Odor Substance Extraction Device

Abstract

To provide an odorous substance extraction device that successively extracts an odorous substance in a test water and measures the concentrations of odorous substances in the test water.SOLUTION: The odorous substance extraction device according to an embodiment comprises: a heater 4 for heating a test water; a gas-liquid contact device 8 for causing the heated test water to be gas-liquid contacted with a sample gas and ejecting an odorous substance-containing gas in which an odorous gas contained in the test waster has been extracted to the sample gas; a dehumidifier 10 for dehumidifying the odorous gas-containing gas; and a computation device 13 for computing an odorous substance concentration in the test water using the flow rate and odorous substance concentration in the odorous substance-containing gas ejected from the dehumidifier 10 and the flow rate of the test water flowing into the heater 4.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to an odorant extraction device. [Background technology]

[0002] In water purification plants, for example, water taken from rivers and lakes is purified to produce water that meets the water quality standards set by the Water Supply Act and other regulations, and is then supplied to target areas. Water supplied as drinking water must meet various water quality standards, and for example, there are also specified water quality standards for odorous substances that cause the odor of drinking water.

[0003] In recent years, water temperatures have been rising year by year, particularly due to global warming, creating an environment in which odor-causing algae can easily proliferate. As a result, there have been an increasing number of cases of odor problems being reported even at water purification plants where odor problems had not previously been observed.

[0004] However, in order to sufficiently remove the odor from water, very low concentrations of odorous substances must be detected, and in the past, it was necessary to detect the odorous substances using expensive analytical equipment by concentrating the odorous substances over a long period of time.

[0005] There are two odorous substances for which water quality standards have been set for drinking water: 2-MIB (2-methylisoborneol) and geosmin. The water quality standards for these odorous substances are set at a very low concentration of 10ng / L, and they are characterized by low concentrations in water and low vaporization into the gas phase. For this reason, quantitative detection of odorous substances is performed using expensive analytical equipment for advanced analysis.

[0006] For example, online analytical devices that automate the process from water sampling to quantitative detection of 2-MIB and geosmin are now in practical use, but these systems are much more expensive and complex than benchtop analytical devices used for manual analysis, and cannot be easily introduced.

[0007] Furthermore, such an analyzer is, for example, an online analyzer that uses gas chromatography mass spectrometry (CG / MS), which takes time to separate the target substance in a column and requires the column to be regenerated for each measurement, so that measurement takes time, and although it is an online device, it only outputs one data point per hour. In other words, it is an analyzer that performs measurement once per hour (one batch).

[0008] Furthermore, in GC / MS, a purge and trap method may be adopted as a pretreatment method, in which a liquid sample is brought into contact with a gas to expel (purge) the target substance into the gas phase, and then the target substance is collected (trapped) by an adsorbent. The target substance desorbed from the adsorbent in the pretreatment is introduced into the GC / MS, where quantitative analysis is performed. The concentration rate of the target substance by the purge and trap method is generally said to be about 100 to 250 times. As described above, in GC / MS, the pretreatment involves the steps of adsorption and desorption, making it difficult to continuously extract and measure the target substance. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent No. 6825157 Summary of the Invention [Problem to be solved by the invention]

[0010] An embodiment of the present invention has been made in consideration of the above circumstances, and aims to provide an odorant extraction device that continuously extracts odorants in test water and measures the concentration of odorants in the test water. [Means for solving the problem]

