Ultra-pure water production method and ultra-pure water production apparatus

Abstract

To provide brackish water available as raw water used for ultrapure water production.SOLUTION: An ultra pure water production method includes a pretreatment to remove suspended solids from raw water containing brackish water 24 to obtain pretreated water, a primary treatment to remove all organic carbon and ionic components in the pretreated water to produce primary pure water, and secondary treatment to remove impurities in the primary pure water to produce ultra pure water, and the boron concentration of the raw water is adjusted so that it is less than the allowable value calculated from the boron concentration required for the ultrapure water.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for producing ultrapure water and an apparatus for producing ultrapure water.

Background Art

[0002] In an ultrapure water production apparatus that supplies ultrapure water to semiconductor manufacturing equipment and the like, a technique is disclosed that uses tap water as raw water and the drainage of ultrapure water used in semiconductor manufacturing and the like (sometimes referred to as recovered water) (see Patent Documents 1-7).

[0003] Generally, recovered water was originally ultrapure water, to which substances used in semiconductor manufacturing, such as acids, alkalis, IPA (isopropyl alcohol), surfactants, CMP abrasives, etc., are mixed. Therefore, the components are relatively clear, and it is relatively easy to treat this and mix it with the raw water for use.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, since a large amount of ultrapure water is used in the manufacture of semiconductors and the like, the amount of raw water used in the production of ultrapure water is also increasing. Since the supply of raw water is limited, measures are required to reduce the amount of raw water used in ultrapure water production so that there is no shortage of raw water for other uses. In addition, since the utilization of the recovered water also has limitations, although it has the effect of reducing the use of raw water, it cannot fully cope with the current enlargement of semiconductor manufacturing plants and the like. In addition, due to the current environmental problems and climate change problems, the supply of raw water is becoming unstable, and there is a need to secure a new raw water source.

[0006] As a new raw water source, brackish water existing in the boundary area between rivers and the sea is considered. The brackish water is mixed with boron contained in seawater, and its water quality fluctuates greatly due to the influence of tidal currents. However, it has been difficult for conventional ultrapure water production equipment to sufficiently remove boron from such brackish water. When installing equipment for removing boron from brackish water, if the performance of the equipment is adjusted to seawater with a high boron concentration, the equipment will be excessive for brackish water, increasing the cost of ultrapure water production. On the other hand, if the performance of the equipment is adjusted to river water with a low boron concentration, it will not be able to cope with the case where the boron concentration of brackish water increases to the seawater level, resulting in an inability to stably supply raw water, and as a result, it becomes difficult to stably supply ultrapure water for semiconductor manufacturing. The semiconductor manufacturing process and the like often continue operating on an annual basis, and a stable supply of ultrapure water is essential on an annual basis. Therefore, it has not been common to use brackish water as the raw water for ultrapure water for semiconductor manufacturing and the like.

[0007] An object of the present invention is to enable the use of brackish water as the raw water used in ultrapure water production.

Means for Solving the Problems

[0008] The method for producing ultrapure water according to the first aspect includes a pretreatment for removing suspended substances from raw water containing steam water to obtain pretreated water, a primary treatment for removing all organic carbon components and ionic components in the pretreated water to produce primary pure water, and a secondary treatment for removing impurities in the primary pure water to produce ultrapure water, and adjusts the boron concentration of the steam water so as to be equal to or lower than an allowable value calculated from the boron concentration required for the ultrapure water.

[0009] In this method for producing ultrapure water, since the boron concentration of the steam water is adjusted to be equal to or lower than the allowable value calculated from the boron concentration required for the ultrapure water, the steam water can be used as the raw water. When using steam water and tap water as the raw water, the amount of tap water used can be suppressed as compared with the case of using only tap water as the raw water.

[0010] The second aspect is the method for producing ultrapure water according to the first aspect, and when the boron concentration of the steam water exceeds the allowable value, a pretreatment for removing boron contained in the steam water is performed before the pretreatment.

