Liquidity property determination system and liquidity determination method

Abstract

To provide a liquid property determination system that can easily determine a liquid property based on properties of exhaust gas discharged from a liquid, regardless of whether a sensor is disposed in the device or a gas separator is used, and further, can control a progress of wastewater treatment based on the determined liquid property.SOLUTION: There is provided a liquid property determination system including liquid containing means, gas supply means, carbon dioxide concentration measuring means, and liquid property determining means, in which the liquid property determining means is capable of determining a property of liquid contained in the liquid containing means by comparing a carbon dioxide concentration measured by the carbon dioxide concentration measuring means with an index carbon dioxide concentration.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a liquid property determination system and a liquid property determination method for determining the liquid property of a liquid. [Background technology]

[0002] In wastewater treatment, the properties (liquidity) of liquids, such as wastewater and treated water, affect the efficiency and progress of wastewater treatment. Therefore, various liquid-contact sensors are used to detect the liquid property. Typical examples of such sensors include dissolved oxygen sensors for detecting dissolved oxygen concentration, conductivity sensors for detecting conductivity, redox potential sensors for detecting redox potential, and pH sensors for detecting pH.

[0003] However, installing these liquid-contacting sensors in wastewater treatment equipment raises various problems. For example, installing them in an autonomous circulation-type water purification system increases the cost of the equipment because the sensors are expensive, the configuration of the equipment becomes complicated because sensors must be prepared according to the liquid property to be detected, and calibration after installation is limited. Therefore, to solve these problems, there is a need for a simple means for determining the liquid property of a liquid without using a sensor.

[0004] To achieve this, it is conceivable to determine the liquid properties based on the properties of the gas (exhaust gas) emitted from the liquid, rather than the liquid itself. For example, if a means for measuring the exhaust gas components is provided near the exhaust port of the water purification device, it is possible to prevent the structure of the main body that treats the wastewater in the water purification device from becoming complicated.

[0005] As a method for determining the liquid properties based on the properties of the gas discharged from such a liquid, there is known a method for operating a methane fermentation treatment device in which organic waste is decomposed in a fermentation tank by anaerobic organisms to produce biogas, the biogas discharged from the fermentation tank is desulfurized in a desulfurization tower, and then supplied to a biogas utilization facility, in which the carbon dioxide concentration of the gas obtained by desulfurizing the biogas in the desulfurizer is measured, and when the measured value increases or decreases above a predetermined concentration value, the treatment load in the fermentation tank is reduced or increased (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-81264 Summary of the Invention [Problem to be solved by the invention]

[0007] The method described in Patent Document 1 is a method for measuring the carbon dioxide concentration of gas obtained by desulfurizing biogas using a desulfurizer, and requires gas separation using a desulfurizer, which has the problem of making the equipment more complicated.

[0008] Therefore, the problem that the present invention aims to solve is to provide a liquid property determination system and a liquid property determination method that can easily determine the liquid property based on the properties of the exhaust gas discharged from the liquid, regardless of whether a sensor is placed within the device or whether a gas separator is used, and that can further control the progress of wastewater treatment based on the determined liquid property. [Means for solving the problem]

[0009] As a result of intensive research into solving the above-mentioned problems, the inventors have succeeded in creating a liquid property determination system and method, which solve the problems of the present invention, and which are based on a liquid storage means, a gas supply means, a carbon dioxide concentration measurement means, and a liquid property determination means. The present invention was completed based on this first successful example by the inventors.

[0010] That is, according to each aspect of the present invention, the following embodiments are provided. [1] A liquid determination system, The liquid property determination system includes a liquid storage means, a gas supply means, a carbon dioxide concentration measurement means, and a liquid property determination means, the liquid containing means is capable of containing a liquid and has an exhaust port; the gas supply means is capable of supplying gas into the liquid contained in the liquid containing means, The carbon dioxide concentration measuring means is capable of measuring the carbon dioxide concentration in the exhaust gas discharged from the exhaust port of the liquid containing means; and The liquid property determination system, wherein the liquid property determination means is capable of determining the property of the liquid contained in the liquid containing means by comparing the carbon dioxide concentration measured by the carbon dioxide concentration measurement means with an index carbon dioxide concentration. [2] The liquid property determination system according to [1], wherein the indicator carbon dioxide concentration is the carbon dioxide concentration of a liquid immediately after it has been contained in the liquid containing means and which has a pH of neutral, acidic, or alkaline. [3] The liquid property determination system according to [1] or [2], wherein the liquid storage means is a wastewater treatment tank, and the liquid is wastewater. [4] The liquid property determination system according to [3], wherein the wastewater treatment tank is a biological treatment tank. [5] A biological treatment determination system, [4] A liquid property determination system according to the present invention, and an organic substance supply means, the organic substance supplying means is capable of supplying an organic substance to the liquid contained in the liquid containing means; and The biological treatment determination system, wherein the carbon dioxide concentration is a carbon dioxide concentration measured after the organic matter is supplied. [6] The biological treatment determination system according to [5], wherein the organic matter is at least one organic matter selected from the group consisting of alcohols having 1 to 3 carbon atoms, monosaccharides, and disaccharides. [7] The biological treatment determination system according to [5], wherein the gas is selected from the group consisting of air, oxygen, ozone, and nitrogen. [8] The biological treatment determination system according to [5], wherein the liquid property determination means is further capable of determining the state of biological treatment of the liquid based on the determined liquid property of the liquid. [9] A biological treatment control system comprising: [8] The biological treatment determination system according to [8] is provided. The biological treatment control system, wherein the liquid property determining means is further capable of controlling the biological treatment of the liquid based on the determined state of biological treatment of the liquid.

[10] A method for determining liquidity, a measuring step of supplying gas to the liquid contained in the liquid containing means and measuring the carbon dioxide concentration in the exhaust gas discharged from the exhaust port of the liquid containing means; The liquid property determination method further comprises a determination step of comparing the measured carbon dioxide concentration with an index carbon dioxide concentration to determine the liquid property of the liquid.

