Water quality monitoring system, water treatment system, water quality monitoring device, and water quality estimation device

Abstract

To provide a technique that enables real-time measurement of T-N concentration at low cost.SOLUTION: A water quality monitoring system is provided, comprising an EC meter configured to measure electrical conductivity of monitoring target water, a communication interface configured to transmit data based on measurement by the EC meter to an external device via a communication link, and an estimation unit configured to estimate T-N concentration of the monitoring target water on the basis of the measurement result of the EC meter.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a technique for monitoring water quality, in particular, TN concentration. [Background technology]

[0002] In septic tanks (for example, see Patent Document 1 below), water quality such as turbidity, transparency (Tr), and BOD is measured during legal inspections and maintenance. These water qualities are measured by periodically taking samples of water on-site and analyzing them at a separate facility. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-117908 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned water quality measurement, there is a time lag between the collection of water and the acquisition of the measurement result of water quality, and even if the measurement result is undesirable, the judgment and response to improve it will be delayed. For this reason, a technology that can grasp water quality in real time is required. In addition, in areas where there is a total nitrogen quantity regulation or areas where the nitrogen concentration of treated water may affect the surrounding vegetation, there is a demand to grasp the TN concentration in real time. Although the TN concentration can be measured in real time on site by using an ammonia meter (typically an ion selective electrode type ammonia nitrogen measuring device), the introduction of an ammonia meter is not realistic because of high initial cost and running cost. For this reason, it is expected to provide a technology that can measure the TN concentration in real time at low cost. This problem is not limited to septic tanks, but is common to any water treatment facility. In addition, since many septic tanks that treat wastewater at the source are installed in a dispersed manner at sites separated from each other, it is hard work to test the water quality of each of such many septic tanks. [Means for solving the problem]

[0005] The present invention has been made to solve at least part of the above-mentioned problems, and can be realized, for example, in the following forms.

[0006] According to a first aspect of the present invention, there is provided a water quality monitoring system, comprising: an EC meter configured to measure the electrical conductivity of a target water, a communication interface configured to transmit data based on the measurement by the EC meter to an external device via communication; and an estimation unit configured to estimate a TN concentration of the target water based on the measurement result of the EC meter.

[0007] According to this water treatment system, the TN concentration can be measured (estimated) in real time using a low-cost EC meter by utilizing the correlation between electrical conductivity and TN concentration. Moreover, since the EC meter requires less maintenance work such as calibration compared to an ammonia meter, the running cost is also reduced compared to the case where the TN concentration is measured using an ammonia meter. Typically, the estimation unit is disposed in an external device, and the measurement value by the EC meter is transmitted to the external device via a communication interface, and the TN concentration is estimated in the external device. However, the communication interface may transmit the value of the TN concentration estimated by the estimation unit to the external device. Furthermore, according to this water treatment system, the TN concentration can be remotely monitored from a location away from the installation site of the water treatment equipment (e.g., a septic tank). Therefore, when it is desired to inspect or monitor the TN concentration of a large number of water treatment equipment, it is not necessary to inspect the TN concentration of each of the large number of water treatment equipment, and human labor is reduced.

[0008] According to the second aspect of the present invention, in the first aspect, the EC meter is configured to continuously measure electrical conductivity. The estimation unit is configured to continuously estimate the TN concentration based on the measurement results of the EC meter that are continuously measured. According to this aspect, by continuously monitoring the TN concentration, it is possible to easily grasp changes in the treatment state (e.g., information on when the water quality began to deteriorate) in a water treatment facility (e.g., a septic tank). In this specification, "continuously" means that continuous measurements are performed at a frequency that allows the fluctuation of the TN concentration within at least one month to be grasped (i.e., measurements are performed at least twice a month).

[0009] According to the third embodiment of the present invention, the water quality monitoring system in the second embodiment includes a notification unit that notifies a user when the estimated value of the TN concentration exceeds a reference value. According to this embodiment, when the estimated value of the TN concentration exceeds a reference value, the user can promptly take corrective measures. The "user" to be notified may be the installer of the water treatment facility, or may be the manager of an external device or the water treatment facility.

[0010] According to a fourth aspect of the present invention, in any one of the first to third aspects, the monitored water is at least one of water treated in a septic tank and water in the process of treatment. The estimation unit is configured to estimate the TN concentration based on a linear function having an X-intercept greater than zero, the X-axis being the EC value measured by the EC meter and the Y-axis being the TN concentration. The value of the X-intercept can be set as a unique value for each septic tank. According to this aspect, the TN concentration of at least one of water treated in a septic tank and water in the process of treatment can be accurately estimated by utilizing the correlation between the EC value and the TN concentration according to the installation environment of each septic tank.

