TW202302472A - Water treatment method and water treatment device - Google Patents

Abstract

An object of the invention is to enable stable processing when using a semipermeable membrane module to concentrate water, even when there is variation in the water quality. The water treatment method of the invention includes: a pressurization step of pressurizing a water to be treated containing a fully dissolved solid component to a pressure of at least 0.1 MPa; a first reverse osmosis membrane processing step of passing the pressurized water to be treated through a first reverse osmosis membrane to obtain a first RO permeate and a first RO concentrate; a semipermeable membrane processing step, using a semipermeable membrane module having a first space (11) and a second space (13) separated by a semipermeable membrane (15), of flowing the first RO concentrate through the first space (11) and pressurizing the first space (11) by means of the pressure generated in the pressurization step such that the water contained in the first RO concentrate permeates the semipermeable membrane (15) to obtain a concentrate, and flowing a portion of the first RO concentrate or at least a portion of the concentrate into the second space (13) to obtain a diluted water; and a flow rate adjustment step of measuring the flow rate of the concentrate and the flow rate of the diluted water, and adjusting the flow rates such that the measured flow rate of the concentrate and the measured flow rate of the diluted water achieve predetermined target flow rates.

Description

Water treatment method and water treatment device

The present invention relates to a water treatment method and a water treatment device for performing concentration treatment of water including Total Dissolved Solids (TDS) and the like.

In recent years, the amount of discharge water discharged from factories, etc. has been reduced as much as possible, and the discharge water has been concentrated using reverse osmosis membranes, etc., and the method of recovering permeated water to reduce the volume of the discharge water has been adopted. The water recovery rate tends to be as high as possible. Among them, the number of factories implementing ZLD (Zero Liquid Discharge) is also increasing. They use methods such as evaporation and concentration to recover almost the total amount of water to make the total dissolved Solids and the like are solidified and discharged.

Methods of heating water such as evaporative concentration require huge energy consumption and increase costs. Therefore, it is required to concentrate the discharged water at a high concentration by using a method that does not use heating as much as possible. The reverse osmosis membrane method consumes less energy than the evaporative concentration method, but due to the influence of osmotic pressure, there may be cases where the concentration is insufficient and the volume cannot be reduced to the target water volume.

A method is described in Patent Document 1. The raw water or its concentrated water is circulated to the first space and the second space separated by the semi-permeable membrane of the multi-stage semi-permeable membrane module, and the first space is pressurized to concentrate the water. . The method of Patent Document 1, by reducing the concentration difference (osmotic pressure difference) between the first space and the second space of the semi-permeable membrane module, compared with the concentration method carried out by the general reverse osmosis membrane, can Less pressurization power, ie less energy, concentrates to a high concentration.

The concentration method described in Patent Document 1 requires not only the first space of the semi-permeable membrane module, but also the flow and concentration of the second space to be controlled. Therefore, compared with the reverse osmosis membrane method, it is easy to be affected by the water quality of the raw water (water to be treated). The water balance will become unbalanced due to fluctuations, and it may be difficult to perform volume reduction of the discharge water volume stably. In addition, when such a method of concentrating to a high concentration is used, the water quality of the recovered water may deteriorate and may become unsuitable for recovery. [Prior art literature] [Patent Document]

Patent Document 1: Japanese Patent Laid-Open No. 2018-069198

[Problem to be solved by the present invention]

The purpose of the present invention is to provide a water treatment method and a water treatment device, which can perform stable treatment even when the water quality of the treated water (raw water) changes in the concentration treatment of water using a semi-permeable membrane module . [Technical means to solve the problem]

The water treatment method of the present invention includes the following steps: a pressurization step, pressurizing the treated water containing total dissolved solids to above 0.1 MPa; the first reverse osmosis membrane treatment step, making the pressurized treated water go to The first reverse osmosis membrane circulates to obtain the first RO permeated water and the first RO concentrated water; the semi-permeable membrane treatment step uses a semi-permeable membrane module with a first space and a second space separated by a semi-permeable membrane to make the first RO permeate water and the first RO concentrated water 1RO concentrated water circulates into the first space, pressurizes the first space by the pressurization step, makes the water contained in the 1st RO concentrated water pass through the semi-permeable membrane to obtain concentrated water, and makes the A part of the first RO concentrated water or at least a part of the concentrated water is circulated to the second space to obtain dilution water; and a flow rate adjustment step is to measure the flow rate of the concentrated water and the flow rate of the dilution water, and adjust the flow rate of the concentrated water The measured value and the measured value of the flow rate of the dilution water become a preset target flow rate value.

The water treatment method of the present invention includes the following steps: a pressurization step, pressurizing the treated water containing total dissolved solids to above 0.1 MPa; the first reverse osmosis membrane treatment step, making the pressurized treated water go to The first reverse osmosis membrane circulates to obtain the first RO permeate water and the first RO concentrated water; the semi-permeable membrane treatment step uses a semi-permeable membrane module connected in multiple stages with a first space and a second space separated by a semi-permeable membrane group, the first RO concentrated water is circulated to the first space of the first semi-permeable membrane module, and the first space is pressurized by the pressurization step to make the water contained in the first RO concentrated water Concentrated water is obtained through the semi-permeable membrane, and the concentrated water is further used in the semi-permeable membrane module of the next stage to obtain concentrated water, and a part of the first RO permeated water or at least a part of the concentrated water or other semi-permeable At least a part of the dilution water obtained by the membrane module is circulated to the second space of the semi-permeable membrane module of each section to obtain the dilution water; and the flow rate adjustment step is to measure the flow rate of the concentrated water and the flow rate of the dilution water, and adjust the The measured value of the flow rate of the concentrated water and the measured value of the flow rate of the diluted water become a preset target flow value.

In the above water treatment method, the first reverse osmosis membrane should have a permeation flux of pure water in the range of 0.2-0.7m ³ /m ² /day under the conditions of effective pressure on the membrane surface of 1MPa and 25°C, and have a standard The NaCl removal rate under operating pressure (under the condition of NaCl 32,000mg/L) is more than 99.5%.

In the above water treatment method, the permeation flux of the semipermeable membrane module in the semipermeable membrane treatment step should be 0.005m/d～0.05m/d under the conditions of effective pressure on the membrane surface of 1MPa and 25°C range.

In the above water treatment method, the pressure of the first RO concentrated water immediately after the first reverse osmosis membrane treatment step is above 7MPa; the water treatment method preferably further includes a decompression step: in the front section of the semipermeable membrane treatment step , The 1st RO concentrated water was depressurized to less than 7 MPa.

In the above water treatment method, it is preferable to further include a second reverse osmosis membrane treatment step: allowing the dilution water to flow through the second reverse osmosis membrane to obtain the dilution water of the second RO permeate water and the second RO concentrated water.

In the above water treatment method, it is preferable to further include a third reverse osmosis membrane treatment step: making at least one of the first RO permeate water and the second RO permeate water flow to the third reverse osmosis membrane to obtain the third RO permeate water and the third RO permeate water. Concentrate water.

In the above water treatment method, the first RO concentrated water preferably has a sulfate ion concentration of 20,000 mg/L or more, and at least one of sodium ions and ammonium ions at a concentration of 10,000 mg/L or more.

The water treatment device of the present invention is equipped with: pressurization means, which pressurizes the water to be treated including total dissolved solids to above 0.1 MPa; the first reverse osmosis membrane treatment means, which makes the pressurized water to be treated go to the first The reverse osmosis membrane is circulated to obtain the first RO permeate water and the first RO concentrated water; the semi-permeable membrane treatment means uses a semi-permeable membrane module with a first space and a second space separated by a semi-permeable membrane to concentrate the first RO Water flows into the first space, and the first space is pressurized by the pressurization means, so that the water contained in the first RO concentrated water passes through the semipermeable membrane to obtain concentrated water, and the A part of the first RO concentrated water or at least a part of the concentrated water circulates into the second space to obtain dilution water; and a flow rate adjustment means measures the flow rate of the concentrated water and the flow rate of the diluted water, and adjusts the flow rate of the concentrated water The measured value and the measured value of the flow rate of the dilution water become a preset target flow rate value.

The water treatment device of the present invention is equipped with: pressurization means, which pressurizes the water to be treated including total dissolved solids to above 0.1 MPa; the first reverse osmosis membrane treatment means, which makes the pressurized water to be treated go to the first Reverse osmosis membrane circulates to obtain the first RO permeated water and the first RO concentrated water; the semi-permeable membrane treatment method uses a semi-permeable membrane module connected in multiple sections with a first space and a second space separated by a semi-permeable membrane, The first RO concentrated water is circulated to the first space of the first-stage semi-permeable membrane module, and the first space is pressurized by the pressurization means, so that the water contained in the first RO concentrated water Concentrated water is obtained through the semi-permeable membrane, and the concentrated water is further used in the semi-permeable membrane module of the next stage to obtain concentrated water, and a part of the first RO permeated water or at least a part of the concentrated water or other semi-permeable At least a part of the dilution water obtained by the membrane module circulates to the second space of the semi-permeable membrane module of each section to obtain the dilution water; and the flow adjustment means measures the flow rate of the concentrated water and the flow rate of the dilution water, and adjusts the The measured value of the flow rate of the concentrated water and the measured value of the flow rate of the diluted water become a preset target flow value.

In the above-mentioned water treatment device, the first reverse osmosis membrane should have a pure water permeation flux in the range of 0.2-0.7m ³ /m ² /day under the conditions of effective pressure on the membrane surface of 1 MPa and 25°C, and have standard operation The NaCl removal rate under pressure (under the condition of NaCl 32,000mg/L) is more than 99.5%.

In the above-mentioned water treatment device, it is preferable to further have a permeation flux adjustment means, which adjusts the permeation flux of the semi-permeable membrane module in the semi-permeable membrane treatment means to become The range of 0.005m/d～0.05m/d.

In the above-mentioned water treatment device, the pressure of the first RO concentrated water immediately after the first reverse osmosis membrane treatment means is above 7MPa; the water treatment device should further have a decompression means: in the front section of the semi-permeable membrane treatment means, This 1st RO concentrated water was depressurized to less than 7 MPa.

In the above-mentioned water treatment device, it is preferable to further include a second reverse osmosis membrane treatment means for passing the diluted water to the second reverse osmosis membrane to obtain the second RO permeate water and the second RO concentrated water.

In the above water treatment device, it is preferable to further include a third reverse osmosis membrane treatment means: at least one of the first RO permeated water and the second RO permeated water is circulated to the third reverse osmosis membrane to obtain the third RO permeated water and the third RO concentrated water. water.

In the above water treatment device, the first RO concentrated water preferably has a sulfate ion concentration of 20,000 mg/L or more and at least one of sodium ions and ammonium ions at a concentration of 10,000 mg/L or more. [Effects of the present invention]

According to the present invention, it is possible to provide a water treatment method and a water treatment device that can perform stable treatment even when the water quality of the water to be treated (raw water) fluctuates in the concentration treatment of water using a semipermeable membrane module .

Embodiments of the present invention will be described below. This embodiment is an example of implementing the present invention, and the present invention is not limited to this embodiment.

The outline of an example of the water treatment apparatus which concerns on embodiment of this invention is shown in FIG. 1, and the structure is demonstrated.

