Water quality monitor and water treatment system

Abstract

A water quality monitor 20 comprises: a water treatment device 2 which has the function of removing impurities from water 1c, which is to be monitored for water quality, and discharges treated water 1d into which a specific component among the impurities has leaked; a measuring instrument 3 which is installed downstream from the water treatment device 2 and measures the concentration of the leaked specific component contained in the treated water 1d discharged from the water treatment device 2; and a monitoring unit 4 which detects fluctuations in the concentration of the leaked specific component in the treated water 1d.

Description

Water quality monitoring equipment and water treatment systems

[0001] The present invention relates to a water quality monitoring device and a water treatment system.

[0002] In the manufacturing process of semiconductor devices and liquid crystal display devices, ultrapure water, from which organic matter, ionic components, fine particles, bacteria, etc. have been highly removed, is used as wash water for cleaning these devices. Generally, an ultrapure water production system is composed of a primary pure water production system that produces pure water and a subsystem that further removes impurities from the pure water produced in the primary pure water production system. The primary pure water production system is mainly composed of an activated carbon device, an ion exchange resin device (e.g., a regenerative ion exchange resin device), a reverse osmosis (RO) membrane device, an ultraviolet irradiation device, a degassing device, etc. The subsystem is mainly composed of an ultraviolet irradiation device, an ion exchange device (e.g., a non-regenerative ion exchange resin device), a membrane degassing device, and an ultrafiltration membrane device. It is preferable to remove persistent organic matter such as TOC (total organic carbon) and urea in the primary pure water production system as much as possible.

[0003] Components such as silica, boron, and organic acids, such as TOC, are weak acids that are difficult to remove using ion exchange resins or RO membranes. Therefore, if silica, boron, or TOC components that are not removed in a primary pure water production system flow into a non-regenerative ion exchange resin device in a subsystem, a leak will occur early, causing a deterioration in the quality of the ultrapure water at the end. Therefore, in primary pure water production systems, it is necessary to remove weak acid components such as silica, boron, and TOC to the required end-use concentration levels using water treatment devices such as regenerative ion exchange resin devices. This requirement necessitates online monitoring technology to ensure that weak acid components such as silica, boron, and TOC have been successfully removed to the required end-use concentration levels within the primary pure water production system. However, the pure water produced by primary pure water production systems contains high concentrations of other impurities that coexist with components such as silica, boron, and TOC, which hinders the measurement of extremely low concentrations of silica, boron, TOC, and other components.

[0004] Patent Document 1 describes an operation management method for a regenerative ion exchange resin device. This operation management method utilizes the fact that the concentration of weak anions (such as silica, boron, and TOC) upstream of the regenerative ion exchange resin device is predictable with respect to the weak anions leaking from the regenerative ion exchange resin device. An ion removal device that removes ions other than the weak anions (such as silica, boron, and TOC) and a meter capable of measuring the concentration of the weak anions are installed upstream of the regenerative ion exchange resin device. The ion removal device is, for example, an electrodeionization device or an RO membrane device. The meter measures the concentration of the weak anions contained in the treated water from which the other ions have been removed. The concentration of the weak anions leaking from the regenerative ion exchange resin device is predicted based on the concentration measured by the meter.

[0005] JP 2014-233698 A

[0006] However, in the method described in Patent Document 1, the concentrations of weak anionic components (such as silica, boron, and TOC) in the upstream stage of the regenerative ion exchange resin device are measured, rather than in the treated water of the regenerative ion exchange resin device, which is the target of water quality management. Therefore, it is difficult to accurately determine the performance degradation of the regenerative ion exchange resin device itself.

[0007] An object of the present invention is to provide a water quality monitoring device and a water treatment system that can suppress the effects of impurities and accurately determine performance degradation of water treatment devices such as regenerative ion exchange resin devices online.

[0008] In order to achieve the above-mentioned object, according to one aspect of the present invention, a water quality monitoring device is provided, which is characterized by having a water treatment device that has the function of removing impurities from target water that is the subject of water quality monitoring and discharges treated water that has leaked specific components among the impurities, a measuring instrument that is installed downstream of the water treatment device and measures the concentration of the leaked specific component contained in the treated water discharged from the water treatment device, and a monitoring unit that detects fluctuations in the concentration of the leaked specific component in the treated water based on the measurement value measured by the measuring instrument.

