JP6033118B2 - Reverse osmosis membrane device - Google Patents

Description

  The present invention relates to a reverse osmosis membrane device that includes a power recovery device and enables a large volume of permeate production and a low cost of the device.

  For example, a reverse osmosis membrane device including a reverse osmosis membrane module is used to generate fresh water from seawater and clean water from rivers and lakes. The reverse osmosis membrane device performs pretreatment such as taking raw seawater, rivers, lake water, etc., and then performing sterilization by introducing a bactericidal agent, removing impurities with a sand filter, etc. The generated treated water (clear water) is used. The water to be treated is supplied to the reverse osmosis membrane module with a high pressure pump at a high pressure of, for example, about 6.0 MPa, and the reverse osmosis membrane provided in the reverse osmosis membrane module is permeated by reverse osmosis to produce production water. Permeated water is obtained.

  The reverse osmosis membrane module includes a high pressure vessel and a plurality of reverse osmosis membrane elements arranged in series inside the high pressure vessel. The reverse osmosis membrane module has a cylindrical shape and is a spiral membrane in which a bag-like reverse osmosis membrane is wound spirally through a mesh spacer, or a flat membrane in which a plurality of flat sheet-like reverse osmosis membranes are stacked. There is a type of reverse osmosis membrane element. The reverse osmosis membrane module separates water to be treated from the reverse osmosis membrane element in the first stage into permeated water and concentrated water containing salt and impurities in order, and obtains permeated water with each reverse osmosis membrane element. The concentrated water separated from the permeated water is further membrane-separated into permeated water and concentrated water by the reverse osmosis membrane element on the downstream side.

  In a fresh water generator using a reverse osmosis membrane, the power cost (power cost) accounts for about half of the running cost. Therefore, reducing the power cost is an effective cost reduction measure. As a measure for reducing the power cost, it has been conventionally practiced to reduce the amount of electric power by using a power recovery device that recovers the power of the high-pressure pump with high efficiency. Patent Document 1 discloses a reverse osmosis membrane device using such a power recovery device.

  FIG. 6 is a diagram schematically showing the reverse osmosis membrane device disclosed in Patent Document 1. As shown in FIG. In FIG. 6, the reverse osmosis membrane device 100 has a treated water supply path 102 connected to the reverse osmosis membrane module 106, and the treated water supply path 102 supplies the treated water tw to the reverse osmosis membrane module 106 at a high pressure. The high-pressure pump 104 and the drive motor 104a for the high-pressure pump 104 are provided. The treated water tw is separated into permeated water pw and concentrated water cw by a reverse osmosis membrane provided inside the reverse osmosis membrane module 106. The permeated water pw is sent from the permeated water outflow path 108 to the subsequent processing step, and the concentrated water cw is discharged from the concentrated water outflow path 110.

  A detour 112 is branched from the treated water supply path 102 upstream of the high-pressure pump 104, and the detour 112 is joined to the treated water supply path 102 downstream of the high-pressure pump. A power recovery device 114 is interposed in the concentrated water outlet 110 and the bypass 112. The power recovery device 114 is, for example, a positive displacement power recovery device, and includes a high-pressure side inlet 116, a high-pressure side outlet 118, a low-pressure side inlet 120, and a low-pressure side outlet 122. A booster pump 124 and a drive motor 124 a for the booster pump 124 are provided in the bypass 112 on the downstream side of the power recovery device 114. In addition, a flow rate adjustment valve 126 is provided in the concentrated water outflow passage 110 on the downstream side of the power recovery device.

  The concentrated water cw flows from the high-pressure side inlet 116, and the treated water tw flowing from the low-pressure side inlet 120 is boosted using the pressure energy (dynamic pressure) held by the concentrated seawater cs. The treated water tw whose pressure has been increased flows into the booster pump 124 from the high-pressure side outlet 118. The concentrated water cw having exhausted the pressure energy is discharged through the low pressure side outlet 122 and the flow rate adjustment valve 126. The booster pump 124 boosts the water to be treated tw that has flowed out of the power recovery device 114 to a pressure approximately equal to that of the water to be treated tw boosted by the high-pressure pump 104. The treated water tw flowing out of the booster pump 124 merges with the treated water tw flowing through the treated water supply path 102 and is sent to the reverse osmosis membrane module 106.