The water treatment device 1 shown in FIG. 1 is provided with: a booster pump 26, which is used as a pressurization means to pressurize the treated water containing Total Dissolved Solids (TDS) to 0.1 MPa or more; the first reverse osmosis The membrane treatment device 100, as the first reverse osmosis membrane treatment means, makes the pressurized water to be treated flow to the first reverse osmosis membrane to obtain the first RO permeate water and the first RO concentrated water; and for example, the first stage membrane module unit 12. The second section membrane module unit 14, the third section membrane module unit 16, the fourth section membrane module unit 18, and the fifth section membrane module unit 20, as the semipermeable membrane treatment means, utilize the semipermeable The single-stage or multi-stage semi-permeable membrane module of the first space (concentration side) and the second space (permeation side) separated by the membrane allows the first RO concentrated water to flow into the first space, and is pumped by the booster pump 26 The pressurization carried out pressurizes the first space, makes the water contained in the first RO concentrated water pass through the semipermeable membrane to obtain concentrated water, and makes a part of the first RO concentrated water or at least a part of the concentrated water flow into the second space to obtain dilute with water. The water treatment device 1 is equipped with a pressure pump as a pressurization means for pressurizing the water to be treated including the total dissolved solids to 0.1 MPa or higher only in the front stage of the first reverse osmosis membrane treatment device 100 .

The first membrane module unit 12, for example, has 6 membrane modules connected in parallel; the second membrane module unit 14, for example, has 5 membrane modules connected in parallel; the third membrane module unit 16 , for example, with 4 membrane modules connected in parallel; the 4th membrane module unit 18, for example, with 3 membrane modules connected in parallel; the 5th membrane module unit 20, for example, with 3 membrane modules connected in parallel Membrane module. Each membrane module has a first space 11 and a second space 13 separated by a semipermeable membrane 15 . The water treatment device 1 may also have: a treated water tank 10, which stores the treated water; a concentrated water tank 22, which stores the concentrated water from the final stage membrane module unit (the example of Fig. 1 is from the 5th stage membrane module unit 20 Concentrated water); and the first dilution water tank 24, which stores the dilution water from the first stage membrane module unit (the example in FIG. 1 is the dilution water from the first stage membrane module unit 12).

In the water treatment device 1 of FIG. 1 , a pipe 38 is connected to the water-to-be-treated inlet of the water-to-be-treated tank 10 . The outlet of the water tank 10 to be treated and the inlet of the first reverse osmosis membrane treatment device 100 are connected by a pipe 40 via a pressure pump 26 . The concentrated water outlet of the first reverse osmosis membrane treatment device 100 is connected in parallel with the first space inlet of each membrane module of the first-stage membrane module unit 12 through the first RO concentrated water pipe 106 . The first RO permeate water pipe 108 is connected to the permeate water outlet of the first reverse osmosis membrane treatment device 100 . The first space outlet of each membrane module of the first-stage membrane module unit 12 and the first space inlet of each membrane module of the second-stage membrane module unit 14 are connected in parallel by piping 42 . The outlets of the first spaces of the membrane modules of the second-stage membrane module unit 14 and the inlets of the first spaces of the membrane modules of the third-stage membrane module unit 16 are connected in parallel by pipes 44 . The first space outlet of each membrane module of the third-stage membrane module unit 16 and the first space inlet of each membrane module of the fourth-stage membrane module unit 18 are connected in parallel by piping 46 . The first space outlet of each membrane module of the fourth stage membrane module unit 18 and the first space inlet and the second space inlet of each membrane module of the fifth stage membrane module unit 20 are connected in parallel by piping 48 . The outlet of the first space of each membrane module of the fifth-stage membrane module unit 20 and the inlet of the concentrated water tank 22 are connected by a pipe 50 through a valve 32 . A pipe 52 is connected to the outlet of the concentrated water tank 22 via the pump 28 . The outlet of the second space of each membrane module of the fifth-stage membrane module unit 20 and the inlet of the second space of each membrane module of the fourth-stage membrane module unit 18 are connected in parallel by piping 54 . The outlet of the second space of each membrane module of the fourth-stage membrane module unit 18 and the inlet of the second space of each membrane module of the third-stage membrane module unit 16 are connected in parallel through the pipe 56 . The outlets of the second spaces of the membrane modules of the third-stage membrane module unit 16 and the inlets of the second spaces of the membrane modules of the second-stage membrane module unit 14 are connected in parallel by pipes 58 . The outlets of the second spaces of the membrane modules of the second-stage membrane module unit 14 and the inlets of the second spaces of the membrane modules of the first-stage membrane module unit 12 are connected in parallel through pipes 60 . The outlet of the second space of each membrane module of the first-stage membrane module unit 12 and the inlet of the first dilution water tank 24 are connected by a pipe 62 . A pipe 64 is connected to the outlet of the first dilution water tank 24 . In addition, the water treatment apparatus 1 may or may not include the concentrated water tank 22, the pump 28, and the piping 52. The water treatment device 1 may or may not include the first dilution water tank 24 and the piping 64 .

The pressurizing pump 26 is arranged at the front stage of the first reverse osmosis membrane treatment device 100, for example, is driven at a rotational speed corresponding to the input drive frequency, sucks the water to be treated and sprays it toward the first reverse osmosis membrane treatment device 100 booster pump. The pressure pump 26 is provided with, for example, a first inverter 30 that outputs a driving frequency corresponding to an input command signal to the pressure pump 26 . Between the valve 32 of the piping 50 and the inlet of the concentrated water tank 22, it is used to measure the flow rate of the concentrated water passing through the first space of the final stage membrane module unit (the example in FIG. 1 is the fifth stage membrane module unit 20). The first flow measurement means is provided with a first flow measurement device 34 . In the piping 62, as the second flow measurement means for measuring the flow rate of the dilution water passing through the second space of the first-stage membrane module unit (the example in FIG. 1 is the first-stage membrane module unit 12), the second flow rate is provided. Assay device 36 . The valve 32 is arranged at the rear stage of the membrane module unit of the final stage (the example of FIG. 1 is the membrane module unit 20 of the fifth stage), for example, based on the measured values of the first flow measuring device 34 and the second flow measuring device 36 And adjust the proportional control valve opening. The water treatment device 1 is equipped with a control device 66; the control device 66 is connected to the first inverter 30, the first flow measuring device 34, and the second flow measuring device 36 through a wired or wireless electrical connection. . The control device 66 can also be connected to the valve 32 through a wired or wireless electrical connection.

The water treatment method and the operation of the water treatment device 1 of this embodiment will be described.

The water treatment device 1 is the following device: using, for example, a multi-stage membrane module with a first space 11 and a second space 13 separated by a semipermeable membrane 15, the water to be treated including the total dissolved solids The first RO concentrated water obtained by the first reverse osmosis membrane treatment device 100 of the reverse osmosis membrane treatment is circulated in series to the first space 11 of the multi-stage membrane module, and then to the final membrane module unit (the example in Figure 1 is, The first space 11 and the second space 13 of the 5th section membrane module unit 20) distribute the concentrated water of its previous section membrane module unit (the example of Fig. 1 is, the 4th section membrane module unit 18), make the final section The dilution water of the membrane module returns and circulates in series to the second space 13 of the previous membrane module, pressurizing the first space 11, so that the water contained in the first space 11 permeates into the second space 13, Concentrate the water. That is, in the water treatment device 1 , the first RO concentrated water is concentrated by the semipermeable membrane 15 , and the concentrated water is further concentrated by the semipermeable membrane 15 of the next stage. To the first space 11 of the first-stage membrane module unit (the example in Figure 1 is the first-stage membrane module unit 12), the first RO concentrated water is supplied; to the first space 11 and the second Both sides of the space 13 are supplied with concentrated water from the preceding stage (in the example of FIG. 1 , the membrane module unit 18 of the fourth stage). Then, the dilution water passing through the second space 13 of the final membrane module is supplied to the second space 13 of the upstream membrane module, and the first space 11 of each membrane module is pressurized to make the first The water contained in the space 11 permeates into the second space 13 .

Specifically, in the water treatment device 1, the treated water including the total dissolved solids is stored in the treated water tank 10 as necessary through the pipe 38, and is pressurized from the treated water tank 10 to 0.1 by the booster pump 26. MPa or higher (pressurization step), it is sent to the first reverse osmosis membrane treatment device 100 through the pipe 40 . In the first reverse osmosis membrane treatment device 100 , the pressurized water to be treated is passed through the first reverse osmosis membrane to obtain first RO permeated water and first RO concentrated water (first reverse osmosis membrane treatment step). The first RO permeated water is discharged through the first RO permeated water pipe 108 . At least a part of the first RO permeate water may be further sent to the third reverse osmosis membrane treatment device 104 as described later, and the reverse osmosis membrane treatment is performed in the third reverse osmosis membrane treatment device 104 (third reverse osmosis membrane treatment step).

The first RO concentrated water is sent to the first space 11 of each membrane module of the first-stage membrane module unit 12 through the first RO concentrated water pipe 106 . On the other hand, from the 5th membrane module unit 20 of the final stage described later, through the second space 13 of the 4th membrane module unit 18, the second space 13 of the 3rd membrane module unit 16, the second The dilution water returned from the second space 13 of the membrane module unit 14 is sent to the second space 13 of each membrane module of the first membrane module unit 12 through the pipe 60 . In each membrane module of the first-stage membrane module unit 12, the first space 11 is pressurized by the pressurization pump 26, so that the water contained in the first space 11 is sent to the second space. 13 Infiltration (concentration step (paragraph 1)).

The concentrated water in the first-stage membrane module unit 12 is sent to the first space 11 of each membrane module in the second-stage membrane module unit 14 through the pipe 42 . On the other hand, from the 5th membrane module unit 20 of the final stage described later, through the second space 13 of the 4th membrane module unit 18 and the second space 13 of the 3rd membrane module unit 16, return The dilution water is sent to the second space 13 of each membrane module of the second-stage membrane module unit 14 through the piping 58 . Same as the first section, in each membrane module of the second section membrane module unit 14, the first space 11 is pressurized, and the water contained in the first space 11 is permeated into the second space 13 (concentration step (paragraph 2)).

The concentrated water in the membrane module unit 14 of the second stage is sent to the first space 11 of each membrane module in the membrane module unit 16 of the third stage through the pipe 44 . On the other hand, the dilution water returned from the fifth-stage membrane module unit 20 of the final stage described later through the second space 13 of the fourth-stage membrane module unit 18 passes through the piping 56 to the third-stage membrane module unit. The second space 13 of each film module of the unit 16 is conveyed. In the same manner as in the first and second stages, in each membrane module unit 16 of the third stage, the first space 11 is pressurized so that the water contained in the first space 11 permeates into the second space 13 (Concentration step (paragraph 3)).

The concentrated water in the membrane module unit 16 of the third stage is sent to the first space 11 of each membrane module in the membrane module unit 18 of the fourth stage through the pipe 46 . On the other hand, the dilution water returned from the fifth-stage membrane module unit 20 of the final stage described later is sent to the second space 13 of each membrane module of the fourth-stage membrane module unit 18 through the pipe 54 . Like the first, second, and third sections, in each membrane module of the fourth section membrane module unit 18, the first space 11 is pressurized so that the water contained in the first space 11 is sent to the second space 13. Infiltration (concentration step (paragraph 4)).

