Ultrapure water production apparatus,method of producing ultrapure water,method of managing operation of the ultrapure water production apparatus,and method of measuring colloidal particles

Abstract

The ultrapure water production apparatus includes a secondary pure water device including: a water supply pump, an ion exchanger, and an ultrafiltration membrane device in order of the water supply pump, the ion exchanger, and the ultrafiltration membrane device, the secondary pure water device being configured to remove an impurity from primary pure water, in which at least one of a first combination of an acoustic particle counter and an optical particle counter or a second combination of the acoustic particle counter and a total organic carbon (TOC) meter is disposed at least one of an upstream side or a downstream side of the ultrafiltration membrane device

Description

Technical Field

[0001] The technology disclosed herein relates to ultrapure water manufacturing equipment, ultrapure water manufacturing methods, operation and management methods of ultrapure water manufacturing equipment, and methods for measuring colloidal particles. Prior Technology

[0002] Ultrapure water used in semiconductor manufacturing processes is produced by an ultrapure water production system that sequentially includes a primary pure water unit and a secondary pure water unit. In the ultrapure water production system, the primary pure water unit uses a reverse osmosis membrane or ion exchange device to remove total organic carbon (TOC) or ionic components from the raw water or pre-treated water to produce primary pure water. The secondary pure water unit removes trace amounts of impurities from the primary pure water to produce ultrapure water. Furthermore, an ultrafiltration (UF) membrane is typically installed at the end of the secondary pure water unit to remove nano-sized microparticles.

[0003] In this type of ultrapure water manufacturing apparatus, a microparticle meter for measuring the number of microparticles in the water is arranged downstream of the ultrafiltration membrane device, and the water quality is managed based on the measurement value of the microparticle meter (see, for example, International Publication No. 2015 / 064628). International Publication No. 2015 / 064628 discloses a structure in which a plurality of optical microparticle meters are arranged for the purpose of improving the measurement accuracy of microparticles. In addition, the ultrapure water manufacturing apparatus described in Japanese Patent No. 7563959 controls the flow rate of the water to be treated through the ion exchange device to efficiently remove microparticles.

[0004] (Patent Documents) (Patent Document 1) International Publication No. 2015 / 064628; (Patent Document 2) Japanese Patent No. 7563959. Summary of the Invention

[0005] (Problem to be Solved by the Invention) In semiconductor manufacturing processes, ultrapure water is used to clean semiconductor wafers. If impurities in the ultrapure water adhere to the semiconductor wafer, it can adversely affect the quality of the semiconductor. In recent years, with the significant progress in the miniaturization and hyper-integration of semiconductor circuits, the requirements for the quality of ultrapure water used in semiconductor manufacturing processes have become increasingly stringent.

[0006] Impurities adhering to semiconductor wafers include colloidal particles in addition to microparticles. A colloid refers to a state in which particles, much smaller than microparticles, are both dispersed and aggregated to some extent in a liquid, while also floating like clouds. Here, this aggregate of particles is called a colloidal particle.

[0007] In ultrapure water production equipment, various sources of colloidal particle generation can be considered, one of which is the ion exchange device. For example, unstable functional groups break off from the surface of the ion exchange resin, and the broken functional groups detach from the ion exchange resin and aggregate, or they aggregate on the surface of the ion exchange resin to become colloidal particles that will float in the water.

[0008] Colloidal particles, unlike ions, do not completely dissolve in liquids; they possess both the non-particle properties of ions and the particle properties of microparticles. Furthermore, colloidal particles can be considered to have smaller particle sizes compared to microparticles. Because colloidal particles are completely microparticles without a defined outer edge, their refractive index is extremely low compared to microparticles, making them difficult to measure using conventional optical microparticle meters.

[0009] However, colloidal particles, when attached to semiconductor wafers, can be confirmed using scanning electron microscopy (SEM) and their adverse effects on semiconductor quality can be determined. Therefore, it is desirable to measure colloidal particles during the production of ultrapure water to quantitatively understand the presence of colloidal particles in the treated water, or at least to understand their increase or decrease trends.

[0010] The technology disclosed herein provides an ultrapure water manufacturing apparatus, an ultrapure water manufacturing method, an operation and management method for the ultrapure water manufacturing apparatus, and a method for measuring colloidal particles.

[0011] (Means for solving the problem) The ultrapure water manufacturing apparatus related to the technology disclosed herein includes a secondary pure water unit, which sequentially includes a water pump, an ion exchange unit, and an ultrafiltration membrane unit, and is used to remove impurities from primary pure water; wherein, on the upstream side and / or downstream side of the ultrafiltration membrane unit, at least one of a first combination of an acoustic particle meter and an optical particle meter and a second combination of an acoustic particle meter and a TOC meter is arranged.

[0012] The ultrapure water manufacturing apparatus related to the technology disclosed in this paper may also have a processor for controlling the water recovery rate of the ultrafiltration membrane device.

[0013] The ultrapure water manufacturing method disclosed herein is an ultrapure water manufacturing method using the ultrapure water manufacturing apparatus described above.

[0014] The operation and management method of the ultrapure water manufacturing apparatus disclosed herein is an operation and management method of an ultrapure water manufacturing apparatus including a secondary pure water unit, which sequentially includes a water pump, an ion exchange unit, and an ultrafiltration membrane unit, and is used to remove impurities from primary pure water; wherein, at least one of a first combination of an acoustic particle meter and an optical particle meter and a second combination of an acoustic particle meter and a TOC meter disposed downstream of the ultrafiltration membrane unit is used, and operation and management are performed based on the measurement values ​​obtained from the combination.

[0015] The method for measuring colloidal particles disclosed herein is specifically for a secondary pure water device that sequentially includes a water pump, an ion exchange device, and an ultrafiltration membrane device to remove impurities from primary pure water. The colloidal particles are measured using at least one combination of an acoustic microparticle meter and an optical microparticle meter disposed downstream of the ultrafiltration membrane device, or a second combination of an acoustic microparticle meter and a TOC meter, based on measurement values ​​obtained from this combination.