[11] A method for determining biological treatment, a biodegradation step in which organic matter added to the biologically treated water contained in the biological treatment tank is biologically decomposed by consuming dissolved oxygen in the biologically treated water; a measuring step of supplying gas to the biologically treated water in which organic matter has been decomposed and measuring the carbon dioxide concentration in the exhaust gas discharged from the exhaust port of the biological treatment tank; The biological treatment determination method further comprises a determination step of comparing the measured carbon dioxide concentration with an index carbon dioxide concentration to determine the state of the biological treatment.

[12] The biological treatment determination method described in

[11] , wherein the determination step is a step of comparing the measured carbon dioxide concentration with an index carbon dioxide concentration to determine the pH of the biological treatment water, thereby determining the state of nitrification treatment and / or denitrification treatment.

[13] A biological treatment control method, comprising: a biodegradation step in which organic matter added to the biologically treated water contained in the biological treatment tank is biologically decomposed by consuming dissolved oxygen in the biologically treated water; a measuring step of supplying gas to the biologically treated water in which organic matter has been decomposed and measuring the carbon dioxide concentration in the exhaust gas discharged from the exhaust port of the biological treatment tank; a determining step of comparing the measured carbon dioxide concentration with an index carbon dioxide concentration to determine the pH of the biologically treated water, thereby determining the state of the nitrification treatment and / or denitrification treatment; a control step of controlling the biological treatment of the biologically treated water so that the pH of the biologically treated water is on the alkaline side, thereby continuing the nitrification reaction, and / or so that the pH of the biologically treated water is on the acidic side, thereby continuing the denitrification reaction; The biological treatment control method comprising: [Effects of the Invention]

[0011] According to the present invention, the liquid property of a liquid can be determined more easily by measuring the carbon dioxide concentration in the exhaust gas emitted from the liquid and then comparing the measured carbon dioxide concentration with a previously measured index carbon dioxide concentration.

[0012] According to the present invention, for example, the state of biological treatment, for example, the state of nitrification treatment and / or denitrification treatment, can be determined by measuring the carbon dioxide concentration in the exhaust gas discharged from the biologically treated water, and then comparing a measurement waveform created from the measured carbon dioxide concentration with an index waveform created by measuring the carbon dioxide concentration in the exhaust gas discharged from the wastewater before treatment. Furthermore, according to the present invention, the biological treatment can be easily controlled so that it is performed appropriately depending on the determined liquid property and state of biological treatment. [Brief explanation of the drawings]

[0013] [Figure 1]Figure 1 shows the results of continuous measurements of carbon dioxide concentration (CO2) and pH of treated water in a biological treatment tank while repeating a four-hour treatment cycle consisting of a one-hour anoxic stage and a three-hour nitrification stage. [Figure 2] Figure 2 shows the waveform of carbon dioxide concentration when the pH of the treated water is on the alkaline side (first pattern; A), when it is neutral (second pattern; B), and when it is on the acidic side (third pattern; C) in one treatment cycle of the anoxic stage and nitrification stage. [Figure 3] FIG. 3 is a schematic diagram showing the configuration of a liquid property determination system 1 according to one embodiment of the liquid property determination system. [Figure 4] FIG. 4 is a diagram showing a state in which the gas 21 is supplied to the liquid property determination system 1. As shown in FIG. [Figure 5] FIG. 5 is a block diagram showing the functional configuration of the liquid type determining means 40. [Figure 6] FIG. 6 is a flowchart showing a process for automatically determining the property of a liquid by the determining unit 411. [Figure 7] FIG. 7 is a flowchart showing the procedure for determining the liquid property by determining unit 411 when the liquid property is pH and the number of indicator waveforms is three. [Figure 8] FIG. 8 is a schematic diagram showing a biological treatment determination system 2 according to one embodiment of the biological treatment determination system. [Figure 9] FIG. 9 is a flowchart showing the procedure for determining the liquid property by the determining unit 411 in the biological treatment determining system 2. [Figure 10] FIG. 10 is a block diagram showing the functional configuration of a liquid property determining means 41 incorporated in the biological treatment control system. DETAILED DESCRIPTION OF THE INVENTION

[0014] Each aspect of the present invention will be described in detail below, but the present invention can take various forms as long as it achieves its object.

[0015] Unless otherwise specified, each term in this specification is used in the sense commonly used by those skilled in the art of water treatment and the like, and should not be construed as having an unduly limiting meaning. Furthermore, the speculations and theories made in this specification are based on the inventors' knowledge and experience to date, and therefore the present invention is not limited solely to such speculations and theories.

[0016] "Comprise," "contain," and "include" mean that elements other than those explicitly stated as included may be added (same meaning as "comprise at least"), but also encompass "consist of" and "essentially consist of." That is, "comprise" can mean including the explicitly stated elements and any one or more elements, consisting of the explicitly stated elements, or essentially consisting of the explicitly stated elements. "Have" is synonymous with "include." Elements include parts, means, ingredients, steps, conditions, parameters, and other limitations. "And / or" means any one or any or all combinations of two or more of the associated listed items. The "to" in a numerical range means a range that includes both the preceding and following numerical values, and also includes a range excluding one of the included limit values. For example, "0% to 100%" means 0% or more, 100% or less, or 0% or more and 100% or less.

[0017] Each aspect of the present invention will be described with reference to the drawings. In each drawing, elements that are less relevant to the present invention are omitted. Note that the direction indicated by the arrow UP (→UP) shown as appropriate in each drawing is the upward direction in the vertical direction.

[0018] [Summary of the Invention] The liquid property determination system includes, as its basic elements, a liquid storage means, a gas supply means, a carbon dioxide concentration measurement means, and a liquid property determination means. The liquid property determination system supplies gas from the gas supply means to the liquid stored in the liquid storage means, measures the carbon dioxide concentration in the gas (exhaust gas) discharged from the liquid, and compares the measured carbon dioxide concentration with an index carbon dioxide concentration to determine the liquid property, which is the property of the liquid.