JP 2011-240234 A

Generally, in the case of a seawater desalination plant, the permeated water recovery rate (permeated water amount / supply water amount) using a reverse osmosis membrane device is about 30 to 50%. For example, when the recovery rate is 40%, the amount of permeated water pw is 1,000 m ³ / h if the amount of water to be treated tw is 2,500 m ³ / h, for example. When the outlet water amount of the high-pressure pump 104 is 1,000 m ³ / h among the supply water amount of the treated water tw, the remaining 1,500 m ³ / h branches from the treated water supply path 102 to the bypass 112, After being boosted by the power recovery device 114, it flows into the booster pump 124. That is, the inlet water amount of the booster pump 124 is 1,500 m ³ / h.

In general, the maximum capacity of the high-pressure pump is about 3,000 m ³ / h, whereas the maximum capacity of the booster pump is about 2,000 m ³ / h, which is smaller than that of the high-pressure pump. Therefore, when it is desired to increase the permeated water production amount of the reverse osmosis membrane device, there is a restriction due to the capacity of the booster pump. For example, a description will be given with a recovery rate of 40% as described above. If the amount of water to be treated tw is 5,000 m ³ / h, the amount of permeated water pw is 2,000 m ³ / h. Of the supply water amount of the treated water tw, when the outlet water amount of the high-pressure pump 104 is 2,000 m ³ / h, the remaining 3,000 m ³ / h branches from the treated water supply path 102 to the detour 112. After being boosted by the power recovery device 114, it flows into the booster pump 124.

As mentioned above, since the maximum capacity of the booster pump is about 2,000 m ³ / h, it can be handled by installing two booster pumps 124 in parallel. However, since the two booster pumps 124 are installed in parallel, there is a possibility that an uneven flow occurs between the booster pumps 124 and the flow rate control becomes difficult. In addition, it is necessary to increase the booster pump 124, resulting in high cost.

  Furthermore, the booster pump is usually controlled in flow rate (rotational speed control) by VFD control, but there is a problem that the control range of the rotational speed is large and the pump efficiency and the motor efficiency are low at low loads. Moreover, when seawater is seawater, since corrosion resistance is requested | required, it is necessary to use high-grade materials, such as a duplex stainless steel, and an initial cost becomes large. In addition, the seal part of the sliding part is easily corroded by salt contained in seawater, and the high-pressure treated water that flows out of the power recovery device flows in. Therefore, the seal part needs to have a special structure, and the cost is high. There is a problem of becoming.

  An object of the present invention is to make it possible to increase the volume of permeated water produced and to reduce the cost of the device in a reverse osmosis membrane device having a power recovery device in view of the problems of the prior art.

  In order to achieve such an object, the reverse osmosis membrane device of the present invention branches from the treated water supply path upstream of the high pressure pump, and supplies the treated water downstream of the high pressure pump and upstream of the reverse osmosis membrane module. A power recovery device that increases the pressure of water to be treated flowing through the detour by the dynamic pressure of the concentrated water discharged to the concentrated water outflow path, Provided at the junction between the treated water supply path and the detour, the treated water flowing through the detour using the treated water flowing through the treated water supply path on the downstream side of the high-pressure pump as a driving fluid is sucked and treated water An ejector pump that mixes the water to be treated flowing through the supply path and the water to be treated flowing from the detour and sends it to the reverse osmosis membrane module; and pressure control means for controlling the pressure of the water to be treated flowing into the reverse osmosis membrane module; It has.

In the present invention, the conventional problem is solved by providing an ejector pump at the junction of the treated water supply path and the bypass. In other words, this ejector pump sucks the treated water in the detour using the high-pressure treated water discharged from the high-pressure pump as the driving fluid, and mixes both, so that no new power is required and the treated water in the detour is treated. Can increase water pressure.
Moreover, the capacity of the ejector pump is not strict as the booster pump, and the capacity can be increased. Further, since there is no seal portion, non-rectification is unlikely to occur, and it is not necessary to have a special seal structure, so that the cost can be reduced.

  In order to obtain the target water quality of the permeated water, a method of changing the recovery rate of the reverse osmosis membrane module is effective. However, in this case, the amount of permeated water may fluctuate, and stable supply of permeated water may not be possible. Therefore, as a method of increasing the amount of permeated water, there is a method of increasing the supply pressure of water to be treated to the reverse osmosis membrane element. In the present invention, the pressure control means for controlling the pressure of the water to be treated flowing into the reverse osmosis membrane module is provided, and by controlling the pressure of the water to be treated flowing into the reverse osmosis membrane module by the pressure control means, Stable supply of permeated water with quality that meets the required value.