The concentrated water in the fourth-stage membrane module unit 18 is distributed and transported to the first space 11 and the second space 13 of each membrane module in the fifth-stage membrane module unit 20 of the final stage through the pipe 48 . In the same manner as the first to fourth sections, in the fifth section membrane module unit 20, the first space 11 is pressurized so that the water contained in the first space 11 permeates into the second space 13 (concentration step (the fifth section) part)). Here, the pressurizing pump 26, the piping 48, etc. function as supply means for supplying the concentrated water of the previous stage to both the first space and the second space of the final semipermeable membrane module.

The concentrated water of the fifth-stage membrane module unit 20 passes through the piping 50 with the valve 32 open, and is transported and stored to the concentrated water tank 22 as necessary. At least a part of the concentrated water is discharged from the concentrated water tank 22 through the piping 52 by the pump 28 to the outside of the system as treated water. At least a part of the concentrated water may also be sent to the treated water tank 10 and mixed with the treated water in the treated water tank 10 .

The dilution water in the membrane module unit 20 of the fifth stage is sent to the second space 13 of each membrane module in the membrane module unit 18 of the fourth stage through the pipe 54 . As mentioned above, in each membrane module of the fourth stage membrane module unit 18, the first space 11 is pressurized so that the water contained in the first space 11 permeates to the second space 13 (concentrating step (fourth stage) )).

The dilution water in the membrane module unit 18 of the fourth stage is sent to the second space 13 of each membrane module in the membrane module unit 16 of the third stage through the piping 56 . As mentioned above, in each membrane module of the third stage membrane module unit 16, the first space 11 is pressurized so that the water contained in the first space 11 permeates into the second space 13 (concentration step (third stage) )).

The dilution water in the membrane module unit 16 of the third stage is sent to the second space 13 of each membrane module in the membrane module unit 14 of the second stage through the pipe 58 . As mentioned above, in each membrane module of the second stage membrane module unit 14, the first space 11 is pressurized so that the water contained in the first space 11 permeates into the second space 13 (concentration step (second stage) )).

The dilution water in the membrane module unit 14 of the second stage is sent to the second space 13 of each membrane module in the membrane module unit 12 of the first stage through the pipe 60 . As mentioned above, in each membrane module of the first stage membrane module unit 12, the first space 11 is pressurized so that the water contained in the first space 11 permeates into the second space 13 (concentration step (first stage) )).

The dilution water of the membrane module unit 12 of the first stage passes through the piping 62 , is transported and stored in the first dilution water tank 24 as necessary, and is discharged out of the system through the piping 64 . At least a part of the dilution water may be sent to the treated water tank 10 and mixed with the treated water in the treated water tank 10 . At least a part of the dilution water may be further sent to the second reverse osmosis membrane treatment device 102 as described later, and the reverse osmosis membrane treatment may be performed in the second reverse osmosis membrane treatment device 102 (second reverse osmosis membrane treatment step).

In the same way as above, from the treatment object, that is, the treated water including total dissolved solids, etc., to obtain treated water with concentrated total dissolved solids and other substances (concentrated water in the final stage) and dilution water, the reduction of treated water is carried out. Allow.

In the water treatment method and water treatment device 1 of the present embodiment, the flow rate of the concentrated water passing through the first space of the semipermeable membrane module of the final stage is measured (the first flow measurement step), and the flow rate of the concentrated water passing through the first stage semipermeable membrane module is measured. The flow rate of the dilution water in the second space of the group (the second flow measurement step), adjust the flow rate of the first RO concentrated water supplied to the first space of the semi-permeable membrane module in the first stage, so that the flow rate of the concentrated water in the final stage The measured value of the measured value and the measured value of the flow rate of the dilution water in the first stage become the preset target flow value (flow rate adjustment step).

For example, the control device 66 functions as a flow rate adjustment means: adjust the flow rate of the first RO concentrated water supplied to the first space of the first-stage semi-permeable membrane module so that the final flow rate measured by the first flow rate measurement device 34 The measured value of the flow rate of the concentrated water of the section membrane module unit (the example of FIG. 1 is the fifth section membrane module unit 20), and the first section membrane module unit measured by the second flow measurement device 36 ( In the example shown in FIG. 1 , the measured value of the flow rate of the dilution water in the first-stage membrane module unit 12) becomes a preset target flow value. The control device 66, for example, uses an arbitrary arithmetic formula to calculate the driving frequency, outputs a command signal corresponding to the calculated value to the first inverter 30 to control the booster pump 26, and adjusts the pressure to the first stage of the membrane module unit (Fig. An example of 1 is the flow rate of the first RO concentrated water supplied to the first space 11 of the first-stage membrane module unit 12), so that the measured values of the first flow measuring device 34 and the second flow measuring device 36 become preset Target traffic value.

As a result, in the concentration treatment of water using the semi-permeable membrane module, even if the volume of the discharged water is reduced by the reverse osmosis membrane method, and the water quality of the treated water (raw water) changes, it can still be stable. deal with.

Specifically, for example, the pressure pump 26 is activated, the valve 32 is fully opened (opening degree 100%), and the output value of the first inverter 30 accompanying the pressure pump 26 is gradually increased. When the measured value of the first flow rate measuring device 34 reaches the target flow rate, the valve 32 is closed by, for example, a predetermined arbitrary ratio (for example, the degree of opening is set to 10% relative to the full opening). Since the measured value of the first flow measuring device 34 decreases, the output of the first inverter 30 of the booster pump 26 is increased until the measured value of the first flow measuring device 34 reaches the target flow rate. When the valve 32 is closed, the measured value of the second flow rate measuring device 36 increases. Then, the output of the first inverter 30 is increased → the measured value of the first flow measuring device 34 is increased → the valve 32 is closed → the measured value of the first flow measuring device 34 is decreased, and the measured value of the second flow measuring device 36 is increased The operation is repeated, and the measured values of the first flow measuring device 34 and the second flow measuring device 36 are adjusted to the target flow.

When the recovery rate of treated water changes, for example, the output value of the first inverter 30 and the opening of the valve 32 are automatically controlled to change the flow rate of the first RO concentrated water so that the measured value according to the first flow measuring device 34 The recovery rate of treated water (recovery rate=second flow rate measurement value/(first flow rate measurement value+second flow rate measurement value)×100) of the measured value of the second flow rate measuring device 36 should be as constant as possible. When the flow rate of the first space measured by the first flow measuring device 34 is lower than the set flow rate, the output value of the first inverter 30 is fixed and the opening of the valve 32 is increased (that is, the valve is opened. ). The adjustment of the opening degree of the valve 32, for example, can repeat the following steps: open a predetermined arbitrary ratio (for example, make the opening degree 10% relative to the full opening), and observe the valve at a predetermined time (for example, 1 minute). The state of the flow rate in the first space measured by the first flow rate measuring device 34 . Alternatively, the opening degree of the valve 32 may be fixed, the output value of the first inverter 30 may be increased, and the flow rate of the first space may be increased.

When the flow rate in the first space measured by the first flow rate measuring device 34 is larger than the set flow rate, the opening degree of the valve 32 may be fixed and the output of the first inverter 30 may be lowered. However, when the pressurizing pump 26 reaches the output lower limit value for operation guarantee, the opening degree of the valve 32 is decreased (the valve is closed). The adjustment of the opening degree of the valve 32, for example, can repeat the following steps: close a predetermined arbitrary ratio (for example, make the opening degree 10% relative to the full opening), and observe at a predetermined time (for example, 1 minute). The state of the flow rate in the first space measured by the first flow rate measuring device 34 . Alternatively, the output value of the first inverter 30 may be fixed, the opening of the valve 32 may be reduced, and the flow rate of the first space may be reduced.

When the flow rate of the second space measured by the second flow measuring device 36 is lower than the set flow rate, the output value of the first inverter 30 is fixed to reduce the flow rate of the valve 32 because the flow rate of the first space becomes larger. Just open. Alternatively, the opening degree of the valve 32 may be fixed to increase the output value of the first inverter 30 . When the flow rate of the second space measured by the second flow measuring device 36 is larger than the set flow rate, since the flow rate of the first space becomes smaller, the output value of the first inverter 30 is fixed, and the output value of the valve 32 is increased. Just open. Alternatively, the opening degree of the valve 32 may be fixed to lower the output value of the first inverter 30 .

In addition to the valve 32, the proportional control valve that adjusts the opening according to the measured values of the first flow measuring device 34 and the second flow measuring device 36 can also be installed in the piping of the first space 11, such as piping 106, 42, 44, 46. , 48 are provided with more than one; the opening degree of the valve can be adjusted manually, and the opening degree of the valve can also be adjusted automatically by the control device 66 .

In addition to the first flow measuring device 34 for measuring the flow rate of concentrated water passing through the first space of the final membrane module unit, the flow measuring device for measuring the flow rate of the first space 11 can also be installed in the piping of the first space 11, For example, one or more pipes are provided in the pipes 106 , 42 , 44 , 46 , and 48 .

In addition to the second flow measuring device 36 for measuring the flow rate of the dilution water passing through the second space of the first-stage membrane module unit, the flow measuring device for measuring the flow rate of the second space 13 can also be installed in the piping of the second space 13. , For example, one or more are provided in the piping 54, 56, 58, 60.

In the water treatment device 1, it is also possible to further measure the flow rate of the dilution water passing through the second space of the final-stage membrane module unit, adjust the flow rate of the first RO concentrated water supplied to the first space of the first-stage membrane module unit, and The flow rate of dilution water supplied to the second space before the final stage, so that the measured value of the flow rate of concentrated water in the final stage, the measured value of the flow rate of dilution water in the first stage, and the flow rate of dilution water in the final stage The measured value becomes the preset target flow value. A water treatment device of these configurations is shown in FIG. 2 .

The water treatment device 2 shown in FIG. 2 further includes a second dilution water tank 68 for storing dilution water from the membrane module unit in the final stage (the example in FIG. 2 is dilution water from the membrane module unit 20 in the fifth stage). In the water treatment device 2 , the second space outlet of each membrane module of the fifth-stage membrane module unit 20 and the dilution water inlet of the second dilution water tank 68 are connected by a pipe 76 . The outlet of the second dilution water tank 68 is connected in parallel to the inlet of the second space of each membrane module of the fourth-stage membrane module unit 18 through the second booster pump 70 through the pipe 78 . In addition, the water treatment device 2 may or may not include the concentrated water tank 22, the pump 28, and the piping 52. The water treatment device 2 may or may not include the first dilution water tank 24 and the piping 64 .

The dilution water of the membrane module unit 20 in the fifth stage is sent to the second dilution water tank 68 through the pipe 76 and stored, and then is transferred from the second dilution water tank 68 to the fourth stage through the pipe 78 by the second booster pump 70 The second space 13 of each film module of the film module unit 18 is conveyed. As mentioned above, in each membrane module of the fourth stage membrane module unit 18, the first space 11 is pressurized so that the water contained in the first space 11 permeates to the second space 13 (concentrating step (fourth stage) )).

