JPH11290849A - Apparatus and method for desalting salt water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a high recovery while preventing the lowering of membrane capacity caused by a silica scale. SOLUTION: Backwashing mechanisms 5 are provided to second and third stage reverse osmosis membrane modules 3b, 3c among a plurality of reverse osmosis membrane modules 3a, 3b, 3c and backwashing is periodically performed. Vibration generators are arranged to the second and third stage reverse osmosis membrane modules 3b, 3c among a plurality of the reverse osmosis membrane modules 3a, 3b, 3c and a specific vibration with vibration frequency of 5-100 Hz is applied to the vibration generator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a desalination apparatus and a desalination method for desalinating brackish water using reverse osmosis membrane modules connected in a plurality of stages.

[0002]

2. Description of the Related Art Conventionally, drinking water is obtained by desalinating brackish water such as river water, well water, tap water, and industrial water using a water treatment technique such as coagulation filtration. However, in recent years, harmful substances such as arsenic, fluorine, nitrogen, pesticides, and trihalomethane have been included in raw water, and drinking water that satisfies a predetermined tap water standard may not be obtained using only conventional water treatment technology. . Therefore, desalination of brackish water is sometimes performed by using reverse osmosis membrane modules connected in multiple stages in order to desalinate raw water and remove the above harmful substances.

FIG. 3 is a schematic diagram showing an example of a conventional brine desalination apparatus using a plurality of stages of reverse osmosis membrane modules.

In FIG. 3, raw water is supplied to a pretreatment device 1. In the pretreatment device 1, raw water is subjected to pretreatment such as coagulation sedimentation sand filtration, coagulation filtration, microfiltration, ultrafiltration, and the like. The water pretreated by the pretreatment device 1 is supplied to the raw water inlet of the first-stage reverse osmosis membrane module 3a by the high-pressure pump 2.
Alternatively, the water treated by the pretreatment device 1 may be temporarily stored in the tank 7A and then supplied to the raw water inlet of the first-stage reverse osmosis membrane module 3a by the high-pressure pump 2.

[0005] The concentrated water discharged from the concentrated water outlet of the first-stage reverse osmosis membrane module 3a is supplied to the raw water inlet of the second-stage reverse osmosis membrane module 3b. The concentrated water discharged from the concentrated water outlet of the second-stage reverse osmosis membrane module 3b is supplied to the raw water inlet of the third-stage reverse osmosis membrane module 3c.

The concentrated water discharged from the concentrated water outlet of the reverse osmosis membrane module 3c at the third stage is discharged out of the system through the concentrated water piping 31. In addition, the permeated water discharged from the permeated water outlets of the first, second, and third reverse osmosis membrane modules 3a, 3b, and 3c is a permeated water pipe 30 respectively.
a, 30b, and 30c are supplied to and stored in the tank 7B.

[0007]

The brine desalination apparatus using the above-described multiple-stage reverse osmosis membrane module can obtain a water recovery rate of 80% or more, preferably 90% or more, due to the processing cost and the like. It is not practical without it. However, when the water recovery rate is increased, the hardness component and silica are concentrated and precipitate as scale on the membrane surface of the reverse osmosis membrane, resulting in a decrease in membrane performance. Therefore, it has been difficult to increase the water recovery rate to 80% or more in the above-described brine desalination apparatus.

[0008] Therefore, when the water recovery rate is increased by reducing the hardness component or silica at the stage of pretreatment of the reverse osmosis membrane module or by injecting a chemical for preventing the formation of scale, the scale of water is increased. Methods have been proposed to prevent this from occurring.

FIG. 4 is a schematic diagram showing an example of a conventional brine desalination apparatus for preventing the generation of scale when the water recovery rate is increased.

In FIG. 4, water pretreated by a pretreatment device 1 is supplied to a scale component removal treatment device 8 for removing or preventing scale components. The scale component removal treatment device 8 reduces the precipitation of silica and hardness components by injecting, for example, a scale inhibitor or an acid into the supply water. The water treated by the scale component removal treatment device 8 is supplied to the raw water inlet of the first-stage reverse osmosis membrane module 3a by the high-pressure pump 2. After that,
This is the same as the processing in the brine desalination apparatus of FIG.

