Liquidity determination system and liquidity determination method

Abstract

The object of the present invention is to provide a liquid property determination system that can easily determine the liquid property based on the properties of the exhaust gas discharged from the liquid, regardless of the placement of a sensor within the device and the use of a gas separator, and can further control the progress of wastewater treatment based on the determined liquid property. [Solution] The above-mentioned object is achieved by a liquid property determination system comprising a liquid storage means, a gas supply means, a carbon dioxide concentration measuring means, and a liquid property determination means, the liquid property determination means being capable of determining the liquid property of the liquid stored in the liquid storage means by comparing the carbon dioxide concentration measured by the carbon dioxide concentration measuring means with an index carbon dioxide concentration.

Description

[Technical field]

[0001] The present invention relates to a liquid property determination system and a liquid property determination method for determining the 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-contacting sensors are used to detect the liquid properties. Representative examples of such sensors include dissolved oxygen sensors for detecting dissolved oxygen concentration, electrical conductivity sensors for detecting electrical conductivity, redox potential sensors for detecting redox potential, and pH sensors for detecting pH.

[0003] However, when these liquid-contacting sensors are installed in wastewater treatment equipment, various problems arise. For example, when installing them in an autonomous circulation type water purification equipment, problems arise such as the equipment becoming expensive because the sensors are expensive, the configuration of the equipment becoming complicated because sensors are prepared according to the liquid property to be detected, and restrictions on calibration after installation. Therefore, in order to solve these problems, it is required to determine the liquid property of the liquid by a simple means without using a sensor.

[0004] In order to achieve this, it is conceivable to determine the liquid properties based on the properties of the gas (exhaust gas) discharged from the liquid, rather than the liquid itself. For example, by providing a means for measuring the exhaust gas components 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 the biogas is supplied to a biogas utilization facility, in which the carbon dioxide concentration of the gas obtained by desulfurizing the biogas in a desulfurizer is measured, and when the measured value increases or decreases above a predetermined concentration value, processing load control is performed to reduce or increase the processing load in the fermentation tank (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2005-81264 A 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 the placement of a sensor within the device and the use of a gas separator, and 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 problems, the inventors have succeeded in creating a liquid property determination system and a liquid property determination method, which are based on a liquid storage means, a gas supply means, a carbon dioxide concentration measurement means, and a liquid property determination means, in order to solve the problems of the present invention. The present invention has been completed based on the first successful example achieved by the inventors.

[0010] That is, according to each aspect of the present invention, the following embodiments are provided. [1] A liquid chemistry 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 a carbon dioxide concentration in the exhaust gas discharged from an exhaust port of the liquid storage 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 measuring means with an index carbon dioxide concentration. [2] The liquid property determination system described in [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 has a pH that is 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 comprising: [4] A liquid property determination system according to the present invention, and an organic matter supplying means, The organic matter supplying means is capable of supplying an organic matter 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 the present invention is provided. The biological treatment control system, wherein the liquid property determining means is further capable of controlling 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 a gas to the liquid contained in the liquid containing means and measuring a carbon dioxide concentration in exhaust gas discharged from an 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, comprising: a biodegradation process in which organic matter added to the biologically treated water contained in the biological treatment tank is biologically decomposed by consuming the 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 an 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 the steps of: a biodegradation process in which organic matter added to the biologically treated water contained in the biological treatment tank is biologically decomposed by consuming the 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 an exhaust port of the biological treatment tank; A determination step of collating 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; 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 allowing the nitrification reaction to continue, and / or so that the pH of the biologically treated water is on the acidic side, thereby allowing the denitrification reaction to continue; The biological treatment control method comprising the steps of: Effect of the Invention

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

[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 biological treatment 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 the biological treatment. [Brief description of the drawings]

