JP2001170630A - Pure water production device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrapure water production device in which a water utilization as a total system is enhanced, a production cost of finally produced ultrapure water is lowered, generation of slime, etc., in a concentrated water circulation system of an electric regeneration type desalting device is efficiently suppressed, and a reverse osmosis membrane device, etc., is efficiently operated. SOLUTION: This pure water production device is provided with the reverse osmosis membrane device for treating water to be treated, the electric regeneration type desalting device for treating transmitted water through the reverse osmosis membrane device, an UV ray irradiation device for treating the water treated by the electric regeneration type desalting device, and a cross-flow type membrane separation device for treating the water treated by the UV ray irradiation device. A concentrated water recovery line by which at least a portion of concentrated water by the cross flow type membrane separation device is returned to an inlet side of the electric regeneration type desalting device, is provided on the device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pure water producing apparatus, and more particularly to a pure water producing apparatus used in a semiconductor device producing process or the like.
The present invention relates to a pure water production apparatus suitable for producing ultra-pure water.

[0002]

2. Description of the Related Art Water to be treated as raw water of ultrapure water is, for example, well water, municipal water, industrial water, etc., or water that has been used at the place where ultrapure water is used and is relatively lightly contaminated. It is a collected wastewater which can be collected and reused after predetermined treatment of water or as it is.

[0003] A conventional ultrapure water production apparatus is configured in a system as shown in FIG. 6, for example. In FIG. 6, the above-mentioned water to be treated 101 is first subjected to a filtration treatment with a filtration device 102 (for example, a sand filtration device) to remove suspended impurities and the like. A pretreatment for removing carbon dioxide gas dissolved in the water to be treated in a state of being saturated or higher is performed by a decarbonation device 103 including a tower and a membrane deaerator. The treated water subjected to the pretreatment is subjected to treatment by the reverse osmosis membrane device 104 to remove particulate and ionic impurities. The non-permeated water in the reverse osmosis membrane device 104 is discharged as concentrated wastewater 105, and the permeated water is sent to the electric regeneration type desalination device 106 to remove most of the remaining ionic impurities in the water to be treated. . In the electric regeneration type desalination apparatus 106, an ion exchanger (for example, an ion exchange resin) is usually filled in a desalination chamber 107, and the water to be treated is passed through the desalination chamber 107. The concentrated water is circulated in the concentration chamber 108 separated by the ion exchange membrane, and the concentrated water circulation system is commonly used as a path of the electrode water circulated in the electrode chamber 109 formed in the electrode arrangement portion. There are many. The concentrated water circulation system 110 includes a circulation pump 111
And, optionally, a concentrated water tank 112,
From the concentrated water circulation system 110, the electric regeneration type desalination device 106
The concentrated water is appropriately partially discharged to adjust the concentration of by-product chlorine and ozone components in the electrode chamber. The electric regeneration type desalination device 106 is capable of continuous operation without substantially performing the regeneration treatment of the ion exchanger, as compared with the conventional regeneration type ion exchange resin device. Electric regeneration type desalination equipment 10
The treated water according to No. 6 is pure water having high purity and can be sufficiently used in ordinary applications.

However, for applications requiring higher purity pure water, so-called ultrapure water, such as a semiconductor device manufacturing process, a treatment for further increasing the purity is performed.
That is, the treated water from the electric regeneration type desalination device 106 is
For example, the treated water once stored in the pure water tank 113 and obtained from the primary pure water system up to this point is further subjected to the treatment with the secondary pure water system therefrom to produce ultrapure water.

In the secondary pure water system, for example, a treatment such as sterilization is performed by irradiating ultraviolet rays having a specific wavelength with an ultraviolet irradiator 114, or an organic substance in the water to be treated is oxidized to form carbonic acid and organic substances. Or be decomposed into For example, ions and the like in the water to be treated are finally removed by a disposable-type cartridge-type polisher 115 filled with an ion-exchange resin. Fine particles are finally removed by the device 116. As the cross flow type membrane separation device 116, an ultrafiltration membrane device, a microfilter device, a reverse osmosis membrane device, or the like can be used. The permeated water of the cross flow type membrane separation device 116 is supplied to a predetermined use place as ultrapure water, and the concentrated water in the cross flow type membrane separation device 116 is supplied to the reverse osmosis membrane device 104 via the concentrated water recovery line 117. The particles are returned to the inlet side, subjected to the above-described series of processing, and various particles concentrated and removed by the cross-flow type membrane separation device 116 in the concentrated water are discharged together with the wastewater 105 from the reverse osmosis membrane device 104. It has become so. In the secondary pure water system, if the operation is stopped, the quality of the treated water may not be stable due to the accumulation of impurities on the membrane surface or the growth of microorganisms on the membrane surface. In order to reduce the amount of water supplied to the place of use and to cope with fluctuations in the amount of water supplied to the place of use, the processing water of the cross-flow type membrane separation device 116 is always returned to the pure water tank 113 through the circulation line 118. ing.