  As one aspect of the present invention, the pressure control means can be a pressure control valve provided in the water to be treated supply path between the ejector section and the reverse osmosis membrane module. Thereby, the configuration of the pressure control means can be simplified and reduced in cost.

  As another aspect of the present invention, the pressure control means is provided in an ejector pump, and moves in the axial direction of the nozzle portion to the nozzle portion to which the treated water flowing from the treated water supply path downstream of the high-pressure pump is jetted. Thus, the slide valve body that can change the flow path area of the nozzle portion and the actuator that moves the slide valve body in the axial direction of the nozzle portion can be used. By moving the slide valve body in the axial direction of the nozzle portion, the flow path cross-sectional area formed in the nozzle portion can be made variable. Therefore, the pressure control of the water to be treated flowing into the reverse osmosis membrane module can be accurately performed.

  As one aspect of the present invention, a reverse side osmosis is provided in the treated water supply path on the inlet side of the reverse osmosis membrane module, the thermometer for detecting the temperature of the treated water, and the outlet side of the reverse osmosis membrane module. A salt concentration meter for detecting the salt concentration of the permeated water flowing out from the membrane module and a control device for controlling the pressure of the water to be treated flowing into the reverse osmosis membrane module can be provided. The control device receives the detected values of the thermometer and the salt concentration meter, and controls the pressure of the water to be treated flowing into the reverse osmosis membrane module based on the detected values.

  The quality of the permeated water may deteriorate due to aging of the osmotic membrane or increase in seawater temperature, and may not satisfy the target value. In addition, the quality of the permeate varies depending on the quality of the raw seawater (such as salt concentration). In the above aspect of the present invention, the control device controls the pressure of the water to be treated at the inlet of the reverse osmosis membrane module while monitoring the temperature of the water to be treated and the salt concentration of the permeated water. Stable supply of permeated water is possible while satisfying the value.

  As one aspect of the present invention, the treated water supply path on the high-pressure pump outlet side branches into a plurality of branched supply paths, and branches from the treated water supply path on the high-pressure pump inlet side into the same number of branch detours as the branched supply paths The number of branch supply paths and the number of branch detours are the same, and a plurality of pairs are formed so that one branch supply path and one branch detour correspond to each other. For each set, a reverse osmosis membrane module, a concentrated water outflow passage, a detour, a power recovery device, an ejector pump, and a pressure control means can be provided. In this aspect, since the permeate production line is divided into groups, the operation control of each group is facilitated, and even if one group is stopped for maintenance, the other group can be operated. You can continue. Further, since only one high-pressure pump is required as a driving source, there is an advantage that the power cost of the entire apparatus does not increase.

  According to the present invention, since the pressure of the water to be treated that has flowed out of the power recovery apparatus is increased by the ejector pump, it is possible to realize a large volume of permeate production and a low cost of the reverse osmosis membrane apparatus. Further, it is possible to stably supply permeated water having a quality that satisfies the required value.

1 is a system diagram of a reverse osmosis membrane device according to a first embodiment of the present invention. It is a front view sectional view of the ejector pump used in the 1st embodiment. It is a systematic diagram of the reverse osmosis membrane apparatus which concerns on 2nd Embodiment of this invention. It is a systematic diagram of the reverse osmosis membrane apparatus which concerns on 3rd Embodiment of this invention. It is front view sectional drawing of the ejector pump used in the said 3rd Embodiment. It is a systematic diagram of the conventional reverse osmosis membrane apparatus.

  Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this embodiment are not intended to limit the scope of the present invention to that unless otherwise specified.

(Embodiment 1)
1st Embodiment of this invention is described based on FIG.1 and FIG.2. This embodiment is an example of a reverse osmosis membrane device applied to seawater desalination treatment. In the reverse osmosis membrane device 10A shown in FIG. 1, as a pretreatment, the clear seawater sw, which is treated water from which raw seawater has been sterilized and relatively large impurities such as garbage and microorganisms have been removed, is used as a reverse osmosis membrane module. A to-be-treated water supply path 12 for supplying to 16 is provided. The treated water supply path 12 is provided with a high-pressure pump 14, and the clear seawater sw is supplied to the reverse osmosis membrane module 16 at a high pressure by the high-pressure pump 14. The reverse osmosis membrane module 16 has a built-in reverse osmosis membrane, and the clear seawater sw is separated into permeated water pw and concentrated seawater cs by the reverse osmosis membrane.

