JP2001259376A - Deionized water making apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a deionized water making apparatus achieving the suppression of a rise in the difference pressure due to the passing of water through a reverse osmosis membrane apparatus (RO) or an electric deionized water making apparatus (EDI) during long-term operation by the drastic improvement of the EDI from a structural aspect without using a chemical agent. SOLUTION: The RO and the EDI are connected in series in this order and a desalting chamber is constituted by respectively filling two small desalting chambers, each of which is demarcated by a cation exchange membrane on one side, an anion exchange membrane on the other side and a central intermediate ion exchange membrane, with an anion exchanger and a mixed ion exchanger and concentration chambers are provided on both sides of the desalting chamber through the cation exchange membrane and the anion exchange membrane and the desalting chamber and the concentration chambers are arranged between an anode and a cathode to form the EDI and water to be (treated is allowed to flow in one small desalting chamber filled with the anion exchanger while voltage is applied and, subsequently, the outflow water of the small desalting chamber is allowed to flow in the other small desalting chamber and concentrated water is allowed to flow in the concentration chambers. By this constitution, deionized water containing no microorganisms is obtained from the desalting chamber and the membrane surfaces of the RO and the concentration chambers of the EDI can be suppressed from the generation of slime to the utmost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the field of semiconductor manufacturing,
Used in various industries or research laboratories such as medical and pharmaceutical manufacturing, power generation such as nuclear power and thermal power, food industry, etc., the differential pressure rise due to long-term water flow in reverse osmosis membrane devices and electric deionized water manufacturing devices The present invention relates to a deionized water production apparatus using an electric deionized water production apparatus capable of suppressing the occurrence of water.

[0002]

2. Description of the Related Art As a method for producing deionized water, there has been conventionally known a method in which deionized water is passed through ion-exchange resin through water to be treated. In order to eliminate such disadvantages in the treatment operation, it is necessary to regenerate with a chemical, and in recent years, a method for producing deionized water by an electric deionization method that does not require regeneration with a chemical has been established and put into practical use. Has been reached.

FIG. 5 is a schematic sectional view of a typical conventional electric deionized water producing apparatus. As shown in FIG. 5, the cation exchange membranes 101 and the anion exchange membranes 102 are alternately arranged at a distance from each other, and the ion exchange bodies 103 are alternately placed in a space formed by the cation exchange membranes 101 and the anion exchange membranes 102. Fill to form a desalination chamber. The anion exchange resin 103a is filled on the inflow side (front stage) of the water to be treated in the desalination chamber,
A mixed ion exchange resin 103b of a cation exchange resin and an anion exchange resin is filled on the outflow side (the latter stage) of the water to be treated in the desalination chamber. In addition, the portions not adjacent to the ion-exchanger 103 formed by the anion exchange membrane 102 and the cation exchange membrane 101 located next to the desalination chamber 104 are used as the concentration chamber 105 for flowing the concentrated water.

A cathode 109 is provided on one side of the desalting chamber, and an anode 110 is provided on the other end. The enrichment chamber 105 is located between the above-described spacers, and a partition such as a cation exchange membrane 101, an anion exchange membrane 102, or a simple non-ion exchange membrane is provided on both outer sides of the enrichment chamber 105 at both ends. The membrane is provided, and the portions where the two electrodes 109 and 110 are separated by the partition membrane are referred to as a cathode chamber 112 and an anode chamber 113, respectively. Thus, in the conventional electric deionized water producing apparatus, the number of the concentrating chambers is one more than the number of the desalting chambers,
Alternatively, when the concentrating chambers at both ends were used as electrode chambers without a partition membrane, the configuration was one less.

A case of producing deionized water by such an electric deionized water producing apparatus will be described with reference to FIG. That is, a direct current is passed between the cathode 109 and the anode 110, the water to be treated flows in from the water inflow line 111, the concentrated water flows in from the concentrated water inflow line 115, and the electrode water inflow lines 117, 117 From each of the electrode water flows. The water to be treated flowing from the treated water inflow line 111 flows down the desalting chamber 104, and firstly, when passing through the anion exchange resin 103a at the preceding stage, anion components such as hydrochloric acid ions and sulfate ions are removed. Upon passing through the mixed ion exchange resin 103b of the latter cation exchange resin and anion exchange resin, cation components such as magnesium and calcium are removed. The concentrated water flowing from the concentrated water inflow line 115 rises in each concentration chamber 105, receives impurity ions moving through the cation exchange membrane 101 and the anion exchange membrane 102, and forms concentrated water as concentrated water in which the impurity ions are concentrated. Electrode water flowing out of the outflow line 116 and further flowing in through the electrode water inflow lines 117 and 117 flows out of the electrode water outflow lines 118 and 118. Therefore, deionized water is obtained from the deionized water outflow line 114.