[0011] According to a fifth aspect of the present invention, there is provided a water treatment system. This water treatment system includes the water quality monitoring system of the fourth aspect and a septic tank. The septic tank includes an anaerobic treatment unit and an aerobic treatment unit to remove at least TN, and is configured to perform water treatment using a biofilm method. In a septic tank using the biofilm method, microorganisms can be stably maintained, so nitrification is likely to proceed, and most of the nitrogen present in the monitored water is present in the form of ions, so the septic tank is compatible with the estimation of TN concentration based on the EC value, and the TN concentration can be estimated with high accuracy.

[0012] Compared to the activated sludge method, which uses suspended organisms, septic tanks that use the biofilm method are less susceptible to problems such as sludge outflow, making them easier to maintain. Specifically, septic tanks that use the biofilm method often use the "contact filter bed method," in which organisms are attached to fixed filter media, or the "carrier flow method," in which organisms are attached to a flowing carrier. Furthermore, in septic tanks that have fluctuating water levels within the tank, and in septic tanks that can return sludge by backwashing or circulation, measures have been taken to further reduce the risk of sludge outflow.

[0013] According to a sixth aspect of the present invention, there is provided a water quality monitoring device. The water quality monitoring device includes an EC meter configured to measure the electrical conductivity of monitored water, and a communication interface configured to transmit data based on the measurement by the EC meter to an external device via communication. According to this aspect, by combining with a seventh aspect described later, the same effect as that of the first aspect can be obtained.

[0014] According to a seventh aspect of the present invention, there is provided a water quality estimation device. The water quality estimation device includes a communication interface for receiving a measured value of the electrical conductivity of the water to be monitored, and an estimation unit configured to estimate the TN concentration of the water to be monitored based on the measured value. According to this aspect, by combining with the sixth aspect, the same effect as the first aspect can be obtained.

[0015] According to the eighth aspect of the present invention, in the seventh aspect, the water quality monitoring target water is at least one of water treated in a septic tank and water in the middle of treatment. The estimation unit is configured to estimate the TN concentration based on a linear function with the measured value on the X-axis and the TN concentration on the Y-axis, the linear function having an X-intercept greater than zero. According to this aspect, the same effect as the fourth aspect can be obtained.

[0016] The present invention is not limited to the above-mentioned aspects, but can be realized in any form, for example, as a water quality monitoring method, a water quality estimation program, or the like. [Brief description of the drawings]

[0017] [Figure 1] 1 is a schematic diagram showing a schematic configuration of a water treatment system according to one embodiment. [Diagram 2] FIG. 1 is a diagram showing a procedure for determining a linear function for estimating a TN concentration from an EC value. [Diagram 3] FIG. 1 is a diagram showing a procedure for determining a linear function for estimating a TN concentration from an EC value. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Fig. 1 is a schematic diagram showing a schematic configuration of a water treatment system 10 according to one embodiment. As shown in Fig. 1, the water treatment system 10 includes a septic tank 20 as an example of water treatment equipment, a water quality monitoring device 30, and a water quality estimation device 40. The water quality monitoring device 30 and the water quality estimation device 40 work together to function as a water quality monitoring system.

[0019] The septic tank 20 comprises a sedimentation tank 21, an anaerobic filter bed tank 22, a contact filter bed tank 23, a treated water tank 24, and a disinfection tank 25. The structure of a septic tank is well known, so its description will be brief here. Wastewater that flows into the septic tank 20 has suspended solids removed in the sedimentation tank 21, and is led to the anaerobic filter bed tank 22, the contact filter bed tank 23, and the treated water tank 24 in that order. The treated water led to the treated water tank 24 is returned to the sedimentation tank 21 as circulating water. A portion of the treated water stored in the treated water tank 24 is discharged via the disinfection tank 25.

[0020] Ammonia nitrogen in the form of ions (NH 4 In the contact filter bed tank 23, NOx-N is converted into NOx-N in the form of ions through a nitrification reaction caused by the action of nitrifying bacteria. When the water containing NOx-N is introduced into the anaerobic filter bed tank 22 via the treated water tank 24 and the sedimentation separation tank 21, the NOx-N is converted into gaseous N in the anaerobic filter bed tank 22 through a denitrification reaction caused by microorganisms. 2 Nitrogen in wastewater is removed by this nitrification / denitrification reaction.