  The permeated water pw is sent from the permeated water outflow path 18 to the subsequent processing step, and the concentrated seawater cs is discharged to the concentrated seawater outflow path 20. A bypass 22 is branched from the treated water supply path 12 on the upstream side of the high-pressure pump 14. The bypass 22 joins the treated water supply path 12 on the downstream side of the high-pressure pump 14, and an ejector pump 26 is provided at the junction between the bypass 22 and the treated water supply path 12. A pressure exchange type power recovery device 24 is interposed in the detour 22 and the concentrated seawater outflow passage 20.

The power recovery device 24 is a pressure exchange type power recovery device that exchanges pressure between the high-pressure concentrated seawater cs discharged to the concentrated seawater outflow passage 20 and the low-pressure clear seawater sw flowing from the bypass 22. The power recovery device 24 is conventionally known (see, for example, Japanese Patent Application Laid-Open No. 2011-56439).
A pressure control valve 28 is provided in the treated water supply path 12 between the ejector pump 26 and the reverse osmosis membrane module 16, and a flow rate adjustment valve 30 is provided in the concentrated seawater outflow path 20 on the downstream side of the power recovery device 24. Yes.

  A pressure gauge 32 and a thermometer 34 are provided in the treated water supply path 12 between the pressure control valve 28 and the reverse osmosis membrane module 16, and the electric conductivity of the permeated water pw is detected in the permeated water outflow path 18. A salt concentration meter 36 for obtaining the salt concentration from the detected value is provided. The detection values of the pressure gauge 32, the thermometer 34, and the salt concentration meter 36 are input to the control device 38. The control device 38 controls the operation of the drive motor 14a of the high-pressure pump 14 based on these detection values, and The opening degree of the pressure control valve 28 and the flow rate adjustment valve 30 is controlled.

  The concentrated seawater cs discharged at a high pressure from the reverse osmosis membrane module 16 to the concentrated seawater outflow passage 20 is boosted in the power recovery device 24 by the pressure energy (dynamic pressure) held by the clear seawater sw flowing through the detour 22. Let The clear seawater sw whose pressure is increased and the flow velocity is increased reaches the ejector pump 26. Hereinafter, the configuration of the ejector pump 26 will be described with reference to FIG.

  In FIG. 2, the ejector pump 26 includes a hollow casing 40, and the casing 40 forms a diffusion chamber 42, an equal-diameter mixing portion 44, and a diffuser portion 46 whose diameter gradually increases. The diffusion chamber 42 incorporates a nozzle 48 located on the central axis. The clear seawater sw flowing through the treated water supply path 12 flows into the nozzle 48 at a high pressure from the direction of arrow a, and is jetted from the nozzle port 48a of the nozzle 48. The jetted clear seawater sw serves as a driving fluid, and the inside of the diffusion chamber 42 is in a vacuum state, so the clear seawater sw that flows through the detour 22 is sucked in the direction of the arrow b. These two flows are mixed in the mixing unit 44, and the speed is increased and the pressure is reduced. Next, the diffuser 46 decelerates and the pressure rises.

  The pressure of the mixed flow of the clear seawater sw whose pressure has been increased in this way is adjusted by the pressure control valve 28 and flows into the reverse osmosis membrane module 16. The control device 38 monitors the pressure and temperature of the clear seawater sw flowing into the reverse osmosis membrane module 16 with the pressure gauge 32 and the thermometer 34, and monitors the salt concentration of the permeated water pw with the salt concentration meter 36. And based on these detected values, by controlling the opening degree of the pressure control valve 28 and the flow rate adjusting valve 30, the permeate recovery rate of the reverse osmosis membrane module 16 is controlled, and the water quality of the permeate pw is the required value. And the permeate production volume is maintained at the target value.

According to the present embodiment, by providing the ejector pump 26 at the junction of the treated water supply path 12 and the bypass 22, it is possible to increase the pressure of the clear seawater sw in the bypass 22 without requiring new power. .
Further, the ejector pump 26 does not have a strict capacity limit unlike the booster pump, can be increased in capacity, and has no seal portion. Therefore, non-rectification is unlikely to occur, and it is not necessary to have a special seal structure. Therefore, cost reduction is possible.

