CN115010212B - Water treatment method and water treatment device - Google Patents
Water treatment method and water treatment device Download PDFInfo
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- CN115010212B CN115010212B CN202210175986.0A CN202210175986A CN115010212B CN 115010212 B CN115010212 B CN 115010212B CN 202210175986 A CN202210175986 A CN 202210175986A CN 115010212 B CN115010212 B CN 115010212B
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 631
- 238000000034 method Methods 0.000 title claims abstract description 56
- 239000012528 membrane Substances 0.000 claims abstract description 685
- 238000001223 reverse osmosis Methods 0.000 claims abstract description 133
- 238000010790 dilution Methods 0.000 claims abstract description 125
- 239000012895 dilution Substances 0.000 claims abstract description 125
- 239000012141 concentrate Substances 0.000 claims abstract description 108
- 239000012466 permeate Substances 0.000 claims abstract description 77
- 239000007787 solid Substances 0.000 claims abstract description 23
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 22
- 230000004907 flux Effects 0.000 claims description 14
- 239000003085 diluting agent Substances 0.000 claims description 11
- 239000011780 sodium chloride Substances 0.000 claims description 11
- 238000005259 measurement Methods 0.000 description 65
- 238000010586 diagram Methods 0.000 description 10
- -1 sulfuric acid ions Chemical class 0.000 description 9
- 238000006073 displacement reaction Methods 0.000 description 6
- 238000011084 recovery Methods 0.000 description 6
- 239000007788 liquid Substances 0.000 description 4
- 239000011347 resin Substances 0.000 description 4
- 229920005989 resin Polymers 0.000 description 4
- 229910001415 sodium ion Inorganic materials 0.000 description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N sulfuric acid Substances OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- 230000003247 decreasing effect Effects 0.000 description 3
- 238000001704 evaporation Methods 0.000 description 3
- 230000008020 evaporation Effects 0.000 description 3
- 238000009292 forward osmosis Methods 0.000 description 3
- 238000001728 nano-filtration Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 description 2
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 2
- 229920002301 cellulose acetate Polymers 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000003204 osmotic effect Effects 0.000 description 2
- 238000011144 upstream manufacturing Methods 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 239000004695 Polyether sulfone Substances 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 239000012267 brine Substances 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 239000012461 cellulose resin Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000002894 chemical waste Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000008236 heating water Substances 0.000 description 1
- 239000012510 hollow fiber Substances 0.000 description 1
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 description 1
- 239000001095 magnesium carbonate Substances 0.000 description 1
- 229910000021 magnesium carbonate Inorganic materials 0.000 description 1
- 229910052943 magnesium sulfate Inorganic materials 0.000 description 1
- 235000019341 magnesium sulphate Nutrition 0.000 description 1
- 229920002492 poly(sulfone) Polymers 0.000 description 1
- 229920006122 polyamide resin Polymers 0.000 description 1
- 229920006393 polyether sulfone Polymers 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000013535 sea water Substances 0.000 description 1
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/441—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by reverse osmosis
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/442—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by nanofiltration
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/445—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by forward osmosis
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2301/00—General aspects of water treatment
- C02F2301/06—Pressure conditions
- C02F2301/066—Overpressure, high pressure
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A20/00—Water conservation; Efficient water supply; Efficient water use
- Y02A20/124—Water desalination
- Y02A20/131—Reverse-osmosis
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Organic Chemistry (AREA)
- Nanotechnology (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
The water concentration treatment using the semipermeable membrane module can perform stable treatment even when the quality of the water to be treated varies. The water treatment method comprises the following steps: a pressurizing step of pressurizing the water to be treated containing the total dissolved solid components to 0.1MPa or more; a first reverse osmosis membrane treatment step of introducing the pressurized water to be treated into a first reverse osmosis membrane to obtain first RO permeate water and first RO concentrate water; a semipermeable membrane treatment step of introducing first RO concentrate into a first space using a semipermeable membrane module having first and second spaces partitioned by a semipermeable membrane, pressurizing the first space by pressurization to allow water contained in the first RO concentrate to permeate the semipermeable membrane to obtain concentrate, and introducing a part of the first RO concentrate or at least a part of the concentrate into a second space to obtain dilution water; and a flow rate adjustment step of measuring the flow rate of the concentrated water and the flow rate of the diluted water, and adjusting the flow rate of the concentrated water and the flow rate of the diluted water so that the measured values of the flow rates become target flow rate values set in advance.
Description
Technical Field
The present invention relates to a water treatment method and a water treatment apparatus for performing concentration treatment of water containing Total Dissolved Solids (TDS) and the like.
Background
In recent years, treatment for minimizing the amount of water discharged from factories and the like has been performed, and a method of concentrating the water discharged by reverse osmosis membrane and the like, and recovering permeate water to reduce the volume of the water discharged has been adopted. There is a trend toward as high a water recovery rate as possible, and there is also an increase in the number of factories and the like that recover substantially the entire amount of water by evaporation concentration and the like, and discharge the total dissolved solid components and the like as solid ZLD (Zero Liquid Discharge ).
Since a method of heating water such as evaporation concentration requires a large amount of energy consumption and increases the cost, a method of concentrating the drain water to a high concentration by a method of not heating as much as possible is desired. The reverse osmosis membrane method consumes less energy than the evaporation concentration method, but the concentration becomes insufficient due to the influence of osmotic pressure, and the volume may not be reduced to the target water amount.
Patent document 1 describes the following method: the water is concentrated by flowing raw water or concentrated water thereof through a first space and a second space partitioned by a semipermeable membrane of a multistage semipermeable membrane module, and pressurizing the first space. The method of patent document 1 is a method of concentrating to a high concentration with less pressurization power, that is, with less energy, than a general concentration method using a reverse osmosis membrane by reducing a concentration difference (osmotic pressure difference) between a first space and a second space of a semipermeable membrane module.
The concentration method described in patent document 1 requires not only the first space of the semipermeable membrane module but also the flow rate and concentration of the second space, and therefore, as compared with the reverse osmosis membrane method, the water balance is easily broken due to the fluctuation of the quality of raw water (water to be treated), and it is likely that the capacity reduction of the water discharge amount is difficult to be stably performed. In addition, when such a method of concentrating to a high concentration is used, there is a possibility that the quality of the recovered water is deteriorated to be unsuitable for the recovered water.
Prior art literature
Patent literature
Patent document 1: japanese patent laid-open publication No. 2018-069198
Disclosure of Invention
(problem to be solved by the invention)
The purpose of the present invention is to provide a water treatment method and a water treatment apparatus, which can perform stable treatment even when there is a fluctuation in the quality of water to be treated (raw water) in the concentration treatment of water using a semipermeable membrane module.
(means for solving the problems)
The invention is a water treatment method comprising: a pressurizing step of pressurizing the water to be treated containing the total dissolved solid components to 0.1MPa or more; a first reverse osmosis membrane treatment step of introducing the pressurized water to be treated into a first reverse osmosis membrane to obtain first RO permeate water and first RO concentrate water; a semipermeable membrane treatment step of introducing the first RO concentrate into a first space and a second space separated by a semipermeable membrane using a semipermeable membrane module, pressurizing the first space by pressurization in the pressurization step to allow water contained in the first RO concentrate to permeate the semipermeable membrane to obtain concentrate, and introducing a part of the first RO concentrate or at least a part of the concentrate into the second space to obtain diluent; and a flow rate adjustment step of measuring the flow rate of the concentrated water and the flow rate of the diluted water, and adjusting the flow rate measurement value of the concentrated water and the flow rate measurement value of the diluted water to a target flow rate value set in advance.
The invention is a water treatment method comprising: a pressurizing step of pressurizing the water to be treated containing the total dissolved solid components to 0.1MPa or more; a first reverse osmosis membrane treatment step of introducing the pressurized water to be treated into a first reverse osmosis membrane to obtain first RO permeate water and first RO concentrate water; a semipermeable membrane treatment step of introducing the first RO concentrate into a first space of a first-stage semipermeable membrane module using a semipermeable membrane module having a first space and a second space separated by a semipermeable membrane, pressurizing the first space by pressurizing the first space to permeate the semipermeable membrane to obtain concentrate, further using a semipermeable membrane module of a subsequent stage to the concentrate to obtain concentrate, and introducing a part of the first RO permeate or at least a part of the concentrate or at least a part of the diluent obtained from another semipermeable membrane module into a second space of a semipermeable membrane module of each stage to obtain diluent; and a flow rate adjustment step of measuring the flow rate of the concentrated water and the flow rate of the diluted water, and adjusting the flow rate measurement value of the concentrated water and the flow rate measurement value of the diluted water to a target flow rate value set in advance.
In the water treatment method, the first reverse osmosis membrane preferably has a membrane surface effective pressure of 1MPa and 25 ℃ of 0.2 to 0.7m 3 /m 2 Pure water permeate flux in the range of/day and has NaC at standard operating pressureThe removal rate (under the condition of 32,000mg/L NaCl) is 99.5% or more.
In the above water treatment method, it is preferable that the permeation flux of the semipermeable membrane module in the semipermeable membrane treatment step is set to a range of 0.005m/d to 0.05m/d under conditions of a membrane surface effective pressure of 1MPa and 25 ℃.
In the water treatment method, it is preferable that the pressure of the first RO concentrated water immediately after the first reverse osmosis membrane step is 7MPa or more, and the water treatment method further includes a depressurizing step of depressurizing the first RO concentrated water to less than 7MPa at a stage preceding the semipermeable membrane treatment step.
In the water treatment method, it is preferable that the method further comprises: and a second reverse osmosis membrane treatment step in which the diluted water is passed to a second reverse osmosis membrane to obtain second RO permeate and second RO concentrate.
In the water treatment method, it is preferable that the method further comprises: and a third reverse osmosis membrane treatment step in which at least one of the first RO permeate and the second RO permeate is passed through a third reverse osmosis membrane to obtain third RO permeate and third RO concentrate.
In the water treatment method, it is preferable that the concentration of sulfuric acid ions in the first RO concentrated water is 20000mg/L or more and the concentration of at least one of sodium ions and ammonium ions is 10000mg/L or more.
The present invention is a water treatment device, comprising: a pressurizing unit for pressurizing the water to be treated containing the total dissolved solid components to 0.1MPa or more; a first reverse osmosis membrane treatment unit that introduces the pressurized water to be treated into a first reverse osmosis membrane to obtain first RO permeate water and first RO concentrate water; a semipermeable membrane treatment unit that uses a semipermeable membrane module having a first space and a second space separated by a semipermeable membrane, that introduces the first RO concentrated water into the first space, that pressurizes the first space based on pressurization by the pressurizing unit to permeate the water contained in the first RO concentrated water through the semipermeable membrane to obtain concentrated water, and that introduces a part of the first RO concentrated water or at least a part of the concentrated water into the second space to obtain diluted water; and a flow rate adjustment means for measuring the flow rate of the concentrated water and the flow rate of the diluted water, and adjusting the flow rate measurement value of the concentrated water and the flow rate measurement value of the diluted water to target flow rate values set in advance.