[0021] The water treatment system 10 has a function of remotely monitoring the TN concentration (total nitrogen concentration) in the water treated in this way (from which nitrogen has been removed). Such a function will be described below. The water quality monitoring device 30 includes an EC meter 31 and a communication interface 32. The EC meter 31 is a general-purpose electrical conductivity measuring device and is installed in the treated water tank 24. However, the water to be measured by the EC meter 31 can be at least one of water treated in the septic tank 20 and water in the middle of treatment, and the EC meter 31 can be installed at any location as long as the measurement accuracy of the EC meter 31 is not hindered depending on what kind of measurement is desired and the structure of the septic tank. The measurement value (also called the EC value) measured for the water in the treated water tank 24 is input to the communication interface 32. The communication interface 32 transmits the input EC value to the water quality estimation device 40, which is an external device.

[0022] The water quality estimation device 40 is installed at a location (remote location) different from the installation site of the septic tank 20. The water quality estimation device 40 includes a CPU 41 and a communication interface 44. The communication interface 44 receives the EC value from the communication interface 32 by communicating with the communication interface 32 of the water quality monitoring device 30. The communication between the communication interface 32 and the communication interface 44 can be any form of wired communication, wireless communication, or a combination thereof. Typically, the communication between the communication interface 32 and the communication interface 44 is performed via the Internet.

[0023] In this embodiment, the water quality estimation device 40 is in the form of a personal computer. However, the water quality estimation device 40 can be modified into any form having the functions described below, and may be, for example, a cloud server. The CPU 41 also functions as an estimation unit 42 and a notification unit 43 by executing a predetermined program stored in the memory of the water quality estimation device 40.

[0024] The estimation unit 42 estimates the TN concentration based on the EC value received by the communication interface 44. Specifically, the estimation unit 42 estimates the TN concentration based on a linear function with the EC value as the X-axis (explanatory variable) and the TN concentration as the Y-axis (objective variable), the linear function having an X-intercept greater than zero. This linear function is pre-stored in the memory of the water quality estimation device 40. A method for setting the linear function will be described below.

[0025] First, the EC values ​​and TN concentrations are measured in large numbers by actual measurements for various wastewaters to be treated by a septic tank (this is not limited to the septic tank 20 to be monitored for water quality, but may be wastewater from any septic tank, or may be sample water prepared to resemble the water to be treated by a septic tank). FIG. 2 shows such measurement results plotted on an orthogonal coordinate system with the EC value on the X-axis and the TN concentration on the Y-axis. As is clear from FIG. 2, there is a strong correlation between the EC value and the TN concentration, which is expressed by a linear function. Next, a linear approximation equation is obtained from this plot. FIG. 2 shows a linear approximation equation 50 expressed by Y=aX+b.

[0026] Next, the EC value and TN concentration are measured for the wastewater in the septic tank 20, the water quality of which is to be monitored. This measurement needs to be done once. Next, the result of this single measurement is plotted on an orthogonal coordinate system, as shown by point 51 in FIG. 3. Then, a linear equation 52 (Y=aX+c) is determined that passes through point 51 and has the slope (a) of the linear approximation equation 50 shown in FIG. 2. This linear equation 52 is used as a linear function for estimating the TN concentration for the wastewater in the septic tank 20, the water quality of which is to be monitored.

[0027] Since septic tanks are installed independently in each home or business, the quality and amount of wastewater flowing into the tank varies depending on the installation location. The applicant of the present application has found that, despite such characteristics, there is a strong correlation between the EC value and the TN concentration in the wastewater to be treated by the septic tank, regardless of the conditions of the individual installation locations, and that the X-intercept of the linear function expressing this correlation is determined to be almost constant depending on the conditions of the individual installation locations. The X-intercept is determined by the concentrations of various ions (typically Na ions and Cl ions) that do not change due to wastewater treatment depending on the conditions of the individual installation locations. In this embodiment, by utilizing such characteristics, the TN concentration can be accurately estimated from the EC value using a linear function that is preset for each installation location of the septic tank.

[0028] When the TN concentration estimated by the estimation unit 42 exceeds a preset reference value, the notification unit 43 notifies the user of that fact. The user may be the installer of the septic tank 20, the manager of the water quality estimation device 40, or the person in charge of maintaining the septic tank 20. The notification may be performed in any manner, such as by sending an email to the user or by displaying a warning screen on a display connected to the water quality estimation device 40. With this configuration, when the TN concentration deteriorates, the user can quickly take remedial measures (for example, adjusting the air volume of the blower for aerating the contact filter bed tank 23, performing aerobic backwashing, venting anaerobic gas, adding methanol, etc.).

[0029] In this embodiment, the EC meter 31 continuously measures the electrical conductivity. The estimation unit 42 continuously estimates the TN concentration based on the continuously measured EC values. Therefore, the TN concentration can be continuously monitored to easily grasp the change in the treatment state in the septic tank 20. For example, as one aspect of "continuous", the electrical conductivity may be continuously measured every hour. In this way, the fluctuation of the TN concentration in a day can be grasped in detail. Alternatively, as one aspect of "continuous", the electrical conductivity may be continuously measured every 24 hours. In this way, the fluctuation of the TN concentration from day to day can be grasped in detail. The continuously measured EC value may be transmitted to the water quality estimation device 40 every time a measurement is performed, or the EC values ​​for a predetermined number of measurements may be transmitted to the water quality estimation device 40 all at once after a predetermined number of measurements are completed.

