JP2012170880A - Sea water desalination system, and sea water desalination method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sea water desalination system which can reduce energy for producing plain water and which can secure the quality of water in plain water to be produced.SOLUTION: The sea water desalination system 1 includes a sewage type reverse osmosis membrane treatment means 10 to produce sewage type permeated water W11 and sewage type concentrated water W12 by conducting the membrane separation treatment of sewage W10, and a sea water type reverse osmosis membrane treatment means 20 which produces sea water type permeated water W21 and sea water type concentrated water W22 by conducting the membrane separation treatment of a mixture of the sewage type concentrated water W12 and intake sea water W20 and which has an EC meter 230 for sea water type permeated water W21 to measure the salinity of the sea water type permeated water W21. The system supplies the sea water type permeated water W21 to the sewage type reverse osmosis membrane treatment means 10 in accordance with the salinity of the sea water type permeated water W21.

Description

  The present invention relates to a seawater desalination system and a seawater desalination method.

  2. Description of the Related Art Conventionally, seawater desalination apparatuses that generate fresh water by membrane separation treatment of seawater are known. Since this seawater desalination apparatus pressurizes seawater for membrane separation and pumps it to the reverse osmosis membrane unit with a pump or the like, the higher the salt concentration of seawater, the more energy is required.

Therefore, a first treatment unit that separates sewage having a lower salinity than seawater into a membrane and separates it into permeate and concentrated water, and the concentrated water generated in the first treatment unit is mixed with seawater for dilution. A seawater desalination system comprising: a second processing unit that separates the mixed water into a permeated water and a concentrated water, and controls the first processing unit and the second processing unit based on an inflow amount of sewage Has been proposed (see Patent Document 1).
According to the seawater desalination system of Patent Document 1, by performing membrane separation on mixed water obtained by mixing sewage concentrated water with seawater, the salinity of the mixed water can be reduced if the amount of inflow of sewage increases. Compared with the case where seawater is subjected to membrane separation treatment, energy for generating fresh water can be reduced.

Japanese Patent No. 4499835

  However, since the seawater desalination system described in Patent Document 1 controls the first processing unit and the second processing unit based on the inflow amount of sewage, the quality of the generated fresh water depends on the inflow amount of sewage. Become. Here, since the sewage is drained after the organic wastewater containing organic matter or the inorganic wastewater from the manufacturing plant is filtered, etc., its water quality and quantity are not stably supplied. Absent. For this reason, it is difficult for the seawater desalination system described in Patent Document 1 to ensure water quality in the fresh water to be generated.

  An object of this invention is to provide the seawater desalination system which can reduce the energy for producing | generating fresh water and can ensure water quality in the produced fresh water.

  (1) Membrane separation treatment of mixed water of sewage reverse osmosis membrane treatment means for producing sewage permeate and sewage concentrate by subjecting sewage to membrane separation, and seawater taken from the sewage concentrate A seawater system reverse osmosis membrane treatment means having a salinity concentration measuring means for generating a seawater system permeate and a seawater system concentrated water and measuring a salt concentration of the seawater system permeate. A seawater desalination system, characterized in that the seawater permeate is supplied to the sewage reverse osmosis membrane treatment means in accordance with the salinity concentration of water.

  According to the invention of (1), the sewage reverse osmosis membrane treatment means generates sewage permeate and sewage concentrate by subjecting the sewage to membrane separation treatment. Seawater-based reverse osmosis membrane treatment means generates seawater-based permeated water and seawater-based concentrated water by membrane separation treatment of mixed water of sewage-type concentrated water and taken seawater. It has a salinity concentration measuring means for measuring. The seawater permeate is supplied to the sewage reverse osmosis membrane treatment means according to the salinity concentration of the seawater permeate.

As a result, in the seawater system reverse osmosis membrane treatment means, the mixed water of sewage concentrated water and seawater whose salinity is lower than that of seawater is subjected to membrane separation treatment to produce seawater system permeate which is fresh water. Compared with the case where high seawater is subjected to membrane separation treatment to produce fresh water, energy for producing fresh water can be reduced.
Also, for example, when the amount of sewage decreases, the amount of sewage permeated water and sewage concentrated water generated by the sewage reverse osmosis membrane treatment means decreases, and the salinity of seawater permeated water increases. However, seawater-based permeated water whose salinity is a predetermined reference value is obtained by subjecting seawater-based permeated water having increased salinity to membrane separation using a sewage reverse osmosis membrane processing means whose operating rate has decreased. Can be secured.
Therefore, it is possible to provide a seawater desalination system capable of reducing energy for generating fresh water and ensuring water quality in the generated fresh water.

  (2) A seawater desalination system having sewage reverse osmosis membrane treatment means for producing sewage permeate and sewage concentrate by subjecting sewage to membrane separation, wherein the sewage concentrate and seawater taken Seawater-based reverse osmosis membrane treatment means having salt concentration measuring means for producing seawater-based permeated water and seawater-based concentrated water by subjecting the mixed water to membrane separation treatment, and measuring the salt concentration of the seawater-based permeated water; A seawater desalination system comprising: control means for controlling the driving of the sewage reverse osmosis membrane treatment means and the seawater reverse osmosis membrane treatment means according to the salinity concentration of the seawater permeate.

  According to the invention of (2), the sewage reverse osmosis membrane treatment means generates sewage permeate and sewage concentrate by subjecting the sewage to membrane separation treatment. Seawater-based reverse osmosis membrane treatment means generates seawater-based permeated water and seawater-based concentrated water by membrane separation treatment of mixed water of sewage-based concentrated water and seawater, and measures the salinity concentration of this seawater-based permeated water A salinity concentration measuring means. The control means controls the sewage reverse osmosis membrane treatment means and the seawater reverse osmosis membrane treatment means in accordance with the salinity concentration of the seawater permeate.

As a result, in the seawater system reverse osmosis membrane treatment means, the mixed water of sewage concentrated water and seawater whose salinity is lower than that of seawater is subjected to membrane separation treatment to produce seawater system permeate which is fresh water. Compared with the case where high seawater is subjected to membrane separation treatment to produce fresh water, energy for producing fresh water can be reduced.
In addition, since the sewage reverse osmosis membrane treatment means and the seawater reverse osmosis membrane treatment means are controlled according to the salinity of the seawater permeated water that is the generated fresh water, for example, the salinity of the seawater permeated water is a predetermined concentration. If it is higher than the reference value, the driving of the seawater-based reverse osmosis membrane treatment means can be suppressed and the salinity concentration of the seawater-based permeated water can be returned to a predetermined reference value.
Therefore, it is possible to provide a seawater desalination system capable of reducing energy for generating fresh water and ensuring water quality in the generated fresh water.

  (3) Second seawater system reverse osmosis membrane treatment means for membrane separation treatment of the seawater system permeate, wherein the control means is responsive to the salt concentration of the seawater permeate measured by the salt concentration measurement means. And supplying the seawater-based permeated water to the second seawater-based reverse osmosis membrane treatment means.

According to the invention of (3), the seawater-based permeated water is further provided with a second seawater-based reverse osmosis membrane processing means.
As a result, for example, when the amount of sewage decreases, the amount of sewage permeated water and sewage concentrated water generated by the sewage reverse osmosis membrane treatment means decreases, and the salt concentration of seawater permeated water increases. However, the seawater-based permeated water whose salinity concentration is a predetermined reference value can be supplied by subjecting the seawater-based permeated water whose salinity concentration has increased to the membrane separation treatment by the second seawater-based reverse osmosis membrane processing means.