[0009] According to another aspect of the present invention, there is provided a water treatment system comprising: a first water treatment device that treats water to be treated to produce treated water; a water quality monitoring device in which a portion of the treated water produced by the first water treatment device is supplied as target water for water quality monitoring, wherein the water quality monitoring device has the function of removing impurities from the target water and discharges treated water that has leaked specific components among the impurities; a measuring instrument installed downstream of the second water treatment device that measures the concentration of the leaked specific component contained in the treated water discharged from the second water treatment device; and a monitoring unit that detects fluctuations in the concentration of the leaked specific component based on the measurement value measured by the measuring instrument, and adjusts the operation of the first water treatment device or outputs an alarm based on the detection result of the concentration fluctuation.

[0010] According to the present invention, the influence of impurities can be suppressed, and the deterioration of the performance of a water treatment device such as a regenerative ion exchange resin device can be accurately determined online.

[0011] Fig. 1 is a block diagram showing the configuration of a water treatment system equipped with a water quality monitoring device according to a first embodiment of the present invention. Fig. 2 is a schematic diagram showing an example of a water treatment device for the water quality monitoring device shown in Fig. 1. Fig. 3 is a diagram for explaining the behavior of boron and the timing of chemical regeneration. Fig. 4 is a block diagram showing the configuration of a water treatment system equipped with a water quality monitoring device according to a second embodiment of the present invention. Fig. 5 is a diagram for explaining the behavior of resistivity and the timing of chemical regeneration. Fig. 6 is a diagram for explaining the behavior of TOC and the timing of chemical regeneration.

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the components described in the embodiments are merely examples and are not intended to limit the scope of the present invention.

[0013] (First embodiment) Fig. 1 is a block diagram showing the configuration of a water treatment system equipped with a water quality monitoring device according to a first embodiment of the present invention. In Fig. 1, solid arrows indicate piping (or flow paths), and dashed arrows indicate signal lines (or signals).

[0014] Referring to FIG. 1 , a water treatment system 10 is applicable to, for example, a primary pure water production system of an ultrapure water production plant, and includes a water treatment device 1 and a water quality monitoring device 20. The water treatment device 1 treats water to be treated 1a to produce treated water 1b. The treated water 1b is, for example, pure water, and its resistivity is generally in the range of 5 to 18 MΩ·cm. Here, for convenience, the resistivity of the treated water 1b is assumed to be in the range of 5 to 15 MΩ·cm. The water treatment device 1 can be referred to as a first water treatment device. The water treatment device 1 can include, for example, a regenerative ion exchange resin device, a reverse osmosis (RO) membrane separation device, an electro-deionized water production device (EDI), and the like. Here, the water treatment device 1 is assumed to be a chemical regenerative ion exchange resin device that regenerates ion exchange resin using chemicals.

[0015] A portion of treated water 1b produced by water treatment device 1 is supplied to water quality monitoring device 20 as treated water 1c, and the remainder is supplied to a point-of-use or a downstream treatment device (e.g., a subsystem). Treated water 1c can be called target water, which is the target of water quality monitoring. Water quality monitoring device 20 has water treatment device 2, measuring instrument 3, and monitoring unit 4.

[0016] In the water quality monitoring device 20, treated water 1c is supplied to a water treatment device 2. The water treatment device 2 has the function of removing impurities from the treated water 1c and discharges treated water 1d, which contains specific leaked impurity components. In the water treatment device 2, components other than the specific components (impurities) are removed, and the resulting water is discharged as concentrated water 1e. The concentrated water 1e may contain specific components that did not leak. Here, the specific components are weak acid components such as silica, boron, and TOC. The resistivity of the treated water 1d is preferably higher than that of the target water, the treated water 1c. This condition allows for the removal of only substances that could cause measurement noise for the specific leaked components, improving resistivity and increasing measurement accuracy. For example, the resistivity of the treated water 1d is preferably greater than 15 MΩ·cm. The water treatment device 2 can be referred to as a second water treatment device. The water treatment device 2 may be, for example, an electrodeionized water production device.