[0019] Generally, nitrification and denitrification reactions occur in biological treatment tanks that biologically treat wastewater. That is, when the treated water in the biological treatment tank contains sufficient dissolved oxygen, for example by aerating it, aerobic nitrifying microorganisms oxidize the ammonia in the treated water to nitrate (nitrification reaction). Next, when the dissolved oxygen in the treated water decreases, anaerobic denitrifying microorganisms reductively convert the nitrate to nitrogen (denitrification reaction). Processes based on nitrification and denitrification, nitrification, and denitrification reactions are called nitrification and denitrification treatments, respectively.

[0020] In the nitrification reaction, alkaline ammonia is converted to acidic nitric acid, so the pH of treated water becomes acidic as the nitrification reaction progresses. In contrast, in the denitrification reaction, acidic nitric acid is converted to non-polar nitrogen, so the pH of treated water becomes neutral to alkaline as the denitrification reaction progresses.

[0021] The pH of ordinary domestic wastewater is between 7 and 10, which is on the neutral to alkaline side. The pH of such domestic wastewater, which is on the neutral to alkaline side, becomes acidic through nitrification treatment, and then becomes neutral to alkaline through denitrification treatment.

[0022] Therefore, in nitrification treatment, even if the dissolved oxygen concentration of household wastewater is sufficient, if the pH of the treated water is on the alkaline side, it indicates that the nitrification reaction has not progressed sufficiently.In contrast, in this case, if the pH of the treated water is on the acidic side, it indicates that the nitrification reaction has progressed sufficiently.In this way, if the dissolved oxygen concentration of household wastewater is sufficient, the progress of the nitrification treatment can be determined by using the pH of the treated water as an indicator.

[0023] On the other hand, in denitrification treatment, if the dissolved oxygen concentration of the treated water after nitrification treatment is sufficiently reduced, the pH of the treated water being on the acidic side indicates that the denitrification treatment has not progressed sufficiently. In contrast, in this case, if the pH of the treated water is on the neutral to alkaline side, it indicates that the denitrification reaction has progressed sufficiently. In this way, if the dissolved oxygen concentration of the treated water after nitrification treatment is sufficiently reduced, the progress of the denitrification treatment can be determined by using the pH of the treated water as an indicator.

[0024] The present inventors have investigated various methods for monitoring the pH of treated water. To simulate the biological treatment of domestic wastewater, urea, a simulated wastewater, was added to a biological treatment tank and aerated. The carbon dioxide concentration in the gas discharged from the exhaust port of the biological treatment tank immediately after aeration was very high, but decreased over time. Carbon dioxide exists in two forms: one that was dissolved in the anaerobic conditions before aeration began, and another that was generated by the decomposition of urea by heterotrophic bacteria. Furthermore, ammonia produced by the hydrolysis of urea is oxidized by nitrifying bacteria to produce nitric acid, lowering the pH. Next, a readily decomposable organic substance, such as a lower alcohol such as ethanol, is added to the domestic wastewater in the biological treatment tank as a hydrogen donor. By maintaining an anaerobic condition without aeration, denitrifying bacteria reduce nitrate to produce nitrogen gas (the anoxic or denitrifying stage). At this stage, the carbon dioxide concentration in the exhaust gas discharged from the exhaust port of the biological treatment tank is very low, and it is believed that the carbon dioxide generated by the decomposition of readily decomposable organic matter by microorganisms is dissolved in the treated water. In this stage, the pH also rises as nitrate levels decrease. Next, a nitrification stage was carried out by adding urea to the biological treatment tank and aerating it, followed by an anoxic stage. The nitrification and anoxic stages were then repeated alternately.

[0025] By conducting such experiments, the inventors discovered that the measurement waveform obtained by continuously plotting the carbon dioxide concentration measured in the nitrification stage has a specific pattern for each pH range of the treated water. That is, when the pH of the treated water in the biological treatment tank is on the alkaline, neutral, or acidic side, the measured carbon dioxide concentration waveform shows a different pattern (Figures 1 and 2).

[0026] Figure 1 shows the results of continuous measurements of carbon dioxide concentration (CO2) and pH of treated water in a biological treatment tank while repeating a four-hour treatment cycle consisting of a one-hour anoxic stage and a three-hour nitrification stage. Figure 2 also shows the waveforms of carbon dioxide concentration when the pH of the treated water is alkaline (first pattern; A), neutral (second pattern; B), and acidic (third pattern; C) during one treatment cycle of the anoxic and nitrification stages.

[0027] As shown in Figures 1 and 2A, when the pH of the treated water in the biological treatment tank is on the alkaline side, the carbon dioxide concentration waveform shows a broader (wider, lower) peak and a pattern in which the carbon dioxide concentration gradually decreases over time. This is thought to be because if nitrification is insufficient during the repeated nitrification-denitrification cycle, a large amount of ammonia remains in the treated water, causing the pH to rise and making it difficult for the dissolved carbon dioxide to be discharged, resulting in a gradual release.

[0028] In contrast, when the pH of the treated water was on the acidic side (Figure 2C), the carbon dioxide concentration waveform showed a pattern in which the peak became sharper (narrower and higher) and the carbon dioxide concentration rapidly decreased as the pH decreased. This is presumably because, if denitrification is insufficient during the repeated nitrification-denitrification cycle, a large amount of nitrate remains in the treated water, lowering the pH and allowing the dissolved carbon dioxide to be easily and instantaneously released.

[0029] Therefore, by comparing the measured waveform obtained by measuring the carbon dioxide concentration in the exhaust gas discharged from the biological treatment tank with the indicator waveform of carbon dioxide concentration, which serves as an indicator, obtained by measuring wastewater whose pH (alkaline, neutral, or acidic) is known in advance immediately after flowing into the biological treatment tank, the pH of the treated water in the biological treatment tank can be determined as a liquid, and the degree of progress of the nitrification and denitrification processes can be determined based on this.

