TW201334858A - Method for generating fresh water and fresh water-generating apparatus - Google Patents

Abstract

The present invention provides a method for generating fresh water and a fresh water-generating apparatus, which can reduce cost of equipment, footprint of the apparatus, decrease abrasion of a membrane resulting from a flushing process, and efficiently clean a membrane module. The present invention relates to the method for generating fresh water and fresh water-generating apparatus for providing supplying raw water for the membrane module having a separation membrane to obtain membrane-percolated water, more specifically, to a method for cleaning the membrane module.

Description

Water production method and water generating device

The present invention relates to a water-making method and a water-making apparatus for supplying raw water to a membrane module having a separation membrane to obtain membrane-filtered water, and more particularly to a method for washing a membrane module.

The membrane separation method is widely used in various fields because of its energy saving, space saving, and improved filtration water quality. For example, precision membranes or ultrafiltration membranes are suitable for the treatment of industrial water or tap water from river water or groundwater or sewage treatment water, or for the treatment of seawater desalination reverse osmosis membrane treatment. The nanofiltration membrane or the reverse osmosis membrane is suitable for a highly water-purifying process, which is removed by mildew, chromaticity, hardness component, etc., which cannot be completely removed by a microfiltration membrane or an ultrafiltration membrane, or is suitable for desalination. , salt water desalination, pure water manufacturing, etc.

Continuous membrane filtration of raw water, with the membrane filtration water amount, the amount of membrane contaminants in suspended matter, humus, and proteins derived from microorganisms adheres to the surface of the separation membrane or the pores of the separation membrane gradually increases, and the filtration flow rate The problem of falling or membrane filtration differential pressure rises.

Then, the bubble is supplied to the separation membrane for one measurement (raw water side), the separation membrane is shaken and the separation membranes are brought into contact with each other to cause adhesion to the separation. The air on the surface of the film is scraped off by air cleaning, or the membrane filtered water or clean water is pressed from the secondary side of the separation membrane (membrane filtration water side) to the primary side of the separation membrane in the opposite direction to the filtration method of the membrane. The back pressure of the pollutants adhering to the surface of the separation membrane or the fine pores of the separation membrane is removed, and the high-flow raw water is circulated on the primary side of the membrane to increase the flow velocity of the membrane surface, and the shearing force of the water flow is adhered to the separation. Physical washing such as rinsing and washing of the contaminant on the surface of the film has been put into practical use.

Further, Patent Document 1 proposes a method of rinsing and washing with a gas-liquid mixed fluid while supplying air. On the other hand, it is reported in Patent Documents 2 and 3 that the use of a water aspirator as an air supply unit can reduce equipment costs, installation space, and electricity bills more than conventional air compressors or blowers.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 11-342320

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2008-207158

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2009-148673

However, as in Patent Documents 1 to 3, when the air is introduced into the raw water and washed by the gas-liquid mixed fluid, the raw water contains a high-hardness substance, and the high-hardness substance and the film are strongly rubbed against each other to cause the surface of the film to be damaged or The problem of film friction that becomes rough on the surface of the film.

In addition, as in Patent Documents 2 and 3, pumping with water is used. In the case of the machine as the air supply unit, when the raw water having a high suspended matter concentration is supplied to the water flow aspirator, there is a problem that the pipe in the water flow aspirator is blocked.

In addition, the raw water containing juveniles such as sea water or salt water is supplied. In the case of a water aspirator, there is a problem that the tubing attached to the water aspirator grows and blocks the pipeline in the water aspirator. In addition, the shellfish grown in the piping before the water aspirator are detached from the piping by the shearing force of the raw water, and the piping is blocked in the water aspirator.

Further, Patent Document 2 discloses a method of recovering the washing and draining of the gas-liquid mixed fluid, separating and removing the suspended matter, and washing while circulating. However, since the separation and removal device is required, the equipment cost is increased and a space is required.

Accordingly, an object of the present invention is to provide a water-making method and a water-making apparatus which do not cause a decrease in water recovery rate, which is equivalent to a conventional washing and cleaning apparatus having a separation and removal apparatus, which reduces equipment cost, installation space, and film reduction during rinsing. Friction, while also cleaning the membrane module efficiently.

In order to solve the above problems, the water making method and the water generating device of the present invention are as described in the following (1) to (11):

(1) A method for producing water, which comprises supplying raw water containing a high hardness substance having a hardness higher than that of a microfiltration membrane or an ultrafiltration membrane, to a precision filtration membrane module including the above-mentioned precision filtration membrane as a separation membrane or including the foregoing The ultrafiltration membrane is used as an ultrafiltration membrane module of the separation membrane to obtain membrane filtration water; and the water purification method for separating the membrane filtration water into the nanofiltration membrane module or the reverse osmosis membrane module to separate into the permeated water and the concentrated water . Its characteristics are: A water-making method for supplying a gas-liquid mixed fluid in which at least a part of the concentrated water is mixed into the air to the lower portion of the primary side of the separation membrane of the microfiltration membrane module or the ultrafiltration membrane module is performed for a period of time.

(2) A method for producing water, comprising: supplying raw water containing a high hardness substance having a hardness higher than that of a microfiltration membrane or an ultrafiltration membrane to a precision filtration membrane module including the above-mentioned precision filtration membrane as a separation membrane or The ultrafiltration membrane module including the foregoing ultrafiltration membrane as a separation membrane to obtain membrane filtration water; and a gas-liquid mixed fluid for mixing at least a part of the membrane filtration water into the air to supply the aforementioned microfiltration membrane or ultrafiltration membrane for a period of time The cleaning process of the lower part of the primary side of the separation membrane of the module.

(3) The method for producing water according to (1) or (2), wherein the mixing of the air is performed using a water aspirator.