[0013] [Figure 1]FIG. 1 shows the results of continuous measurements of carbon dioxide concentration (CO2) and pH of the treated water in the biological treatment tank while repeating a four-hour treatment cycle consisting of one hour in the anoxic stage and three hours in the nitrification stage. [Diagram 2] FIG. 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. [Diagram 3] FIG. 3 is a schematic diagram showing a liquid property determination system 1 according to an 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. [Diagram 5] FIG. 5 is a block diagram showing the functional configuration of the liquid type determining means 40. As shown in FIG. [Figure 6] FIG. 6 is a flow chart for automatically determining the property of the liquid by the determining unit 411. [Figure 7] FIG. 7 is a flow chart 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 configuration diagram showing a biological treatment determination system 2 according to one embodiment of the biological treatment determination system. [Figure 9] FIG. 9 is a flow chart showing the procedure for determining the liquid property by the determining unit 411 in the biological treatment determining system 2. As shown in FIG. [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 PREFERRED EMBODIMENTS

[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. In addition, 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, include" means that elements other than those explicitly stated to be included can be added (same meaning as "comprise at least"), but also encompasses "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 including the numerical values ​​before and after it, and also includes a range excluding one of the included limits. For example, "0% to 100%" can mean 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, items that are less relevant to the present invention are omitted. Note that the direction indicated by the arrow UP (→UP) shown appropriately in each drawing is the upward vertical direction.

[0018] [Summary of the Invention] The liquid property determination system includes, as 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 a 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 is aerated or otherwise enriched in dissolved oxygen, ammonia in the treated water is oxidatively converted to nitrate by the action of aerobic nitrifying microorganisms (nitrification reaction). Next, when the dissolved oxygen in the treated water decreases, nitrate is reductively converted to nitrogen by the action of anaerobic denitrifying microorganisms (denitrification reaction). The processes based on nitrification and denitrification reactions, nitrification and denitrification reactions are called nitrification and denitrification treatments, nitrification treatments and denitrification treatments, respectively.

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

[0021] Ordinary household wastewater has a pH of 7 to 10, which is on the neutral to alkaline side. The pH of such household 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 the case of nitrification treatment, even if the dissolved oxygen concentration of the household wastewater is sufficient, if the pH of the treated water is on the alkaline side, it means 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 means that the nitrification reaction has progressed sufficiently. In this way, if the dissolved oxygen concentration of the 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 the denitrification treatment, when 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, the pH of the treated water being on the neutral to alkaline side indicates that the denitrification reaction has progressed sufficiently. In this way, when 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 studied various methods for monitoring the pH of treated water. In order to simulate biological treatment of domestic wastewater, urea, which is a simulated wastewater, is added to a biological treatment tank and aeration is performed. The carbon dioxide concentration of 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 the form of carbon dioxide that was dissolved in the anoxic state before the start of aeration and carbon dioxide that was generated by decomposing urea by heterotrophic bacteria. In addition, ammonia generated by hydrolysis of urea is oxidized by nitrifying bacteria to generate nitric acid through nitrification, which reduces the pH. Next, a decomposable organic matter that is easily decomposed by microorganisms, such as a lower alcohol such as ethanol, is added as a hydrogen donor to the domestic wastewater in the biological treatment tank, and an anoxic state is created without aeration, so that denitrifying bacteria reduce nitric acid to generate nitrogen gas (anoxic stage or denitrification stage). At this stage, the carbon dioxide concentration of the exhaust gas discharged from the exhaust port of the biological treatment tank is very low, and it is considered that the carbon dioxide generated by the decomposition of the decomposable organic matter by microorganisms is dissolved in the treated water. In this stage, the pH also rises as nitrate is reduced. Next, a nitrification stage was carried out by adding urea to the biological treatment tank and aerating it, followed by an anoxic stage. After that, the nitrification stage and anoxic stage were alternately repeated.

[0025] By carrying out this experiment, the inventors discovered that the measurement waveform obtained by continuously plotting the carbon dioxide concentration measured in the nitrification stage had 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 was on the alkaline side, neutral side, or acidic side, the measured carbon dioxide concentration waveform showed a different pattern (Figures 1 and 2).

[0026] Figure 1 shows the results of continuous measurements of carbon dioxide concentration (CO2) and pH of the treated water in the biological treatment tank while repeating a total of four-hour treatment cycle consisting of one hour in the anoxic stage and three hours in the nitrification stage. Figure 2 also 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 the nitrification stage.