[0030] Furthermore, in the biological treatment tank during the denitrification stage, aeration with nitrogen gas instead of air allows for forced discharge of dissolved carbon dioxide while maintaining an anoxic state. This allows for the measurement waveform of carbon dioxide concentration to be obtained, which is patterned for each pH of the treated water. Therefore, by obtaining an index waveform of the index carbon dioxide concentration in the same way, it is possible to determine the pH of the treated water in the biological treatment tank as a liquid, and thereby the progress of the denitrification treatment.

[0031] The various aspects of the present invention, including the liquid property determination system and liquid property determination method of one embodiment of the present invention, were created based on the findings discovered for the first time by the inventors as described above.

[0032] [Liquidity determination system] A liquid property determination system according to one aspect of the present invention includes a liquid containing means, a gas supplying means, a carbon dioxide concentration measuring means, and a liquid property determining means.

[0033] Examples of liquids whose liquid properties can be determined by the liquid property determination system include, but are not limited to, wastewater such as domestic wastewater discharged from toilets, kitchens, bathrooms, washing machines, etc., urban wastewater, commercial wastewater, agricultural wastewater, and industrial wastewater, as well as sewage, rainwater, surface water, well water, and tap water. Wastewater can also be referred to as treated water or water to be treated in a water treatment system. The liquid may also contain solid matter such as pulverized matter.

[0034] The liquid property may be anything that characterizes the properties of the liquid, such as properties that can be measured by contacting the detection part with the liquid using a sensor. Preferred properties are pH, oxidation-reduction potential, and conductivity, with pH being more preferred.

[0035] The liquid property determination system is used to determine the property of a liquid. By using the liquid property determination system, the property of a liquid can be known quantitatively, such as numerically or within a certain range, or qualitatively, using a relative scale (high, low, alkaline, neutral, acidic, etc.). The liquid property determination system may be equipped with a warning means for issuing a warning to notify users that the determined liquid property is not within a predetermined range.

[0036] The liquid property determination system can be used as a water treatment system or incorporated into a water treatment system to determine the state of water treatment according to the determined liquid property. For example, when the liquid property determination system is incorporated into a biological treatment determination system to determine pH as the liquid property, the progress of biological treatment, such as nitrification and denitrification, can be determined depending on whether the determined pH of the liquid is on the alkaline, neutral, or acidic side.

[0037] Furthermore, in this case, depending on the determined degree of progress of biological treatment, it becomes possible to perform manual or automatic control to ensure smooth biological treatment by adding operations to improve the progress of biological treatment. A liquid pH determination system that enables such control is also called a liquid pH control system. In this way, depending on the application, the liquid pH determination system can take the form of a biological treatment determination system and a biological treatment control system.

[0038] A specific embodiment of the liquid property determination system will be described with reference to FIG. The liquid property determination system 1 includes a liquid storage means 10, a gas supply means 20, a carbon dioxide concentration measurement means 30, and a liquid property determination means 40. For convenience, FIG. 3 illustrates a liquid 11 stored in the liquid storage means 10, an exhaust pipe 50 extending from an exhaust port 12 of the liquid storage means 10, and a valve 51 for opening and closing the exhaust pipe 50. In FIG. 3, the valve 51 is in a closed state. The carbon dioxide concentration measurement means 30 is disposed on the exhaust pipe 50. However, the exhaust pipe 50 may be branched, so that a portion of the exhaust from the exhaust pipe 50 may flow into the carbon dioxide concentration measurement means 30, or all of it may flow into the carbon dioxide concentration measurement means 30. Furthermore, branching the exhaust pipe 50 in this manner can prevent condensation and reduce measurement errors. For this purpose, a humidity removal means may be provided between the exhaust port 12 and the carbon dioxide concentration measurement means 30. The valve 51 is not required.

[0039] Liquid containing means 10 is configured to be capable of containing liquid 11 and to have an exhaust port 12. Exhaust gas discharged from liquid containing means 10 is, in principle, discharged to the outside of liquid containing means 10 through exhaust port 12. Liquid containing means 10 is preferably sealed so that exhaust gas is discharged through exhaust port 12. Liquid containing means 10 may have an inlet for receiving liquid from outside the system, or an outlet for sending liquid to the outside of the system.

[0040] The liquid storage means 10 may be called a water tank when the liquid 11 is water, or a wastewater treatment tank when the liquid 11 is wastewater. Furthermore, the liquid storage means 10 may be called a biological treatment tank when the liquid 11 is used for biological treatment.

[0041] When the liquid storage means 10 is a biological treatment tank, it uses organisms such as microorganisms to treat the liquid 11. The microorganisms may be aerobic microorganisms, anaerobic microorganisms, or a combination of these. The liquid storage means 10 may hold a mixture of aerobic and / or anaerobic microorganisms, may have both an aerobic area and an anaerobic area, or may be a multi-tank with separate aerobic and anaerobic tanks. When the liquid storage means 10 is a multi-tank, it can be structured to have two or more tanks by providing a partition such as a permeable membrane that allows water to pass through but not microorganisms.

[0042] The gas supply means 20 is configured to be able to supply gas into the liquid 11 contained in the liquid containing means 10. Figure 4 illustrates a state in which the gas 21 is being supplied into the liquid 11 by the gas supply means 20. In Figure 4, the valve 51 is in an open state. As the gas supply means 20 supplies the gas 21 into the liquid 11, the gas within the liquid containing means 10 is exhausted to the outside of the liquid containing means 10 through the exhaust port 12 and the exhaust pipe 50.

[0043] The gas 21 supplied from the gas supply means 20 may be any gas other than a gas with a carbon dioxide concentration, and is appropriately selected depending on the contents of the liquid 11. Examples of the gas 21 include air, oxygen, ozone, nitrogen, and argon. Specifically, when the liquid 11 is a liquid to be subjected to a nitrification treatment, the gas 21 is preferably air or oxygen. The gas supply means 20 may be, for example, a blower, a gas cylinder, or the like, capable of supplying these gases.

[0044] The carbon dioxide concentration measuring means 30 is configured to be able to measure the carbon dioxide concentration in the exhaust gas discharged from the exhaust port 12 of the liquid containing means 10. The carbon dioxide concentration measuring means 30 is disposed on an exhaust pipe 50 extending from the exhaust port 12. The carbon dioxide concentration measuring means 30 may also be disposed inside the exhaust pipe 50.