[0011] In this method for producing ultrapure water, when the boron concentration of the steam water exceeds the allowable value, the boron concentration of the steam water can be reduced to be equal to or lower than the allowable value by removing the boron contained in the steam water by a pretreatment further before the pretreatment. Also, thereby, the steam water can be used as the raw water for producing ultrapure water.

[0012] The third aspect is the method for producing ultrapure water according to the second aspect, wherein the pretreatment includes a primary pretreatment that is always performed and a secondary pretreatment that is performed when the boron concentration of the steam water exceeds a predetermined value.

[0013] In this method for producing ultrapure water, by switching between the case of using only the primary pretreatment and the case of using both the primary pretreatment and the secondary pretreatment, it is possible to flexibly respond to changes in the boron concentration of the steam water due to the tidal current. Also, thereby, the operation cost can be suppressed.

[0014] The ultrapure water production apparatus according to the fourth aspect includes a pretreatment apparatus that removes suspended substances in raw water containing steam water to obtain pretreatment water, a primary pure water apparatus that removes all organic carbon components and ion components in the pretreatment water to produce primary pure water, a secondary pure water apparatus that removes impurities in the primary pure water to produce ultrapure water, and a measurement unit that measures the boron concentration of steam water. The boron concentration of the steam water is adjusted so as to be equal to or lower than an allowable value calculated from the boron concentration required for the ultrapure water.

[0015] In this ultrapure water production apparatus, since the boron concentration of the steam water is adjusted so as to be equal to or lower than the allowable value calculated from the boron concentration required for the ultrapure water, steam water can be used as the raw water. When using steam water and tap water as the raw water, the amount of tap water used can be suppressed compared to the case of using only tap water as the raw water.

[0016] The fifth aspect is the ultrapure water production apparatus according to the fourth aspect, which includes a pretreatment apparatus that removes boron from steam water.

[0017] In this ultrapure water production apparatus, when the boron concentration of the steam water exceeds the allowable value, the boron contained in the steam water can be removed by a preliminary pretreatment before the pretreatment, so that the boron concentration of the steam water can be reduced to be equal to or lower than the allowable value. Also, thereby, steam water can be used as the raw water for ultrapure water production.

[0018] The sixth aspect is the ultrapure water production apparatus according to the fifth aspect, wherein the pretreatment apparatus includes a primary pretreatment apparatus that is always used and a secondary pretreatment apparatus that is performed when the boron concentration of the steam water exceeds a predetermined value.

[0019] In this ultrapure water production apparatus, by switching between the case of using only the primary pretreatment apparatus and the case of using the primary pretreatment and the secondary pretreatment apparatus, it is possible to flexibly respond to changes in the boron concentration of the steam water due to the tide. Also, thereby, the operation cost can be suppressed.

Advantages of the Invention

[0020] According to the present invention, brackish water can be used as raw water for producing ultrapure water.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0022] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. Components denoted by the same reference numerals in each drawing mean the same or similar components. In the embodiments described below, redundant descriptions and reference numerals may be omitted. Also, the drawings used in the following description are all schematic, and the dimensional relationships of the respective elements shown in the drawings, the ratios of the respective elements, etc. do not necessarily match the actual ones. Also, the dimensional relationships of the respective elements, the ratios of the respective elements, etc. do not necessarily match among a plurality of drawings.

[0023] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

[0024] In FIG. 1, the ultrapure water production apparatus 100 according to the present embodiment can receive brackish water existing in the boundary region between a river and the sea and produce ultrapure water. This ultrapure water production apparatus 100 includes a pretreatment apparatus 10, a primary pure water apparatus 11, a secondary pure water apparatus 12, and a measurement unit 30. Here, the brackish water refers to river water whose water quality concentration varies periodically under the influence of tidal currents, particularly river water in which the ratio of the concentration at high concentration times to that at low concentration times is 2 times or more, or 4 times or more.