According to the brine desalination apparatus shown in FIG. 4, it is expected that the rate of water recovery is increased while the generation of scale is prevented.
However, since it is necessary to inject a large amount of a scale inhibitor and an acid in order to remove the scale component in the scale component removal processing device 8, there is a problem that the processing cost is increased. Therefore, there has been a demand for a practical brine desalination apparatus and a brine desalination method that are economical.

An object of the present invention is to provide a desalination apparatus and a desalination method which can realize a high water recovery rate while preventing a decrease in membrane performance due to scale at a low treatment cost.

[0013]

Means for Solving the Problems and Effects of the Invention A water desalination apparatus according to the first invention is a water desalination apparatus for performing desalination of water by a reverse osmosis membrane module connected in plural stages. Of these, at least one of the second and subsequent reverse osmosis membrane modules is provided with a backwash mechanism for performing backwash from the permeated water side. The amount of permeated water used for backwashing is desirably 10% or less of the total amount of permeated water.

In this brine desalination apparatus, at least one of the second and subsequent reverse osmosis membrane modules is periodically subjected to backwashing to prevent scale generated on the membrane surface from depositing on the membrane surface. can do. Thereby, a high water recovery rate can be realized while preventing deposition of scale at a low processing cost. Therefore, it is possible to economically desalinate brackish water without lowering the membrane performance due to the scale.

A second aspect of the invention provides a desalination apparatus for desalinating brine using a reverse osmosis membrane module connected in a plurality of stages. Of the reverse osmosis membrane module provided with a vibration generator.

In this brine desalination apparatus, by applying vibration to at least one of the second and subsequent reverse osmosis membrane modules, aggregation of scale components can be prevented and generation of scale can be prevented. Further, even when scale is generated on the film surface, it is possible to prevent the generated scale from depositing on the film surface. Thereby, a high water recovery rate can be realized at a low treatment cost while preventing generation and deposition of scale. Therefore, it is possible to economically desalinate brackish water without lowering the membrane performance due to the scale.

In particular, it is preferable that the frequency of the vibration provided by the vibration generator is 5 Hz or more and 100 Hz or less. Thereby, it is possible to sufficiently prevent generation of scale and deposition of scale on the film surface without damaging the film.

Further, in the brine desalination apparatus according to the first and second aspects of the present invention, the reverse osmosis membrane module preceding the at least one reverse osmosis membrane module concentrates the supply water to a concentration immediately before the scale is generated. Is preferred.
As a result, generation of scale can be prevented more efficiently.

The multistage reverse osmosis membrane module has a pH of 6.
5 with an aqueous solution having a salt concentration of 0.15%
It is preferable that the salt rejection ratio after the operation at 30 ° C. and the operation pressure of 15 kgf / cm ² for 30 minutes is such that the salt rejection is 30% or more. Thereby, it becomes possible to remove harmful substances in raw water effectively.

The reverse osmosis membrane of the multiple-stage reverse osmosis membrane module is preferably made of a polyamide membrane or a polyvinyl alcohol membrane. As a result, the ability to stop harmful substances such as arsenic, fluorine, nitrogen, pesticides, and trihalomethane is enhanced.

[0021] The brine desalination method according to a third aspect of the present invention is a method for desalination of brine using a reverse osmosis membrane module connected in a plurality of stages. Of the reverse osmosis membrane module from the permeated water side.

In the brine desalination method, backwashing is performed on at least one of the second and subsequent reverse osmosis membrane modules to prevent scale generated on the membrane surface from depositing on the membrane surface. Can be. Thereby, a high water recovery rate can be realized while preventing deposition of scale at a low processing cost. Therefore, it is possible to economically desalinate brackish water without lowering the membrane performance due to the scale.

The backwash is preferably performed periodically. As a result, it is possible to prevent scale deposition and maintain a high water recovery rate.

[0024] A fourth aspect of the present invention is a method for desalination of brine using a reverse osmosis membrane module connected in a plurality of stages, wherein at least one of the second and subsequent stages of the plurality of stages is used. Of the reverse osmosis membrane module.

In this brine desalination method, by vibrating the second and subsequent at least one reverse osmosis membrane module, aggregation of scale components can be prevented, and generation of scale can be prevented. Further, even when scale is generated on the film surface, it is possible to prevent the generated scale from depositing on the film surface. Thereby, a high water recovery rate can be realized at a low treatment cost while preventing generation and deposition of scale. Therefore, it is possible to economically desalinate brackish water without lowering the membrane performance due to the scale.