[0045] The carbon dioxide concentration measuring means 30 may be any means capable of measuring the carbon dioxide concentration in gas, and may also be called a carbon dioxide sensor, CO2 sensor, etc. The carbon dioxide concentration can be measured, for example, based on the amount of infrared light absorbed by carbon dioxide. The portion of the exhaust pipe 50 where the carbon dioxide concentration measuring means 30 is located is called the carbon dioxide measuring unit 501. The carbon dioxide concentration measuring means 30 measures the carbon dioxide concentration in the exhaust gas passing through the carbon dioxide measuring unit 501 and outputs the result as a numerical value (units such as ppm or %).

[0046] The carbon dioxide concentration measuring means 30 can also be placed directly on the exhaust port 12, rather than on the exhaust pipe 50. However, it is preferable that the carbon dioxide concentration measuring means 30 is not wetted by the liquid 11, so that the detection unit (sensor) and circuitry are not damaged and the measurement accuracy is not reduced.

[0047] The liquid property determining means 40 is configured to be able to determine the property of the liquid 11 by comparing the carbon dioxide concentration measured by the carbon dioxide concentration measuring means 30 with an index carbon dioxide concentration.

[0048] Fig. 5 is a block diagram showing the functional configuration of the liquid property determination means 40. As illustrated in Fig. 5, the liquid property determination means 40 comprises a processing unit 410, a storage unit 420, and an input / output unit 430. The liquid property determination means 40 may further comprise a display unit. Each component is connected to each other via a bus 440 so as to be able to communicate with each other.

[0049] The liquid property determination means 40 may be, for example, a microcontroller, a single-board computer, a personal computer (notebook PC, desktop PC), a tablet terminal, a smartphone, or the like.

[0050] The processing unit 410 is configured to be able to acquire the carbon dioxide concentration, which is the value detected by the carbon dioxide concentration measuring means 30.

[0051] The input / output unit 430 is configured to be able to transmit the detected value of the carbon dioxide concentration measuring means 30 to the processing unit 410 .

[0052] The memory unit 420 is configured with a storage device and stores at least a determination program 421 and an index value 422 that is an indicator carbon dioxide concentration. The memory unit 420 may store the detected value of the carbon dioxide concentration measuring means 30, an output value that is the determination result from the determination unit 411, etc. The determination program 421 functions to cause the determination unit 411 to determine the liquid property of the liquid 11 based on the detected value of the carbon dioxide concentration measuring means 30 and the index value 422.

[0053] The determination unit 411 is configured to be able to acquire the carbon dioxide concentration, which is the value detected by the carbon dioxide concentration measurement means 30. The determination unit 411 determines the liquid properties of the liquid 11 by comparing the carbon dioxide concentration, which is the value detected by the carbon dioxide concentration measurement means 30 (also referred to as the measured carbon dioxide concentration), with the index value 422.

[0054] The measured carbon dioxide concentration is compared with an index carbon dioxide concentration measured under the same conditions, such as time and operation. The comparison preferably involves comparing a measurement waveform created from continuous data of the measured carbon dioxide concentration with an index waveform created from continuous data of the index carbon dioxide concentration. The liquid type determination means 40 preferably outputs the measurement waveform, or both the measurement waveform and the index waveform. The comparison of the measurement waveform with the index waveform may be performed automatically by the determination unit 411 using AI (artificial intelligence) or the like based on the peak width, the tendency of the rate of change, the magnitude of the integrated value of the waveform over a predetermined time, etc., or may be performed manually by visual inspection based on the output waveform.

[0055] Fig. 6 shows a flowchart for causing the determination unit 411 to determine the liquid property based on a comparison between the measurement waveform and the index waveform. Fig. 6 is a flowchart for when the liquid property is pH and the index waveform indicates that the pH of the liquid is on the acidic side.

[0056] As illustrated in FIG. 6, the determination unit 411 acquires continuous data of the carbon dioxide concentration in the exhaust gas from the liquid 11 from the carbon dioxide concentration measurement means 30 (S101). Next, a waveform pattern is created from the acquired continuous data of the carbon dioxide concentration to form a measured waveform (S102). Next, the measured waveform is compared with an index value 422, which is a pre-created index waveform stored in the memory unit 420 (S103). If the measured waveform and the index waveform are identical or similar, it is determined that the pH of the liquid 11 is on the acidic side (S104). On the other hand, if the measured waveform and the index waveform are not identical or similar, it is determined that the pH of the liquid is not on the acidic side (S105).

[0057] The index waveform is created based on the carbon dioxide concentration measured at the time when the liquid property of the liquid 11 is known. In this case, the liquid 11 is presumed to be on the alkaline side.

[0058] The number of index waveforms may be one or more than two, for example, one, two, three, four, five, six, seven, eight, or nine.

[0059] 7 shows a flowchart of the liquid property determination performed by the determination unit 411 when the liquid has various pH values ​​and three index waveforms. The index waveforms are as follows: Pattern 1 is created using the carbon dioxide concentration when the liquid has an alkaline pH; Pattern 2 is created using the carbon dioxide concentration when the liquid has a neutral pH; and Pattern 3 is created using the carbon dioxide concentration when the liquid has an acidic pH. The index waveforms of Patterns 1 to 3 are, for example, as illustrated in FIGS. 2A to 2C.

[0060] 7, the determination unit 411 acquires continuous data of the carbon dioxide concentration in the exhaust gas from the liquid 11 from the carbon dioxide concentration measurement means 30 (S201), and creates a measurement waveform from the acquired continuous data of the carbon dioxide concentration (S202). Next, the determination unit 411 compares the measured waveform pattern with index waveform patterns 1 to 3 stored in the memory unit 420 (S203). If the measured waveform and index waveform pattern 1 are identical or similar, it determines that the pH of the liquid is on the alkaline side (S204). If the measured waveform and index waveform pattern 2 are identical or similar, it determines that the pH of the liquid is near neutral (S205). Alternatively, if the measured waveform and index waveform pattern 3 are identical or similar, it determines that the pH of the liquid is on the acidic side (S206).