[0006]

However, the following problems remain in the ultrapure water production apparatus using the conventional electric regeneration type desalination apparatus 106 as described above. First,
Concentrated water from the cross-flow type membrane separation device 116 is substantially entirely returned to the inlet side of the reverse osmosis membrane device 104, and a large amount of non-permeated water is discharged as wastewater 105 in the reverse osmosis membrane device 104. Since the concentrated water from the cross-flow type membrane separation device 116 is water that has been treated by the ultraviolet irradiation device 114,
A large amount of the water subjected to the treatment is discarded. Therefore, especially from the viewpoint of the ultraviolet irradiation device 114, the ratio of the treated water (ultra pure water) finally supplied to the place of use to the supplied treated water, that is, the water utilization rate is low. Since the ultraviolet irradiation device 114 consumes a relatively large amount of electric power for the irradiation of ultraviolet light of a predetermined wavelength, such a low water utilization rate has a great effect on the production cost of ultrapure water, and the ultraviolet light irradiation device 114 needs to be used at a place of use. The production cost per unit flow rate of the supplied ultrapure water is increased. Further, the reverse osmosis membrane device 104 usually contains a large number of reverse osmosis membrane elements, and untreated water is passed through each element.
When substantially all of the concentrated water from the osmosis is returned to the inlet side of the reverse osmosis membrane device 104, the water utilization rate also decreases in the reverse osmosis membrane device 104, and eventually, the number of reverse osmosis membrane elements must be increased, or Then, there arises a problem that the life of each element is shortened, and the production cost of ultrapure water also increases.

Further, in the concentrated water circulating system of the electric regeneration type desalination device 106, for example, bacteria may be proliferated, and the flow path may be blocked due to the generation of slime due to this. . In order to eliminate such a fear, in a conventional device,
Although a special sterilizer may be installed in the concentrated water circulation system,
Such measures increase the cost and complicate the management and control system accompanying the addition of the sterilizer.

Further, in order to supply the concentrated water to the concentrated water circulation system of the electric regeneration type desalination apparatus 106, the reverse osmosis membrane apparatus 1 is usually used.
Although the permeated water treated in step 04 is used, the amount of water used as make-up water of the concentrated water depends on the reverse osmosis membrane device 1
It is only about 10% of the permeated water (treated water) of No. 04.
That is, the reverse osmosis membrane device 104 also processes and manufactures the concentrated water supplied to the concentrated water circulation system of the electric regeneration type desalination device 106, but the water actually supplied as the concentrated water makeup water Although the amount is small, a large amount of water to be treated including concentrated water returned from the cross-flow type membrane separation device 116 is to be treated. Therefore, from this viewpoint, the efficiency of the treatment in the reverse osmosis membrane device 104 is low.

In view of the above-mentioned various problems in the conventional system, the object of the present invention is to improve the water utilization rate of the whole system and reduce the production cost of ultrapure water finally produced. In addition, the present invention provides an ultrapure water production apparatus that can efficiently suppress the generation of slime and the like in the concentrated water circulation system of the electric regeneration type desalination apparatus and can operate the reverse osmosis membrane apparatus and the like efficiently. Is to do.

[0010]

In order to solve the above-mentioned problems, a pure water producing apparatus according to the present invention is a reverse osmosis membrane apparatus for treating water to be treated, and treating the permeated water of the reverse osmosis membrane apparatus. An electric regeneration type desalination device, an ultraviolet irradiation device for treating water treated by the electric regeneration type desalination device, and a cross-flow type membrane separation device for treating water treated by the ultraviolet irradiation device. A concentrated water recovery line for returning at least a part of the concentrated water of the membrane separation device to the inlet side of the electric regeneration type desalination device. As the raw water (water to be treated) to be supplied, well water, city water, industrial water, or the like, or collected wastewater from a place where ultrapure water is used can be used.