In particular, the frequency of the vibration is 5 Hz or more and 100
Hz or less. Thereby, it is possible to sufficiently prevent generation of scale and deposition of scale on the film surface without damaging the film.

In the brine desalination methods according to the third and fourth aspects of the present invention, the supply water is concentrated to a concentration immediately before the generation of scale by the reverse osmosis membrane module preceding the at least one reverse osmosis membrane module. Is preferred. As a result, generation of scale can be prevented more efficiently.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic diagram showing an example of a brine desalination apparatus according to the present invention. Hereinafter, the desalination apparatus of FIG. 1 and the desalination method using the same will be described.

In FIG. 1, raw water is supplied to a pretreatment device 1. In the pretreatment device 1, raw water is subjected to pretreatment such as coagulation sedimentation sand filtration, coagulation filtration, microfiltration, ultrafiltration, and the like. This pretreatment is performed to protect the membrane surface of the reverse osmosis membrane module from adhesion and contamination of suspended substances and organic substances.

The raw water pretreated by the pretreatment device 1 is
First stage reverse osmosis membrane module 3 using high pressure pump 2
a to the raw water inlet. Alternatively, the water pretreated by the pretreatment device 1 may be temporarily stored in the tank 7A and then supplied to the raw water inlet of the first reverse osmosis membrane module 3a by the high-pressure pump 2.

The first and second reverse osmosis membrane modules 3a and 3b concentrate the raw water to a concentration immediately before the generation of scale. Second stage reverse osmosis membrane module 3b
The concentrated water discharged from the concentrated water outlet is supplied to the raw water inlet of the reverse osmosis membrane module 3c of the third stage, and concentrated until the total water recovery rate becomes 80% or more, preferably 90% or more. The concentrated water discharged from the concentrated water outlet of the third-stage reverse osmosis membrane module 3c is discharged out of the system through the concentrated water pipe 31.

The permeated water discharged from the permeated water outlets of the first-stage, second-stage, and third-stage reverse osmosis membrane modules 3a, 3b, and 3c is supplied to the permeated water pipes 30a, 30b, and 30c, respectively.
It is stored in tank 7B through 30c, and is supplied as drinking water as needed.

In this way, the permeated water is stored in the tank 7B while the raw water is concentrated until the total water recovery rate becomes 80% or more, preferably 90% or more, and the concentrated water is discharged out of the system.

On the side of the permeated water outlet of the third-stage reverse osmosis membrane module 3c, a backwashing mechanism 5 comprising a pump 9 and valves 10, 11 is provided. During the normal operation described above, the valve 10 is opened and the valve 11 is closed. Thereby, the permeated water discharged from the permeated water outlet of the third-stage reverse osmosis membrane module 3c is supplied to the permeated water pipe 30c and the valve 1
0 and supplied to and stored in the tank 7B.

In order to prevent the scale generated on the membrane surface of the third stage reverse osmosis membrane module 3c from depositing on the membrane surface, a part of the permeated water stored in the tank 7B is used.
Backwashing is periodically performed from the permeated water side to the raw water side of the third-stage reverse osmosis membrane module 3c.

During backwashing, the valve 10 is closed and the valve 11 is opened. Then, the permeated water stored in the tank 7B is supplied by the pump 9 from the permeated water side of the third reverse osmosis membrane module 3c at a pressure of 0.1 to 5 kgf / cm ² for 1 to 10 minutes. This backwashing is performed, for example, once every 0.5 to 24 hours.

The first, second and third reverse osmosis membrane modules 3a, 3b and 3c have a pH of 6.5.
Osmosis membrane having a performance of obtaining a salt rejection of 30% or more after operating for 30 minutes at a temperature of 25 ° C. and an operating pressure of 15 kgf / cm ^{2 using} an aqueous solution having a salt concentration of 0.15% prepared as a stock solution. Use modules. If the salt rejection is less than 30%, the harmful substances in the raw water cannot be effectively removed, resulting in lack of practicality.

As the material of the reverse osmosis membrane of the reverse osmosis membrane modules 3a, 3b, 3c, acetyl cellulose, polyamide, polyvinyl alcohol and the like can be used. Use polyamide or polyvinyl alcohol which has high blocking performance of the substance.

The reverse osmosis membrane modules 3a, 3b, 3
As a form of the reverse osmosis membrane of c, an asymmetric membrane, a composite membrane or the like can be used. Further, the reverse osmosis membrane modules 3a,
As the module structure of 3b, 3c, spiral type,
Hollow fiber type, Tuppler type, plate and frame type and the like can be used. In particular, in desalination of brackish water, it is preferable to use a spiral type.