[0006]

Conventionally, a deionized water producing apparatus combining a reverse osmosis membrane apparatus and the above-mentioned electric deionized water producing apparatus has been used in the fields of semiconductor production, medicine and pharmaceutical production, nuclear power and thermal power. It has been used as a non-chemical deionized water production device in various industries such as the power generation field and the food industry. However, even in such a deionized water producing apparatus, in a long-term operation, the reverse pressure of the reverse osmosis membrane apparatus causes an increase in the differential water pressure, whereas the electric deionized water apparatus increases the differential pressure of the condensing chamber. Occurred, causing chemical cleaning.

[0007] The rise of the pressure difference in water flow in the reverse osmosis membrane device is as follows.
If left untreated, the amount of permeated water will decrease. It is possible to secure the amount of permeated water by increasing the operating pressure by controlling the valve operation and the pump inverter without performing chemical cleaning to a certain extent, but eventually reverse osmosis if the rise in the differential pressure of water flow is left unchecked This can cause damage to the membrane, leading to serious trouble. On the other hand, in the electric deionized water production system, the pressure difference in water flow in the concentrating chamber can be increased to some extent without chemical washing, and the operating pressure can be increased by operating the valve to secure the amount of concentrated water. If the rise is left unchecked, the flow rate distribution of the concentrated water will become non-uniform, causing precipitation of poorly soluble substances, generation of microorganisms, etc., and further increase in pressure. Also, the pressure balance between the desalting chamber and the concentrating chamber is lost, so that the concentrated water leaks to the desalting chamber through the ion exchange membrane,
It can also cause fluctuations in treated water quality. In order to prevent such troubles in advance, it is customary to wash the reverse osmosis membrane device and the electric deionized water production device with chemicals periodically or when the differential pressure rise exceeds a certain limit. In addition, stopping the apparatus due to chemical cleaning is inconvenient in terms of operation management and cost.

In a conventional electric deionized water producing apparatus, a deionization chamber filled with a mixed ion exchange resin of an anion exchange resin and a cation exchange resin is used in the deionization chamber.
H is in the vicinity of 7, and filamentous fungi and mold spores and the like in the inflowing treated water grow in the desalting chamber, increasing the pressure difference in the desalting chamber, lowering the water quality, and contaminating microorganisms in the treated water. There was a problem. In addition, the upstream side of the desalting chamber is filled with an anion exchange resin, and the downstream side is filled with a mixed ion exchange resin of an anion exchange resin and a cation exchange resin. However, the problem of the increase in the differential pressure of water in the reverse osmosis membrane device and the electric deionized water production device in the long-term operation as described above has not been solved.

[0009] Accordingly, an object of the present invention is to suppress the rise in the differential pressure due to the passage of water in a reverse osmosis membrane device or an electric deionized water production apparatus during a long-term operation without using a chemical. It is an object of the present invention to provide a deionized water production apparatus which can be achieved by a fundamental improvement in the structure of a production apparatus and further suppresses the incorporation of microorganisms into deionized water.

[0010]

Under such circumstances, the present inventors have conducted intensive studies. As a result, (1) the differential pressure of water flow generated in the enrichment chamber of the conventional electric deionized water producing apparatus is as follows:
(2) The slime adhering on the cation exchange membrane surface on the cation exchange membrane surface on the side of the concentration chamber is a microorganism which is unrelated to the hardness component of the water to be treated. It is caused by metabolites and fine particles in water. Even if sufficient measures are taken to remove hardness components such as softening in the front part of the electric deionized water production equipment, the surface of the cation exchange membrane can be That occur on,
(3) When the concentrated water of the apparatus is returned to the previous stage of the reverse osmosis membrane apparatus, slime adheres to the membrane surface of the reverse osmosis membrane apparatus, and this causes a difference in water flow through the reverse osmosis membrane apparatus. This phenomenon is caused by microorganisms and slime grown in the concentration chamber of the electrodeionized water production system. (4) A cation exchange membrane is sealed on one side of the frame and an anion exchange membrane is sealed on the other side. In the conventional structure of the conventional desalination chamber, an intermediate ion exchange membrane that divides the desalination chamber into two parts is further disposed between the cation exchange membrane and the anion exchange membrane, and two small desalination chambers are provided adjacent to each other. An anion exchanger is placed in the small desalination chamber on the anode side where the water to be treated first flows, and an anion exchanger is placed in the small desalination chamber on the cathode side where the effluent of the small desalination chamber flows. And a mixed exchanger of a cation exchanger and the cation exchange membrane, anion exchange The above-mentioned (1) can be achieved by using an electric deionized water producing apparatus having a structure in which concentration chambers are provided on both sides of a desalination chamber via a membrane, and the desalination chamber and the concentration chamber are arranged between an anode and a cathode. The phenomena of (3) are all improved,
Furthermore, the inventors have found that deionized water obtained from the desalting chamber can be of a stable water quality free of microorganisms, and have completed the present invention.