[0011] The odorant extraction device according to the embodiment includes a heater for heating test water, a gas-liquid contactor for bringing the heated test water into gas-liquid contact with a sample gas and discharging an odorant-containing gas from which odorants contained in the test water have been extracted into the sample gas, a dehumidifier for dehumidifying the odorant-containing gas, and a calculation device for calculating the odorant concentration in the test water before the odorant extraction using the flow rate and odorant concentration of the odorant-containing gas discharged from the dehumidifier and the flow rate of the test water flowing into the heater. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration example of an odorant extraction device according to a first embodiment. [Diagram 2] FIG. 2 is a diagram showing an example of the value of the dimensionless Henry's constant of 2-MIB versus temperature. [Diagram 3] FIG. 3 is a diagram showing an example of a dimensionless Henry's constant derived by the present inventors through experiments. [Figure 4] FIG. 4 is a diagram illustrating a schematic configuration example of an odorant extraction device according to the second embodiment. [Diagram 5] FIG. 5 is a diagram illustrating a schematic configuration example of an odorant extraction device according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an odorant extraction device according to an embodiment will be described in detail with reference to the drawings. FIG. 1 is a diagram illustrating a schematic configuration example of an odorant extraction device according to a first embodiment. The odorant extraction device of this embodiment includes a heat exchanger 2, a heater 4, a heater controller 6, a boost pump P1, a gas-liquid contactor 8, an air pump P2, a dehumidifier 10, a return pump P3, temperature sensors T1-T3, flow meters F1-F3, an odorant concentration meter (gas concentration meter) 12A, and a calculation device 13.

[0014] The heat exchanger 2 exchanges thermal energy between the raw water (test water) flowing into the odorous substance extraction device and the return water after circulating inside the odorous substance extraction device. The heat exchanger 2 is of a double-tube or plate type, and exchanges thermal energy between the fluids by passing water in a countercurrent. Since the return water after circulating inside the odorous substance extraction device is at a higher temperature than the raw water, thermal energy is transferred from the return water to the raw water in the heat exchanger 2. This reduces the load on the heater 4, which will be described later.

[0015] In the odorant extraction device of this embodiment, odorant-containing gas is continuously supplied to an odorant concentration meter 12A described later. For example, when the sensitivity of the odorant concentration meter 12A is about 1 to 10 ppb, several tens to several hundreds ml / min of odorant-containing gas is required in consideration of the detection sensitivity of odorants. For this reason, the raw water required to obtain a sufficient amount of odorant-containing gas may reach 10 L / min. In order to heat a large amount of raw water to 90°C by a heater 4 described later to extract odorants into the gas phase, several tens of kW of thermal energy is required, which results in excessive running costs as a water quality meter. Therefore, in this embodiment, in the heat exchanger 2, heat is recovered from the raw water (hot water) returned after odorant extraction, and the raw water (test water) is preheated in front of the heater 4, thereby reducing the energy consumed by the heater 4 to about several hundreds W to several kW. In this embodiment, the heater 4 is, for example, a 3 kW heater.

[0016] The heater 4 is, for example, an in-line piping heater, which heats the piping through which the raw water (test water) flows so that the raw water discharged from the heat exchanger 2 reaches a predetermined temperature. In the odorant extraction device of this embodiment, the raw water is heated by the heater 4, thereby heating the test water that is continuously supplied, and creating an environment in which the target odorant is easily extracted into the gas phase based on the principle of gas-liquid equilibrium.

[0017] For example, 2-MIB, an odorant, is mostly present in water in a gas-liquid equilibrium state at room temperature, and the gas-liquid concentration ratio (ratio of concentration in gas to concentration in liquid) is 1 / 500 in an environment of 20°C, and the gas-liquid concentration ratio is about 1 / 50 even in an environment of 40°C. The inventors of the present application conducted a test and found that the gas-liquid concentration ratio can be improved to about 3 by raising the test water (raw water) to 90°C. From the above, in this embodiment, it is preferable that the heater 4 heats the raw water to 80°C or higher, and more preferably to 90°C or higher. In this embodiment, the heater 4 continuously heats the raw water to 90°C or higher (for example, 92°C to 93°C), taking into account the temperature drop of the test water between the heater 4 and the gas-liquid contactor 8.