The present invention is a water treatment device, comprising: a pressurizing unit for pressurizing the water to be treated containing the total dissolved solid components to 0.1MPa or more; a first reverse osmosis membrane treatment unit that introduces the pressurized water to be treated into a first reverse osmosis membrane to obtain first RO permeate water and first RO concentrate water; a semipermeable membrane treatment unit that uses a semipermeable membrane module having a first space and a second space separated by a semipermeable membrane and connected in multiple stages, that passes the first RO concentrate into the first space of the first stage semipermeable membrane module, that pressurizes the first space based on pressurization by the pressurizing unit to permeate the water contained in the first RO concentrate through the semipermeable membrane to obtain concentrate, that further uses the next and subsequent semipermeable membrane modules to obtain concentrate, and that passes a part of the first RO permeate or at least a part of the concentrate or at least a part of the diluent obtained from the other semipermeable membrane modules to the second space of each stage semipermeable membrane module to obtain diluent; and a flow rate adjustment means for measuring the flow rate of the concentrated water and the flow rate of the diluted water, and adjusting the flow rate measurement value of the concentrated water and the flow rate measurement value of the diluted water to target flow rate values set in advance.
In the water treatment apparatus, the first reverse osmosis membrane preferably has a membrane surface effective pressure of 1MPa and a temperature of 25 ℃ of 0.2 to 0.7m 3 /m 2 Pure water permeation flux in the range of/day, and has a characteristic that the NaCl removal rate (at 32,000mg/L NaCl) at standard operating pressure is 99.5% or more.
The water treatment apparatus preferably further comprises a permeation flux adjustment means for adjusting the permeation flux of the semipermeable membrane module in the semipermeable membrane treatment means so that the permeation flux is in a range of 0.005m/d to 0.05m/d under conditions of a membrane surface effective pressure of 1MPa and 25 ℃.
In the water treatment apparatus, it is preferable that the pressure of the first RO concentrated water immediately after the first reverse osmosis membrane unit is 7MPa or more, and a pressure reducing unit that reduces the pressure of the first RO concentrated water to less than 7MPa is further provided at a stage preceding the semipermeable membrane treatment unit.
The water treatment apparatus preferably further includes: and a second reverse osmosis membrane treatment unit that passes the diluted water to a second reverse osmosis membrane to obtain second RO permeate and second RO concentrate.
The water treatment apparatus preferably further includes: and a third reverse osmosis membrane treatment unit that passes at least one of the first RO-permeate water and the second RO-permeate water through a third reverse osmosis membrane to obtain third RO-permeate water and third RO concentrate water.
In the water treatment apparatus, the concentration of sulfuric acid ions in the first RO concentrated water is preferably 20000mg/L or more, and the concentration of at least one of sodium ions and ammonium ions is preferably 10000mg/L or more.
(effects of the invention)
According to the present invention, it is possible to provide a water treatment method and a water treatment apparatus capable of performing stable treatment even when there is a fluctuation in the quality of water to be treated (raw water) in the concentration treatment of water using a semipermeable membrane module.
Drawings
Fig. 1 is a schematic configuration diagram illustrating an example of a water treatment apparatus according to an embodiment of the present invention.
Fig. 2 is a schematic configuration diagram illustrating another example of the water treatment apparatus according to the embodiment of the present invention.
Fig. 3 is a schematic configuration diagram illustrating another example of the water treatment apparatus according to the embodiment of the present invention.
Fig. 4 is a schematic configuration diagram illustrating another example of the water treatment apparatus according to the embodiment of the present invention.
Fig. 5 is a schematic configuration diagram illustrating another example of the water treatment apparatus according to the embodiment of the present invention.
Fig. 6 is a schematic configuration diagram illustrating another example of the water treatment apparatus according to the embodiment of the present invention.
Fig. 7 is a schematic configuration diagram illustrating another example of the water treatment apparatus according to the embodiment of the present invention.
Fig. 8 is a schematic configuration diagram illustrating another example of the water treatment apparatus according to the embodiment of the present invention.
Fig. 9 is a schematic configuration diagram illustrating another example of the water treatment apparatus according to the embodiment of the present invention.
Fig. 10 is a schematic configuration diagram illustrating another example of the water treatment apparatus according to the embodiment of the present invention.
Detailed Description
Embodiments of the present invention are described below. The present embodiment is an example of the implementation of the present invention, and the present invention is not limited to the present embodiment.
Fig. 1 schematically shows an example of a water treatment apparatus according to an embodiment of the present invention, and a configuration thereof will be described.
The water treatment apparatus 1 shown in fig. 1 includes a pressurizing pump 26 as a pressurizing means for pressurizing water to be treated containing total dissolved solid components to 0.1MPa or more, a first reverse osmosis membrane treatment apparatus 100 as a first reverse osmosis membrane treatment means for pressurizing the water to be treated after pressurization by a first reverse osmosis membrane to obtain first RO permeate and first RO concentrate, and for example, a first-stage membrane module unit 12, a second-stage membrane module unit 14, a third-stage membrane module unit 16, a fourth-stage membrane module unit 18, and a fifth-stage membrane module unit 20 as semipermeable membrane treatment means for pressurizing the water to be treated by the pressurizing pump 26 to obtain first RO concentrate by pressurizing the first space, and for introducing at least a part of the first RO concentrate or at least a part of the water to the second space to obtain dilute concentrate by using a single-stage or multistage semipermeable membrane module having a first space (concentrating side) and a second space (permeate side) partitioned by semipermeable membranes. The water treatment apparatus 1 includes a pressurizing pump as pressurizing means for pressurizing the water to be treated containing the total dissolved solid content to 0.1MPa or more only in the stage preceding the first reverse osmosis membrane treatment apparatus 100.
The first-stage membrane module unit 12 includes, for example, 6 membrane modules connected in parallel, the second-stage membrane module unit 14 includes, for example, 5 membrane modules connected in parallel, the third-stage membrane module unit 16 includes, for example, 4 membrane modules connected in parallel, the fourth-stage membrane module unit 18 includes, for example, 3 membrane modules connected in parallel, and the fifth-stage membrane module unit 20 includes, for example, 3 membrane modules connected in parallel. Each membrane module is provided with a first space 11 and a second space 13 separated by a semi-permeable membrane 15. The water treatment apparatus 1 may further include: a water tank 10 for storing water to be treated; a concentrate tank 22 that stores concentrate water from the membrane module unit of the final stage (concentrate water from the membrane module unit 20 of the fifth stage in the example of fig. 1); and a first dilution water tank 24 that stores dilution water from the first-stage membrane module unit (dilution water from the first-stage membrane module unit 12 in the example of fig. 1).
In the water treatment apparatus 1 of fig. 1, a pipe 38 is connected to a water inlet of the water tank 10 to be treated. The outlet of the water tank 10 to be treated and the inlet of the first reverse osmosis membrane treatment apparatus 100 are connected to each other through a pipe 40 by a booster pump 26. The concentrate water outlet of the first reverse osmosis membrane treatment apparatus 100 and the first space inlet of each membrane module of the first-stage membrane module unit 12 are connected in parallel by a first RO concentrate water pipe 106. A first RO permeate piping 108 is connected to the permeate outlet of the first reverse osmosis membrane treatment apparatus 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 first space outlet of each membrane module of the second-stage membrane module unit 14 and the first space inlet of each membrane module of the third-stage membrane module unit 16 are connected in parallel by piping 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 first space outlet of each membrane module of the fifth-stage membrane module unit 20 and the inlet of the concentrate tank 22 are connected via a valve 32 through a pipe 50. A pipe 52 is connected to the outlet of the concentrate tank 22 via a pump 28. 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 are connected in parallel by piping 54. The second space outlet of each membrane module of the fourth-stage membrane module unit 18 and the second space inlet of each membrane module of the third-stage membrane module unit 16 are connected in parallel by piping 56. The second space outlet of each membrane module of the third stage membrane module unit 16 and the second space inlet of each membrane module of the second stage membrane module unit 14 are connected in parallel by piping 58. The second space outlet of each membrane module of the second-stage membrane module unit 14 and the second space inlet of each membrane module of the first-stage membrane module unit 12 are connected in parallel by piping 60. The second space outlet 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. The water treatment apparatus 1 may or may not include the concentrate tank 22, the pump 28, and the pipe 52. The water treatment apparatus 1 may or may not include the first dilution water tank 24 and the pipe 64.
The booster pump 26 is provided at a stage preceding the first reverse osmosis membrane treatment apparatus 100, and is driven at a rotational speed corresponding to the inputted driving frequency, for example, to suck in the water to be treated and discharge the water to the first reverse osmosis membrane treatment apparatus 100. The pressure pump 26 is provided with, for example, a first inverter 30 that outputs a driving frequency corresponding to an inputted command signal to the pressure pump 26. A first flow rate measuring device 34 is provided between the valve 32 in the pipe 50 and the inlet of the concentrate tank 22, and is a first flow rate measuring means for measuring the flow rate of the concentrate water passing through the first space of the final-stage membrane module unit (in the example of fig. 1, the fifth-stage membrane module unit 20). The piping 62 is provided with the second flow rate measuring device 36 as a second flow rate measuring means for measuring the flow rate of the dilution water passing through the second space of the first-stage membrane module unit (in the example of fig. 1, the first-stage membrane module unit 12). The valve 32 is provided at a stage subsequent to the final stage membrane module unit (in the example of fig. 1, the fifth stage membrane module unit 20), and is, for example, a proportional control valve for adjusting the opening degree based on the measured values of the first flow rate measuring device 34 and the second flow rate measuring device 36. The water treatment apparatus 1 includes a control device 66, and the control device 66 is connected to the first inverter 30, the first flow rate measurement device 34, and the second flow rate measurement device 36 by wired or wireless electrical connection or the like. The control device 66 may also be connected to the valve 32 by a wired or wireless electrical connection or the like.
The water treatment method according to the present embodiment and the operation of the water treatment apparatus 1 will be described.
The water treatment apparatus 1 is as follows: using, for example, a multistage membrane module having a first space 11 and a second space 13 partitioned by a semipermeable membrane 15, a first RO concentrate obtained by reverse osmosis membrane treatment of a first reverse osmosis membrane treatment apparatus 100 for reverse osmosis membrane treatment of water to be treated containing total dissolved solid components is introduced into the first space 11 of the multistage membrane module in series, and concentrate of a preceding stage membrane module unit (in the example of FIG. 1, a fourth stage membrane module unit 18) is distributed to the first space 11 and the second space 13 of the final stage membrane module unit (in the example of FIG. 1) by pressurizing the first space 11 so that water contained in the first space 11 is permeated into the second space 13 to concentrate the water. That is, in the water treatment apparatus 1, the first RO concentrated water is concentrated using the semipermeable membrane 15, and the concentrated water is further concentrated using the semipermeable membrane 15 of the next stage. The first RO concentrate is supplied to the first space 11 of the first-stage membrane module unit (in the example of fig. 1, the first-stage membrane module unit 12), and the concentrate is supplied to both the first space 11 and the second space 13 of the final-stage membrane module unit (in the example of fig. 1, the fourth-stage membrane module unit 18). Then, the dilution water having passed through the second space 13 of the membrane module of the final stage is supplied to the second space 13 of the membrane module upstream thereof, and the first space 11 of the membrane module of each stage is pressurized to allow water contained in the first space 11 to permeate into the second space 13.