(4) The method for producing water according to any one of (1) to (3), wherein the gas-liquid mixed fluid is supplied to the first side of the separation membrane of the microfiltration membrane module or the ultrafiltration membrane module. Before the lower portion, the water on the primary side of the separation membrane module or the separation membrane of the ultrafiltration membrane module is discharged to the outside of the system.

(5) The method for producing water according to any one of (1) to (4), wherein the gas-liquid mixed fluid is supplied to the lower portion of the primary side of the separation membrane of the microfiltration membrane module or the ultrafiltration membrane module. At least a part of the water discharged from the primary side of the separation membrane of the microfiltration membrane module or the ultrafiltration membrane module is collected and mixed into the raw water.

(6) The method for producing water according to any one of (1) to (5) wherein, in the back pressure washing, the membrane filtration water is filtered from the microfiltration membrane module or the ultrafiltration The separation membrane of the membrane module is sent to the separation membrane Primary side.

(7) The method for producing water according to (6), wherein the drug is added to the membrane-filtered water at the time of performing the back pressure washing.

(8) The method for producing water according to any one of (1) to (7) wherein the raw water contains a high hardness substance.

(9) A water generating device characterized by comprising: a fine filter membrane which filters raw water containing a high hardness substance having a hardness higher than that of a microfiltration membrane or an ultrafiltration membrane, and discharges membrane filtration water from a secondary side of the separation membrane The ultrafiltration membrane module comprises the above-mentioned precision membrane as a separation membrane, and the ultrafiltration membrane membrane comprises the ultrafiltration membrane as a separation membrane; a nanofiltration membrane module or a reverse osmosis membrane The module uses a nanofiltration membrane or a reverse osmosis membrane to separate the obtained membrane filtration water into permeate water or concentrated water; the concentrated water return unit is used for the above-mentioned nanofiltration membrane module or reverse osmosis membrane module. At least a part of the discharged concentrated water is supplied to the lower portion of the primary side of the separation membrane of the microfiltration membrane module or the ultrafiltration membrane module, and an air mixing unit in which the concentrated water in the concentrated water return unit is mixed with air.

(10) A water generating device characterized by comprising: a microfiltration membrane module or an ultrafiltration membrane module, and filtering raw water containing a high hardness substance having a hardness higher than that of a microfiltration membrane or an ultrafiltration membrane from a separation membrane The microfiltration membrane module or the ultrafiltration membrane module for discharging the membrane on the secondary side, wherein the microfiltration membrane module comprises the above-mentioned microfiltration membrane as a separation membrane, and the ultrafiltration membrane membrane system comprises the ultrafiltration membrane as the separation. membrane; a membrane filtered water return unit for supplying at least a portion of the obtained membrane filtered water to a lower portion of the primary side of the separation membrane module or the separation membrane of the ultrafiltration membrane module; and an air mixing unit The membrane filtered water in the membrane filtered water return unit is mixed with air.

(11) The water generating device according to (9) or (10), wherein the air mixing unit is a water flow aspirator.

Compared with the conventional washing and separating device, the present invention can reduce the equipment cost, the installation space, and reduce the film friction, and can also clean the film module efficiently. Further, in the case where the water flow aspirator is used as the air supply unit, the clogging of the piping in the water flow aspirator is not caused, and the operation maintenance management is easy.

1‧‧‧ raw water storage tank

2‧‧‧ Raw water supply pump

3‧‧‧Water valve

4‧‧‧Precision filter/ultrafiltration membrane module

5‧‧‧Filter water valve

6‧‧‧Precision filter / ultrafiltration membrane filtered water storage tank

7‧‧‧Backwash pump

8‧‧‧Backwash valve

9‧‧‧Pharmaceutical supply pump A

10‧‧‧Pharmaceutical storage tank A

11‧‧‧Nano filter/reverse osmosis membrane module

12‧‧‧High pressure pump

13‧‧‧Nano filter/reverse osmosis membrane supply water valve

14‧‧‧Nano filter/reverse osmosis membrane concentrate valve

15‧‧‧Concentrated water return valve

16‧‧‧Water aspirator

17‧‧‧Check valve

18‧‧‧Drain valve

19‧‧‧Degas valve

20‧‧‧Recycling tank

21‧‧‧Pharmaceutical supply pump B

22‧‧‧Pharmaceutical storage tank B

23‧‧‧ membrane filtered water return valve

24‧‧‧Air wash valve

25‧‧‧Blowing pump

Fig. 1 is a schematic flow chart showing an apparatus of an example of a fresh water generator to which the first embodiment of the present invention is applied.

Fig. 2 is a schematic flow chart showing an apparatus of another example of the fresh water generator to which the first embodiment of the present invention is applied.

Fig. 3 is a schematic flow chart showing an apparatus of an example of a fresh water generator to which the second embodiment of the present invention is applied.

Fig. 4 is a schematic flow chart showing an example of a conventional water generator.

[Formation of the Invention] (First embodiment)

Hereinafter, a first embodiment of the present invention will be described based on the embodiment shown in the drawings. Further, the present invention is not limited to the following embodiments.