In this brine desalination apparatus, the backwashing mechanism 5 periodically performs backwashing from the permeated water side to the third-stage reverse osmosis membrane module 3c, so that the scale generated on the membrane surface is reduced. Deposition on the surface can be prevented. Thereby, deposition of scale can be prevented at a low treatment cost, and a high water recovery rate can be realized.

Therefore, when this brine desalination apparatus is used, in the desalination treatment of brine such as river water, well water, tap water, industrial water, etc., the water recovery rate is 80% or more, preferably 90%.
%, And economical and practical operation can be performed without causing deterioration of membrane performance due to scale.

In the above example, the backwashing mechanism 5 is provided in the third-stage reverse osmosis membrane module 3c. However, the backwashing mechanism 5 may be provided in the second-stage reverse osmosis membrane module 3b. Alternatively, it may be provided in the second and third reverse osmosis membrane modules 3b and 3c.

FIG. 2 is a schematic diagram showing another example of the brine desalination apparatus according to the present invention. Hereinafter, the desalination apparatus of FIG. 2 and the desalination method using the same will be described.

The brackish water desalination apparatus and the brackish water desalination method of FIG. 2 are different from the brackish water desalination apparatus and the brackish water desalination method of FIG. 1 in the following points. The third-stage reverse osmosis membrane module 3c is provided with a vibration generator 12 for generating vibration of a specific frequency instead of the backwashing mechanism 5 of FIG.
Vibration is applied to the third-stage reverse osmosis membrane module 3c by the vibration generator 12.

If the frequency of the vibration provided by the vibration generator 12 is lower than 5 Hz, the effect of preventing scale is small, and if the frequency is higher than 100 Hz, the film is damaged. Therefore, the specific frequency is 5-10
Preferably, it is 0 Hz. In order to maximize the effect, it is more preferable that the specific frequency is 50 to 100 Hz.

Also in this brine desalination apparatus, the raw water is concentrated by the first and second reverse osmosis membrane modules 3a and 3b to a concentration immediately before the generation of scale.
The concentrated water discharged from the concentrated water outlet of the second-stage reverse osmosis membrane module 3b is supplied to the third-stage reverse osmosis membrane module 3c.
And concentrated until the total water recovery rate becomes 80% or more, preferably 90% or more. The concentrated water discharged from the concentrated water outlet of the third-stage reverse osmosis membrane module 3c is discharged out of the system through the concentrated water pipe 31.

The permeated water discharged from the permeated water outlets of the first-stage, second-stage, and third-stage reverse osmosis membrane modules 3a, 3b, and 3c are the permeated water pipes 30a, 30b, and 30c, respectively.
It is stored in tank 7B through 30c, and is supplied as drinking water as needed.

Thus, the permeated water is stored in the tank 7B while the raw water is concentrated until the total water recovery rate becomes 80% or more, preferably 90% or more, and the concentrated water is discharged out of the system.

In this brine desalination apparatus, vibration of a specific frequency is applied to the third reverse osmosis membrane module 3c by the vibration generator 12 to prevent aggregation of scale components and generate scale. Can be prevented. Further, even when scale is generated on the film surface, it is possible to prevent the generated scale from depositing on the film surface. Thereby, scale generation and deposition can be prevented at a low treatment cost, and a high water recovery rate can be realized.

Therefore, when the desalination apparatus is used, in the desalination treatment of river water, well water, tap water, industrial water, etc., the water recovery rate is 80% or more, preferably 90%.
%, And economical and practical operation can be performed without causing deterioration of membrane performance due to scale.

The performance, the form and the module structure of the reverse osmosis membrane modules 3a, 3b, 3c of the first, second and third stages are the same as those of the brine desalination apparatus of FIG. is there.

In the above example, the vibration generator 12 is provided in the third-stage reverse osmosis membrane module 3c. However, the vibration generator 12 may be provided in the second-stage reverse osmosis membrane module 3b. Alternatively, it may be provided in the second and third reverse osmosis membrane modules 3b and 3c.

Further, the backwashing mechanism 5 of FIG. 1 may be provided in the brine desalination apparatus of FIG. In this case, generation of scale and deposition of scale on the film surface can be more sufficiently prevented.