[0025] The pretreatment apparatus 10 is an apparatus that removes suspended substances in raw water containing brackish water 24 to obtain pretreated water. As an example, sand filtration filled with media such as filter sand, a packed bed filtration tower such as an MMF (multimedia filter tower), a membrane filtration apparatus using filters such as an MF (microfilter) and a UF (ultrafiltration membrane), and / or a granular activated carbon tower, etc. are used to filter impurities such as residual chlorine and large dust in the raw water. The raw water such as tap water 14 is tap water, industrial water, well water, and recycled water. Tap water is so-called city water obtained by subjecting natural water such as river water, lake water, and well water to a coagulation sedimentation process and a filtration process in a water treatment plant. The boron concentration of tap water is, for example, 40 μg / L (conductivity 200 μS / cm) or less. Industrial water, well water, and recycled water generally have the same water quality as tap water. The raw water such as tap water 14 is stored as raw water in, for example, a PIT 20 which is a raw water tank and used for ultrapure water production.

[0026] The primary pure water production device 11 is a device that removes total organic carbon (TOC) components and ionic components in the pretreated water to produce primary pure water. As an example, it combines a reverse osmosis membrane device that reverse-osmoses pretreated water using a semipermeable membrane, an ion exchange resin device filled with ion exchange resin, an electro-deionization device (EDI), an ultraviolet irradiation device that decomposes organic substances, a degassing membrane device that degasses dissolved gas, etc. to purify primary pure water. The primary pure water production device 11 may be provided with, for example, a high-pressure reverse osmosis membrane device, a urea decomposition device such as an oxidation reaction tank that decomposes urea by adding hypobromous acid, etc., as necessary. Note that the ion exchange resin device is filled with cation exchange resin and anion exchange resin in any of the single-bed, double-bed, or mixed-bed systems, but may contain boron-selective ion exchange resin as necessary. As the ion exchange resin device, a boron-selective ion exchange resin device may be installed alone. The produced primary pure water is supplied to the pure water tank 22.

[0027] The secondary pure water production device 12 is a device that further removes impurities in the primary pure water to produce ultrapure water. For example, it removes inorganic ions contained in trace amounts in the primary pure water by, for example, a non-regenerative ion exchange column (polisher). Furthermore, an ultraviolet irradiation device, a hydrogen peroxide decomposition device, a degassing device, etc. are combined. An ultrafiltration membrane is installed at the end of the secondary pure water production device 12 to remove fine particles. The produced ultrapure water is supplied to the POU (Point Of Use) 19, used for semiconductor manufacturing, etc., and a part of it is circulated to the pure water tank 22 through the circulation line 28.

[0028] The measurement unit 30 is, for example, a boron meter or a conductivity meter for measuring the boron concentration of the steam-water 24. The liquid to be measured by the boron meter is not limited to the steam-water 24, and it is possible to use the steam-water treated by the pretreatment device 13, the ultrapure water obtained by the secondary pure water production device 12, and the liquids obtained in each intermediate process of the other ultrapure water production device 100 as the liquid to be measured. In order to measure the boron concentration of the steam-water that has passed through the pretreatment device 13, a boron meter 31 may be provided on the downstream side of the pretreatment device 13.

[0029] In order to adjust the boron concentration of the brackish water 24 to be equal to or less than the allowable value calculated from the boron concentration required for ultrapure water, this embodiment may further include a pretreatment device 13 for removing boron from the brackish water 24. The boron concentration required for ultrapure water in the POU 19 is, for example, 0.5 μg / L. The allowable value calculated from this in consideration of the boron removal performance of the pretreatment device 13 is, for example, 100 μg / L in the state before entering the pretreatment device 13.

[0030] The brackish water 24 assumed in this embodiment is, for example, river water taken from a position about 6 km upstream from the estuary. FIG. 2 shows an example of the change in the boron concentration of the brackish water over time at that position. Due to tidal level changes, the boron concentration of the brackish water rises above 100 μg / L twice in 24 hours. Also, the conductivity of the brackish water rises in synchronization with the change in the boron concentration. The conductivity corresponding to a boron concentration of 100 μg / L is 800 μS / cm. Hereinafter, the boron concentration is used as a reference. In this embodiment, when the boron concentration exceeds 100 μg / L, the pretreatment device 13 is used to reduce the boron concentration of the brackish water to 100 μg / L or less. The pretreatment device 13 preferably includes boron removal means. Specifically, for example, the following means can be used as the pretreatment device 13.