[0061] The liquid property determination system may include other components in addition to the liquid containing means, the gas supply means, the carbon dioxide concentration measuring means, and the liquid property determination means, such as an exhaust pipe 50 and a valve 51 as illustrated in Figures 3 and 4.

[0062] The exhaust pipe 50 is not particularly limited in material, diameter, length, etc., as long as it is capable of transferring the exhaust from the liquid storage means 10 to the carbon dioxide concentration measurement means 30, and may or may not be branched.

[0063] The valve 51 may be, for example, a diaphragm valve, a ball valve, or a solenoid valve, but is preferably a solenoid valve so that its opening and closing and its degree of opening can be electronically controlled. The liquid property determination system 1 preferably includes a control means for controlling the valve 51.

[0064] The liquid property determination system may include various sensors in the liquid containing means, such as, but not limited to, a temperature sensor, a conductivity sensor, a dissolved oxygen sensor, and a pH sensor.

[0065] [Biological treatment determination system] A specific embodiment of the liquid property determination system is a biological treatment determination system in which the liquid storage means is a biological treatment tank. The biological treatment determination system preferably further comprises an organic matter supply means in addition to the components of the liquid property determination system.

[0066] A biological treatment determination system 2, which is a specific embodiment of the biological treatment determination system, will be described with reference to Fig. 8. In Fig. 8, components common to the liquid property determination system 1 in Figs. 3 and 4 are denoted by the same reference numerals. However, the liquid storage means 10 should be read as the biological treatment tank 10, and the liquid 11 should be read as the treated water 11. Furthermore, the treated water 11 contains microorganisms for biological treatment.

[0067] The biological treatment determination system 2 includes an organic matter supply means 60. The organic matter supply means 60 is configured to be able to supply organic matter to the treated water 11 in the biological treatment tank 10. The organic matter supply means 60 supplies the organic matter to the biological treatment tank 10 using a pump 61. However, the organic matter supply means 60 may also supply the organic matter by free fall. When supplying the organic matter by free fall, a valve such as a solenoid valve may be used instead of the pump 61 to adjust the supply rate, or these may not be used at all.

[0068] Organic matter that serves as a hydrogen donor serves as a nutrient source for denitrifying bacteria. If the amount of organic matter that serves as a hydrogen donor in the wastewater is insufficient, any organic matter that can be easily assimilated (decomposed) by microorganisms, i.e., easily decomposable organic matter, may be added. For example, it is preferable to add organic matter with a relatively low molecular weight, such as alcohols with 1 to 3 carbon atoms, such as methanol or ethanol, or sugars, such as monosaccharides and disaccharides.

[0069] The method of determining the liquid property by the biological treatment determination system 2 will be described with reference to Fig. 9. Fig. 9 is a flowchart showing the liquid property determination by the determination unit 411 in the biological treatment determination system 2.

[0070] Organic matter is supplied to the biological treatment tank 10 by the organic matter supply means 60 (S301). Next, the organic matter is assimilated by microorganisms in the treated water 11 in the biological treatment tank 10, sufficiently reducing the dissolved oxygen in the treated water 11 and creating an anoxic state (S302). The time for creating an anoxic state may be set appropriately depending on the type and amount of organic matter dissolved in the treated water 11, the type and amount of microorganisms, etc., but is, for example, several minutes to several tens of hours, and preferably 30 minutes to 2 hours. The reduction in dissolved oxygen can be confirmed when the carbon dioxide concentration measured by the carbon dioxide concentration measurement means 30 is barely detected.

[0071] Next, gas 21 is supplied to the treated water 11 in the biological treatment tank 10 by gas supply means 20 (S303). The gas 21 supplied at this time is preferably air or oxygen for nitrifying microorganisms. The time for supplying gas 21 may be appropriately set depending on the expected liquidity of the treated water 11, the type and amount of organic matter in the treated water 11, the type and amount of microorganisms, etc., but may be, for example, several tens of minutes to several tens of hours, and preferably 2 to 5 hours.

[0072] When supplying the gas 21, the organic matter such as urea may be supplied by the organic matter supply means 60, or may be supplied by providing a separate organic matter supply means.

[0073] Next, the carbon dioxide concentration of the exhaust gas discharged from the biological treatment tank 10 is measured using the carbon dioxide concentration measuring means 30 and the liquid property determining means 40, and the measured waveform of the carbon dioxide concentration is compared with the index waveform to determine the liquid property of the treated water 11 (S304). The liquid property determination is illustrated in, for example, Figures 6 and 7.

[0074] The index waveform is obtained by adding easily decomposable organic matter to the wastewater immediately after it enters the biological treatment tank 10, maintaining an anoxic state, starting aeration, and measuring the carbon dioxide concentration over a predetermined period of time, in the same manner as the measurement waveform. The index waveform can be the one obtained when the wastewater is neutral. Similarly, index waveforms when the liquid is alkaline, neutral, or acidic can be created by calibration using water samples taken after operation has started.

[0075] For example, a measurement waveform and an index waveform are created for a four-hour cycle consisting of one hour of anoxic conditions and three hours of aeration. The waveform obtained in this way shows a peak in carbon dioxide concentration at the start of aeration. As the nitrification reaction progresses, the nitrate concentration increases and the pH decreases, the carbon dioxide concentration peak becomes sharper (narrower and higher). On the other hand, as the denitrification reaction progresses, the nitrate concentration decreases and the pH increases, the carbon dioxide concentration peak becomes broader (wider and lower).

[0076] In the biological treatment determination system 2, the liquid property determination means 40 is preferably configured to be further capable of determining the state of nitrification treatment or denitrification treatment of the treated water 11 based on the determined liquid property of the treated water 11.

[0077] [Biological treatment control system] Another specific embodiment of the liquid property determination system is a biological treatment control system that controls the treatment water in a biological treatment tank so that it is biologically treated appropriately.