Specifically, in the water treatment apparatus 1, the water to be treated containing the total dissolved solid content is stored in the water tank 10 to be treated through the pipe 38 as needed, pressurized to 0.1MPa or more by the pressurizing pump 26 from the water tank 10 to be treated (pressurizing step), and the liquid is sent to the first reverse osmosis membrane treatment apparatus 100 through the pipe 40. In the first reverse osmosis membrane treatment apparatus 100, the pressurized water to be treated is passed to a first reverse osmosis membrane to obtain first RO permeate and first RO concentrate (first reverse osmosis membrane treatment step). The first RO permeate is discharged through the first RO permeate pipe 108. At least a part of the first RO permeate may be further sent to the third reverse osmosis membrane treatment apparatus 104 as described later, and reverse osmosis membrane treatment may be performed in the third reverse osmosis membrane treatment apparatus 104 (third reverse osmosis membrane treatment step).
The first RO concentrate is fed to the first space 11 of each membrane module of the first stage membrane module unit 12 through the first RO concentrate pipe 106. 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, the second space 13 of the third-stage membrane module unit 16, and the second space 13 of the second-stage membrane module unit 14 is fed to the second spaces 13 of the respective membrane modules of the first-stage membrane module unit 12 through the piping 60. In each membrane module of the first-stage membrane module unit 12, the first space 11 is pressurized by pressurization of the pressurizing pump 26, so that water contained in the first space 11 is permeated into the second space 13 (concentration step (first stage)).
The concentrated water of the first-stage membrane module unit 12 is fed to the first space 11 of each membrane module of the second-stage membrane module unit 14 through the piping 42. On the other hand, the dilution water returned from the fifth-stage membrane module unit 20 of the final stage, which will be described later, through the second space 13 of the fourth-stage membrane module unit 18 and the second space 13 of the third-stage membrane module unit 16 is sent to the second spaces 13 of the respective membrane modules of the second-stage membrane module unit 14 through the piping 58. In each membrane module of the second-stage membrane module unit 14, the first space 11 is pressurized, and water contained in the first space 11 is permeated into the second space 13 (concentration step (second stage)) as in the first stage.
The concentrated water of the second-stage membrane module unit 14 is fed to the first space 11 of each membrane module of the third-stage membrane module unit 16 through the piping 44. On the other hand, the dilution water returned from the fifth-stage membrane module unit 20 of the final stage, which will be described later, through the second space 13 of the fourth-stage membrane module unit 18 is sent to the second space 13 of each membrane module of the third-stage membrane module unit 16 through the pipe 56. In the respective membrane modules of the third-stage membrane module unit 16, the first space 11 is pressurized and water contained in the first space 11 is permeated into the second space 13 (concentration step (third stage)) in the same manner as in the first and second stages.
The concentrated water of the third-stage membrane module unit 16 is fed to the first space 11 of each membrane module of the fourth-stage membrane module unit 18 through the piping 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 piping 54. In the respective membrane modules of the fourth-stage membrane module unit 18, the first space 11 is pressurized and water contained in the first space 11 is permeated into the second space 13 (concentration step (fourth stage)) in the same manner as the first, second and third stages.
The concentrated water in the fourth-stage membrane module unit 18 is distributed and fed to the first space 11 and the second space 13 of each membrane module in the fifth-stage membrane module unit 20 in the final stage through the piping 48. In the fifth-stage membrane module unit 20, the first space 11 is pressurized and water contained in the first space 11 is permeated into the second space 13 (concentration step (fifth stage)) in the same manner as in the first to fourth stages. Here, the pressurizing pump 26, the piping 48, and the like function as a supply means for supplying the concentrate of the preceding stage to both the first space and the second space of the semipermeable membrane module of the final stage.
The concentrate of the fifth-stage membrane module unit 20 is fed to the concentrate tank 22 and stored as needed through the pipe 50 with the valve 32 opened. At least a part of the concentrated water is discharged as treated water from the concentrated water tank 22 to the outside of the system through the pipe 52 by the pump 28. At least a part of the concentrated water may be fed to the water tank 10 to be treated, and mixed with the water to be treated in the water tank 10 to be treated.
The dilution water of the fifth-stage membrane module unit 20 is sent to the second space 13 of each membrane module of the fourth-stage membrane module unit 18 through the piping 54. As described above, in each membrane module of the fourth-stage membrane module unit 18, the first space 11 is pressurized, and water contained in the first space 11 is permeated into the second space 13 (concentration step (fourth stage)).
The dilution water of the fourth-stage membrane module unit 18 is sent to the second space 13 of each membrane module of the third-stage membrane module unit 16 through the piping 56. As described above, in each membrane module of the third-stage membrane module unit 16, the first space 11 is pressurized, and water contained in the first space 11 is permeated into the second space 13 (concentration step (third stage)).
The dilution water of the third-stage membrane module unit 16 is sent to the second space 13 of each membrane module of the second-stage membrane module unit 14 through the piping 58. As described above, in each membrane module of the second-stage membrane module unit 14, the first space 11 is pressurized, and water contained in the first space 11 is permeated into the second space 13 (concentration step (second stage)).
The dilution water of the second-stage membrane module unit 14 is sent to the second space 13 of each membrane module of the first-stage membrane module unit 12 through the piping 60. As described above, in each membrane module of the first-stage membrane module unit 12, the first space 11 is pressurized, and water contained in the first space 11 is permeated into the second space 13 (concentration step (first stage)).
The dilution water of the first-stage membrane module unit 12 is fed to the first dilution water tank 24 through a pipe 62 as needed, stored, and then discharged to the outside of the system through a pipe 64. At least a part of the dilution water may be fed to the water tank 10 to be treated, and mixed with the water to be treated in the water tank 10 to be treated. At least a part of the dilution water may be further fed to the second reverse osmosis membrane treatment apparatus 102 as described later, and the second reverse osmosis membrane treatment apparatus 102 may perform reverse osmosis membrane treatment (second reverse osmosis membrane treatment step).
The treatment is performed as described above, and the treated water (final-stage concentrated water) in which the substances such as the total dissolved solids and the like are concentrated and the dilution water are obtained from the treated water containing the total dissolved solids and the like as the treatment target, thereby reducing the volume of the treated water.
In the water treatment method and the water treatment apparatus 1 according to the present embodiment, the flow rate of the concentrated water passing through the first space of the semipermeable membrane module of the final stage (first flow rate measurement step) and the flow rate of the diluted water passing through the second space of the semipermeable membrane module of the first stage (second flow rate measurement step) are measured, and the flow rate of the first RO concentrated water supplied to the first space of the semipermeable membrane module of the first stage is adjusted so that the measured value of the flow rate of the concentrated water of the final stage and the measured value of the flow rate of the diluted water of the first stage become the target flow rate value set in advance (flow rate adjustment step).
For example, the control device 66 functions as a flow rate adjustment means for adjusting the flow rate of the first RO concentrated water supplied to the first space of the semipermeable membrane module of the first stage so that the measured value of the flow rate of the concentrated water of the membrane module unit of the final stage (the fifth-stage membrane module unit 20 in the example of fig. 1) measured by the first flow rate measurement means 34 and the measured value of the flow rate of the diluent water of the membrane module unit of the first stage (the first-stage membrane module unit 12 in the example of fig. 1) measured by the second flow rate measurement means 36 become target flow rate values set in advance. The control device 66 calculates the driving frequency using an arbitrary operation formula, outputs a command signal corresponding to the calculated value to the first inverter 30 to control the booster pump 26, and adjusts the flow rate of the first RO concentrated water supplied to the first space 11 of the first-stage membrane module unit (in the example of fig. 1, the first-stage membrane module unit 12) so that the measured values of the first flow rate measuring device 34 and the second flow rate measuring device 36 become target flow rate values set in advance.
As a result, in the concentration treatment of water using the semipermeable membrane module, even when there is a variation in the quality of the water to be treated (raw water) while the displacement is reduced by the reverse osmosis membrane method, stable treatment can be performed.
Specifically, for example, the pressurizing pump 26 is started, and the valve 32 is opened fully (opening degree 100%), for example, to gradually increase the output value of the first inverter 30 attached to the pressurizing pump 26. 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, an arbitrary predetermined ratio (for example, the opening degree is set to 10% with respect to the full opening). Since the measured value of the first flow rate measuring device 34 decreases, the output of the first inverter 30 of the pressurizing pump 26 is increased until the measured value of the first flow rate 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. Thereafter, the operations of increasing the output of the first inverter 30, increasing the measurement value of the first flow rate measuring device 34, closing the valve 32, decreasing the measurement value of the first flow rate measuring device 34, and increasing the measurement value of the second flow rate measuring device 36 are repeated, and the measurement values of the first flow rate measuring device 34 and the second flow rate measuring device 36 may be adjusted to the target flow rate.
When the recovery rate of the water to be treated changes, for example, the output value of the first inverter 30 and the opening degree of the valve 32 are automatically controlled to change the flow rate of the first RO concentrated water so that the recovery rate of the water to be treated (recovery rate=second flow rate measurement value/(first flow rate measurement value+second flow rate measurement value) ×100) based on the measurement value of the first flow rate measurement device 34 and the measurement value of the second flow rate measurement device 36 becomes as constant as possible. When the flow rate of the first space measured by the first flow rate measuring device 34 is smaller than the set flow rate, the output value of the first inverter 30 may be fixed and the opening degree of the valve 32 may be increased (i.e., the valve may be opened). The opening degree of the valve 32 may be adjusted by repeating the following steps: a predetermined arbitrary ratio (for example, 10% of the opening degree with respect to the total opening) is opened, and the flow rate of the first space measured by the first flow rate measuring device 34 is observed for a predetermined time (for example, 1 minute). Alternatively, the opening degree of the valve 32 may be fixed, and the output value of the first inverter 30 may be increased to increase the flow rate of the first space.
When the flow rate of 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 reduced. However, when the pressure pump 26 reaches the output lower limit value of the guaranteed operation, the opening degree of the valve 32 is reduced (the valve is closed). The adjustment of the opening degree of the valve 32 may be repeated, for example, by: the flow rate of the first space measured by the first flow rate measuring device 34 is observed within a predetermined time (for example, 1 minute) by closing a predetermined arbitrary ratio (for example, the opening degree is set to 10% with respect to the total opening). Alternatively, the output value of the first inverter 30 may be fixed, and the opening degree of the valve 32 may be reduced to reduce the flow rate of the first space.
When the flow rate of the second space measured by the second flow rate measuring device 36 is smaller than the set flow rate, the flow rate of the first space is increased, so that the output value of the first inverter 30 may be fixed and the opening degree of the valve 32 may be reduced. Alternatively, the opening degree of the valve 32 may be fixed, and the output value of the first inverter 30 may be increased. When the flow rate of the second space measured by the second flow rate measuring device 36 is larger than the set flow rate, the flow rate of the first space is decreased, so that the output value of the first inverter 30 may be fixed and the opening degree of the valve 32 may be increased. Alternatively, the opening degree of the valve 32 may be fixed, and the output value of the first inverter 30 may be reduced.