[0018] The heater controller 6 controls the heater 4 based on the temperature acquired from a temperature sensor T1 that detects the temperature of the raw water discharged from the heater 4 so that the raw water temperature becomes a predetermined temperature. The boost pump P1 increases the pressure of the raw water discharged from the heater 4 and outputs it to the gas-liquid contactor 8.

[0019] The gas-liquid contactor 8 brings high-pressure raw water (test water) discharged from the booster pump P1 into contact with gas (sample gas), continuously extracts odorous substances from the raw water into the air, and discharges the odorous substance-containing gas. In this embodiment, for example, air can be used as the sample gas. The gas-liquid contact may be achieved by, for example, bubbling, which involves sending a gas (sample gas) to the liquid using an air pump P2, spraying, which involves spraying a liquid into the gas, or using a membrane. For bubbling, a porous body may be used, or microbubbles may be formed using a Venturi tube or the like. The flow rate of the sample gas sent to the gas-liquid contactor 8 by the air pump P2 is measured by a flowmeter F1. For spraying, a nozzle for one fluid or a nozzle for two fluids may be used. For example, a hydrophobic membrane may be used to efficiently achieve gas-liquid contact.

[0020] The raw water after odorous substances have been extracted in the gas-liquid contactor 8 is pumped to the heat exchanger 2 by the return pump P3, passes through the heat exchanger 2 and is discharged. The temperature sensor T3 detects the environmental temperature (extraction temperature of odorous substances) at which gas-liquid contact is performed in the gas-liquid contactor 8, and supplies the detected value to the calculator 13. The dehumidifier 10 dehumidifies and discharges the odorous substance-containing gas discharged from the gas-liquid contactor 8. The dehumidifier 10 is used because the odorous substance-containing gas discharged from the gas-liquid contactor 8 contains a lot of water vapor, and the water vapor becomes an obstacle to measurement when measuring trace values ​​with the odorous substance concentration meter 12A arranged downstream.

[0021] For example, when raw water containing 10 ng / L of dissolved 2-MIB is subjected to gas-liquid equilibrium in an environment of 90°C, 2-MIB is extracted into the gas phase. 3 ) of water vapor can be extracted. If the temperature of this odorant-containing gas drops before it reaches odorant concentration meter 12A, which will be described later, the water vapor will condense and adversely affect the measurement of odorant concentration. In addition, the odorant concentration meter 12A can be a semiconductor type, a type with a modified quartz crystal oscillator, an infrared absorption type, or the like, but the presence of a large amount of water vapor will cause noise and a decrease in sensitivity in all of these types.

[0022] In order to accurately measure the concentration of odorants in the odorant concentration meter 12A, it is desirable to supply odorant-containing gas at a constant temperature and humidity. 3 ) and supplying an odorant-containing gas, the odorant concentration meter 12A as described above can generally operate stably.

[0023] Considering the above, in order to maintain a constant humidity of the odorant-containing gas, the odorant extraction device of this embodiment is equipped with, for example, a cooling-type dehumidifier 10. Here, for example, a membrane-type dehumidifier is not recommended because it causes a decrease in accuracy by adsorbing a small amount of odorant. Also, even in a cooling-type dehumidifier, a certain proportion of odorant may be absorbed into the condensed water, but since sufficient time to reach gas-liquid equilibrium is not ensured in the dehumidifier, most of the odorant can remain in the gas phase.

[0024] The odorant-containing gas discharged from the dehumidifier 10 is supplied to the odorant concentration meter 12A. The temperature sensor T2 detects the temperature of the odorant-containing gas discharged from the dehumidifier 10, i.e., the odorant-containing gas supplied to the odorant concentration meter 12A.