In the piping 76, a third flow measuring means is provided as a third flow measuring means for measuring the flow rate of the dilution water passing through the second space of the final membrane module unit (the fifth membrane module unit 20 in the example of FIG. 2 ). Device 74. The second pressurizing pump 70 is installed at the rear stage of the final stage membrane module unit (the example of FIG. 2 is the fifth stage membrane module unit 20), and is driven, for example, at a rotational speed corresponding to the input driving frequency to suck in The dilution water of the final membrane module unit (the example of Figure 2 is the dilution water of the fifth membrane module unit 20) and the membrane module unit of the previous section (the example of Figure 2 is the fourth membrane module unit 18) The second booster pump for spraying. The second booster pump 70 is provided with, for example, a second inverter 72 that outputs a driving frequency corresponding to an input command signal to the second booster pump 70 . The installation places of the second dilution water tank 68, the second booster pump 70, and the flow measuring device 74 are not limited to the positions shown in FIG. , 60 any one. The water treatment device 2 is equipped with a control device 66; the control device 66 is connected to the first inverter 30, the second inverter 72, the first flow measuring device 34, the first 2. The flow rate measuring device 36 and the third flow rate measuring device 74 are connected. The control device 66 can also be connected to the valve 32 through a wired or wireless electrical connection.

In the water treatment method and water treatment device 2 of the present embodiment, the flow rate of the concentrated water passing through the first space of the membrane module unit of the final stage is measured (the first flow measurement step), and the flow rate of the concentrated water passing through the membrane module unit of the first stage is measured. The flow rate of the dilution water in the second space (the second flow measurement step), and measure the flow rate of the dilution water passing through the second space of the final membrane module unit (the third flow measurement step), and adjust to the first membrane module unit The flow rate of the first RO concentrated water supplied in the first space, and the flow rate of the dilution water supplied to the second space of the membrane module unit before the final stage, so that the measured value of the flow rate of the concentrated water in the final stage, the first The measured value of the flow rate of the dilution water in the stage and the measured value of the flow rate of the dilution water in the final stage become the preset target flow value (flow rate adjustment step).

For example, the control device 66 functions as a flow adjustment means: adjust the flow rate of the first RO concentrated water supplied to the first space of the first-stage membrane module unit, and the flow rate to the second space of the membrane module unit one stage before the final stage The flow rate of the dilution water to be supplied is such that the measured value of the flow rate of the concentrated water in the final stage membrane module unit (the example in FIG. 2 is the fifth stage membrane module unit 20) measured by the first flow rate measuring device 34 , the measured value of the flow rate of the dilution water of the first stage membrane module unit (the example of FIG. 2 is the first stage membrane module unit 12) measured by the second flow measuring device 36, and the measured value by the third flow rate The measured value of the flow rate of the dilution water of the last-stage membrane module unit measured by the measuring device 74 becomes a preset target flow value. The control device 66, for example, calculates the drive frequency using an arbitrary arithmetic formula, and outputs a command signal corresponding to the calculated value to the first inverter 30 to control the booster pump 26, and outputs to the second inverter 72 to control the second inverter 72. 2. The pressurizing pump 70 is used to adjust the first RO concentrated water supplied to the first space 11 of the first stage membrane module unit (the example in FIG. 2 is the first stage membrane module unit 12) and the water to the first stage before the final stage. The flow rate of the dilution water supplied by the second space 13 of the membrane module unit (the example of FIG. 2 is the fourth stage membrane module unit 18) so that the first flow measuring device 34, the second flow measuring device 36 and the third flow measuring device The measured value of the flow measurement device 74 becomes a preset target flow value.

As a result, in the concentration treatment of water using the semi-permeable membrane module, even if the volume of the discharged water is reduced by the reverse osmosis membrane method, and the water quality of the treated water (raw water) changes, it can still become relatively stable. processing. By storing the dilution water passing through the second space of the final stage in the second dilution water tank 68, even if the water balance between the first space and the second space is out of balance due to the change of the water quality of the treated water, it is still easy to adjust the flow rate . In addition, by using the second pressurizing pump 70 as the second pressurizing pump that inhales the dilution water of the membrane module unit of the last stage and sprays it to the membrane module unit of the previous stage, the number of stages in the membrane module unit increases. If the pressure required for water passage is insufficient by means of the booster pump 26, the load of the booster pump 26 can be reduced, and the insufficient pressure required for water passage can be suppressed.

Specifically, for example, the pressure pump 26 is activated, the valve 32 is fully opened (opening degree 100%), and the output value of the first inverter 30 accompanying the pressure pump 26 is gradually increased. When the measured value of the first flow measuring device 34 reaches the target flow rate, the valve 32 is closed by, for example, a predetermined arbitrary ratio (for example, the degree of opening is set to 10% relative to full opening). Since the measured value of the first flow measuring device 34 decreases, the output of the first inverter 30 of the booster pump 26 is increased until the measured value of the first flow measuring device 34 reaches the target flow rate. When the valve 32 is closed, the measured value of the third flow rate measuring device 74 increases. Then, the output of the first inverter 30 is increased → the measured value of the first flow measuring device 34 is increased → the valve 32 is closed → the measured value of the first flow measuring device 34 is decreased, and the measured value of the third flow measuring device 74 is increased The operation is repeated, and the measured values of the first flow measuring device 34 and the third flow measuring device 74 are adjusted to the target flow. In addition, it is also possible to adjust the measured value of the second flow rate measuring device 36 to the target flow rate by setting the output value of the second inverter 72 accompanying the second booster pump 70 .

When the recovery rate of treated water changes, for example, the output value of the first inverter 30, the output value of the second inverter 72, and the opening of the valve 32 are automatically controlled to change the flow rate of the first RO concentrated water, and The flow rate of the dilution water is such that the recovery rate of the treated water based on the measured value of the first flow measuring device 34 and the measured value of the second flow measuring device 36 is as constant as possible. When the flow rate of the first space measured by the first flow measuring device 34 is lower than the set flow rate, the output value of the first inverter 30 is fixed and the opening of the valve 32 is increased (that is, the valve is opened. ). The adjustment of the opening degree of the valve 32, for example, can repeat the following steps: close a predetermined arbitrary ratio (for example, make the opening degree 10% relative to the full opening), and observe at a predetermined time (for example, 1 minute). The state of the flow rate in the first space measured by the first flow rate measuring device 34 . Alternatively, the opening degree of the valve 32 may be fixed, the output value of the first inverter 30 may be increased, and the flow rate of the first space may be increased.

When the flow rate in the first space measured by the first flow rate measuring device 34 is larger than the set flow rate, the opening degree of the valve 32 may be fixed and the output of the first inverter 30 may be lowered. However, when the pressurizing pump 26 reaches the output lower limit value for operation guarantee, the opening degree of the valve 32 is decreased (the valve is closed). The adjustment of the opening degree of the valve 32, for example, repeats the following steps: closing at a predetermined arbitrary ratio (for example, making the opening degree 10% relative to full opening), at a predetermined time (for example, 1 minute), Observe the state of the flow rate in the first space measured by the first flow rate measuring device 34 . Alternatively, the output value of the first inverter 30 may be fixed, the opening of the valve 32 may be reduced, and the flow rate of the first space may be reduced.

When the flow rate in the second space measured by the second flow measuring device 36 is lower than the set flow rate, the opening of the valve 32 is fixed and the output value of the second inverter 72 is increased. When the flow rate in the second space measured by the second flow rate measuring device 36 is larger than the set flow rate, the opening degree of the valve 32 is fixed and the output value of the second inverter 72 may be lowered.

When the flow rate of the second space measured by the third flow measuring device 74 is lower than the set flow rate, the output value of the first inverter 30 is fixed to reduce the flow rate of the valve 32 because the flow rate of the first space becomes larger. Just open. Alternatively, the opening degree of the valve 32 may be increased to increase the output value of the first inverter 30 . When the flow rate of the second space measured by the third flow measuring device 74 is larger than the set flow rate, since the flow rate of the first space becomes smaller, the output value of the first inverter 30 is fixed, and the output value of the valve 32 is increased. Just open. Alternatively, the opening degree of the valve 32 may be fixed to lower the output value of the first inverter 30 .

The proportional control valve that adjusts the opening according to the measured values of the first flow measuring device 34, the second flow measuring device 36, and the third flow measuring device 74, in addition to the valve 32, can also be installed in the piping of the first space 11, for example, in the piping More than one of 106, 42, 44, 46, 48 is set; the opening degree of the valve can be adjusted manually, and the opening degree of the valve can also be adjusted automatically by the control device 66.

In addition to the first flow measuring device 34 for measuring the flow rate of concentrated water passing through the first space of the final membrane module unit, the third flow measuring device 74 for measuring the flow rate of dilution water passing through the second space of the final membrane module unit Alternatively, one or more flow measuring devices for measuring the flow rate of the first space 11 may be installed in the piping of the first space 11 , for example, in the piping 106 , 42 , 44 , 46 , 48 .

In addition to the second flow measuring device 36 for measuring the flow rate of the dilution water passing through the second space of the first-stage membrane module unit, the flow measuring device for measuring the flow rate of the second space 13 can also be installed in the piping of the second space 13. , For example, one or more are provided in the piping 78 , 56 , 58 , 60 .

Also in the piping of the first space 11, such as the piping 106, 42, 44, 46, 48, the measured values according to the first flow measuring device 34, the second flow measuring device 36 and the third flow measuring device 74 are adjusted. Degree of proportional control valve, set more than one.

In the water treatment device 2, the second dilution water tank 68 may not be provided. Fig. 3 shows a water treatment device with these configurations.

In the water treatment device 3 shown in FIG. 3 , the piping 54 serves as a means for measuring the flow rate of the dilution water passing through the second space of the final stage membrane module unit (the example in FIG. 3 is the fifth stage membrane module unit 20 ). As the third flow measurement means, a third flow measurement device 84 is provided. Connect the second space outlet of each membrane module of the fifth stage membrane module unit 20 and the second space inlet of each membrane module of the fourth stage membrane module unit 18 through the second booster pump 80 through the piping 54 while connected in parallel. In addition, the water treatment device 3 may or may not include the concentrated water tank 22, the pump 28, and the piping 52. The water treatment device 3 may or may not include the first dilution water tank 24 and the piping 64 .

The second booster pump 80 is provided with, for example, a second inverter 82 that outputs a drive frequency corresponding to an input command signal to the second booster pump 80 . The water treatment device 3 is equipped with a control device 66; the control device 66 is connected to the first inverter 30, the second inverter 82, the first flow measuring device 34, the first 2. The flow rate measuring device 36 and the third flow rate measuring device 84 are connected. The control device 66 can also be connected to the valve 32 through a wired or wireless electrical connection.

In the water treatment method and water treatment device 3 of the present embodiment, the flow rate of the concentrated water passing through the first space of the final stage membrane module unit is measured (the first flow measurement step), and the flow rate of the concentrated water passing through the first stage membrane module unit is measured. The flow rate of the dilution water in the second space (the second flow measurement step), and measure the flow rate of the dilution water passing through the second space of the final membrane module unit (the third flow measurement step), and adjust to the first membrane module unit The flow rate of the first RO concentrated water supplied in the first space, and the flow rate of the dilution water supplied to the second space of the membrane module unit before the final stage, so that the measured value of the flow rate of the concentrated water in the final stage, the first The measured value of the flow rate of the dilution water in the stage and the measured value of the flow rate of the dilution water in the final stage become the preset target flow value (flow rate adjustment step).