In the present invention, as shown in Fig. 1, there is provided a raw water storage tank 1 for storing raw water, a raw water supply pump 2 for supplying raw water, and a raw water valve 3, It is opened when the raw water is supplied, the precision filter membrane/ultrafiltration membrane module 4 is used to filter the raw water; the filtered water valve 5 is opened during the membrane filtration; the precision membrane/ultramembrane filtered water storage tank 6 is The membrane filtration water obtained by the precision membrane/ultrafiltration membrane module 4 is stored; the backwashing pump 7 is operated when the membrane filtration water is supplied to the precision membrane/ultrafiltration membrane module 4 for back pressure washing; The washing valve 8 is opened when the back pressure is cleaned; the medicine supply pump A9 is operated when the back pressure washing water is added with the medicine; the medicine storage tank A10 is for storing the medicine; the nanofiltration membrane/reverse osmosis membrane module 11 The membrane filtration water is separated into permeate water/concentrated water; the high pressure pump 12 supplies the membrane filtration water to the nanofiltration membrane/reverse osmosis membrane module 11; the nanofiltration membrane/reverse osmosis membrane supply water valve 13, open when the membrane filtration water is supplied to the nanofiltration membrane/reverse osmosis membrane module 11; the nanofiltration membrane/reverse osmosis membrane concentrated water valve 14; concentrated water back The valve 15 is opened when the gas-liquid mixed fluid is supplied to the lower portion of the primary side of the separation membrane of the precision membrane/ultrafiltration membrane module 4; the water aspirator 16 is mixed as air mixed with the concentrated water in the air. The check valve 17 prevents the raw water from flowing backward; the drain valve 18 is opened when the water on the primary side of the separation membrane of the precision membrane/ultrafiltration membrane module 4 is discharged from the lower portion; the deaeration valve 19 is The air or water on the primary side of the separation membrane of the precision membrane/ultrafiltration membrane module 4 is opened from above; the recovery tank 20 is degassed from above the precision membrane/ultrafiltration membrane module 4 The water discharged from the valve 19 is recovered; the drug supply pump B21 is attached to the precision filter membrane/super The concentrated water fed back by the membrane module 4 is operated when the medicine is added; and the medicine storage tank B22 is used for storing the medicine.

In the above-described water generating device, the usual filtering process operates the raw water supply pump 2 in a state where the raw water valve 3 is opened, whereby the raw water stored in the raw water storage tank 1 is supplied to the fine filter/ultrafiltration membrane module. The lower portion of the primary side of the separation membrane of the group 4 is opened, and the filtration water valve 5 is opened to carry out pressure filtration of the microfiltration membrane/ultrafiltration membrane module 4. The membrane filtered water is sent from the secondary side of the separation membrane through the filtration water valve 5 to the precision filtration membrane/ultrafiltration membrane filtered water storage tank 6. In the case of full-capacity filtration, the backwash valve 8, the concentrated water return valve 15, the drain valve 18, and the deaeration valve 19 are all closed.

The filtration time of the precision membrane/ultrafiltration membrane module 4 is preferably set according to the raw water quality or membrane filtration flux, but it can also be used in the case of constant flow filtration, in the predetermined membrane filtration differential pressure or membrane filtration. In the case of the water amount [m ³ ], the filtration time is continued until a predetermined membrane filtration flow rate [m ³ /day] or membrane filtration water amount [m ³ ] is reached. Further, the membrane filtration flow rate refers to the amount of membrane filtration water per unit time.

The membrane filtered water stored in the membrane filtered water storage tank 6 is opened by operating the high pressure pump 12 and the nanofiltration membrane/reverse osmosis membrane supply water valve 13 is supplied to the nanofiltration membrane/reverse osmosis membrane module 11 for crossover. Flow filtering. At this time, the nanofiltration membrane/reverse osmosis membrane concentration water valve 14 is opened, and the concentrated water return valve 15 is closed. The ratio of the membrane permeate flow rate and the concentrated water flow rate of the nanofiltration membrane/reverse osmosis membrane module 11 is desirably determined according to the precision filtration membrane/ultrafiltration membrane filtration water, that is, the water quality of the nanofiltration membrane/reverse osmosis membrane module supply water. Make appropriate settings.

In the water generating device as described above, the cleaning method of the microfiltration membrane/ultrafiltration membrane module 4 of the water generating method of the present invention is as follows, for example, Shi.

First, the raw water valve 3 and the filtered water valve 5 are closed, and the raw water supply pump 2 is stopped to stop the filtration process of the fine filter/ultrafiltration membrane module 4. Then, the drain valve 18 and the deaeration valve 19 are opened, and the water on the primary side of the separation membrane of the microfiltration membrane/ultrafiltration membrane module 4 is passed from the lower portion of the primary side of the separation membrane of the microfiltration membrane/ultrafiltration membrane module 4. When the drain valve 15 is discharged to the outside of the system, the water level in the microfiltration membrane/ultrafiltration membrane module 4 is gradually lowered, and the state around the primary side of the separation membrane becomes a gas state. Here, the primary side of the separation membrane means the side to which the raw water to be filtered is supplied, and the secondary side of the separation membrane means the side where the membrane-filtered water obtained by filtering the raw water by the membrane is present. In this manner, after the full-capacity water on the primary side of the separation membrane of the precision membrane/ultrafiltration membrane module 4 is discharged, the drain valve 18 is closed and the concentrated water return valve 15 is opened, and the concentrated water passes through the water aspirator 16 Automatically mix with air. The gas-liquid mixed fluid of concentrated water and air is supplied to the lower portion of the primary side of the separation membrane of the fine membrane/ultrafiltration membrane module 4 through the check valve 17.

The water flow aspirator 16 is a T-shaped tube, and one end of the T-shaped tube corresponding to the horizontal line is connected to the concentrated water side of the nanofiltration membrane/reverse osmosis membrane 11 and the other end is connected to the precision filtration membrane/ultrafiltration membrane module. 4 sides. The tube corresponding to the vertical line in the T type serves as an air suction port. The inner part of the tube equivalent to the horizontal line is thinned, from which the tube corresponding to the vertical line is connected. When the water is caused to flow in the horizontal direction, the flow velocity is increased in the portion where the tube is tapered, so that the pressure is lowered by the Venturi effect. Air is drawn into this reduced pressure water stream.

In the case of the air mixing unit, in addition to the water aspirator, air can be supplied by a blower or a compressor, but the water aspirator Compared with a blower or a compressor, it is preferable to reduce equipment cost, installation space, and electricity cost.