[0025] The odorant concentration meter 12A measures the odorant concentration in the odorant-containing gas discharged from the dehumidifier 10, and supplies the measured value to the calculation device 13. For example, a semiconductor concentration meter as the odorant concentration meter 12A has a detection capability on the order of ppm. For example, some laser concentration meters as the odorant concentration meter 12A are capable of detecting 1 to 10 ppb. For example, a quartz oscillator modified with a sensitive film or MOF (metal organic framework) may be used as the odorant concentration meter 12A to measure odors using the change in frequency. In the odorant extraction device of this embodiment, it is assumed that a laser concentration meter can detect 1 ppb, and the odorant-containing gas supplied to the odorant concentration meter 12A has a 2-MIB concentration of 1 ppb or more when the 2-MIB concentration in water is 10 ng / L, and the flow rate of raw water used to extract odorants is calculated from, for example, a dimensionless Henry constant described later and a gas flow rate required for the odorant concentration meter 12A.

[0026] The arithmetic device 13 includes, for example, at least one processor and a memory in which a program executed by the processor is stored, and can realize various functions by software. The arithmetic device 13 can calculate the odorant concentration (a) in the raw water (test water flowing into the heater 4) before odorant extraction by the following formula using the odorant concentration (d) in the gas measured by the odorant concentration meter 12A, the odorant concentration (x) in the raw water after odorant extraction, the flow rate (flow rate of the test water flowing into the heater 4) (b) of the raw water used for odorant extraction detected by the flow meter F2, and the flow rate (c) of the odorant-containing gas measured by the flow meter F3.

[0027] a = (b + cH) / (bx) … (1) x=d / H…(2) In the above formula, H is a dimensionless Henry's constant preset according to the odorant extraction temperature. The computing device 13 can calculate the dimensionless Henry's constant from the environmental temperature (odorant extraction temperature) in the gas-liquid contactor 8 detected by the temperature sensor T3.

[0028] The odorous substances stipulated in the water quality standards are 2-MIB and geosmin, both of which have low concentrations in water and are difficult to volatilize into the gas phase.The water quality standards for these odorous substances have a very low concentration of 10ng / L.

[0029] The volatilization of a substance into the gas phase can be expressed using the dimensionless Henry's constant, which indicates the relationship of gas-liquid equilibrium. For example, the dimensionless Henry's constant for 2-MIB at 20°C is 0.002. In other words, in a gas-liquid equilibrium state, the ratio of the concentration of 2-MIB in the air to the concentration of 2-MIB in water is 1:500, so when water with an odorant concentration of 10 ng / L, which is the water quality standard mentioned above, reaches gas-liquid equilibrium at 20°C, the concentration of 2-MIB in the gas phase will be 0.02 ng / L.

[0030] Therefore, if 2-MIB is extracted into the gas phase to detect the concentration in the gas phase, the target substance must be detected in an environment where the odorant is even more dilute. For this reason, in the purge and trap method, for example, 2-MIB is absorbed into an adsorbent such as activated carbon after gas-liquid contact, and then eluted and concentrated to a detectable level. In addition, the above method requires batch processing because an adsorbent is used, making it difficult to continuously extract odorants.

[0031] On the other hand, the inventors of the present application have focused on the temperature dependency of the dimensionless Henry's constant. FIG. 2 is a diagram showing an example of the value of the dimensionless Henry's constant of 2-MIB versus temperature. For example, the dimensionless Henry's constant of 2-MIB in an environment of 39° C. is 0.02. In other words, the gas concentration is 10 times higher in an environment of 20° C. Based on this, the inventors of the present application predicted the dimensionless Henry's constant in an environment with a further increase in temperature using a prediction formula obtained from the relationship between the environmental temperature and the dimensionless Henry's constant shown in FIG. 2, for example. The results obtained were that the dimensionless Henry's constant of 2-MIB was 1.35 in an environment of 80° C., 2.8 in an environment of 87° C., and 3.82 in an environment of 90° C.

[0032] The following describes the results of verification by the inventors of the present invention regarding the predicted value of the dimensionless Henry's constant. FIG. 3 is a diagram showing an example of a dimensionless Henry's constant derived by the present inventors through experiments.

