Water treatment apparatus, installation method of dissolved gas measuring device, and dissolved gas measuring method

Abstract

To provide a water treatment apparatus that can shorten the time required from starting of water conduction to a dissolved gas measuring device until stabilization of a dissolved gas concentration.SOLUTION: A water treatment apparatus for treatment of target water for manufacturing treatment water includes a dissolved gas measuring device 9 constituted for conduction of measurement target water which is a part of target water or a part of treatment water. The dissolved gas measuring device 9 includes a supply hole 14 and a discharge hole 15 for conduction of the measurement target water. The dissolved gas measuring device 9 is installed in a manner that measurement target water supplied from the supply hole 14 flows upwardly in a direction crossing a horizontal direction from the discharge hole 15.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a water treatment device, a method for installing a dissolved gas measurement device, and a method for measuring dissolved gas. [Background technology]

[0002] In the semiconductor manufacturing process, pure water (including ultrapure water), from which impurities (e.g., organic matter, ionic components, fine particles, bacteria, etc.) have been highly removed, is used as water for washing electronic components such as silicon wafers. When pure water (ultrapure water) is used for washing electronic components, if oxidizing substances such as oxygen or hydrogen peroxide are dissolved in the pure water, it can cause a natural oxide film to form on the surface of the electronic components. For this reason, for example, in ultrapure water production systems, degassing devices (membrane degassing devices, catalytic degassing devices, etc.) are installed in the primary and secondary pure water production systems (subsystems) to reduce the concentration of oxidizing substances contained in the pure water (ultrapure water).

[0003] Generally, in water treatment systems that produce treated water at a pure water (ultrapure water) level, a dissolved oxygen (DO) meter is used to measure the concentration of oxidizing substances contained in the water to be treated and the treated water. Patent Document 1 describes a water treatment device for ultrapure water, in which the water to be treated passes through an ultraviolet irradiation device, a membrane degassing device, an ion exchange device, and an ultrafiltration device in sequence, and which is equipped with a DO meter that measures the dissolved oxygen (DO) concentration in the water to be treated, either before or after the ultraviolet irradiation device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-264630 Summary of the Invention [Problem to be solved by the invention]

[0005] However, until now, there has been no clear explanation for the optimal installation direction of dissolved gas measurement devices such as DO meters in water treatment systems that produce treated water at a pure water (ultrapure water) level. For this reason, depending on the installation direction of the dissolved gas measurement device, it can be difficult to remove the inflowing air, and as a result, it takes time from the start of water flow through the dissolved gas measurement device until the dissolved gas concentration stabilizes.

[0006] An object of the present invention is to provide a water treatment device, a method for installing a dissolved gas measurement device, and a method for measuring dissolved gases that can shorten the time required from the start of water flow through the dissolved gas measurement device until the dissolved gas concentration stabilizes. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, according to one aspect of the present invention, there is provided a water treatment device that treats water to be treated to produce treated water, the water treatment device comprising a dissolved gas measuring device configured to pass measurement target water, which is a part of the water to be treated or a part of the treated water, the dissolved gas measuring device having a supply hole and a discharge hole for passing the measurement target water, and the dissolved gas measuring device is installed so that the measurement target water supplied from the supply hole flows upward from the discharge hole in a direction intersecting the horizontal direction.

[0008] According to another aspect of the present invention, there is provided a method for installing a dissolved gas measurement device that measures the concentration of dissolved gas contained in water to be measured, the dissolved gas measurement device having a supply hole and a discharge hole for passing the water to be measured, and the dissolved gas measurement device is installed so that the water to be measured supplied from the supply hole flows upward through the discharge hole in a direction intersecting the horizontal direction.

[0009] According to yet another aspect of the present invention, there is provided a method for measuring the dissolved gas concentration in a water treatment device that treats water to produce treated water by treating the water to be treated or a sample water that is a sample water, by attaching a dissolved gas measuring device configured to pass the sample water or the sample water that is a sample water to the water treatment device, the dissolved gas measuring device having an opening and a supply hole and a discharge hole opposite the opening for passing the sample water; a sensor unit that is detachably attached to the opening of the chamber and measures a current value corresponding to the dissolved gas concentration in the sample water that has passed through the chamber; and a cable that is connected to the sensor unit on the side opposite the chamber for transmitting signals from the sensor unit. The dissolved gas measuring method includes the steps of: installing the dissolved gas measuring device so that the chamber is on the upper side and the cable is on the lower side when the chamber is empty; passing the sample water through the chamber by supplying the sample water from the supply hole into the chamber and discharging it from the discharge hole; and measuring the dissolved gas concentration using the sensor unit from the start of passing the sample water. [Effects of the Invention]