[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 presumably because, when 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 waveform of the carbon dioxide concentration 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, when 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 instantly 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 an indicator waveform of carbon dioxide concentration, which serves as an indicator, obtained by measuring wastewater whose pH (alkaline, neutral, or acidic) is known immediately after it flows 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] In addition, in the biological treatment tank in the denitrification stage, by aerating with nitrogen gas instead of air, dissolved carbon dioxide can be forcibly discharged while maintaining an anoxic state. This allows for the measurement waveform of carbon dioxide concentration patterned for each pH of the treated water to be obtained, so if an index waveform of the index carbon dioxide concentration is obtained in the same way, the pH of the treated water in the biological treatment tank can be determined as a liquid property, and the progress of the denitrification process can be determined from that.

[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, have been created based on the findings discovered for the first time by the inventors as described above.

[0032] [Liquidity determination system] A liquid property determining 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 are 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 facility 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 be a liquid containing solid matter such as crushed matter.

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

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

[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 degree of progress of biological treatment, for example, nitrification treatment and denitrification treatment, 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 so that the biological treatment proceeds smoothly, for example by adding an operation to improve the progress of the biological treatment. A liquid property determination system that enables such control is also called a liquid property control system. In this way, the liquid property determination system can take the form of a biological treatment determination system and a biological treatment control system, depending on the application.

[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. In FIG. 3, for convenience, 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 are illustrated. In FIG. 3, the valve 51 is in a closed state. In addition, the carbon dioxide concentration measurement means 30 is disposed on the exhaust pipe 50. However, the exhaust pipe 50 may be branched, and thus, a part of the exhaust from the exhaust pipe 50 may be branched and flow into the carbon dioxide concentration measurement means 30, or the whole of the exhaust may flow into the carbon dioxide concentration measurement means 30. In addition, by branching the exhaust pipe 50 in this way, it is possible to take measures against condensation and suppress 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 may not be provided.

[0039] The liquid containing means 10 is configured to be capable of containing a liquid 11, and to have an exhaust port 12. Exhaust gas discharged from the liquid containing means 10 is, in principle, exhausted to the outside of the liquid containing means 10 through the exhaust port 12. The liquid containing means 10 is preferably sealed so that exhaust gas is exhausted through the exhaust port 12. The liquid containing means 10 may have an inlet for receiving liquid from outside the system, and may have 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. Also, the liquid storage means 10 may be called a biological treatment tank when the liquid 11 is used for biologically treating the liquid 11.

[0041] When the liquid storage means 10 is a biological treatment tank, the liquid 11 is treated using organisms such as microorganisms. The microorganisms may be aerobic microorganisms, anaerobic microorganisms, or a combination of these. The liquid storage means 10 may hold a mixture of aerobic microorganisms 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 may be structured to have two or more tanks by providing, for example, a partition such as a permeable membrane that allows water to pass through but does not allow microorganisms to pass through.

[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. Fig. 4 illustrates a state in which the gas 21 is being supplied into the liquid 11 by the gas supply means 20. In Fig. 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 carbon dioxide, 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 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, a CO2 sensor, or the like. The carbon dioxide concentration may be measured, for example, based on the amount of infrared light absorbed by carbon dioxide. In the exhaust pipe 50, the portion in which the carbon dioxide concentration measuring means 30 is disposed is called the carbon dioxide measuring section 501. The carbon dioxide concentration measuring means 30 measures the carbon dioxide concentration in the exhaust passing through the carbon dioxide measuring section 501, and outputs the result as a numerical value (units include ppm and %).

[0046] The carbon dioxide concentration measuring means 30 can also be disposed 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 detection value of the carbon dioxide concentration measuring means 30.