[0016] (Effects of the Invention) Based on the technology related to this disclosure, an ultrapure water manufacturing apparatus, an ultrapure water manufacturing method, an operation and management method for the ultrapure water manufacturing apparatus, and a method for measuring colloidal particles can be provided. Simple Explanation of the Diagram

[0017] Figure 1 is a diagram showing the schematic structure of an ultrapure water production device. Figure 2 is a diagram showing the general structure of a secondary pure water device. Figure 3 is a schematic diagram that conceptually represents colloidal particles. Figure 4A is a schematic diagram that conceptually illustrates the principle of an optical microparticle meter. Figure 4B is a schematic diagram that conceptually illustrates the principle of an optical microparticle meter. Figure 5A is a schematic diagram that conceptually illustrates the principle of an acoustic microparticle meter. Figure 5B is a schematic diagram that conceptually illustrates the principle of an acoustic microparticle meter. Figure 6 is a graph showing the experimental results of the optical microparticle meter. Figure 7 is a graph showing the experimental results of the acoustic microparticle meter. Figure 8A is a graph comparing the characteristics of acoustic particle meters and optical particle meters. Figure 8B is a graph comparing the characteristics of acoustic particle meters and optical particle meters. Figure 9 is a diagram showing the combination of an acoustic particle meter and an optical particle meter. Figure 10A is a schematic diagram showing the capture state of microparticles or colloidal particles in a filter membrane. Figure 10B is a schematic diagram showing the capture state of microparticles or colloidal particles in a filter membrane. Figure 10C is a schematic diagram showing the capture state of microparticles or colloidal particles in a filter membrane. Figure 11 is a diagram illustrating an embodiment of changing the water recovery rate to remove colloidal particles. Figure 12 is a diagram showing the combination of an acoustic particle meter and a TOC meter. Figure 13A is a graph comparing the characteristics of an acoustic particle meter and a TOC meter. Figure 13B is a graph comparing the characteristics of an acoustic particle meter and a TOC meter. Implementation

[0018] The following describes embodiments of this disclosure. However, this disclosure is not limited to the following embodiments. In the case of embodiments described with reference to drawings in this disclosure, the structure of the embodiment is not limited to the structure shown in the drawings. Furthermore, the sizes of the components in each drawing are conceptual, and the relative sizes between components are not limited thereto. In the following drawing description, the same or similar symbols are used for the same part and similar parts. However, the drawings are stylized, and the relationship between thickness and planar dimensions, the thickness ratio of each device or component, etc., may differ from reality. Therefore, specific thicknesses and planar dimensions should be determined with reference to the following description. Furthermore, the drawings also include parts with different dimensional relationships or ratios. Moreover, unless specifically stated in the specification, the number of each constituent element in this disclosure is not limited to one, and there may be multiple elements. In the following embodiments, the constituent elements (including element steps, etc.) are not essential unless specifically stated otherwise. Similarly, numerical values ​​and their ranges are not limited to this disclosure. In this disclosure, the numerical range indicated by "~" includes the numerical values ​​before and after "~", and are respectively used as the minimum and maximum values. In the numerical ranges described in this disclosure, the upper or lower limit of a numerical range can be replaced by the upper or lower limit of other numerical ranges described in different stages. Furthermore, the upper or lower limit of the numerical ranges described in this disclosure can also be replaced by the values ​​shown in the embodiments. In this disclosure, when components are included, each component may contain a plurality of corresponding substances. When a plurality of substances corresponding to each component are present in the composition, the content rate or amount of each component, unless otherwise stated, refers to the total content rate or amount of the plurality of substances present in the composition. In this disclosure, particles corresponding to each component may also include a plurality of particles. When a plurality of particles corresponding to each component are present in the composition, the particle size of each component, unless otherwise stated, refers to the value for the mixture of the plurality of particles present in the composition. In this disclosure, the terms "layer" or "film" are used not only to describe the entirety of the region in which the layer or film is formed, but also to describe the portion of the region in which it is formed.

[0019] (Ultrapure Water Manufacturing Apparatus) Hereinafter, an ultrapure water manufacturing apparatus related to the technology disclosed herein will be described. As shown in FIG1, the ultrapure water manufacturing apparatus 10 related to this embodiment includes a pretreatment unit 11, a primary pure water unit 12, and a secondary pure water unit 13. The ultrapure water produced by the ultrapure water manufacturing apparatus 10 is sent to a point of use (POU) 14 and used there. The point of use 14 is, for example, a semiconductor manufacturing apparatus, and the ultrapure water is used in the semiconductor manufacturing process to clean semiconductor wafers.

[0020] The ultrapure water sent to point 14 is returned to the secondary pure water unit 13 via the circulation line LC. Although only one point 14 is shown in Figure 1, the ultrapure water production unit 10 can supply ultrapure water to two or more points 14. Furthermore, the used ultrapure water after being used at point 14 is returned to the pretreatment unit 11 via the recovery line LR. The circulation line LC and the recovery line LR are pipelines for liquid flow, constructed from piping, etc.

[0021] (Pretreatment Unit) Raw water is supplied to pretreatment unit 11. Pretreatment unit 11 includes a coagulation sedimentation unit, a sand filtration unit, a membrane filtration unit, etc., which remove turbidity from the raw water to produce pretreated water with suspended solids and some organic matter removed. Industrial water, tap water, groundwater, river water, etc. can be used as raw water. In addition, if a urea removal unit consisting of a combination of a high-pressure reverse osmosis membrane unit and a hypobromic acid addition and ultraviolet irradiation unit, or a boron removal unit consisting of a high-pressure reverse osmosis membrane unit and a boron selective ion exchange unit, is added to pretreatment unit 11, brackish water or sewage can also be used as raw water. One of these can be used as raw water, or two or more can be used in combination.

[0022] (Primary Pure Water Unit) The primary pure water unit 12 is used to perform primary pure water treatment, converting raw water into primary pure water. The primary pure water unit 12 is used to purify raw water, removing impurities to produce primary pure water. Specifically, the primary pure water unit 12 includes a desalination unit for removing impurity ions; a reverse osmosis membrane unit for removing inorganic ions, organic matter, microparticles, etc.; a vacuum degassing unit or membrane degassing unit for removing dissolved oxygen, etc.; and various other units such as a regenerative mixed-bed desalination unit and an electro-deionization unit for removing residual ions. It should be noted that it can also replace raw water and perform primary pure water treatment on pretreated water.

[0023] (Secondary Pure Water Unit) The secondary pure water unit 13 is a device used to perform secondary pure water treatment to remove trace amounts of impurities from primary pure water in order to produce ultrapure water.

[0024] As shown in Figure 2, the secondary pure water unit 13 sequentially includes a pure water tank (TK) 21, a water pump P1 located downstream of the pure water tank 21, an ultraviolet irradiation device (UV) 22, a membrane degassing device (MDG) 23, a non-regenerative mixed-bed ion exchange resin device (Polisher) 24, a booster pump P2, and an ultrafiltration membrane device (UF) 25. In the secondary pure water unit 13, the primary pure water stored in the pure water tank 21 is supplied sequentially to each device from the ultraviolet irradiation device 22 to the ultrafiltration membrane device 25 via the water pump P1 and the booster pump P2, where it is treated to produce ultrapure water. It should be noted that the booster pump P2 can also be located upstream of the non-regenerative mixed-bed ion exchange resin device 24.