That is, the present invention (1) relates to a deionized water producing apparatus in which a reverse osmosis membrane apparatus and an electric deionized water producing apparatus are connected in this order. Small desalination chamber on the cathode side of two small desalination chambers partitioned by a cation exchange membrane on the side, an anion exchange membrane on the other side, and an intermediate ion exchange membrane located between the cation exchange membrane and the anion exchange membrane A deionization chamber is formed by filling a mixed ion exchanger of a cation exchanger and an anion exchanger, and filling an anion exchanger in a small desalination chamber on the anode side, respectively, through the cation exchange membrane and the anion exchange membrane. The present invention provides a deionized water production apparatus formed by providing concentration chambers on both sides of a deionization chamber and arranging the deionization chamber and the concentration chamber between an anode and a cathode. With this configuration, when a part of the water to be treated is supplied to the concentration chamber, the microorganisms that are usually negatively charged are applied with a direct current and move to the anode side. On the anode side of the concentration chamber, there is a cation exchange membrane that separates the concentration chamber and the desalination chamber, and microorganisms are captured on the cation exchange membrane surface. On the other hand, a small desalination chamber (cathode side) partitioned by a cation exchange membrane and an intermediate ion exchange membrane on one side is filled with a mixed ion exchanger of a cation exchanger and an anion exchanger,
Since cations such as sodium ions move from the entire surface of the cation exchange membrane to the concentration chamber, the concentrated water in the vicinity of the entire surface of the cation exchange membrane becomes rich in sodium ions and becomes an alkaline state, so that microorganisms are unlikely to grow. Therefore, no sticky slime caused by microorganisms is generated on the cation exchange membrane surface, and the pressure difference in water flow in the concentration chamber can be kept constant for a long period of time. In addition, on the inlet side of the small desalination chamber into which the water to be treated first flows, accumulation of fine turbid substances present in the treated water is inevitable, and filamentous fungi and mold spores are present in the turbid substance. In this case, the small desalting chamber is filled with an anion exchanger, and the anion is selectively removed to be alkaline. Therefore, water free of microorganisms can be supplied to the small inflow desalting chamber that flows in, and as a result, water substantially free of microorganisms can be obtained from the electric deionized water producing apparatus.

Further, the present invention (2) further comprises a pipe for returning the concentrated water flowing out of the concentration chamber to the water to be treated side of the reverse osmosis membrane device, wherein the deionized water producing apparatus according to the above (1) is provided. Is provided. By adopting such a configuration, the concentrated water returned to the water to be treated side of the reverse osmosis membrane device is difficult for microorganisms to proliferate, and therefore has no influence on the membrane surface of the reverse osmosis membrane device, and is thus different from the conventional one. In contrast, a pressure difference is much less likely to occur.

Further, the present invention (3) provides a reverse osmosis membrane device, wherein the reverse osmosis membrane device includes a first stage reverse osmosis membrane device and a second stage reverse osmosis membrane device for further treating permeated water of the first stage reverse osmosis membrane device. And (1) comprising a pipe for returning the concentrated water flowing out of the concentration chamber from the permeated water side of the first-stage reverse osmosis membrane device to the treated water side of the second-stage reverse osmosis membrane device. It is intended to provide a deionized water producing apparatus as described above. By adopting such a configuration, in addition to achieving the same effects as the above-described invention, it is possible to improve the water utilization rate, and to return the concentrated water to the permeated water side of the first-stage reverse osmosis membrane device. The processing amount of the one-stage reverse osmosis membrane device is reduced, and the device becomes a reasonable device.

Further, the present invention (4) further comprises a pipe for returning the concentrated water of the second-stage reverse osmosis membrane device to the treated water side of the first-stage reverse osmosis membrane device. To provide a deionized water producing apparatus. By adopting such a configuration, the same effects as those of the above-described invention can be obtained, and the water utilization rate can be further improved.

Further, the present invention (5) provides the apparatus for producing deionized water according to the above (1), wherein the reverse osmosis membrane used in the reverse osmosis membrane device is a polyamide membrane. By adopting such a configuration, the operation pressure is conventionally high (1.5 to 3.0 MPa) and the separation performance is inferior, but it can be sterilized with a disinfectant such as sodium hypochlorite, and the charge on the membrane surface is neutral. Cellulose acetate-based membranes, which are difficult to contaminate because of their low contamination, were considered advantageous in terms of slime generation countermeasures.However, since the generation of slime can be minimized, sodium hypochlorite etc. Can not be sterilized with the disinfectant of
The separation performance is liable to decrease when subjected to oxidative deterioration, and the membrane surface is easily contaminated due to the charge and hydrophobicity of the membrane surface, but the operating pressure is low (0.3 to 1.5 MPa) and the separation performance is low. High polyamide-based membranes can be used, and when using the membranes, there is more choice.

In the present invention (6), the apparatus for producing deionized water according to (1), further comprising an ultraviolet oxidizer or an ultraviolet sterilizer before the reverse osmosis membrane apparatus or the electric deionized water producing apparatus. Is provided. By adopting such a configuration, in addition to achieving the same effects as the above-described invention, the microorganisms in the water to be treated are sterilized in advance, or the nutrient sources of the microorganisms are cut off by oxidation of organic substances, so that the growth of microorganisms is further suppressed. .