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

[0052] The memory unit 420 is composed of a storage device, and stores at least a judgment program 421 and an index value 422 that is an index carbon dioxide concentration. The memory unit 420 may store a detection value of the carbon dioxide concentration measuring means 30, an output value that is a judgment result from the judgment unit 411, and the like. The judgment program 421 functions to cause the judgment unit 411 to judge the liquid property of the liquid 11 based on the detection 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 a detection value of the carbon dioxide concentration measuring means 30. The determination unit 411 determines the liquid property of the liquid 11 by comparing the carbon dioxide concentration, which is a detection value of the carbon dioxide concentration measuring means 30 (also referred to as a 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. In the comparison, it is preferable to compare 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. It is preferable that the liquid type determination means 40 outputs the measurement waveform, or both the measurement waveform and the index waveform. The comparison between the measurement waveform and the index waveform may be automatically determined by the determination unit 411 using AI (Artificial Intelligence) or the like based on the width of the peak, the tendency of change in the rate of change, the magnitude of the integral value of the waveform over a predetermined time, etc., or may be manually determined by visual inspection based on the output waveform.

[0055] Fig. 6 shows a flowchart for the case where the determination unit 411 determines the property of the liquid based on the comparison between the measurement waveform and the index waveform. Note that Fig. 6 is a flowchart for the case where the property is pH and the pH of the liquid is on the acidic side according to the index waveform.

[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 be used as a measured waveform (S102). Next, the measured waveform is compared with an index value 422, which is a previously created index waveform stored in the storage 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 assumed to be on the alkaline side.

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

[0059] 7 shows a flowchart of the liquid property determination by the determination unit 411 when the liquid property is various pH and the number of index waveforms is three. The index waveforms are pattern 1 created using the carbon dioxide concentration when the liquid pH is on the alkaline side, pattern 2 created using the carbon dioxide concentration when the liquid pH is on the neutral side, and pattern 3 created using the carbon dioxide concentration when the liquid pH is on the acidic side. The index waveforms of patterns 1 to 3 are, for example, as illustrated in FIGS. 2A to C.

[0060] As illustrated in Fig. 7, the determination unit 411 acquires continuous data of the carbon dioxide concentration in the exhaust 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 measurement waveform pattern is compared with the index waveform patterns 1 to 3 stored in the memory unit 420 (S203). If the measurement waveform and index waveform pattern 1 are identical or similar, it is determined that the pH of the liquid is on the alkaline side (S204), if the measurement waveform and index waveform pattern 2 are identical or similar, it is determined that the pH of the liquid is near neutral (S205), or if the measurement waveform and index waveform pattern 3 are identical or similar, it is determined 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 storage means, the gas supply means, the carbon dioxide concentration measurement 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] As long as the exhaust pipe 50 can deliver the exhaust from the liquid containing means 10 to the carbon dioxide concentration measuring means 30, there are no particular limitations on the material, diameter, length, etc., and it may or may not be branched.

[0063] The valve 51 may be, for example, a diaphragm valve, a ball valve, a solenoid valve, or the like, but is preferably a solenoid valve in order to electronically control the opening / closing and the opening degree. 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 assessment 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 includes 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 determination system 1 in Figs. 3 and 4 are given the same reference numerals. However, the liquid storage means 10 is read as the biological treatment tank 10, and the liquid 11 is 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 supplying means 60. The organic matter supplying means 60 is configured to be able to supply organic matter to the treatment water 11 in the biological treatment tank 10. The organic matter supplying means 60 supplies the organic matter to the biological treatment tank 10 by a pump 61. However, the organic matter supplying means 60 may supply the organic matter by free fall. When the organic matter is supplied by free fall, a valve such as a solenoid valve may be used instead of the pump 61 to adjust the supply speed, or these may not be used.

[0068] Organic matter that serves as a hydrogen donor serves as a nutrient source for denitrifying bacteria. When 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, that is, easily decomposable organic matter, may be used, and 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 and ethanol, and 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 determination of the liquid property by the determining unit 411 in the biological treatment determination system 2.