[0025] The pure water tank 21 is not particularly limited in terms of material or shape, as long as it does not rust, has almost no leaching components from the container, and can stably store pure water. The material of the pure water tank 21 is preferably fiber-reinforced plastic (FRP), polyethylene, SUS304, or lined with fluoropolymers such as Teflon™.

[0026] (Ultraviolet Irradiation Device) In the ultraviolet irradiation device 22, ultraviolet light is used to irradiate primary pure water to decompose organic matter or kill live bacteria (i.e., sterilize). The ultraviolet irradiation device 22 is equipped with an ultraviolet lamp that can irradiate with a wavelength around 185nm or around 254nm to reliably decompose organic matter or sterilize primary pure water. There are no particular limitations on the ultraviolet lamp used in the ultraviolet irradiation device 22, but low-pressure mercury lamps are better in terms of ease of handling. Furthermore, examples of ultraviolet irradiation devices 22 include a flow-through type where the ultraviolet lamp is arranged inside the housing along the flow path of the water to be treated, or an immersion type where the ultraviolet lamp is immersed in a tank containing the water to be treated. From the viewpoint of treatment efficiency, the flow-through type is preferred.

[0027] (Membrane Degassing Unit) The membrane degassing unit 23 uses a gas separation membrane that allows gas to pass through but not water to remove gas, especially dissolved oxygen, from primary pure water.

[0028] (Non-regenerative mixed-bed ion exchange resin device) Primary purified water, after having its dissolved oxygen concentration removed by membrane degassing device 23, is sent to non-regenerative mixed-bed ion exchange resin device 24. Non-regenerative mixed-bed ion exchange resin device 24 adsorbs and removes impurities such as organic acids produced by the decomposition of organic matter by ultraviolet irradiation device 22, or residual metal ions in the water. Non-regenerative mixed-bed ion exchange resin device 24 is, for example, a structure in which a mixed-bed ion exchange resin is filled in a cylindrical, sealed container. Mixed-bed ion exchange resin is typically a mixture of cation exchange resin and anion exchange resin. Non-regenerative mixed-bed ion exchange resin device 24 is an example of an "ion exchange device" as disclosed in this specification.

[0029] (Booster Pump) Booster pump P2 is a pump that applies pressure to increase the water pressure. Booster pump P2 ensures that the water pressure at the outlet of the ultrafiltration membrane device 25 is properly maintained at the water pressure required at the point of use 14.

[0030] (Ultrafiltration Membrane Device) The ultrafiltration membrane device 25 includes one or more ultrafiltration membrane modules, or one or more ultrafiltration membrane cartridges. An ultrafiltration membrane module is formed by placing an ultrafiltration membrane inside a housing having a water inlet, a permeate outlet, and a concentrate outlet. Its structure connects each opening of the module to piping, allowing the treated water to pass through the ultrafiltration membrane. The ultrafiltration membrane module has the advantage that when the ultrafiltration membrane becomes clogged and its filtration performance deteriorates, the entire module can be replaced, and deteriorated ultrafiltration membranes can be cleaned module by module. The ultrafiltration membrane installed in the ultrafiltration membrane module is sometimes also called an ultrafiltration membrane cartridge. In the case of an ultrafiltration membrane cartridge, only the cartridge within the ultrafiltration membrane module can be replaced. The ultrafiltration membrane is, for example, made of hollow fiber membrane.

[0031] The ultrafiltration membrane device 25 is used to remove microparticles from water, such as microparticles with a diameter of 50 nm or larger, preferably 10 nm or larger. The ultrafiltration membrane device consists of one or more ultrafiltration membrane modules. The type of ultrafiltration membrane in the ultrafiltration membrane module is not particularly limited; it is usually a hollow fiber membrane, but can also be a spiral membrane, tubular membrane, flat membrane, etc. The material of the ultrafiltration membrane is polyvinylidene fluoride, polyvinylidene fluoride, polyethylene, polypropylene, etc., with a nominal molecular weight cutoff preferably of 3000-8000, more preferably 4000-6000. The ultrafiltration membrane module can be either internal pressure or external pressure type. Furthermore, the ultrafiltration membrane device 25 can be a crossflow type or a total filtration type. Additionally, the ultrafiltration membrane device 25 can also be multiple sections connected in series.

[0032] In the ultrafiltration membrane device 25, the inlet is connected to the water supply line on the booster pump P2 side, the outlet on the permeate side is connected to the circulation line LC, and the outlet on the concentration side is connected to the drain line LB. A valve VA is installed along the path of the circulation line LC. Furthermore, the circulation line LC branches upstream of the valve VA, and the branched water supply line LA is connected to the point of use 14. Ultrapure water not used at the point of use 14 is returned to the pure water tank 21.

[0033] Downstream of the ultrafiltration membrane device 25, a measuring device 31 for measuring impurities in the treated water is installed in the pipeline. As an example, the measuring device 31 comprises an acoustic particle meter 31A, an optical particle meter 31B, and a TOC meter 31C. The measured values ​​from the measuring device 31 are output to the processor 26. The processor 26 manages the water quality based on the measured values.

[0034] Although impurities are removed from the treated water in the ultrafiltration membrane device 25, they cannot be completely removed even by the ultrafiltration membrane device 25. The processor 26 monitors whether the amount of impurities in the treated water is within a preset allowable range based on the measurement value obtained from the measuring device 31. Furthermore, the processor 26 repeatedly removes impurities using the ultrafiltration membrane device 25, etc., until the measurement value is within the allowable range. When the measurement value drops to within the allowable range, the produced ultrapure water is sent to the point of use 14. That is, downstream of the measuring device 31, before branching to the water supply line LA, a bypass line LD is connected to return to the pure water tank 21. Furthermore, the destination of the treated water passing through the ultrafiltration membrane device 25 can be switched to the bypass line LD or the water supply line LA by means of a valve not shown in the figure. If the water quality is outside the permissible range, the bypass line LD returning to the pure water tank 21 is used to directly send the treated water from the ultrafiltration membrane device 25 back to the pure water tank 21. When the measured value is within the permissible range, the supply line LA to the point of use 14 is switched. Impurities include not only microparticles, but also dissolved organic carbon (DOC), colloidal particles, metals such as iron, copper, and calcium, and boron, which are dissolved in the treated water.

[0035] The acoustic particle meter 31A transmits acoustic waves containing the inherent energy of the target particles into the treated water, and uses a piezoelectric element to detect the cavitation pressure caused by the received acoustic waves. Furthermore, when a certain pressure is detected, the particles are counted, and the number of counted particles is output as a measurement value to the processor 26. For example, the acoustic particle meter 31A uses the "NanoPULSTM" manufactured by OVIVO Corporation.