[0010] According to the present invention, it is possible to reduce the time required from the start of water flow into the dissolved gas measurement device until the dissolved gas concentration becomes stable. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a block diagram showing a configuration of a water treatment device according to an embodiment of the present invention; [Figure 2] FIG. 1 is a schematic diagram showing the configuration of a dissolved gas measuring device. [Figure 3] FIG. 10 is a schematic diagram showing the installation direction of a dissolved gas measurement device of a comparative example. [Figure 4] FIG. 10 is a diagram showing the change in dissolved oxygen concentration from the start of water flow in a comparative example. [Figure 5] FIG. 5 is an enlarged view of a portion of the graph shown in FIG. [Figure 6]FIG. 10 is a graph showing the change in dissolved oxygen concentration from the start of water flow in an embodiment of the present invention. [Figure 7] FIG. 7 is an enlarged view of a portion of the graph shown in FIG. 6. [Figure 8] FIG. 2 is a schematic diagram for explaining an example of an installation angle range of the dissolved gas measurement device. [Figure 9] FIG. 2 is a schematic diagram illustrating an example of a wetting prevention mechanism. DETAILED DESCRIPTION OF THE INVENTION

[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] FIG. 1 is a block diagram showing the configuration of a water treatment device according to one embodiment of the present invention. The water treatment device 1 is a device that treats water to be treated to produce treated water (pure water or ultrapure water), and in this embodiment, it is composed of a secondary pure water production system (subsystem) that treats primary pure water, but is not limited to this. The water treatment device 1 may also be a so-called primary pure water production system that produces primary pure water from treated water produced by a pretreatment device.

[0014] 1, the water treatment device 1 includes, but is not limited to, a tank 2, a pump 3, a heat exchanger (HE) 4, an ultraviolet oxidation device (UVox) 5, a membrane degassing device (MD) 6, a cartridge polisher (CP) 7, and an ultrafiltration membrane device (UF) 8. The water treatment device 1 may also include other treatment devices (unit operation devices).

[0015] Tank 2 stores primary pure water produced by a primary pure water production system (not shown). Tank 2 communicates with heat exchanger 4 via piping, and this piping is provided with pump 3. Heat exchanger 4 communicates with ultraviolet oxidation device 5 via piping. Ultraviolet oxidation device 5 communicates with membrane degassing device 6 via piping. Membrane degassing device 6 communicates with cartridge polisher 7 via piping. Cartridge polisher 7 communicates with ultrafiltration membrane device 8 via piping.

[0016] A pump 3 pumps the pure water stored in a tank 2. The water passes through a heat exchanger 4, an ultraviolet oxidation device 5, a membrane degassing device 6, a cartridge polisher 7, and an ultrafiltration membrane device 8, in that order. The ultraviolet oxidation device 5 irradiates the water with ultraviolet light to decompose organic matter in the water. The membrane degassing device 6 removes dissolved gases from the water. The cartridge polisher 7 uses an ion exchange membrane to remove ions from the water. The ultrafiltration membrane device 8 uses an ultrafiltration membrane to remove fine particles from the water. The filtered water (permeate) from the ultrafiltration membrane device 8 is provided to the point of use as treated water (ultrapure water) from the water treatment device 1. The treated water (ultrapure water) not provided to the point of use is returned to the tank 2 via a circulation line. The heat exchanger 4, ultraviolet oxidation device 5, membrane degassing device 6, cartridge polisher 7, and ultrafiltration membrane device 8 can be those used in general secondary pure water production systems.

[0017] The water treatment device 1 further includes a dissolved gas measuring device 9. The dissolved gas measuring device 9 measures the dissolved gas concentration in measurement target water, which is a part of the water to be treated or a part of the treated water. Here, the water to be treated includes water supplied to each water treatment element (unit operation device) of the water treatment device 1. The treated water includes the treated water produced by the water treatment device 1 (the filtered water (permeate) of the ultrafiltration membrane device 8) as well as water flowing through the circulation line. In this embodiment, the dissolved gas measuring device 9 is configured to allow the measurement target water, which is a part of the treated water produced by the water treatment device 1, to pass through it. The dissolved gas measuring device 9 may be located at any position in the water treatment device 1. For example, the dissolved gas measuring device 9 may be located downstream of the ultraviolet oxidation device 5 or the membrane degassing device 6. In this case, the measurement target water, which is a part of the water to be treated, is allowed to pass through the dissolved gas measuring device 9.