Moreover, since the pressure control valve 28 is provided and the opening degree of the pressure control valve 28 is controlled by the control device 38, the quality of the permeated water pw satisfying the required value can be obtained, and the permeated water production amount can be stabilized. While being able to supply, the structure of a pressure control means can be simplified and cost-reduced.
Further, a thermometer 34 and a salt concentration meter 36 are provided, and the control device 38 controls the pressure of the clarified seawater sw flowing into the reverse osmosis membrane module 16 according to the temperature and salt concentration of the clarified seawater sw. The water quality of the water pw can satisfy the required value, and a stable supply of permeate production can be achieved.

  In the present embodiment, the high-pressure pump 14, the pressure control valve 28, and the flow rate adjustment valve 30 are automatically controlled by the control device 38, but instead, the operator may manually operate them.

(Embodiment 2)
Next, a second embodiment of the present invention will be described with reference to FIG. In the reverse osmosis membrane device 10B of the present embodiment, the detour 22 branched from the treated water supply path 12 on the upstream side of the high-pressure pump 14 is branched into branch detours 22a and 22b, and the treated water supply path 12 is also high-pressure. It branches into the branch supply paths 12a and 12b on the downstream side of the pump.

  From the upstream side, the branch supply path 12a is provided with an ejector pump 26a, a pressure control valve 28a, and a reverse osmosis membrane module 16a. The reverse osmosis membrane module 16a is provided with a permeate outflow path 18a and a concentrated seawater outflow path 20a. Yes. A power recovery device 24a is interposed in the concentrated seawater outflow path 20a and the branch bypass circuit 22a. A salt concentration meter 36a is provided in the permeate outflow passage 18a, and a flow rate adjusting valve 30a is provided in the concentrated seawater outflow passage 20a on the downstream side of the power recovery device 24a.

  From the upstream side, the branch supply path 12b is provided with an ejector pump 26b, a pressure control valve 28b, and a reverse osmosis membrane module 16b. The reverse osmosis membrane module 16b is provided with a permeate outflow path 18b and a concentrated seawater outflow path 20b. Yes. A power recovery device 24b is interposed in the concentrated seawater outflow path 20b and the branch bypass circuit 22b. A salt concentration meter 36b is provided in the permeate outflow passage 18b, and a flow rate adjusting valve 30b is provided in the concentrated seawater outflow passage 20b on the downstream side of the power recovery device 24b.

  The power recovery devices 24a and 24b have the same configuration as that of the pressure exchange type power recovery device 24 used in the first embodiment. The operation of each group in the branch supply paths 12a, 12b and the branch detours 22a, 22b is controlled by the control device 38, and the operation in each group performs the same operation as in the first embodiment. That is, it operates simultaneously in each group, and the permeated water pw can be manufactured simultaneously with the reverse osmosis membrane modules 16a and 16b.

  According to this embodiment, since the permeate production line is divided for each group, the operation control of each group is facilitated, and even if one group stops operation for maintenance and inspection, You can continue driving. Further, since only one high-pressure pump 14 is required as a drive source, there is an advantage that the power cost of the entire apparatus does not increase.

(Embodiment 3)
Next, a third embodiment of the present invention will be described with reference to FIGS. In the reverse osmosis membrane device 10 </ b> C of the present embodiment, a variable flow rate ejector pump 50 is provided in the treated water supply path 12. By using a variable flow rate ejector pump, the pressure control valve 28 is not required. Other configurations are the same as those of the first embodiment. Hereinafter, the configuration of the ejector pump 50 will be described with reference to FIG.

  In FIG. 5, a conical slide valve body 52 having a pointed tip on the axis of the nozzle 48 is provided inside the nozzle 48. A rack 54 is coupled to the root portion of the slide valve body 52. Further, a pinion 58 that meshes with the rack 54 is provided, and the pinion 58 is closely fitted to the output shaft 56 a of the motor 56. By driving the motor 56, the slide valve body 52 moves in the arrow d direction. The operation of the motor 56 is controlled by the control device 38. The other structure of the ejector pump 50 is the same as the structure of the ejector pump 26 shown in FIG.

  In the present embodiment, the flow rate of the clear seawater sw in the treated water supply path 12 can be controlled by moving the slide valve body 52 in the arrow d direction. Thereby, the pressure of the clear seawater sw flowing into the reverse osmosis membrane module 16 can be controlled. By such a control means, the pressure control of the clear seawater sw flowing into the reverse osmosis membrane module 16 can be accurately performed.