[0031] 1) High-pressure reverse osmosis membrane device (high-pressure RO) 2) (RO)-boron selective ion exchange resin device 3) High-pressure RO-boron selective ion exchange resin device 4) RO-alkali addition-RO 5) RO-ion exchange resin (anion exchange resin) device 6) 2B3T device (cation tower-DG-anion resin tower)

[0032] In the means of 1, although the boron removal rate is slightly low, all substances containing boron can be removed. High-pressure RO indicates a high-pressure reverse osmosis membrane device. Since high-pressure RO has a high boron removal rate, it can be a boron removal means. As the high-pressure RO, existing high-pressure ROs can be used. Specifically, examples include the SWC series (manufactured by HYDEANAUTICS), the TM800 series (manufactured by Toray Industries, Inc.), the SW series (manufactured by Dow Chemical Company), etc.

[0033] In the means of 2, since the boron-selective ion exchange resin device removes only boron, it is desirable to use RO complementarily. The parentheses "(RO)" mean that RO may not be used. The boron-selective ion exchange resin is an ion exchange resin having an n-methylglucamine group. Examples include CRB02, CRB03, CRB05 (manufactured by Mitsubishi Chemical Corporation), Amberlite IRA743 (registered trademark; Rohm and Haas Company), etc. The boron-selective ion exchange resin selectively adsorbs boron regardless of the salt concentration, so boron can be removed regardless of the salt concentration and preferably functions as a pretreatment device.

[0034] According to the integrated value of water quality × time in the case of water quality exceeding 100 ug / L in Figure 2, determine the amount of boron resin (BTC: through-flow exchange capacity) in advance. The boron resin is regenerated after the water flow is completed. If the amount of boron resin is the capacity of two peaks, for example, it can be regenerated once a day. It is preferable to determine the amount of boron resin so that it is regenerated once every 1 to 20 days.

[0035] Also, instead of the boron-selective ion exchange resin, it is also possible to use an inorganic boron adsorbent. Specifically, there are cerium-based adsorbents such as READ-B (manufactured by Nippon Suishitsu Co., Ltd.). Hereinafter, the description of the boron-selective ion exchange resin shall also include inorganic boron adsorbents.

[0036] RO indicates ultra-low pressure RO and low pressure RO. In both cases, existing ROs can be applied. Although these ROs have low boron removal performance, they have high removal capabilities for common salts, turbidity, etc. Therefore, in the second method, it functions as a pretreatment device to remove substances that may reduce the function of the subsequent boron-selective ion exchange resin device.

[0037] In the third method, high pressure RO is used. In this case, if the boron concentration in the feed water 24 exceeds 500 μg / L, the feed water 24 can be supplied to the cooling tower 34 and used as cooling tower water. The resin amount and regeneration of the boron-selective ion exchange resin device are the same as those in the second method.

[0038] In the fourth method, the boron removal rate of the subsequent RO can be increased by adding alkali. That is, in the fourth method, alkali addition + RO functions as a boron removal means. ROs equivalent to those in the second method can be applied.

[0039] In the fifth method, generally boron breaks through the anion exchange resin immediately, but it functions well for a short period. That is, in the fifth method, the anion exchange resin functions as a boron removal means. Since the regeneration of the anion exchange resin can be carried out only with alkali and the operation is easy, it can be preferably used as a pretreatment device as in the present application. ROs equivalent to those in the second method can be applied.

[0040] In the sixth method, since a resin tower is used, there is no clogging like RO and all substances can be removed. 2B3T is a device equipped with a cation resin tower, a deaeration tower, and an anion resin tower in sequence. That is, in the sixth method, the anion exchange resin functions as a boron removal means. Note that since this method removes all ions, the regeneration frequency may be higher than that of the fifth method. However, since the operation time required for the pretreatment device is short, the regeneration frequency will not reach the level where the pretreatment device stops functioning, so it can be used as a pretreatment device.

[0041] In any of the means 1 to 6, since there is a limit to the removal performance of boron or the like, the switching water quality to the cooling tower 34 can be set according to each performance.

