Water quality measurement apparatus and method

Abstract

This water quality measurement apparatus includes: a plurality of measurement chambers each provided with a sensor; a test water supply means for supplying test water to each measurement chamber; a cleaning water supply means for supplying sensor cleaning water to each measurement chamber; and a control device for controlling the test water supply means and the cleaning water supply means such that when water quality is being measured using the sensor in one of the measurement chambers, control is performed in another measurement chamber . A water treatment device is provided with the water quality measurement device.

Description

Water quality measuring device and method

[0001] The present invention relates to an apparatus and method for measuring the quality of water such as wastewater.

[0002] When the quality of highly concentrated wastewater is continuously measured using a meter such as a pH meter, the accuracy of the measurement decreases if the meter, such as an electrode, becomes dirty.

[0003] Patent Documents 1 and 2 describe a treatment device that performs controlled injection of a pH adjuster based on the pH measurement value of high-concentration circulating waste paint water that contains paint. The device introduces wastewater into a measuring tank in which a pH electrode is installed, and performs measurement and control for a certain period of time once the water in the tank has been replaced with wastewater. Thereafter, clear water is introduced into the measuring tank to clean the pH electrode. Once the water in the measuring tank has been replaced with clear water, the introduction of clear water is stopped, and the pH electrode is left immersed in clear water while waiting until the next measurement process, thereby allowing measurements and pH control to be performed while the pH electrode is always kept clean.

[0004] Patent Document 3 describes a water quality measuring device equipped with a water quality sensor having a sensor body that comes into contact with the water to be measured, the water quality measuring device comprising a cover that surrounds the sensor body and forms a space between the sensor body and the cover, an opening in the cover that connects the space to the outside of the cover, a fresh water supply means that supplies fresh water to the space, an air supply means that supplies air to the space, a chemical solution supply means that supplies a cleaning chemical solution to the space, and an atmosphere communication means that connects the space to the atmosphere.

[0005] In the water quality measurement method of Patent Document 3, when measuring water quality, air is first supplied to the space. This causes fresh water to be discharged from the space. The air supply is then stopped, and the space is opened to the atmosphere. The measurement target water then flows into the space through the opening in the cover. The quality of the water in this space is then measured, thereby determining the quality of the measurement target water. After measurement is completed, air and fresh water are supplied to clean the sensor body with a gas-liquid multiphase flow. If the output characteristics of the sensor body deteriorate, a chemical solution is introduced into the space to perform chemical cleaning. When not measuring, the space between the sensor body and the cover is filled with fresh water.

[0006] JP 2016-140805 A JP 2017-202485 A JP 2022-26916 A

[0007] The water quality measurement devices and methods described in Patent Documents 1 to 3 include a cleaning process for sensors such as pH meters. This cleaning process does not involve measuring pH or controlling the pH based on the measurements. Therefore, while the devices and methods described in Patent Documents 1 to 3 are applicable to circulating water systems such as paint booth circulating water where the pH of the circulating water is averaged, when applied to measuring the quality of transient wastewater, continuous water quality measurement and control based on the measurement are not possible, making stable wastewater treatment impossible.

[0008] An object of the present invention is to provide an apparatus and method capable of continuously and accurately measuring the quality of wastewater or other water.

[0009] The gist of the present invention is as follows.

[0010] [1] A water quality measuring device having a plurality of measuring chambers each equipped with a sensor, a test water supply means for supplying test water to each measuring chamber, a cleaning water supply means for supplying cleaning water for the sensors to each measuring chamber, and a control device for controlling the test water supply means and the cleaning water supply means so that while water quality measurement is being performed by the sensors in some measuring chambers, cleaning is being performed in other measuring chambers.

[0011] [2] The water quality measuring device according to [1], wherein two measuring chambers are provided, and while water quality measurement is being carried out in one measuring chamber, cleaning of the sensor and subsequent standby are carried out in the other measuring chamber.

[0012] [3] The water quality measuring device of [2], wherein the test water supply means comprises a first pipe for supplying the test water, and a second pipe and a third pipe connected to the end of the first pipe via a three-way valve, the second pipe being connected to one of the measuring chambers, and the third pipe being connected to the other measuring chamber.