[0018] Fig. 2 is a schematic diagram showing the configuration of the dissolved gas measurement device 9. Fig. 2(a) shows a schematic cross section of each component, excluding a part of the dissolved gas measurement device 9. Fig. 2(b) shows a schematic internal structure of the chamber of the dissolved gas measurement device 9.

[0019] As shown in FIG. 2(a), the dissolved gas measuring device 9 has a chamber 10, a sensor unit 20, and a cable 30. The chamber 10 has pipe fittings 16 and 17. The pipe fitting (inlet) 16 is connected to a branch pipe branching off from the outlet pipe of the ultrafiltration membrane device 8. The pipe fitting (outlet) 17 is connected to a pipe communicating with the tank 2 or a pipe for discharging the water to the outside of the system. The water to be measured is supplied from the pipe fitting 16 to the chamber 10 and then discharged from the pipe fitting 17.

[0020] The tip portion of sensor unit 20 is housed in chamber 10. Sensor unit 20 is used to measure the dissolved gas concentration of the measurement target water flowing inside chamber 10, and measures a current value corresponding to the dissolved gas concentration. Cable 30 is connected to the side of sensor unit 20 opposite chamber 10, and transmits a signal (current value) from sensor unit 20 to a main measurement device (not shown). The main measurement device performs calculations to convert the signal (current value) from sensor unit 20 into a dissolved gas concentration. The main measurement device has a function to output information including, for example, the measurement value of the dissolved gas concentration, which is the calculation result.

[0021] As shown in FIG. 2(b), chamber 10 has an opening 11, and a supply hole 14 and a discharge hole 15 are provided in a portion facing opening 11. Supply hole 14 is provided in the center of first surface 12 facing opening 11, and communicates with pipe mounting portion 16. Discharge hole 15 is provided in side surface 13 adjacent to first surface 12, and communicates with pipe mounting portion 17. Discharge hole 15 may be provided in any portion of first surface 12 as long as it is adjacent to the center.

[0022] The sensor unit 20 is detachably attached to the opening 11 of the chamber 10. For example, a dissolved oxygen (DO) meter using a diaphragm electrode can be used as the sensor unit 20, but the present invention is not limited to this. In this example, a dissolved oxygen meter is used as the sensor unit 20. The sensor unit 20 has a diaphragm at its tip and measures the current value generated by oxygen that has permeated the diaphragm.

[0023] In the water treatment device 1 of this embodiment, if air or bubbles are mixed into the chamber 10, the dissolved oxygen concentration cannot be accurately measured by the sensor unit 20. For example, if air is mixed into the chamber 10 when the measurement target water starts to flow, the dissolved oxygen concentration of the measurement target water will not stabilize until the air mixed into the chamber 10 is discharged. Note that the bubbles may not only be air bubbles, but may also include bubbles of dissolved gases (such as dissolved oxygen and dissolved hydrogen) that were not completely dissolved.

[0024] In the water treatment device 1 of this embodiment, the dissolved gas measurement device 9 is installed so that the measurement target water supplied from the supply hole 14 flows upward through the discharge hole 15 in a direction intersecting the horizontal direction. Here, the "direction intersecting the horizontal direction" includes not only a direction perpendicular to the horizontal direction (vertical direction) but also a direction tilted from the vertical direction. In the following, the configuration will be described in detail assuming that the measurement target water flows upward relative to the vertical direction. Specifically, the dissolved gas measurement device 9 is installed so that the chamber 10 is on the upper side and the cable 30 is on the lower side. With this installation, air (air bubbles) mixed into the chamber 10 moves toward the first surface 12 due to buoyancy, and then moves to the discharge hole 15 along with the flow of the water to be measured. This allows the air bubbles to be discharged outside the chamber 10. In this way, since the air (air bubbles) mixed into the chamber 10 can be easily discharged, the time required from the start of the flow of the water to be measured until the dissolved gas concentration stabilizes can be shortened.