[0033] The inventors first poured a fixed amount of 2-MIB solution into a sealable bottle whose volume had been measured in advance, sealed the bottle, and placed it in an 80°C environment created in a thermostatic bath overnight to promote gas-liquid equilibrium, and recovered the water portion the next day. The inventors then quantified the 2-MIB concentration in the recovered water, and calculated the dimensionless Henry's law constant from the 2-MIB concentrations before and after the temperature was lowered to 80°C and the volume measured in advance.

[0034] As a result of the above, although it differs depending on the concentration of the 2-MIB solution, the dimensionless Henry's constant in an 80°C environment is approximately 1.1 to 1.8, which is close to the predicted value calculated by the present inventors. This verified the validity of the prediction formula for the dimensionless Henry's constant used by the present inventors. The calculation device 13 can calculate a dimensionless Henry's constant corresponding to the environmental temperature in the gas-liquid contact device 8 detected by the temperature sensor T3, for example, using the above-mentioned dimensionless Henry's constant prediction equation whose validity has been verified.

[0035] As described above, the odorant extraction device of this embodiment can continuously extract gas containing odorants, and the odorant concentration in the odorant-containing gas can be continuously measured by the odorant concentration meter 12A disposed downstream of the dehumidifier 10. Furthermore, since the odorant extraction device of this embodiment can continuously extract high-concentration gas, it is possible to detect the odorant concentration in the raw water without using an expensive and complicated device such as a mass spectrometer.

[0036] That is, according to this embodiment, it is possible to provide an odorant extraction device that continuously extracts odorants in test water and measures the odorant concentrations in the test water.

[0037] Next, an odorant extraction device according to a second embodiment will be described in detail with reference to the drawings. In the following description of the second and third embodiments, the same components as those in the above-described first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0038] FIG. 4 is a diagram illustrating a schematic configuration example of an odorant extraction device according to the second embodiment. The odorant extraction device of this embodiment includes a filtration membrane (first membrane M1), a heat exchanger 2, a heater 4, a heater controller 6, boost pumps P1 and P4, a gas-liquid contactor 8, an air pump P2, a dehumidifier 10, a return pump P3, temperature sensors T1-T3, flow meters F1-F4, an odorant concentration meter 12A, and a calculation device 13.

[0039] The filtration membrane includes a first membrane M1 disposed in front of the heater 4. The first membrane M1 is configured to remove substances having a smaller molecular weight than odorous substances in the raw water, and may be, for example, a reverse osmosis membrane (RO membrane) or a nanofiltration membrane (NF membrane). The RO membrane allows low molecular weight components having a molecular weight of about 100 or less to pass through. The NF membrane can separate and remove substances at a lower pressure than the RO membrane. The NF membrane allows components having a size of, for example, less than several nm to pass through. The NF membrane may have an electrostatic separation effect by adding a positive or negative charge to the membrane surface, and may separate and remove ions. The RO membrane and the NF membrane can separate and remove VOCs (volatile organic compounds), ions, and the like contained in the test water (raw water).

[0040] Raw water is sent from the boost pump P4 to the first membrane M1. The raw water sent to the first membrane M1 has impurities such as VOCs and ions removed, and is discharged to the primary side. Therefore, the first membrane M1 can reduce the concentration of impurities contained in the test water discharged to the primary side. When odorants are detected by the odorant concentration meter 12A, they are affected by VOCs and ions, just like water vapor in the odorant-containing gas. The reduction in the VOC concentration and ion concentration in the test water also reduces the VOC concentration and ion concentration in the odorant-containing gas supplied to the odorant concentration meter 12A, leading to an improvement in the S / N ratio in the odorant concentration meter 12A. That is, the odorant detection device of this embodiment can improve the detection accuracy of odorants.