For example, the control device 66 functions as a flow adjustment means: adjust the flow rate of the first RO concentrated water supplied to the first space of the first-stage membrane module unit, and the flow rate to the second space of the membrane module unit one stage before the final stage The flow rate of the dilution water to be supplied is such that the measured value of the flow rate of the concentrated water in the final stage membrane module unit (the example in FIG. 2 is the fifth stage membrane module unit 20) measured by the first flow rate measuring device 34 , the measured value of the flow rate of the dilution water of the first stage membrane module unit (the example of FIG. 2 is the first stage membrane module unit 12) measured by the second flow measuring device 36, and the measured value by the third flow rate The measured value of the flow rate of the dilution water of the last-stage membrane module unit measured by the measuring device 84 becomes a preset target flow value. The control device 66, for example, calculates the drive frequency using an arbitrary arithmetic formula, outputs a command signal corresponding to the calculated value to the first inverter 30 to control the booster pump 26, and outputs to the second inverter 82 to control the second inverter 82. 2. The pressurizing pump 80 is used to adjust the first RO concentrated water supplied to the first space 11 of the first stage membrane module unit (the example in FIG. 2 is the first stage membrane module unit 12) and the water to the first stage before the final stage. The flow rate of the dilution water supplied by the second space 13 of the membrane module unit (the example of FIG. 2 is the fourth stage membrane module unit 18) so that the first flow measuring device 34, the second flow measuring device 36 and the third flow measuring device The measured value of the flow measurement device 84 becomes a preset target flow value.

As a result, in the concentration treatment of water using a multi-stage semi-permeable membrane module, even if the volume of the discharged water is reduced by the reverse osmosis membrane method, and the water quality of the treated water (raw water) changes, it can still become more stable processing. In addition, by using the second pressurizing pump 80 as the second pressurizing pump that inhales the dilution water of the membrane module unit of the last stage and sprays it to the membrane module unit of the previous stage, the number of stages in the membrane module unit increases, if only If the pressure required for water passage is insufficient by means of the booster pump 26, the load of the booster pump 26 can be reduced, and the insufficient pressure required for water passage can be suppressed.

The outline of another example of the water treatment device according to the embodiment of the present invention is shown in FIG. 4 .

In the water treatment device 4 shown in Figure 4, it is different from the water treatment device 1 shown in Figure 1 in the following points: the first space outlet of each membrane module of the 4th section membrane module unit 18 is connected to the 5th section membrane The first space inlet of each membrane module of module unit 20 is connected in parallel by piping 88; , are connected in parallel through the pipe 90 through the valve 86 .

The water treatment device 4 is the following device: using a multi-stage membrane module having a first space 11 and a second space 13 separated by a semipermeable membrane 15, the first RO concentrated water is sent to the first space of the multi-stage membrane module 11 circulates in series, and distributes the concentrated water of the final stage membrane module unit to the second space 13 of the final stage membrane module unit (the example of FIG. 4 is the fifth stage membrane module unit 20), so that the final stage membrane module unit The dilution water of the group returns and circulates in series to the second space 13 of the previous membrane module, pressurizing the first space 11, so that the water contained in the first space 11 permeates into the second space 13, and the water concentrate. That is, in the water treatment device 4 , the first RO concentrated water is concentrated by the semipermeable membrane 15 , and the concentrated water is further concentrated by the semipermeable membrane 15 of the next stage. To the first space 11 of the first-stage membrane module unit (the example in Figure 4 is the first-stage membrane module unit 12), the first RO concentrated water is supplied; the concentrated water passes through the final stage of the membrane module unit (Figure 1 For example, after the first space 11 of the fifth-stage membrane module unit (20), at least a part of the concentrated water in the final stage is supplied to the second space 13 of the final-stage membrane module. Then, the dilution water passing through the second space 13 of the final membrane module is supplied to the second space 13 of the upstream membrane module, and the first space 11 of each membrane module is pressurized to make the first The water contained in the space 11 permeates into the second space 13 .

Specifically, in the water treatment device 4, the treated water including the total dissolved solids is stored in the treated water tank 10 as necessary through the pipe 38, and is pressurized from the treated water tank 10 to 0.1 by the booster pump 26. MPa or higher (pressurization step), it is sent to the first reverse osmosis membrane treatment device 100 through the pipe 40 . In the first reverse osmosis membrane treatment device 100 , the pressurized water to be treated is passed through the first reverse osmosis membrane to obtain first RO permeated water and first RO concentrated water (first reverse osmosis membrane treatment step). The first RO permeated water is discharged through the first RO permeated water pipe 108 . At least a part of the first RO permeate water may be further sent to the third reverse osmosis membrane treatment device 104 as described later, and the reverse osmosis membrane treatment is performed in the third reverse osmosis membrane treatment device 104 (third reverse osmosis membrane treatment step).

The first RO concentrated water is sent to the first space 11 of each membrane module of the first-stage membrane module unit 12 through the first RO concentrated water pipe 106 . On the other hand, from the 5th membrane module unit 20 of the final stage described later, through the second space 13 of the 4th membrane module unit 18, the second space 13 of the 3rd membrane module unit 16, the second The dilution water returned from the second space 13 of the membrane module unit 14 is sent to the second space 13 of each membrane module of the first membrane module unit 12 through the pipe 60 . In each membrane module of the first-stage membrane module unit 12 , the first space 11 is pressurized, and the water contained in the first space 11 is permeated into the second space 13 (concentration step (first stage)).

The concentrated water in the first-stage membrane module unit 12 is sent to the first space 11 of each membrane module in the second-stage membrane module unit 14 through the pipe 42 . On the other hand, from the 5th membrane module unit 20 of the final stage described later, through the second space 13 of the 4th membrane module unit 18 and the second space 13 of the 3rd membrane module unit 16, return The dilution water is sent to the second space 13 of each membrane module of the second-stage membrane module unit 14 through the piping 58 . Same as the first section, in each membrane module of the second section membrane module unit 14, the first space 11 is pressurized, and the water contained in the first space 11 is permeated into the second space 13 (concentration step (paragraph 2)).

The concentrated water in the membrane module unit 14 of the second stage is sent to the first space 11 of each membrane module in the membrane module unit 16 of the third stage through the pipe 44 . On the other hand, the dilution water returned from the fifth-stage membrane module unit 20 of the final stage described later through the second space 13 of the fourth-stage membrane module unit 18 passes through the piping 56 to the third-stage membrane module unit. The second space 13 of each film module of the unit 16 is conveyed. In the same manner as in the first and second stages, in each membrane module unit 16 of the third stage, the first space 11 is pressurized so that the water contained in the first space 11 permeates into the second space 13 (Concentration step (paragraph 3)).

The concentrated water in the membrane module unit 16 of the third stage is sent to the first space 11 of each membrane module in the membrane module unit 18 of the fourth stage through the pipe 46 . On the other hand, the dilution water returned from the fifth-stage membrane module unit 20 of the final stage described later is sent to the second space 13 of each membrane module of the fourth-stage membrane module unit 18 through the pipe 92 . Like the first, second, and third sections, in each membrane module of the fourth section membrane module unit 18, the first space 11 is pressurized so that the water contained in the first space 11 is sent to the second space 13. Infiltration (concentration step (paragraph 4)).

The concentrated water in the fourth-stage membrane module unit 18 is sent to the first space 11 of each membrane module in the fifth-stage membrane module unit 20 of the last stage through the pipe 88 . On the other hand, concentrated water returned from the fifth-stage membrane module unit 20 of the final stage described later is sent to the second space 13 of each membrane module of the fifth-stage membrane module unit 20 through the pipe 90 . In the same manner as the first to fourth sections, in the fifth section membrane module unit 20, the first space 11 is pressurized so that the water contained in the first space 11 permeates into the second space 13 (concentration step (the fifth section) part)).

The concentrated water of the fifth-stage membrane module unit 20 passes through the piping 50 with the valve 32 open, and is transported and stored to the concentrated water tank 22 as necessary. With the valve 86 closed, at least a part of the concentrated water is discharged from the concentrated water tank 22 through the piping 52 by the pump 28 to the outside of the system as treated water. At least a part of the concentrated water may also be sent to the treated water tank 10 and mixed with the treated water in the treated water tank 10 .

At least a part of the concentrated water in the fifth-stage membrane module unit 20 is passed from the concentrated water tank 22 through the pump 28 to each membrane of the fifth-stage membrane module unit 20 through the pipe 52 and the pipe 90 with the valve 86 open. The second space 13 of the module is transported. As mentioned above, in each membrane module of the 5th section membrane module unit 20, the first space 11 is pressurized so that the water contained in the first space 11 permeates into the second space 13 (concentrating step (5th section) )). Here, the pump 28, the pipes 52 and 90, etc. function as supply means for supplying at least a part of the concentrated water in the final stage to the second space of the semipermeable membrane module in the final stage. In addition, as shown in the water treatment device 17 of Figure 10, the concentrated water tank 22 and the pump 28 are not provided, and the piping 50 from the first space outlet of each membrane module of the 5th stage membrane module unit 20 is connected to the valve. 32 is branched on the front stage side, and the piping 91 through the valve 87 is connected to the second space inlet of each membrane module unit 20 of the fifth stage membrane module unit, so that the concentrated water of the fifth stage membrane module unit 20 is passed through the valve 87 In the opened state, it is sent to the second space 13 of each membrane module of the fifth-stage membrane module unit 20 through the piping 50 and the piping 91 . In addition, the water treatment device 4 may or may not include the first dilution water tank 24 and the piping 64 .

The dilution water in the membrane module unit 20 of the fifth stage is sent to the second space 13 of each membrane module in the membrane module unit 18 of the fourth stage through the pipe 92 . As mentioned above, in each membrane module of the fourth stage membrane module unit 18, the first space 11 is pressurized so that the water contained in the first space 11 permeates to the second space 13 (concentrating step (fourth stage) )).

The dilution water in the membrane module unit 18 of the fourth stage is sent to the second space 13 of each membrane module in the membrane module unit 16 of the third stage through the piping 56 . As mentioned above, in each membrane module of the third stage membrane module unit 16, the first space 11 is pressurized so that the water contained in the first space 11 permeates into the second space 13 (concentration step (third stage) )).

The dilution water in the membrane module unit 16 of the third stage is sent to the second space 13 of each membrane module in the membrane module unit 14 of the second stage through the pipe 58 . As mentioned above, in each membrane module of the second stage membrane module unit 14, the first space 11 is pressurized so that the water contained in the first space 11 permeates into the second space 13 (concentration step (second stage) )).

The dilution water in the membrane module unit 14 of the second stage is sent to the second space 13 of each membrane module in the membrane module unit 12 of the first stage through the pipe 60 . As mentioned above, in each membrane module of the first stage membrane module unit 12, the first space 11 is pressurized so that the water contained in the first space 11 permeates into the second space 13 (concentration step (first stage) )).