[0017] The measuring instrument 3 continuously measures the concentration of a specific component contained in the treated water 1d discharged from the water treatment device 2. The measuring instrument 3 supplies a signal indicating the measured value of the specific component to the monitoring unit 4. The measuring instrument 3 can be any one of a TOC meter, a silica meter, and a boron meter, or a combination of two or more thereof. The treated water 1f that has passed through the measuring instrument 3 is basically discharged outside the system, but from the standpoint of utilization efficiency, it may be returned to the upstream stage of the water treatment device 1 or used in another system.

[0018] The monitoring unit 4 monitors (detects) concentration fluctuations of specific leaked components based on the measured values ​​of the measuring instrument 3. The monitoring unit 4 includes an adjustment unit 5 and an alarm output unit 6. If the adjustment unit 5 detects a trend indicating a decline in the treatment performance of the water treatment device 1 for specific components based on the results of monitoring (detecting) concentration fluctuations, the adjustment unit 5 adjusts the operation of the water treatment device 1. For example, if the water treatment device 1 is a chemical regeneration type ion exchange resin device, the adjustment unit 5 regenerates the ion exchange resin using chemicals. The alarm output unit 6 outputs an alarm if the adjustment unit 5 detects a trend indicating a decline in the treatment performance of the water treatment device 1 for specific components based on the results of monitoring (detecting) concentration fluctuations. The alarm output unit 6 may include a display device that displays a warning message or a speaker that outputs a warning sound. Note that operational adjustment of the water treatment device 1 may also be performed by an administrator.

[0019] Next, the specific structure of the water treatment device 2 will be described. Here, the electrodeionized water production device that constitutes the water treatment device 2 will be described. Figure 2 is a schematic diagram showing the structure of the electrodeionized water production device. In Figure 2, both solid and dashed arrows indicate piping (or flow paths).

[0020] As shown in FIG. 2 , electrodeionized water production apparatus 2a has deionization compartment 22, concentration compartments 23 and 24, anion exchange membrane 25, and cation exchange membrane 26 between anode 21a and cathode 21b. Concentration compartment 23 is located on the anode side of deionization compartment 22, and anion exchange membrane 25 is located between concentration compartment 23 and deionization compartment 22. Concentration compartment 24 is located on the cathode side of deionization compartment 22, and cation exchange membrane 26 is located between concentration compartment 23 and deionization compartment 22. In this configuration, concentration compartment 23 also serves as the anode-side electrode chamber, and concentration compartment 24 also serves as the cathode-side electrode chamber. Note that electrodeionized water production apparatus 2a is not limited to the configuration shown in FIG. 2 . The anode-side electrode chamber and the cathode-side electrode chamber may be provided separately from concentration compartments 23 and 24. Alternatively, multiple concentration compartments and deionization compartments may be arranged alternately.

[0021] The deionization compartment 22 and the concentration compartments 23, 24 are each filled with an ion exchange resin. In this embodiment, the deionization compartment 22 is in the form of a mixed-bed resin of a cation exchange resin and an anion exchange resin. The concentration compartments 23, 24 may be filled with any ion exchange resin, or may not be filled with an ion exchange resin.

[0022] Treated water 1c is branched into two, one branched treated water 1c-1 which passes through deionization chamber 22, and the other branched treated water 1c-2 which passes through concentration chambers 23 and 24. Here, the flow rate of treated water 1c is set to 12 L / h, and the flow rates of branched treated waters 1c-1 and 1c-2 are both set to 6 L / h. The direction in which branched treated water 1c-1 flows through deionization chamber 22 and the direction in which branched treated water 1c-2 flows through concentration chambers 23 and 24 are opposite to each other (countercurrent directions).

[0023] In the electrodeionized water production apparatus 2a shown in FIG. 2, a portion of the treated water 1c (branched treated water 1c-1) flows through the deionization compartment 22, while the remainder of the treated water 1c (branched treated water 1c-2) flows through the concentration compartments 23 and 24. When a direct current is applied between the anode 21a and the cathode 21b, ions move between the deionization compartment 22 and the concentration compartment 23 via the anion exchange membrane 25, and ions move between the deionization compartment 22 and the concentration compartment 24 via the cation exchange membrane 26. Water dissociation occurs during the ion movement. Certain impurity components (such as silica, boron, and TOC) leak out, and the deionized treated water containing the leaked specific components is discharged as treated water 1d. The remaining specific components that do not leak out, as well as other impurities, are discharged as concentrated water (also serving as electrode water) 1e.