[0078] In the biological treatment control system, the liquid property determining means is configured to determine the liquid property of the treated water and also to be able to control the biological treatment of the treated water based on the determined state of biological treatment of the treated water.

[0079] The biological treatment control system may have a configuration similar to that of the biological treatment determination system. However, the biological treatment control system is configured to be able to control the biological treatment. Control of the biological treatment in the biological treatment control system may be achieved by adding a function to the liquid property determination means, or by using a biological treatment control means different from the liquid property determination means. However, to simplify the configuration of the biological treatment control system, it is preferable that the liquid property determination means also have a biological treatment control function.

[0080] A specific example of a liquid property determination means 41 that also has a biological treatment control function will be described with reference to Figure 10. In Figure 10, components that are common to the liquid property determination means 40 in Figure 5 are assigned the same reference numerals.

[0081] 10 is a block diagram showing the functional configuration of the liquid property determining means 41. As illustrated in FIG.

[0082] The control unit 412 is configured to be able to acquire the determination information of the determination unit 411, and to control other components of the biological treatment determination system, such as the gas supply means 20 and the organic matter supply means 60, based on the determination information.

[0083] In the liquid property determination means 41, the input / output unit 430 is further configured to be able to transmit the output value from the control unit 412 to the gas supply means 20 and the organic substance supply means 60. The memory unit 420 may further store the output value, which is the control result from the control unit 412, etc.

[0084] The control unit 412 controls other components such as the gas supply means 20 and the organic matter supply means 60 based on the determination information acquired from the determination unit 411 .

[0085] For example, when the treatment water 11 is being subjected to nitrification treatment, the control unit 412, which has obtained determination information from the determination unit 411 that the pH of the treatment water 11 is on the neutral to alkaline side, controls the gas supply means 20 to continue supplying air or oxygen from the gas supply means 20 to the biological treatment tank 10 so that the nitrification treatment continues. On the other hand, when the control unit 412 has obtained determination information from the determination unit 411 that the pH of the treatment water 11 is on the acidic side, it controls the gas supply means 20 to stop supplying air or oxygen from the gas supply means 20 to the biological treatment tank 10 so that the nitrification treatment ends.

[0086] When the treated water 11 is being subjected to denitrification treatment, the control unit 412, which has obtained determination information from the determination unit 411 that the liquid pH of the treated water 11 is on the acidic side, stops the supply of air or oxygen from the gas supply means 20 to the biological treatment tank 10 to control the continuation of the denitrification treatment.

[0087] [System application] According to the liquid type determination system, biological treatment determination system, and biological treatment control system of one embodiment of the present invention, the liquid type of the liquid can be determined based on the carbon dioxide concentration in the exhaust gas, the state of biological treatment of the liquid can be determined, and the biological treatment can be controlled so that it is carried out appropriately. Because these systems can be simply configured, they can be applied to, for example, autonomous circulation type water purification devices.

[0088] Generally, self-sustaining water purification systems are divided into two main types: those for toilet wastewater from household wastewater, and those for other types of grey water (shower wastewater, laundry wastewater, kitchen wastewater, etc.). When these systems use biological treatment, it is desirable to monitor that the pH of the wastewater being treated remains near neutral, as this not only monitors the nitrification / denitrification process (nitrification reduces the pH by converting ammonia to nitrate under aerobic conditions (with aeration), while denitrification increases the pH by removing nitrate as nitrogen gas under anaerobic conditions), but also allows for monitoring for the inflow of unexpected acids or alkalis caused by the user. However, pH sensors are wetted, expensive, and have durability issues, making them unrealistic for use in self-sustaining water purification systems.

[0089] Therefore, if it were possible to use a non-wetted, inexpensive, and durable CO2 sensor to determine the pH of wastewater during treatment, it would be possible to monitor that the pH of wastewater during treatment remains near neutral, even in an autonomous circulation water purification system.

[0090] In addition to pH, the CO2 peak waveform can also be affected by factors such as the size of the liquid storage means, the amount of gas supplied, the size of bubbles generated by the gas supply, and the level (concentration) of microbial activity. However, these generally do not change over a short period of time, so if an index waveform is obtained in advance, pH fluctuations can be detected from the CO2 peak waveform from the measured waveform. If ammonia is excessive and the pH is high, nitrification can be promoted by stopping the inflow of wastewater such as human waste into the device and extending the aerobic state. If nitrate is excessive and the pH is low, the anoxic period can be extended to promote denitrification, and the amount of easily decomposable organic matter added can be increased to further strengthen the anoxic state.

[0091] Therefore, a specific preferred embodiment of the liquid property determination system, biological treatment determination system, and biological treatment control system according to one aspect of the present invention is an autonomous circulation-type water purification device incorporating these systems.

[0092] [Another aspect of the present invention] Another aspect of the present invention is a liquid property determination method realized by the liquid property determination system of one aspect of the present invention, etc. The liquid property determination method includes, for example, a measurement step of supplying gas to the liquid contained in a liquid containing means and measuring the carbon dioxide concentration in the exhaust gas discharged from an exhaust port of the liquid containing means, and a determination step of comparing the measured carbon dioxide concentration with an index carbon dioxide concentration to determine the liquid property of the liquid.

[0093] Another aspect of the present invention is a biological treatment determination method realized by the biological treatment determination system or the like of one aspect of the present invention. The biological treatment determination method includes, for example, a biodegradation step in which organic matter added to biologically treated water contained in a biological treatment tank is biologically decomposed by consuming dissolved oxygen in the biological treatment water, a measurement step in which gas is supplied to the biologically treated water in which the organic matter has been decomposed and the carbon dioxide concentration in the exhaust gas discharged from an exhaust port of the biological treatment tank is measured, and a determination step in which the measured carbon dioxide concentration is compared with an index carbon dioxide concentration to determine the state of biological treatment. Preferably, the determination step is a determination step in which the measured carbon dioxide concentration is compared with the index carbon dioxide concentration to determine the pH of the biologically treated water, thereby determining the state of nitrification treatment, denitrification treatment, or both.

