JP2002001068A - Method and apparatus for membrane separation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a membrane separation method which uses an osmotic pressure solution easy of acquisition and disposal and a small-size apparatus, performs membrane separation efficiently at a low operation pressure, and can obtain a high concentration solution with energy saved, and an apparatus for the method. SOLUTION: When liquid 5 to be treated which was pre-treated by a pre- treatment apparatus 4 is supplied to the concentration chamber 1b of a membrane separation module 1 by a pressure pump P1 and membrane-separated through a semipermeable membrane 1a, a part of the liquid is supplied from an osmotic pressure solution passage L2 to a permeation chamber 1c, the difference in osmotic pressure is reduced, a high concentration solution is obtained with the pressure of the pump reduced, the filtrate is membrane-separated with a post-membrane separation module 3, and the concentrated solution is returned to a treatment liquid tank 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a membrane separation method and apparatus using a semipermeable membrane, and more particularly to a membrane separation method and apparatus suitable for highly concentrated liquid.

[0002]

2. Description of the Related Art A membrane separation method has been employed in which a solvent is moved through a semipermeable membrane to concentrate a liquid to be treated and obtain a permeate. When a solution and its solvent are separated by a semipermeable membrane, the solvent permeates to the solution side by osmotic pressure. For this reason, in order to concentrate the solution, it is necessary to pressurize the solution side to allow the solvent to permeate against the osmotic pressure. Such a membrane separation method is called reverse osmosis (RO), and the semipermeable membrane used for this is called a reverse osmosis membrane. Normally, reverse osmosis is used when concentrating salt in a solution, but since osmotic pressure also occurs in a solution in which solutes other than salt are dissolved, even when concentrating a general solution in which solutes other than salt are dissolved. Osmotic pressure occurs and concentration takes place on a similar principle.

In such concentration by membrane separation, the permeation of the solvent is performed against the osmotic pressure. Therefore, in the case of a liquid to be treated having a high osmotic pressure, it is necessary to increase the operating pressure. This means that when the liquid to be treated is highly concentrated, or when the liquid to be treated having a high concentration is further concentrated to a higher concentration, it is necessary to perform membrane separation at a high pressure. However, increasing the operating pressure requires the entire device to be pressure-resistant and large.
There is a problem in that the amount of energy for pressurization also increases, and the installation cost and operation cost of the device increase. In addition, since the pressure resistance of the membrane used is limited, a concentration limit occurs.

As a membrane separation method for improving such points and performing high concentration at a low operating pressure, there has been proposed a method in which an osmotic pressure liquid is caused to flow on a permeate side to perform membrane separation (Japanese Patent Laid-Open No. 4-21).
No. 5822). This method allows a liquid having an osmotic pressure, which is different from the liquid to be treated, to flow to the permeate side, thereby performing membrane separation at a slightly higher operating pressure than the difference in osmotic pressure and performing high concentration. . That is, when the osmotic liquid having a higher osmotic pressure than the liquid to be treated flows, the solvent permeates from the liquid to be treated without pressurizing the liquid to be treated, but even when the osmotic liquid lower than the liquid to be treated flows, By flowing the liquid to be treated at a pressure slightly higher than the difference between the two osmotic pressures, the solvent permeates from the liquid to be treated and the membrane is separated. Therefore, it is possible to use a small pump having a low discharge pressure and perform membrane separation without using a pressure-resistant container to perform high concentration.

However, in such a conventional method,
Large volumes of osmotic fluid, diluted by solvent, were produced, and their disposal was difficult. There is not much problem when using an osmotic fluid that is easy to obtain and dispose like seawater, but use of this fluid is limited by the location conditions. In addition, in order to use such a liquid as an osmotic pressure liquid, it is necessary to perform a pretreatment so as not to adversely affect the membrane separation device. There was a problem.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to efficiently perform membrane separation at a low operating pressure by using an osmotic fluid and a small device that are easily available and disposed of, and to realize a high energy concentration at a low energy level. An object of the present invention is to provide a membrane separation method and an apparatus capable of obtaining a concentrated solution.