[0024] Although not shown in the figure, valves and flow meters are provided in the supply line for treated water 1c, the branch lines for branched treated water 1c-1 and 1c-2, the discharge line for concentrated water 1e, and the discharge line for treated water 1d, allowing the flow rates of treated water 1c, branched treated water 1c-1 and 1c-2, treated water 1d, and concentrated water 1e to be adjusted.

[0025] According to the water quality monitoring device 20 of the present embodiment, specific components (e.g., silica, boron, TOC) contained in treated water 1c, which is the target of water quality management, are leaked from the water treatment device 2 (electrodeionized water production device 2a), and other contaminant components are removed. By supplying treated water 1d containing the leaked specific components (e.g., silica, boron, TOC) to the measuring instrument 3, the measuring instrument 3 can measure extremely low concentrations of the specific components (e.g., silica, boron, TOC) without being affected by the other contaminant components. Therefore, using the water quality monitoring device 20, it is possible to accurately determine performance degradation of the water treatment device 1 (e.g., a regenerative ion exchange resin device) online.

[0026] Furthermore, by enabling online measurement of specific components (such as silica, boron, and TOC), the following effects are also achieved. Until now, there was no means for online detection of extremely low concentration leaks of specific components (such as silica, boron, and TOC) in the primary pure water production systems of ultrapure water production equipment, so operation adjustments were made with a safety margin in mind. Specifically, in the case of regenerative ion exchange resin equipment, the interval between chemical regenerations was set short and the amount of chemical used was set high. In the case of EDI, the current was set high and the flow rate was set low. In the case of RO membrane equipment, the recovery rate was set low and the amount of chemical (alkali) added was set high.

[0027] Online measurement using the water quality monitoring device 20 of this embodiment allows adjustment of the operation of the water treatment device 1 when a leak of a specific component (such as silica, boron, or TOC) is detected. Therefore, for example, in the case of a regenerative ion exchange resin device, the number of chemical regenerations can be reduced, significantly reducing the amount of regenerated chemicals used. In the case of an EDI, increasing the EDI current when a leak of a specific component is detected can prevent unnecessary power consumption, thereby reducing power consumption. In the case of an RO membrane device, the amount of chemical (alkali) added can be reduced.

[0028] Furthermore, when multiple water treatment devices such as EDIs are connected in parallel and some of the water treatment devices are used as standby systems, the number of standby water treatment devices is set to allow for a safety margin, but by enabling online measurement, it is also possible to reduce the number of standby systems.

[0029] Furthermore, the load amount flowing in from raw water varies greatly depending on the properties of the raw water, the amount of water used, and the amount of circulating water. Therefore, if the concentration of specific components could be monitored (detected) online, it would be possible to perform optimal maintenance and operational adjustments according to the state of the water treatment equipment.

[0030] It is difficult to achieve a high level of removal of other components in a typical desalination apparatus while maintaining a high leakage rate of a specific component. For example, the boron removal performance of an RO membrane apparatus is at least 40% removal rate, and the leakage rate is generally about 60% or less. Furthermore, EDI, due to its continuous electrical regeneration characteristics, has higher removal performance than an RO membrane apparatus, with a removal rate of at least 70% and a leakage rate of generally about 30% or less. The present inventors have conducted extensive research and successfully discovered a water treatment apparatus configuration that produces treated water with a resistivity exceeding 15 MΩ cm by sufficiently removing other impurity components while maintaining a leakage rate of a specific component of 70% or more (a removal rate of 30% or less).

[0031] The results of this study are described in detail below. In the electrodeionized water production apparatus 2a shown in FIG. 2 , the leakage rate of specific components (e.g., silica, boron, TOC) and the quality of the treated water 1d (treated water quality) are affected by the type and packing rate of the ion exchange resin packed in the deionization chamber 22, the flow rate of water passed through the deionization chamber 22, and the current value passed through the chamber. The results of this study are described below. Here, treated water 1c with a resistivity of 17 MΩ cm was used as the raw water. The deionization chamber 22 contained a mixed-bed resin of anion exchange resin and anion exchange resin in a 1:1 ratio. The packing rate refers to the value obtained by applying a DC voltage between the anode 21a and cathode 21b while passing water through the deionization chamber 22 filled with ion exchange resin to regenerate the ion exchange resin, and then dividing the apparent volume of the ion exchange resin in its free state when removed from the deionization chamber 22 by the volume of the deionization chamber 22. The free state refers to a state in which the ion exchange resin is not confined in spaces such as the deionization compartment 22 and the concentration compartments 23 and 24 .