Further, in the case where the discharge pressure of the high pressure pump 12 such as seawater desalination is high, it is preferable to measure the withstand voltage performance of the water flow aspirator 12 and to control the discharge pressure with a frequency converter or the like.

As a result, bubbles are supplied while moving the water level in the fine filter/ultrafiltration membrane module 4 upward, and the contaminant adhering to the surface of the separation membrane is effectively peeled off. In addition, the water level in the ultrafiltration membrane/ultrafiltration membrane module 4 reaches an upper limit, and the gas-liquid mixed fluid is separated from the pollutants peeled off from the surface of the separation membrane from the side of the upper side of the microfiltration membrane/ultrafiltration membrane module 4. The nozzle is discharged through the deaeration valve 19 to the outside of the system.

At this time, in order to further improve the washing effect, it is preferable to drive the medicine supply pump B21 to add the medicine in the shrinkage water to the medicine storage tank B22.

The larger the concentrated water flow rate supplied to the water flow aspirator 16, the larger the air flow rate of the suction air flow extractor 16 is, and the contaminant adhering to the surface of the separation membrane is peeled off and discharged to the precision filter membrane/ultrafiltration membrane module. The larger the effect outside the system of 4, the better, but it is appropriately set within a range that does not cause damage of the separation membrane. In the case of the concentrated water flow rate: the mixing ratio of the air flow rate, the peeling effect of the pollutants is preferably from 1:1 to 5:1.

By the discharge pressure from the water flow aspirator 16 during the above washing, although the filtration flow rate is smaller than that of the general filtration process, the gas-liquid mixed fluid discharged from the water flow aspirator 16 can be opened while the filtration water valve 5 is opened. The lower part of the primary side of the separation membrane supplied to the precision membrane/ultrafiltration membrane module 4 The washing process is filtered on one side. The separation membrane can be washed and filtered simultaneously.

Further, the backwash valve 8 is opened and the backwash pump 7 is operated, whereby the back pressure washing of the membrane filtered water in the fine filter membrane/ultramembrane filtered water storage tank 6 is combined and combined, thereby The effect of peeling off the contaminant on the surface of the separation membrane and discharging it to the system of the ultrafiltration membrane/ultrafiltration membrane module 4 is large, so that it is preferable.

Back pressure washing can also be carried out before and/or after, and/or simultaneously with, flushing with the gas-liquid mixed fluid. However, based on the viewpoint of reducing the friction of the film caused by the high-hardness substance, the back pressure washing is performed before the washing with the gas-liquid mixed fluid, and the suspended matter is as much as possible from the film module before washing with the gas-liquid mixed fluid. Pre-discharge is preferred.

In the case of back pressure washing before flushing with the gas-liquid mixed fluid, the deaeration valve 19 and the exhaust valve 18 are opened, and the water on the primary side of the separation membrane of the precision membrane/ultrafiltration membrane module 4 is finely filtered. The lower portion of the primary side of the separation membrane of the membrane/ultrafiltration membrane module 4 is discharged to the outside of the system through the drain valve 18, and the drain valve 18 is kept open while the primary side of the separation membrane becomes air, and the backwash valve 8 is opened and operated. The backwash pump 7 is preferred. Since the resistance caused by the water pressure at the time of back pressure washing is eliminated, the suspended matter adhering to the surface of the separation membrane is easily peeled off, and the separated suspended matter is detached from the surface of the separation membrane, and is not retained between the separation membrane and the separation membrane. The lower portion of the primary side of the separation membrane of the membrane/ultrafiltration membrane module 4 is discharged outside the system through the drain valve 18. Then, to perform the cleaning of the gas-liquid mixed fluid, the backwash valve 8 is closed, the backwashing pump 7 is stopped, the drain valve 18 is closed, and the concentrated water return valve 15 is opened.

In addition, when the gas-liquid mixed fluid is supplied to the lower portion of the primary side of the separation membrane of the fine membrane/ultrafiltration membrane module 4 while being back-pressure washed, the backwash valve 8 is closed in a state where the drain valve 18 is closed. The concentrated water return valve 15 and the deaeration valve 19 are opened, and the backwash pump 7 is preferably operated.

In the method of improving the washing effect of the back pressure washing, it is preferable to operate the medicine supply pump A9 and to apply the medicine in the membrane filtration water-added medicine storage tank A10 used for back pressure washing.

Although the higher the flow rate of the back pressure washing, the effect of the separation of the suspended matter from the surface of the separation membrane is greater, but there is a case where the flow rate is excessively generated and the back pressure is generated on the primary side of the separation membrane, which hinders the separation of the suspended matter from the surface of the separation membrane. Therefore, it is preferable to appropriately control the flow rate of the back pressure washing in accordance with the configuration of the fine membrane/ultrafiltration membrane module 4 or the flow rate of the gas-liquid mixed fluid.

In order to increase the water recovery rate, at least a portion of the gas-liquid mixed fluid discharged from the side nozzle of the upper portion of the fine membrane/ultrafiltration membrane module 4 through the deaeration valve 19 to the outside of the system is peeled off from the surface of the separation membrane. After the pollutants flow into the recovery tank 20 together, it is preferably returned to the primary side of the separation membrane of the fine membrane/ultrafiltration membrane module 4 of the raw water storage tank 1. As described above, the drug may be added to the membrane-filtered water used for the back pressure washing. However, when the drug is added at a high concentration, it is preferably returned to the raw water storage tank 1 after the chemical treatment of the neutralization treatment.