[0041] The test water (concentrated water) discharged from the first membrane M1 to the primary side flows into the heater 4 after passing through a heat exchanger. The water discharged to the secondary side of the first membrane M1 is drained. Since the first membrane M1 allows water to pass through to the secondary side, the test water discharged to the primary side is concentrated water with a higher concentration of odorants than the raw water. By increasing the odorant concentration in the test water at the rear stage of the first membrane M1, a higher concentration of odorant-containing gas can be supplied to the odorant concentration meter 12A when the odorants are extracted into the sample gas by heating and gas-liquid equilibrium. Considering that the problem to be solved by the odorant extraction device of this embodiment is due to the extremely low concentration of odorants in the water, concentrating the water to be treated is effective in improving the accuracy of odorant concentration detection. In addition, because a part of the raw water is discharged to the secondary side of the first membrane M1, the amount of test water is less than that of the raw water, and the energy required to heat the test water in the heater 4 can be reduced. This allows the power consumption of the odorant extraction device to be reduced.

[0042] In the odorant extraction device of this embodiment, the gas-liquid contact tank 8 has a fine bubble generator 14. A Venturi tube or the like can be used as the fine bubble generator. The fine bubble generator 14 generates fine bubbles of, for example, 1000 nm or less. By generating fine bubbles in the gas-liquid contact tank 8, 2-MIB, which tends to be hydrophobic, is adsorbed by the bubbles and becomes more likely to volatilize, thereby improving the gas-liquid contact efficiency. If the gas-liquid contact efficiency in the gas-liquid contact tank 8 is improved, the residence time of the gas in the gas-liquid contact tank 8 can be shortened, and the gas-liquid contact tank 8 can be made smaller. The flow meter F4 measures the flow rate b′ of the raw water supplied to the first membrane M1, and supplies the measurement value to the calculation device 13.

[0043] The arithmetic device 13 includes, for example, at least one processor and a memory in which a program executed by the processor is stored, and can realize various functions by software. The arithmetic device 13 can calculate the odorant concentration (a') in the raw water supplied to the first membrane M1 by the following formula using the odorant concentration (d) in the odorant-containing gas measured by the odorant concentration meter 12A, the odorant concentration (x) in the raw water after odorant extraction, the flow rate (flow rate of the test water (concentrated water) flowing into the heater 4) (b) of the test water used for odorant extraction detected by the flow meter F2, the raw water flow rate (b') supplied to the first membrane M1 measured by the flow meter F4, the flow rate (c) of the odorant-containing gas measured by the flow meter F3, and the odorant concentration (a) in the test water (concentrated water) flowing into the heater.

[0044] Here, the permeability of odorants through the first membrane M1 (the ratio of the raw water flowing into the filtration membrane to the portion not supplied to the heater 4) depends on the membrane used and the filtration conditions, so the permeability f is a value obtained by performing tests and simulations in advance under the operating conditions assumed when the odorant detection device is used. The relationship between the concentrated water flow rate b, the raw water flow rate b', the odorant concentration a' in the raw water, and the odorant concentration a in the concentrated water is expressed by the following formula in terms of the amount of odorants. a×b=a´×b´…(3) If the permeability is f, the ratio of the concentrated water to the raw water flowing into the filtration membrane is 1-f, and the concentration rate is 1 / (1-f). In this case, the relationship 1 / (1-f)=b´ / b holds. From the above formula, the odorant concentration a' in the raw water is expressed by the following formula. a´=a×(1-f)…(4)

[0045] As in the first embodiment described above, the calculation device 13 can calculate the odorant concentration (a) in the test water (concentrated water) flowing into the heater 4 using the above-mentioned formulas (1) and (2). Therefore, the calculation device 13 can calculate the odorant concentration a' in the raw water supplied to the first membrane M1 using the above-mentioned formulas (1), (2), and (4).

