form the hollow fiber The backwash liquid is permeated from the outside of the first hollow fiber membrane contained in the membrane containing chamber to the hollow portion to backwash the first hollow fiber membrane, and from the outside of the second hollow fiber membrane to the hollow portion. This is because a backwashing step of filtering the backwash solution to obtain a filtrate is provided.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an example of a filtration module of the present invention in a direction in which raw water flows.

FIG. 2 is a schematic cross-sectional view of an example of the filtration module of the present invention in a direction in which backwash water flows.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Filtration module 2 Internal pressure type hollow fiber membrane 3 External pressure type hollow fiber membrane 4a, 4b, 4c Partition wall 5 Raw water (supply water) 6 1st stage filtered water 7 2nd stage filtered water 8 Concentrated raw water 9 Raw water inlet 10 Concentrated raw water outlet 11 1 stage Filtration water outlet 12 Two-stage filtration water outlet 13 Backwash water 14 One-stage filtration water (backwash water) 15, 16 Backwash drainage A Raw water splitting room B Concentrated raw water merging room C Hollow fiber membrane built-in room D Two-stage filtration Water junction room

Claims (8)

(57) [Claims] 1. A hollow fiber membrane containing chamber containing a first hollow fiber membrane and a second hollow fiber membrane, and a backwash liquid supply port for supplying a backwash liquid to the hollow fiber membrane containing chamber during backwashing. The first hollow fiber membrane is a hollow fiber membrane that filters a liquid to be filtered from a hollow portion to the outside to obtain a one-stage filtrate to the outside,
The composite filtration module, wherein the hollow fiber membrane is a hollow fiber membrane that filters the first-stage filtrate from the outside to a hollow portion to obtain a two-stage filtrate in the hollow portion. 2. The composite according to claim 1, wherein the backwash liquid supply port also serves as a first-stage filtrate outlet for allowing the first-stage filtrate to flow out of the hollow fiber membrane built-in chamber during filtration. Type filtration module. 3. The first hollow fiber membrane according to claim 1, wherein one of the open ends communicates with the inlet of the liquid to be filtered and the other communicates with the outlet of the concentrated liquid of the liquid to be filtered. A composite filtration module according to any one of the preceding claims. 4. The composite filtration module according to claim 1, wherein at least one of the open ends of the second hollow fiber membrane communicates with a two-stage filtrate outlet. 5. A flow dividing chamber for allowing a liquid to be filtered to flow into the open ends of the plurality of first hollow fiber membranes, the upstream side of the plurality of first hollow fiber membranes, wherein the openings of the plurality of first hollow fiber membranes are provided. The combined filtration according to any one of claims 1 to 4, wherein a confluent chamber for the concentrated liquid that joins the concentrated liquid flowing out from an end is provided downstream of the plurality of first hollow fiber membranes. module. 6. A two-stage filtrate merging chamber for merging two-stage filtrates flowing out from the open ends of the plurality of second hollow fiber membranes is provided downstream of the plurality of second hollow fiber membranes. The combined filtration module according to claim 1. 7. A one-stage filtrate obtained by filtering a liquid to be filtered from the hollow portion of the first hollow fiber membrane housed in the hollow fiber membrane built-in chamber to the outside, is housed in the hollow fiber membrane built-in chamber. A filtration step of filtering from the outside of the second hollow fiber membrane to the hollow part to obtain a two-stage filtrate, supplying a backwashing liquid to the hollow fiber membrane built-in chamber and installing the second washing liquid in the hollow fiber membrane built-in chamber. (1) The backwash liquid is permeated from the outside of the hollow fiber membrane to the hollow part to backwash the first hollow fiber membrane, and the backwash liquid is filtered from the outside of the second hollow fiber membrane to the hollow part to filter. A filtration method comprising a backwashing step of obtaining a liquid. 8. A one-stage filtration step in which a liquid to be filtered is one-stage filtered from a hollow portion of the first hollow fiber membrane to the outside to obtain a one-stage filtrate, and the one-stage filtrate is subjected to the second hollow fiber membrane. The filtration method according to claim 7, further comprising a two-stage filtration step of performing two-stage filtration from the outside to a hollow portion to obtain a two-stage filtrate.