[0007]

The present invention is the following membrane separation method and apparatus. (1) The liquid to be treated is supplied to the concentration chamber formed on one side of the semipermeable membrane, and the osmotic fluid containing the liquid to be treated is supplied to the permeation chamber formed on the other side, and the solvent permeates from the concentration chamber side. A membrane separation method, wherein the membrane is separated by passing the light through a chamber. (2) The method according to the above (1), wherein the liquid to be treated is supplied to both the concentration chamber and the permeation chamber. (3) The method according to the above (1) or (2), wherein the concentrated liquid obtained by the pre-membrane separation is supplied as a liquid to be treated and the membrane is separated. (4) The method according to any one of (1) to (3) above, wherein the permeated liquid obtained from the permeation chamber is subjected to post-membrane separation, and the concentrated liquid is mixed with the liquid to be treated and subjected to membrane separation. (5) Any one of the above (1) to (4), in which a plurality of membrane separation modules in which a concentration chamber and a permeation chamber are partitioned by a semi-permeable membrane are provided, and the concentrated solution of the preceding stage is supplied as the liquid to be treated and the osmotic pressure solution of the subsequent stage. The method described in Crab. (6) a concentration chamber formed on one side of the semipermeable membrane and a permeation chamber formed on the opposite side, a liquid passage for supplying the liquid to be concentrated to the concentration chamber, and an osmotic pressure containing the liquid to be treated in the permeation chamber. An osmotic pressure liquid path for supplying the liquid, a differential pressure forming means for increasing the pressure in the concentrating chamber higher than the pressure in the permeating chamber, a condensing liquid path for taking out the condensed liquid from the concentrating chamber, and a permeating liquid for taking out the permeated liquid from the permeating chamber And a membrane separation device. (7) The apparatus according to the above (6), further comprising a branch channel for dividing the liquid to be processed from the liquid path to be processed to the osmotic pressure liquid path. (8) The method according to the above (6) or (7), further comprising a membrane separator for concentrating the low-concentration liquid and supplying the concentrated liquid as a liquid to be treated. (9) The apparatus according to any one of the above (6) to (8), further comprising a post-membrane separation device for concentrating the permeate obtained from the permeation chamber and mixing the concentrate with the liquid to be treated. (10) A multi-stage membrane separation module in which a concentration chamber and a permeation chamber are partitioned by a semi-permeable membrane, and a supply flow for supplying a concentrate of the preceding membrane separation module as a liquid to be treated and an osmotic pressure liquid of the subsequent membrane separation module. The apparatus according to any one of the above (6) to (9), including a road.

In the present invention, the target liquid to be subjected to membrane separation is a solution having an osmotic pressure and a solution in which a solute is dissolved in a solvent. However, an insoluble substance may be dispersed. Solutes include inorganic or organic salts, acids, alkalis, alcohols, sugars, proteins, and other soluble substances.
Further, even a dispersible substance includes a substance whose osmotic pressure is exhibited by the presence of a solvotropic part. Examples of the solvent include substances capable of forming a solution having an osmotic pressure by dissolving or dispersing these solutes or dispersoids. Water is typically used as such a solvent, but may be an alcohol or other solution.

In the present invention, the semipermeable membrane used for membrane separation is a membrane that allows the solvent in the liquid to be treated to permeate and prevents the permeation of solutes. Such semipermeable membranes include all semipermeable membranes that allow solvent to permeate by osmotic pressure or reverse osmosis. A semipermeable membrane usually called a reverse osmosis (R0) membrane is used for separating inorganic salts and low molecular weight organic substances from water, and is included in the semipermeable membrane of the present invention. In addition, nanofiltration (N
F) Membrane, ultrafiltration (UF) membrane, microfiltration (MF) membrane, etc., are membranes that separate water-soluble high molecular weight substances such as sugars and proteins using osmotic pressure or reverse osmosis. Included in the semipermeable membrane of the invention.

There is no limitation on the material of the semipermeable membrane, and cellulose acetate, polyamide, polyvinyl alcohol, polyacrylonitrile, polysulfone, nitrocellulose,
Triacetyl cellulose, regenerated cellulose, polycarbonate, polyether sulfone, vinylidene difluoride,
All materials generally used for semipermeable membranes such as tetrafluoroethylene, ceramic, polyolefin, polyethylene, polypropylene, and polyimide can be used. Such a semipermeable membrane is preferably used as a module. As the shape of these semipermeable membranes, those using an arbitrary shape semipermeable membrane such as a flat membrane, spiral, tubular, or hollow fiber can be used.