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An electric deionized water producing apparatus used in the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram of an electric deionized water producing apparatus according to the present embodiment. As shown in FIG. 1, the cation exchange membrane 3, the intermediate ion exchange membrane 5, and the anion exchange membrane 4 are alternately arranged while being separated from each other, and ion exchange is performed in a space formed by the cation exchange membrane 3 and the intermediate ion exchange membrane 5. The body 8 is filled to form first small desalination chambers d ₁ , d ₃ , d ₅ , d ₇ , and the intermediate ion exchange membrane 5
And by filling the ion exchanger 8 in the space formed by the anion exchange membrane 4 to form a second small depletion chambers _{d 2, d 4, d 6} , d 8, a first small depletion chamber d ₁ Desalting room D in second small desalting room d _2
1, the first small depletion chambers d ₃ and the second small depletion chamber d ₄ desalting compartment D _2, desalting compartment between the first small depletion chamber d ₅ second small depletion chambers d ₆ D
_3, desalting compartment between the first small depletion chamber d ₇ second small depletion chambers d ₈ D ₄
And In addition, the portion not filled with the ion exchanger 8 formed by the anion exchange membrane 4 and the cation exchange membrane 3 located next to the desalting chambers D ₂ and D ₃ respectively has the enrichment chamber 1 for flowing the concentrated water. I do. These are sequentially provided side by side to form a desalting room D ₁ , a concentration room 1, a desalination room D ₂ , a concentration room 1, a desalination room D ₃ , a concentration room 1, and a desalination room D ₄ from the left in the figure. . Further, in two small desalination chambers adjacent to each other via the intermediate film, the treated water outflow line 12 of the second small desalination chamber is connected to the treated water inflow line 13 of the first desalination chamber. Here, the ion exchanger packed in the first small desalting chambers d ₁ , d ₃ , d ₅ and d ₇ is a mixed ion exchanger of an anion exchanger and a cation exchanger, and the second small desalting chamber d _2, d _4, the ion exchange material packed in d _6, d ₈ is an anion exchanger. The enrichment room 1
Can also be filled with ion exchangers as spacers or to reduce the electrical resistance of the concentration chamber.

Such a desalting chamber is composed of a deionized module formed by two internally hollowed frames and three ion exchange membranes. That is, although not shown in the figure, a cation exchange membrane is sealed on one side of the first frame, and a hollow portion of the first frame is filled with a mixed exchanger of a cation exchanger and an anion exchanger, and then Then, an intermediate ion exchange membrane is sealed to the other part of the first frame to form a first small desalting chamber. Next, the second frame is sealed so as to sandwich the intermediate ion exchange membrane, the hollowed portion of the second frame is filled with an anion exchanger, and then the other portion of the second frame is anion exchange membrane. To form a second small desalination chamber. The ion exchange membrane is relatively soft, and when the inside of the first frame and the second frame is filled with the ion exchanger and both surfaces thereof are sealed with the ion exchange membrane, the ion exchange membrane is curved. In order to prevent the packed bed of the ion exchanger from becoming non-uniform, the first frame,
A plurality of ribs are provided vertically in the space of the second frame. Also, the first
An inlet for treated water or an outlet for treated water is provided above the frame and the second frame, and an outlet for treated water and an inlet for treated water are provided below the frame. FIG. 1 shows a state in which a plurality of such deionization modules are juxtaposed with a spacer (not shown) interposed therebetween, and a cathode 6 is arranged on one side of the juxtaposed deionization modules. And the anode 7 is disposed on the other end. The position sandwiching the above-mentioned spacer is the concentration chamber 1, and a partition membrane such as a cation exchange membrane, an anion exchange membrane, or a simple membrane having no ion exchange property is provided on both outer sides of the desalting chamber D at both ends as necessary. Are disposed, and the two electrodes 6 separated by the partition film,
The portions contacting with each other may be the electrode chambers 2 and 2, respectively.