[0036] The optical particle meter 31B emits laser light into the water being treated and uses a focusing optical system to concentrate the scattered light scattered by the laser light irradiating the particles. A photoelectric conversion element then detects the concentrated light. Furthermore, it counts the number of particles based on the detected amount of light received and outputs the counted particle number as a measurement value to the processor 26. For example, the optical particle meter 31B uses the "Ultra DITM 20Plus" manufactured by PMS Corporation.

[0037] The TOC meter 31C is a device used to measure the total organic carbon (TOC) contained in organic matter present in treated water. In addition to dissolved organic carbon (DOC), the total carbon also includes a small proportion of particulate or colloidal organic carbon (i.e., the amount of organic carbon insoluble in the treated water). As is well known, the TOC meter 31C uses ultraviolet light or an oxidant to decompose the organic matter in the treated water, and measures the amount of carbon dioxide (CO2) produced using methods such as infrared absorption or conductivity methods. The amount of carbon dioxide produced is proportional to the total carbon content of the organic matter; therefore, by measuring the amount of carbon dioxide produced, the total carbon content of the treated water can be quantitatively determined. The TOC meter 31C outputs the measured total carbon content as a measurement value. The TOC meter 31C used here can be any ultrapure water TOC meter, such as the Anatel A1000-XP manufactured by Beckman Coulter, the Accura SXII manufactured by T&C Technical Co., Ltd., the Sievers M500e, Sievers 500RL, Sievers 900 manufactured by Suez, or the 6000TOC manufactured by Mettler Toledo, without any particular restrictions.

[0038] Furthermore, the processor 26 can measure colloidal particles, which are impurities in the water being treated, based on two measurement values: the acoustic particle meter 31A and the optical particle meter 31B.

[0039] Figure 3 is a schematic diagram conceptually representing colloidal particles CL. The ion exchange resin RE schematically represents the cation exchange resin and anion exchange resin disposed in a non-regenerating mixed-bed ion exchange resin device 24. From the surface of the ion exchange resin RE, ions IO, derived from the functional groups of the ion exchange resin, may sometimes detach. If these ions IO aggregate in the liquid, they may become colloidal particles CL. It should be noted that while colloidal particles CL may form in water after ions IO detach from the ion exchange resin RE, they may also form on the ion exchange resin RE or in the water-contact portion within the secondary pure water device 13, such as on the filter membrane of the ultrafiltration membrane device 25, or on the surface of piping, etc. Here, colloidal particles CL include monomers, dimers, trimers, and polymers. The particle size of colloidal particles CL is considered to be in the range of approximately several nanometers to tens of nanometers or smaller, including those comparable in size to microparticles MP. As mentioned above, colloidal particles (CL) do not completely dissolve in liquids like ions (IO). They possess both the non-particle properties of ions (IO) and the particle properties of microparticles (MP).

[0040] In view of the properties of colloidal particles CL, the inventors discovered that colloidal particles can be measured based on the measurements of an optical particle meter 31B and an acoustic particle meter 31A. That is, through hypothetical experiments, the inventors discovered that the acoustic particle meter 31A can detect colloidal particles CL in addition to microparticles MP, and that by combining the optical particle meter 31B and the acoustic particle meter 31A, colloidal particles CL can be quantitatively measured.

[0041] Figure 4 is a conceptual diagram illustrating the reason why the detection of colloidal particles CL is difficult in the optical particle meter 31B. As shown in Figure 4A, in the optical particle meter 31B, laser light DL is irradiated onto microparticles MP, and the microparticles MP are detected by detecting the scattered light SL scattered by the microparticles MP. However, colloidal particles CL exhibit strong non-particle properties optically, with a very small refractive index compared to microparticles MP. Therefore, as shown in Figure 4B, even when laser light DL is irradiated onto colloidal particles CL, scattering is not easily generated. This is considered the reason why the optical particle meter 31B can detect microparticles MP but cannot detect colloidal particles CL.

[0042] On the other hand, Figure 5 is a conceptual diagram illustrating the reason why the detection of colloidal particles CL is possible in the acoustic particle meter 31A. As shown in Figure 5A, in the acoustic particle meter 31A, a sound wave SW is irradiated onto microparticles MP, and the pressure of the liquid cavitation CV generated by the vibration of the microparticles MP that have received the sound wave SW is detected. Colloidal particles CL are insoluble in the liquid and, like microparticles MP, have an outer edge and exist as a solid. Therefore, as shown in Figure 5B, if colloidal particles CL are irradiated with a sound wave SW, they will also vibrate like microparticles MP, generating cavitation CV in the liquid. By detecting the pressure based on this cavitation CV, the acoustic particle meter 31A is believed to also be able to detect colloidal particles CL.

[0043] Figures 6 and 7 show the experimental results verifying the above hypothesis. The experiment was conducted by adding gold colloidal standard particles and PSL (polystyrene latex) standard microparticles online to ultrapure water, and measuring the amount of microparticles using a microparticle meter installed downstream of the ultrafiltration membrane device 25. It should be noted that the gold colloidal standard particles used were standard gold colloids manufactured by BBI Solutions, and the PSL standard microparticles were standard latex particles manufactured by Thermo Fisher. The gold colloidal standard particles are a model of microparticles (MP), and the PSL standard microparticles are a model of colloidal particles. In the following, the gold colloidal standard particles will be referred to as gold colloidal particles and denoted by AU in the figures. The PSL standard microparticles will be referred to as latex spheres and denoted by PSL in the figures. The above-mentioned products were used as the acoustic microparticle meter 31A and the optical microparticle meter 31B.

[0044] Figure 6 is a graph showing the experimental results of detecting colloidal gold particles (Au) as the microparticle MP model and latex spheres (PSL) as the colloidal particle CL model using the optical microparticle meter 31B. Figure 7 is a graph showing the experimental results of detecting colloidal gold particles (Au) and latex spheres (PSL) using the acoustic microparticle meter 31A. In Figures 6 and 7, the horizontal axis represents the particle diameter (nm), and the vertical axis represents the detection rate. Although there is no data in Figures 6 and 7 with a particle diameter less than 20nm, this is because the detection limit of the acoustic microparticle meter 31A and the optical microparticle meter 31B is 20nm. The aforementioned products were used as the acoustic microparticle meter 31A and the optical microparticle meter 31B.

[0045] Latex spheres (PSL) are organic materials, and it is hypothesized that the finer the particle size, the greater the colloidal properties. On the other hand, it is hypothesized that this tendency is less likely to occur with gold colloidal particles (Au) as they exhibit metallic properties. As shown in Figure 6, in the optical microparticle meter 31B, there is a discrepancy between the detection rates of gold colloidal particles (Au) and latex spheres (PSL), indicating that the detection rate of latex spheres (PSL) is lower than that of gold colloidal particles (Au). Since the difference widens as the particle size increases, it can be concluded that in the optical microparticle meter 31B, the stronger the non-particle properties, the more difficult the detection. This experimental result, as shown in Figure 4, shows that for colloidal particles CL, whose refractive index is lower than that of microparticles MP, scattered light SL is not easily generated, thus conforming to the hypothesis of difficult detection.