[0011] The concentrated water recovery line from the cross-flow type membrane separation apparatus has a line to the desalination chamber of the electric regeneration type desalination apparatus and a line to the concentrated water circulation system at the inlet side of the electric regeneration type desalination apparatus. It is also possible to connect at least a part of the concentrated water of the cross-flow type membrane separation device to the concentrated water circulation system of the electric regeneration type desalination device, although it is possible to connect it to the part before branching. Thus, it is preferable to be connected at least to the concentrated water circulation system of the electric regeneration type desalination apparatus.

It is preferable that an electrolyte adding means is connected to the concentrated water circulation system of the electric regeneration type desalination apparatus.
The concentrated water from the cross-flow type membrane separator has very low impurity content and extremely low electrical conductivity, so if it is used as it is as the concentrated water in the electric regeneration type desalination unit, it will be circulated. The electrical resistance of the concentrated water becomes too high (that is, close to an insulated state), making it difficult to supply a desired current in the electric regeneration type desalination apparatus, or increasing the applied voltage to supply the predetermined current. May need to be raised. However, by adding the electrolyte to the concentrated water circulating system of the electric regeneration type desalination apparatus, the conductivity of the circulated concentrated water can be increased, and a predetermined desalination treatment can be easily performed.

The electrolyte to be added includes acids, alkalis,
Although any of salts can be used, especially when an acid is added, prevention of scale generation in the concentrated water circulation system can be achieved at the same time. In order to prevent scale generation, it is preferable to adjust the pH to a range of 1.5 to 5.5 by adding an acid.

[0014] The concentrated water of the electric regeneration type desalination apparatus to which the pH has been adjusted by adding the acid as described above can be used more effectively, rather than merely discharging a part thereof. For example, when a part of the concentrated water in the concentrated water circulation system of the electric regeneration type desalination apparatus is combined with the water to be treated supplied to the reverse osmosis membrane apparatus, the reverse osmosis membrane of the reverse osmosis membrane apparatus is deposited on the membrane surface. The effect of suppressing the generation of substances (scale) can be obtained, which can contribute to the improvement of the processing efficiency of the reverse osmosis membrane device. When a decarbonation device is provided on the upstream side of the reverse osmosis membrane device, a part of the concentrated water in the concentrated water circulation system of the electric regeneration type desalination device is combined with the water to be treated supplied to the decarbonation device. be able to. In this way, the carbon dioxide dissolved in the form of ions in the water to be treated supplied to the decarbonation apparatus is converted into a dissolved gas (free carbon dioxide), which is brought into gas-liquid contact to perform degassing. Efficiency can be improved.

In the pure water producing apparatus according to the present invention as described above, at least a part of the concentrated water of the cross-flow type membrane separation device is not supplied to the reverse osmosis membrane device through the concentrated water recovery line but to the inlet side of the reverse osmosis membrane device. The concentrated water from the cross-flow type membrane separation device, which is returned to the inlet side of the electric regeneration type desalination device, should be effectively used as concentrated water in the concentrated water circulation system of the electric regeneration type desalination device. Becomes possible. If it is effectively used as concentrated water in the concentrated water circulation system of the electric regeneration type desalination equipment, a large amount of discharge from the reverse osmosis membrane equipment will be eliminated as in the case of returning to the inlet side of the reverse osmosis membrane equipment, so ultraviolet irradiation Regardless of the device or the reverse osmosis device, the water utilization rate is greatly improved. By improving the water utilization rate, the power consumption of the ultraviolet irradiation device with respect to the unit amount of finally supplied ultrapure water is reduced, and the production cost of ultrapure water is reduced. In addition, since the amount of treatment in the reverse osmosis membrane device with respect to the unit amount of ultrapure water finally supplied is also reduced, the number of elements in the reverse osmosis membrane device can be reduced and the life of each element can be extended, From this aspect as well, the production cost of ultrapure water is reduced.