According to such an electric deionized water producing apparatus,
When producing deionized water by
You. That is, a direct current is passed between the cathode 6 and the anode 7,
When treated water flows in from the treated water inflow line 11
The concentrated water flows from the concentrated water inflow line 15
Electrode water flows from the polar water inflow lines 17 and 17, respectively.
You. The treated water flowing from the treated water inflow line 11
2 small desalination room d_Two, D_Four, D₆, D₈Down the anion
Anion components are removed when passing through the packed bed of exchanger 81
Is done. Further, the treated water outflow line 12 of the second small desalination chamber is
The effluent that has passed is the treated water inflow line 1 in the first small desalination chamber.
3 through the first small desalination chamber d₁, D_Three, D _Five, D₇Flow down
Here, too, a mixture of an anion exchanger and a cation exchanger is used.
When passing through the packed bed of the on-exchanger 82, cations and
Nion impurity ions are removed and deionized water is deionized
From the water outflow line 14. The concentrated water inflow
The concentrated water flowing from the in 15 rises in each of the concentration chambers 1 and
Moving through the thione exchange membrane 3 and the anion exchange membrane 4
Incoming impurity ions and concentrates the impurity ions.
The condensate is discharged from the concentrated water discharge line 16 as compressed water,
Electrode water flowing from the electrode water inflow lines 17 and 17
The water flows out of the water outflow lines 18, 18. The above operation
Therefore, impurity ions in the water to be treated are electrically removed.
You. In addition, the thickness of the first small desalination chamber and the second small desalination chamber is particularly
Although not limited, the thickness of the first small desalination chamber is 0.8 to 8 mm,
Preferably 2 to 5 mm, thickness of the second small desalination chamber 5 to 15 m
m, preferably 6-10mm, lower electrical resistance
And higher current efficiency and better water quality
This is preferred in that

Further, in the above-mentioned water passing method, the concentration chamber 1
Microorganisms present in concentrated water flowing through
Therefore, a direct current is applied to move to the anode 7 side. Dark
On the anode side of the contraction chamber 1, the concentration chamber 1 and the first small desalination chamber d₁,
d_Three, D_Five, D₇Cation exchange membrane 3 that separates
Then, microorganisms are captured on the surface of the cation exchange membrane 3.
On the other hand, one side of the cation exchange membrane 3 and the intermediate ion exchange membrane 5
1st small desalination chamber d ₁, D_Three, D_Five, D₇Mosquito
Mixed ion exchanger 82 of thione exchanger and anion exchanger
Is filled from the entire surface of the cation exchange membrane 3.
When cations such as thorium ions move to the concentration chamber 1
Therefore, the concentrated water near the entire surface of the cation exchange membrane 3 is sodium.
It becomes ion-rich and becomes alkaline, and microorganisms grow.
hard. For this reason, the surface of the cation exchange membrane
No sticky slime is generated, and
Water pressure difference can be maintained for a long time
You. The second small desalination chamber into which the water to be treated flows first
d_Two, D_Four, D₆, D₈Is located in the water to be treated
Accumulation of fine turbid matter is inevitable,
If bacteria or mold spores are present, the second small desalination chamber d
_Two, D_Four, D₆, D₈Is filled with an anion exchanger
The anion is selectively removed to make it alkaline,
The growth of organisms is suppressed. Therefore, the next
One desalting room d₁, D_Three, D_Five, D₇Microorganisms
Water can be supplied, resulting in an electric deionized water production system.
The treated water flowing out of the storage is also substantially free of microorganisms.
Is obtained. For the intermediate ion exchange membrane, click
In the case of an on-exchange membrane, cations are transferred from the second small desalting chamber to the first small
Moved to the desalination chamber and the sterilization effect in the second small desalination chamber is weak.
Therefore, it is preferable to use an anion exchange membrane.
No.

As described above, the concentrated water in the vicinity of the entire surface of the cation exchange membrane 3 becomes rich in sodium ions and becomes alkaline, so that microorganisms are unlikely to grow. On the other hand, no microorganisms are present in the treated water finally obtained from the desalting chamber. Water is obtained because of the unique structure of the desalination chamber as shown in FIG. This is compared with a conventional desalination chamber structure. That is, the electric deionized water production apparatus 100 of FIG. 5 which is an example of the conventional example has an anion exchanger 103a on the upstream side of the desalination chamber.
A mixed ion exchanger 103b of an anion exchanger and a cation exchanger is filled on the downstream side of the desalting chamber. In this case, since the water to be treated is first subjected to anion exchange, the pH shifts to the alkaline side, and the growth of microorganisms can be prevented, which is advantageous. However, in the concentrated water near the cation exchange membrane 101 on the upstream side of the concentration chamber, since the inflow of cations from the desalting chamber is relatively small, the concentrated water hardly becomes alkaline, and thus the growth of microorganisms cannot be suppressed. Another conventional example is one in which a desalination chamber is filled with a mixed ion exchanger of an anion exchanger and a cation exchanger. In this case, both the anion exchange and the cation exchange are performed in the desalting chamber, which is neutral, and it is inevitable that microorganisms enter the desalted water.

The flow direction of the water to be treated in the first small-scale desalination chamber and the second small-scale desalination chamber is not particularly limited. The flow direction in the small desalination chamber may be different. The small desalination chamber into which the water to be treated flows is, in addition to the above-described embodiment, first, the water to be treated flows into the first desalination chamber, and then flows down. You may make it flow into a 2nd desalination chamber. Also, the flow direction of the concentrated water is appropriately determined.