[0046] On the other hand, as shown in Figure 7, in the acoustic microparticle meter 31A, the detection rates of gold colloidal particles (Au) and latex spheres (PSL) show no discrepancy, indicating that latex spheres (PSL) can be detected to the same extent as gold colloidal particles (Au). This experimental result, as shown in Figure 5, shows that colloidal particles CL exhibit particle properties in acoustic wave characteristics, consistent with the hypothesis that they generate cavitation erosion CV upon receiving acoustic waves SW.

[0047] These details are summarized in Figure 8. Specifically, as shown in Figure 8A, in the acoustic particle meter 31A, both MP particles and CL colloidal particles can be detected. In contrast, in the optical particle meter 31B, while MP particles can be detected, CL colloidal particles cannot. Therefore, as shown in Figure 8B, the measurement value Xa of the acoustic particle meter 31A includes both the measurement values ​​of MP particles and CL colloidal particles. Conversely, the measurement value Xb of the optical particle meter 31B does not include the measurement value of CL colloidal particles, only the measurement value of MP particles.

[0048] Therefore, as shown in Figure 9, in the processor 26, the measured value X_CL of colloidal particles CL can be obtained by subtracting the measured value Xb of optical particle meter 31B from the measured value Xa of acoustic particle meter 31A. The measured value X_CL, like Xa and Xb, represents the number of colloidal particles CL per unit volume. In this way, the processor 26 can quantitatively determine the number of colloidal particles CL.

[0049] Next, the method for removing the measured colloidal particles CL will be explained. Since colloidal particles CL are mostly smaller than microparticles MP, they are currently considered difficult to remove even using ultrafiltration membrane devices 25. Furthermore, although attempts have been made to capture and remove colloidal particles CL using electrical methods, considering that they are aggregates of ions IO, the low concentration of colloidal particles CL results in a low probability of contact between ions IO and the substance capturing ions IO, making capture difficult even with electrical methods.

[0050] Therefore, the inventors discovered a method for removing colloidal particles CL from treated water by controlling the operating conditions of the ultrafiltration membrane device 25. Specifically, this method, as an operation management method for the ultrapure water production apparatus 10, includes setting the operating conditions of the ultrafiltration membrane device 25 to operate when the water recovery rate is less than 80%. By means of this method, as explained below, it is possible to suppress colloidal particles CL smaller than the pore size of the ultrafiltration membrane from passing through the ultrafiltration membrane. The water recovery rate is controlled by the processor 26 controlling the opening of valves VA and VB, and controlling the driving conditions of the water pump P1 or the booster pump P2, etc. The "water recovery rate" is defined as "the flow rate of the treated water from the ultrafiltration membrane device / the flow rate of the treated water supplied to the ultrafiltration membrane device".

[0051] Firstly, conventional ultrafiltration membrane devices are considered to capture microparticles (MP) larger than the pore size of the ultrafiltration membrane and remove them from water; that is, filtration is mainly carried out through surface filtration mechanisms. However, since most colloidal particles (CL) observed in the final ultrapure water are smaller than the pore size of the ultrafiltration membrane, it is assumed that colloidal particles (CL) cannot be removed by the aforementioned surface filtration. Based on our examination, we hypothesized that colloidal particles (CL) are removed through a depth filtration mechanism rather than surface filtration, and conducted experiments. The results showed that by filtration under cross-flow conditions and with the aforementioned water recovery rate, colloidal particles (CL) can be removed by the ultrafiltration membrane device 25. The reasoning may not be clear, but it is believed to be as follows.

[0052] Figure 10 illustrates the capture state of microparticles (MP) and colloidal particles (CL) on the membrane during membrane filtration in this embodiment. From top to bottom, Figure 10(A) shows the initial stage of filtration, Figure 10(B) shows the filtration process (in other words, the middle stage), and Figure 10(C) shows the filtration process further (in other words, the final stage).

[0053] In Figure 10, rectangles represent the membrane surface 41 and the inner wall of the pores 42 of the filter membrane, and solid circles represent microparticles (MP). Dashed circles represent colloidal particles (CL). Furthermore, thick arrows represent water flow, and thin arrows represent the movement of microparticles (MP).

[0054] First, the mechanism of MP particle capture in the filter membrane will be explained. The sites of MP particle capture and adsorption can be considered as the membrane surface 41 and the inner wall of the pores 42. When the filter membrane is new or nearly new, the number of MP particles already adsorbed on the membrane surface 41 or the inner wall of the pores 42 is small. Therefore, either the membrane surface 41 or the inner wall of the pores 42 can adsorb MP particles. Since the water being treated first contacts the membrane surface 41, as shown in Figure 10A, MP particles are mainly adsorbed on the membrane surface 41. Subsequently, as MP particles adsorbed on the membrane surface 41 continue to be adsorbed, as shown in Figure 10B, MP particles will gradually be adsorbed on the inner wall of the pores 42.

[0055] Furthermore, as membrane filtration proceeds, the amount of MP particles adsorbed on the membrane surface 41 or the inner wall of the pores 42 increases as the microparticles adsorb onto the membrane. Consequently, new MP particles become difficult to adsorb onto the membrane, and as shown in Figure 10C, they will permeate through the membrane. This results in a decrease in the removal rate of MP particles.

[0056] Here, during membrane filtration, the microparticles (MP) repeatedly adsorb onto and desorb from the membrane surface 41 of the ultrafiltration membrane. Therefore, by setting the membrane filtration to crossflow and increasing the flow rate along the membrane surface 41, the increase in the concentration of microparticles (MP) on the membrane surface 41 is suppressed, thus maintaining the initial state as shown in Figure 10A. This is believed to suppress the passage of microparticles (MP) smaller than the pore size of the ultrafiltration membrane through the pores, thereby maintaining a high removal rate.

[0057] The behavior of colloidal particles CL is similar to that of microparticles MP, which have a smaller pore size than the ultrafiltration membrane. It is believed that during membrane filtration, they repeatedly adsorb onto and desorb from the membrane surface 41. Therefore, by suppressing the increase in the concentration of colloidal particles CL attached to the membrane surface 41, it is possible to suppress the passage of colloidal particles CL, which have a smaller pore size than the ultrafiltration membrane, through the pores of the ultrafiltration membrane. As a result, it is believed that colloidal particles CL can be removed.

[0058] Furthermore, as an example, the method for maintaining the initial state shown in Figure 10A is to operate the system with the water recovery rate set to less than 80%. Normally, the water recovery rate is set to 80% or higher, but by intentionally reducing the water recovery rate to less than 80%, i.e., increasing the flow rate on the concentration side, the flow rate along the membrane surface 41 can be increased. This reduces the amount of microparticles (MP) or colloidal particles (CL) deposited on the membrane surface 41, thus maintaining the initial state shown in Figure 10A.