[0013] [4] The water quality measuring device of [2], wherein the sample water supply means comprises a first sample water pipe for supplying sample water to one measuring chamber and a second sample water pipe for supplying sample water to the other measuring chamber, the first sample water pipe being connected to the one measuring chamber and the second sample water pipe being connected to the other measuring chamber.

[0014] [5] The water quality measuring device according to [1], wherein the sensor is a pH meter.

[0015] [6] A water quality measurement method using the water quality measurement device according to any one of [1] to [5].

[0016] [7] A water treatment device having a treatment means for treating water to be treated, in which the water quality of the water to be treated is measured by a water quality measuring device and the treatment means is controlled based on the measurement results, wherein the water quality measuring device is any of the water quality measuring devices [1] to [5].

[0017] According to one aspect of the present invention, the water quality can be measured continuously and accurately even in the case of measuring the water quality of transient wastewater.

[0018] According to one aspect of the present invention, wastewater treatment can be carried out accurately based on this measurement value.

[0019] It is a schematic configuration diagram of a water quality measuring device according to a first embodiment. It is a timing chart explaining the operation of the water quality measuring device of Figure 1. It is a flow diagram of a wastewater treatment device. It is a graph showing measurement results in examples. It is a schematic configuration diagram of a water quality measuring device according to a second embodiment. It is a timing chart explaining the operation of the water quality measuring device of Figure 5.

[0020] Hereinafter, an embodiment will be described with reference to the drawings.

[0021] 1 is a schematic diagram of a water quality measuring device 10 according to an embodiment. This water quality measuring device does not soil the meters even when the wastewater is highly concentrated, and allows for continuous measurement and measurement control of the wastewater. Two identical meters and cleaning systems are provided, and these are operated alternately for the same wastewater, so that when one meter is measuring, the other meter is cleaned and on standby, allowing for continuous measurement and measurement control.

[0022] This water quality measuring device 10 divides the test water into a first system and a second system, and passes the water through them to measure the water quality.

[0023] The first system has a measurement tank (first measurement chamber) 1 and a sensor 2 installed in the measurement tank 1 (measurement chamber).

[0024] The second system has a measurement tank (second measurement chamber) 11 and a sensor 12 installed in the measurement tank 11 (measurement chamber).

[0025] As the sensor, various types of sensors can be used, such as a pH meter, a conductivity meter, a turbidity meter, an S.S. meter, and an ORP meter.

[0026] The sample water is introduced into the measuring tanks 1 and 11 via a pipe (first pipe) 3 , a three-way valve 4 , and a pipe (second pipe) 5 or a pipe (third pipe) 6 .

[0027] Clean cleaning water (e.g., tap water, pure water, ultrapure water, etc.) can be introduced into measurement tank 1 via piping 7 and valve 8, and cleaning water can be introduced into measurement tank 11 via piping 13 and valve 14.

[0028] The liquid can be discharged from the measuring tanks 1 and 11 via pipes 9 and 15 .

[0029] The three-way valve 4 and the valves 8 and 14 are switched between flow paths or opened and closed in response to signals from a controller (not shown).

[0030] FIG. 2 is a timing chart showing an example of the operation of the water quality measuring device 10 by this controller.

[0031] When water quality measurement is performed in the first system, three-way valve 4 connects pipes 3 and 5, and sample water is introduced into measuring tank 1, replacing the water in measuring tank 1 (time t1 to t2). Between times t2 and t3, water quality is measured by sensor 2. When time t3 is reached, three-way valve 4 is switched to allow the sample water to flow through the second system, and water quality measurement in the second system is initiated, as described below. During this time, a cleaning process is performed in the first system to clean the inside of measuring tank 1 and sensor 2. Specifically, valve 8 is opened, and cleaning water is circulated from pipe 7 into measuring tank 1 (time t3 to t4). When time t4 is reached, valve 8 is closed to terminate control, and this state is maintained until time t5, during which a standby process is performed (time t4 to t5).