  (4) The control means supplies the seawater-based permeated water to the sewage system reverse osmosis membrane treatment means according to the salinity concentration of the seawater-based permeated water measured by the salinity concentration measuring means, and the sewage system reverse osmosis means The seawater desalination system according to (2), wherein the membrane treatment means performs membrane separation treatment on the mixed water of the seawater permeate and sewage supplied from the seawater reverse osmosis membrane treatment means.

According to the invention of (4), the seawater-based permeated water is subjected to membrane separation treatment by the sewage system reverse osmosis membrane treatment means according to the salinity concentration of the seawater-based permeated water.
As a result, for example, when the amount of sewage decreases, the amount of sewage permeated water and sewage concentrated water generated by the sewage reverse osmosis membrane treatment means decreases, and the salt concentration of seawater permeated water increases. However, by using a sewage reverse osmosis membrane treatment means whose operating rate has been reduced, the seawater permeate whose salinity is increased is subjected to membrane separation treatment, so that the seawater permeation with a predetermined salinity is performed. Can supply water.

  (5) The reverse osmosis membrane included in the seawater-based reverse osmosis membrane treatment means includes an inflow amount and a salinity concentration of sewage flowing into the sewage system reverse osmosis membrane treatment means, and an amount of seawater flowing into the seawater-based reverse osmosis membrane treatment means. A reverse osmosis membrane having a suitable desalination rate selected based on the inflow amount and the salinity concentration, and the water amount and the salinity concentration of seawater-based permeated water generated by the seawater-based reverse osmosis membrane treatment means set in advance (2) To the seawater desalination system according to any one of (4).

Here, the reverse osmosis membrane includes various membranes having a desalination rate of about 55% to about 99%. In the reverse osmosis membrane treatment means, in general, the higher the desalination rate of the reverse osmosis membrane, the higher the capacity of the lift and the need for more energy.
According to the invention of (5), the inflow amount and the salinity concentration of the sewage system and the seawater system reverse osmosis membrane treatment means, the water amount and the salinity concentration of the seawater system permeated water generated by the preset seawater system reverse osmosis membrane treatment means Therefore, by selecting a reverse osmosis membrane having a suitable desalination rate, it becomes possible to use a pump with suitable energy efficiency, and energy for generating fresh water can be further reduced.

  (6) Sewage reverse osmosis membrane treatment means for producing sewage permeate and sewage concentrate by subjecting sewage to membrane separation; seawater permeate and seawater concentrate by subjecting seawater to membrane separation Seawater-based reverse osmosis membrane treatment means for generating the above, a storage tank for storing the mixed permeated water in which the sewage-based permeated water and the seawater-based permeated water are mixed, and the level of the mixed permeated water stored in the storage tank And a storage system having a water level meter for measuring the seawater desalination system for starting or stopping the seawater system reverse osmosis membrane processing means according to the water level measured by the water level meter.

  According to the invention of (6), the sewage reverse osmosis membrane treatment means generates sewage permeate and sewage concentrate by subjecting the sewage to membrane separation treatment. The seawater-based reverse osmosis membrane processing means generates seawater-based permeated water and seawater-based concentrated water by subjecting seawater to membrane separation. The storage system includes a storage tank that stores mixed permeated water in which sewage permeated water and seawater-based permeated water are mixed, and a water level meter that measures the water level of the mixed permeated water stored in the storage tank. And a storage system starts or stops a seawater system reverse osmosis membrane process means according to the water level of the mixed permeated water measured with the water level meter.

As a result, in the seawater system reverse osmosis membrane treatment means, the mixed water of sewage concentrated water and seawater whose salinity is lower than that of seawater is subjected to membrane separation treatment to produce seawater system permeate which is fresh water. Compared with the case where high seawater is subjected to membrane separation treatment to produce fresh water, energy for producing fresh water can be reduced.
Further, since the seawater system reverse osmosis membrane treatment means is started or stopped according to the water level in the mixed permeated water storage tank in which the sewage system permeated water and the seawater system permeated water, which are generated fresh water, are mixed, When the water-based permeated water is sufficiently generated and a desired amount of water can be secured, the seawater-based reverse osmosis membrane treatment means that requires more energy than the sewage-type reverse osmosis membrane treatment means can be stopped.
Therefore, it is possible to provide a seawater desalination system that can reduce energy for generating fresh water and can secure a desired amount of water in the generated fresh water.

  (7) The storage system includes a first salinity concentration measuring unit that measures a salt concentration of the mixed permeated water stored in the storage tank, and the sewage system reverse osmosis membrane processing unit generates the generated sewage system permeation. The seawater-based reverse osmosis membrane treatment means has a third salinity-measuring means for measuring the salt concentration of the generated seawater-based permeated water. The seawater desalination system according to (6), which starts or stops according to the salinity concentration of the seawater-based permeated water, the salinity concentration of the sewage-based permeated water, and the salt concentration of the mixed permeated water.

According to the invention of (7), the seawater-based reverse osmosis membrane treatment means starts or stops according to the salinity concentration of the seawater-based permeated water, the salinity concentration of the sewage-based permeated water, and the salinity concentration of the mixed permeated water. For example, if either the salinity of the sewage permeated water or the salinity of the mixed permeated water is higher than a predetermined reference value, the mixed permeated water that is the generated fresh water is stopped by stopping the seawater-based reverse osmosis membrane treatment means. The salinity can be returned to within a predetermined reference value.
Therefore, it is possible to provide a seawater desalination system capable of reducing energy for generating fresh water and ensuring water quality in the generated fresh water.

(8) Membrane separation treatment of a mixed water of a sewage system reverse osmosis membrane treatment step for producing sewage system permeate and sewage system concentrated water by subjecting the sewage to membrane separation treatment, and the seawater taken from the sewage system concentrated water A seawater-based reverse osmosis membrane treatment step for generating seawater-based permeated water and seawater-based concentrated water, a salinity concentration measuring step for measuring the salinity concentration of the seawater-based permeated water, and the salinity concentration of the seawater-based permeated water And a seawater permeate circulating step for returning the seawater permeate to the sewage reverse osmosis membrane treatment step in accordance with the seawater desalination method.
According to invention of (8), there exists an effect similar to invention of (1).

(9) A seawater desalination method having a sewage reverse osmosis membrane treatment step for producing sewage permeate and sewage concentrate by subjecting sewage to membrane separation, and the seawater taken from the sewage concentrate A seawater-based reverse osmosis membrane treatment step for producing seawater-based permeated water and seawater-based concentrated water by subjecting the mixed water to membrane separation treatment, and a salinity concentration measuring step for measuring the salt concentration of the seawater-based permeated water, A seawater desalination method comprising: a sewage reverse osmosis membrane treatment step and a continuation determination step that decides continuation of the seawater reverse osmosis membrane treatment step according to the salinity of the seawater permeate. .
According to invention of (9), there exists an effect similar to invention of (2).

(10) The seawater system permeated water is further provided with a second seawater system reverse osmosis membrane treatment step for membrane separation treatment, and the seawater system permeation is performed according to the salt concentration of the seawater system permeated water measured in the salt concentration measurement step. The seawater desalination method according to (9), wherein water is treated in the second seawater-based reverse osmosis membrane treatment step.
According to invention of (10), there exists an effect similar to invention of (3).

(11) A seawater-based permeate circulation step for returning the seawater-based permeate to the sewage reverse osmosis membrane treatment step according to the salt concentration of the seawater-based permeate measured in the salt concentration measurement step, The aqueous reverse osmosis membrane treatment step is a seawater desalination method according to (9), wherein the mixed water of the seawater permeate and sewage returned in the seawater permeate circulation step is subjected to membrane separation treatment.
According to invention of (11), there exists an effect similar to invention of (4).