[0059] Figure 11 shows an example of the method of using the ultrapure water production apparatus 10, which is the measuring device 31 of the above embodiment, and the experimental results of attempting to remove colloidal particles (CL) by controlling the water recovery rate. The water recovery rate of the ultrafiltration membrane device 25 in Example 1 was 55% under operating condition 1, and the water recovery rate in Example 2 was 85% under operating condition 2. The pressure difference between the permeate side and the concentration side of the filter membrane was 1 kgf / cm². Furthermore, the filter membrane used was Microza® OAT6036 (molecular weight cutoff 6000) manufactured by Asahi Kasei Corporation. In addition, the mixed-bed ion exchange resin used in the non-regenerative mixed-bed ion exchange resin device 24 was "N-Lite® MBSP" manufactured by Nomura Micro Science, and the space velocity (SV) was set to 40 (1 / h). In the experiment, firstly, the water recovery rate of the ultrafiltration membrane device 25 was set to 85%, and the secondary pure water device 13 was operated and data was measured. Then, the water recovery rate was set to 55%, and the secondary pure water device 13 was run for thirty days. After the data stabilized, measurements were taken to obtain the results. The secondary pure water device 13 used in the experiment had the same structure as the one shown in Figure 2, except that it did not have the ultraviolet irradiation device 22 and the membrane degassing device 23.

[0060] In Example 1, the measurement value of the acoustic particle meter 31A is Xa1, and the measurement value of the optical particle meter 31B is Xb1, with a difference of ΔX1, which represents the number of colloidal particles CL per unit volume in Example 1. In Example 2, the measurement value of the acoustic particle meter 31A is Xa2, and the measurement value of the optical particle meter 31B is Xb2, with a difference of ΔX2, which represents the number of colloidal particles CL per unit volume in the comparative example. More specific values ​​are shown in Table 1 below.

[0061] Acoustic type (units / L) Optical type (pieces / L) Colloidal particles (Xa-Xb) Example 1 Xa1 256 Xb1 240 ΔX1 16 Example 2 Xa2 650 Xb2 432 ΔX2 218 [Table 1]

[0062] As shown in Table 1, the amount of colloidal particles CL in Example 1 (i.e., ΔX1) was reduced to less than 1 / 10 compared to ΔX2 in Example 2.

[0063] It was verified that setting the water recovery rate to less than 80%, as in Example 1, could remove colloidal particles CL.

[0064] It should be noted that although the water recovery rate is set to be less than 80%, if it is less than 50%, the practicality will decrease due to the low water recovery rate. From the viewpoint of improving the removal rate of colloidal particles (CL) and efficiently obtaining ultrapure water, the water recovery rate in the ultrafiltration membrane device 25 is preferably 50% or more but less than 80%.

[0065] As explained above, the ultrapure water manufacturing apparatus 10 disclosed herein sequentially includes a water pump P1 (an example of a water pump), a non-regenerative mixed-bed ion exchange resin device 24 (an example of an ion exchange device), and an ultrafiltration membrane device 25. It also includes a secondary pure water device 13 for removing impurities from primary pure water. Downstream of the ultrafiltration membrane device 25, a combination of an acoustic particle meter 31A and an optical particle meter 31B (this combination corresponds to the first combination) is arranged. This ultrapure water manufacturing apparatus 10 can be used in methods for measuring colloidal particles (CL). The ultrapure water manufacturing apparatus 10 will be used in the ultrapure water manufacturing method disclosed herein.

[0066] As a water pump, there may be only a water pump P1, or a booster pump P2 may be provided as in the above embodiment.

[0067] Furthermore, the ultrapure water manufacturing apparatus 10 related to the technology disclosed herein, having a combination of an acoustic microparticle meter 31A and an optical microparticle meter 31B, can quantitatively measure the colloidal particles CL in the water being treated, as illustrated in Figures 8 and 9.

[0068] Furthermore, the ultrapure water manufacturing apparatus 10 disclosed herein includes a processor 26 for controlling the water recovery rate of the ultrafiltration membrane device 25. Therefore, as shown in Figures 10 and 11, colloidal particles CL contained in the ultrapure water can be removed by controlling the water recovery rate.

[0069] In this embodiment, although the acoustic particle meter 31A and the optical particle meter 31B were compared using the same detection limit, the detection limits do not necessarily need to be the same. When the detection limits are different, although it is impossible to take the difference between the measurement values ​​of the acoustic particle meter 31A and the optical particle meter 31B, the increase or decrease trend of colloidal particles CL can be grasped from the trends of the two measurement values. Furthermore, the amount of colloidal particles CL can be estimated in advance using a conversion factor between the measurement values ​​of the acoustic particle meter 31A and the optical particle meter 31B. For example, if latex balls (PSL) of various particle sizes are used, the same trend as in Figure 6 can be determined in advance for each particle size, and using this trend, a conversion method such as a conversion factor can be used to determine the amount of colloidal particles CL even when the detection limits are different.

[0070] (Modification) The modification shown in Figure 12 is a combination of measuring instruments used to measure colloidal particles CL, and it differs from the combination shown in Figure 9 of the above-described embodiment. Since the other structures are the same as in the above-described embodiment, only the differences will be described below.

[0071] This variation is based on the assumption that the TOC meter 31C can be used to measure the amount of colloidal particles CL. That is, although the TOC meter 31C is a measuring instrument for the total carbon content of organic matter in water, since colloidal particles CL include organic matter, the measured value of the TOC meter 31C should at least partially correspond to the amount of colloidal particles CL. Furthermore, it can be assumed that in ultrapure water, there are not colloidal particles composed of individual elements such as silica colloids, ferrocolloids, or organic colloids, but rather colloidal particles CL composed of multiple elements; moreover, the composition ratio in colloidal particles CL does not vary with the individual colloidal particles CL, but remains approximately constant. Thus, it is assumed that there should be some relationship between the value of the TOC meter 31C and the amount of colloidal particles CL obtained by the method of the above-described embodiment (i.e., ΔX = Xa - Xb). This variation is an insight discovered under this assumption.

[0072] In the above embodiments, although the colloidal particles CL are measured based on the measurement values ​​of the acoustic particle meter 31A and the optical particle meter 31B, in the modified example shown in FIG12, a combination of the acoustic particle meter 31A and the TOC meter 31C (this combination is equivalent to the second combination) is used, and the colloidal particles CL are measured based on two measurement values: the measurement value of the acoustic particle meter 31A and the measurement value of the TOC meter 31C. However, in the case of the modified example, although it is difficult to quantify the colloidal particles CL, it is possible to measure the degree of increase or decrease of the colloidal particles CL.