[0042] As a method for adjusting the boron concentration of raw water, changing the mixing ratio of tap water 14 and aerated water 24 such as municipal water, or increasing the size of the PIT 20 is also conceivable. If the boron concentration of the aerated water 24 is low, the boron concentration can be kept within the allowable value by increasing the proportion of tap water 14. The change in the mixing ratio of tap water 14 and aerated water 24 such as municipal water can be used to cope with the case where the boron concentration is low, but a special device such as a boron-selective ion exchange resin device for adjusting the boron concentration is not required.

[0043] Also, if the PIT 20 is large, water intake of the aerated water 24 can be stopped during the time period when the boron concentration of the aerated water exceeds the allowable value, and ultrapure water production can be carried out while consuming the raw water with a low boron concentration stored in the PIT 20. During the time period when the boron concentration becomes below the allowable value, the water storage volume of the PIT 20 can be restored by taking in aerated water. In this case, the use of tap water as the raw water may be combined. Also, the capacity of the PIT 20 may be determined in consideration of the tendency of fluctuations in the quality of the aerated water, the supply amount of ultrapure water, and further the usage amount of tap water.

[0044] (Function) In this embodiment, since the boron concentration of the aerated water Raw water containing is adjusted to be below the allowable value calculated from the boron concentration required for ultrapure water, the aerated water can be used as the raw water. When using the aerated water and tap water as the raw water, the usage amount of tap water can be suppressed compared to the case of using only tap water as the raw water.

[0045] Also, when the boron concentration of the aerated water exceeds the allowable value, the boron contained in the aerated water can be removed by pre-treatment further before the pre-treatment, so that the boron concentration of the aerated water can be reduced to below the allowable value. Also, thereby, the aerated water can be used as the raw water for ultrapure water production.

[0046] According to this embodiment, the aerated water can be made available as the raw water used for ultrapure water production.

[0047] [Second Embodiment] The raw water 24 assumed by the ultrapure water production apparatus 200 according to this embodiment is, for example, river water taken from a position about 4 km upstream from the river mouth. FIG. 4 shows an example of the change in the boron concentration of the raw water over time at that position. Since the water intake position is closer to the river mouth than in the case of FIG. 2, the boron concentration of the raw water does not fall below 100 μg / L, and the boron concentration of the raw water rises above 500 μg / L twice in 24 hours due to tidal level changes. Further, the conductivity of the raw water increases in synchronization with the change in the boron concentration. The conductivity corresponding to a boron concentration of 100 μg / L is 2700 μS / cm.

[0048] In order to cope with such a boron concentration, in FIG. 3, the ultrapure water production apparatus 200 includes, as a pretreatment apparatus, a primary pretreatment apparatus 13A that is always used, and a secondary pretreatment apparatus 13B that is performed when the boron concentration of the raw water exceeds a predetermined value.

[0049] As the primary pretreatment apparatus 13A, high-pressure RO can be used. This is the same as “1)” of the pretreatment apparatus 13 in the first embodiment. Also, as the primary pretreatment apparatus 13A, RO-alkali addition-low-pressure RO can be used. This is the same as “4)” of the pretreatment apparatus 13 in the first embodiment.

[0050] As the pretreatment apparatus 13B, for example, a boron-selective ion exchange resin apparatus can be used. This is the same as the boron-selective ion exchange resin apparatus in “2)” or “3)” of the pretreatment apparatus 13 in the first embodiment. The amount of boron resin is determined according to the integrated value of water quality×time in the case of water quality exceeding 500 ug / L in FIG. 4. The boron resin is regenerated after the water flow is completed. If the amount of boron resin is the capacity for two peaks, it may be regenerated, for example, once a day. Note that it is preferable to determine the amount of boron resin so as to regenerate once every 1 to 20 days.

[0051] In order to measure the boron concentration of the feed water after passing through the primary pretreatment device 13A, a boron meter 31A may be provided downstream of the primary pretreatment device 13A and upstream of the secondary pretreatment device 13B. Further, in order to measure the boron concentration of the feed water after passing through the secondary pretreatment device 13B, a boron meter 31B may be provided downstream of the secondary pretreatment device 13B.