Next, an apparatus for producing deionized water according to an embodiment of the present invention will be described with reference to FIGS. FIG.
FIG. 2 is a block diagram showing a deionized water producing apparatus according to the first embodiment. A deionized water producing apparatus 20a includes a decarbonation tower 22, a reverse osmosis membrane device 21, and an electric deionized water producing device 10 in this order. They are connected in series by pipes 30b and 30c. The electric deionized water producing apparatus 10 has the structure shown in FIG. 1, a pipe 33 branched from a pipe 30 c is an inflow pipe of a concentration chamber, a pipe 34 a is a return pipe of a concentrated water, and an outflow pipe 35 of the concentration chamber. Treated water inflow pipe 30a
Is linked to Further, the pipe 31 is connected to the second small desalination chamber d ₂ ,
d _4, d _6, is d ₈ inlet pipe (symbol 11 in FIG. 1), deionized water outlet pipe 30d is first small depletion chambers d _1, d
_3, is a d _5, d ₇ outlet pipe 30d. 211 is a reverse osmosis membrane.

The decarbonation tower 22 is installed to remove dissolved gas components such as carbonic acid in raw water, especially carbonic acid.
A known decarbonation tower can be used. In addition, you may use a membrane decarbonation apparatus instead of a decarbonation tower. The reverse osmosis membrane device 21 is installed in order to reduce the load on the electric deionized water production device 10 in the subsequent stage, and a known reverse osmosis membrane device (reverse osmosis membrane module) can be used. The reverse osmosis membrane used for the reverse osmosis membrane device 21 is not particularly limited, and examples thereof include a cellulose acetate-based asymmetric membrane and a polyamide-based composite synthetic membrane. The cellulose acetate asymmetric membrane has a high operating pressure (1.5 to 3.0 MPa) and poor separation performance, but can be sterilized with a disinfectant such as sodium hypochlorite, and has a neutral charge on the membrane surface. This is advantageous in that it is difficult to stain. In addition, the polyamide-based composite synthetic membrane cannot be sterilized with a disinfectant such as sodium hypochlorite, and when subjected to oxidative deterioration, the separation performance tends to decrease, and the membrane surface is easily stained due to the charge and hydrophobicity of the membrane surface. Despite the disadvantages, the operating pressure is low (0.3 ~
1.5 MPa), which is advantageous in that the separation performance is high. In the reverse osmosis membrane device 21 of the present invention, since the generation of slime can be suppressed as much as possible, it can be used even with a polyamide-based composite synthetic membrane. Examples of the form of the reverse osmosis membrane device include a spiral module, a hollow fiber module, and a flat membrane module.

The electric deionized water producing apparatus 10 is for making the quality of the permeated water of the reverse osmosis membrane apparatus 21 higher deionized water. The structure, deionizing action and slime generation suppressing action are as described above. It is. In addition, the concentrated water of the electric deionized water producing apparatus 10 is returned to the water to be treated side of the decarbonation tower to increase the water utilization rate.

FIG. 3 is a block diagram showing a deionized water producing apparatus according to the second embodiment. In FIG. 3, the same components as those in FIG. Only the points will be described. That is, FIG.
2 is different from FIG. 2 in that a membrane decarbonation device 24 is used instead of the decarbonation tower 22, and further upstream of the connection point A of the concentrated water return pipe 34 a before the membrane decarbonation device 24. A reverse osmosis membrane device 21a is provided, and the reverse osmosis membrane device 21a and the membrane decarbonation device 24 are connected by a pipe 30e. Further, the concentrated water side of the reverse osmosis membrane device 21 and the inflow of treated water of the reverse osmosis membrane device 21a The point is that it is connected to the pipe 30a. In the following description, 21a is referred to as a first-stage reverse osmosis membrane device, and 21 is referred to as a second-stage reverse osmosis membrane device.

The membrane decarbonation device 24 is installed to remove dissolved gas components such as carbon dioxide in raw water, particularly, carbon dioxide, and a known membrane decarbonation device can be used. Further, the degassing membrane used in the membrane decarbonation device 24 is a porous membrane made of a hydrophobic material, and has a property of transmitting gas but not liquid. Examples of the material of the degassing film include a porous film made of polypropylene, polyethylene, silicone resin, fluororesin, or the like. In this case, a decarbonation tower can be used instead of the membrane decarbonation device,
In order to maintain the quality of the treated water, a membrane decarbonation device is preferable. That is, since the membrane decarbonation device degass by depressurizing the opposite side of the membrane through which the water to be treated flows, the water to be treated is hardly contaminated in the device, which is convenient for degassing the permeated water of the reverse osmosis membrane. is there. On the other hand, the decarbonation tower blows air into the water to be treated,
Contaminants in the air may migrate to the water to be treated,
It is not advisable to use it for the permeated water of a reverse osmosis membrane.

According to the deionized water producing apparatus 20b of the second embodiment, the same effect as that of the deionized water producing apparatus 20a of the first embodiment can be obtained, and the water utilization rate can be improved. In order to return the concentrated water flowing out of the concentration chamber of the electric deionized water production apparatus 10 to the permeated water side of the first-stage reverse osmosis membrane apparatus, the throughput of the first-stage reverse osmosis membrane apparatus Is reduced and the device becomes reasonable.

