JP2002177945A - Water quality measuring system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water quality measuring system which is capable of automatically and surely subjecting the waste measuring liquid and waste cleaning liquid from a water quality measuring instrument to neutralization treatment. SOLUTION: The waste liquid treatment equipment transfers the neutralizing liquid stored in a chemical tank 3 by a pump 3 and continuously adds the neutralizing liquid to the waste measuring liquid of a specified amount and a nearly specified reagent concentration from the water quality measuring instrument 1 by a flow injection method. The equipment is provided with a regulating vessel and stirring machine for automatically add the neutralizing liquid of the amount and timing adequate according to the volume of the waste liquid, waste liquid period and the characteristics of the waste liquid from the water quality measuring instrument and further surely neutralizing and draining the waste liquid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water quality measurement system for monitoring water quality in a water purification treatment and a sewage treatment process with a water quality measurement instrument, and more particularly to a cleaning method using a measurement waste liquid and a chemical discharged from the water quality measurement instrument. The present invention relates to a waste liquid treatment device that adjusts a pH value of a discharged cleaning waste liquid.

[0002]

2. Description of the Related Art In recent years, there has been a concern that water quality may deteriorate in all environments, and water quality measuring instruments in water and sewer treatment processes for purifying such water have been diversified, sophisticated, and highly sensitive.

On the other hand, in these water quality measuring instruments, various substances are used as reaction reagents in order to improve measurement accuracy. In addition, the maintenance and management of water quality measuring instruments have been prolonged and costs have been reduced, and devices that automatically perform maintenance tasks such as cleaning by self-diagnosing the measuring instruments themselves are becoming mainstream.
Various cleaning agents are also used for cleaning the detection unit.

[0004]

[Problems to be solved by the invention] In order to achieve continuous development of companies in the era of great competition, it is now inevitable to build an environmental management system from social responsibility. Are regarded as important management issues. In addition, the government and local governments are studying ways to place environmental supervision and guidance at the core of administration. These companies and municipalities have established ISO standards in terms of environmental management.
Promoting acquisition of the 14000 series.

[0005] However, due to the detection of trace substances and the sophistication of measuring devices, the waste liquid discharged at the time of water quality measurement may exceed the standard value of waste water, and may hinder ISO certification.

In the water environment, monitoring of water quality for preserving lakes and rivers and monitoring of water quality in treatment processes such as water supply and sewerage are essential for improving or maintaining the environment. Some of the washing wastewater from the water quality measuring instrument and the measurement wastewater containing the reaction reagent may exceed the pH value (pH5 to 9) defined by the Sewerage Law.

[0007] For example, when measuring ammonia or the like by a water quality measuring device by the flow injection method, sodium hypochlorite is used as a reaction reagent, but hypochlorous acid has a high pH value (about pH 12) and is regulated by the Sewerage Law. Greatly exceeds the allowable range of pH 5-9.

In an optical water quality measuring instrument such as a turbidity meter or a UV meter, a sample water is caused to flow between a light source and a light receiving unit, and the water quality is measured from the attenuation of the light amount in the light receiving unit. Dirt on the optical surface of the light emitting and receiving part affects the measurement. Dilute hydrochloric acid or the like is often used to clean the measuring section in order to remove this stain. In this case, the cleaning waste liquid has a pH of about 2 and greatly deviates from the drainage standard value.

An object of the present invention is to provide a water quality measuring system capable of automatically and reliably neutralizing a measurement waste liquid and a washing waste liquid from a water quality measuring instrument.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides an appropriate amount, timing, and an appropriate neutralizing solution according to the amount of waste liquid, the period of waste liquid, and the nature of the waste liquid from a water quality measuring instrument. It is provided with an adjusting tank and a stirrer for automatically adding, and also for reliably neutralizing and draining the waste liquid, and has the following configuration.

(1) A water quality measuring system for adjusting the pH value of waste water by adding a neutralizing solution to a measurement wastewater measured by a water quality measuring device, wherein a neutralizing solution stored in a chemical solution tank is transferred by a pump, It is characterized by comprising a waste liquid treatment device for continuously adding a fixed amount of reagent from a water quality measuring device by a flow injection method to a measurement waste liquid having a substantially constant reagent concentration.