Then, the backwash valve 8 and the concentrated water return valve 15 are closed, the backwashing pump 7 is stopped, the washing of the gas-liquid mixed fluid or the back pressure washing is stopped, and the drain valve 18 is once opened, and the fine filter/ultrafiltration is performed. After the full capacity of the water on the primary side of the separation membrane of the membrane module 4 is discharged to the outside of the system, the drain valve 8 is closed, the raw water valve 3 is opened, and the raw water supply pump 2 is operated to make the microfiltration membrane/ultrafiltration membrane module. The separation membrane of Group 4 may be filled with raw water on one side, or may be discharged in a small amount. The raw water valve 3 is directly opened, and the raw water supply pump 2 is operated to fill the separation membrane of the precision membrane/UF membrane module 4 at one time. unboiled water.

After the separation membrane of the precision membrane/ultrafiltration membrane module 4 is filled with water on one side, the filtration valve 5 is opened and the deaeration valve 16 is closed, and then the filtration process of the microfiltration membrane/ultrafiltration membrane module 4 can be returned. , repeat the above process to continue to build water.

In the case of the microfiltration membrane/ultrafiltration membrane module 4, the external pressure type or the internal pressure type are not impeded, but the washing effect of the present invention is easy to exert due to the high flow rate of the gas-liquid mixed fluid in contact with the surface of the separation membrane. Therefore, the internal pressure type is preferred. Further, in terms of the membrane filtration method, the full-capacity filtration membrane module or the cross-flow filtration membrane module is not harmful, but the full-capacity filtration membrane module is preferable because of the low energy consumption. Further, the pressurized film module or the immersed film module is not harmful, but a pressurized film module is preferable because it can be operated with high-flux filtration. In the case of the shape of the pressurized membrane/ultrafiltration membrane module 4, in the case of a pressurized membrane module, a hollow fiber membrane or a tubular membrane or a monolith is accommodated in a pressurized container of a cylinder or a rectangular parallelepiped. In the membrane module such as a membrane, the position of the raw water supply port is the lower bottom surface or the lower side surface of the membrane module, and the separation membrane is longitudinally disposed to obtain the membrane filtration water from the upper portion of the membrane module. In the case of the immersed membrane module, for example, as in Fig. 2, in order to allow the gas-liquid mixed fluid discharged from the water flow aspirator 16 to contact the entire membrane surface of the microfiltration membrane/ultrafiltration membrane module 4, from the precision filtration When a gas-liquid mixed fluid is supplied under the membrane/ultrafiltration membrane module 4, a cylinder, a rectangular parallelepiped or a sheet type may be used, and the outlet position of the membrane filtered water may be any position.

Further, an organic or inorganic coagulant or powder activated carbon may be added to the raw water supplied to the lower portion of the primary side of the separation membrane of the ultrafiltration membrane/ultrafiltration membrane module 4. The effect of suppressing membrane fouling or reducing the concentration of organic matter in membrane filtration by adding a coagulant. As the organic coagulant, a dimethylamine-based or polyacrylamide-based positive ion polymer coagulant can be used. On the other hand, as the inorganic coagulant, polyaluminum chloride, polyaluminum sulfate, ferric chloride, polyferric sulfate, ferric sulfate, polyferric oxide iron can be used. Wait. The dissolved organic matter can be adsorbed and removed by adding powdered activated carbon.

The separation membrane used in the microfiltration membrane/ultrafiltration membrane module 4 is not particularly limited as long as it is porous, and a microfiltration membrane may be used depending on the water quality or amount of water to be treated. Use an ultrafiltration membrane or use both. For example, in the case of removing a dirty component, a coliform, a Cryptosporidium, or the like, any of a precision membrane or an ultrafiltration membrane may be used, but in the case where a virus or a polymer organic substance is also to be removed, an ultrafiltration membrane is used. Preferably.

Regarding the shape of the separation membrane, there may be any one of a hollow fiber membrane, a flat membrane, a tubular membrane, and the like.

The material of the separation membrane contains polyethylene, polypropylene, polyacrylonitrile, ethylene-tetrafluoroethylene copolymer, polychlorotrifluoroethylene, polytetrafluoroethylene, polyvinyl fluoride, tetrafluoroethylene-hexafluoropropylene. Copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and chlorotrifluoroethylene-ethylene copolymer, polyvinylidene fluoride (PVDF), polyfluorene (PSF), cellulose acetate, polyvinyl alcohol Selected groups of (PVA) and polyether (PES) At least one of them is preferred, and further, polyvinylidene fluoride (PVDF) based on film strength or chemical resistance is more preferable, and polyacrylonitrile having high hydrophilicity and high stain resistance is more preferable.

For the control method of the filtration operation, both the constant flow filtration and the constant pressure filtration can be used, but the constant flow filtration is preferable based on the point that a certain amount of treated water is obtained and the whole is easy to control.

The agent added to the membrane-filtered water used for rinsing and washing with the gas-liquid mixed fluid and the membrane-filtered water used for backwashing can be selected with appropriate settings for the concentration and retention time of the film which is not deteriorated, but Since at least one of sodium hypochlorite, chlorine dioxide, chloramine, hydrogen peroxide, ozone, and the like is contained, the effect of washing the organic substance is large, which is preferable. Further, since at least one of hydrochloric acid, sulfuric acid, nitric acid, citric acid, oxalic acid, and the like is contained, the cleaning effect on aluminum, iron, manganese, and the like is large, which is preferable.

In particular, a chlorine-based bactericide such as sodium hypochlorite is more effective and has a lower residual property.

Further, the agent added to the membrane-filtered water used for the back pressure washing may be the same as or different from the agent added to the concentrated water used for washing and washing with the gas-liquid mixed fluid.

Further, in the case of adding a drug, it is not always necessary to add a drug to the backwash water every time the drug is washed, and it is possible to effectively reduce the amount of the drug to be used by adding the drug once a few times for washing.