FIG. 4 is a block diagram showing a deionized water producing apparatus according to a third embodiment. In FIG. 4, the same components as those in FIG. Only the points will be described. That is, FIG.
2 is different from FIG. 2 in that an ultraviolet sterilizer 23 is installed between the reverse osmosis membrane device 21 and the electric deionized water producing device 10, and the reverse osmosis membrane device 21 and the ultraviolet sterilizer 23 are connected to the piping 3.
0f, and the ultraviolet sterilizer 23 and the electric deionized water producing apparatus 10 are connected by a pipe 30g.
The ultraviolet sterilizer may be any device that has an ultraviolet lamp capable of irradiating a wavelength around 254 nm and can sterilize the water to be treated.

According to the deionized water producing apparatus 20c of the third embodiment, the same effects as those of the deionized water producing apparatus 20a of the first embodiment can be obtained, and the electric deionized water producing apparatus can be produced. Since almost no microorganisms or the like are present in the influent water of the apparatus 10, almost no sticky slime caused by the microorganisms is generated on the cation exchange membrane surface, and the pressure difference in water flow in the concentrating chamber 1 becomes longer. A constant state can be maintained. Also, sticky slime caused by microorganisms hardly occurs on the membrane surface of the reverse osmosis membrane device 21, and similarly, the pressure difference in water flow in the reverse osmosis membrane device 21 remains constant for a long period of time. Can be kept.

In the deionized water producing apparatus 20c according to the third embodiment, an ultraviolet oxidizing apparatus may be used instead of or together with the ultraviolet sterilizing apparatus 23. By using an ultraviolet oxidation device, nutrient sources of microorganisms are cut off by oxidation of organic matter in the water to be treated, and thus the growth of microorganisms is further suppressed. The ultraviolet oxidation device may be any device that has an ultraviolet lamp capable of irradiating at least a wavelength around 185 nm to the water to be treated and can decompose organic substances in the water to be treated. An ultraviolet oxidation apparatus is an apparatus capable of irradiating ultraviolet rays having a wavelength of about 254 nm, which has a lower ability to decompose organic substances, in addition to ultraviolet rays having a wavelength of about 185 nm.

In the deionized water producing apparatus 20c according to the third embodiment, another reverse osmosis membrane apparatus may be installed in front of the decarbonation tower 22 of the deionized water producing apparatus 20c. In this case, as in the second embodiment, the second
The concentrated water of the reverse osmosis membrane device may be returned to the treated water side of the first reverse osmosis membrane device. Thereby, the utilization rate of water can be improved. Further, the concentrated water return pipe 34a flowing out of the concentrated chamber may be omitted, and the concentrated water may be blown out of the system. Further, a concentrated water return pipe flowing out of the concentrating chamber may be connected to the pipe 33 to adopt a concentrated water circulation mode. Further, in the concentrated water circulation mode, an ultraviolet sterilizer or an ultraviolet oxidizer may be further installed in the concentrated water circulation system. Further, the installation position of the ultraviolet sterilizer 23 may be replaced with the position shown in FIG. 4, that is, on the upstream side of the reverse osmosis membrane device 21, that is, in the middle of the pipe 30 a or the middle of the pipe 30 b.

In the present invention, the water to be treated is not particularly limited and includes, for example, well water, tap water, sewage, industrial water,
Examples include river water, washing wastewater for semiconductor devices in a semiconductor manufacturing plant, or recovered water from a concentration chamber, and these can be used alone or in a mixed state.

[0034]

According to the present invention (1), when a part of the water to be treated is supplied to the concentration chamber, the microorganisms which are usually negatively charged are moved to the anode side by applying a direct current, and the cation exchange is performed. Captured on the membrane surface. On the other hand, the concentrated water in the vicinity of the entire surface of the cation exchange membrane is rich in sodium ions and becomes in an alkaline state, and it is difficult for microorganisms to grow. Therefore, no sticky slime caused by microorganisms is generated on the cation exchange membrane surface, and the pressure difference in water flow in the concentration chamber can be kept constant for a long period of time. In addition, on the inlet side of the small desalination chamber into which the water to be treated first flows, accumulation of fine turbid substances present in the treated water is inevitable, and filamentous fungi and mold spores are present in the turbid substance. In this case, the small desalting chamber is filled with an anion exchanger, and the anion is selectively removed to be alkaline. Therefore, water free of microorganisms can be supplied to the next small desalination chamber, and as a result, water substantially free of microorganisms can be obtained from the electric deionized water production device.