[0046] According to the odorant extraction device of this embodiment, as in the first embodiment, it is possible to continuously extract gas containing odorants, and the odorant concentration in the odorant-containing gas can be continuously measured by the odorant concentration meter 12A arranged downstream of the dehumidifier 10. Furthermore, according to the odorant extraction device of this embodiment, it is possible to continuously extract a high-concentration odorant-containing gas, and therefore it is possible to detect the odorant concentration in the raw water without using an expensive and complicated device such as a mass spectrometer. That is, according to this embodiment, it is possible to provide an odorant extraction device that continuously extracts odorants in test water and measures the odorant concentrations in the test water.

[0047] Next, an odorant extraction device according to a third embodiment will be described in detail with reference to the drawings. FIG. 5 is a diagram illustrating a schematic configuration example of an odorant extraction device according to the third embodiment. The odorant extraction device of this embodiment differs from the above-mentioned second embodiment in that the filtration membrane further includes a second membrane M2 arranged in front of the first membrane M1. In addition, in the odorant extraction device of this embodiment, the pump P2 is a circulation pump that circulates the test water between the fine bubble generator 14 and the gas-liquid contact tank 8, instead of the air pump in the first and second embodiments.

[0048] The second membrane M2 is configured to remove substances having a molecular weight larger than that of odorous substances, and may be, for example, an ultrafiltration membrane (UF). The UF membrane can separate substances having a molecular weight larger than about 3000, and remove substances having a molecular weight larger than that of odorous substances, such as 2-MIB having a molecular weight of 168.

[0049] By adding the second membrane M2 to the front of the first membrane M1, it is possible to remove the contaminants, soluble organic matter (NOM) and volatile organic matter (VOC), which is a part of the NOM. In particular, VOCs become noise when the odorant concentration is measured by the odorant concentration meter 12A in the rear stage, so removing the VOCs can improve the S / N ratio of the odorant concentration meter 12A. In addition, it is known that NOM such as humic acid inhibits the volatilization of the odorant 2-MIB (the Henry's constant decreases in the presence of NOM), so the volatilization rate of 2-MIB can be increased by removing NOM, and the S / N ratio can be increased by supplying a higher concentration of odorant to the odorant concentration meter 12A.

[0050] Raw water is sent to the second membrane M2 from the booster pump P5. The raw water sent to the second membrane M2 has impurities such as VOCs and ions, which have molecular weights larger than those of odorous substances, removed, and is discharged to the primary side. The test water discharged to the primary side of the second membrane M2 is sent to the first membrane M1 by the boost pump P4. The first membrane M1 removes molecules smaller than odorous substances from the test water and discharges them to the primary side.

[0051] By installing the second membrane M2 in front of the first membrane M1 as described above, it becomes possible to supply the test water from which NOVs and VOCs that cannot be removed by the first membrane M1 have been removed to the heater 4, thereby further improving the accuracy of odorant detection by the odorant concentration meter 12A.

[0052] The odor substance extraction device of this embodiment also has a fine bubble generator 14 disposed in front of the pump P2. A Venturi tube or the like can be used as the fine bubble generator 14. The test water is supplied from the gas-liquid contact device 8 to the fine bubble generator 14, which generates fine bubbles of, for example, 1000 nm or less in the test water. The test water containing the fine bubbles generated by the fine bubble generator 14 is sent to the gas-liquid contact tank 8 by the pump P2. By generating fine bubbles in the test water, 2-MIB, which has a hydrophobic tendency, is adsorbed by the bubbles and easily volatilized, thereby improving the gas-liquid contact efficiency. If the gas-liquid contact efficiency in the gas-liquid contact tank 8 is improved, the residence time of the gas in the gas-liquid contact tank 8 can be shortened, and the gas-liquid contact tank 8 can be made smaller.