[0025] The effect of reducing the time will be specifically described below. When measuring high concentrations of dissolved oxygen, such as those caused by aeration in a typical biological tank, the impact of air contamination (air bubbles) is small. In contrast, when measuring ultra-low concentrations of dissolved oxygen in water to be measured, such as pure water (ultrapure water), even a small amount of air bubbles can significantly affect the measurement. This embodiment is configured to measure the dissolved oxygen concentration in a secondary pure water production system (subsystem), and measures ultra-low concentrations of dissolved oxygen, such as less than 10 ppb. Focusing on the impact of even small amounts of air bubbles, the inventors conducted a detailed investigation into the ease with which air bubbles trapped in the chamber 10 escape depending on the installation direction of the dissolved gas measurement device 9, and the time required for the dissolved gas concentration to stabilize after water flow begins.

[0026] (Comparative Example) FIG. 3 shows the installation direction of the dissolved gas measuring device 9 of the comparative example. In this comparative example, a dissolved oxygen meter (510 / flow chamber type manufactured by Orbisphere) was used as the dissolved gas measuring device 9. First, the chamber 10 was emptied, and then the pipe mounting part 16 was connected to the evaluation pipe to allow air to be mixed into the chamber 10. Then, as shown in FIG. 3, the dissolved gas measuring device 9 was installed so that the cable 30 was on the upper side and the chamber 10 was on the lower side. After installation was completed, the water flow rate was adjusted to 180 ml / min, and the flow of the water to be measured was started, and the dissolved oxygen concentration was continuously measured using the sensor part 20.

[0027] Figure 4 shows the change in dissolved oxygen (DO) concentration from the start of water flow in the comparative example. Figure 5 is an enlarged view of a portion of the graph shown in Figure 4. As shown in Figures 4 and 5, in the installation orientation of the comparative example, the time required for the dissolved oxygen concentration to stabilize (time to rise) from the start of water flow was 400 minutes. This is thought to be because air (air bubbles) mixed into chamber 10 moved in the direction opposite discharge hole 15 due to buoyancy and remained in chamber 10, and as a result, it took time for the air bubbles to disappear due to the flow of the water to be measured.

[0028] (Example) In this example, the dissolved gas measuring device 9 was installed so that the chamber 10 was on the upper side and the cable 30 was on the lower side, but the flow of the water to be measured was started under the same conditions and procedures as in this comparative example, and the dissolved oxygen concentration was continuously measured using the sensor unit 20.

[0029] Figure 6 shows the change in dissolved oxygen (DO) concentration from the start of water flow in this example. Figure 7 is an enlarged view of a portion of the graph shown in Figure 6. As shown in Figures 6 and 7, with the installation orientation of this example, it took 30 minutes from the start of water flow until the dissolved gas concentration stabilized (time to start-up).

[0030] According to this example, the time from the start of water flow to start-up could be reduced from 400 minutes to 30 minutes, compared to the comparative example. 3, it is possible to provide the pipe mounting portion 17 on the side surface of the chamber 10. However, even in this case, air bubbles tend to accumulate in the upper part of the chamber 10, and it takes a long time from the start of water flow until the dissolved gas concentration stabilizes.

[0031] Furthermore, according to the water treatment device 1 of this embodiment, dissolved gas measurement can be carried out easily and in a short time. This effect will be specifically described below.

[0032] Conventionally, dissolved gas measurement has been performed using the following procedure. First, the dissolved gas measurement device 9 is installed with the cable 30 on the upper side and the chamber 10 on the lower side. Next, the sensor unit 20 is removed from the chamber 10, and measurement target water is supplied to the chamber 10 until it is filled with water. Next, the sensor unit 20 is attached to the chamber 10 while preventing air from entering the chamber 10 when the chamber 10 is filled with water. After that, the measurement target water is supplied into the chamber 10 through the supply hole 14 and discharged through the discharge hole 15, and the dissolved gas concentration is measured using the sensor unit 20 from the start of water flow. In this case, the time required for the dissolved gas concentration to stabilize from the start of water flow corresponds to the rise time (400 minutes) shown in Figures 4 and 5. Conventionally, the cable 30 is generally placed on the upper side because there is a possibility that the cable 30 may get wet.

[0033] In contrast, in the water treatment device 1 of this embodiment, dissolved gas measurement is performed using the following procedure. First, with the chamber 10 empty, the dissolved gas measurement device 9 is installed so that the chamber 10 is on the upper side and the cable 30 is on the lower side. Then, water to be measured is supplied into the chamber 10 through the supply hole 14 and discharged through the discharge hole 15, and the dissolved gas concentration is measured using the sensor unit 20 from the start of water flow. In this case, the time required for the dissolved gas concentration to stabilize corresponds to the time (30 minutes) until the measurement is started, as shown in Figures 6 and 7. This dissolved gas measurement method eliminates the need for the conventional process of filling the chamber 10 with water, thereby simplifying the work process. Furthermore, the short time required from the start of water flow to the start of measurement allows dissolved gas measurement to be performed in a short time.