For the nanofiltration membrane/reverse osmosis membrane used in the nanofiltration membrane/reverse osmosis membrane module 11, let a part of the separated mixture, for example, let the solvent penetrate without infiltrating other components. A translucent separation membrane that is substantially reversibly permeable and separated, and a dechlorination rate of the nanofiltration membrane It is defined as 5% or more and less than 93% (evaluation conditions are NaCl concentration: 500 mg/l, operating pressure: 0.1 MPa), and the dechlorination rate of the reverse osmosis membrane is defined as 93% or more (evaluation conditions are NaCl concentration: 500 mg/l, Operating pressure: 0.1 MPa). The nanofiltration membrane/reverse osmosis membrane may be appropriately selected depending on the quality of the membrane filtration water required or the purpose of application. As the material, a polymer material such as a cellulose acetate polymer, a polyamide, a polyester, a polyimide, or a vinyl polymer can be used. Further, the separation membrane is configured with an asymmetric separation membrane and a composite separation membrane having a dense layer on at least one side of the separation membrane, and having fine pores which gradually increase the pore diameter from the dense layer toward the inside of the separation membrane or the other surface; The composite separation membrane has a very thin separation functional layer formed of another material on the dense layer of the asymmetric separation membrane. The separation membrane morphology includes a hollow fiber membrane and a flat membrane. The present invention can be carried out without depending on such a separation membrane material, a separation membrane structure or a separation membrane form, and any one of them has an effect, and a representative separation membrane includes an asymmetric separation having, for example, cellulose acetate or polyamine. A membrane and a composite separation membrane having a separation functional layer of a polyamidamide-based or polyurea-based membrane, and a cellulose acetate-based asymmetric separation membrane or a polyamine-based catalyst are used from the viewpoints of water production amount, durability, and chlorine discharge rate. A composite separation membrane is preferred.

A nanofiltration membrane/reverse osmosis membrane having such a performance is assembled into a spiral, a cylindrical, a plate-and-frame type element in order to be used in practice, and the hollow fiber membrane is bundled and assembled in a component to be used. However, the present invention is not affected by such reverse osmosis membrane elements.

In addition, in the present invention, the nanofiltration membrane/reverse osmosis membrane module 11 is of course a module for arranging the aforementioned nanofiltration membrane/reverse osmosis membrane element in one to several containers, and further comprises a plurality of modules. Modules arranged side by side. The combination, the number, and the arrangement can be arbitrarily performed according to the purpose. The shape of the nanofiltration membrane/reverse osmosis membrane module 11 is a spiral type element in which a flat membrane is collected in a cylindrical shape or a hollow fiber membrane in which a hollow fiber membrane is aggregated in a cylindrical shape. The module is housed in a pressurized container of the cylinder.

According to the cleaning method of the microfiltration membrane/ultrafiltration membrane module of the above-described water-making method of the present invention, the first effect is that the high-hardness substance in the raw water is captured by the microfiltration membrane/ultrafiltration membrane, and is not contained in the washing. The net concentrated water or membrane filtered water can reduce the degree of membrane friction during washing with the gas-liquid mixed fluid. Further, the high-hardness substance peeled off from the film when rinsing with the gas-liquid mixed fluid is discharged from the upper portion of the fine filter/ultrafiltration membrane module 4 by the gas-liquid mixed fluid, so that the influence on the friction of the film is small.

When the air is mixed by a water aspirator, the second effect is that the concentrated water or membrane filtered water used for washing does not contain suspended substances, so that the piping of the water flow aspirator is not blocked, and the operation is easy to manage. . Even if it is raw water containing larvae such as seawater or salt water, the larvae are easily captured by the precision membrane/ultrafiltration membrane module, and are not contained in the concentrated water or membrane filtration water used for washing, so it does not cause The pipeline in the water aspirator is blocked. Therefore, it is particularly effective for raw water containing juveniles such as raw water having a high suspended matter concentration or seawater or salt water.

Here, the high hardness substance means a particle which is harder than the separation membrane of the microfiltration membrane/ultrafiltration membrane module. Examples of such a high-hardness material include powdered activated carbon, metal powder, silt particles, sand, and ceramic particles, and pulverized materials of juveniles and shellfish.

Here, the measurement method for determining whether the high hardness substance is harder than the filtration membrane is utilized in ISO 14577-1:2002 (instrumentation pressure) The trace hardness is measured based on the measurement method, and the measured hardness is compared and determined. However, in the case where the separation membrane was a hollow membrane, the membrane was cut into a flat membrane.

Further, in the case where the concentrated water outside the drainage discharge system is reused, the water recovery rate is not lowered.

(Second embodiment)

Hereinafter, the fresh water generator to which the second embodiment of the present invention is applied is shown in Fig. 3. In addition, the description of the place where the first embodiment is repeated will be omitted.

The present embodiment differs from the first embodiment in that the membrane-filtered water using the microfiltration membrane/ultrafiltration membrane module 4 is used as the water for washing the gas-liquid mixed fluid for the microfiltration membrane/ultrafiltration membrane module 4.

In the second embodiment, the cleaning method of the microfiltration membrane/ultrafiltration membrane module 4 is carried out, for example, as described below.

First, the raw water valve 3 and the filtered water valve 5 are closed, the raw water supply pump 2 is stopped, and the filtration process of the microfiltration membrane/ultrafiltration membrane module 4 is stopped. Then, the drain valve 18 and the deaeration valve 19 are opened, and the lower portion of the primary side of the separation membrane of the precision membrane/ultrafiltration membrane module 4 is discharged to the outside of the system through the drain valve 18, and the precision membrane/ultrafiltration membrane module 4 The water level in the interior gradually decreases, forming a state in which the gas around the primary side of the separation membrane becomes gas. After the full-capacity water discharge of the primary side of the separation membrane of the ultrafiltration membrane module 4 is closed, the drain valve 18 is closed and the membrane filtered water return valve 23 is opened to operate the backwash pump 7, and the membrane filtered water is pumped through the water flow. The machine 16 is automatically mixed with air. The gas-liquid mixed fluid of the membrane-filtered water and the air is supplied to the lower portion of the primary side of the separation membrane of the fine membrane/ultrafiltration membrane module 4 through the check valve 17.