(2) A water quality measuring system for adjusting the pH value of waste water by adding a neutralizing solution to the washing waste liquid after water quality measurement by a water quality measuring device, wherein the neutralizing solution stored in the chemical tank is transferred by a pump. And a waste liquid treatment device for controlling the start and stop of the pump by a timer synchronized with the washing cycle of the water quality measuring device.

(3) A water quality measurement system for adjusting the pH value of waste water by adding a neutralizing solution to a measurement waste liquid or a washing waste liquid from a water quality measuring instrument that automates water quality measurement and washing after the measurement. The storage device further includes a waste liquid treatment device that transfers the stored neutralized solution by a pump and controls the start and stop of the pump in synchronization with a measurement operation or a cleaning operation of a water quality measuring device.

(4) A water quality measuring system for adjusting the pH value of waste water by adding a neutralizing solution to a measurement waste liquid or a washing waste liquid from a water quality measuring instrument, and storing the waste liquid from the water quality measuring instrument with a stirrer. Adjustable tank that can be stirred, neutralized liquid stored in the chemical solution tank is transferred by a pump, and the pH value of the drainage stored in the adjusting tank is measured with a pH meter, and when the measured value deviates from a preset upper and lower limit. The control unit includes a waste liquid treatment device that controls the activation of the pump.

(5) A water quality measuring system for adjusting the pH value of waste water by adding a neutralizing solution to a measurement waste liquid or a washing waste liquid from a water quality measuring instrument, and storing the waste liquid from the water quality measuring instrument with a stirrer. An adjusting tank that can be stirred, a neutralizing solution corresponding to the measurement waste liquid and a neutralizing solution corresponding to the washing waste liquid are stored in the respective chemical liquid tanks and transferred by the respective pumps, and the pH value of the drainage stored in the adjusting tank is adjusted to pH. And a controller configured to control the activation of one of the pumps according to the pH value when the measured value deviates from a preset upper and lower limit.

(6) A water quality measuring system for adjusting the pH value of waste water by adding a neutralizing solution to a measurement waste liquid or a washing waste liquid from a water quality measuring instrument, and storing the waste liquid from the water quality measuring instrument with a stirrer. A control tank that can be stirred and a neutralization liquid stored in the chemical liquid tank are transferred by a variable flow rate pump, and a control unit starts and controls the pump so as to add a neutralization liquid proportional to a drainage flow rate from the water quality measuring device. And a processing device.

(7) A water quality measuring system for adjusting the pH value of waste water by adding a neutralizing liquid to a measurement waste liquid or a washing waste liquid from a water quality measuring instrument for intermittently performing water quality measurement and washing after the measurement. A control tank that stores the waste liquid from the measuring instrument and can be stirred by the stirrer, and a pump that transfers the neutralizing liquid stored in the chemical tank by a pump and discharges the measurement waste liquid or cleaning waste liquid from the water quality measuring instrument. And a waste liquid treatment device that controls the pump to start and stop when the pH value of the stored drainage in the adjustment tank measured by a pH meter reaches a preset range. .

(8) A water quality measuring system for adjusting the pH value of waste water by adding a neutralizing solution to a measurement waste liquid or a washing waste liquid having a certain concentration from a water quality measuring instrument, and storing the waste liquid from the water quality measuring instrument. An adjustment tank that can be stirred by a stirrer, and a neutralizing solution stored in a chemical solution tank is transferred by a pump, and when the water level of the adjustment tank measured by a level meter reaches a certain level, the control unit starts and controls the pump. And a waste liquid treatment device for stopping and controlling the pump when a certain amount of neutralizing liquid is added.

(9) The control unit is characterized in that the stirrer is operated continuously or periodically, or is operated only for a period during which the neutralizing solution is added.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION In the structure of each embodiment described in detail below, components having the same functions are denoted by the same reference numerals, and the description thereof is omitted.

(Embodiment 1) The present embodiment is directed to a water quality measuring instrument using a measuring method such as a flow injection method in which a reaction reagent is constantly added to a sample water to be measured. This is suitable when the pH can be specified and the amount of drainage is constant.