(12) A sewage reverse osmosis membrane treatment step for producing sewage permeate and sewage concentrate by subjecting sewage to membrane separation; and seawater permeate and seawater concentrate by subjecting seawater to membrane separation. A seawater-based reverse osmosis membrane treatment step for generating a sewage-based permeated water and a mixed permeated water in which the seawater-based permeated water is mixed and stored in a storage tank, and the mixture stored in the storage tank A seawater desalination method comprising: a water level measurement step for measuring the level of permeate water; and a determination step for determining whether or not to perform the seawater system reverse osmosis membrane treatment step according to the water level measured in the water level measurement step. .
According to invention of (12), there exists an effect similar to invention of (6).

(13) A first salinity concentration measuring step for measuring a salinity concentration of the mixed permeated water stored in the storage tank, and a first salinity concentration of the sewage permeated water generated in the sewage reverse osmosis membrane treatment step. 2 and a third salinity measurement step for measuring the salinity of the seawater-based permeated water generated in the seawater-based reverse osmosis membrane treatment step. The seawater fresh water according to (12), wherein whether or not to perform the seawater-based reverse osmosis membrane treatment step is determined according to the salinity of permeated water, the salinity of the sewage permeated water, and the salinity of the mixed permeated water. Method.
According to the invention of (13), the same effect as that of the invention of (7) is achieved.

  ADVANTAGE OF THE INVENTION According to this invention, while reducing the energy for producing | generating fresh water, the seawater desalination system which can ensure water quality in the produced fresh water can be provided.

It is a schematic structure figure showing the seawater desalination system of a 1st embodiment of the present invention. It is a schematic block diagram which shows the seawater desalination system of the modification of 1st Embodiment of this invention. It is a schematic block diagram which shows the seawater desalination system of 2nd Embodiment of this invention.

<First Embodiment>
With reference to FIG. 1, the seawater desalination system 1 of 1st Embodiment of this invention is demonstrated. FIG. 1 is a schematic configuration diagram showing a seawater desalination system 1 according to a first embodiment of the present invention.

As shown in FIG. 1, the seawater desalination system 1 according to the first embodiment includes a sewage reverse osmosis membrane treatment means 10, a seawater reverse osmosis membrane treatment means 20, and a control means 100. This is a device that generates a sewage permeate W11 and a seawater permeate W21 that are fresh water by subjecting W10 and seawater W20 to membrane separation.
Seawater W20 in this specification is water that exists in the sea, lake, swamp, pond, etc., and has a salinity of about 1.0 mass% or more and about 4.0 mass% or less. Moreover, the sewage W10 in this specification is drained after organic wastewater containing organic matter, inorganic wastewater from a manufacturing plant, etc. is filtered, etc., and has a lower salinity than seawater W20. It is. Moreover, the fresh water in this specification is water with low salt concentration.

The seawater desalination system 1 is a sewage reverse osmosis membrane treatment means 10 that generates sewage permeate W11 and sewage concentrate W12 by membrane separation of the sewage W10, and seawater taken by the sewage concentrate W12. A seawater-based permeated water W21 and seawater-based concentrated water W22 are generated by subjecting the mixed water with W20 to membrane separation, and a conductivity meter (hereinafter referred to as an EC meter) that measures the salinity concentration of the seawater-based permeated water W21. Seawater-based reverse osmosis membrane treatment means 20 having 230),
And control means 100 for controlling the driving of the sewage reverse osmosis membrane treatment means 10 and the seawater reverse osmosis membrane treatment means 20 according to the salinity concentration of the seawater permeate W21.

The seawater desalination system 1 supplies the seawater permeate W21 to the supply system and supplies it if the salinity concentration of the seawater permeate W21 satisfies a standard that can flow out to a supply system (not shown) that uses the permeate. When the standard that can flow into the system is not satisfied, the seawater-based permeated water W21 is circulated to the sewage system reverse osmosis membrane treatment means 10.
Hereinafter, each structure of the seawater desalination system 1 is demonstrated in detail.

The sewage reverse osmosis membrane treatment means 10 includes a sewage line L10 that supplies sewage W10 from outside the system, a sewage pretreatment module 11 that is provided in the sewage line L10 and filters sludge contained in the sewage W10, and a sewage line L10. And a sewage reverse osmosis membrane module 12 for producing a sewage permeate W11 and a sewage concentrate W12, and upstream of the sewage reverse osmosis membrane module 12 in the sewage line L10. And a sewage system permeate line L11 connected to the sewage system reverse osmosis membrane module 12, and a sewage system concentrated water line L12 connected to the sewage system reverse osmosis membrane module 12. Prepare.
The “line” in the present specification is a line through which fluid can flow, and includes a flow path, a path, a pipe line, and the like.

  The sewage line L10 extends from outside the seawater desalination system 1 and is connected to the sewage system reverse osmosis membrane module 12 via the sewage system pretreatment module 11, and sludge is removed by the sewage system pretreatment module 11. The sewage W10 is introduced into the sewage reverse osmosis membrane module 12.

  The sewage pretreatment module 11 is provided on the upstream side of the sewage reverse osmosis membrane module 12 in the sewage line L10, and filters and removes sludge contained in the sewage W10 by a membrane separation activated sludge method. In the present embodiment, the sewage pretreatment module 11 includes a microfiltration membrane or an ultrafiltration membrane (not shown) as a filtration medium. In this embodiment, the sewage system pretreatment module 11 uses a microfiltration membrane or an ultrafiltration membrane. However, the present invention is not limited to this, and other filtration devices that remove sludge contained in the sewage W10 are used. You can also.

The sewage reverse osmosis membrane module 12 is connected to the downstream end of the sewage line L10. The sewage system reverse osmosis membrane module 12 performs membrane separation treatment of the sewage W10 from which sludge has been removed by the sewage system pretreatment module 11 with a reverse osmosis membrane (hereinafter also referred to as “RO membrane”), and the sewage system permeate water W11 and Aqueous concentrated water W12 is produced. The sewage system reverse osmosis membrane module 12 includes one or a plurality of RO membrane elements (not shown), and these RO membrane elements remove dissolved salts in water. As the RO membrane element, a membrane having a suitable desalination rate is selected based on the inflow amount of the sewage W10 flowing into the sewage reverse osmosis membrane treatment means 10 and the salinity concentration.
The pressurization pump 13 is provided in the sewage line L10, pressurizes the sewage W10, and sends it to the sewage system reverse osmosis membrane module 12.

  The sewage system permeate water line L <b> 11 and the sewage system concentrate water line L <b> 12 are connected to the downstream side of the sewage system reverse osmosis membrane module 12. The sewage system permeate line L11 is a line through which the sewage system permeate water W11 that has permeated the RO membrane flows and drains the sewage system permeate water W11 out of the system. The sewage system concentrated water line L12 is a line through which the sewage system concentrated water W12 that has not passed through the RO membrane flows. The sewage system concentrated water line L <b> 12 is connected to the seawater system reverse osmosis membrane processing means 20 and supplies the sewage system concentrated water W <b> 12 to the seawater system reverse osmosis membrane processing means 20.

  The seawater-based reverse osmosis membrane treatment means 20 is provided with a seawater line L20 for supplying seawater W20 from outside the system, and floating bacteria (hereinafter also referred to as “bacteria, SS”) and the like included in the seawater W20. A seawater system reverse osmosis membrane that is connected to a seawater system pretreatment module 21 such as sand filtration or VF to be filtered and a seawater line L20, and membranes the seawater W20 to generate a seawater permeate W21 and a seawater concentrated water W22. In the module 22 and the seawater line L20, a pressurizing pump 23 provided on the upstream side of the seawater system reverse osmosis membrane module 22, a seawater system permeate line L21 connected to the seawater system reverse osmosis membrane module 22, and a seawater system Seawater system concentrated water line L22 connected to reverse osmosis membrane module 22, seawater system salinity measurement line L23 branched from seawater system permeated water line L21, seawater system An EC meter 230 for measuring the salinity concentration of the seawater permeated water W21 sent to the seawater permeated water line L21 via the partial concentration measuring line L23, and a seawater permeated water drainage line branched from the seawater permeated water line L21 L24 and the seawater system permeate circulation line L25 branched from the seawater system permeate line L21.