The dilution water of the membrane module unit 12 of the first stage passes through the piping 62 , is transported and stored in the first dilution water tank 24 as necessary, and is discharged out of the system through the piping 64 . At least a part of the dilution water may be sent to the treated water tank 10 and mixed with the treated water in the treated water tank 10 . At least a part of the dilution water may be further sent to the second reverse osmosis membrane treatment device 102 as described later, and the reverse osmosis membrane treatment may be performed in the second reverse osmosis membrane treatment device 102 (second reverse osmosis membrane treatment step).

In the same way as above, from the treatment object, that is, the treated water including total dissolved solids, etc., to obtain treated water with concentrated total dissolved solids and other substances (concentrated water in the final stage) and dilution water, the reduction of treated water is carried out. Allow.

For example, the control device 66 functions as a flow rate adjustment means: adjust the flow rate of the first RO concentrated water supplied to the first space of the first stage membrane module unit so that the flow rate of the final stage measured by the first flow rate measuring device 34 The measured value of the flow rate of the concentrated water of the membrane module unit (the example in FIG. 1 is the fifth stage membrane module unit 20), and the first stage membrane module unit (Fig. An example of 1 is that the measured value of the flow rate of dilution water in the first-stage membrane module unit 12) becomes a preset target flow rate value. The control device 66, for example, uses an arbitrary arithmetic formula to calculate the driving frequency, outputs a command signal corresponding to the calculated value to the first inverter 30 to control the booster pump 26, and adjusts the pressure to the first stage of the membrane module unit (Fig. An example of 1 is the flow rate of the first RO concentrated water supplied to the first space 11 of the first-stage membrane module unit 12), so that the measured values of the first flow measuring device 34 and the second flow measuring device 36 become preset Target traffic value.

As a result, in the concentration treatment of water using the semi-permeable membrane module, even if the volume of the discharged water is reduced by the reverse osmosis membrane method, and the water quality of the treated water (raw water) changes, it can still be stable. deal with.

In the water treatment device 4, also can be the same as the water treatment device 2 shown in Figure 2, further measure the flow rate of the dilution water passing through the second space of the final stage membrane module unit, adjust the flow rate to the first stage membrane module unit The flow rate of the first RO concentrated water supplied to the first space, and the flow rate of the diluted water supplied to the second space before the final stage, so that the measured value of the flow rate of the concentrated water in the final stage and the flow rate of the diluted water in the first stage The measured value of the flow rate and the measured value of the flow rate of the dilution water in the final stage become the preset target flow value. Figure 5 shows a water treatment device with these configurations.

The water treatment device 5 shown in FIG. 5 further includes a second dilution water tank 68 for storing dilution water from the last-stage membrane module unit (in the example of FIG. 5 , dilution water from the fifth-stage membrane module unit 20 ). In the water treatment device 5 , the second space outlet of each membrane module of the fifth-stage membrane module unit 20 and the dilution water inlet of the second dilution water tank 68 are connected by a pipe 94 . The outlet of the second dilution water tank 68 is connected in parallel to the inlet of the second space of each membrane module of the fourth-stage membrane module unit 18 through the second booster pump 70 through the pipe 78 . In addition, also can be the same as the water treatment device 17 of Fig. 10, do not set concentrated water tank 22, pump 28, and from the piping 50 of the first space outlet of each membrane module group of the 5th stage membrane module unit 20 in the valve 32 is branched on the front stage side, and the piping 91 through the valve 87 is connected to the second space inlet of each membrane module unit 20 of the fifth stage membrane module unit, so that the concentrated water of the fifth stage membrane module unit 20 is passed through the valve 87 In the opened state, it is sent to the second space 13 of each membrane module of the fifth-stage membrane module unit 20 through the piping 50 and the piping 91 . In addition, the water treatment device 5 may or may not include the first dilution water tank 24 and the piping 64 .

The dilution water of the membrane module unit 20 in the fifth stage is sent to the second dilution water tank 68 through the pipe 94 and stored, and then is transferred from the second dilution water tank 68 to the fourth stage through the pipe 78 by the second booster pump 70 The second space 13 of each film module of the film module unit 18 is conveyed. As mentioned above, in each membrane module of the fourth stage membrane module unit 18, the first space 11 is pressurized so that the water contained in the first space 11 permeates to the second space 13 (concentrating step (fourth stage) )).

In the piping 94, a third flow measurement means is provided as a third flow measurement means for measuring the flow rate of dilution water passing through the second space of the final stage membrane module unit (the example in FIG. 5 is the fifth stage membrane module unit 20). Device 74. The second pressurizing pump 70 is installed at the rear stage of the final stage membrane module unit (the example of FIG. 2 is the fifth stage membrane module unit 20), and is driven, for example, at a rotational speed corresponding to the input driving frequency to suck in The dilution water of the final membrane module unit (the example of Figure 2 is the dilution water of the fifth membrane module unit 20) and the membrane module unit of the previous section (the example of Figure 2 is the fourth membrane module unit 18) The second booster pump for spraying. The second booster pump 70 is provided with, for example, a second inverter 72 that outputs a driving frequency corresponding to an input command signal to the second booster pump 70 . In addition, the installation places of the second dilution water tank 68, the second booster pump 70, and the flow measuring device 74 are not limited to the positions shown in FIG. , 58, 60 any one. The water treatment device 5 is equipped with a control device 66; the control device 66 is connected with the first inverter 30, the second inverter 72, the first flow measuring device 34, the first 2. The flow rate measuring device 36 and the third flow rate measuring device 74 are connected. The control device 66 can also be connected to the valve 32 through a wired or wireless electrical connection.

In the water treatment method and water treatment device 5 of the present embodiment, the flow rate of the concentrated water passing through the first space of the final stage membrane module unit is measured (the first flow measurement step), and the flow rate of the concentrated water passing through the first stage membrane module unit is measured. The flow rate of the dilution water in the second space (the second flow measurement step), and measure the flow rate of the dilution water passing through the second space of the final membrane module unit (the third flow measurement step), and adjust to the first membrane module unit The flow rate of the first RO concentrated water supplied in the first space, and the flow rate of the dilution water supplied to the second space of the membrane module unit before the final stage, so that the measured value of the flow rate of the concentrated water in the final stage, the first The measured value of the flow rate of the dilution water in the stage and the measured value of the flow rate of the dilution water in the final stage become the preset target flow value (flow rate adjustment step).

For example, the control device 66 functions as a flow adjustment means: adjust the flow rate of the first RO concentrated water supplied to the first space of the first-stage membrane module unit, and the flow rate to the second space of the membrane module unit one stage before the final stage The flow rate of the dilution water supplied is such that the measured value of the flow rate of the concentrated water in the last stage membrane module unit (the example in FIG. 5 is the fifth stage membrane module unit 20) measured by the first flow rate measuring device 34 , the measured value of the flow rate of the dilution water of the first stage membrane module unit (the example of FIG. 5 is the first stage membrane module unit 12) measured by the second flow rate measuring device 36, and the measured value by the third flow rate The measured value of the flow rate of the dilution water of the last-stage membrane module unit measured by the measuring device 74 becomes a preset target flow value. The control device 66, for example, calculates the drive frequency using an arbitrary arithmetic formula, and outputs a command signal corresponding to the calculated value to the first inverter 30 to control the booster pump 26, and outputs to the second inverter 72 to control the second inverter 72. 2. The pressurizing pump 70 is used to adjust the first RO concentrated water supplied to the first space 11 of the first stage of the membrane module unit (the example in FIG. 5 is the first stage of the membrane module unit 12) and the water to the first stage before the final stage. The flow rate of the dilution water supplied by the second space 13 of the membrane module unit (the example of FIG. 5 is the fourth stage membrane module unit 18) so that the first flow measuring device 34, the second flow measuring device 36 and the third flow measuring device The measured value of the flow measurement device 74 becomes a preset target flow value.

As a result, in the concentration treatment of water using the semi-permeable membrane module, even if the volume of the discharged water is reduced by the reverse osmosis membrane method, and the water quality of the treated water (raw water) changes, it can still become relatively stable. processing. By storing the dilution water passing through the second space of the final stage in the second dilution water tank 68, even if the water balance between the first space and the second space is out of balance due to the change of the water quality of the treated water, it is still easy to adjust the flow rate . In addition, by using the second pressurizing pump 70 as the second pressurizing pump that inhales the dilution water of the membrane module unit of the last stage and sprays it to the membrane module unit of the previous stage, the number of stages in the membrane module unit increases. If the pressure required for water passage is insufficient by means of the booster pump 26, the load of the booster pump 26 can be reduced, and the insufficient pressure required for water passage can be suppressed.

In the water treatment device 5, like the water treatment device 3 shown in FIG. 3, the second dilution water tank 68 may not be provided. Figure 6 shows a water treatment device of these configurations.

In the water treatment device 6 shown in FIG. 6, the piping 92 serves as a means for measuring the flow rate of the dilution water passing through the second space of the final stage membrane module unit (the example in FIG. 6 is the fifth stage membrane module unit 20). As the third flow measurement means, a third flow measurement device 84 is provided. Connect the second space outlet of each membrane module of the fifth stage membrane module unit 20 and the second space inlet of each membrane module of the fourth stage membrane module unit 18 through the second booster pump 80 through the piping 92 while connected in parallel. In addition, also can be the same as the water treatment device 17 of Fig. 10, do not set concentrated water tank 22, pump 28, and from the piping 50 of the first space outlet of each membrane module group of the 5th stage membrane module unit 20 in the valve 32 is branched on the front stage side, and the piping 91 through the valve 87 is connected to the second space inlet of each membrane module unit 20 of the fifth stage membrane module unit, so that the concentrated water of the fifth stage membrane module unit 20 is passed through the valve 32 In the opened state, it is sent to the second space 13 of each membrane module of the fifth-stage membrane module unit 20 through the piping 50 and the piping 91 . In addition, the water treatment device 6 may or may not include the first dilution water tank 24 and the piping 64 .

The second booster pump 80 is provided with, for example, a second inverter 82 that outputs a drive frequency corresponding to an input command signal to the second booster pump 80 . The water treatment device 6 is equipped with a control device 66; the control device 66 is connected to the first inverter 30, the second inverter 82, the first flow measuring device 34, the first 2. The flow rate measuring device 36 and the third flow rate measuring device 84 are connected. The control device 66 can also be connected to the valve 32 through a wired or wireless electrical connection.

In the water treatment method and water treatment device 6 of the present embodiment, the flow rate of the concentrated water passing through the first space of the final stage membrane module unit is measured (the first flow measurement step), and the flow rate of the concentrated water passing through the first stage membrane module unit is measured. The flow rate of the dilution water in the second space (the second flow measurement step), and measure the flow rate of the dilution water passing through the second space of the final membrane module unit (the third flow measurement step), and adjust to the first membrane module unit The flow rate of the first RO concentrated water supplied in the first space, and the flow rate of the dilution water supplied to the second space of the membrane module unit before the final stage, so that the measured value of the flow rate of the concentrated water in the final stage, the first The measured value of the flow rate of the dilution water in the stage and the measured value of the flow rate of the dilution water in the final stage become the preset target flow value (flow rate adjustment step).