In the membrane separation apparatus of the present invention, a concentration chamber is formed on one side of the above semipermeable membrane, a permeation chamber is formed on the other side, and a liquid passage to be treated and a concentrated liquid path are connected to the concentration chamber. The osmotic pressure passage and the permeate passage are connected to each other, and a pressure difference forming means for increasing the pressure in the concentration chamber to be higher than the pressure in the permeation chamber is provided. As the membrane separation device, it is preferable to install a plurality of modules in which a concentration chamber and a permeation chamber are formed on both sides of the semipermeable membrane. These modules preferably have a concentration chamber and a permeation chamber separated by a semipermeable membrane. As the pressure difference forming means, a means for supplying the liquid to be concentrated to the concentration chamber under pressure using a pressure means such as a pump to perform membrane separation and allowing the permeated liquid to flow out from the permeation chamber side is preferable. A suction means such as the above may be used to suction the permeation chamber side to allow the permeate to permeate, or to permeate the permeate by osmotic pressure.

The osmotic pressure liquid is a liquid containing the liquid to be treated, and may be the liquid to be treated itself, or a diluent or concentrated liquid thereof. In order to supply the osmotic liquid containing the liquid to be treated to the permeation chamber, it is preferable to divide a part of the liquid to be treated into the osmotic liquid path through the branch channel from the liquid path to be treated,
(Amount of the liquid to be supplied to the concentrating chamber) / (Amount of the liquid to be supplied to the permeation chamber) is about 1 / 0.1 to 1/10, preferably about 1 / 0.5 to 1/5 by volume ratio. is there. A liquid other than the liquid to be treated may be supplied to the permeation chamber, but may not be supplied.

It is preferable that the liquid to be treated does not contain the same substance or other impurities. For this reason, when the stock solution contains impurities, it is preferable to use a liquid from which impurities have been removed by the pretreatment device as the liquid to be treated. Precipitation equipment as pretreatment equipment,
It is possible to use a treatment apparatus suitable for impurities to be removed, such as a coagulation sedimentation apparatus, a filtration apparatus, a membrane separation apparatus having a large pore diameter, and a sterilization apparatus. The pretreatment device can be mainly intended to prevent contamination or clogging of the semipermeable membrane, but to increase the purity of the obtained concentrated solution or permeate,
It can be performed for other purposes.

When the liquid to be treated is supplied and the membrane separation of the present invention is carried out, the difference in osmotic pressure between the concentration chamber and the permeation chamber is reduced. The solvent can be transmitted through the semipermeable membrane to the permeation chamber side. Therefore, using a small-sized, low-pressure apparatus, membrane separation can be efficiently performed with a small amount of energy, and a high-concentration liquid to be treated can be concentrated.

When the stock solution has a high concentration, for example, an osmotic pressure of 0.9
In the case of 8MP (10kgf / cm ² ) or more, the membrane separation according to the present invention can be performed using the undiluted solution as it is as the liquid to be treated. The membrane separation of the present invention can be carried out by supplying a concentrated liquid concentrated by ordinary membrane separation without supplying a liquid as a liquid to be treated. In this case, since the osmotic pressure liquid is not flowed in the pre-membrane separation, it is possible to effectively perform the concentration without discarding the pretreated stock solution.

[0016] When the membrane separation of the present invention is carried out as it is as the liquid to be treated due to the high concentration of the undiluted solution, or when the pretreatment liquid subjected to the pretreatment is used as the liquid to be treated, the liquid permeate obtained from the permeation chamber is not treated. Osmotic fluid containing the processing solution is mixed. For this reason, it is preferable to perform membrane separation using the same membrane separation device that does not flow the osmotic pressure liquid similar to that used for pre-membrane separation, and to mix the concentrated solution into the liquid to be treated to perform membrane separation. Thus, the liquid to be treated which has been subjected to the pretreatment can be effectively used. If the pretreatment and disposal are easy, the permeate may be discarded as it is.