Further, in the above system, if an electrolyte is added to the concentrated water circulating system of the electric regeneration type desalination apparatus, the conductivity of the concentrated water can be appropriately controlled to ensure the smooth operation of the electric regeneration type desalination apparatus. If an acid is selected as the added electrolyte, an effect of suppressing slime generation in the concentrated water circulation system can be obtained. Furthermore, part of the concentrated water to which the acid has been added can be effectively used by being combined with the inlet side of the reverse osmosis membrane device and the inlet side of the decarbonation device, thereby preventing scale generation on the reverse osmosis membrane. Also, the efficiency of the decarboxylation treatment can be improved.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the pure water producing apparatus of the present invention will be described below with reference to the drawings. FIG. 1 shows a pure water production apparatus according to a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a system of the entire pure water production apparatus, and the supplied treated water 2 is:
First, a pretreatment is performed in the filtration device 3 and the decarbonation device 4.
The filtering device 3 includes, for example, a sand filtering device, and removes suspended impurities and the like by filtration. The decarbonation device 4 includes a decarbonation tower and a membrane deaerator, and removes carbon dioxide gas dissolved in the water to be treated in a state of being saturated or higher. This decarbonation device 4
May be installed as necessary, and may be omitted in some cases. The water to be treated thus pretreated is introduced into the reverse osmosis membrane device 5, where particulate and ionic impurities are removed. The non-permeated water in the reverse osmosis membrane device 5 is discharged as concentrated waste water 6, and the permeated water is sent to the electric regeneration type desalination device 7. Electric regeneration type desalination equipment 7
Then, most of the remaining ionic impurities in the water to be treated are removed. The electric regeneration type desalination apparatus 7 circulates a desalting chamber 8 filled with an ion exchanger (for example, an ion exchange resin) and a concentrated water separated from the desalting chamber 8 by an ion exchange membrane. It has a concentration chamber 9 and an electrode chamber 10 formed in an electrode arrangement portion. The to-be-treated water is passed through the desalting chamber 8 and an appropriate current is passed, whereby ions in the to-be-treated water are moved to the concentrating chamber 9 via the ion exchange membrane, and the desalting treatment is performed. In the present embodiment, the concentrated water circulated in the concentration chamber 9 and the electrode water circulated in the electrode chamber 10 are shared circulation paths. The concentrated water circulating system 11 is provided with a circulating pump 12 and a concentrated water tank 13. From the concentrated water circulating system 11, concentrated water is appropriately drained to adjust the concentration of by-product chlorine and ozone components. Is discharged as The treated water from the electric regeneration type desalination device 7 is temporarily stored in the pure water tank 15. The system up to this point constitutes a so-called primary pure water system for producing ordinary pure water.

The water stored in the pure water tank 15 is supplied to a so-called secondary pure water system, and is produced into ultrapure water by processing in the secondary pure water system. The water from the pure water tank 15
It is supplied to an ultraviolet irradiation device 16 and irradiated with ultraviolet light of a predetermined wavelength to perform a treatment such as sterilization. As the wavelength of the ultraviolet ray, for example, a wavelength of 254 nm or a wavelength in the vicinity thereof is selected, so that an efficient sterilization treatment can be performed.
In addition, by containing ultraviolet rays having a wavelength of 185 nm or a wavelength near 185 nm, it becomes possible to oxidize organic substances and decompose them into carbonic acid and organic substances. The treated water from the ultraviolet irradiation device 16 is supplied to the cartridge type polisher 17, where ions and the like in the treated water are finally removed. This cartridge type polisher 17 is configured as a disposable type filled with an ion exchange resin, and is exchanged according to a use condition.

The treated water from the cartridge-type polisher 17 is supplied to a cross-flow type membrane separation device 18 where fine foreign substances (particles) in the water to be treated are finally removed and permeated. Water is produced as ultrapure water. The produced ultrapure water is supplied to each use place 19. As the cross-flow type membrane separation device 18, any device capable of separating fine particles through a membrane may be used, and an ultrafiltration membrane device, a microfilter device, a reverse osmosis membrane device, or the like can be used. In the secondary pure water system including the cross-flow type membrane separation device 18, if the operation is stopped, the quality of the treated water may not be stabilized due to the accumulation of impurities on the membrane surface or the growth of microorganisms on the membrane surface. A constant amount of treated water is always returned to the pure water tank 15 through the circulation line 20 so that the operation is continuously performed for the purpose of achieving the desired efficiency and the supply amount to the use location 19 can be changed. .