[0070] Organic matter is supplied to the biological treatment tank 10 by the organic matter supplying means 60 (S301). Next, the organic matter is assimilated by microorganisms in the treated water 11 in the biological treatment tank 10, and the dissolved oxygen in the treated water 11 is sufficiently reduced to create 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 and the type and amount of microorganisms, for example, but is from several minutes to several tens of hours, and preferably from 30 minutes to 2 hours. The reduction in dissolved oxygen can be confirmed by the carbon dioxide concentration measured by the carbon dioxide concentration measuring means 30 being barely detectable.

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

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

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

[0074] The index waveform is a waveform obtained by adding easily decomposable organic matter to wastewater immediately after it is received in the biological treatment tank 10, maintaining an anoxic state, starting aeration, and measuring the carbon dioxide concentration until a predetermined time has elapsed, in the same manner as the measurement waveform. The index waveform may be an index waveform when the wastewater is neutral. Similarly, an index waveform when the liquid is on the alkaline, neutral, or acidic side may 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 cycle of 4 hours in total, consisting of 1 hour of anoxic state and 3 hours of aeration time. 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 shape of the carbon dioxide concentration peak becomes sharper (narrower, higher). On the other hand, as the denitrification reaction progresses, the nitrate concentration decreases and the pH increases, the shape of the carbon dioxide concentration peak becomes broader (wider, lower).

[0076] In the biological treatment determination system 2, the liquid property determining means 40 is preferably further configured to be able to determine the state of nitrification 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 as to appropriately biologically treat the water.

[0078] In the biological treatment control system, the liquid property determining means is configured to determine the 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 capable of controlling the biological treatment. The control of the biological treatment in the biological treatment control system may be realized by adding a function to the liquid property determination means, or may utilize a biological treatment control means different from the liquid property determination means. However, in order to simplify the configuration of the biological treatment control system, it is preferable that the liquid property determination means also has a biological treatment control function.

[0080] A specific embodiment of the liquid property determining means having a biological treatment control function, that is, a liquid property determining means 41, will be described with reference to Fig. 10. In Fig. 10, components common to the liquid property determining means 40 in Fig. 5 are given 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 capable of acquiring the determination information of the determination unit 411, and is configured 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 an output value from the control unit 412 to the gas supply means 20 and the organic matter 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 acquired 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 supplying means 20 to continue the supply of air or oxygen from the gas supplying means 20 to the biological treatment tank 10 to continue the nitrification treatment. On the other hand, when the control unit 412 has acquired determination information from the determination unit 411 that the pH of the treatment water 11 is on the acidic side, it controls the gas supplying means 20 to stop the supply of air or oxygen from the gas supplying means 20 to the biological treatment tank 10 to end the nitrification treatment.

[0086] When the treatment water 11 is being subjected to denitrification treatment, the control unit 412, which has obtained judgment information from the judgment unit 411 that the liquid property of the treatment 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 the biological treatment of the liquid can be determined, and further, the biological treatment can be controlled so as to be performed appropriately. Since these systems can be simply configured, they can be applied to, for example, an autonomous circulation type water purification device.

[0088] In general, autonomous circulation water purification systems are mainly divided into water treatment systems for toilet wastewater from household wastewater and water treatment systems for other types of miscellaneous wastewater (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 is near neutral, since this not only monitors the nitrification / denitrification process (nitrification reduces the pH by converting ammonia to nitric acid in an aerobic state (with aeration), while denitrification increases the pH by removing nitric acid as nitrogen gas in an anoxic state), but also allows for monitoring the inflow of unexpected acids and alkalis caused by the user. However, pH sensors are liquid-contacting types, and are expensive and have durability issues, making it unrealistic to use them in autonomous circulation water purification systems.

[0089] Therefore, if a non-wetted, inexpensive, and durable CO2 sensor could be used to determine the pH of the wastewater being treated, it would be possible to monitor whether the pH of the wastewater being treated is near neutral, even in an autonomous circulation water purification device.