The proportional control valve whose opening degree is adjusted based on the measured values of the first flow rate measuring device 34 and the second flow rate measuring device 36 may be provided in the piping of the first space 11, for example, in the piping 106, 42, 44, 46, 48, or may be manually adjusted, or may be automatically adjusted by the control device 66.
In addition to the first flow rate measuring device 34 that measures the flow rate of the concentrated water passing through the first space of the membrane module unit of the final stage, one or more flow rate measuring devices that measure the flow rate of the first space 11 may be provided in the piping of the first space 11, for example, in the piping 106, 42, 44, 46, 48.
In addition to the second flow rate measuring device 36 for measuring the flow rate of the dilution water passing through the second space of the first-stage membrane module unit, one or more flow rate measuring devices for measuring the flow rate of the second space 13 may be provided in the piping of the second space 13, for example, in the piping 54, 56, 58, 60.
In the water treatment apparatus 1, the flow rate of the dilution water passing through the second space of the membrane module unit of the final stage may be further measured, and the flow rate of the first RO concentrated water supplied to the first space of the membrane module unit of the first stage and the flow rate of the dilution water supplied to the second space of the preceding stage of the final stage may be adjusted so that the measured value of the flow rate of the concentrated water of the final stage, the measured value of the flow rate of the dilution water of the first stage, and the measured value of the flow rate of the dilution water of the final stage become target flow rate values set in advance. Fig. 2 shows a water treatment apparatus having such a structure.
The water treatment apparatus 2 shown in fig. 2 further includes a second dilution water tank 68 for storing dilution water from the membrane module unit of the final stage (in the example of fig. 2, dilution water from the membrane module unit 20 of the fifth stage). In the water treatment apparatus 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 and the second space inlet of each membrane module of the fourth-stage membrane module unit 18 are connected in parallel by a piping 78 via the second booster pump 70. The water treatment apparatus 2 may or may not include the concentrate tank 22, the pump 28, and the pipe 52. The water treatment apparatus 2 may or may not include the first dilution water tank 24 and the pipe 64.
The dilution water of the fifth-stage membrane module unit 20 is supplied to the second dilution water tank 68 through the pipe 76 and stored, and then is supplied from the second dilution water tank 68 to the second space 13 of each membrane module of the fourth-stage membrane module unit 18 through the pipe 78 by the second pressurizing pump 70. As described above, in each membrane module of the fourth-stage membrane module unit 18, the first space 11 is pressurized, and water contained in the first space 11 is permeated into the second space 13 (concentration step (fourth stage)).
The piping 76 is provided with a third flow rate measuring device 74 as a third flow rate measuring means for measuring the flow rate of the dilution water passing through the second space of the final-stage membrane module unit (in the example of fig. 2, the fifth-stage membrane module unit 20). The second pressurizing pump 70 is provided at the subsequent stage of the final-stage membrane module unit (fifth-stage membrane module unit 20 in the example of fig. 2), and is, for example, a second pressurizing pump that is driven at a rotational speed corresponding to the inputted driving frequency, sucks in the dilution water of the final-stage membrane module unit (dilution water of the fifth-stage membrane module unit 20 in the example of fig. 2), and ejects the dilution water toward the front-stage membrane module unit (fourth-stage membrane module unit 18 in the example of fig. 2). The second booster pump 70 is provided with, for example, a second inverter 72 that outputs a driving frequency corresponding to the inputted command signal to the second booster pump 70. The installation locations of the second dilution water tank 68, the second pressurizing pump 70, and the flow rate measuring device 74 are not limited to the positions shown in fig. 2, and may be any of the pipes for the dilution water in the middle, for example, any of the pipes 56, 58, and 60. The water treatment apparatus 2 includes a control device 66, and the control device 66 is connected to the first inverter 30, the second inverter 72, the first flow rate measuring device 34, the second flow rate measuring device 36, and the third flow rate measuring device 74 by wired or wireless electrical connection or the like. The control device 66 may also be connected to the valve 32 by a wired or wireless electrical connection or the like.
In the water treatment method and the water treatment apparatus 2 according to the present embodiment, the flow rate of the concentrated water passing through the first space of the membrane module unit of the final stage (first flow rate measurement step), the flow rate of the diluted water passing through the second space of the membrane module unit of the first stage (second flow rate measurement step), and the flow rate of the diluted water passing through the second space of the membrane module unit of the final stage (third flow rate measurement step) are measured, and the flow rates of the first RO concentrated water supplied to the first space of the membrane module unit of the first stage and the diluted water supplied to the second space of the membrane module unit of the preceding stage of the final stage are adjusted so that the measured value of the flow rate of the concentrated water of the final stage, the measured value of the flow rate of the diluted water of the first stage, and the measured value of the flow rate of the diluted water of the final stage become target flow rate values set in advance (flow rate adjustment step).
For example, the control device 66 functions as a flow rate adjustment means for adjusting 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 the dilution water supplied to the second space of the final-stage membrane module unit such that the measurement value of the flow rate of the concentrated water in the final-stage membrane module unit (in the example of fig. 2, the fifth-stage membrane module unit 20) measured by the first flow rate measurement means 34, the measurement value of the flow rate of the dilution water in the first-stage membrane module unit (in the example of fig. 2, the first-stage membrane module unit 12) measured by the second flow rate measurement means 36, and the measurement value of the flow rate of the dilution water in the final-stage membrane module unit measured by the third flow rate measurement means 74 are set to target flow rate values set in advance. The control device 66 calculates the driving frequency by using an arbitrary operation formula, outputs a command signal corresponding to the calculated value to the first inverter 30 to control the booster pump 26, outputs the command signal to the second inverter 72 to control the second booster pump 70, and adjusts the flow rates of the first RO concentrated water supplied to the first space 11 of the first-stage membrane module unit (in the example of fig. 2, the first-stage membrane module unit 12) and the dilution water supplied to the second space 13 of the last-stage preceding-stage membrane module unit (in the example of fig. 2, the fourth-stage membrane module unit 18) so that the measured values of the first flow rate measuring device 34, the second flow rate measuring device 36, and the third flow rate measuring device 74 become target flow rate values set in advance.
As a result, in the concentration treatment of water using the semipermeable membrane module, even when there is a variation in the quality of the water to be treated (raw water) while the displacement is reduced by the reverse osmosis membrane method, more stable treatment can be performed. By storing the dilution water passing through the second space of the final stage in the second dilution water tank 68, the flow rate can be easily adjusted even when the balance between the first space and the second space is broken due to the water quality fluctuation of the water to be treated. Further, by using the second pressurizing pump 70 as the second pressurizing pump that sucks in the dilution water of the membrane module unit of the final stage and discharges the dilution water to the membrane module unit of the preceding stage, even when the pressure required for water passage is insufficient by increasing the number of stages of the membrane module unit only by the pressurizing pump 26, the load of the pressurizing pump 26 can be reduced, and the pressure required for water passage can be suppressed.
Specifically, for example, the pressurizing pump 26 is started, and the valve 32 is opened fully (opening degree 100%), for example, to gradually increase the output value of the first inverter 30 attached to the pressurizing pump 26. 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, an arbitrary predetermined ratio (for example, the opening degree is set to 10% with respect to the total opening). Since the measured value of the first flow rate measuring device 34 decreases, the output of the first inverter 30 of the pressurizing pump 26 is increased until the measured value of the first flow rate measuring device 34 reaches the target flow rate. When the valve 32 is closed, the measurement value of the third flow measuring device 74 is increased. Thereafter, the operations of increasing the output of the first inverter 30, increasing the measurement value of the first flow rate measuring device 34, closing the valve 32, decreasing the measurement value of the first flow rate measuring device 34, and increasing the measurement value of the third flow rate measuring device 74 are repeated, and the measurement values of the first flow rate measuring device 34 and the third flow rate measuring device 74 may be adjusted to the target flow rate. The output value may be set by the second inverter 72 attached to the second pressurizing pump 70, and the measured value of the second flow rate measuring device 36 may be adjusted to the target flow rate.
When the recovery rate of the water to be treated 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, and the flow rate of the first RO concentrated water and the flow rate of the dilution water are changed so that the recovery rate of the water to be treated based on the measured value of the first flow rate measuring device 34 and the measured value of the second flow rate measuring device 36 becomes as constant as possible. When the flow rate of the first space measured by the first flow rate measuring device 34 is smaller than the set flow rate, the output value of the first inverter 30 may be fixed and the opening degree of the valve 32 may be increased (i.e., the valve may be opened). The opening degree of the valve 32 may be adjusted by repeating the following steps: the flow rate of the first space measured by the first flow rate measuring device 34 is observed within a predetermined time (for example, 1 minute) by closing a predetermined arbitrary ratio (for example, the opening degree is set to 10% with respect to the total opening). Alternatively, the opening degree of the valve 32 may be fixed, and the output value of the first inverter 30 may be increased to increase the flow rate of the first space.
When the flow rate of 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 reduced. However, when the pressure pump 26 reaches the output lower limit value of the guaranteed operation, the opening degree of the valve 32 is reduced (the valve is closed). The adjustment of the opening degree of the valve 32 may be repeated, for example, by: the flow rate of the first space measured by the first flow rate measuring device 34 is observed within a predetermined time (for example, 1 minute) by closing the valve at a predetermined arbitrary ratio (for example, 10% of the opening degree with respect to the total opening). Alternatively, the output value of the first inverter 30 may be fixed, and the opening degree of the valve 32 may be reduced to reduce the flow rate of the first space.
When the flow rate of the second space measured by the second flow rate measuring device 36 is smaller than the set flow rate, the opening degree of the valve 32 may be fixed and the output value of the second inverter 720 may be increased. When the flow rate of 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 may be fixed and the output value of the second inverter 72 may be reduced.
When the flow rate of the second space measured by the third flow rate measuring device 74 is smaller than the set flow rate, the flow rate of the first space is increased, so that the output value of the first inverter 30 may be fixed and the opening degree of the valve 32 may be reduced. Alternatively, the opening degree of the valve 32 may be fixed, and the output value of the first inverter 30 may be increased. When the flow rate of the second space measured by the third flow rate measuring device 74 is larger than the set flow rate, the flow rate of the first space is reduced, and therefore, the output value of the first inverter 30 may be fixed and the opening degree of the valve 32 may be increased. Alternatively, the opening degree of the valve 32 may be fixed, and the output value of the first inverter 30 may be reduced.
The proportional control valve whose opening degree is adjusted based on the measured values of the first flow rate measuring device 34, the second flow rate measuring device 36, and the third flow rate measuring device 74 may be provided in the piping of the first space 11, for example, in one or more of the piping 106, 42, 44, 46, 48, or may be manually adjusted, or may be automatically adjusted by the control device 66.