  The seawater line L20 extends from outside the seawater desalination system 1 and is connected to the seawater reverse osmosis membrane module 22 via the seawater pretreatment module 21. The seawater line L20 is connected to the sewage system concentrated water line L12 at a sewage system concentrated water line connection point J12 between the seawater system pretreatment module 21 and the seawater system reverse osmosis membrane module 22. The pressurizing pump 23 is provided in the seawater line L20, and the seawater W20 from which bacteria, SS, and the like have been removed by the seawater system pretreatment module 21, and the sewage system concentrated water W12 supplied from the sewage system reverse osmosis membrane treatment means 10. The mixed water is pressurized and sent to the seawater-based reverse osmosis membrane module 22.

  The seawater system pretreatment module 21 is provided on the upstream side of the seawater system reverse osmosis membrane module 22 in the seawater line L20, and filters and removes bacteria, SS, and viruses SS contained in the seawater W20 by membrane separation processing. In the present embodiment, the seawater system pretreatment module 21 sand-filters the seawater W20 and then performs membrane separation treatment with an ultrafiltration membrane (not shown). The seawater system pretreatment module 21 uses an ultrafiltration membrane in this embodiment. However, the present invention is not limited to this. Other than a microfiltration membrane that removes bacteria, SS, and viruses SS contained in the seawater W20, etc. It is also possible to use a filtration membrane.

  The seawater system reverse osmosis membrane module 22 is connected to the downstream side of the seawater line L20. The seawater system reverse osmosis membrane module 22 reverses the mixed water of the seawater W20 from which bacteria, SS and the like have been removed by the seawater system pretreatment module 21 and the sewage system concentrated water W12 supplied from the sewage system reverse osmosis membrane treatment means 10. Membrane separation processing is performed by the osmosis membrane to generate seawater-based permeate W21 and seawater-based concentrated water W22. The seawater-based reverse osmosis membrane module 22 includes a single or a plurality of RO membrane elements (not shown), and these RO membrane elements remove dissolved salts in water. The RO membrane element includes the inflow amount and salinity concentration of seawater W20 flowing into the seawater system reverse osmosis membrane treatment means 20, the water amount and salinity of seawater system permeated water W21 generated by the seawater system reverse osmosis membrane treatment means 20 set in advance. A membrane with a suitable desalination rate is selected based on the concentration.

The seawater system permeate line L21 and the seawater system concentrate line L22 are connected to the downstream side of the seawater system reverse osmosis membrane module 22.
The seawater-based permeated water line L21 is a line through which the seawater-based permeated water W21 that has passed through the RO membrane flows. A seawater salt concentration measurement line L23 and a seawater permeate drainage line L24 are sequentially connected from the upstream side to the seawater permeate line L21. The seawater permeate line L21 is provided with a seawater permeate circulation valve 250 at the downstream end. The seawater system permeate line L21 is connected to the seawater system permeate circulation line L25 via the seawater system permeate circulation valve 250, and the seawater system permeate W21 is circulated through the sewage system reverse osmosis membrane treatment means 10.

The seawater-based concentrated water line L22 is a line through which the seawater-based concentrated water W22 that has not permeated the RO membrane flows and drains the seawater-based concentrated water W22 out of the system.
The seawater system salinity measurement line L23 branches from the seawater system permeate line L21 at the salinity measurement line branch point J23, and the seawater system permeate W21 circulates to the seawater system permeate EC meter 230 as the salinity concentration measurement means. It is connected.
The seawater-based permeated water EC meter 230 measures the conductivity of the seawater-based permeated water W21 flowing through the seawater-based salinity concentration measurement line L23 as a salinity concentration measuring step, and converts it into a salinity concentration. The seawater-based permeated water EC meter 230 is connected to the control means 100 and transmits the measured conductivity of the seawater-based permeated water W21 or the converted salinity concentration to the control means 100.

The seawater permeate drainage line L24 branches from the seawater permeate drainage line L21 at the seawater system permeate drainage line branch point J24, and supplies the seawater permeate permeate W21 via the seawater permeate drainage valve 240 (illustrated). No line).
The seawater-based permeate drainage valve 240 is composed of an electromagnetic valve or a motor-operated valve. If the salt concentration of the seawater-based permeate W21 satisfies the standard that can flow out to the supply system under the control of the control means 100, the seawater-based permeate W21. Is configured to flow out to the supply system, and is configured to stop the seawater system permeate water W21 from flowing out to the supply system when the salinity concentration of the seawater system permeate water W21 does not satisfy the standard capable of flowing into the supply system. Has been.

The seawater permeate circulation line L25 extends from the seawater permeate circulation valve 250 and is connected to a seawater permeate circulation line connection point J26 of the sewage line L10. The seawater-based permeated water circulation line L25 is a line for circulating the seawater-based permeated water W21 to the sewage system reverse osmosis membrane treatment means 10.
The seawater-based permeate circulation valve 250 is composed of an electromagnetic valve or a motor-operated valve. If the salt concentration of the seawater-based permeate W21 satisfies a standard that can flow out to a supply system (not shown) under the control of the control means 100, the seawater-system permeate The water W21 is configured not to be circulated to the sewage system reverse osmosis membrane treatment means 10, and when the salinity concentration of the seawater system permeate W21 does not satisfy the standard capable of flowing out to the supply system, the seawater system permeate water W21 is sewage system reverse. The osmosis membrane treatment means 10 is configured to circulate.

  The control means 100 is electrically connected to the element in which control is performed among each element which comprises the seawater desalination system 1. FIG. Specifically, the control means 100 determines whether the pressure pump 13, the pressure pump 23, the seawater permeate drainage valve 240, according to the salt concentration of the seawater permeate W21 measured by the seawater permeate EC meter 230. The seawater permeate circulation valve 250 is controlled.

Next, the operation of the seawater desalination system 1 will be described.
First, the control means 100 performs control to drive the pressure pump 13 and the pressure pump 23.
As a result, the sewage reverse osmosis membrane treatment means 10 is driven, and the sewage W10 supplied from outside the system and from which sludge has been removed by the sewage pretreatment module 11 is introduced into the sewage reverse osmosis membrane module 12. The sewage W10 introduced into the sewage system reverse osmosis membrane module 12 is subjected to a membrane separation process to generate a sewage system permeated water W11 and a sewage system concentrated water W12. The sewage system permeated water W11 is drained outside the system, and the sewage system concentrated water W12 is supplied to the seawater system reverse osmosis membrane treatment means 20.
The seawater-based reverse osmosis membrane treatment means 20 is driven, and the seawater W20 supplied from outside the system and from which bacteria, SS, etc. are removed by the seawater-system pretreatment module 21 is supplied from the sewage-system reverse osmosis membrane treatment means 10. It is mixed with the sewage system concentrated water W12 and introduced into the seawater system reverse osmosis membrane module 22. The mixed water of the seawater W20 and the sewage system concentrated water W12 introduced into the seawater system reverse osmosis membrane module 22 is subjected to a membrane separation process to generate a seawater system permeated water W21 and a seawater system concentrated water W22. The seawater-based permeated water W21 flows out to the seawater-based permeated water line L21, and the seawater-based concentrated water W22 is drained out of the system.