[0034] Next, the installation direction of the dissolved gas measuring device 9 in the water treatment device 1 of this embodiment will be described in detail.

[0035] FIG. 8 is a schematic diagram illustrating an example of the installation angle range of dissolved gas measurement device 9. FIG. 8(a) shows a state in which the central axis of dissolved gas measurement device 9 is aligned with the vertical direction. FIG. 8(b) shows a state in which the central axis of dissolved gas measurement device 9 is tilted leftward with respect to the vertical direction. FIG. 8(c) shows a state in which the central axis of dissolved gas measurement device 9 is tilted rightward with respect to the vertical direction. Although not shown in FIGS. 8(a) to 8(c), supply hole 14 is located in the center, and discharge hole 15 is located at the right end as viewed in the drawings. Here, a state tilted leftward refers to a state in which the device is rotated counterclockwise so that discharge hole 15 is positioned higher than supply hole 14, and a state tilted right refers to a state in which the device is rotated clockwise so that supply hole 14 is positioned higher than discharge hole 15.

[0036] Dissolved gas measurement device 9 may be installed in any of the states shown in Figures 8(a) to 8(c), but is not limited to these. Dissolved gas measurement device 9 may be installed at any angle as long as the measurement target water supplied from supply hole 14 to chamber 10 flows upward through discharge hole 15 in a direction intersecting the horizontal direction.

[0037] When the dissolved gas measurement device 9 is installed in the state shown in Figure 8(a), the first surface 12 is approximately horizontal, and the discharge hole 15 and the supply hole 14 are positioned at approximately the same height in the vertical direction. In this case, air bubbles that have become mixed into the chamber 10 move toward the first surface 12 due to buoyancy, and then move toward the discharge hole 15 along the flow of the water to be measured. This allows the air bubbles to be discharged outside the chamber 10.

[0038] When the dissolved gas measurement device 9 is installed in the state shown in FIG. 8(b), the discharge hole 15 is positioned higher in the vertical direction than the supply hole 14. In this case, air bubbles mixed into the chamber 10 move toward the discharge hole 15 along the first surface 12 due to buoyancy, and also move toward the discharge hole 15 along the flow of the water to be measured. This allows the air bubbles to be discharged outside the chamber 10. Here, the angle θ1 that the central axis of the dissolved gas measurement device 9 makes with the vertical direction can be, for example, 90° or less.

[0039] When the dissolved gas measurement device 9 is installed in the state shown in FIG. 8(c), the discharge hole 15 is positioned lower than the supply hole 14 in the vertical direction. In this case, air bubbles mixed into the chamber 10 move toward the first surface 12 due to buoyancy and then move to the discharge hole 15 along the flow of the water to be measured. This allows the air bubbles to be discharged outside the chamber 10. Here, the angle θ2 between the central axis of the dissolved gas measurement device 9 and the vertical direction can be, for example, less than 90°. Note that in the state shown in FIG. 8(c), because the discharge hole 15 is positioned lower than the supply hole 14, it may be more difficult for the air bubbles to escape than in the states shown in FIGS. 8(a) and 8(b).

[0040] The installation direction of dissolved gas measuring device 9 can be determined with some degree of freedom in terms of the installation angle, taking into account the states of Figures 8(a) to 8(c) described above. From the perspective of ease of bubble removal, there is a relationship of [state of Figure 8(b)] > [state of Figure 8(a)] > [state of Figure 8(c)], so it is preferable to install dissolved gas measuring device 9 in the state of Figure 8(b) or the state of Figure 8(a).

[0041] In the water treatment device 1 of this embodiment, when the sensor unit 20 is removed from the chamber 10 for calibration or the like of the sensor unit 20, the water to be measured may leak from the chamber 10 and wet the cable 30. To prevent the cable 30 from getting wet, a mechanism (wet prevention mechanism) may be provided at the connection between the sensor unit 20 and the cable 30 to receive or absorb the water to be measured that leaks from the chamber 10 when the sensor unit 20 is attached or detached.