In addition to the first flow rate measuring device 34 that measures the flow rate of the concentrated water passing through the first space of the membrane module unit of the final stage and the third flow rate measuring device 74 that measures the flow rate of the diluted water passing through the second space of the membrane module unit of the final stage, one or more flow rate measuring devices that measure the flow rate of the first space 11 may be provided in the piping of the first space 11, for example, in the piping 106, 42, 44, 46, 48.
In addition to the second flow rate measuring device 36 for measuring the flow rate of the dilution water passing through the second space of the first-stage membrane module unit, one or more flow rate measuring devices for measuring the flow rate of the second space 13 may be provided in the piping of the second space 13, for example, in the piping 78, 56, 58, 60.
One or more proportional control valves for adjusting the opening degree based on the measured values of the first flow rate measuring device 34, the second flow rate measuring device 36, and the third flow rate measuring device 74 may be provided in the piping of the first space 11, for example, in the piping 106, 42, 44, 46, 48.
The second dilution water tank 68 may not be provided in the water treatment apparatus 2. Fig. 3 shows a water treatment apparatus having such a structure.
In the water treatment apparatus 3 shown in fig. 3, a third flow rate measuring device 84 for measuring the flow rate of the dilution water passing through the second space of the membrane module unit of the final stage (in the example of fig. 3, the fifth-stage membrane module unit 20) is provided as a third flow rate measuring unit in the piping 54. 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 are connected in parallel by piping 54 via a second booster pump 80. The water treatment apparatus 3 may or may not include the concentrate tank 22, the pump 28, and the pipe 52. The water treatment apparatus 3 may or may not include the first dilution water tank 24 and the pipe 64.
The second booster pump 80 is provided with, for example, a second inverter 82 that outputs a driving frequency corresponding to the inputted command signal to the second booster pump 80. The water treatment apparatus 3 includes a control device 66, and the control device 66 is connected to the first inverter 30, the second inverter 82, the first flow rate measuring device 34, the second flow rate measuring device 36, and the third flow rate measuring device 84 by wired or wireless electrical connection or the like. The control device 66 may also be connected to the valve 32 by a wired or wireless electrical connection or the like.
In the water treatment method and the water treatment apparatus 3 according to the present embodiment, the flow rate of the concentrated water passing through the first space of the membrane module unit of the final stage (first flow rate measurement step), the flow rate of the diluted water passing through the second space of the membrane module unit of the first stage (second flow rate measurement step), and the flow rate of the diluted water passing through the second space of the membrane module unit of the final stage (third flow rate measurement step) are measured, and the flow rates of the first RO concentrated water supplied to the first space of the membrane module unit of the first stage and the diluted water supplied to the second space of the membrane module unit of the preceding stage of the final stage are adjusted so that the measured value of the flow rate of the concentrated water of the final stage, the measured value of the flow rate of the diluted water of the first stage, and the measured value of the flow rate of the diluted water of the final stage become target flow rate values set in advance (flow rate adjustment step).
For example, the control device 66 functions as a flow rate adjustment means for adjusting 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 the dilution water supplied to the second space of the final-stage membrane module unit such that the measurement value of the flow rate of the concentrated water in the final-stage membrane module unit (in the example of fig. 2, the fifth-stage membrane module unit 20) measured by the first flow rate measurement means 34, the measurement value of the flow rate of the dilution water in the first-stage membrane module unit (in the example of fig. 2, the first-stage membrane module unit 12) measured by the second flow rate measurement means 36, and the measurement value of the flow rate of the dilution water in the final-stage membrane module unit measured by the third flow rate measurement means 84 are set to target flow rate values set in advance. The control device 66 calculates the driving frequency by using an arbitrary operation formula, outputs a command signal corresponding to the calculated value to the first inverter 30 to control the booster pump 26, and outputs the command signal to the second inverter 82 to control the second booster pump 80, and adjusts the flow rates of the first RO concentrated water supplied to the first space 11 of the first-stage membrane module unit (in the example of fig. 2, the first-stage membrane module unit 12) and the dilution water supplied to the second space 13 of the last-stage preceding-stage membrane module unit (in the example of fig. 2, the fourth-stage membrane module unit 18) so that the measured values of the first flow rate measuring device 34, the second flow rate measuring device 36, and the third flow rate measuring device 84 become target flow rate values set in advance.
As a result, in the concentration treatment of water using the multi-stage semipermeable membrane module, even when there is a fluctuation in the quality of the water to be treated (raw water) while the displacement is reduced by the reverse osmosis membrane method, more stable treatment can be performed. Further, by using the second pressurizing pump 80 as the second pressurizing pump that sucks in the dilution water of the membrane module unit of the final stage and discharges the dilution water to the membrane module unit of the preceding stage, even when the pressure required for water passage is insufficient by increasing the number of stages of the membrane module unit only by the pressurizing pump 26, the load of the pressurizing pump 26 can be reduced, and the pressure required for water passage can be suppressed.
Fig. 4 schematically shows another example of the water treatment apparatus according to the embodiment of the present invention.
The water treatment apparatus 4 shown in fig. 4 is different from the water treatment apparatus 1 shown in fig. 1 in that: the first space outlet of each membrane module of the fourth-stage membrane module unit 18 and the first space inlet of each membrane module of the fifth-stage membrane module unit 20 are connected in parallel by a pipe 88, and the downstream side of the pump 28 in the pipe 52 and the second space inlet of each membrane module of the fifth-stage membrane module unit 20 are connected in parallel by a pipe 90 via a valve 86.
The water treatment device 4 is as follows: using a multistage membrane module having a first space 11 and a second space 13 separated by a semipermeable membrane 15, the first RO concentrate is introduced into the first space 11 of the multistage membrane module in series, the concentrate of the final stage membrane module is distributed to the second space 13 of the final stage membrane module unit (in the example of fig. 4, the fifth stage membrane module unit 20), the dilution water of the final stage membrane module is returned into the second space 13 of the preceding stage membrane module in series, and the first space 11 is pressurized to allow the water contained in the first space 11 to permeate into the second space 13, thereby concentrating the water. That is, in the water treatment apparatus 4, the first RO concentrated water is concentrated using the semipermeable membrane 15, and the concentrated water is further concentrated using the semipermeable membrane 15 of the next stage. The first RO concentrate is supplied to the first space 11 of the first-stage membrane module unit (first-stage membrane module unit 12 in the example of fig. 4), and after the concentrate passes through the first space 11 of the final-stage membrane module unit (fifth-stage membrane module unit 20 in the example of fig. 1), at least a part of the final-stage concentrate is supplied to the second space 13 of the final-stage membrane module. Then, the dilution water having passed through the second space 13 of the membrane module of the final stage is supplied to the second space 13 of the membrane module upstream thereof, and the first space 11 of the membrane module of each stage is pressurized to allow water contained in the first space 11 to permeate into the second space 13.
Specifically, in the water treatment apparatus 4, the water to be treated containing the total dissolved solid content is stored in the water tank 10 to be treated through the pipe 38 as needed, pressurized to 0.1MPa or more by the pressurizing pump 26 from the water tank 10 to be treated (pressurizing step), and the liquid is sent to the first reverse osmosis membrane treatment apparatus 100 through the pipe 40. In the first reverse osmosis membrane treatment apparatus 100, pressurized water to be treated is passed through a first reverse osmosis membrane to obtain first RO permeate and first RO concentrate (first reverse osmosis membrane treatment step). The first RO permeate is discharged through the first RO permeate pipe 108. At least a part of the first RO permeate may be further sent to the third reverse osmosis membrane treatment apparatus 104 as described later, and reverse osmosis membrane treatment may be performed in the third reverse osmosis membrane treatment apparatus 104 (third reverse osmosis membrane treatment step).
The first RO concentrate is fed to the first space 11 of each membrane module of the first stage membrane module unit 12 through the first RO concentrate pipe 106. 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, the second space 13 of the third-stage membrane module unit 16, and the second space 13 of the second-stage membrane module unit 14 is fed to the second spaces 13 of the respective membrane modules of the first-stage membrane module unit 12 through the piping 60. In each membrane module of the first-stage membrane module unit 12, the first space 11 is pressurized, and water contained in the first space 11 is permeated into the second space 13 (concentration step (first stage)).
The concentrated water of the first-stage membrane module unit 12 is fed to the first space 11 of each membrane module of the second-stage membrane module unit 14 through the piping 42. On the other hand, the dilution water returned from the fifth-stage membrane module unit 20 of the final stage, which will be described later, through the second space 13 of the fourth-stage membrane module unit 18 and the second space 13 of the third-stage membrane module unit 16 is sent to the second spaces 13 of the respective membrane modules of the second-stage membrane module unit 14 through the piping 58. In each membrane module of the second-stage membrane module unit 14, the first space 11 is pressurized, and water contained in the first space 11 is permeated into the second space 13 (concentration step (second stage)) as in the first stage.
The concentrated water of the second-stage membrane module unit 14 is fed to the first space 11 of each membrane module of the third-stage membrane module unit 16 through the piping 44. On the other hand, the dilution water returned from the fifth-stage membrane module unit 20 of the final stage, which will be described later, through the second space 13 of the fourth-stage membrane module unit 18 is sent to the second space 13 of each membrane module of the third-stage membrane module unit 16 through the pipe 56. In the respective membrane modules of the third-stage membrane module unit 16, the first space 11 is pressurized and water contained in the first space 11 is permeated into the second space 13 (concentration step (third stage)) in the same manner as in the first and second stages.
The concentrated water of the third-stage membrane module unit 16 is fed to the first space 11 of each membrane module of the fourth-stage membrane module unit 18 through the piping 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 piping 92. In the respective membrane modules of the fourth-stage membrane module unit 18, the first space 11 is pressurized and water contained in the first space 11 is permeated into the second space 13 (concentration step (fourth stage)) in the same manner as the first, second and third stages.
The concentrated water of the fourth-stage membrane module unit 18 is fed to the first space 11 of each membrane module of the fifth-stage membrane module unit 20 of the final stage through the piping 88. On the other hand, the 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 piping 90. In the fifth-stage membrane module unit 20, the first space 11 is pressurized and water contained in the first space 11 is permeated into the second space 13 (concentration step (fifth stage)) in the same manner as in the first to fourth stages.
The concentrate of the fifth-stage membrane module unit 20 is fed to the concentrate tank 22 and stored as needed through the pipe 50 with the valve 32 opened. When the valve 86 is closed, at least a part of the concentrated water is discharged as treated water from the concentrated water tank 22 to the outside of the system through the pipe 52 by the pump 28. At least a part of the concentrated water may be fed to the water tank 10 to be treated, and mixed with the water to be treated in the water tank 10 to be treated.
At least a part of the concentrate of the fifth-stage membrane module unit 20 is fed from the concentrate tank 22 to the second space 13 of each membrane module of the fifth-stage membrane module unit 20 by the pump 28 through the pipe 52 and the pipe 90 with the valve 86 opened. As described above, in each membrane module of the fifth-stage membrane module unit 20, the first space 11 is pressurized, and water contained in the first space 11 is permeated into the second space 13 (concentration step (fifth stage)). Here, the pump 28, the pipes 52, 90, and the like function as a 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. As shown in the water treatment apparatus 17 of fig. 10, the concentrated water in the fifth-stage membrane module unit 20 may be fed to the second space 13 of each membrane module in the fifth-stage membrane module unit 20 through the pipe 50 and the pipe 91 when the valve 87 is opened, by branching from the pipe 50 from the first space outlet of each membrane module in the fifth-stage membrane module unit 20 to the second space inlet of each membrane module in the fifth-stage membrane module unit 20 via the pipe 91 of the valve 87, without providing the concentrated water tank 22 and the pump 28. The water treatment apparatus 4 may or may not include the first dilution water tank 24 and the pipe 64.