For example, the control device 66 functions as a flow adjustment means: adjust the flow rate of the first RO concentrated water supplied to the first space of the first-stage membrane module unit, and the flow rate to the second space of the membrane module unit one stage before the final stage The flow rate of the dilution water supplied is such that the measured value of the flow rate of the concentrated water in the last stage membrane module unit (the example of FIG. 6 is the fifth stage membrane module unit 20) measured by the first flow rate measuring device 34 , the measured value of the flow rate of the dilution water of the first stage membrane module unit (the example of FIG. 6 is the first stage membrane module unit 12) measured by the second flow rate measuring device 36, and the measured value by the third flow rate The measured value of the flow rate of the dilution water of the last-stage membrane module unit measured by the measuring device 84 becomes a preset target flow value. The control device 66, for example, calculates the drive frequency using an arbitrary arithmetic formula, outputs a command signal corresponding to the calculated value to the first inverter 30 to control the booster pump 26, and outputs to the second inverter 82 to control the second inverter 82. 2 Booster pump 80, adjust the first RO concentrated water supplied to the first space 11 of the first stage membrane module unit (the example in FIG. The flow rate of the dilution water supplied by the second space 13 of the membrane module unit (the example of FIG. 6 is the fourth stage membrane module unit 18) so that the first flow measuring device 34, the second flow measuring device 36 and the third flow measuring device The measured value of the flow measurement device 84 becomes a preset target flow value.

As a result, in the concentration treatment of water using the semi-permeable membrane module, even if the volume of the discharged water is reduced by the reverse osmosis membrane method, and the water quality of the treated water (raw water) changes, it can still become relatively stable. processing. In addition, by using the second pressurizing pump 80 as the second pressurizing pump that inhales the dilution water of the membrane module unit of the last stage and sprays it to the membrane module unit of the previous stage, the number of stages in the membrane module unit increases, if only If the pressure required for water passage is insufficient by means of the booster pump 26, the load of the booster pump 26 can be reduced, and the insufficient pressure required for water passage can be suppressed.

In the water treatment method and water treatment device of this embodiment, the number of stages of the membrane module unit may be determined according to the target treatment water concentration and the like. For example, when it is desired to obtain treated water having a relatively concentrated concentration from treated water having a relatively low concentration, the number of stages of the membrane module unit may be increased.

The number of membrane modules of each membrane module unit can be determined according to the flow rate of the first RO permeate water, etc.

In the water treatment method and water treatment device of the present embodiment, it is preferable to have a pressurization means that pressurizes the water to be treated including the total dissolved solids to 0.1 MPa or more only in the preceding stage of the first reverse osmosis membrane treatment device 100. booster pump. That is, there is no pressurization means (pump, etc.) between the first reverse osmosis membrane treatment device 100 and the first stage membrane module unit 12. The first RO concentrated water of the reverse osmosis membrane treatment device 100 flows directly to the first-stage membrane module unit 12 . By operating the reverse osmosis membrane device and the semi-permeable membrane module with one booster pump, machine costs, power costs, and machine space can be reduced.

The first reverse osmosis membrane used in the first reverse osmosis membrane treatment device 100 should have a permeation flux of pure water in the range of 0.2-0.7m ³ /m ² /day under the conditions of effective membrane surface pressure of 1MPa and 25°C, And it has the characteristics of NaCl removal rate (under the condition of NaCl 32,000mg/L) under the standard operating pressure of 99.5% or more. The first reverse osmosis membrane is more suitable for pure water permeation flux in the range of 0.3-0.6m ³ /m ² /day under the effective pressure of the membrane surface of 1MPa and 25°C, and has a removal rate of NaCl under the standard operating pressure More than 97% of the characteristics. Under the conditions of effective membrane surface pressure of 1MPa and 25°C, if the pure water permeation flux is less than 0.2m ³ /m ² /day, there is a possibility that sufficient RO permeation water cannot be obtained; if it exceeds 0.7m ³ /m ² /day, there is a possibility that the amount of RO permeated water becomes excessive, and clogging of the membrane may occur.

The first reverse osmosis membrane treatment device 100 may also be a multistage reverse osmosis membrane treatment device. In this case, the RO concentrated water in each stage is circulated to the reverse osmosis membrane treatment device in the next stage for reverse osmosis membrane treatment, and the RO concentrated water in the final stage is sent to the first stage membrane module unit as the first RO concentrated water The first space 11 of each membrane module of 12 is conveyed and gets final product. The RO permeate water of each section can also be discharged; at least a part of the RO permeate water can also be further transported to the third reverse osmosis membrane treatment device 104 as described later, and reverse osmosis membrane treatment is performed in the third reverse osmosis membrane treatment device 104 (The third reverse osmosis membrane treatment step).

The permeation flux of the semi-permeable membrane module in the semi-permeable membrane treatment step should be in the range of 0.005m/d to 0.05m/d, more preferably 0.015m/ The range of d～0.04m/d. If the permeation flux of the semi-permeable membrane module is less than 0.005m/d under the condition of effective pressure on the membrane surface of 1MPa and 25°C, the required number of semi-permeable membrane modules may increase; if it exceeds 0.05 m/d, membrane clogging may occur.

In the water treatment method and water treatment device of the present embodiment, it is preferable to further include a decompression step: the pressure of the first RO concentrated water immediately after the first reverse osmosis membrane treatment step is above 7MPa, and in the semipermeable membrane treatment step (the first step) The first stage of membrane module unit 12) depressurizes the 1st RO concentrated water to less than 7MPa. An example of these configurations is shown in FIG. 7 .

In the water treatment device 7 of FIG. 7 , the concentrated water outlet of the first reverse osmosis membrane treatment device 100 and the first space inlet of each membrane module of the first stage membrane module unit 12 are connected through the first RO concentrated water pipe 106 They are connected in parallel via a pressure reducing valve 118 which is a pressure reducing means. Other configurations are the same as those of the water treatment device 1 in FIG. 1 . In the water treatment devices 2 to 6 of FIGS. 2 to 6 and the water treatment device 17 of FIG. 10 , the pressure reducing valve 118 may be installed in the first RO concentrated water piping 106 . With this configuration, the first RO concentrated water can be decompressed to 7 MPa, which is the upper limit of the withstand pressure of the semi-permeable membrane module, in the early stage of the semi-permeable membrane treatment step. In the water treatment device 7, there is no pressurization means (pump, etc.) between the first reverse osmosis membrane treatment device 100 and the first stage membrane module unit 12, and the first RO of the first reverse osmosis membrane treatment device 100 should be Concentrated water is decompressed by the pressure reducing valve 118 after being pressurized by the booster pump 26 , and then flows directly into the first-stage membrane module unit 12 . In addition, the water treatment device 7 may or may not include the concentrated water tank 22, the pump 28, and the piping 52. The water treatment device 7 may or may not include the first dilution water tank 24 and the piping 64 .

The pressure of the first RO concentrated water immediately after the first reverse osmosis membrane treatment step is preferably at least 7MPa, more preferably in the range of 7MPa-12MPa, and still more preferably in the range of 7MPa-10MPa. If the pressure of the first RO concentrated water immediately after the first reverse osmosis membrane treatment step is less than 7 MPa, it may not be efficiently concentrated to a high concentration, so it is preferable from the viewpoint of the pressure resistance of the reverse osmosis membrane. Make the upper limit 12MPa.

From the point of view of the pressure resistance of the semi-permeable membrane module, etc., it is better to depressurize the first RO concentrated water to less than 7MPa before the semi-permeable membrane treatment step (first-stage membrane module unit 12), and it is more preferable to decompress To the range of 3.0MPa ~ 6.9MPa.

The decompression means is not particularly limited as long as it can decompress the first RO concentrated water, and examples thereof include a decompression valve, an orifice, and the like.

The water treatment method and water treatment device of this embodiment may further include a second reverse osmosis membrane treatment step: making the dilution water flow through the second reverse osmosis membrane to obtain the second RO permeate water and the second RO concentrated water. An example of these configurations is shown in FIG. 8 .

In the water treatment device 8 shown in FIG. 8 , the outlet of the first dilution water tank 24 and the inlet of the second reverse osmosis membrane treatment device 102 are connected by a pipe 64 via a pump 120 . The concentrated water outlet of the second reverse osmosis membrane treatment device 102 is connected to the second RO concentrated water pipe 110; the permeated water outlet is connected to the second RO permeated water pipe 112. Other configurations are the same as those of the water treatment device 1 in FIG. 1 . The second reverse osmosis membrane treatment device 102 may also be installed in the water treatment devices 2 to 7 of FIGS. 2 to 7 and the water treatment device 17 of FIG. 10 . The water treatment device 8 may or may not include the concentrated water tank 22, the pump 28, and the piping 52. The water treatment device 8 may or may not be provided with the first dilution water tank 24 . In this case, the piping 62 and the piping 64 may be connected, and the pump 120 may be provided on the piping 62 or the piping 64, or may not be provided.

At least a part of the dilution water is sent to the second reverse osmosis membrane treatment device 102 through the piping 64 by the pump 120, and the reverse osmosis membrane treatment is performed in the second reverse osmosis membrane treatment device 102 to obtain the second RO concentrated water and the second RO concentrated water. Permeate water (2nd reverse osmosis membrane treatment step). The second RO permeated water obtained by the second reverse osmosis membrane treatment device 102 is discharged to the outside of the system through the second RO permeated water pipe 112 . The second RO concentrated water obtained by reverse osmosis membrane treatment can be discharged out of the system through the second RO concentrated water pipe 110 , or can be transported to the treated water tank 10 and mixed with the treated water in the treated water tank 10 . With this configuration, dilution water can be reused as the second RO permeate water.

The water treatment method and water treatment device of the present embodiment may further include a third reverse osmosis membrane treatment step: at least one of the first RO permeated water and the second RO permeated water is circulated to the third reverse osmosis membrane to obtain the third RO Permeate water and 3rd RO concentrated water. An example of these configurations is shown in FIG. 9 .

In the water treatment device 9 shown in FIG. 9 , the permeate water outlet of the first reverse osmosis membrane treatment device 100 and the inlet of the third reverse osmosis membrane treatment device 104 are connected through a first RO permeate water pipe 108 . The concentrated water outlet of the third reverse osmosis membrane treatment device 104 is connected to the third RO concentrated water pipe 114; the permeated water outlet is connected to the third RO permeated water pipe 116. Other configurations are the same as those of the water treatment device 1 in FIG. 1 . A third reverse osmosis membrane treatment device 104 may also be installed in the water treatment devices 2 to 8 of FIGS. 2 to 8 and the water treatment device 17 of FIG. 10 . In addition, the water treatment device 9 may or may not include the concentrated water tank 22, the pump 28, and the piping 52. The water treatment device 9 may or may not include the first dilution water tank 24 and the piping 64 .

At least a part of the first RO permeated water is transported to the third reverse osmosis membrane treatment device 104 through the first RO permeated water piping 108, and the reverse osmosis membrane treatment is performed in the third reverse osmosis membrane treatment device 104 to obtain the third RO concentrated water and the first RO concentrated water. 3RO permeate water (the third reverse osmosis membrane treatment step). The third RO permeated water obtained by the third reverse osmosis membrane treatment device 104 is discharged to the outside of the system through the third RO permeated water pipe 116 . The 3rd RO concentrated water obtained by the reverse osmosis membrane treatment can be discharged out of the system through the 3rd RO concentrated water pipe 114, or can be transported to the treated water tank 10, and mixed with the treated water in the treated water tank 10. With this configuration, the 3rd RO permeated water can be reused.