[0052] In this embodiment, when the boron concentration of the feed water 24 is 500 μg / L or less, boron is removed by the primary pretreatment device 13A that is normally used. When the boron concentration of the feed water 24 exceeds 500 μg / L and is 5000 μg / L or less, the feed water 24 that has passed through the primary pretreatment device 13A is further supplied to the secondary pretreatment device 13B, and boron is removed by the secondary pretreatment device 13B.

[0053] When the primary pretreatment device 13A is RO-alkali addition-low pressure RO, the low pressure RO is operated at pH 10.5 by alkali addition. In this case, if the boron concentration of the feed water 24 exceeds 5000 μg / L, the feed water 24 may be supplied to the cooling tower 34 and used as cooling tower water. In this case, the primary pretreatment device 13A is not used.

[0054] In this ultrapure water production device 200, by switching between the case of using only the primary pretreatment device 13A and the case of using the primary pretreatment device 13A and the secondary pretreatment device 13B, it is possible to flexibly respond to changes in the boron concentration of the feed water due to the tide. Also, this can suppress the operation cost.

[0055] For other parts, since they are the same as those in the first embodiment, the same reference numerals are given in the drawings to the same parts, and the description is omitted.

[0056] [Third Embodiment] The raw water 24 assumed by the ultrapure water production apparatus 300 according to this embodiment is, for example, river water taken from a position about 2 km upstream from the river mouth. FIG. 6 shows an example of the change in the boron concentration of the raw water over time at this position. Since the water intake position is closer to the river mouth than in the case of FIG. 4, the boron concentration of the raw water does not fall below 500 μg / L, and due to the change in the tide level, the boron concentration of the raw water rises above 2000 μg / L twice in 24 hours. Also, in synchronization with the change in the boron concentration, the conductivity of the raw water increases.

[0057] In order to cope with such a boron concentration, in FIG. 5, the ultrapure water production apparatus 300 has a pretreatment apparatus 13. As the pretreatment apparatus 13, for example, a high-pressure RO-boron selective ion exchange resin apparatus can be used.

[0058] Also, as the pretreatment apparatus 13, an ultra-low pressure RO-alkali addition-low pressure RO can be used. In this case, the low pressure RO is operated at pH 10.5 by adding an alkali. In this case, if the boron concentration of the raw water 24 exceeds 5000 ug / L, the raw water 24 may be supplied to the cooling tower 34 and used as the cooling tower water. In this case, the pretreatment apparatus 13 is not used.

[0059] Since the anion resin cannot continuously maintain the removal rate, the anion exchange resin tower and the 2B3T apparatus are not suitable for the pretreatment apparatus 13.

[0060] In this embodiment, the pretreatment apparatus 13 is always in operation, but it is possible to switch between low-load operation and high-load operation according to the quality of the raw water. For example, when the boron concentration of the raw water 24 is 2000 ug / L or less, the low-load operation of the pretreatment apparatus 13 is performed. When performing low-load operation, if the pretreatment apparatus 13 is a high-pressure RO-boron selective ion exchange resin apparatus and there are, for example, two boron selective ion exchange resin towers, one tower may be operated for water flow and the other tower may be regenerated. Or, if there are two systems of this pretreatment apparatus 13, only one system may be used for water flow and the high-pressure RO may be cleaned in the other system.

[0061] When the boron concentration of the steam water 24 exceeds 2000 ug / L and is 5000 ug / L or less, the pre-treatment device 13 is operated at high load to efficiently remove boron.

[0062] For other parts, since they are the same as those in the first embodiment, the same parts are denoted by the same reference numerals in the drawings and the description thereof is omitted.

[0063] [Comparative Example of the Third Embodiment] When the pre-treatment device 13 of the third embodiment is used for seawater, three systems of the pre-treatment device 13 are required. That is, two systems of equipment are always in operation, and another system of equipment for regeneration and standby is required.