[0073] As shown in Figure 13A, the acoustic particle meter 31A can detect both particulate particles (MP) and colloidal particles (CL), but it cannot detect dissolved organic carbon (DOC) in water. On the other hand, the TOC meter 31C can detect DOC. Furthermore, as mentioned above, the TOC meter 31C can detect particulate organic carbon (i.e., the amount of particulate organic carbon insoluble in the treated water) in addition to DOC. This particulate organic carbon accounts for a very small proportion of the total carbon (TOC), and most of it is considered to be colloidal particles (CL). Thus, the TOC meter 31C can also detect colloidal particles (CL).

[0074] Thus, as shown in Figure 13B, the measurement value Xa of the acoustic particle meter 31A contains microparticles (MP) and colloidal particles (CL), while the measurement value Xc of the TOC meter 31C contains DOC and colloidal particles (CL). The relationship between the amount of colloidal particles (CL) obtained from the difference between the measurement value Xa of the acoustic particle meter 31A and the measurement value Xb of the optical particle meter 31B (i.e., Xa-Xb) and Xc was examined, and the following relationship was found: That is, when Xc remains unchanged and only Xa increases or decreases, it is considered an increase or decrease in microparticles (MP). Furthermore, when Xa remains unchanged and only Xc increases or decreases, it is considered an increase or decrease in DOC. Moreover, when both Xa and Xc increase or decrease, it is considered highly likely that the colloidal particles (CL) are increasing or decreasing. The processor 26 can grasp the tendency of increase or decrease in colloidal particles (CL) based on the changes in Xa and Xc. Thus, in the technology disclosed in this paper, the concept of "measuring colloidal particles" includes not only quantitatively controlling the colloidal particle CL, but also controlling the increase or decrease trend of the colloidal particle CL.

[0075] At this point, quantitative control of colloidal particles (CL) is out of the question, and even understanding their tendency to increase or decrease is difficult. Therefore, even if quantitative control is not possible, understanding only the tendency of colloidal particles (CL) to increase or decrease has significant practical advantages.

[0076] Furthermore, for example, after reducing the amount of DOC to approximately a certain level, as shown in Figure 11, when operating the ultrafiltration membrane device 25 with a water recovery rate of 55%, if it can be confirmed that both the values ​​of Xa and Xc decrease, the probability of a decrease in colloidal particles CL is considered relatively high. In this case, the processor 26 can sometimes perform a predetermined calculation based on the two measurements of Xa and Xc to quantitatively determine the amount of colloidal particles CL.

[0077] It is important to note that the TOC meter 31C measures concentration in ppb. In contrast, the acoustic particle meter 31A measures the number of particles per unit volume in particles / L. Therefore, unlike the combination of the acoustic and optical particle meters 31A, it is not possible to quantify the colloidal particles CL simply by taking the difference between the acoustic measurement Xa and the optical measurement Xb. However, by using a formula that incorporates the TOC meter measurement (i.e., Xc) and a coefficient to convert concentration to number, the approximate amount of colloidal particles CL can be estimated.

[0078] In a modified example, a method can be applied to remove colloidal particles CL by setting the water recovery rate of the ultrafiltration membrane device 25 to less than 80%.

[0079] The experimental results for the modified examples are shown in Table 2 below. Example 1 in Table 2 was obtained by measuring TOC using a TOC meter 31C at the same time as in Example 1 of Table 1. Similarly, Example 2 was obtained by measuring TOC using a TOC meter 31C at the same time as in Example 2 of Table 2. It should be noted that a Sievers M500e manufactured by Suez Corporation was used as the TOC meter.

[0080] Acoustic type (units / L) TOC (ppb) Colloidal particles (Xa-Xb) Example 1 Xa1 256 Xc1 0.14 ΔX1 16 Example 2 Xa2 650 Xc2 0.4 ΔX2 218 Increase / decrease rate (%) -61 -65 [Table 2]

[0081] In Table 2, comparing Examples 1 and 2, the differences (ΔX1 and ΔX2) between the measured values ​​(Xa) of the acoustic particle meter 31A and the measured values ​​(Xb) of the optical particle meter 31B show that the colloidal particles CL decrease in Example 1. However, the measured value Xa1 of Example 1 is less than the measured value Xa2 of Example 2, and the measured value Xc1 of Example 1 is also less than the measured value Xc2 of Example 2. Since both Xa and Xc decrease in this way, it can be judged from this trend that the colloidal particles CL are decreasing.

[0082] Furthermore, Table 3 comparing Example 2 and another Example 3 is shown below. In Table 3, Example 2 is the same as in Table 2. Example 3 is the same as in Example 2 except that the SV of the non-regenerative mixed-bed ion exchange resin device 24 is changed from 24 (1 / h) to 200 (1 / h) under the conditions of Example 2. Example 3 is a case in which the TOC is reduced by increasing the SV.

[0083] Acoustic type (units / L) TOC (ppb) Colloidal particles (Xa-Xb) Example 3 Xa3 750 Xc3 0.22 ΔX3 220 Example 2 Xa2 650 Xc2 0.4 ΔX2 218 Increase / decrease rate (%) 15 -45 [Table 3]

[0084] Comparing Examples 2 and 3, the colloidal particle CL remained largely unchanged. Furthermore, the measured values ​​Xa2 and Xa3 of the acoustic microparticle meter 31A were also approximately the same. In contrast, comparing the measured values ​​Xc2 and Xc3 of the TOC meter 31C, Xc3 decreased relative to Xc2. Therefore, Table 3 corresponds to the case where Xa remained unchanged, but Xc decreased. In this case, based on the relationship between the increases and decreases of Xa and Xc, it can be determined that the decrease in TOC was due to a decrease in DOC.

[0085] Thus, as shown in Tables 2 and 3, it can be seen that the amount of colloidal particles CL (i.e., Xa-Xb), obtained from the difference between the measurement value Xa of the acoustic particle meter 31A and the measurement value Xb of the optical particle meter 31B, is correlated with the combination of the measurement value Xa of the acoustic particle meter 31A and the measurement value Xc of the TOC meter 31C. Therefore, by using the combination of the acoustic particle meter 31A and the TOC meter 31C, at least the tendency of increase or decrease in colloidal particles CL can be grasped.

[0086] It should be noted that in Modification 1, when using an optical particle meter 31B instead of an acoustic particle meter 31A, the same results as in Modification 1 cannot be obtained; no clear relationship was found between the amount of colloidal particles CL (i.e., Xa-Xb) and the measured value Xc of the TOC meter 31C. Therefore, when measuring colloidal particles CL using the present invention, the acoustic particle meter 31A is necessary; in order to supplement this measuring device, the use of an optical particle meter 31B or a TOC meter 31C is confirmed to be effective.