The gas-liquid mixed fluid is supplied to the lower portion of the primary side of the separation membrane of the fine membrane/ultrafiltration membrane module 4 before and/or after and/or at the same time, the backwash valve 8 is opened, and the backwash pump 7 is operated, thereby using The membrane filtration water in the ultrafiltration membrane/ultrafiltration membrane filtered water storage tank 6 is backwashed, so that the pollutants are peeled off from the surface of the separation membrane and discharged to the outside of the system of the microfiltration membrane/ultrafiltration membrane module 4. The effect is larger, so it is better.

Then, the backwash valve 8 and the membrane filtered water return valve 23 are closed, the backwashing pump 7 is stopped, the washing of the gas-liquid mixed fluid or the back pressure washing is stopped, and the drain valve 18 is once opened, and the precision filter/ultrafiltration is performed. After the full-capacity water on the primary side of the separation membrane of the membrane module 4 is discharged to the outside of the system, the drain valve 18 is closed, the raw water valve 3 is opened, and the raw water supply pump 2 is operated to fill the raw water with the fine membrane/ultrafiltration membrane. The separation membrane of the module 4 may also be on the primary side, or may not be fully drained, directly open the raw water valve 3, and operate the raw water supply pump 2 to fill the separation membrane of the precision membrane/ultrafiltration membrane module 4 with raw water. side.

After the separation membrane of the precision membrane/ultrafiltration membrane module 4 is filled with water on one side, the filtration water valve 5 is opened, and when the deaeration valve 19 is closed, the filtration process of the microfiltration membrane/ultrafiltration membrane module 4 is returned. By repeating the above process, water can be continuously produced.

[Examples] (Example 1)

As shown in Fig. 1, a hollow fiber ultrafiltration membrane made of TORAY (polypropylene) having a molecular weight cut off of 150,000 Da was placed side by side in the vertical direction with a total length of 2 m and a membrane area of 11.5 m ² . Five pressurized membrane modules were passed through the river with a membrane filtration flux of 2 m ³ /m ² /day. Two pieces of reverse osmosis membrane element (TML 10F) made of TORAY (manufactured by TORAY) with a total length of 1 m and a membrane area of 8 m ² are placed in a pressure vessel in a horizontal direction in a nanofiltration membrane/reverse osmosis membrane module. 11. The membrane filtration flow rate was 20 m ³ /day, the concentrated water flow rate was 20 m ³ /day, and the water recovery rate was 50%, and the ultrafiltration membrane was filtered through a cross-flow filtration membrane. The average turbidity of the river water is 40 NTU (Nephelometric Turbidity Unit) mixed with gravel.

After the fine filter/ultrafiltration membrane module 4 is filtered for 30 minutes, the full-capacity water amount on the primary side of the separation membrane in the precision membrane/ultrafiltration membrane module 4 is discharged, and the drain valve 18 and the deaeration valve 19 are opened. In the state, a back pressure of 2.5 m ³ /m ² /day and a sodium chloride aqueous solution having a chlorine concentration of 10 mg/l was subjected to back pressure washing for 1 minute. Then, the gas-liquid mixed fluid of concentrated water and air was washed for 1 minute. The mixing of the air is carried out by the water aspirator 16, when the flow rate of the concentrated water is controlled at 20 L/min per membrane module, and the suction flow rate of the air from the water aspirator 16 is controlled at 14 L/min per membrane module. Then, after the washing of the gas-liquid mixed fluid is stopped, the full-capacity water in the microfiltration membrane/ultrafiltration membrane module 4 is discharged to the outside of the system. Then, the raw water supply pump 2 is operated, and the raw water is supplied to the precision membrane/ultrafiltration membrane module 4, and then returned to the filtration process, and the above process is repeated.

As a result, the membrane filtration differential pressure of the microfiltration membrane/ultrafiltration membrane module 4 immediately after the start of operation is 25 kPa, and the operation can be stably performed at 58 kPa after one year, and one precision filtration membrane/ultrafiltration is performed one year later. The membrane module 4 was disassembled, and the outer surface of the membrane was observed with an electron microscope, and it was confirmed that about 90% of the outer surface of the membrane still had a smooth surface.

(Comparative Example 1)

As shown in Fig. 4, the same raw water as in Example 1 was filtered under the same membrane module and operating conditions as in Example 1.

After the fine filtration membrane/ultrafiltration membrane module 4 was filtered for 30 minutes, the same back pressure washing as in Example 1 was carried out. Then, the backwash valve 8 is closed, the backwashing pump 7, the drug supply pump 9 is stopped, the drain valve 18 is closed, the raw water valve 3, the air washing valve 24 is opened, the raw water supply pump 2 is operated, and the blow pump 25 is blown. The cleaning of the gas-liquid mixed fluid of raw water and air was carried out for 1 minute. At this time, the raw water flow rate is controlled at 20 L/min per module, and the air supply flow rate is controlled at 14 L/min per membrane module. Then, after the washing of the gas-liquid mixed fluid is stopped, the full-capacity water in the microfiltration membrane/ultrafiltration membrane module 4 is discharged to the outside of the system. Then, the raw water supply pump 2 is operated, and the raw water is supplied to the precision membrane/ultrafiltration membrane module 4, and then returned to the filtration process, and the above process is repeated.