[0032] Comparison of Strongly Basic Resin and Weakly Basic Resin In Evaluation Example 1, the mixed bed resin in the deionization compartment 22 was composed of a strongly acidic cation exchange resin and a strongly basic type I anion exchange resin. In contrast, in Evaluation Example 2, the mixed bed resin in the deionization compartment 22 was composed of a strongly acidic cation exchange resin and a weakly basic anion exchange resin. For Evaluation Examples 1 and 2, the electrodeionized water production apparatus 2a was operated at a packing ratio (ratio of the amount of resin filled in the deionization compartment to the volume of the deionization compartment) of 1.10, a flow rate of 6 L / h, and a current value of 10 mA to evaluate the treated water quality and boron (B) leakage rate. The B leakage rate is the ratio of the boron concentration in treated water 1d to the boron concentration in raw water (treated water 1c). The evaluation results are shown in Table 1.

[0033]

[0034] As can be seen from Table 1, in Evaluation Example 1, the treated water quality increased from the raw water resistivity of 17 MΩ cm to 17.62 MΩ cm, but the B leakage rate was 16%. In contrast, in Evaluation Example 2, the B leakage rate was 100%, but the treated water quality decreased from the raw water resistivity of 17 MΩ cm to 13.87 MΩ cm. From these results, it was found that making the anion exchange resin of the mixed bed resin strongly basic is effective in increasing the treated water quality to a resistivity value higher than that of the raw water. Note that, because boron is a substance that does not react well with a resistivity meter, whether 100% or 16% of boron leaks, it basically has almost no effect on the resistivity of the treated water quality.

[0035] (Comparison of Filling Rates) Evaluation Example 1 was the same as that shown in Table 1. In both Evaluation Examples 3 and 4, the mixed-bed resin in the deionization chamber 22 was composed of a strongly acidic cation exchange resin and a strongly basic type I anion exchange resin, as in Evaluation Example 1. The filling rate was 1.10 in Evaluation Example 1, 1.05 in Evaluation Example 2, and 1.00 in Evaluation Example 3. For Evaluation Examples 1 and 2, the electrodeionized water production apparatus 2a was operated at a flow rate of 6 L / h and a current value of 10 mA to evaluate the treated water quality and B leakage rate. For Evaluation Example 3, the electrodeionized water production apparatus 2a was operated at a flow rate of 6 L / h and a current value of 20 mA to evaluate the treated water quality and B leakage rate. The evaluation results are shown in Table 2.

[0036]

[0037] As can be seen from Table 2, when the packing rate was increased from 1.10 times (Evaluation Example 1) to 1.05 times (Evaluation Example 2), the treated water quality remained almost the same, but the B leakage rate increased from 16% to 72%. On the other hand, in Evaluation Example 3 (packing rate 1.00 times), even though the current value was increased to 20 mA, the water quality was less than 5 MΩ cm, and the B leakage rate could not be evaluated. From these results, it was found that increasing the mixed bed resin packing rate to 1.05 times is effective in increasing the resistivity value of the treated water quality and the B leakage rate.

[0038] (Comparison of Strongly Basic Type I and Type II) Evaluation Example 3 is the same as that shown in Table 2. In Evaluation Example 4, the mixed bed resin in the deionization chamber 22 was composed of a strongly acidic cation exchange resin and a strongly basic Type II anion exchange resin, and the filling rate was 1.05. For Evaluation Examples 3 and 4, the electrodeionized water production apparatus 2a was operated at a flow rate of 6 L / h and a current value of 10 mA to evaluate the treated water quality and B leakage rate. The evaluation results are shown in Table 3.

[0039]

[0040] As can be seen from Table 3, by changing the strongly basic type I anion exchange resin in the mixed bed resin to a strongly basic type II anion exchange resin, the B leakage rate increased from 72% to 83% while the treated water quality remained almost the same. This shows that using a strongly basic type II anion exchange resin is effective in increasing the B leakage rate.