[0087] Thus, the ultrapure water manufacturing apparatus 10 related to the modification of the technology disclosed herein has a combination of an acoustic particle meter 31A and a TOC meter 31C (this combination is equivalent to the second combination). The TOC meter 31C is an essential measuring instrument in the field of ultrapure water manufacturing and has been widely used to date. Therefore, according to the modification, the TOC meter 31C, which has been used to date, can be effectively utilized for measuring colloidal particles CL. It should be noted that, in the modification, the optical particle meter 31B can of course be omitted.

[0088] Furthermore, the measuring devices 31 of the first or second combination included in the ultrapure water production apparatus 10, which are related to the technology disclosed in this book, can be used not only for measuring colloidal particles (CL) but also for the operation and management of the ultrapure water production apparatus 10. That is, if the measuring device 31 indicates a high probability of a change in the amount of colloidal particles (CL), the ultrapure water production apparatus 10 is considered to have a cause. For example, if the increase in the amount of colloidal particles (CL) is due to a change in operating conditions, restoring those operating conditions can improve water quality. Furthermore, if it can be determined that the problem is caused by a problem with a certain device, the problem can be addressed by eliminating that device. Moreover, if a change in the amount of colloidal particles (CL) is observed after changing the operating conditions of the ultrapure water production apparatus 10, the optimal operating conditions can be identified. Because this tendency can be achieved by using the first combination of acoustic particle meter 31A and optical particle meter 31B, or the second combination of acoustic particle meter 31A and TOC meter 31C, by monitoring changes in measured values ​​over time, the ultrapure water production device 10 can be made to perform this kind of operation management very easily.

[0089] In the case of the first combination of the acoustic particle meter 31A and the optical particle meter 31B in the above embodiment, or the second combination of the acoustic particle meter 31A and the TOC meter 31C in the modified embodiment, the configuration of the two measuring devices can be varied. For example, the two measuring devices can be configured in series or in parallel on two branch lines branching off from a pipeline.

[0090] Furthermore, the two measuring devices can be positioned either downstream or upstream of the ultrafiltration membrane device 25. If positioned downstream of the ultrafiltration membrane device 25, the amount of colloidal particles (CL) in the treated water, i.e., the produced ultrapure water, can be directly measured. Conversely, if positioned upstream of the ultrafiltration membrane device 25, the amount of colloidal particles (CL) in the supply water to the ultrafiltration membrane device 25 can be measured. Moreover, if positioned on both the upstream and downstream sides of the ultrafiltration membrane device 25, the amount of colloidal particles (CL) removed by the ultrafiltration membrane device 25 can be directly measured.

[0091] In the above embodiments, the processor 26 may be composed of one or more hardware devices, and the type of hardware is not limited. For example, the processor may be composed of a programmable logic device such as a CPU (Central Processing Unit), an FPGA (Field Programmable Gate Array), or a dedicated circuit such as an ASIC (Application Specific Integrated Circuit) for performing specific processing.

[0092] The techniques disclosed herein can be appropriately combined with the various embodiments and / or variations described above. Furthermore, not limited to the embodiments described above, various structures may be employed without departing from the spirit of the invention.

[0093] The descriptions and illustrations above are detailed explanations of the technical aspects of this disclosure and are merely examples of the technology described herein. For instance, the descriptions of the structure, function, role, and effects described above are examples of the structure, function, role, and effects of the technical aspects of this disclosure. Therefore, it goes without saying that, without departing from the main technical intent of this disclosure, unnecessary deletions, additions, or substitutions can be made to the descriptions and illustrations above. Furthermore, to avoid confusion and facilitate understanding of the technical aspects of this disclosure, explanations of basic technical knowledge that do not require special explanation for implementing the technology of this disclosure have been omitted from the descriptions and illustrations above.

[0094] The disclosure of Japanese Patent Application No. 2025-020996, filed on February 12, 2025, is incorporated herein by reference in its entirety. All documents, patent applications and technical standards described in this specification are incorporated herein by reference to the same extent that they are specifically and individually described therein.

[0095] 10: Ultrapure water production equipment 11: Pre-treatment device 12: Primary Pure Water Unit 13: Secondary pure water device 14: Point of Use (POU) 21: Pure Water Tank (TK) 22: Ultraviolet (UV) irradiation device 23: Membrane Degassing Unit (MDG) 24: Non-regenerative mixed-bed ion exchange resin unit (Polisher) 25: Ultrafiltration membrane device (UF) 26: Processor 31: Measuring device 31A: Acoustic Microparticle Meter 31B: Optical microparticle meter 31C:TOC measurement 41: Membrane surface 42: Inner wall of fine pores CL: Colloidal particles CV: cavitation DL: Laser light IO: ions LA: Water supply pipeline LB: Drainage pipe LC: Circulation pipeline LD: Bypass line LR: Recycling Pipeline MP: microparticles P1: Water pump P2: Booster Pump RE: Ion exchange resin SL: Scattered light SW: Sound wave VA: Valves VB: Valves Xa: Measurement value Xb: Measurement value X_CL: Measurement value

Claims

1. An ultrapure water production apparatus, comprising a secondary pure water unit, the secondary pure water unit sequentially including a water pump, an ion exchange unit, and an ultrafiltration membrane unit, for removing impurities from primary pure water; wherein, On the upstream and / or downstream side of the ultrafiltration membrane device, there is a combination of at least one of the following: a first combination of an acoustic microparticle meter and an optical microparticle meter, and a second combination of an acoustic microparticle meter and a TOC meter.

2. The ultrapure water manufacturing apparatus as described in claim 1, which has a processor for controlling the water recovery rate of the ultrafiltration membrane device.

3. A method for producing ultrapure water, using an ultrapure water production apparatus as described in claim 1 or 2.

4. A method for operating and managing an ultrapure water manufacturing apparatus, comprising a secondary pure water unit, wherein the secondary pure water unit sequentially includes a water pump, an ion exchange unit, and an ultrafiltration membrane unit, and is used to remove impurities from primary pure water; wherein, The system uses a combination of at least one of a first combination of an acoustic microparticle meter and an optical microparticle meter and a second combination of an acoustic microparticle meter and a TOC meter located downstream of the ultrafiltration membrane device, and performs operation management based on measurements obtained from the combination.

5. A method for measuring colloidal particles, which is a method for measuring colloidal particles in a secondary pure water device, the secondary pure water device comprising, in sequence, a water pump, an ion exchange device, and an ultrafiltration membrane device, for removing impurities from primary pure water; wherein, The colloidal particles are measured using a combination of at least one of an acoustic particle meter and an optical particle meter disposed downstream of the ultrafiltration membrane device, or a combination of the acoustic particle meter and a TOC meter, and based on measurements obtained from the combination.

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