[0030] According to the above-described water treatment system 10, the correlation between the EC value (electrical conductivity) and the TN concentration is utilized to measure (estimate) the TN concentration in real time and to perform remote monitoring of the TN concentration using a low-cost general-purpose EC meter 31. Moreover, the EC meter 31 requires less maintenance work, such as calibration, than an ammonia meter, and therefore running costs are reduced compared to when the TN concentration is measured using an ammonia meter.

[0031] Moreover, according to the water treatment system 10, water treatment is performed in the septic tank 20 using a biofilm process (contact filter bed method in the above-mentioned embodiment). In a septic tank using the biofilm process, nitrification is likely to proceed and most of the nitrogen present in the water is present in the form of ions, so such a septic tank 20 is well suited to the estimation of the TN concentration based on the above-mentioned EC value, and the TN concentration can be estimated with high accuracy. Note that the biofilm process is not limited to the contact filter bed method, and may be a carrier flow method or the like.

[0032] Although the embodiment of the present invention has been described above, the above embodiment is for the purpose of facilitating understanding of the present invention and does not limit the present invention. The present invention may be modified or improved without departing from the spirit thereof, and the present invention includes equivalents thereof. In addition, any combination or omission of each component described in the claims and specification is possible within the scope of solving at least a part of the above-mentioned problems or achieving at least a part of the effects.

[0033] For example, at least some of the functions of the estimation unit 42 and the notification unit 43 may be included in the water quality monitoring device 30 instead of or in addition to the water quality estimation device 40.

[0034] Alternatively, the water quality estimation device 40 may collectively monitor the TN concentration for a plurality of septic tanks 20 installed in different locations.

[0035] Alternatively, the above-described embodiment is not limited to the septic tank 20, but can be applied to any water treatment facility that treats water containing nitrogen components. [Explanation of symbols]

[0036] 10...Water treatment system 20...Septic tank 21...Sedimentation tank 22...Anaerobic filter bed tank 23...Contact filter bed tank 24...Treatment tank 25...disinfection tank 30...Water quality monitoring device 32...Communication interface 40...Water quality estimation device 41...CPU 42...Estimation part 43...Information Department 44...Communication interface 50...first order approximation formula 51... points 52...linear expression

Claims

1. 1. A water quality monitoring system, comprising: an EC meter configured to measure the electrical conductivity of the monitored water; a communication interface configured to communicate data based on measurements by the EC meter to an external device; an estimation unit configured to estimate the T-N concentration of the monitoring target water based on the measurement result of the EC meter; A water quality monitoring system.

2. 2. The water quality monitoring system according to claim 1, The EC meter is configured to continuously measure the electrical conductivity; The estimation unit is configured to continuously estimate the T-N concentration based on the measurement results of the EC meter that are continuously measured. Water quality monitoring system.

3. 3. The water quality monitoring system according to claim 2, A notification unit is provided for notifying a user when the estimated value of the TN concentration exceeds a reference value. Water quality monitoring system.

4. The water quality monitoring system according to any one of claims 1 to 3, The monitored water is at least one of water treated in a septic tank and water in the process of being treated; The estimation unit is configured to estimate the T-N concentration based on a linear function having an X-intercept greater than zero, the X-axis representing the EC value measured by the EC meter and the Y-axis representing the T-N concentration. Water quality monitoring system.

5. 1. A water treatment system comprising: The water quality monitoring system according to claim 4; The septic tank and Equipped with The septic tank is provided with an anaerobic treatment section and an aerobic treatment section to remove T-N, and is configured to perform water treatment using at least a biofilm method. Water treatment system.

6. A water quality monitoring device, an EC meter configured to measure the electrical conductivity of the monitored water; a communication interface configured to transmit data based on measurements by the EC meter to an external device via communication; A water quality monitoring device comprising:

7. A water quality estimation device, a communication interface for receiving measured values ​​of electrical conductivity of the water to be monitored; an estimation unit configured to estimate the T-N concentration of the water to be monitored based on the measurement value; A water quality estimation device comprising:

8. The water quality estimation device according to claim 7, The water quality monitoring target water is at least one of water treated in a septic tank and water in the process of being treated, The estimation unit is configured to estimate the TN concentration based on a linear function having an X-intercept greater than zero, the linear function having an X-axis representing the measured value and a Y-axis representing the TN concentration. Water quality estimation device.

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