Then, the seawater-based permeated water EC meter 230 measures the salt concentration of the seawater-based permeated water W21 that has flowed out to the seawater-based permeated water line L21 and transmits it to the control means 100.
The control means 100 performs the following processing as the continuation determination step.
When the salinity concentration of the seawater-based permeated water W21 transmitted from the seawater-based permeated water EC meter 230 satisfies the standard that can flow out to the supply system (not shown), the control means 100 is configured to supply the seawater-based permeated water drain valve 240. And the seawater-based permeate circulation valve 250 is controlled to be closed.
Thereby, seawater system permeated water W21 flows out into a supply system.

Further, when the salinity concentration of the seawater permeate W21 transmitted from the seawater permeate EC meter 230 does not satisfy the standard that allows the control unit 100 to flow out to the supply system, The permeated water circulation valve 250 is opened, the seawater-based permeated water drain valve 240 is closed, and the flow rate is reduced by lowering the output of the pressurizing pump 23.
Accordingly, the seawater-based permeated water W21 is circulated to the sewage system reverse osmosis membrane treatment means 10 via the seawater-based permeate circulation line L25, and again, the sewage system reverse osmosis membrane treatment means 10 and the seawater system reverse osmosis membrane treatment means. 20 is used for membrane separation treatment. Moreover, the amount of seawater W20 in the seawater-based reverse osmosis membrane treatment means 20 is reduced.

According to the seawater desalination system 1 of 1st Embodiment, there exist the following effects.
In the seawater system reverse osmosis membrane treatment means 20, the mixed water of the sewage system concentrated water W12 and the seawater W20 having a salinity lower than that of the seawater is subjected to a membrane separation treatment to generate a seawater system permeate W21 which is a fresh water. Compared to the case where fresh seawater W20 is produced by membrane separation treatment of high seawater W20, energy for producing fresh water can be reduced.
Further, for example, the amount of sewage W10 decreases, the amount of sewage permeated water W11 and sewage concentrated water W12 generated by the sewage system reverse osmosis membrane treatment means 10 decreases, and the salinity of seawater permeable water W21 increases. Even in this case, by using the sewage reverse osmosis membrane treatment means 10 having a reduced operating rate, the salinity permeated water W21 having increased salinity is subjected to membrane separation treatment, so that the salinity is a predetermined concentration. Seawater permeated water can be supplied.
Therefore, it is possible to provide a seawater desalination system capable of reducing energy for generating fresh water and ensuring water quality in the generated fresh water.

  Moreover, since the sewage system reverse osmosis membrane processing means 10 and the seawater system reverse osmosis membrane processing means 20 are controlled according to the salinity concentration of the seawater system permeated water W21 which is the generated fresh water, for example, the salinity of the seawater system permeate water W21 When the concentration does not satisfy the standard that can flow out to the supply system, the driving of the seawater-based reverse osmosis membrane treatment means 20 can be suppressed and the salt concentration of the seawater-based permeated water can be returned to a predetermined concentration.

  Further, the inflow amount and salinity concentration of the sewage system reverse osmosis membrane treatment means 10 and the seawater system reverse osmosis membrane treatment means 20, the water amount and salinity of the seawater system permeate W21 generated by the seawater system reverse osmosis membrane treatment means 20 set in advance. By selecting a reverse osmosis membrane having a suitable desalination rate from the concentration, it becomes possible to use a pump with suitable energy efficiency, and the energy for generating fresh water can be further reduced.

  Next, a modification of the first embodiment of the present invention will be described. About the modification of 1st Embodiment, it demonstrates centering around a different point from 1st Embodiment mainly, the same code | symbol is attached | subjected about the structure similar to 1st Embodiment, and detailed description is abbreviate | omitted. The description about the first embodiment is appropriately applied to points that are not particularly described in the modification of the first embodiment.

<Modification of First Embodiment>
With reference to FIG. 2, seawater desalination system 1 'which is a modification of 1st Embodiment is demonstrated. FIG. 2 is a schematic configuration diagram showing a seawater desalination system 1 ′ according to a modification of the first embodiment of the present invention.
The seawater desalination system 1 ′, which is a modification of the first embodiment, differs from the seawater desalination system 1 of the first embodiment in the seawater line of the seawater system reverse osmosis membrane treatment means, the seawater system permeate line, and the control means. The configuration is different. Moreover, seawater desalination system 1 'which is a modification of 1st Embodiment is provided with the 2nd seawater system reverse osmosis membrane processing means 30 which the seawater desalination system 1 of 1st Embodiment does not have.
The seawater desalination system 1 ′ causes the seawater permeate W21 to flow out to the supply system when the salinity concentration of the seawater permeate W21 satisfies a standard that can flow out to the supply system (not shown). When the standard which can flow out is not satisfied, the seawater-based permeated water W21 is further subjected to membrane separation processing in the second seawater-based reverse osmosis membrane processing means 30.

  The seawater line L20 'of the seawater system reverse osmosis membrane treatment means 20' extends from outside the seawater desalination system 1 'and is connected to the seawater system reverse osmosis membrane module 22 via the seawater system pretreatment module 21. In addition, a sewage system concentrated water line L12 is connected to the seawater line L20 ′ at a sewage system concentrated water line connection point J12 between the seawater system pretreatment module 21 and the seawater system reverse osmosis membrane module 22. The seawater-based reconcentrated water line L32 is connected at a seawater-based reconcentrated water line connecting point J32 between the line connecting point J12 and the seawater-based reverse osmosis membrane module 22.

The seawater permeate line L 21 ′ of the seawater system reverse osmosis membrane treatment means 20 ′ is connected to the downstream side of the seawater system reverse osmosis membrane module 22.
The seawater-based permeated water line L21 ′ is a line through which the seawater-based permeated water W21 that has passed through the RO membrane flows. A seawater-based salinity concentration measurement line L23 and a seawater-based permeate drainage line L24 are sequentially connected to the seawater-based permeated water line L21 ′ from the upstream side. The seawater system permeate line L21 ′ is provided with a seawater system valve 210 at the downstream end. The seawater system permeate line L21 ′ is connected to the second seawater system reverse osmosis membrane treatment means 30 via the seawater system valve 210, and supplies the seawater system permeate water W21 to the second seawater system reverse osmosis membrane treatment means 30. .

  The seawater system valve 210 is composed of an electromagnetic valve or an electric valve. When the salt concentration of the seawater system permeate W21 does not satisfy the standard that can flow out to the supply system under the control of the control unit 100, the seawater system permeate water W21 is supplied. When configured to supply the second seawater-based reverse osmosis membrane treatment means 30 and the salt concentration of the seawater-based permeated water W21 satisfies a standard capable of flowing out to the supply system, the seawater-based permeated water W21 is supplied to the supply system. It is configured to flow out.

  The second seawater system reverse osmosis membrane treatment means 30 is connected to a seawater system permeate supply line L30 for supplying seawater system permeate W21 from the seawater system reverse osmosis membrane treatment means 20 ′, and a seawater system permeate supply line L30. In the seawater system permeated water supply line L30, the second seawater system reverse osmosis membrane module 32 that further performs membrane separation treatment of the seawater system permeated water W21 to generate the seawater system repermeated water W31 and the seawater system reconcentrated water W32. A pressurizing pump 33 provided upstream from the seawater-based reverse osmosis membrane module 32, a seawater-based repermeate water line L31 connected to the second seawater-based reverse osmosis membrane module 32, and a second seawater-based reverse osmosis membrane module And a seawater-based reconcentrated water line L32 connected to 32.

  The seawater-based permeate supply line L30 extends from the seawater-system valve 210 of the seawater-system reverse osmosis membrane processing means 20 ′ and is connected to the second seawater-system reverse osmosis membrane module 32. It is introduced into the reverse osmosis membrane module 32.