In the present invention, a module in which a concentration chamber and a permeate chamber are divided by a semi-permeable membrane is provided in multiple stages, and the concentrate in the preceding stage is supplied to the concentration chamber and the permeate chamber as the liquid to be treated and the osmotic pressure solution in the next stage, respectively. When the flow path is formed as described above, and the pre-concentration is supplied as the liquid to be processed and the osmotic pressure liquid in the next step and membrane separation is performed, the concentration can be further increased to a higher concentration. By returning the permeate in each stage as the liquid to be treated in the preceding stage, efficient membrane separation can be performed. As in the case of general membrane separation, the concentrated solution may be supplied to the subsequent stage as it is, or may be circulated to the liquid tank to be treated to increase the degree of concentration and then sent to the subsequent stage.

[0018]

According to the present invention, the osmotic fluid containing the liquid to be treated is supplied to the permeation chamber and the membrane is separated, so that the osmotic fluid and the compact device which are easy to obtain and dispose can be used.
The membrane can be efficiently separated at a low operating pressure, and a concentrated solution having a low energy amount and a high concentration can be obtained. Further, when the liquid to be treated is supplied to both the concentration chamber and the permeation chamber, the configuration of the apparatus is simplified, and the processing is also facilitated. When the liquid to be treated is the concentrated liquid obtained by pre-membrane separation, the utilization rate of the pre-treated stock solution can be increased, and a low-concentration stock solution can be efficiently subjected to membrane separation. When the permeate is concentrated by post-membrane separation, and the concentrated liquid is mixed with the liquid to be treated and subjected to membrane separation, a high-concentration liquid to be treated can be directly subjected to membrane separation, and the utilization rate of the liquid to be treated is increased. Can be processed. Further, by installing modules in multiple stages and supplying the concentrated liquid as the liquid to be treated and the osmotic pressure liquid at the subsequent stage, high concentration can be achieved.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 are flowcharts showing different embodiments.

In FIG. 1, reference numeral 1 denotes a membrane separation module, in which a concentration chamber 1b is partitioned on one side and a permeation chamber 1c is partitioned on the other side by a semipermeable membrane 1a. 2 is a liquid tank to be treated,
The liquid passage L1 having the pressurizing pump P1 communicates with the concentration chamber 1b, and the osmotic pressure liquid passage L2, which diverges therefrom, communicates with the permeation chamber 1c via the valve V1. A permeate passage L3 having a pump P2 from the permeation chamber 1c communicates with the concentration chamber 3b of the post-membrane separation module 3. In the concentration chamber 1b, the concentrated liquid path L4
And in the case of the circulation type, the circulation path L5 is connected to the liquid tank 2 to be treated.
Contact The post-membrane separation module 3 is divided into a concentration chamber 3b and a permeation chamber 3c by a semi-permeable membrane 3a.
, The concentrated liquid path L6 communicates with the liquid tank 2 to be treated, and the permeation chamber 3c
And the permeate passage L7 communicates with the outside of the system. Reference numeral 4 denotes a pretreatment device, and a pretreatment undiluted solution path L9 for supplying a pretreatment undiluted solution obtained by pretreating the undiluted solution supplied from the undiluted solution path L8 communicates with the liquid tank 2 to be treated.

In the above membrane separation apparatus, the stock solution path L8
The pre-treatment device 4 pre-treats the stock solution supplied from the pre-treatment device 4 and sends the pre-treatment stock solution to the to-be-processed solution tank 2 from the pre-treatment stock solution passage L9. The liquid 5 to be treated in the liquid tank 2 to be treated is pressurized by the pressure pump P1 and supplied from the liquid passage L1 to the concentration chamber 1b of the membrane separation module 1 to perform membrane separation. At this time, a part of the liquid to be treated is used as the osmotic liquid and the flow rate is adjusted by the valve V1 while the osmotic liquid path L2
To the transmission chamber 1c. As a result, the difference between the osmotic pressures on both sides of the semipermeable membrane 1a is reduced, and even when the pressure of the pressurizing pump P1 is small, the solvent permeates through the semipermeable membrane 1a from the concentration chamber 1b and membrane separation is performed. The liquid is concentrated to a high concentration. The concentrate in the concentration chamber 1b is taken out of the concentrate path L4,
There are cases where the concentrated liquid is discharged out of the system as a transient method, and cases where the concentration is further increased by circulating the liquid from the circulation path L5 to the liquid tank 2 to be treated, and operation in either method is possible.