In the flow injection method, a reaction reagent is added to a sample water to be measured, and the sample water and the reagent are allowed to react with each other while flowing through a thin tube. This is a measurement method that is measured by a luminescence method and expressed in terms of the concentration of a substance to be measured. In this measurement method, when detecting the target substance continuously,
The reaction reagent will be added continuously. Therefore, a constant amount of the measurement waste liquid is always discharged. In such a case, the concentration of the reaction reagent and the flow rate of the discharged reagent are almost constant, so that the neutralizing solution can be adjusted by the pH value and the flow rate of the waste solution.

FIG. 1 shows the configuration of the apparatus. In discharging the waste liquid from the water quality measuring device 1 by the flow injection method to a drain pipe, a waste liquid treatment device including a chemical liquid pump 2 and a tank 3 is provided. In this configuration, the neutralizing solution stored in the tank 3 is transferred by the chemical liquid pump 2 and the water quality measuring device 1
To the drain with the waste liquid from the drain. The chemical liquid pump 2 is a constant flow pump, and has a function of adjusting the flow rate and uses a material having high chemical resistance.

According to the present embodiment, since the concentration of the reaction reagent is substantially constant with a constant amount of the measurement waste liquid, the pH of the waste liquid is adjusted to an appropriate range by continuously adding a fixed amount of the neutralizing solution thereto. Can be maintained.

(Embodiment 2) This embodiment is suitable for a waste liquid treatment system when a cleaning liquid such as hydrochloric acid is used for cleaning the detection section of a water quality measuring instrument.

When an optical water quality measuring device is used for measuring water quality in the sewage treatment process, dirt caused by organic substances and the like adhering to optical surfaces (light emitting portion and light receiving portion) is remarkable.
Therefore, in order to prolong the maintenance cycle and secure the accuracy of the water quality measuring instrument, it is essential to periodically perform automatic chemical liquid cleaning in the flow path including the optical surface. Washing with hydrochloric acid is effective for removing adhering substances by organic substances.
It is necessary to treat the cleaning waste liquid because the water level falls below the wastewater standard value.

FIG. 2 shows a device configuration diagram of the present embodiment. The device configuration is a configuration in which a timer 11 is added to the configuration of the first embodiment. The timer 11 controls the operation cycle of the pump 2 and the operation time of the pump 2 so as to synchronize with the cleaning cycle of the water quality measuring device 1.

When the operation cycle set in the timer 11 is reached, a start signal is output from the timer 11 to the pump 2, and the operation of the pump 2 is started. The pump 2 pumps up the neutralized liquid in the tank 3 and drops it into the drain of the water quality measuring instrument 1. When the operation time set in advance in the timer 11 ends, a stop command is issued from the timer 11 to the pump 2, and the operation of the pump 2 ends.

According to this embodiment, since the water quality measuring device 1 is periodically cleaned, the neutralizing solution is added by the timer 11 synchronized with this period. This makes it possible to maintain the pH of the waste liquid in an appropriate range while eliminating wasteful consumption of the neutralized liquid.

(Embodiment 3) In recent years, the function of a water quality measuring instrument has been advanced, and the water quality measuring instrument itself automatically activates a diagnostic function of the apparatus, and the operating state and failure state of water quality measurement, contamination of a detecting section, and the like. It has been sophisticated to detect the degree of.

In such an apparatus, when the automatic measurement and the automatic cleaning of the detection unit are performed by self-diagnosis, the measurement and cleaning are performed irregularly due to a change in water quality or a change in water temperature. It is necessary to synchronize the devices.

FIG. 3 shows a configuration diagram of the present embodiment. This embodiment is different from the second embodiment in that the pump 2 is started and operated by a control signal from the water quality measuring instrument 1. The water quality measuring device 1 is provided with a function of outputting a signal for controlling the pump 2, and in the water quality measuring device 1, the cleaning of the detection unit is started, and at the same time, a start signal is output to the chemical liquid pump 2 of the waste liquid treatment device. Waste water treatment equipment is water quality measuring instrument 1
The operation of the pump 2 is started by a start signal from the water quality measuring instrument 1, and the pump 2 is stopped by a stop signal from the water quality measuring instrument 1.

According to the present embodiment, the neutralizing solution can be added at an appropriate timing in synchronization with the measurement by the water quality measuring device 1, and the neutralizing solution can be surely provided even when there is random or urgent water quality measurement. Can be added.