The second seawater system reverse osmosis membrane module 32 is connected to the downstream side of the seawater system permeate supply line L30. The second seawater-based reverse osmosis membrane module 32 performs membrane separation processing on the seawater-based permeated water W21 having a salinity concentration exceeding a predetermined reference value by the reverse osmosis membrane, and the seawater-based repermeated water W31 and the seawater-based reconcentrated water W32 Is generated. The 2nd seawater system reverse osmosis membrane module 32 is provided with the single or some RO membrane element (not shown), and removes dissolved salt in water by these RO membrane elements. The RO membrane element includes the inflow amount and salinity of the seawater permeate W21 flowing into the second seawater system reverse osmosis membrane treatment means 30, and the seawater system generated by the preset second seawater system reverse osmosis membrane treatment means 30. A membrane having a suitable desalination rate is selected based on the amount of water and the salinity concentration of the repermeated water W31.
The pressurizing pump 33 is provided in the seawater-based permeated water supply line L30, pressurizes the seawater-based permeated water W21, and sends it to the second seawater-based reverse osmosis membrane module 32.

  The seawater repermeable water line L31 and the seawater reconcentrated water line L32 are connected to the downstream side of the second seawater reverse osmosis membrane module 32. The seawater repermeate water line L31 is a line through which the seawater repermeate water W31 that has permeated the RO membrane flows and flows out to the supply system (not shown). The seawater reconcentrated water line L32 is a line through which the seawater reconcentrated water W32 that has not permeated the RO membrane flows. The seawater-based reconcentrated water line L32 is connected to the seawater-based reverse osmosis membrane processing means 20 'and supplies seawater-based reconcentrated water W32 to the seawater-based reverse osmosis membrane processing means 20'.

  The control means 100 ′ is electrically connected to an element to be controlled among the elements constituting the seawater desalination system 1 ′. Specifically, the control means 100 ′ determines the pressurizing pump 13, the pressurizing pump 23, the pressurizing pump 33, the seawater system according to the salinity concentration of the seawater permeated water W21 measured by the seawater system permeated water EC meter 230. The valve 210 and the seawater-based permeate drainage valve 240 are controlled.

Next, operation | movement of seawater desalination system 1 'is demonstrated.
The operations until the sewage permeated water W11 and the seawater permeated water W21 are generated in the seawater desalination system 1 ′ are the same as those in the seawater desalination system 1 of the first embodiment, and thus the description thereof is omitted.

The seawater-based permeated water EC meter 230 measures the salinity concentration of the seawater-based permeated water W21 that has flowed out to the seawater-based permeated water line L21 ′ and transmits it to the control means 100 ′.
The control means 100 ′ performs the following processing as the continuation determination step.
The control means 100 ′ opens the seawater permeate drainage valve 240 when the salt concentration of the seawater permeate W21 transmitted from the seawater permeate EC meter 230 satisfies the standard capable of flowing into the supply system. Then, control for closing the seawater system valve 210 is performed.
Thereby, seawater system permeated water W21 flows out into a supply system.

Further, when the salinity concentration of the seawater-based permeated water W21 transmitted from the seawater-based permeated water EC meter 230 does not satisfy the standard that allows the control means 100 ′ to flow out to the supply system, the control means 100 ′ As a processing step, the seawater system valve 210 is opened and the pressure pump 33 is driven to control the second seawater system reverse osmosis membrane processing means 30.
As a result, the seawater-based permeated water W21 is supplied to the second seawater-based reverse osmosis membrane treatment means 30. The supplied seawater-based permeated water W21 is introduced into the second seawater-based reverse osmosis membrane module 32 and subjected to membrane separation treatment to generate seawater-based repermeated water W31 and seawater-based reconcentrated water W32. The seawater repermeated water W31 is discharged to the supply system. Since the seawater-based reconcentrated water W32 has a lower salinity than the seawater-based concentrated water W22, it is not drained out of the system and returned to the seawater-based reverse osmosis membrane treatment means 20 ′.

According to the seawater desalination system 1 ′, which is a modification of the first embodiment, the following effects can be obtained.
For example, when the amount of sewage W10 decreases and the amount of sewage permeated water W11 and sewage concentrated water W12 generated by the sewage reverse osmosis membrane treatment means 10 decreases, and the salinity of seawater permeable water W21 increases. Even so, the seawater-based permeated water W21 whose salinity concentration has been increased by the second seawater-based reverse osmosis membrane treatment means 30 can be supplied with seawater-based permeated water that satisfies the standard for the salinity concentration.

  Next, a second embodiment of the present invention will be described. The second embodiment will be described mainly with respect to differences from the first embodiment. The same components as those in the first embodiment will be denoted by the same reference numerals and detailed description thereof will be omitted. For the points not particularly described in the second embodiment, the description of the first embodiment is applied as appropriate.

Second Embodiment
With reference to FIG. 3, the seawater desalination system 1A of 2nd Embodiment is demonstrated. FIG. 3 is a schematic configuration diagram showing a seawater desalination system 1A according to a second embodiment of the present invention.
The seawater desalination system 1A according to the second embodiment is different from the seawater desalination system 1 according to the first embodiment in that the sewage system reverse osmosis membrane treatment means uses a sewage system permeate line and seawater system reverse osmosis membrane treatment means. The configuration of the water line and the control means is different. Moreover, 1 A of seawater desalination systems of 2nd Embodiment are provided with the storage system 40 which the seawater desalination system 1 of 1st Embodiment does not have.

The sewage system reverse osmosis membrane treatment means 10 </ b> A is connected to the downstream side of the sewage system reverse osmosis membrane module 12. The sewage system permeate line L11A is a line through which the sewage system permeate water W11 that has passed through the RO membrane flows. A sewage system salinity measurement line L13 and a storage system 40 are sequentially connected from the upstream side to the sewage system permeate line L11A, and the sewage system permeate water W11 is supplied to the storage system 40.
The sewage system salinity measurement line L13 branches from the sewage system permeate line L11A at the salinity system measurement line branch point J13, and the sewage system permeate W11 circulates, and the sewage system permeate EC as the second salinity concentration measurement means. A total of 130 is connected.
The sewage system permeated water EC meter 130 measures the conductivity of the sewage system permeated water W11 flowing through the sewage system salt concentration measurement line L13 as a second salinity concentration measurement step, and converts it into a salt concentration. The sewage system permeated water EC meter 130 is connected to the control unit 100A, and transmits the measured conductivity of the sewage system permeated water W11 or the converted salinity concentration to the control unit 100A.

The seawater system permeate line L21A of the seawater system reverse osmosis membrane treatment means 20A is connected to the downstream side of the seawater system reverse osmosis membrane module 22. The seawater-based permeated water line L21A is a line through which the seawater-based permeated water W21 that has passed through the RO membrane flows. A seawater-based salinity measurement line L23 and a storage system 40 are sequentially connected to the seawater-based permeated water line L21A from the upstream side, and the seawater-based permeated water W21 is supplied to the storage system 40.
The seawater-based salinity measurement line L23 branches from the seawater-based permeate line L21A at the salinity-concentration measurement line branch point J13, and the seawater-based permeate W21 circulates, and the seawater-based permeate EC as the third salinity concentration measurement means. A total of 230 is connected.
The seawater-based permeated water EC meter 230 measures the electrical conductivity of the seawater-based permeated water W21 flowing through the seawater-based salinity concentration measurement line L23 as a third salinity concentration measuring step, and converts it to a salinity concentration. The seawater-based permeated water EC meter 230 is connected to the control means 100A, and transmits the measured conductivity of the seawater-based permeated water W21 or the converted salinity concentration to the control means 100A.