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

[0091] Therefore, a specific preferred embodiment of the liquid property determination system, biological treatment determination system, and biological treatment control system of 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 the 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 the liquid containing means and measuring the carbon dioxide concentration in the exhaust gas discharged from the 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 of one aspect of the present invention. The biological treatment determination method includes, for example, a biodegradation step of biologically decomposing organic matter added to the biological treatment water contained in a biological treatment tank by consuming the dissolved oxygen in the biological treatment water, a measurement step of supplying gas to the biological treatment water in which the 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, and a determination step of collating the measured carbon dioxide concentration with an index carbon dioxide concentration to determine the state of the biological treatment. The determination step is preferably a determination step of collating 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, denitrification treatment, or both of these treatments.

[0094] Another aspect of the present invention is a biological treatment control method realized by the biological treatment control system of one aspect of the present invention, etc. The biological treatment control method includes, for example, a biodecomposition step of biologically decomposing organic matter added to the biological treatment water contained in a biological treatment tank by consuming dissolved oxygen in the biological treatment water, a measurement step of supplying gas to the biological treatment 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 collating the measured carbon dioxide concentration with an index carbon dioxide concentration to determine the pH of the biological treatment water and thereby determine the state of nitrification treatment and / or denitrification treatment, and a control step of controlling the biological treatment of the biological treatment water so that the pH of the biological treatment water is on the alkaline side and thus the nitrification reaction continues, and / or so that the pH of the biological treatment water is on the acidic side and thus the denitrification reaction continues. [Industrial Applicability]

[0095] The liquid type 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 type or biological treatment state based on the carbon dioxide concentration in the exhaust gas, and can also control the biological treatment to be carried out appropriately, and therefore can be used, for example, in an autonomous circulation type water purification device 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 measuring means 40 Liquidity determination means 401 Processing section 411 Judgment section 412 Control section 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 a carbon dioxide concentration in the exhaust gas discharged from an exhaust port of the liquid storage means; and The liquid property determining 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 measuring means with an index carbon dioxide concentration; and The index carbon dioxide concentration is the carbon dioxide concentration of a liquid that is contained in the liquid containing means and has a neutral, acidic or alkaline pH. The liquid determination system.

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

3. The liquid property determination system according to claim 2 , wherein the wastewater treatment tank is a biological treatment tank.

4. A biological treatment determination system, comprising: A liquid property determination system according to claim 3 and an organic matter supply means, The organic matter supplying means is capable of supplying an organic matter 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.

5. The biological treatment determination system according to claim 4, 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.

6. The biological treatment determination system according to claim 4 , wherein the gas is selected from the group consisting of air, oxygen, ozone, and nitrogen.

7. The biological treatment determination system according to claim 4 , wherein the liquid property determining means is further capable of determining a state of biological treatment of the liquid based on the determined liquid property of the liquid.

8. 1. A biological treatment control system comprising: The biological treatment determination system according to claim 7 is provided, The biological treatment control system, wherein the liquid property determining means is further capable of controlling biological treatment of the liquid based on the determined state of biological treatment of the liquid.

9. A method for determining a liquid property, comprising: a measuring step of supplying a gas to the liquid contained in the liquid containing means and measuring a carbon dioxide concentration in exhaust gas discharged from an exhaust port of the liquid containing means; A determination step of comparing the measured carbon dioxide concentration with an index carbon dioxide concentration to determine the liquid property of the liquid; and The index carbon dioxide concentration is the carbon dioxide concentration of a liquid that is contained in the liquid containing means and has a neutral, acidic or alkaline pH. The liquid property determination method.

10. A biological treatment determination method, comprising: a biodegradation process in which organic matter added to the biologically treated water contained in the biological treatment tank is biologically decomposed by consuming the 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 an 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 pH of the biological treatment water, thereby determining the state of nitrification treatment and / or denitrification treatment.

11. 1. A biological treatment control method comprising: a biodegradation process in which organic matter added to the biologically treated water contained in the biological treatment tank is biologically decomposed by consuming the 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 an exhaust port of the biological treatment tank; A determination step of collating 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; 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 allowing the nitrification reaction to continue, and / or so that the pH of the biologically treated water is on the acidic side, thereby allowing the denitrification reaction to continue; The biological treatment control method comprising the steps of:

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