[0041] (Comparison Based on Different Current Values) Evaluation Examples 3 and 4 are the same as those shown in Table 3. In Evaluation Examples 5 and 6, the mixed-bed resin in the deionization compartment 22 was composed of a strongly acidic cation exchange resin and a strongly basic type I anion exchange resin, with a packing ratio of 1.05. In Evaluation Examples 7 and 8, the mixed-bed resin in the deionization compartment 22 was composed of a strongly acidic cation exchange resin and a strongly basic type II anion exchange resin, with a packing ratio of 1.05. For Evaluation Examples 5 and 7, the electrodeionized water production apparatus 2a was operated at a flow rate of 6 L / h and a current value of 20 mA to evaluate the treated water quality and B leakage rate. For Evaluation Examples 6 and 8, the electrodeionized water production apparatus 2a was operated at a flow rate of 6 L / h and a current value of 4 mA to evaluate the treated water quality and B leakage rate. The evaluation results are shown in Table 4.

[0042]

[0043] The results in Table 4 show that when a strongly basic type I anion exchange resin is used as the mixed bed resin (Evaluation Examples 2 and 6), it is effective to set the current value to 4 to 10 mA and the current amount per flow rate to 0.67 to 1.67 mA·h / L. Also, when a strongly basic type II anion exchange resin is used as the mixed bed resin (Evaluation Examples 3, 7, and 8), it is effective to set the current value to 4 to 20 mA and the current amount per flow rate to 0.67 to 3.33 mA·h / L.

[0044] Further investigation was carried out based on the evaluation results of Evaluation Examples 1 to 8 described above, and as a result, it was found that satisfying at least one of the following conditions is effective in sufficiently removing other components that are impurities and obtaining treated water with a resistivity value of more than 15 MΩ cm:

[0045] (Condition 1) The deionization compartment 22 is filled with at least an anion exchange resin, and it is preferable that at least a portion of the filled anion exchange resin contains a strongly basic type II anion exchange resin. (Condition 2) The leakage rate of a specific component is in the range of 70% to 100%. (Condition 3) When the current value applied to the electrodeionized water production device 2a is I [mA] and the flow rate of water passed through the deionization compartment 22 is F [L / h], the value expressed by I / F = X is in the range of 0.6 to 4.0. (Condition 4) The space velocity of water passed through the deionization compartment 22 is 150 h －１ This makes it possible to increase the leakage rate of a specific component to 70% or more.

[0046] Next, the operational adjustment of the water treatment device 1 in the water treatment system 10 shown in FIG. 1 will be specifically described. Generally, a boron meter is designed to detect the difference between boron-containing water and boron-removed water using a substance that selectively adsorbs boron. If the feed water contains components that interfere with the boron-selective adsorption substance, the boron concentration cannot be accurately measured. For this reason, 15 MΩ·cm is set as the index of the resistivity of the feed water for the boron meter. In the water quality monitoring device 20 of this embodiment, the water treatment device 2 (electrodeionized water production device 2a) can produce treated water with a resistivity value exceeding 15 MΩ·cm, so a boron meter can be used as the measuring instrument 3. Here, a chemical regenerating ion exchange resin device is used as the water treatment device 1, and the electrodeionized water production device 2a shown in FIG. 2 is used as the water treatment device 2.

[0047] Figure 3 is a diagram illustrating the behavior of boron and the timing of chemical regeneration. In Figure 3, the vertical axis represents the boron concentration [ppb], and the horizontal axis represents the date. As shown in Figure 3, chemical regeneration (switching of series) of the chemical regeneration-type ion exchange resin device was performed when the boron concentration in the treated water 1d of the electrodeionized water production device 2a was detected to be increasing to 0.1 ppb. It was found that this operational adjustment allowed the boron concentration in the treated water 1c of the chemical regeneration-type ion exchange resin device to be maintained at the required terminal level.

[0048] A silica meter or TOC meter may be used instead of the boron meter. When a silica meter or TOC meter is used, chemical regeneration (switching of the system) of the chemical regeneration-type ion exchange resin device is performed when an increasing trend in the silica concentration or TOC concentration in the treated water 1d of the electrodeionized water production system 2a is detected. This operational adjustment also allows the silica concentration and TOC concentration in the treated water 1c of the chemical regeneration-type ion exchange resin device to be maintained at the required terminal level, just as when a boron meter is used.