The dilution water of the fifth-stage membrane module unit 20 is sent to the second space 13 of each membrane module of the fourth-stage membrane module unit 18 through the piping 92. As described above, in each membrane module of the fourth-stage membrane module unit 18, the first space 11 is pressurized, and water contained in the first space 11 is permeated into the second space 13 (concentration step (fourth stage)).
The dilution water of the fourth-stage membrane module unit 18 is fed to the second space 13 of each membrane module of the third-stage membrane module unit 16 through the piping 56. As described above, in each membrane module of the third-stage membrane module unit 16, the first space 11 is pressurized, and water contained in the first space 11 is permeated into the second space 13 (concentration step (third stage)).
The dilution water of the third-stage membrane module unit 16 is supplied to the second space 13 of each membrane module of the second-stage membrane module unit 14 through the piping 58. As described above, in each membrane module of the second-stage membrane module unit 14, the first space 11 is pressurized, and water contained in the first space 11 is permeated into the second space 13 (concentration step (second stage)).
The dilution water of the second-stage membrane module unit 14 is fed to the second space 13 of each membrane module of the first-stage membrane module unit 12 through the piping 60. As described above, in each membrane module of the first-stage membrane module unit 12, the first space 11 is pressurized, and water contained in the first space 11 is permeated into the second space 13 (concentration step (first stage)).
The dilution water of the first-stage membrane module unit 12 is fed to the first dilution water tank 24 through a pipe 62 as needed, stored, and then discharged to the outside of the system through a pipe 64. At least a part of the dilution water may be fed to the water tank 10 to be treated, and mixed with the water to be treated in the water tank 10 to be treated. At least a part of the dilution water may be further fed to the second reverse osmosis membrane treatment apparatus 102 as described later, and the second reverse osmosis membrane treatment apparatus 102 may perform reverse osmosis membrane treatment (second reverse osmosis membrane treatment step).
The treatment is performed as described above, and the treated water (final-stage concentrated water) in which the substances such as the total dissolved solids and the like are concentrated and the dilution water are obtained from the treated water containing the total dissolved solids and the like as the treatment target, thereby reducing the volume of the treated water.
For example, the control device 66 functions as a flow rate adjustment means for adjusting the flow rate of the first RO concentrated water supplied to the first space of the first-stage membrane module unit so that the measured value of the flow rate of the concentrated water of the final-stage membrane module unit (the fifth-stage membrane module unit 20 in the example of fig. 1) measured by the first flow rate measurement means 34 and the measured value of the flow rate of the dilution water of the first-stage membrane module unit (the first-stage membrane module unit 12 in the example of fig. 1) measured by the second flow rate measurement means 36 become target flow rate values set in advance. The control device 66 calculates the driving frequency using an arbitrary operation formula, outputs a command signal corresponding to the calculated value to the first inverter 30 to control the booster pump 26, and adjusts the flow rate of the first RO concentrated water supplied to the first space 11 of the first-stage membrane module unit (in the example of fig. 1, the first-stage membrane module unit 12) so that the measured values of the first flow rate measuring device 34 and the second flow rate measuring device 36 become target flow rate values set in advance.
As a result, in the concentration treatment of water using the semipermeable membrane module, even when there is a variation in the quality of the water to be treated (raw water) while the displacement is reduced by the reverse osmosis membrane method, stable treatment can be performed.
In the water treatment apparatus 4, similarly to the water treatment apparatus 2 shown in fig. 2, the flow rate of the dilution water passing through the second space of the membrane module unit of the final stage may be further measured, and the flow rate of the first RO concentrate supplied to the first space of the membrane module unit of the first stage and the flow rate of the dilution water supplied to the second space of the preceding stage of the final stage may be adjusted so that the measured value of the flow rate of the concentrate of the final stage, the measured value of the flow rate of the dilution water of the first stage, and the measured value of the flow rate of the dilution water of the final stage become target flow rate values set in advance. Fig. 5 shows a water treatment apparatus having such a structure.
The water treatment apparatus 5 shown in fig. 5 further includes a second dilution water tank 68 for storing dilution water from the membrane module unit of the final stage (in the example of fig. 5, dilution water from the membrane module unit 20 of the fifth stage). In the water treatment apparatus 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 and the second space inlet of each membrane module of the fourth-stage membrane module unit 18 are connected in parallel by a piping 78 via the second booster pump 70. In addition, as in the water treatment apparatus 17 of fig. 10, the condensed water in the fifth-stage membrane module unit 20 may be fed to the second space 13 of each membrane module in the fifth-stage membrane module unit 20 through the pipe 50 and the pipe 91 in the open state of the valve 87 by branching from the pipe 50 from the first space outlet of each membrane module in the fifth-stage membrane module unit 20 to the second space inlet of each membrane module in the fifth-stage membrane module unit 20 on the front side of the valve 32 and connecting the pipe 91 to the second space inlet of each membrane module in the fifth-stage membrane module unit 20 through the pipe 91 via the pipe 87 without providing the condensed water tank 22 and the pump 28. The water treatment apparatus 5 may or may not include the first dilution water tank 24 and the pipe 64.
The dilution water in the fifth-stage membrane module unit 20 is supplied to the second dilution water tank 68 through the pipe 94, stored, and then supplied from the second dilution water tank 68 to the second space 13 of each membrane module in the fourth-stage membrane module unit 18 through the pipe 78 by the second pressurizing pump 70. As described above, in each membrane module of the fourth-stage membrane module unit 18, the first space 11 is pressurized, and water contained in the first space 11 is permeated into the second space 13 (concentration step (fourth stage)).
The piping 94 is provided with a third flow rate measuring device 74 as a third flow rate measuring means for measuring the flow rate of the dilution water passing through the second space of the final-stage membrane module unit (in the example of fig. 5, the fifth-stage membrane module unit 20). The second pressurizing pump 70 is provided at the subsequent stage of the final-stage membrane module unit (fifth-stage membrane module unit 20 in the example of fig. 2), and is, for example, a second pressurizing pump that is driven at a rotational speed corresponding to the inputted driving frequency, sucks in the dilution water of the final-stage membrane module unit (dilution water of the fifth-stage membrane module unit 20 in the example of fig. 2), and ejects the dilution water toward the front-stage membrane module unit (fourth-stage membrane module unit 18 in the example of fig. 2). The second booster pump 70 is provided with, for example, a second inverter 72 that outputs a driving frequency corresponding to the inputted command signal to the second booster pump 70. The installation locations of the second dilution water tank 68, the second pressurizing pump 70, and the flow rate measuring device 74 are not limited to the positions shown in fig. 5, and may be any of the pipes for the dilution water in the middle, for example, any of the pipes 56, 58, and 60. The water treatment apparatus 5 includes a control device 66, and the control device 66 is connected to the first inverter 30, the second inverter 72, the first flow rate measuring device 34, the second flow rate measuring device 36, and the third flow rate measuring device 74 by wired or wireless electrical connection or the like. The control device 66 may also be connected to the valve 32 by a wired or wireless electrical connection or the like.
In the water treatment method and the water treatment apparatus 5 according to the present embodiment, the flow rate of the concentrated water passing through the first space of the membrane module unit of the final stage (first flow rate measurement step), the flow rate of the diluted water passing through the second space of the membrane module unit of the first stage (second flow rate measurement step), and the flow rate of the diluted water passing through the second space of the membrane module unit of the final stage (third flow rate measurement step) are measured, and the flow rates of the first RO concentrated water supplied to the first space of the membrane module unit of the first stage and the diluted water supplied to the second space of the membrane module unit of the preceding stage of the final stage are adjusted so that the measured value of the flow rate of the concentrated water of the final stage, the measured value of the flow rate of the diluted water of the first stage, and the measured value of the flow rate of the diluted water of the final stage become target flow rate values set in advance (flow rate adjustment step).
For example, the control device 66 functions as a flow rate adjustment means for adjusting 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 the dilution water supplied to the second space of the final-stage membrane module unit so that the measured value of the flow rate of the concentrated water of the final-stage membrane module unit (in the example of fig. 5, the fifth-stage membrane module unit 20) measured by the first flow rate measurement means 34, the measured value of the flow rate of the dilution water of the first-stage membrane module unit (in the example of fig. 5, the first-stage membrane module unit 12) measured by the second flow rate measurement means 36, and the measured value of the flow rate of the dilution water of the final-stage membrane module unit measured by the third flow rate measurement means 74 become target flow rate values set in advance. The control device 66 calculates the driving frequency by using an arbitrary operation formula, outputs a command signal corresponding to the calculated value to the first inverter 30 to control the booster pump 26, outputs the command signal to the second inverter 72 to control the second booster pump 70, and adjusts the flow rates of the first RO concentrated water supplied to the first space 11 of the first-stage membrane module unit (in the example of fig. 5, the first-stage membrane module unit 12) and the dilution water supplied to the second space 13 of the last-stage preceding-stage membrane module unit (in the example of fig. 5, the fourth-stage membrane module unit 18) so that the measured values of the first flow rate measuring device 34, the second flow rate measuring device 36, and the third flow rate measuring device 74 become target flow rate values set in advance.
As a result, in the concentration treatment of water using the semipermeable membrane module, even when there is a variation in the quality of the water to be treated (raw water) while the displacement is reduced by the reverse osmosis membrane method, more stable treatment can be performed. By storing the dilution water passing through the second space of the final stage in the second dilution water tank 68, the flow rate can be easily adjusted even when the balance between the first space and the second space is broken due to the water quality fluctuation of the water to be treated. Further, by using the second pressurizing pump 70 as the second pressurizing pump that sucks in the dilution water of the membrane module unit of the final stage and discharges the dilution water to the membrane module unit of the preceding stage, even when the pressure required for water passage is insufficient due to an increase in the number of stages of the membrane module unit only by the pressurizing pump 26, the load of the pressurizing pump 26 can be reduced, and the pressure required for water passage can be suppressed.
In the water treatment apparatus 5, the second dilution water tank 68 may not be provided in the same manner as the water treatment apparatus 3 shown in fig. 3. Fig. 6 shows a water treatment apparatus having such a structure.
In the water treatment apparatus 6 shown in fig. 6, a third flow rate measuring device 84 for measuring the flow rate of the dilution water passing through the second space of the membrane module unit of the final stage (in the example of fig. 6, the fifth-stage membrane module unit 20) is provided as a third flow rate measuring unit in the piping 92. 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 are connected in parallel by piping 92 via a second booster pump 80. In addition, as in the water treatment apparatus 17 of fig. 10, the condensed water in the fifth-stage membrane module unit 20 may be fed to the second space 13 of each membrane module in the fifth-stage membrane module unit 20 through the pipe 50 and the pipe 91 in the open state of the valve 32 by branching from the pipe 50 from the first space outlet of each membrane module in the fifth-stage membrane module unit 20 to the second space inlet of each membrane module in the fifth-stage membrane module unit 20 through the pipe 91 of the valve 87, without providing the condensed water tank 22 and the pump 28. The water treatment apparatus 6 may or may not include the first dilution water tank 24 and the pipe 64.