[0032] In the second system, between times t1 and t6, the valve 14 is opened, and cleaning water is circulated through the pipe 13 into the measuring tank 11 to perform the cleaning process for the sensor 12. At time t6, the valve 14 is closed, and this state is maintained until time t3 to perform the standby process. At time t3, the test water is introduced and measured.

[0033] That is, in the second system, between times t1 and t6, valve 14 is opened to allow cleaning water to flow through measuring tank 11 to clean measuring tank 11 and sensor 12. At time t6, valve 14 is closed and maintained in this state until time t3, performing a standby step (times t6 to t3). Note that the length of time t1 to t6, i.e., the cleaning time for sensor 12 (t6-t1), is preferably the same as the cleaning time for sensor 2 (t4-t3).

[0034] At time t3, the three-way valve 4 is switched as described above to connect the pipes 3 and 6, and the test water is passed through the second measuring tank 11.

[0035] In this state, when time t7 arrives, the sample water continues to flow and measurement is performed by the sensor 12 (times t7 to t5). Note that the sample water replacement time for the second system (t7-t3) is preferably the same as the sample water replacement time for the first system (t2-t1).

[0036] After time t5 is reached, the same operations as those from time t1 to time t5 are repeated.

[0037] In this way, according to the water quality measurement method using the water quality measuring device 10, the water quality of the test water is always measured by the sensor except for the test water replacement time periods t1 to t2 and t3 to t7. Therefore, when the water treatment device is controlled based on the measurement results of the water quality measuring device 10, appropriate control of chemical injection, etc. can be performed.

[0038] FIG. 3 is a flow diagram showing an example of a wastewater treatment system that employs the water quality measuring device 10.

[0039] Wastewater is introduced from raw water tank 20 through screen 21 into reaction tank 22, where additives such as inorganic flocculant, powdered activated carbon, pH adjuster (NaOH, etc.) are added and the wastewater is stirred by a stirrer 22a.

[0040] The liquid in the reaction tank 22 is sent as test water to the water quality measuring device 10 via a sampling pump (not shown) and piping 3, and the water quality is measured. The addition of additives is controlled based on the results of this water quality measurement. The discharged water from the measuring tanks 1 and 11 is introduced into the reaction tank 22 via piping 9 and 15 and a junction piping 16.

[0041] The liquid in the reaction tank 22 is transferred to the coagulation tank 23, where a polymer coagulant is added and the liquid is stirred by the stirrer 23a, causing the coagulated flocs to grow.

[0042] The liquid in the coagulation tank 23 is introduced into a pressurized flotation tank 24, where it is subjected to a pressurized flotation treatment, and the flocs that float up are separated. The treated water is sent via a pipe 25 to the next process, such as a biological treatment process.

[0043] In the above embodiment, the supply of test water is switched by the three-way valve 4, but instead of the three-way valve, valves may be provided on the pipes 5 and 6, respectively.

[0044] 5 is a schematic diagram of a water quality measuring device 10A according to a second embodiment of the present invention, in which the same components as those in FIG. 1 are denoted by the same reference numerals.

[0045] In this embodiment, sample water is introduced into the measuring tank 1 in which the sensor 2 is installed through a pipe (first sample water pipe) 31 and a valve 32 consisting of an on-off valve.

[0046] Cleaning water can be introduced into the measuring tank 1 via a pipe 7 and a valve 8. A cleaning agent (cleaning agent-containing water) can be introduced into the measuring tank 1 via a pipe 35 and a pump 36.

[0047] The sample water is introduced into the measuring tank 11 in which the sensor 12 is installed via a pipe 33 and a valve 34 consisting of an on-off valve.

[0048] Cleaning water can be introduced into the measuring tank 11 via a pipe (second water test pipe) 13 and a valve 14. A cleaning agent (cleaning agent-containing water) can be introduced into the measuring tank 11 via a pipe 37 and a pump 38.

[0049] The liquid can be discharged from the measuring tanks 1 and 11 via pipes 9 and 15 .

[0050] The valves 8, 14, 32, 34 and the pumps 36, 38 are controlled to open and close and to be turned on and off by signals from a controller (not shown).