According to the present invention (2), the concentrated water returned to the water to be treated of the reverse osmosis membrane device is such that microorganisms are unlikely to proliferate, and therefore the influence on the membrane surface of the reverse osmosis membrane device is reduced. Therefore, the water pressure difference is much less likely to occur than the conventional one. Further, according to the present invention (3), the utilization rate of water can be improved, and the concentrated water is returned to the permeated water side of the first-stage reverse osmosis membrane device. The amount of processing is reduced, and the device becomes a reasonable device. Further, according to the present invention (4), the water utilization rate can be further improved. Also,
According to the present invention (5), in addition to the cellulose acetate-based membrane, which has conventionally been considered advantageous in terms of slime generation countermeasures,
A polyamide-based membrane having a low operating pressure (0.3 to 1.5 MPa) and a high separation performance can be used, so that there is a wider range of choices when using the membrane. Further, according to the present invention (6), the microorganisms in the water to be treated are sterilized in advance or the nutrient sources of the microorganisms are cut off by the oxidation of organic substances, so that the growth of the microorganisms is further suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one example of an electric deionized water producing apparatus used in the present invention.

FIG. 2 is a block diagram of a deionized water producing apparatus according to the embodiment of the present invention.

FIG. 3 is a block diagram of a deionized water producing apparatus according to another embodiment of the present invention.

FIG. 4 is a block diagram of a deionized water producing apparatus according to another embodiment of the present invention.

FIG. 5 is a schematic view of a conventional electric deionized water producing apparatus.

[Explanation of symbols]

D, D _{1 to} D ₄ , 104 Desalination chamber d ₁ , d ₃ , d ₅ , d ₇ First small desalination chamber d ₂ , d ₄ , d ₆ , d ₈ Second small desalination chamber ₁ , 105 Concentration Chamber 2, 112, 113 Electrode chamber 3, 101 Cation membrane 4, 102 Anion membrane 5 Intermediate ion exchange membrane 6, 109 Cathode 7, 110 Anode 8, 103 Ion exchanger 10, 100 Electric deionized water producing apparatus 11, 31 , 111 treated water inflow line 12 treated water outflow line in second small desalination chamber 13 treated water inflow line in first small desalination chamber 14, 30d, 114 deionized water outflow line 15, 33, 115 concentrated water inflow Line 16, 116 Concentrated water outflow line 17, 117 Electrode water inflow line 18, 118 Electrode water outflow line 20a to 20c Deionized water production device 21, 21a Reverse osmosis membrane device 22 Decarbonation tower 23 Ultraviolet sterilizer 24 Membrane Carbonate apparatus 30a~30g pipe 34a~34b mixed ion exchangers concentrated water return pipe 81 anion exchanger 82 anion and a cation

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C02F 1/469 C02F 1/46 103 F term (Reference) 4D006 GA03 GA17 HA01 HA41 HA47 HA61 JA30A JA42A JA43A JA44A KA02 KA51 KB04 KB17 MA03 MA13 MA14 MC54 PB04 PB05 PB06 PB07 PB08 PC01 PC02 PC11 PC31 PC32 PC33 PC42 4D037 AA03 AA11 AB03 BA18 BA23 CA03 CA11 4D061 DA03 DA08 DB13 EA09 EB13 ED17 FA03 FA07 FA09 FA16

Claims (6)

[Claims] 1. A deionized water producing apparatus in which a reverse osmosis membrane device and an electric deionized water producing device are connected in this order, wherein the electric deionized water producing device comprises a cation exchange membrane on one side, Of the two small desalination chambers partitioned by the anion exchange membrane on the negative side and the intermediate ion exchange membrane located between the cation exchange membrane and the anion exchange membrane, the cation exchanger and anion The mixed ion exchanger of the exchanger is filled with an anion exchanger in the small desalting chamber on the anode side to form a desalting chamber, and the cation exchange membrane and the anion exchange membrane are provided on both sides of the desalination chamber via the anion exchange membrane. An apparatus for producing deionized water, comprising: a concentration chamber; and a desalination chamber and a concentration chamber arranged between an anode and a cathode. 2. The deionized water producing apparatus according to claim 1, further comprising a pipe for returning the concentrated water flowing out of the concentration chamber to the treated water side of the reverse osmosis membrane device. 3. The reverse osmosis membrane device comprises a first-stage reverse osmosis membrane device and a second-stage reverse osmosis membrane device for further processing permeated water of the first-stage reverse osmosis membrane device, and the concentration chamber. A pipe for returning the concentrated water flowing out from the permeated water side of the first-stage reverse osmosis membrane device to the treated water side of the second-stage reverse osmosis membrane device. Ion water production equipment. 4. The deionization system according to claim 3, further comprising a pipe for returning the concentrated water of the second-stage reverse osmosis membrane device to the water to be treated of the first-stage reverse osmosis membrane device. Water production equipment. 5. The deionized water production apparatus according to claim 1, wherein the reverse osmosis membrane used in the reverse osmosis membrane device is a polyamide-based membrane. 6. The apparatus for producing deionized water according to claim 1, further comprising an ultraviolet oxidizing apparatus or an ultraviolet sterilizing apparatus in front of the reverse osmosis membrane apparatus or the electric deionized water producing apparatus.