  According to the present invention, in a reverse osmosis membrane device having a power recovery device, it is possible to realize a large volume of permeated water production and cost reduction of the device.

10A, 10B, 10C, 100 Reverse osmosis membrane device 12,102 Water supply path to be treated 12a, 12b Branch supply path 14,104 High pressure pump 14a, 104a Drive motor 16, 16a, 16b, 106 Reverse osmosis membrane module 18, 18a, 18b, 108 Permeate outflow path 20, 20a, 20b, 110 Concentrated seawater outflow path 22, 112 detour 22a, 22b Branch detour 24, 24a, 24b Power recovery device 26, 26a, 26b, 50 Ejector pump 40 Casing 42 Diffusion chamber 44 Mixing unit 46 Diffuser unit 48 Nozzle 48a Nozzle port 52 Slide valve element 54 Rack 56 Motor 56a Output shaft 58 Pinion 28, 28a, 28b Pressure control valve 30, 30a, 30b, 126 Flow rate adjusting valve 32, 32a, 32b Pressure gauge 34 , 34a, 34 b Thermometer 36, 36a, 36b Salt concentration meter 38 Control device 114 Power recovery device 116 High pressure side inlet 118 High pressure side outlet 120 Low pressure side inlet 122 Low pressure side outlet 124 Booster pump 124a Drive motor cs Concentrated seawater cw Concentrated water pw Permeated water sw Kiyosumi Seawater tw Water to be treated

Claims (5)

A reverse osmosis membrane module, and a reverse osmosis membrane module that separates treated water into permeate and concentrated water;
A high-pressure pump for supplying the treated water at a high pressure to the reverse osmosis membrane module;
A treated water supply path for supplying the treated water to the high-pressure pump;
In a reverse osmosis membrane device comprising a concentrated water outflow passage for discharging the concentrated water from the reverse osmosis membrane module,
A detour that branches from the treated water supply path upstream of the high-pressure pump, and merges with the treated water supply path downstream of the high-pressure pump and upstream of the reverse osmosis membrane module;
A power recovery device that intervenes in the concentrated water outflow path and the detour, and increases the pressure of the treated water flowing through the detour by the dynamic pressure of the concentrated water discharged to the concentrated water outflow path;
The treated water that is provided at a junction of the treated water supply path and the bypass and flows from the bypass as the driving fluid using the treated water flowing through the treated water supply path downstream of the high-pressure pump. An ejector pump that sucks water, mixes the treated water flowing through the treated water supply path and the treated water flowing from the bypass, and sends the mixed water to the reverse osmosis membrane module;
A reverse osmosis membrane device comprising pressure control means for controlling the pressure of the water to be treated flowing into the reverse osmosis membrane module. The pressure control means includes
The reverse osmosis membrane device according to claim 1, wherein the reverse osmosis membrane device is a pressure control valve provided in the treated water supply path between the ejector pump and the reverse osmosis membrane module. The pressure control means includes
The nozzle portion is provided in the ejector pump and moves in the axial direction of the nozzle portion to the nozzle portion from which the water to be treated flowing from the treatment water supply passage on the downstream side of the high-pressure pump is jetted. A slide valve body having a variable area;
The reverse osmosis membrane device according to claim 1, comprising an actuator that moves the slide valve body in an axial direction of the nozzle portion. A thermometer that is provided in the treated water supply path on the inlet side of the reverse osmosis membrane module and detects the temperature of the treated water;
A salt concentration meter that is provided on the outlet side of the reverse osmosis membrane module and detects the salt concentration of the permeated water flowing out of the reverse osmosis membrane module;
A controller for controlling the pressure of the treated water flowing into the reverse osmosis membrane module,
The control device receives detection values of the thermometer and the salt concentration meter, and controls the pressure of the water to be treated flowing into the reverse osmosis membrane module based on the detection values. Item 4. The reverse osmosis membrane device according to any one of Items 1 to 3. The treated water supply path on the outlet side of the high-pressure pump branches into a plurality of branch supply paths, and branches from the treated water supply path on the inlet side of the high-pressure pump into a plurality of branch detours,
The plurality of branch supply paths and the plurality of branch bypass paths are the same number, and a plurality of sets are formed so that one branch supply path and one branch bypass path correspond to each other,
The reverse osmosis membrane module, the concentrated water outflow passage, the power recovery device, the ejector pump, and the pressure control means are provided for each set of the branch supply passage and the branch bypass route. The reverse osmosis membrane device according to claim 1.

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