[0042] 9 is a schematic diagram showing an example of a wetting prevention mechanism, in which cross sections of each component are shown in schematic form, excluding a part of the dissolved gas measurement device 9.

[0043] As shown in FIG. 9, the wetting prevention mechanism 18 is provided at the connection between the sensor unit 20 and the cable 30. The wetting prevention mechanism 18 is made of a tray that catches the measurement target water that leaks from the chamber 10. The wetting prevention mechanism 18 has a through-hole in the center, and is fixed with the cable 30 passing through this through-hole. When the sensor unit 20 is removed, the wetting prevention mechanism 18 can catch the measurement target water that leaks from the chamber 10. This makes it possible to prevent the cable 30 from getting wet.

[0044] The wetting prevention mechanism 18 may have any structure as long as it can prevent the cable 30 from getting wet. For example, as the wetting prevention mechanism 18, an absorbent member such as a wipe may be provided at the connection portion between the sensor unit 20 and the cable 30.

[0045] The configuration of each part of the water treatment device 1 described above is an example, and appropriate changes or modifications can be applied as needed. For example, although an example of using a dissolved oxygen meter as an example of the dissolved gas measurement device 9 has been described, the present invention is not limited to this. Other dissolved gas meters, such as a dissolved carbon dioxide meter, may also be used as the dissolved gas measurement device 9. [Explanation of symbols]

[0046] 1 Water treatment equipment 9. Dissolved gas measuring device 10 chambers 11 Opening 12 First Side 13 Side 14 Supply hole 15 Discharge hole 16, 17 Piping attachment part 20 Sensor section 30 Cable

Claims

1. A water treatment device that treats water to be treated to produce treated water, A dissolved gas measurement device is provided which is configured to pass measurement target water which is a part of the water to be treated or a part of the treated water, the dissolved gas measuring device is provided with a supply hole and a discharge hole for passing the measurement target water, and the dissolved gas measuring device is installed so that the measurement target water supplied from the supply hole flows upward through the discharge hole in a direction intersecting the horizontal direction.

2. The dissolved gas measuring device is a chamber having an opening, the supply hole and the discharge hole being provided in a portion facing the opening; a sensor unit that is detachably attached to the opening of the chamber and measures a current value corresponding to the concentration of dissolved gas in the measurement target water that is passed through the sensor unit; a cable connected to a portion of the sensor unit on the side opposite to the chamber side, for transmitting a signal from the sensor unit; The water treatment device according to claim 1 , wherein the dissolved gas measurement device is installed so that the chamber is on the upper side and the cable is on the lower side.

3. 3. The water treatment device according to claim 2, wherein the supply hole is provided in a central portion of a first surface opposite the opening, the discharge hole is provided in a portion adjacent to the central portion of the first surface, and the dissolved gas measuring device is installed so that the first surface is horizontal or so that the discharge hole is positioned higher than the supply hole in the vertical direction, or so that the supply hole is positioned higher than the discharge hole.

4. The water treatment device according to claim 2 or 3, further comprising a mechanism at a connection between the sensor unit and the cable for receiving or absorbing the measurement target water leaking from the chamber when the sensor unit is attached or detached.

5. 1. A method for installing a dissolved gas measurement device for measuring the concentration of dissolved gas contained in measurement target water, comprising: a dissolved gas measurement device provided with a supply hole and a discharge hole for passing the water to be measured, and the dissolved gas measurement device is installed so that the water to be measured supplied from the supply hole flows upward through the discharge hole in a direction intersecting the horizontal direction.

6. A method for measuring a dissolved gas concentration in a water treatment device that treats water to be treated to produce treated water, the method comprising: attaching a dissolved gas measuring device configured to pass measurement target water, which is a part of the water to be treated or a part of the treated water, to the water treatment device; The dissolved gas measuring device is a chamber having an opening and a supply hole and a discharge hole for passing the water to be measured at a portion opposite the opening; a sensor unit that is detachably attached to the opening of the chamber and measures a current value corresponding to the concentration of dissolved gas in the measurement target water that is passed through the sensor unit; a cable for transmitting a signal from the sensor unit, the cable being connected to a portion of the sensor unit on the side opposite to the chamber side; a step of placing the dissolved gas measurement device with the chamber empty and the chamber on the upper side and the cable on the lower side; a step of supplying the measurement target water into the chamber through the supply hole and discharging it through the discharge hole; measuring the dissolved gas concentration using the sensor unit from the start of flow of the measurement target water.

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