The permeated liquid in the permeation chamber 1c is taken out from the permeated liquid passage L3, pressurized by the pump P2, and sent to the concentration chamber 3b of the post-membrane separation module to perform post-membrane separation. The concentrated liquid in the concentration chamber 3b is a liquid to be treated that has entered the permeation chamber 1c as an osmotic pressure liquid,
The liquid component to be processed that has passed through the semipermeable membrane 1a is concentrated and supplied to the liquid tank 2 to be processed from the concentrated liquid path L6, and is used as the liquid to be processed. As a result, the utilization rate of the stock solution subjected to the pretreatment is increased. The permeated liquid in the permeation chamber 3c is taken out of the system as a processing liquid from the permeated liquid passage L7, and is used as recovered water or the like. The apparatus shown in FIG. 1 has a relatively high concentration of the stock solution, and is suitable for performing membrane separation as it is as the liquid to be treated in the present invention.

In FIG. 1, a nanofiltration membrane made of polyamide was used as a semipermeable membrane, and a 1% by weight aqueous solution of isopropanol was used as a stock solution, which was prepared at 0.98 MPa (10 kg / c).
(m ² , gauge pressure), when the membrane is separated by a circulation method using a pump operating pressure, the concentration of the concentrated liquid obtained from the concentrated liquid passage L4 becomes 2% by weight, and the concentration can be doubled. On the other hand, when the treatment is carried out under the same conditions without supplying the osmotic pressure liquid from the osmotic pressure liquid path, the concentration limit of the concentrated liquid is 1% by weight, and the concentration becomes impossible.

FIG. 2 shows an embodiment suitable for treating a stock solution having a relatively low concentration. The stock solution is configured to be concentrated by pre-membrane separation and used as a solution to be treated in the present invention. That is, reference numeral 6 denotes a pre-membrane separation module, which is divided into a concentration chamber 6b and a permeation chamber 6c by the semi-permeable membrane 6a.
Reference numeral 7 denotes a stock solution tank, and the liquid passage L11 to be concentrated has a pressure pump P3.
To the concentration chamber 6b. The permeated liquid passage L12 communicates with the permeation chamber 6c. From the concentration chamber 6b, a concentrated liquid path L13 is connected to the liquid tank 2 to be treated, and an osmotic pressure liquid path L2 branched therefrom communicates with the permeation chamber 1c of the membrane separation module 1. A permeate passage L3 is connected to the undiluted solution tank 7 from the permeation chamber 1c. Other configurations are the same as those in FIG.

In the membrane separation method using the above-described apparatus, the pretreatment stock solution pretreated in the pretreatment device 4 is used as the pretreatment stock solution path L9.
From the concentrated solution path L11, pressurized by the pressure pump P3, enters the concentration chamber 6b of the pre-membrane separation module 6, and performs pre-membrane separation. The solvent in the undiluted solution passes through the semipermeable membrane 6a and enters the permeation chamber 6c. Since the osmotic pressure liquid is not supplied to the permeation chamber 6c, the permeate is taken out of the permeate passage L12 as a processing liquid. The concentrated liquid in the concentration chamber 6b is supplied from the concentrated liquid path L13 to the liquid tank 2 to be treated as a liquid to be treated, and a part is supplied as the osmotic liquid from the osmotic liquid path L2 to the permeation chamber 1c of the membrane separation module 1. The membrane separation in the membrane module 1 is performed in the same manner as in FIG. 1, and the permeate is supplied to the stock solution tank 7 from the permeate passage L3. As a result, the permeate diluted with the undiluted solution introduced into the permeation chamber 1c as the osmotic pressure liquid is subjected to membrane separation by the pre-membrane separation module to concentrate the solute,
The utilization rate of the pretreatment stock solution can be increased.