[0064] Comparing the third embodiment with the comparative example of the third embodiment, the third embodiment requires one less piece of equipment. Also, in the third embodiment, only one system is operated during low-load operation, while in the comparative example of the third embodiment, two systems are always in operation. Therefore, it is clear that the third embodiment can reduce the installation cost of the equipment and also reduce the operation cost.

[0065] [Ultra-Pure Water Manufacturing Method] The ultra-pure water manufacturing method according to the present embodiment includes a pre-treatment for removing suspended substances in raw water containing steam water to obtain pre-treated water, a primary treatment for removing all organic carbon components and ion components in the pre-treated water to produce primary pure water, and a secondary treatment for removing impurities in the primary pure water to produce ultra-pure water, and the boron concentration of the steam water Raw water containing is adjusted to be equal to or less than an allowable value calculated from the boron concentration required for the ultra-pure water.

[0066] Here, when the boron concentration of the steam water exceeds the allowable value, a pre-treatment for removing boron contained in the steam water may be performed before the pre-treatment.

[0067] Further, the pre-treatment may include a primary pre-treatment that is always performed and a secondary pre-treatment that is performed when the boron concentration of the steam water exceeds a predetermined value.

[0068] [Other Embodiments] As described above, an example of an embodiment of the present invention has been explained. However, the embodiments of the present invention are not limited to the above, and it goes without saying that various modifications can be made and implemented within the scope not departing from the gist thereof other than the above.

[0069] For example, a line for treating 14 such as municipal water with the pretreatment apparatuses 13, the primary pretreatment apparatus 13A, and the secondary pretreatment apparatus 13B may be provided. If such a line is installed, it is possible to cope with a situation where, for example, in the event of heavy rain, the water quality of river water temporarily deteriorates and the boron concentration of municipal water or the like temporarily increases.

Explanation of Reference Numerals

[0070] 10 Pretreatment apparatus 11 Primary pure water apparatus 12 Secondary pure water apparatus 13 Pretreatment apparatus 13A Primary pretreatment apparatus 13B Secondary pretreatment apparatus 24 Vapor-liquid mixture 30 Measurement section 100 Ultrapure water production apparatus 200 Ultrapure water production apparatus 300 Ultrapure water production apparatus

Claims

1. Pretreatment for removing suspended substances in raw water containing soft drink water to obtain pretreated water, Primary treatment for removing total organic carbon components and ion components in the pretreated water to produce primary pure water, Secondary treatment for removing impurities in the primary pure water to produce ultrapure water, and having, An ultrapure water production method in which the boron concentration of the raw water is adjusted to be equal to or less than an allowable value calculated from the boron concentration required for the ultrapure water by changing the mixing ratio of soft drink water in the raw water or stopping the intake of soft drink water according to the time zone.

2. The ultrapure water production method according to claim 1, wherein when the boron concentration of the soft drink water or the raw water containing soft drink water exceeds the allowable value, a pretreatment for removing boron contained in the soft drink water or the raw water containing soft drink water is performed before the pretreatment.

3. The ultrapure water production method according to claim 2, wherein the pretreatment includes a primary pretreatment that is always performed and a secondary pretreatment that is performed when the boron concentration of the soft drink water or the raw water containing soft drink water exceeds a predetermined value.

4. A pretreatment device for removing suspended substances in raw water containing soft drink water to obtain pretreated water, A primary pure water device for removing total organic carbon components and ion components in the pretreated water to produce primary pure water, A secondary pure water device for removing impurities in the primary pure water to produce ultrapure water, A measurement unit for measuring the boron concentration of the soft drink water or the raw water containing soft drink water, and having, An ultrapure water production device in which the boron concentration of the raw water is adjusted to be equal to or less than an allowable value calculated from the boron concentration required for the ultrapure water by changing the mixing ratio of soft drink water in the raw water or stopping the intake of soft drink water according to the time zone.

5. The ultrapure water production device according to claim 4, further comprising a pretreatment device for removing boron from the soft drink water or the raw water containing soft drink water.

6. The ultrapure water production device according to claim 5, wherein the pretreatment device includes a primary pretreatment device that is always used and a secondary pretreatment device that is performed when the boron concentration of the soft drink water or the raw water containing soft drink water exceeds a predetermined value.

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