The second booster pump 80 is provided with, for example, a second inverter 82 that outputs a driving frequency corresponding to the inputted command signal to the second booster pump 80. The water treatment apparatus 6 includes a control device 66, and the control device 66 is connected to the first inverter 30, the second inverter 82, the first flow rate measuring device 34, the second flow rate measuring device 36, and the third flow rate measuring device 84 by wired or wireless electrical connection or the like. The control device 66 may also be connected to the valve 32 by a wired or wireless electrical connection or the like.
In the water treatment method and the water treatment apparatus 6 according to the present embodiment, the flow rate of the concentrated water passing through the first space of the membrane module unit of the final stage (first flow rate measurement step), the flow rate of the diluted water passing through the second space of the membrane module unit of the first stage (second flow rate measurement step), and the flow rate of the diluted water passing through the second space of the membrane module unit of the final stage (third flow rate measurement step) are measured, and the flow rates of the first RO concentrated water supplied to the first space of the membrane module unit of the first stage and the diluted water supplied to the second space of the membrane module unit of the preceding stage of the final stage are adjusted so that the measured value of the flow rate of the concentrated water of the final stage, the measured value of the flow rate of the diluted water of the first stage, and the measured value of the flow rate of the diluted water of the final stage become target flow rate values set in advance (flow rate adjustment step).
For example, the control device 66 functions as a flow rate adjustment means for adjusting 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 the dilution water supplied to the second space of the preceding-stage membrane module unit in the final stage so that the measurement value of the flow rate of the concentrated water in the final-stage membrane module unit (in the example of fig. 6, the fifth-stage membrane module unit 20) measured by the first flow rate measurement means 34, the measurement value of the flow rate of the dilution water in the first-stage membrane module unit (in the example of fig. 6, the first-stage membrane module unit 12) measured by the second flow rate measurement means 36, and the measurement value of the flow rate of the dilution water in the final-stage membrane module unit measured by the third flow rate measurement means 84 become target flow rate values set in advance. The control device 66 calculates the driving frequency by using an arbitrary operation formula, outputs a command signal corresponding to the calculated value to the first inverter 30 to control the booster pump 26, outputs the command signal to the second inverter 82 to control the second booster pump 80, and adjusts the flow rates of the first RO concentrate supplied to the first space 11 of the first-stage membrane module unit (in the example of fig. 6, the first-stage membrane module unit 12) and the diluent supplied to the second space 13 of the last-stage preceding-stage membrane module unit (in the example of fig. 6, the fourth-stage membrane module unit 18) so that the measured values of the first flow rate measuring device 34, the second flow rate measuring device 36, and the third flow rate measuring device 84 become target flow rate values set in advance.
As a result, in the concentration treatment of water using the semipermeable membrane module, even when there is a variation in the quality of the water to be treated (raw water) while the displacement is reduced by the reverse osmosis membrane method, more stable treatment can be performed. Further, by using the second pressurizing pump 80 as the second pressurizing pump that sucks in the dilution water of the membrane module unit of the final stage and discharges the dilution water to the membrane module unit of the preceding stage, even when the pressure required for water passage is insufficient by increasing the number of stages of the membrane module unit only by the pressurizing pump 26, the load of the pressurizing pump 26 can be reduced, and the pressure required for water passage can be suppressed.
In the water treatment method and the water treatment apparatus according to the present embodiment, the number of stages of the membrane module unit may be determined according to the concentration of the target treated water or the like. For example, when it is desired to obtain more concentrated treated water from less concentrated treated water, the number of stages of the membrane module unit may be increased.
The number of membrane modules in each membrane module unit may be determined based on the flow rate of the first RO permeate water or the like.
In the water treatment method and the water treatment apparatus according to the present embodiment, it is preferable that only the front stage of the first reverse osmosis membrane treatment apparatus 100 is provided with a pressurizing pump as pressurizing means for pressurizing the water to be treated containing the total dissolved solid content to 0.1MPa or more. That is, it is preferable that no pressurizing means (pump or the like) be provided between the first reverse osmosis membrane treatment apparatus 100 and the first-stage membrane module unit 12, and the first RO concentrate of the first reverse osmosis membrane treatment apparatus 100 be directly introduced into the first-stage membrane module unit 12 by pressurization by the pressurizing pump 26. By operating the reverse osmosis membrane device and the semipermeable membrane module with 1 booster pump, equipment cost, power cost, equipment space, and the like can be reduced.
The first reverse osmosis membrane used in the first reverse osmosis membrane treatment apparatus 100 preferably has a membrane surface effective pressure of 0.2 to 0.7m at 25 ℃ and 1MPa 3 /m 2 Pure water permeation flux in the range of/day, and has a characteristic of 99.5% or more of NaCl removal rate at standard operating pressure (NaCl at 32,000 mg/L). The first reverse osmosis membrane preferably has a membrane surface effective pressure of 1MPa and a membrane surface effective pressure of 0.3 to 0.6m at 25 DEG C 3 /m 2 Pure water permeation flux in the range of/day, and has a characteristic of a NaCl removal of 97% or more at a standard operating pressure. Under the condition that the effective pressure of the membrane surface is 1MPa and the temperature is 25 ℃, the permeation flux of pure water is less than 0.2m 3 /m 2 At day/time, there is a possibility that a sufficient RO permeate amount exceeding 0.7m may not be obtained 3 /m 2 On day/time, the RO permeate amount becomes excessive, and clogging of the membrane may occur.
The first reverse osmosis membrane treatment apparatus 100 may be a multistage reverse osmosis membrane treatment apparatus. In this case, the RO concentrate of each stage is passed to a reverse osmosis membrane treatment device of the next stage to perform reverse osmosis membrane treatment, and the RO concentrate of the final stage is used as the first RO concentrate and fed to the first space 11 of each membrane module of the first-stage membrane module unit 12. The RO permeate water in each stage may be discharged, or at least a part of the RO permeate water may be further sent to the third reverse osmosis membrane treatment apparatus 104 as described later, and reverse osmosis membrane treatment may be performed in the third reverse osmosis membrane treatment apparatus 104 (third reverse osmosis membrane treatment step).
The permeation flux of the semipermeable membrane module in the semipermeable membrane treatment step is preferably in the range of 0.005m/d to 0.05m/d, more preferably in the range of 0.015m/d to 0.04m/d, under conditions of an effective membrane surface pressure of 1MPa and 25 ℃. If the permeation flux of the semipermeable membrane modules is less than 0.005m/d at a membrane surface effective pressure of 1MPa and 25 ℃, the number of semipermeable membrane modules required may be increased, and if the permeation flux exceeds 0.05m/d, clogging of the membrane may occur.
In the water treatment method and the water treatment apparatus according to the present embodiment, the pressure of the first RO concentrated water immediately after the first reverse osmosis membrane step is preferably 7MPa or more, and the apparatus further includes a depressurizing step of depressurizing the first RO concentrated water to less than 7MPa in a stage preceding the semipermeable membrane treatment step (first-stage membrane module unit 12). An example of such a structure is shown in fig. 7.
In the water treatment apparatus 7 of fig. 7, the concentrate water outlet of the first reverse osmosis membrane treatment apparatus 100 and the first space inlet of each membrane module of the first-stage membrane module unit 12 are connected in parallel through the first RO concentrate water pipe 106 via the pressure reducing valve 118 as a pressure reducing means. The other structures are the same as those of the water treatment apparatus 1 of fig. 1. In the water treatment apparatuses 2 to 6 and 17 of fig. 2 to 6 and 10, the first RO concentrate water piping 106 may be provided with a pressure reducing valve 118. According to this configuration, the first RO concentrate can be depressurized to a pressure smaller than 7MPa, which is the upper pressure limit of the semipermeable membrane module, at the stage preceding the semipermeable membrane treatment step. In the water treatment apparatus 7, it is preferable that a pressurizing means (a pump or the like) is not provided between the first reverse osmosis membrane treatment apparatus 100 and the first-stage membrane module unit 12, and the first RO concentrate of the first reverse osmosis membrane treatment apparatus 100 is depressurized by the pressure pump 26 through the pressure reducing valve 118 and then directly introduced into the first-stage membrane module unit 12. The water treatment apparatus 7 may or may not include the concentrate tank 22, the pump 28, and the pipe 52. The water treatment apparatus 7 may or may not include the first dilution water tank 24 and the pipe 64.
The pressure of the first RO concentrated water immediately after the first reverse osmosis membrane step is preferably 7MPa or more, more preferably in the range of 7 to 12MPa, and still more preferably in the range of 7 to 10 MPa. When the pressure of the first RO concentrated water immediately after the first reverse osmosis membrane step is 7MPa, the concentrated water may not be efficiently concentrated to a high concentration, and the upper limit is preferably 12MPa from the viewpoint of the pressure resistance of the reverse osmosis membrane.
From the viewpoint of pressure resistance of the semipermeable membrane module, the first RO concentrate is preferably depressurized to less than 7MPa, more preferably to a pressure in the range of 3.0MPa to 6.9MPa, in the preceding stage of the semipermeable membrane treatment process (first stage membrane module unit 12).
The pressure reducing means is not particularly limited as long as it can reduce the pressure of the first RO concentrated water, and includes a pressure reducing valve, an orifice, and the like.
The water treatment method and the water treatment apparatus according to the present embodiment may further include a second reverse osmosis membrane treatment step of passing the dilution water to a second reverse osmosis membrane to obtain second RO permeate and second RO concentrate. An example of such a structure is shown in fig. 8.
In the water treatment apparatus 8 of fig. 8, the outlet of the first dilution water tank 24 and the inlet of the second reverse osmosis membrane treatment apparatus 102 are connected via a pump 120 through a pipe 64. A second RO concentrate piping 110 is connected to the concentrate outlet of the second reverse osmosis membrane treatment device 102, and a second RO permeate piping 112 is connected to the permeate outlet. The other structures are the same as those of the water treatment apparatus 1 of fig. 1. The water treatment apparatuses 2 to 7 and 17 shown in fig. 2 to 7 and 10 may be provided with a second reverse osmosis membrane treatment apparatus 102. The water treatment apparatus 8 may or may not include the concentrate tank 22, the pump 28, and the pipe 52. The water treatment apparatus 8 may or may not include the first dilution water tank 24. In this case, the pipe 62 and the pipe 64 may be connected, and the pump 120 may be provided in the pipe 62 or the pipe 64, or may not be provided.