At least a part of the concentrated water in the cross-flow type membrane separation device 18, in the embodiment shown in FIG. 1, substantially the entire amount thereof is returned to the inlet side of the electric regeneration type desalination device 7 via the concentrated water recovery line 21. Have been. In the present embodiment, the concentrated water recovery line 21 is connected to the treated water line 22 from the reverse osmosis membrane device 5, and after being combined with the permeated water from the reverse osmosis membrane device 5, most of the combined water is The water is supplied to the desalination chamber 8 of the electric regeneration type desalination device 7 via the line 23, and a part is supplied to the concentrated water tank 13 of the concentrated water circulation system 11 via the line 24. .

In the pure water producing apparatus 1 according to the first embodiment thus configured, the concentrated water returned from the cross flow type membrane separation device 18 via the concentrated water recovery line 21 is subjected to reverse osmosis. Since the concentrated water that has been returned is not returned to the inlet side of the membrane device 5, the returned concentrated water is not treated again by the reverse osmosis membrane device 5 and discharged in large quantities as non-permeated water in the reverse osmosis membrane device 5. As a result, in particular, the amount of water discharged from the system out of the water treated by the ultraviolet irradiation device 16 is greatly reduced as compared with the conventional device shown in FIG. Manufacturing cost is reduced. In addition, since the returned concentrated water is not reprocessed in the reverse osmosis membrane device 5, the processing amount in the reverse osmosis membrane device 5 is reduced as compared with the conventional device shown in FIG.
The number of elements of the reverse osmosis membrane device 5 can be reduced and the life of each element can be extended, so that the production cost of ultrapure water can also be reduced. Then, a part of the returned concentrated water is supplied to the concentrated water circulation system 11 of the electric regeneration type desalination device 7,
Used effectively.

FIG. 2 shows a pure water producing apparatus 31 according to a second embodiment of the present invention. In this embodiment, as compared with the first embodiment shown in FIG. 1, the concentrated water recovery line 32 from the cross-flow type membrane separation device 18 is connected to at least the concentrated water circulation system 11 of the electric regeneration type desalination device 7. The concentrated water that is directly connected and recovered is returned to the concentrated water tank 13 in the present embodiment.
However, as described above, since the amount of water to be replenished to the concentrated water circulation system 11 of the electric regeneration type desalination device 7 is small, the concentrated water from the cross-flow type membrane separation device 18 is usually supplied to the concentrated water circulation system 11. Will be left over for water to be replenished.
This extra amount of recovered water may, for example, be combined with the feed water in line 23 to desalination chamber 8 via line 33 and, in some cases, to reverse osmosis membrane device 5 via line 34 May be combined with the supplied water to be treated. In any case, the water utilization is improved as compared with the conventional apparatus shown in FIG.

In the first embodiment shown in FIG. 1, the recovered cross-flow type membrane separation device 1 is used.
Although there is a possibility that the particles contained in the concentrated water from the concentrated water 8 may be insufficiently discharged, in the pure water production apparatus 31 according to the second embodiment, the concentrated water circulation system 11 of the electric regeneration type desalination apparatus 7 is used. Particles can be discharged using the waste water 14 from the wastewater, so that sufficient discharge is possible.

Further, the cross-flow type membrane separation device 18
Concentrated water supplied from the regenerating desalination unit 7 to the concentrated water circulation system 11 of the electric regeneration type desalination unit 7
Water that has been sterilized by an electric regeneration desalination unit 7
Of slime in the concentrated water circulation system 11 is prevented.
Therefore, for a long period of time, the electric regeneration type desalination device 7
The stable operation of is continued. Other configurations, operations, and effects are the same as those of the first embodiment.

FIG. 3 shows a pure water producing apparatus 41 according to a third embodiment of the present invention. In this embodiment, as compared with the second embodiment shown in FIG. 2 described above, the concentrated water circulating system 11 of the electric regeneration type desalination apparatus 7 is further provided with an electrolyte adding means 42.
Is connected. As the electrolyte to be added, any electrolyte can be used as long as the conductivity of the circulated concentrated water can be increased and adjusted to a desired value, and any of acids, alkalis, and salts can be used. For example, when an acid is added, the pH is 1.5
It is preferable to control the injection amount so as to be in the range of 5.5 to 5.5.