In FIG. 2, a 0.1% by weight aqueous solution of isopropanol was used as a stock solution using a reverse osmosis membrane made of cellulose acetate as a semipermeable membrane.
/ Cm ² , gauge pressure), when the membrane is separated in a circulating manner with a pump operation pressure of 2%, the concentration of the concentrate obtained from the concentrate path L4 becomes 2
% By weight, and can be concentrated 20 times. On the other hand, when the treatment is performed under the same conditions without supplying the osmotic fluid from the osmotic fluid channel, the concentration of the concentrated solution is 1% by weight, and the concentration is 10 times.

FIG. 3 shows an embodiment in which the apparatus of FIG. 1 is configured in multiple stages. Reference numeral 11 denotes a second membrane separation module, which separates a concentration chamber 11b and a permeation chamber 11c by a semipermeable membrane 11a. Reference numeral 12 denotes a second liquid tank to be treated,
To be treated L21 having the second membrane separation module 1
One of the concentrating chambers 11b is communicated. Membrane separation module 1
The concentrated liquid path L4 communicates with the second liquid tank 12 to be treated, and the osmotic pressure liquid path L22, which is diverted therefrom, is connected to the second membrane separation module 1
This is in communication with the first permeated liquid chamber 11c. A permeated liquid passage L23 is connected to the liquid tank 2 to be processed from the permeation chamber 11c. A concentrated liquid passage L24 communicates with the concentrated liquid chamber 11b, and in the case of a circulation type, a circulation passage L25 communicates with the second treated liquid tank 12.

The membrane separation method using the above-described apparatus is performed in the same manner as in FIG. 1, but the concentration can be further increased by performing the membrane separation in multiple stages. That is, the concentrated liquid of the membrane separation module 1 is taken out from the concentrated liquid passage L4, a part of the concentrated liquid is introduced into the second treated liquid tank 12 as a liquid to be treated, and a part of the concentrated liquid is supplied as an osmotic liquid from the osmotic liquid passage L22 to the second liquid tank L22. It is sent to the permeation chamber 11c of the membrane separation module 11. Second treated liquid tank 1
The liquid to be treated 15 is pressurized by the pressurizing pump P4 and is supplied from the liquid to be treated L21 to the concentration chamber 1 of the second membrane separation module 11.
1b to perform membrane separation. Here, membrane separation is performed as in the case of the membrane separation module 1, and the liquid to be treated is concentrated. The concentrated liquid is taken out from the concentrated liquid passage L24 and discharged as it is in the case of a single-pass type, and is sent to the subsequent stage in the case of performing multi-stage membrane separation. In the case of the circulation type, the liquid is circulated from the circulation path L25 to the second processing liquid tank 12. The permeated liquid is the permeated liquid path L2
3 to the liquid tank 2 to be treated.

In FIG. 3, a nanofiltration membrane made of polyamide was used as a semipermeable membrane, and a 0.1% by weight aqueous solution of sucrose was used as a stock solution, which was pumped at a pump operating pressure of 0.98 MPa (10 kg / cm ² , gauge pressure). When the membrane is separated by a circulation method in the above, the concentration of the concentrated liquid obtained from the concentrated liquid path L24 becomes 3% by weight, and the concentration can be made 30 times. On the other hand, when the treatment is performed under the same conditions without supplying the osmotic fluid from the osmotic fluid channel, the concentration of the concentrated solution is 1% by weight, and the concentration is 10 times.

FIG. 4 shows an embodiment in which the apparatus of FIG. 2 is configured in multiple stages. The basic configuration is the same as that of FIG. 2, but the configurations of the second membrane separation module 11 and the second liquid tank 12 are the same as those of FIG. 3. I have. The membrane separation in the above-described apparatus is basically performed in the same manner as in FIG. 2, but the membrane separation in the second membrane separation module 11 is performed in the same manner as in FIG.

In FIG. 4, a reverse osmosis membrane made of polyamide is used as a semipermeable membrane, and a 0.2 wt% saline solution is used as a stock solution, which is pumped at a pump operating pressure of 1.47 MPa (15 kg / cm ² , gauge pressure). When the membrane is separated by a circulation method, the concentration of the concentrate obtained from the concentrate path L24 becomes 3% by weight,
15-fold concentration becomes possible. On the other hand, when the treatment is performed under the same conditions without supplying the osmotic fluid from the osmotic fluid channel, the concentration of the concentrated solution is 1% by weight, and the concentration is 5 times.