  The storage system 40 is connected to the storage tank 41 connected to the sewage system permeate line L11A of the sewage system reverse osmosis membrane treatment means 10A and the seawater system permeate line L21A of the seawater system reverse osmosis membrane treatment means 20A, and to the storage tank 41. The storage tank drain line L41, the water level meter 42 for measuring the water level of the storage tank 41, the storage tank salinity concentration measurement line L43 connected to the storage tank 41, and the first tank connected to the storage tank salinity measurement line L43. Storage tank EC meter 430 as one salinity concentration measuring means.

The storage tank 41 receives mixed permeated water W40 in which the sewage system permeated water W11 supplied from the sewage system reverse osmosis membrane processing means 10A and the seawater system permeated water W21 supplied from the seawater system reverse osmosis membrane processing means 20A are mixed. Store.
The storage tank drain line L41 is a line connected to the bottom of the storage tank 41 and flowing out the mixed permeated water W40 to a supply system (not shown).
The water level meter 42 measures the water level of the mixed permeated water W40 stored in the storage tank 41. The water level meter 42 is connected to the control means 100A, and transmits the measured water level of the mixed permeated water W40 to the control means 100A. The water level gauge 42 is a pressure type water level gauge that is disposed at the bottom of the storage tank 41 and that detects a water pressure and measures the water level from a change in water pressure. A water level gauge can be used.

The storage tank salinity measurement line L43 extends to the vicinity of the bottom of the storage tank 41, the mixed permeated water W40 circulates, and is connected to the storage tank EC meter 430.
The storage tank EC meter 430 measures the conductivity of the mixed permeated water W40 flowing through the storage tank salinity concentration measurement line L43 as the first salinity concentration measurement step, and converts it into a salinity concentration. The storage tank EC meter 430 is connected to the control unit 100A, and transmits the measured conductivity of the mixed permeated water W40 or the converted salt concentration to the control unit 100A.

  100 A of control means are electrically connected to the element in which control is performed among each element which comprises seawater desalination system 1A. Specifically, the control unit 100A controls the water level of the mixed permeated water W40 measured by the water level gauge 42, the salinity concentration of the sewage permeated water W11 measured by the sewage permeated water EC meter 130, and the seawater permeated water EC meter 230. The pressurization pump 13 or the pressurization pump 23 is controlled according to the salinity concentration of the seawater-based permeated water W21 measured in step 1 or the salinity concentration of the mixed permeated water W40 measured by the storage tank EC meter 430.

Next, the operation of the seawater desalination system 1A will be described.
The operations until the sewage permeated water W11 and the seawater permeated water W21 are generated in the seawater desalination system 1A are the same as those in the seawater desalination system 1 of the first embodiment, and thus description thereof is omitted.
The sewage system permeated water W11 generated by the sewage system reverse osmosis membrane treatment means 10A and the seawater system permeable water W21 generated by the seawater system reverse osmosis membrane treatment means 20A are mixed to form a mixed permeable water W40. It is stored in the storage tank 41. The mixed permeated water W40 stored in the storage tank 41 flows out from the storage tank drain line L41 to the supply system, but the generation amount of the sewage system permeate water W11 and the seawater system permeate water W21 (the generation amount of the mixed permeate water W40) is. When it is larger than the drainage amount of the mixed permeated water W40, the mixed permeated water W40 is stored in the storage tank 41.
The water level meter 42 measures the water level of the mixed permeated water W40 stored in the storage tank 41 and transmits it to the control means 100A.

The control unit 100A performs the following processing as the determination step.
When the water level of the mixed permeated water W40 transmitted from the water level gauge 42 reaches a predetermined seawater system reverse osmosis membrane treatment means stop water level, the control unit 100A stops the pressurizing pump 23 and performs seawater system reverse osmosis membrane treatment. The driving of the means 20A is stopped.
Accordingly, the seawater desalination system 1A is in a state where only the sewage system reverse osmosis membrane treatment means 10A is driven, and only the sewage system permeated water W11 is supplied to the storage tank 41.

For example, when the production amount of the sewage system permeate water W11 (production amount of the mixed permeate water W40) becomes smaller than the drainage amount of the mixed permeate water W40, the water level of the mixed permeate water W40 in the storage tank 41 drops.
When the water level of the mixed permeated water W40 transmitted from the water level gauge 42 reaches a predetermined seawater system reverse osmosis membrane treatment means start water level, the control unit 100A drives the pressurizing pump 23 to perform seawater system reverse osmosis membrane treatment. The means 20A is activated. The predetermined seawater-based reverse osmosis membrane treatment means start water level is set at a position lower than the predetermined seawater-based reverse osmosis membrane treatment means stop water level.
As a result, the seawater desalination system 1A is in a state where the sewage reverse osmosis membrane treatment means 10A and the seawater reverse osmosis membrane treatment means 20A are driven again, and the sewage permeate W11 and the seawater permeation are stored in the storage tank 41. Water W21 will be supplied.

On the other hand, for example, when the generation amount of the sewage system permeate water W11 (the generation amount of the mixed permeate water W40) is larger than the drainage amount of the mixed permeate water W40, the water level of the mixed permeate water W40 in the storage tank 41 further increases.
When the water level of the mixed permeated water W40 transmitted from the water level gauge 42 reaches a predetermined total reverse osmosis membrane treatment means stop water level, the control means 100A stops the pressurization pump 13 and the pressurization pump 23 to stop the sewage system. The driving of the reverse osmosis membrane processing means 10A and the seawater-based reverse osmosis membrane processing means 20A is stopped. The total reverse osmosis membrane treatment means stop water level is set to a position higher than the predetermined seawater system reverse osmosis membrane treatment means stop water level.
Thereby, the seawater desalination system 1A is in a fully stopped state in which both the sewage reverse osmosis membrane treatment means 10A and the seawater reverse osmosis membrane treatment means 20A are stopped, and can prevent the storage tank 41 from overflowing. In this all-stopped state, the control means 100A determines that when the water level of the mixed permeated water W40 transmitted from the water level gauge 42 falls and reaches a predetermined seawater system reverse osmosis membrane treatment means stop water level, 13 is restarted and the sewage reverse osmosis membrane treatment means 10A is activated.

Further, the control means 100A is configured such that the salinity of the sewage permeate W11 measured by the sewage permeate EC meter 130, the salinity of the seawater permeate W21 measured by the seawater permeate EC meter 230, or the storage tank EC. Control in which the pressurizing pump 23 is stopped and the seawater system reverse osmosis membrane treatment means 20A is stopped when any of the salinity concentrations of the mixed permeated water W40 measured by the total 430 does not satisfy the standard capable of flowing into the supply system. I do.
Accordingly, the seawater desalination system 1A is in a state where only the sewage system reverse osmosis membrane treatment means 10A is driven, and only the sewage system permeated water W11 is supplied to the storage tank 41.

The seawater desalination system 1A of the second embodiment has the following effects.
In the seawater system reverse osmosis membrane treatment means 20A, the mixed water of the sewage system concentrated water W12 and the seawater W20 having a salinity lower than that of the seawater W20 is subjected to membrane separation treatment to generate seawater system permeate W21 that is fresh water. Compared to the case where seawater W20 having a high concentration is subjected to membrane separation treatment to produce fresh water, energy for producing fresh water can be reduced.
Further, the seawater system reverse osmosis membrane treatment means 20A is activated or stopped according to the water level in the storage tank 41 of the mixed permeated water W40 in which the sewage system permeate water W11 and the seawater system permeate water W21, which are fresh water, are mixed. Therefore, for example, when the sewage system permeate W11 is sufficiently generated and a desired amount of water can be secured, the seawater system reverse osmosis membrane treatment means that requires more energy than the sewage system reverse osmosis membrane treatment means 10. 20A can be stopped.
Therefore, it is possible to provide a seawater desalination system that can reduce energy for generating fresh water and can secure a desired amount of water in the generated fresh water.