The concentrated water circulation system 11 of the electric regeneration type desalination unit 7
By adding an electrolyte to the water, the conductivity of the circulated concentrated water can be increased and controlled to an optimum value, and a predetermined current can be applied by applying a relatively low voltage, and electric regeneration can be performed. The desired desalination treatment in the desalination apparatus 7 can be performed more smoothly and efficiently. Therefore,
The quality of the ultrapure water finally produced can be improved, the desalination process can be performed with low power, and the production cost of the ultrapure water can be further reduced.

If an acid is used as the electrolyte to be added, the scale can be dissolved by lowering the pH on the membrane surface of the concentration chamber 9 of the electric regeneration type desalination apparatus 7, and the concentrated water circulation system 11 can be used. In addition to the prevention of slime generation, the prevention of scale generation can be achieved, and the concentrated water circulation system 11
Is more reliably prevented. Other configurations, operations, and effects are similar to those of the first embodiment and the second embodiment.

FIG. 4 shows a pure water producing apparatus 51 according to a fourth embodiment of the present invention. In this embodiment, as compared with the third embodiment shown in FIG. 3, the electrolyte adding means is constituted by the acid adding means 52 and the concentrated water circulation system 1
Part of the acid-added concentrated water in 1
It is introduced into the inlet side of the reverse osmosis membrane device 5 through 3 and is joined to the water to be treated supplied to the reverse osmosis membrane device 5.

As described above, by adding a part of the concentrated water to which the acid is added in the concentrated water circulation system 11 to the water to be treated supplied to the reverse osmosis membrane device 5, the same operation as in the concentrated water circulation system 11 is achieved. Thereby, the generation of precipitates (scale) on the reverse osmosis membrane device of the reverse osmosis membrane device 5 can be suppressed, the processing efficiency of the reverse osmosis membrane device 5 is improved, and the life of the reverse osmosis membrane is extended. Will be extended. As described above, the concentrated water recovered from the cross-flow type membrane separation device 18 is effectively used for the concentrated water circulation system 11 of the electric regeneration type desalination device 7, and is subjected to appropriate treatment there to further perform reverse osmosis membrane. It can be effectively used for the treated water supply system of the device 5, and can be effectively used in two stages. Other configurations, operations, and effects are in accordance with the first embodiment, the second embodiment, and the third embodiment.

FIG. 5 shows a pure water production apparatus 61 according to a fifth embodiment of the present invention. In this embodiment, the concentrated water circulation system 11 is different from the fourth embodiment shown in FIG.
A part of the acid-added concentrated water in
And is introduced into the inlet side of the decarbonation device 4 through the, and is combined with the water to be treated supplied to the decarbonation device 4.

As described above, a part of the concentrated water to which the acid is added in the concentrated water circulating system 11 is combined with the water to be treated supplied to the decarbonation apparatus 4, so that the treated water supplied to the decarbonation apparatus 4 is mixed. Carbonic acid dissolved in water in the form of ions is converted into a dissolved gas (free carbonic acid), which is brought into gas-liquid contact in the decarbonation device 4, thereby improving the efficiency of the degassing process. Therefore, the efficiency of the subsequent steps, and finally the quality of the ultrapure water finally produced, are further improved. Also in the fifth embodiment, the concentrated water recovered from the cross-flow type membrane separation device 18 is effectively used for the concentrated water circulation system 11 of the electric regeneration type desalination device 7 and then subjected to appropriate treatment. Furthermore, it can be effectively used for the water supply system of the decarbonation apparatus 4 and can be effectively used in two stages. Other configurations, operations, and effects conform to the first to fourth embodiments.

[0032]

As described above, according to the pure water production apparatus of the present invention, the concentrated water from the cross-flow type membrane separation apparatus is supplied to the inlet of the electric regeneration type desalination apparatus in comparison with the conventional pure water production system. By collecting the water to the side, the water utilization rate of the entire system can be greatly improved, and the production cost of the ultrapure water finally produced can be significantly reduced.