[0051] Figure 6 is a timing chart showing an example of operation of the water quality measuring device 10A by this controller. This water quality measuring device 10A is controlled with one cycle being 70 minutes. Figure 6 shows operation in the kth cycle and the (k+1)th cycle, where k is an integer equal to or greater than 1. Note that this 70 minutes is just an example and does not limit the present invention in any way.

[0052] When water quality measurement is performed in the first system, valve 32 is opened between times T1 and T2, and test water is introduced into measuring tank 1 to replace the water in measuring tank 1. That is, valve 32 is opened at time T1, and the water quality is measured by sensor 2 between times T2 and T7 without closing valve 32.

[0053] When time T7 is reached, valve 32 is closed and valve 8 is opened. Then, between times T7 and T8, valve 8 is opened, and cleaning water is introduced into measuring tank 1, pushing out the test water. When time T8 is reached, valve 8 is closed and pump 36 is turned on. Between times T8 and T9, pump 36 is turned on, and cleaning agent is introduced into measuring tank 1.

[0054] When time T9 is reached, the pump 36 is turned off, and this state is maintained until time T10, during which the inner surface of the measuring tank 1 and the sensor 2 are immersed and washed in the detergent-containing water.

[0055] When time T10 is reached, valve 8 is opened, cleaning water is introduced into measuring tank 1, and the waste cleaning liquid in measuring tank 1 is pushed out.

[0056] When the time T11 at which one cycle ends (time T1 of the next recycle) is reached, valve 8 is closed, and instead valve 32 is opened, and the process of the next cycle begins.

[0057] In this way, the test water is introduced into the measuring tank 1 between times T1 and T2, water quality measurements are made in the measuring tank 1 between times T2 and T7, and the measuring tank 1 is chemically cleaned and rinsed (the cleaning waste liquid is replaced with clean cleaning water) between times T7 and T11.

[0058] Between T1 and T11, the measuring tank 1 is subjected to measurement and cleaning (preparation for the next cycle) as described above, while between T1 and T11, the measuring tank 11 is subjected to preparation for and measurement of water quality measurement. That is, between times T1 and T2, the remainder of the water quality measurement process of the previous cycle is carried out in the measuring tank 11, but when this water quality measurement is completed at time T2, the valve 14 is opened. The valve 14 is then kept open until time T3, during which cleaning water is introduced into the measuring tank 11 and the test water is pushed out.

[0059] When time T3 is reached, valve 14 is closed. Also, pump 38 is turned ON to introduce the cleaning agent into measuring tank 11. When time T4 is reached, pump 38 is turned OFF, and this state is maintained until time T5, during which the inner surface of measuring tank 11 and sensor 12 are immersed and cleaned in the cleaning agent-containing water.

[0060] When time T5 is reached, valve 14 is opened, cleaning water is introduced into measuring tank 11, and the waste cleaning liquid in measuring tank 11 is pushed out. When time T6 is reached, valve 14 is closed. Valve 34 is also opened, and test water is introduced into measuring tank 11. When time T7 is reached, valve 34 is not closed, and water quality measurement by sensor 12 is initiated. This water quality measurement continues until time T2 of the next cycle.

[0061] This cycle is repeated thereafter, with the sensors 2 and 12 alternately measuring the water quality.

[0062] 5 and 6, water quality is measured continuously and without interruption, with sensor 2 measuring water quality from time T2 to T7, and sensor 12 measuring water quality from time T7 to the next cycle T2. Also, in this embodiment, while water quality is being measured with the sensor in one measuring tank, the other measuring tank and its sensor are cleaned with a detergent, so that deposits on the inner surface of the measuring tank and the sensor are sufficiently removed, allowing for highly accurate water quality measurement to be performed over a long period of time.

[0063] The above-described embodiments are merely examples of the present invention, and the present invention may be embodied in other forms.

[0064] In the present invention, three or more measuring tanks may be provided, and water quality measurements may be performed in some of the measuring tanks, while sensor cleaning or standby steps may be performed in the other measuring tanks.