(Embodiment 4) This embodiment is suitable when the amount of measurement wastewater or washing wastewater discharged from a water quality measuring instrument is not specified.

FIG. 4 shows the device configuration of this embodiment. In the figure, the waste liquid treatment apparatus incorporates a control device 4 and a pH meter 5 in addition to the configuration of FIG. In addition, an adjustment tank 7 is provided,
The waste liquid from the water quality measuring device 1 is once discharged into the adjustment tank 7 and discharged into the drain pipe. The adjusting tank 7 is provided with a stirrer 6 for stirring the neutralized liquid dropped from the chemical liquid pump 2 with the waste liquid. p
The H meter 5 immerses its measuring terminal in the adjusting tank 7 and
Measure H.

In the above configuration, the wastewater treatment apparatus constantly measures the pH of the wastewater in the adjusting tank 7 with the pH meter 5, and the control unit 4, which takes in the measurement signal, operates when the pH value deviates from the preset upper and lower limits. Then, the chemical solution pump 2 is driven, and the addition of the neutralizing solution is continued until the pH falls within the set pH range. The drive of the stirrer 6 is appropriately changed, for example, continuously or periodically, or when the pH value suddenly changes.

According to the present embodiment, the waste liquid from the water quality measuring device 1 accumulates in the adjusting tank 7, and the pH value is constantly measured by the pH meter.
When the H value deviates from the preset upper and lower limits, the chemical solution pump 2 and the stirrer 6 are operated, and the neutralizing solution can be added until the pH value falls within the set range. More reliable than when draining into a drain pipe
The H value can be adjusted.

(Embodiment 5) This embodiment is suitable for the case where the pH of the measurement waste liquid and the cleaning waste liquid in the waste liquid from the water quality measuring instrument are different.

In the cleaning of a water quality measuring instrument, about 2% of dilute hydrochloric acid is often used as a cleaning agent because the adhesion of organic substances causes contamination. In addition, an alkaline reagent such as hypochlorous acid may be used as a reaction reagent in the measurement. In such a case, in order to treat both waste liquids, a corresponding neutralizing liquid is required.

FIG. 5 shows a configuration diagram of the present embodiment. In the present embodiment, in addition to the configuration of the fourth embodiment, the chemical liquid pump 2A
And one set of a chemical liquid tank 3A.

In this configuration, the waste liquid from the water quality measuring device 1 is stored in the adjusting tank 7 and the pH value is constantly measured by the pH meter 5,
The controller 4 activates the pump 2 and the stirrer 6 when the pH value exceeds a preset upper limit value, and adds the neutralizing solution until the pH value falls within the set range. The neutralizing solution in this case is an acidic reagent such as hydrochloric acid.

Similarly, when the pH value falls below the preset lower limit value, the pump 2A and the stirrer 6 are operated, and the neutralizing solution is added until the pH value falls within the set range.
In this case, an alkaline reagent such as sodium hydroxide is used as the neutralizing solution.

According to this embodiment, when both the measurement waste liquid and the cleaning waste liquid discharged from the water quality measuring device are discharged,
Neutralizing solutions suitable for the properties of each waste solution can be added individually.

(Embodiment 6) In the present embodiment, when the washing waste liquid and the measured waste water amount of a water quality measuring instrument fluctuate irregularly, the amount of the waste liquid is measured by a flow meter, and a neutralizing solution proportional to the measured value is added. I do.

FIG. 6 shows a configuration diagram of the present embodiment. In the same figure, the waste liquid flow rate of the water quality measuring instrument 1 is measured by a flow meter 8,
The data is captured by the control unit 4B. The controller 4B constantly monitors the flow rate value and sends a control signal to the chemical pump 2 so that a neutralizing solution proportional to the flow rate can be added. In this case, the chemical liquid pump 2 is of a type that can change the liquid flow rate. Also,
The stirrer 6 is operated at the same time as the operation of the chemical liquid pump 2 to stir the waste liquid in the adjusting tank 7 to make the waste liquid uniform.

According to the present embodiment, the amount of the neutralizing solution added to the adjusting tank 7 is adjusted according to the amount of the waste solution from the water quality measuring device 1. Therefore, even when the amount of the waste solution changes irregularly, the neutralizing solution can be used. Processing without excess or deficiency can be performed.