In particular, by collecting the concentrated water from the cross-flow type membrane separation device in the concentrated water circulation system of the electric regeneration type desalination device, it is possible to efficiently suppress the generation of slime and scale in the concentrated water circulation system. Efficient and stable operation of the regenerative desalination device can be achieved, and the production cost of ultrapure water can be further reduced by reducing the operation cost of the electric regenerative desalination device.

Further, by adding an electrolyte, especially an acid, to the concentrated water circulating system of the electric regeneration type desalination apparatus, it is possible to solve the problem in the concentrated water circulating system. To improve the efficiency of the entire system and the quality of the ultrapure water that is finally produced by combining the water with the feedwater system of a reverse osmosis membrane device or a decarbonation device. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic system diagram of a pure water production apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic system diagram of a pure water production apparatus according to a second embodiment of the present invention.

FIG. 3 is a schematic system diagram of a pure water production apparatus according to a third embodiment of the present invention.

FIG. 4 is a schematic system diagram of a pure water production apparatus according to a fourth embodiment of the present invention.

FIG. 5 is a schematic system diagram of a pure water production apparatus according to a fifth embodiment of the present invention.

FIG. 6 is a schematic system diagram of a conventional pure water production apparatus.

[Explanation of symbols]

1, 31, 41, 51, 61 Pure water production equipment 2 Water to be treated 3 Filtration equipment 4 Decarbonation equipment 5 Reverse osmosis membrane equipment 6 Drainage 7 Electric regeneration type desalination equipment 8 Desalination room 9 Concentration room 10 Electrode room 11 Concentration Water circulation system 12 Circulation pump 13 Concentrated water tank 14 Drainage 15 Pure water tank 16 Ultraviolet irradiation device 17 Cartridge type polisher 18 Cross flow type membrane separation device 19 Place of use 20 Circulation line 21, 32 Concentrated water recovery line 22 From reverse osmosis membrane device Treated water line 23 Line to desalination chamber 24 Line to concentrated water circulation system 33 Line connected to line to desalination chamber 34 Line connected to inlet side of reverse osmosis membrane device 42 Electrolyte adding means 52 Acid adding means 53 A line connected from the concentrated water circulation system to the inlet side of the reverse osmosis membrane device. 62 A line connected from the concentrated water circulation system to the inlet side of the decarbonation unit. The line

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C02F 1/469 C02F 9/00 502D 9/00 502 502Z 502F 502L 502N 502J 502K 502E 503B 503 504E 504 1/46 103F Term (Reference) 4D006 GA03 GA06 GA07 GA17 KA52 KB01 KB04 KB11 KB15 KB17 MA12 PA01 PB02 PB05 PB06 PB26 PB64 PC02 4D037 AA03 AB03 AB11 BA18 BA23 CA02 CA03 CA04 CA15 4D061 DA02 DB13 EA02 EA09 EB04 EB13 EB39 ED39 GC12

Claims (6)

[Claims] 1. A reverse osmosis membrane device for treating water to be treated, an electric regeneration type desalination device for treating permeated water of the reverse osmosis membrane device, and an ultraviolet ray for treating treated water of the electric regeneration type desalination device. An irradiation device, and a cross-flow type membrane separation device for treating water treated by the ultraviolet irradiation device, wherein at least a part of the concentrated water of the cross-flow type membrane separation device is provided at an inlet side of the electric regeneration type desalination device. A pure water production apparatus, characterized by having a concentrated water recovery line for returning to a concentrated water. 2. The pure water production apparatus according to claim 1, wherein the concentrated water recovery line is connected to at least a concentrated water circulation system of the electric regeneration type desalination apparatus. 3. The pure water production apparatus according to claim 2, wherein an electrolyte addition means is connected to a concentrated water circulation system of the electric regeneration type desalination apparatus. 4. The pure water production apparatus according to claim 3, wherein said electrolyte adding means comprises means for adding an acid. 5. The pure water production according to claim 4, further comprising a piping line for joining a part of the concentrated water in the concentrated water circulation system of the electric regeneration type desalination device to the water to be treated supplied to the reverse osmosis membrane device. apparatus. 6. A treatment water having a decarbonation device upstream of the reverse osmosis membrane device and a part of concentrated water in a concentrated water circulation system of the electric regeneration type desalination device being supplied to the decarbonation device. The pure water production apparatus according to claim 4, further comprising a piping line that joins the water.