The water treatment device 8 in FIG. 8 may further include a reverse osmosis membrane treatment step: making the second RO permeate water flow to the reverse osmosis membrane to obtain RO permeate water and RO concentrated water.

Examples of the semipermeable membrane 15 included in the membrane module include semipermeable membranes such as reverse osmosis membranes (RO membranes), forward osmosis membranes (FO membranes), and nanofiltration membranes (NF membranes). The semipermeable membrane is preferably a reverse osmosis membrane, a forward osmosis membrane, or a nanofiltration membrane. In addition, when a reverse osmosis membrane, a forward osmosis membrane, or a nanofiltration membrane is used as the semipermeable membrane, the pressure of the target solution in the first space 11 is preferably 0.5-10.0 MPa.

The material constituting the semipermeable membrane 15 is not particularly limited, and examples thereof include cellulose-based resins such as cellulose acetate-based resins, polyether-based resins such as polyether-based resins, and polyamide-based resins. The material constituting the semipermeable membrane 15 is preferably cellulose acetate resin.

Examples of the shape of the semipermeable membrane 15 include a flat membrane, a hollow fiber membrane, a spiral membrane, and the like.

The water to be treated is not limited as long as it contains substances such as total dissolved solids (TDS). Examples include factory discharge water, brine, seawater, pharmaceutical waste liquid, and concentrated discharge water after reverse osmosis membrane treatment. wait. When the TDS (total dissolved solids) concentration of the water to be treated is, for example, 50,000 mg/L or more, more preferably 60,000 mg/L or more, and more preferably 100,000 mg/L or more, the water of this embodiment is suitable Treatment method and water treatment device. TDS (Total Dissolved Solids) contains, for example, chlorides such as sodium chloride, carbonates such as calcium carbonate and magnesium carbonate, and sulfates such as calcium sulfate and magnesium sulfate.

When the sulfate ion concentration of the first RO concentrated water is 20000 mg/L or more and the concentration of at least one of sodium ions and ammonium ions is 10000 mg/L or more, the water treatment method and water treatment device of this embodiment are suitable. The sulfate ion concentration of the first RO concentrated water is preferably 40,000 mg/L or more, more preferably in the range of 40,000-250,000 mg/L. The concentration of at least one of sodium ions and ammonium ions in the first RO concentrated water is preferably at least 20,000 mg/L, more preferably in the range of 20,000 to 100,000 mg/L.

1,2,3,4,5,6,7,8,9,17: water treatment device 10: Treated sink 11: The first space 12: The first stage membrane module unit 13: Second space 14: The second stage membrane module unit 15: Semi-permeable membrane 16: The third section membrane module unit 18: Section 4 membrane module unit 20: Section 5 membrane module unit 22: concentrated sink 24: 1st dilution tank 26: Booster pump 28,120: pump 30: 1st inverter 32,86,87: Valve 34: The first flow measuring device 36: The second flow measuring device 38,40,42,44,46,48,50,52,54,56,58,60,62,64,76,78,88,90,91,92,94: Piping 66: Control device 68: The second dilution tank 70,80: 2nd booster pump 72,82: 2nd inverter 74,84: The third flow measuring device 100: The first reverse osmosis membrane device 102: The second reverse osmosis membrane device 104: The third reverse osmosis membrane device 106: 1st RO concentrated water piping 108: 1st RO permeate water piping 110: 2nd RO concentrated water piping 112: 2nd RO permeate water piping 114: 3rd RO concentrated water piping 116: 3rd RO permeate water piping 118: Pressure reducing valve

Fig. 1 is a schematic configuration diagram showing an example of a water treatment device according to an embodiment of the present invention. Fig. 2 is a schematic configuration diagram showing another example of the water treatment device according to the embodiment of the present invention. Fig. 3 is a schematic configuration diagram showing another example of the water treatment device according to the embodiment of the present invention. Fig. 4 is a schematic configuration diagram showing another example of the water treatment device according to the embodiment of the present invention. Fig. 5 is a schematic configuration diagram showing another example of the water treatment device according to the embodiment of the present invention. Fig. 6 is a schematic configuration diagram showing another example of the water treatment device according to the embodiment of the present invention. Fig. 7 is a schematic configuration diagram showing another example of the water treatment device according to the embodiment of the present invention. Fig. 8 is a schematic configuration diagram showing another example of the water treatment device according to the embodiment of the present invention. Fig. 9 is a schematic configuration diagram showing another example of the water treatment device according to the embodiment of the present invention. Fig. 10 is a schematic configuration diagram showing another example of the water treatment device according to the embodiment of the present invention.

1: Water treatment device

10: Treated sink

11: The first space

12: The first stage membrane module unit

13: Second space

14: The second stage membrane module unit

15: Semi-permeable membrane

16: The third section membrane module unit

18: Section 4 membrane module unit

20: Section 5 membrane module unit

22: concentrated sink

24: 1st dilution tank

26: Booster pump

28: pump

30: 1st inverter

32: valve

34: The first flow measuring device

36: The second flow measuring device

38,40,42,44,46,48,50,52,54,56,58,60,62,64: Piping

66: Control device

100: The first reverse osmosis membrane device

106: 1st RO concentrated water piping

108: 1st RO permeate water piping

Claims (10)

A water treatment method, characterized in that comprising the steps of: Pressurization step, pressurizing the treated water containing total dissolved solids to above 0.1MPa; The first reverse osmosis membrane treatment step is to circulate the pressurized treated water to the first reverse osmosis membrane to obtain the first RO permeate water and the first RO concentrated water; In the semi-permeable membrane treatment step, using a semi-permeable membrane module having a first space and a second space separated by a semi-permeable membrane, the first RO concentrated water is circulated into the first space, and by the pressurization step Pressurize the first space, make the water contained in the first RO concentrated water pass through the semipermeable membrane to obtain concentrated water, and make a part of the first RO concentrated water or at least a part of the concentrated water flow into the second space circulation, to obtain dilution water; and The flow adjustment step is to measure the flow rate of the concentrated water and the flow rate of the dilution water, and adjust so that the measured values of the flow rate of the concentrated water and the measured value of the flow rate of the dilution water become preset target flow values. A water treatment method, characterized in that comprising the steps of: Pressurization step, pressurizing the treated water containing total dissolved solids to above 0.1MPa; The first reverse osmosis membrane treatment step is to circulate the pressurized treated water to the first reverse osmosis membrane to obtain the first RO permeate water and the first RO concentrated water; The semi-permeable membrane treatment step uses a semi-permeable membrane module connected in multiple sections with a first space and a second space separated by a semi-permeable membrane, so that the first RO concentrated water is sent to the first semi-permeable membrane module The first space is circulated, and the pressurization of the pressurization step pressurizes the first space, so that the water contained in the first RO concentrated water passes through the semi-permeable membrane to obtain concentrated water, and the concentrated water is further utilized in the next stage Subsequent semi-permeable membrane modules obtain concentrated water, and make a part of the first RO permeate water or at least a part of the concentrated water or at least a part of the dilution water obtained from other semi-permeable membrane modules go to the semi-permeable membrane modules of each section The second space of the group circulates to obtain dilution water; and The flow adjustment step is to measure the flow rate of the concentrated water and the flow rate of the dilution water, and adjust so that the measured values of the flow rate of the concentrated water and the measured value of the flow rate of the dilution water become preset target flow values. The water treatment method according to claim 1 or 2, wherein, the first reverse osmosis membrane has a permeation flow rate of pure water in the range of 0.2 to 0.7m ³ /m ² /day under the conditions of effective pressure on the membrane surface of 1MPa and 25°C. Quantity, and has the characteristics of NaCl removal rate (under the condition of NaCl 32,000mg/L) of 99.5% or more under the standard operating pressure. Such as the water treatment method of claim 1 or 2, wherein, The pressure of the first RO concentrated water immediately after the first reverse osmosis membrane treatment step is above 7MPa; The water treatment method further includes a decompression step: in the preceding stage of the semipermeable membrane treatment step, the first RO concentrated water is decompressed to less than 7 MPa. Such as the water treatment method of claim 1 or 2, wherein, It further includes a second reverse osmosis membrane treatment step; the dilution water is circulated to the second reverse osmosis membrane to obtain the second RO permeate water and the second RO concentrated water. A water treatment device is characterized in that comprising: Pressurization means to pressurize the treated water containing total dissolved solids to above 0.1MPa; The first reverse osmosis membrane treatment means circulates the pressurized treated water to the first reverse osmosis membrane to obtain the first RO permeated water and the first RO concentrated water; The semipermeable membrane treatment means utilizes a semipermeable membrane module having a first space and a second space separated by a semipermeable membrane, so that the first RO concentrated water flows into the first space, and is performed by the pressurization means pressurize the first space, make the water contained in the first RO concentrated water pass through the semipermeable membrane to obtain concentrated water, and make a part of the first RO concentrated water or at least a part of the concentrated water go to the first RO concentrated water. The two spaces circulate to obtain dilution water; and The flow rate adjustment means measures the flow rate of the concentrated water and the flow rate of the dilution water, and adjusts the measured values of the flow rate of the concentrated water and the measured value of the flow rate of the dilution water to a preset target flow value. A water treatment device is characterized in that comprising: Pressurization means to pressurize the treated water containing total dissolved solids to above 0.1MPa; The first reverse osmosis membrane treatment means circulates the pressurized treated water to the first reverse osmosis membrane to obtain the first RO permeated water and the first RO concentrated water; The semi-permeable membrane treatment method uses a semi-permeable membrane module connected in multiple sections with a first space and a second space separated by a semi-permeable membrane, so that the first RO concentrated water flows to the first semi-permeable membrane module The first space is circulated, and the first space is pressurized by the pressurization by the pressurization means, so that the water contained in the first RO concentrated water passes through the semi-permeable membrane to obtain concentrated water, and the concentrated water is further utilized. The semi-permeable membrane module after the next stage obtains concentrated water, and makes a part of the first RO permeate water or at least a part of the concentrated water or at least a part of the dilution water obtained from other semi-permeable membrane modules semi-permeable to each stage The second space of the membrane module circulates to obtain dilution water; and The flow rate adjustment means measures the flow rate of the concentrated water and the flow rate of the dilution water, and adjusts the measured values of the flow rate of the concentrated water and the measured value of the flow rate of the dilution water to a preset target flow value. The water treatment device according to claim 6 or 7, wherein the first reverse osmosis membrane has a permeation flow rate of pure water in the range of 0.2 to 0.7m ³ /m ² /day under the conditions of effective membrane surface pressure of 1MPa and 25°C. amount, and has the characteristics of NaCl removal rate (under the condition of NaCl 32,000mg/L) under the standard operating pressure of 99.5% or more. Such as the water treatment device of claim 6 or 7, wherein, The pressure of the first RO concentrated water immediately after the first reverse osmosis membrane treatment means is above 7MPa; The water treatment device further includes decompression means for decompressing the first RO concentrated water to less than 7 MPa at the front stage of the semipermeable membrane treatment means. Such as the water treatment device of claim 6 or 7, wherein, It further includes a second reverse osmosis membrane treatment means for passing the dilution water to the second reverse osmosis membrane to obtain the second RO permeate water and the second RO concentrated water.

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