At least a part of the dilution water is sent to the second reverse osmosis membrane treatment apparatus 102 through the piping 64 by the pump 120, and the second reverse osmosis membrane treatment apparatus 102 performs reverse osmosis membrane treatment to obtain second RO concentrated water and second RO permeate water (second reverse osmosis membrane treatment step). The second RO permeate obtained by the second reverse osmosis membrane treatment apparatus 102 is discharged to the outside of the system through a second RO permeate pipe 112. The third RO concentrated water obtained by reverse osmosis membrane treatment may be discharged to the outside of the system through the second RO concentrated water pipe 110, or may be sent to the water tank 10 to be treated, and mixed with the water to be treated in the water tank 10 to be treated. According to this configuration, the dilution water can be reused as the second RO permeate water.
The water treatment method and the water treatment apparatus according to the present embodiment may further include a third reverse osmosis membrane treatment step of passing at least one of the first RO permeate and the second RO permeate through the third reverse osmosis membrane to obtain third RO permeate and third RO concentrate. An example of such a structure is shown in fig. 9.
In the water treatment apparatus 9 of fig. 9, the permeate outlet of the first reverse osmosis membrane treatment apparatus 100 and the inlet of the third reverse osmosis membrane treatment apparatus 104 are connected by a first RO permeate pipe 108. A third RO concentrate piping 114 is connected to the concentrate outlet of the third reverse osmosis membrane treatment device 104, and a third RO permeate piping 116 is connected to the permeate outlet. The other structures are the same as those of the water treatment apparatus 1 of fig. 1. The water treatment apparatuses 2 to 8 and 17 shown in fig. 2 to 8 and 10 may be provided with a third reverse osmosis membrane treatment apparatus 104. The water treatment apparatus 9 may or may not include the concentrate tank 22, the pump 28, and the pipe 52. The water treatment apparatus 9 may or may not include the first dilution water tank 24 and the pipe 64.
At least a part of the first RO permeate is sent to the third reverse osmosis membrane treatment apparatus 104 through the first RO permeate pipe 108, and the third RO concentrate and the third RO permeate are obtained by performing reverse osmosis membrane treatment in the third reverse osmosis membrane treatment apparatus 104 (third reverse osmosis membrane treatment step). The third RO permeate obtained by the third reverse osmosis membrane treatment device 104 is discharged to the outside of the system through a third RO permeate pipe 116. The third RO concentrated water obtained by the reverse osmosis membrane treatment may be discharged to the outside of the system through the third RO concentrated water pipe 114, or may be sent to the water tank 10 to be treated, and mixed with the water to be treated in the water tank 10 to be treated. According to this configuration, the third RO permeate can be reused.
The water treatment apparatus 8 of fig. 8 may further include a reverse osmosis membrane treatment step of passing the second RO permeate water through a reverse osmosis membrane to obtain RO permeate water and RO concentrate water.
Examples of the semipermeable membrane 15 included in the membrane module include semipermeable membranes such as a reverse osmosis membrane (RO membrane), a forward osmosis membrane (FO membrane), and a nanofiltration membrane (NF membrane). The semipermeable membrane is preferably a reverse osmosis membrane, a forward osmosis membrane or a nanofiltration membrane. In the case of using a reverse osmosis membrane, a forward osmosis membrane, or a nanofiltration membrane as the semipermeable membrane, the pressure of the target solution in the first space 11 is preferably 0.5 to 10.0MPa.
The material constituting the semipermeable membrane 15 is not particularly limited, and examples thereof include cellulose resins such as cellulose acetate resins, polysulfone resins such as polyether sulfone resins, polyamide resins, and the like. The material constituting the semipermeable membrane 15 is preferably a cellulose acetate resin.
Examples of the shape of the semipermeable membrane 15 include a flat membrane, a hollow fiber membrane, and a spiral membrane.
The water to be treated is not particularly limited as long as it contains a substance such as Total Dissolved Solids (TDS), and examples thereof include factory drainage, brine, seawater, chemical waste liquid, and concentrated drainage after reverse osmosis membrane treatment. The water treatment method and the water treatment apparatus according to the present embodiment can be suitably applied to a case where the TDS (total dissolved solid content) concentration of the water to be treated is, for example, 50000mg/L or more, preferably 60000mg/L or more, and more preferably 100000mg/L or more. TDS (total dissolved solid content) is composed of, for example, a chloride such as sodium chloride, a carbonate such as calcium carbonate or magnesium carbonate, a sulfate such as calcium sulfate or magnesium sulfate.
The water treatment method and the water treatment apparatus according to the present embodiment can be suitably applied when the concentration of sulfuric acid ions in the first RO concentrated water is 20000mg/L or more and the concentration of at least one of sodium ions and ammonium ions is 10000mg/L or more. The concentration of the sulfuric acid ion in the first RO concentrated water is preferably 40000mg/L or more, more preferably 40000 to 250000 mg/L. The concentration of at least one of sodium ions and ammonium ions in the first RO concentrated water is preferably 20000mg/L or more, more preferably in the range of 20000 to 100000 mg/L.
(description of the reference numerals)
1. 2, 3, 4, 5, 6, 7, 8, 9, 17 water treatment apparatus, 10 treated water tank, 11 first space, 12 first stage membrane module unit, 13 second space, 14 second stage membrane module unit, 15 semipermeable membrane, 16 third stage membrane module unit, 18 fourth stage membrane module unit, 20 fifth stage membrane module unit, 22 concentrate tank, 24 first dilution water tank, 26 pressurization pump, 28, 120 pump, 30 first inverter, 32, 86, 87 valve, 34 first flow measuring apparatus, 36 second flow measuring apparatus, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 76, 78, 88, 90, 91, 92, 94 piping, 66 control apparatus, 68 second dilution water tank, 70, 80 second pressurization pump, 72, 82 second inverter, 74, 84 third flow measuring apparatus, 100 first reverse osmosis membrane apparatus, 102 second reverse osmosis membrane apparatus, 104 third reverse osmosis membrane apparatus, 106 first concentrate water, 108, second permeate RO, 110, third permeate water, and 112, third permeate water, and 116, and 118 permeate water third permeate water.
Claims (8)
1. A method of treating water, comprising:
a pressurizing step of pressurizing the water to be treated containing the total dissolved solid components to 0.1MPa or more;
A first reverse osmosis membrane treatment step of introducing the pressurized water to be treated into a first reverse osmosis membrane to obtain first RO permeate water and first RO concentrate water;
a semipermeable membrane treatment step of introducing the first RO concentrate into a first space of a first-stage semipermeable membrane module using a semipermeable membrane module having a first space and a second space separated by a semipermeable membrane, pressurizing the first space by pressurizing the first space to permeate the semipermeable membrane to obtain concentrate, further using a semipermeable membrane module of a subsequent stage to the concentrate to obtain concentrate, and introducing a part of the first RO permeate or at least a part of the concentrate or at least a part of the diluent obtained from another semipermeable membrane module into a second space of a semipermeable membrane module of each stage to obtain diluent; and
and a flow rate adjustment step of measuring the flow rate of the concentrated water and the flow rate of the diluted water, and adjusting the flow rate of the first RO concentrated water supplied to the first space of the semipermeable membrane module of the first stage and the flow rate of the diluted water supplied to the second space of the semipermeable membrane module of the preceding stage of the final stage so that the measured value of the flow rate of the concentrated water of the final stage, the measured value of the flow rate of the diluted water of the first stage, and the measured value of the flow rate of the diluted water of the final stage become target flow rate values set in advance.
2. A water treatment method according to claim 1, wherein,
the first reverse osmosis membrane has 0.2-0.7 m under the conditions that the effective pressure of the membrane surface is 1MPa and the temperature is 25 DEG C 3 /m 2 Pure water permeation flux in the range of/day, and has a characteristic that the NaCl removal rate at standard operating pressure is 99.5% or more, which is the NaCl removal rate at 32,000 mg/L.
3. A water treatment method according to claim 1 or 2, wherein,
the first RO concentrated water immediately after the first reverse osmosis membrane treatment step has a pressure of 7MPa or more, and the water treatment method further includes a depressurizing step of depressurizing the first RO concentrated water to less than 7MPa at a stage preceding the semipermeable membrane treatment step.
4. A water treatment method according to claim 1 or 2, wherein,
the water treatment method further comprises the following steps: and a second reverse osmosis membrane treatment step in which the diluted water is passed to a second reverse osmosis membrane to obtain second RO permeate and second RO concentrate.
5. A water treatment device is characterized by comprising:
a pressurizing unit for pressurizing the water to be treated containing the total dissolved solid components to 0.1MPa or more;
A first reverse osmosis membrane treatment unit that introduces the pressurized water to be treated into a first reverse osmosis membrane to obtain first RO permeate water and first RO concentrate water;
a semipermeable membrane treatment unit that uses a semipermeable membrane module having a first space and a second space separated by a semipermeable membrane and connected in multiple stages, that passes the first RO concentrate into the first space of the first stage semipermeable membrane module, that pressurizes the first space based on pressurization by the pressurizing unit to permeate the water contained in the first RO concentrate through the semipermeable membrane to obtain concentrate, that further uses the next and subsequent semipermeable membrane modules to obtain concentrate, and that passes a part of the first RO permeate or at least a part of the concentrate or at least a part of the diluent obtained from the other semipermeable membrane modules to the second space of each stage semipermeable membrane module to obtain diluent; and
and a flow rate adjustment means for measuring the flow rate of the concentrated water and the flow rate of the diluted water, and adjusting the flow rate of the first RO concentrated water supplied to the first space of the semipermeable membrane module of the first stage and the flow rate of the diluted water supplied to the second space of the semipermeable membrane module of the preceding stage of the final stage so that the measured value of the flow rate of the concentrated water of the final stage, the measured value of the flow rate of the diluted water of the first stage, and the measured value of the flow rate of the diluted water of the final stage become target flow rate values set in advance.
6. A water treatment apparatus according to claim 5, wherein,
the first reverse osmosis membrane has 0.2-0.7 m under the conditions that the effective pressure of the membrane surface is 1MPa and the temperature is 25 DEG C 3 /m 2 Pure water permeation flux in the range of/day, and has a characteristic that the NaCl removal rate at standard operating pressure is 99.5% or more, which is the NaCl removal rate at 32,000 mg/L.
7. A water treatment device according to claim 5 or 6, wherein,
the pressure of the first RO concentrated water immediately after the first RO membrane treatment unit is 7MPa or more, and the water treatment apparatus further includes a depressurizing unit depressurizing the first RO concentrated water to less than 7MPa at a stage preceding the semipermeable membrane treatment unit.
8. A water treatment device according to claim 5 or 6, wherein,
the water treatment apparatus further includes a second reverse osmosis membrane treatment unit that introduces the dilution water to a second reverse osmosis membrane to obtain second RO permeate water and second RO concentrate water.
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| CN105585077A (en) * | 2011-09-20 | 2016-05-18 | 三浦工业株式会社 | Reverse osmosis membrane separation device |
| JP2014140794A (en) * | 2013-01-22 | 2014-08-07 | Toray Ind Inc | Fresh water generator and fresh water generation metho |
| CN109843416A (en) * | 2016-08-30 | 2019-06-04 | 野村微科学股份有限公司 | The operation method of reverse osmosis membrane treatment system and reverse osmosis membrane treatment system |
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