[0049] It is known that boron begins to leak before silica during the process of leakage of ion components (a decrease in resistivity) from an ion regeneration resin tower of a regenerative ion exchange resin device, etc. Considering this characteristic, it is preferable to measure the boron concentration and adjust operation accordingly.

[0050] Second Embodiment Fig. 4 is a block diagram showing the configuration of a water treatment system equipped with a water quality monitoring device according to a second embodiment of the present invention. In Fig. 4, solid arrows indicate piping (or flow paths), and dashed arrows indicate signal lines (or signals).

[0051] The water quality monitoring device 21 shown in Figure 4 has the same configuration as the water quality monitoring device 20 shown in Figure 1, except that a measuring instrument 3a is used instead of the measuring instrument 3. The water treatment device 1 is also the same as that shown in Figure 1. The same components as those shown in Figure 1 are assigned the same reference numerals, and detailed descriptions thereof will be omitted.

[0052] In the water quality monitoring device 21, treated water 1d from the water treatment device 2 (electrodeionized water production device 2a) is supplied to a measuring instrument 3a. The measuring instrument 3a is any one of a resistivity meter, a pH meter, and a conductivity meter. The measuring instrument 3a continuously measures the resistivity, pH, or conductivity of the treated water 1d and supplies a signal indicating the measured value to the monitoring unit 4. The treated water 1f that passes through the measuring instrument 3a is basically discharged outside the system, but from the standpoint of utilization efficiency, it may be returned to the upstream stage of the water treatment device 1 or used in another system.

[0053] The monitoring unit 4 indirectly monitors (detects) the concentration fluctuation of a specific leaked component based on the measurement value of the measuring instrument 3a. Here, the principle of indirect monitoring will be briefly explained. In the EDI (water treatment device 2), a cation component (Na 2 ) that exists as a counter ion of a weak acid component is detected. ＋ etc.), and H generated by the dissociation of water proceeding inside the EDI ＋ By replacing with H, the pH of the treated water 1d shifts to the acidic side. ＋ Since the ionic limiting molar conductivity of 1d is the largest among the cationic components, the conductivity of the treated water 1d increases and the resistivity (the reciprocal of the conductivity) decreases. By utilizing this characteristic, the treated water 1d can be measured with a measuring instrument 3a such as a pH meter, resistivity meter, or conductivity meter, and the fluctuation in the concentration of a specific leaked component can be indirectly detected from the measured value.

[0054] Figure 5 is a diagram illustrating resistivity behavior and the timing of chemical regeneration. In Figure 5, the vertical axis represents resistivity value [MΩ·cm], and the horizontal axis represents date. A resistivity meter was used as the measuring instrument 3a. As shown in Figure 5, chemical regeneration (switching of series) of the chemical regeneration-type ion exchange resin device was performed when the resistivity value of the treated water 1d of the electrodeionized water production device 2a was detected to be decreasing to approximately 16 MΩ·cm. It was found that this operational adjustment allowed the concentrations of specific components (such as boron, silica, and TOC) contained in the treated water 1c of the chemical regeneration-type ion exchange resin device to be maintained at the required terminal level.

[0055] A pH meter or conductivity meter may be used instead of a resistivity meter, and chemical regeneration (switching of the system) may be performed when a tendency for the pH or conductivity of the treated water 1d to decrease is detected. In this case, too, the concentrations of specific components (such as boron, silica, and TOC) contained in the treated water 1c of the chemical regeneration-type ion exchange resin device can be maintained at the required terminal level.

[0056] Generally, meters such as resistivity meters, pH meters, and conductivity meters are relatively inexpensive compared to boron meters, so the water quality monitoring device 21 of this embodiment can reduce the device cost compared to the water quality monitoring device 20 of the first embodiment.