[0054]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples.

[Example 1] Desalination of well water was performed using the brine desalination apparatus shown in FIG. First-stage, second-stage and third-stage reverse osmosis membrane modules 3a, 3b, 3
As c, a spiral type reverse osmosis membrane module made of polyamide [ES20 manufactured by Nitto Denko Corporation] was used. This spiral reverse osmosis membrane module has a pH
The salt rejection measured after running for 30 minutes at 25 ° C. and an operating pressure of 15 kgf / cm ^{2 using} an aqueous solution having a salt concentration of 0.15% adjusted to 6.5 as a stock solution was 9%.
It has a performance of 9.7%.

Well water having a silica concentration of 16 ppm and a water temperature of 15 ° C. is pretreated by coagulation filtration in the pretreatment device 1, and the pretreated water is subjected to the first and second reverse osmosis membrane modules 3 a, 3b and treated until the water recovery rate reaches 75%.
The water is supplied to the reverse osmosis membrane module 3c at the stage and the water recovery rate is 90%.
%.

The third-stage reverse osmosis membrane module 3c was placed at a pressure of 0.5 kgf / cm from the permeated water side once every 6 hours.
Backwashing with permeated water was performed by pump 9 for 5 minutes at ² . As a result, it was possible to operate with stable performance without generating silica scale.

Comparative Example 1 Well water was desalted using the brine desalination apparatus shown in FIG. First-stage, second-stage and third-stage reverse osmosis membrane modules 3a, 3b, 3
As c, a spiral reverse osmosis membrane module [ES20 manufactured by Nitto Denko Corporation] having a membrane material made of polyamide and having the same performance as in Example 1 was used.

Well water having a silica concentration of 16 ppm and a water temperature of 15 ° C. is pretreated by coagulation filtration in the pretreatment device 1, and the pretreated water is subjected to the first to third reverse osmosis membrane modules 3 a,
3b and 3c, and treated until the water recovery rate became 90%. As a result, silica scale was generated, and the amount of permeated water was reduced to 60% of the initial amount.

From the results of Comparative Example 1, when backwashing is not performed on the third-stage reverse osmosis membrane module 3c, a scale is generated when the water recovery rate is 90%, and the membrane performance is deteriorated. I understand. On the other hand, from the result of Example 1,
It can be seen that, when the reverse osmosis membrane module 3c of the third stage is regularly backwashed, no scale is generated even when the water recovery rate is 90%, and the membrane performance does not decrease. Therefore, the desalination process using the desalination apparatus of FIG.
Economical and practical.

Example 2 Desalination of well water was carried out using the brine desalination apparatus shown in FIG. First-stage, second-stage and third-stage reverse osmosis membrane modules 3a, 3b, 3
As c, a spiral type reverse osmosis membrane module made of polyamide [ES20 manufactured by Nitto Denko Corporation] was used. This spiral reverse osmosis membrane module has a pH
A 0.15% aqueous solution of sodium chloride adjusted to 6.5 was used as a stock solution and operated at a temperature of 25 ° C. and an operating pressure of 15 kgf / cm ² for 30 minutes.
It has a performance of 9.7%.

Well water having a silica concentration of 16 ppm and a water temperature of 15 ° C. is pretreated by coagulation filtration in the pretreatment device 1, and the pretreated water is subjected to the first and second reverse osmosis membrane modules 3 a, 3b and treated until the water recovery rate reaches 75%.
The water recovery rate is 93
%.

At this time, a vibration of 80 Hz was applied to the third reverse osmosis membrane module 3c by the vibration generator 12. As a result, it was possible to operate with stable performance without generating silica scale.

Comparative Example 2 Desalination of well water was performed using the brine desalination apparatus shown in FIG. First-stage, second-stage and third-stage reverse osmosis membrane modules 3a, 3b, 3
As c, a spiral reverse osmosis membrane module [ES20 manufactured by Nitto Denko Corporation] having a membrane material made of polyamide and having the same performance as in Example 2 was used.

Well water having a silica concentration of 16 ppm and a water temperature of 15 ° C. is pretreated by coagulation filtration in the pretreatment device 1, and the pretreated water is subjected to the first to third stage reverse osmosis membrane modules 3 a,
3b and 3c, and treated until the water recovery rate became 93%. As a result, silica scale was generated, and the amount of permeated water was reduced to the initial 40%.