[0065] In the above-described embodiments, the measuring tank 1, 11 is used, but a cover surrounding the sensor may be provided, as in Patent Document 2. In this case, an opening may be provided in the cover to allow the sample water to flow in and out of the space (measuring chamber) within the cover, or the sample water may be circulated through the space using a pump or the like. Furthermore, a cleaning water supply pipe and a cleaning agent supply pipe may be connected to supply cleaning water and a cleaning agent into the space to clean the sensor.

[0066] Two or more such covered sensors are installed, and while one or some of the sensors are performing the water quality measurement process, the other sensors are performing the cleaning process and standby process.

[0067] Example 1 Among the wastewater treatment tanks shown in the flow chart of FIG. 3, the raw water tank 20, the screen 21, and the reaction tank 22 were used to control the pH of wastewater from a metal processing factory.

[0068] The main conditions of this wastewater treatment facility are as follows:

[0069] Raw water flow rate (average): 300 L / min Reaction tank volume: 3000 L Volume of measurement tanks 1 and 11: 5 L Sensor: pH meter Sampling water (test water) flow rate: 10 L / min Cleaning water: industrial water Cleaning water supply rate during cleaning: 10 L / min Start and end times of each process: as shown in the leftmost column of Figure 2 Additive: 6N aqueous solution of NaOH

[0070] NaOH was added so that the pH detected by the sensors 2 and 12 (pH meters) would be 6.8 or less, and the addition of NaOH was stopped when the pH dropped to 6.5. The change in pH in the reaction tank 22 over time is shown in FIG.

[0071] Comparative Example 1 In Example 1, NaOH was added based solely on the detection value of sensor 2. That is, NaOH was added based on the detection value of sensor 2 between t2 and t3 in Figure 2, but no NaOH was added at other times. The change in pH in reaction tank 22 over time is shown in Figure 4.

[0072] As shown in FIG. 4, in Example 1, the pH is stably maintained at 6.5 to 6.8, but in Comparative Example 1, there are times when the pH falls significantly below 6.5.

[0073] Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications are possible within the scope of the invention. This application is based on Japanese Patent Application No. 2024-115006 filed on July 18, 2024, the entire contents of which are incorporated by reference.

[0074] 1, 11 Measuring tank 2, 12 Sensor 4 Three-way valve 8, 14, 32, 34 Valve 10, 10A Water quality measuring device 20 Raw water tank 21 Screen 22 Reaction tank 23 Coagulation tank 24 Pressurized flotation tank 36, 38 Pump

Claims

1. A water quality measuring device having a plurality of measuring chambers each equipped with a sensor, a test water supply means for supplying test water to each measuring chamber, a cleaning water supply means for supplying cleaning water for the sensors to each measuring chamber, and a control device for controlling the test water supply means and the cleaning water supply means so that while water quality measurement is being performed by the sensors in some measuring chambers, cleaning is being performed in other measuring chambers.

2. The water quality measuring device according to claim 1, wherein two measuring chambers are provided, and while water quality measurement is being carried out in one measuring chamber, sensor cleaning and subsequent standby are carried out in the other measuring chamber.

3. The water quality measuring device of claim 2, wherein the test water supply means comprises a first pipe for supplying test water, and a second pipe and a third pipe connected to the end of the first pipe via a three-way valve, the second pipe being connected to one of the measuring chambers and the third pipe being connected to the other measuring chamber.

4. The water quality measuring device of claim 2, wherein the sample water supply means comprises a first sample water pipe for supplying sample water to one measuring chamber and a second sample water pipe for supplying sample water to the other measuring chamber, the first sample water pipe being connected to the one measuring chamber and the second sample water pipe being connected to the other measuring chamber.

5. The water quality measuring device according to claim 1, wherein the sensor is a pH meter.

6. A water quality measuring method using the water quality measuring device according to any one of claims 1 to 5.

7. A water treatment device having a treatment means for treating water to be treated, wherein the water quality of the water to be treated is measured by a water quality measuring device and the treatment means is controlled based on the measurement results, wherein the water quality measuring device is any one of the water quality measuring devices of claims 1 to 5.

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