[0057] (Another Embodiment) In the water quality monitoring device 20 shown in FIG. 1 , the water treatment device 2 (electrodeionized water production device 2 a) is configured to leak 90% or more of the TOC component as a specific component, and a TOC meter is used as the measuring instrument 3. FIG. 6 is a diagram illustrating the behavior of TOC and the timing of chemical regeneration. FIG. 6 shows the measurement results of the TOC meter, along with the measurement results of the resistivity at the outlet of the water treatment device 2 for comparison. In FIG. 6 , the vertical axis represents the TOC concentration [ppb] and the resistivity value [MΩ·cm], and the horizontal axis represents the date. As shown in FIG. 6 , the resistivity value at the inlet of the water treatment device 2 fluctuated between 5 and 15 MΩ·cm, but the water quality at the outlet of the water treatment device 2 exceeded 15 MΩ·cm. This embodiment enables accurate analysis of the TOC concentration. It was confirmed that by performing chemical regeneration (series switching) of the chemical regeneration type ion exchange resin device so that the TOC concentration of the treated water 1d of the water treatment device 2 does not exceed approximately 20 ppb, it is possible to maintain the required TOC concentration at the end of the subsystem installed in the subsequent stage.

[0058] Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the above embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

[0059] This application claims priority based on Japanese Patent Application No. 2024-110204, filed on July 9, 2024, the disclosure of which is incorporated herein in its entirety by reference.

[0060] REFERENCE SIGNS LIST 1, 2 Water treatment device 1b, 1c, 1d Treated water 3 Measuring instrument 4 Monitoring unit 5 Adjustment unit 6 Alarm output unit 10 Water treatment system 20 Water quality monitoring device

Claims

1. A water quality monitoring device comprising: a water treatment device that has the function of removing impurities from target water that is the subject of water quality monitoring and that discharges treated water that has leaked specific components of the impurities; a measuring instrument that is installed downstream of the water treatment device and that measures the concentration of the specific leaked component contained in the treated water discharged from the water treatment device; and a monitoring unit that detects fluctuations in the concentration of the specific leaked component in the treated water based on the measurement value measured by the measuring instrument.

2. The water quality monitoring device according to claim 1, wherein the resistivity of the treated water from the water treatment device is higher than the resistivity of the target water.

3. The water quality monitoring device according to claim 2, wherein the resistivity of the treated water from the water treatment device is greater than 15 MΩ·cm.

4. The water quality monitoring device according to any one of claims 1 to 3, wherein the water treatment device is an electrodeionization water production device.

5. The water quality monitoring device according to claim 4, wherein the electrodeionized water production device is provided with a deionization chamber through which a portion of the target water passes, and the value expressed by I÷F=X is within the range of 0.6 to 4.0, where I [mA] is the current value passed through the electrodeionized water production device and F [L / h] is the flow rate of water passed through the deionization chamber.

6. The water quality monitoring device according to claim 4, wherein the electrodeionized water production apparatus comprises a deionization chamber through which a portion of the target water passes, the deionization chamber being filled with at least an anion exchange resin, and at least a portion of the filled anion exchange resin includes a strongly basic type II anion exchange resin.

7. The electrodeionization water production apparatus has a deionization chamber through which a portion of the target water passes, and the space velocity of the water passing through the deionization chamber is 150 h －１ 5. The water quality monitoring device of claim 4, wherein the water quality monitoring device is larger than the water quality monitoring device of claim 4.

8. A water quality monitoring device according to any one of claims 1 to 3, characterized in that the leakage rate of the specific component is in the range of 70% to 100%.

9. A water quality monitoring device according to any one of claims 1 to 3, characterized in that the specific component is any one of silica, boron, and TOC.

10. A water quality monitoring device according to any one of claims 1 to 3, characterized in that the measuring instrument is one of a silica meter, a boron meter, a TOC meter, a resistivity meter, a conductivity meter, and a pH meter.

11. A water treatment system comprising: a first water treatment device that treats water to be treated to produce treated water; and a water quality monitoring device that supplies a portion of the treated water produced by the first water treatment device as target water for water quality monitoring, wherein the water quality monitoring device comprises: a second water treatment device that has the function of removing impurities from the target water and discharges treated water that has leaked specific components of the impurities; a measuring instrument that is installed downstream of the second water treatment device and measures the concentration of the leaked specific component contained in the treated water discharged from the second water treatment device; and a monitoring unit that detects fluctuations in the concentration of the leaked specific component based on the measurement value measured by the measuring instrument, and adjusts the operation of the first water treatment device or outputs an alarm based on the detection result of the concentration fluctuation.

12. The water treatment system according to claim 11, wherein the first water treatment device is a chemical regeneration type ion exchange resin device, and the operational adjustment is chemical regeneration.

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