In the apparatus shown in FIGS. 3 and 4, when the number of membrane separation modules is further increased and the treatment is performed in multiple stages, the pressure can be further reduced and the concentration can be increased to a high concentration. In each of the above embodiments, the configurations of the membrane separation module and the flow path can be arbitrarily changed. Further, although the pressure pump is used as the differential pressure forming means, a suction pump may be used, and in some cases, an osmotic pressure may be used.

[Brief description of the drawings]

FIG. 1 is a flowchart of a membrane separation device according to an embodiment.

FIG. 2 is a flowchart of a membrane separation device according to another embodiment.

FIG. 3 is a flowchart of a membrane separation device according to still another embodiment.

FIG. 4 is a flowchart of a membrane separation apparatus according to still another embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 membrane separation module 2 liquid tank to be treated 3 post-membrane separation module 4 pretreatment device 5, 15 liquid to be treated 6 pre-membrane separation module 7 raw liquid tank 11 second membrane separation module 12 second liquid tank to be treated

Continued on the front page F-term (reference) 4D006 GA02 GA14 HA01 HA21 HA41 HA61 KA02 KA16 KA53 KA54 KA55 KA56 KA63 KA66 KB13 KB14 KB30 KE07Q MA01 MA02 MA03 MA04 MC12 MC18 MC23 MC29 MC30 MC33 MC39 MC45 MC49 MC54X MC32 PA25 PB12B52B

Claims (10)

[Claims] 1. A liquid to be treated is supplied to a concentration chamber formed on one side of a semipermeable membrane, an osmotic pressure liquid containing the liquid to be treated is supplied to a permeation chamber formed on the opposite side, and a solvent is supplied from the concentration chamber side. Membrane separation method, wherein the membrane is permeated into the permeation chamber to perform membrane separation. 2. The method according to claim 1, wherein the liquid to be treated is supplied to both the concentration chamber and the permeation chamber. 3. The method according to claim 1, wherein the concentrated liquid obtained by the pre-membrane separation is supplied as a liquid to be treated and the membrane is separated. 4. The method according to claim 1, wherein the permeated liquid obtained from the permeation chamber is subjected to post-membrane separation, and the concentrated liquid is mixed with the liquid to be treated and subjected to membrane separation. 5. The method according to claim 1, wherein a plurality of membrane separation modules are provided in which the concentration chamber and the permeation chamber are divided by a semipermeable membrane, and the concentrated liquid in the former stage is supplied as the liquid to be treated and the osmotic pressure liquid in the latter stage. The method described in. 6. A concentrating chamber formed on one side of the semipermeable membrane and a permeating chamber formed on the other side, a liquid passage for supplying a liquid to be processed to the concentrating chamber, and a permeating chamber containing the liquid to be processed. An osmotic fluid path for supplying the osmotic fluid, a differential pressure forming means for increasing the pressure in the concentrating chamber to a pressure higher than the pressure in the permeating chamber, a condensing liquid path for taking out the concentrated liquid from the concentrating chamber, and taking out the permeated liquid from the permeating chamber A membrane separation device including a permeate passage. 7. The apparatus according to claim 6, further comprising a branch channel for dividing the liquid to be processed from the liquid to be processed to the osmotic pressure liquid path. 8. The method according to claim 6, further comprising a pre-membrane separation device for concentrating the low-concentration liquid and supplying the concentrated liquid as a liquid to be treated. 9. The apparatus according to claim 6, further comprising a post-membrane separation device for concentrating the permeate obtained from the permeation chamber and mixing the concentrate with the liquid to be treated. 10. A multistage membrane separation module in which a concentration chamber and a permeation chamber are divided by a semipermeable membrane, and a concentrated solution of a preceding membrane separation module is supplied as a liquid to be treated and an osmotic pressure solution of a subsequent membrane separation module. Apparatus according to any of claims 6 to 9, including a supply channel.