Comparative Example 3 Well water was desalted using the brine desalination apparatus shown in FIG. First-stage, second-stage and third-stage reverse osmosis membrane modules 3a, 3b, 3
As c, a spiral reverse osmosis membrane module [ES20 manufactured by Nitto Denko Corporation] having a membrane material made of polyamide and having the same performance as in Example 2 was used.

Well water having a silica concentration of 16 ppm and a water temperature of 25 ° C. is pre-treated by coagulation filtration in the pre-treatment device 1, and the pre-treated water is treated with a scale component removal treatment device 8 as an algo-scientific as a silica scale inhibitor. (ARGO
SCIENTIFIC) HYPERSPE
After injecting 2 mg / L of RSE-SI300, it was supplied to the first to third reverse osmosis membrane modules 3a, 3b, 3c, and treated until the water recovery rate became 93%. As a result, silica scale was generated and the amount of permeated water was reduced to 60% of the initial value.
Down to

From the results of Comparative Example 2, when no vibration is applied to the third reverse osmosis membrane module 3c, a scale is generated when the water recovery rate is 93%, and the membrane performance may be deteriorated. Recognize. Further, from the results of Comparative Example 3, even if the processing for removing the scale-causing component is performed before the processing by the first to third-stage reverse osmosis membrane modules 3a, 3b, and 3c,
When no vibration is applied to the third reverse osmosis membrane module 3c, a scale is generated when the water recovery rate is set to 93%.
It can be seen that the film performance decreases.

On the other hand, from the results of Example 2, the third
When a vibration having a specific frequency is given to the reverse osmosis membrane module 3c at the stage, no scale is generated even when the water recovery rate is 93%, and it is understood that the membrane performance does not decrease. Therefore, the desalination process using the desalination apparatus of FIG.
Economical and practical.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a brine desalination apparatus according to the present invention.

FIG. 2 is a schematic diagram showing another example of a brine desalination apparatus according to the present invention.

FIG. 3 is a schematic diagram showing an example of a conventional brine desalination apparatus.

FIG. 4 is a schematic view showing another example of a conventional brine desalination apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pre-processing apparatus 2 High pressure pump 3a, 3b, 3c Reverse osmosis membrane module 5 Backwash mechanism 7A, 7B Tank 9 Pump 10, 11 Valve 12 Vibration generator

Continued on the front page (51) Int.Cl. ⁶ Identification code FI B01D 65/08 B01D 65/08

Claims (8)

[Claims] 1. A desalination apparatus for desalinating water using a reverse osmosis membrane module connected in a plurality of stages, wherein at least one of the second and subsequent reverse osmosis membrane modules of the plurality of stages includes a permeate side. A desalination apparatus comprising a backwashing mechanism for performing backwashing from water. 2. A desalination apparatus for desalinating water using a reverse osmosis membrane module connected in a plurality of stages, wherein vibration is applied to at least one of the second and subsequent reverse osmosis membrane modules in the plurality of stages. A brine desalination apparatus comprising a vibration generator. 3. The desalination apparatus according to claim 2, wherein the frequency of the vibration provided by the vibration generator is 5 Hz or more and 100 Hz or less. 4. The reverse osmosis membrane module preceding the at least one reverse osmosis membrane module concentrates the supply water to a concentration immediately before the scale is generated. Brine desalination equipment. 5. The multi-stage reverse osmosis membrane module, wherein:
H6.5 is used as an undiluted solution having a salt concentration of 0.15%, and has a performance of having a salt rejection of 30% or more after being operated at a temperature of 25 ° C. and an operating pressure of 15 kgf / cm ² for 30 minutes. Item 5. A brine desalination apparatus according to any one of Items 1 to 4. 6. A desalination method in which desalination is performed using a reverse osmosis membrane module connected in a plurality of stages, wherein at least one of the second and subsequent reverse osmosis membrane modules of the plurality of stages includes a permeate side. A method for desalination of brine, comprising performing backwashing from water. 7. A brine desalination method in which desalination of brine is performed using a plurality of reverse osmosis membrane modules connected to each other, wherein vibration is applied to at least one of the second and subsequent reverse osmosis membrane modules of the plurality of stages. A method for desalination of brine, comprising: 8. The method for desalination of brine according to claim 7, wherein the feedwater is concentrated to a concentration immediately before the generation of scale by the reverse osmosis membrane module at the preceding stage of the at least one reverse osmosis membrane module.