(Embodiment 7) In the present embodiment, when the water quality measuring device 1 intermittently performs the washing waste liquid or the measurement waste liquid, the waste liquid treatment apparatus is started in accordance with the timing of the waste liquid.

When the start-up signal is received from the water quality measuring device 1, the waste water treatment device operates the stirrer 6 and simultaneously sets the pH meter 5
The measurement of the pH value in the adjustment tank 7 is started with. The measurement signal measured by the pH meter 5 is taken into the control unit 4C of the waste liquid treatment apparatus, and the chemical liquid pump 2 is operated when the control unit deviates from a pH upper limit value or a lower limit value set in advance. The operation of the chemical pump 2 and the stirrer 6 is stopped when the pH of the drainage in the adjusting tank 7 reaches a range preset in the control unit 4C.

According to the present embodiment, even when the water quality measuring device 1 intermittently performs the washing waste liquid or the measurement waste liquid, the neutralizing solution can be supplied and the pH value can be adjusted only during that period, and the wasteful supply of the neutralizing solution can be performed. Can be eliminated.

(Embodiment 8) In this embodiment, the waste liquid treatment apparatus detects the water level in the adjustment tank, and adds a neutralizing solution corresponding to the capacity of the adjustment tank. However, the waste liquid concentration of the water quality measuring device 1 is always constant.

FIG. 8 shows the configuration of this embodiment. In the figure, the waste liquid treatment apparatus constantly monitors the water level of the adjusting tank 7 with a level meter 9, and from this monitoring signal, the control unit 4D operates the chemical liquid pump 2 when the water level reaches a preset level. At the same time, the stirrer 6 is operated to treat the waste liquid by adding a certain amount of neutralizing liquid to the measurement waste liquid stored in the adjusting tank 7. The pH value of the waste liquid is monitored by a pH meter 5, and when the pH reaches a permissible value set in advance in the control unit, the chemical pump 2 and the stirrer 6 are stopped, and the drain valve 10 is opened to drain.

According to the present embodiment, an appropriate neutralizing solution can be added when the drainage capacity of the adjustment tank reaches a constant value, and the frequency of waste liquid treatment (eg, pump operation) can be reduced.

[0053]

As described above, according to the present invention, an appropriate amount, timing, and an appropriate neutralizing solution are automatically added according to the amount of waste liquid from the water quality measuring device, the waste liquid period, and the properties of the waste liquid. The provision of the adjusting tank and the stirrer for reliably neutralizing and draining the waste liquid has the following effects.

(1) The measurement waste liquid and the washing waste liquid from the water quality measuring device can be neutralized automatically and reliably.

(2) Costs required for maintenance work such as recovery of waste liquid can be reduced.

(3) A water quality measuring device for discharging a plurality of types of waste liquids can also be used.

[Brief description of the drawings]

FIG. 1 is an apparatus configuration diagram according to a first embodiment of the present invention.

FIG. 2 is an apparatus configuration diagram according to a second embodiment of the present invention.

FIG. 3 is an apparatus configuration diagram according to a third embodiment of the present invention.

FIG. 4 is an apparatus configuration diagram according to a fourth embodiment of the present invention.

FIG. 5 is an apparatus configuration diagram according to a fifth embodiment of the present invention.

FIG. 6 is an apparatus configuration diagram according to a sixth embodiment of the present invention.

FIG. 7 is an apparatus configuration diagram according to a seventh embodiment of the present invention.

FIG. 8 is an apparatus configuration diagram according to an eighth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Water quality measuring device 2, 2A ... Chemical liquid pump 3, 3A ... Chemical liquid tank 4, 4A, 4B, 4C, 4D ... Control part 5 ... pH meter 6 ... Stirrer 7 ... Adjustment tank 8 ... Flow meter 9 ... Level meter 10 ... drain valve 11 ... timer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C02F 1/66 530 C02F 1/66 530K 530L 530Q G01N 33/18 106 G01N 33/18 106Z

Claims (9)