[0094] Another aspect of the present invention is a biological treatment control method realized by the biological treatment control system or the like of one aspect of the present invention. The biological treatment control method includes, for example, a biodegradation step of biologically decomposing organic matter added to biologically treated water contained in a biological treatment tank by consuming dissolved oxygen in the biological treatment water, a measurement step of supplying gas to the biologically treated water in which the organic matter has been decomposed and measuring the carbon dioxide concentration in the exhaust gas discharged from an exhaust port of the biological treatment tank, a determination step of comparing the measured carbon dioxide concentration with an index carbon dioxide concentration to determine the pH of the biologically treated water and thereby determine the state of nitrification treatment and / or denitrification treatment, and a control step of controlling the biological treatment of the biologically treated water so that the pH of the biologically treated water is alkaline and thereby the nitrification reaction continues, and / or so that the pH of the biologically treated water is acidic and thereby the denitrification reaction continues. [Industrial Applicability]

[0095] The liquid property determination system, biological treatment determination system, and biological treatment control system of one embodiment of the present invention are simply configured and can determine the liquid property or biological treatment state based on the carbon dioxide concentration in the exhaust gas, and can also control the biological treatment to ensure that it is carried out appropriately.Therefore, they can be used, for example, in an autonomous circulation type water purification system that employs biological treatment. [Explanation of symbols]

[0096] 1. Liquid Judgment System 2. Biological treatment assessment system 10 Liquid storage means (biological treatment tank) 11 Liquid (treated water) 12 Exhaust port 20 Gas supply means 21 Gas 30 Carbon dioxide concentration measurement means 40 Liquidity determination means 401 Processing section 411 Judgment section 412 Control Unit 420 Storage section 421 Judgment Program 422 index value 430 Input / output section 440 Bus 50 exhaust pipe 501 Carbon dioxide measurement unit 51 Valve 60 Organic matter supply means 61 Pump

Claims

1. A liquid determination system, comprising: The liquid property determination system includes a liquid storage means, a gas supply means, a carbon dioxide concentration measurement means, and a liquid property determination means, the liquid containing means is capable of containing a liquid and has an exhaust port; the gas supply means is capable of supplying gas into the liquid contained in the liquid containing means, The carbon dioxide concentration measuring means is capable of measuring the carbon dioxide concentration in the exhaust gas discharged from the exhaust port of the liquid containing means; and The liquid property determination system, wherein the liquid property determination means is capable of determining the property of the liquid contained in the liquid containing means by comparing the carbon dioxide concentration measured by the carbon dioxide concentration measurement means with an index carbon dioxide concentration.

2. 2. The liquid property determination system according to claim 1, wherein the indicator carbon dioxide concentration is the carbon dioxide concentration of a liquid immediately after it has been contained in the liquid containing means and which has a neutral, acidic, or alkaline pH.

3. 3. The liquid property determination system according to claim 1, wherein the liquid storage means is a wastewater treatment tank, and the liquid is wastewater.

4. The liquid property determination system according to claim 3 , wherein the wastewater treatment tank is a biological treatment tank.

5. A biological treatment determination system, A liquid property determination system according to claim 4 and an organic matter supply means, the organic substance supplying means is capable of supplying an organic substance to the liquid contained in the liquid containing means; and The biological treatment determination system, wherein the carbon dioxide concentration is a carbon dioxide concentration measured after the organic matter is supplied.

6. The biological treatment determination system according to claim 5, wherein the organic matter is at least one organic matter selected from the group consisting of alcohols having 1 to 3 carbon atoms, monosaccharides, and disaccharides.

7. The biological treatment determination system according to claim 5 , wherein the gas is selected from the group consisting of air, oxygen, ozone, and nitrogen.

8. The biological treatment determination system according to claim 5 , wherein the liquid property determination means is further capable of determining a state of biological treatment of the liquid based on the determined liquid property of the liquid.

9. 1. A biological treatment control system comprising: The biological treatment determination system according to claim 8 is provided, The biological treatment control system, wherein the liquid property determining means is further capable of controlling the biological treatment of the liquid based on the determined state of biological treatment of the liquid.

10. A method for determining liquidity, comprising: a measuring step of supplying gas to the liquid contained in the liquid containing means and measuring the carbon dioxide concentration in the exhaust gas discharged from the exhaust port of the liquid containing means; The liquid property determination method further comprises a determination step of comparing the measured carbon dioxide concentration with an index carbon dioxide concentration to determine the liquid property of the liquid.

11. A biological treatment determination method, comprising: a biodegradation step in which organic matter added to the biologically treated water contained in the biological treatment tank is biologically decomposed by consuming dissolved oxygen in the biologically treated water; a measuring step of supplying gas to the biologically treated water in which organic matter has been decomposed and measuring the carbon dioxide concentration in the exhaust gas discharged from the exhaust port of the biological treatment tank; The biological treatment determination method further comprises a determination step of comparing the measured carbon dioxide concentration with an index carbon dioxide concentration to determine the state of the biological treatment.

12. The biological treatment determination method according to claim 11, wherein the determination step is a step of comparing the measured carbon dioxide concentration with an index carbon dioxide concentration to determine the pH of the biological treatment water, thereby determining the state of nitrification treatment and / or denitrification treatment.

13. 1. A biological treatment control method comprising: a biodegradation step in which organic matter added to the biologically treated water contained in the biological treatment tank is biologically decomposed by consuming dissolved oxygen in the biologically treated water; a measuring step of supplying gas to the biologically treated water in which organic matter has been decomposed and measuring the carbon dioxide concentration in the exhaust gas discharged from the exhaust port of the biological treatment tank; a determining step of comparing the measured carbon dioxide concentration with an index carbon dioxide concentration to determine the pH of the biologically treated water, thereby determining the state of nitrification treatment and / or denitrification treatment; a control step of controlling the biological treatment of the biologically treated water so that the pH of the biologically treated water is on the alkaline side, thereby continuing the nitrification reaction, and / or so that the pH of the biologically treated water is on the acidic side, thereby continuing the denitrification reaction; The biological treatment control method comprising:

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