Further, the seawater system reverse osmosis membrane treatment means 20A starts or stops according to the salinity concentration of the seawater permeate water W21, the salinity concentration of the sewage system permeate water W11, and the salt concentration of the mixed permeate water W40. If any of the salinity concentration of the water-based permeated water W11 and the salt concentration of the mixed permeated water W40 is higher than a predetermined reference value, the seawater-based reverse osmosis membrane treatment means 20A is stopped to produce the mixed permeated water W40 that is the fresh water generated. The salinity of can be returned to the standard.
Therefore, it is possible to provide a seawater desalination system capable of reducing energy for generating fresh water and ensuring water quality in the generated fresh water.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Seawater desalination system 10 Sewage system reverse osmosis membrane treatment means 20 Seawater system reverse osmosis membrane treatment means 100 Control means 230 Seawater system permeate EC meter W10 Sewage W11 Sewage system permeate water W12 Sewage system concentrated water W20 Seawater W21 Seawater system permeate W22 Seawater concentrated water

Claims (13)

Sewage reverse osmosis membrane treatment means for producing sewage permeate and sewage concentrated water by subjecting sewage to membrane separation,
A salinity concentration measuring means for measuring a salinity concentration of the seawater permeate by generating a seawater permeate and a seawater concentrate by subjecting a mixed water of the sewage concentrate and the taken seawater to membrane separation treatment; Seawater-based reverse osmosis membrane treatment means having,
A seawater desalination system, wherein the seawater permeate is supplied to the sewage reverse osmosis membrane treatment means according to the salinity concentration of the seawater permeate. A seawater desalination system having a sewage reverse osmosis membrane treatment means for producing sewage permeate and sewage concentrate by subjecting sewage to membrane separation,
A salinity concentration measuring means for measuring a salinity concentration of the seawater permeate by generating a seawater permeate and a seawater concentrate by subjecting a mixed water of the sewage concentrate and the taken seawater to membrane separation treatment; A seawater-based reverse osmosis membrane treatment means,
Control means for controlling the driving of the sewage reverse osmosis membrane treatment means and the seawater reverse osmosis membrane treatment means according to the salinity concentration of the seawater permeable water,
A seawater desalination system. Further comprising second seawater-based reverse osmosis membrane treatment means for membrane separation treatment of the seawater-based permeated water,
The control means supplies the seawater-based permeated water to the second seawater-based reverse osmosis membrane processing means according to the salinity concentration of the seawater-based permeated water measured by the salinity concentration measuring means. Item 3. A seawater desalination system according to item 2. The control means supplies the seawater permeate to the sewage reverse osmosis membrane treatment means according to the salt concentration of the seawater permeate measured by the salinity measurement means,
The seawater desalination system according to claim 2, wherein the sewage reverse osmosis membrane treatment means performs membrane separation treatment on the mixed water of the seawater permeate and sewage supplied from the seawater reverse osmosis membrane treatment means.   The reverse osmosis membrane provided in the seawater-based reverse osmosis membrane treatment means includes an inflow amount and salinity of sewage flowing into the sewage system reverse osmosis membrane treatment means, an inflow amount of seawater flowing into the seawater-type reverse osmosis membrane treatment means, and The reverse osmosis membrane having a suitable desalination rate, selected based on the salinity concentration, the amount of seawater-based permeated water generated by the seawater-based reverse osmosis membrane treatment means set in advance, and the salinity concentration. The seawater desalination system according to any one of the above. Sewage reverse osmosis membrane treatment means for producing sewage permeate and sewage concentrated water by subjecting sewage to membrane separation,
Seawater-based reverse osmosis membrane treatment means for producing seawater-based permeated water and seawater-based concentrated water by subjecting seawater to membrane separation treatment;
A storage system having a storage tank for storing mixed permeated water in which the sewage system permeated water and the seawater system permeated water are mixed, and a water level meter for measuring the water level of the mixed permeated water stored in the storage tank. ,
The said storage system is a seawater desalination system which starts or stops the said seawater system reverse osmosis membrane process means according to the water level measured with the said water level gauge. The storage system includes first salinity concentration measuring means for measuring the salinity concentration of the mixed permeated water stored in the storage tank,
The sewage reverse osmosis membrane treatment means has a second salinity concentration measuring means for measuring the salinity of the generated sewage permeated water,
The seawater-based reverse osmosis membrane treatment means has a third salinity concentration measuring means for measuring the salinity concentration of the generated seawater-based permeated water, and the salt concentration of the seawater-based permeated water and the salinity concentration of the sewage-based permeated water. And the seawater desalination system of Claim 6 which starts or stops according to the salinity density | concentration of the said mixed permeated water. A sewage reverse osmosis membrane treatment step for producing sewage permeate and sewage concentrate by subjecting sewage to membrane separation;
A seawater-based reverse osmosis membrane treatment step for producing a seawater-based permeated water and a seawater-based concentrated water by subjecting a mixed water of the sewage-based concentrated water and the taken seawater to membrane separation;
A salinity measuring step for measuring the salinity of the seawater permeate;
A seawater desalination method comprising: a seawater permeate circulating step for returning the seawater permeate to the sewage reverse osmosis membrane treatment step according to the salinity concentration of the seawater permeate. A seawater desalination method comprising a sewage reverse osmosis membrane treatment step for producing sewage permeate and sewage concentrate by subjecting sewage to membrane separation,
A seawater-based reverse osmosis membrane treatment step for producing a seawater-based permeated water and a seawater-based concentrated water by subjecting a mixed water of the sewage-based concentrated water and the taken seawater to membrane separation;
A salinity measuring step for measuring the salinity of the seawater permeate;
A seawater desalination method comprising: a sewage reverse osmosis membrane treatment step and a continuation determination step that decides continuation of the seawater reverse osmosis membrane treatment step according to the salinity of the seawater permeate. . Further comprising a second seawater-based reverse osmosis membrane treatment step for membrane separation treatment of the seawater-based permeated water,
The seawater-based permeated water is treated in the second seawater-based reverse osmosis membrane treatment step according to the salt concentration of the seawater-based permeated water measured in the salt concentration measuring step. Seawater desalination method. A seawater-based permeated water circulation step for returning the seawater-based permeated water to the sewage system reverse osmosis membrane treatment step according to the salt concentration of the seawater-based permeated water measured in the salt concentration measuring step,
The seawater desalination method according to claim 9, wherein the sewage reverse osmosis membrane treatment step performs a membrane separation treatment on the mixed water of the seawater permeate and sewage returned in the seawater permeate circulation step. A sewage reverse osmosis membrane treatment step for producing sewage permeate and sewage concentrate by subjecting sewage to membrane separation;
Seawater-based reverse osmosis membrane treatment step for producing seawater-based permeated water and seawater-based concentrated water by subjecting seawater to membrane separation;
A storage step of storing a mixed permeated water in which the sewage permeated water and the seawater-based permeated water are mixed in a storage tank;
A water level measuring step for measuring the level of mixed permeated water stored in the storage tank;
A seawater desalination method comprising: a determination step for determining whether or not to perform the seawater-based reverse osmosis membrane treatment step according to the water level measured in the water level measurement step. A first salinity measurement step for measuring the salinity of the mixed permeated water stored in the storage tank;
A second salinity measurement step for measuring the salinity of the sewage permeated water generated in the sewage reverse osmosis membrane treatment step;
A third salinity concentration measurement step for measuring the salinity concentration of the seawater-based permeated water generated in the seawater-based reverse osmosis membrane treatment step,
The determining step determines whether or not to perform the seawater-based reverse osmosis membrane treatment step according to the salt concentration of the seawater-based permeated water, the salt concentration of the sewage-based permeated water, and the salt concentration of the mixed permeated water. The seawater desalination method according to claim 12.

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