As a result, the membrane filtration differential pressure of the microfiltration membrane/ultrafiltration membrane module 4 immediately after the start of operation was 25 kPa, and reached 90 kPa after one year. One year later, a precision filter/ultrafiltration membrane module 4 was disassembled, and the outer surface of the membrane was observed by an electron microscope. Only the outer surface of the membrane was smoothed, and the pores of the membrane were mostly destroyed or roughened.

The present invention has been described in detail with reference to the specific embodiments thereof. It is obvious that various changes or modifications may be made without departing from the spirit and scope of the invention.

The present application is based on Japanese Patent Application No. 2012-011727, filed on Jan.

1‧‧‧ raw water storage tank

2‧‧‧ Raw water supply pump

3‧‧‧Water valve

4‧‧‧Precision filter/ultrafiltration membrane module

5‧‧‧Filter water valve

6‧‧‧Precision filter / ultrafiltration membrane filtered water storage tank

7‧‧‧Backwash pump

8‧‧‧Backwash valve

9‧‧‧Pharmaceutical supply pump A

10‧‧‧Pharmaceutical storage tank A

11‧‧‧Nano filter/reverse osmosis membrane module

12‧‧‧High pressure pump

13‧‧‧Nano filter/reverse osmosis membrane supply water valve

14‧‧‧Nano filter/reverse osmosis membrane concentrate valve

15‧‧‧Concentrated water return valve

16‧‧‧Water aspirator

17‧‧‧Check valve

18‧‧‧Drain valve

19‧‧‧Degas valve

20‧‧‧Recycling tank

21‧‧‧Pharmaceutical supply pump B

22‧‧‧Pharmaceutical storage tank B

Claims (11)

A method for producing water includes supplying raw water containing a high hardness substance having a hardness higher than that of a microfiltration membrane or an ultrafiltration membrane to a precision filtration membrane module including the above-mentioned precision filtration membrane as a separation membrane or including the foregoing ultrafiltration membrane As an ultrafiltration membrane module of a separation membrane, a membrane filtration water is obtained; and the membrane filtration water is supplied to a nanofiltration membrane module or a reverse osmosis membrane module to separate into a water-forming method of permeating water and concentrated water, and the characteristics thereof The cleaning process includes supplying a gas-liquid mixed fluid in which at least a part of the concentrated water is mixed into the lower portion of the primary side of the separation membrane of the microfiltration membrane module or the ultrafiltration membrane module. A method for producing water, which comprises: supplying raw water containing a high hardness substance having a hardness higher than that of a precision filter membrane or an ultrafiltration membrane to a precision membrane module including the aforementioned precision membrane as a separation membrane or including the aforementioned super The filter membrane is used as an ultrafiltration membrane module of the separation membrane to obtain membrane filtration water; and a gas-liquid mixed fluid in which at least a part of the membrane filtration water is mixed into the air is supplied to the precision filter membrane or the ultrafiltration membrane module for a period of time. The cleaning process of the lower portion of the primary side of the separation membrane. The method of producing water according to claim 1 or 2, wherein the mixing of the air is performed using a water aspirator. The method for producing water according to any one of claims 1 to 3, wherein the gas-liquid mixed fluid is supplied to the lower portion of the primary side of the separation membrane of the microfiltration membrane module or the ultrafiltration membrane module. The water on the primary side of the separation membrane module or the separation membrane of the ultrafiltration membrane module is discharged to the outside of the system. The method for producing water according to any one of claims 1 to 4, wherein the gas-liquid mixed fluid is supplied to the lower portion of the primary side of the separation membrane of the microfiltration membrane module or the ultrafiltration membrane module, and is recovered. At least a part of the water discharged from the primary side of the separation membrane of the microfiltration membrane module or the ultrafiltration membrane module is mixed into the raw water. The method for producing water according to any one of claims 1 to 5, wherein the back pressure washing is performed, and the back pressure washing is performed by using the membrane filtration water from the microfiltration membrane module or the ultrafiltration membrane module. The secondary side of the separation membrane of the group was sent to the primary side of the separation membrane. The method for producing water according to claim 6, wherein the membrane-filtered water is added to the reagent during the back pressure washing. The method for producing water according to any one of claims 1 to 7, wherein the raw water contains a high hardness substance. A water generating device characterized by having a filter membrane module or a super filter that filters a raw water containing a high hardness material having a hardness higher than that of a microfiltration membrane or an ultrafiltration membrane and discharges the membrane filtration water from the secondary side of the separation membrane. The filter module, the precision filter module comprises the above-mentioned precision filter membrane as a separation membrane, and the ultrafiltration membrane membrane group comprises the ultrafiltration membrane as a separation membrane; a nanofiltration membrane module or a reverse osmosis membrane module, The obtained membrane filtered water is separated into permeated water or concentrated water by using a nanofiltration membrane or a reverse osmosis membrane; and the concentrated water returning unit is used for concentrating the nanofiltration membrane module or the reverse osmosis membrane module. At least a portion of the water is supplied to the lower portion of the primary side of the separation membrane module or the separation membrane of the ultrafiltration membrane module; In the air mixing unit, the concentrated water in the concentrated water return unit is mixed with air. A water generating device characterized by having a filter membrane module or a super filter that filters a raw water containing a high hardness material having a hardness higher than that of a microfiltration membrane or an ultrafiltration membrane and discharges the membrane filtration water from the secondary side of the separation membrane. The membrane module, the microfiltration membrane module comprises the above-mentioned precision membrane as a separation membrane, the ultrafiltration membrane membrane system comprises the ultrafiltration membrane as a separation membrane, and the membrane filtration water return unit is used for obtaining the membrane module. At least a portion of the membrane filtered water is supplied to the lower portion of the primary side of the separation membrane module or the separation membrane of the ultrafiltration membrane module; and an air mixing unit is mixed with the membrane filtration water in the membrane filtration water return unit. . The water generating device of claim 9 or 10, wherein the air mixing unit is a water aspirator.