[Claims] 1. A water quality measurement system for adjusting the pH value of waste water by adding a neutralizing solution to a measurement waste solution whose water quality is measured by a water quality measuring device, wherein the neutralizing solution stored in a chemical solution tank is transferred by a pump,
A water quality measurement system comprising a waste liquid treatment device for continuously adding a fixed amount of reagent from a water quality measurement device by a flow injection method to a measurement waste liquid having a substantially constant reagent concentration. 2. A water quality measuring system for adjusting the pH value of waste water by adding a neutralizing solution to a washing waste solution after measuring water quality by a water quality measuring device, wherein the neutralizing solution stored in a chemical solution tank is transferred by a pump,
A water quality measuring system, comprising: a waste liquid treatment device that controls start and stop of the pump by a timer synchronized with a cleaning cycle of the water quality measuring device. 3. A water quality measurement system for adjusting a pH value of a waste water by adding a neutralizing solution to a measurement waste liquid or a washing waste liquid from a water quality measuring instrument that automates water quality measurement and washing after the measurement, and stores the pH value in a chemical solution tank. Pumped neutralizing solution,
A water quality measurement system, comprising: a waste liquid treatment device that starts and stops the pump in synchronization with a measurement operation or a cleaning operation of a water quality measurement device. 4. A water quality measuring system for adjusting the pH value of waste water by adding a neutralizing solution to a measurement waste liquid or a washing waste liquid from a water quality measuring instrument, wherein the waste liquid from the water quality measuring instrument is stored and stirred by a stirrer. Adjustable tank and neutralizer stored in chemical tank are transferred by pump.
The pH value of the wastewater stored in the adjusting tank is measured by a pH meter, and a wastewater treatment device is provided, wherein the control unit starts and controls the pump when the measured value deviates from a preset upper and lower limit. Water quality measurement system. 5. A water quality measuring system for adjusting the pH value of waste water by adding a neutralizing solution to a measurement waste liquid or a washing waste liquid from a water quality measuring instrument, wherein the waste liquid from the water quality measuring instrument is stored and stirred by a stirrer. A control tank capable of storing a neutralizing solution corresponding to the measurement waste liquid and a neutralizing solution corresponding to the cleaning waste liquid in their respective chemical liquid tanks and transported by the respective pumps. The pH value of the wastewater stored in the adjusting tank is measured by a pH meter. And a waste liquid treatment device for controlling the activation of one of the pumps according to the pH value when the measured value deviates from a preset upper and lower limit. 6. A water quality measuring system for adjusting the pH value of waste water by adding a neutralizing solution to a measurement waste liquid or a washing waste liquid from a water quality measuring instrument, wherein the waste liquid from the water quality measuring instrument is stored and stirred by a stirrer. A control tank capable of transferring the neutralized liquid stored in the chemical liquid tank by a variable flow rate pump, and the control unit starts and controls the pump so that the neutralized liquid is added in proportion to the drainage flow rate from the water quality measuring device. A water quality measurement system comprising a device. 7. A water quality measurement system for adjusting a pH value of a waste water by adding a neutralizing solution to a measurement waste liquid or a washing waste liquid from a water quality measuring device for intermittently performing water quality measurement and washing after the measurement, wherein the water quality measurement is performed. An adjustment tank that stores waste liquid from the vessel and can be stirred with a stirrer, and a neutralizing liquid stored in the chemical tank is transferred by a pump,
The control unit starts and controls the pump in accordance with the period of discharging the measurement waste liquid or the washing waste liquid of the water quality measuring instrument, and when the pH value of the stored drainage of the adjustment tank measured by the pH meter reaches a preset range. A water quality measurement system, comprising: a waste liquid treatment device for stopping and controlling the pump. 8. A water quality measuring system for adjusting the pH value of waste water by adding a neutralizing solution to a measurement waste liquid or a washing waste liquid of a certain concentration from a water quality measuring instrument, wherein the waste liquid from the water quality measuring instrument is stored and stirred. An adjustment tank that can be agitated by the machine and a neutralizing solution stored in the chemical solution tank are transferred by a pump,
A control unit that starts and controls the pump when the water level of the adjustment tank measured by a level meter reaches a certain level, and stops and controls the pump when a certain amount of neutralizing solution is added. A water quality measurement system comprising: 9. The control unit operates the stirrer continuously,
The water quality measurement system according to any one of claims 4 to 8, wherein the water quality measurement system is operated periodically or during a period during which the neutralizing solution is added.