[0053] The flow meter F4 measures the flow rate b′ of the raw water supplied to the second membrane M2, and supplies the measurement value to the calculation device 13. The arithmetic device 13 includes, for example, at least one processor and a memory in which a program executed by the processor is stored, and can realize various functions by software. The arithmetic device 13 can calculate the odorant concentration (a') in the raw water supplied to the first membrane M1 by the following formula using the odorant concentration (d) in the odorant-containing gas measured by the odorant concentration meter 12A, the odorant concentration (x) in the raw water after odorant extraction, the flow rate (flow rate of the test water (concentrated water) flowing into the heater 4) (b) of the test water used for odorant extraction detected by the flow meter F2, the raw water flow rate (b') supplied to the second membrane M2 measured by the flow meter F4, the flow rate (c) of the odorant-containing gas measured by the flow meter F3, and the odorant concentration (a) in the test water (concentrated water) flowing into the heater.

[0054] Here, the permeability of odorants through the first membrane M1 and the second membrane M2 (the ratio of the raw water flowing into the filtration membrane to the portion not supplied to the heater 4) depends on the membrane used and the filtration conditions, so the permeability f is a value obtained by performing tests and simulations in advance under the operating conditions assumed when the odorant detection device is used. The relationship between the concentrated water flow rate b, the raw water flow rate b', the odorant concentration a' in the raw water, and the odorant concentration a in the concentrated water is expressed by the above formulas (3) and (4) in terms of the amount of odorant.

[0055] As in the first embodiment described above, the calculation device 13 can calculate the odorant concentration (a) in the test water (concentrated water) flowing into the heater 4 using the above-mentioned formulas (1) and (2). Therefore, the calculation device 13 can calculate the odorant concentration a' in the raw water supplied to the second membrane M2 using the above-mentioned formulas (1), (2), and (4) in the same manner as in the second embodiment.

[0056] According to the odorant extraction device of this embodiment, as in the first and second embodiments, it is possible to continuously extract gas containing odorants, and the odorant concentration in the odorant-containing gas can be continuously measured by the odorant concentration meter 12A arranged downstream of the dehumidifier 10. Furthermore, according to the odorant extraction device of this embodiment, since it is possible to continuously extract high-concentration gas, it is possible to detect the odorant concentration in the raw water without using an expensive and complicated device such as a mass spectrometer. That is, according to this embodiment, it is possible to provide an odorant extraction device that continuously extracts odorants in test water and measures the odorant concentrations in the test water.

[0057] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. For example, the fine bubble generator 14 in the odorant extraction device of the second and third embodiments can also be applied to the other embodiments. [Explanation of symbols]

[0058] 2...heat exchanger, 4...heater, 6...heater controller, 8...gas-liquid contactor, 10...dehumidifier, 12A...odor substance concentration meter, 13...calculator, 14...fine bubble generator, F1-F3...flow meter, T1, T2, T3...temperature sensor, P1, P4, P5...booster pump, P2...air pump, circulation pump, P3...return pump, M1...first membrane, M2...second membrane

Claims

1. A heater for heating the test water; a gas-liquid contactor that brings the heated test water into gas-liquid contact with a sample gas and discharges an odorant-containing gas in which odorants contained in the test water are extracted into the sample gas; a dehumidifier for dehumidifying the odorous substance-containing gas; and a calculation device that calculates the odorant concentration in the test water before the odorant extraction using the flow rate and odorant concentration of the odorant-containing gas discharged from the dehumidifier and the flow rate of the test water flowing into the heater.

2. The test water may further include a filter membrane arranged in front of the heater and configured to supply the test water to the heater from which at least substances having a molecular weight smaller than that of odorous substances have been removed.

2. The odorant extraction device according to claim 1, wherein the calculation device calculates the odorant concentration in the test water before the odorant extraction using the flow rate and odorant concentration of the odorant-containing gas discharged from the dehumidifier, the flow rate of the test water flowing from the filtration membrane to the heater, and the flow rate of the test water flowing into the filtration membrane.

3. 3. The odorant extraction device according to claim 2, wherein the filtration membrane comprises a first membrane that supplies the test water from which substances having molecular weights smaller than those of the odorants have been removed to the heater.

4. The odorant extraction device of claim 3, further comprising a second membrane arranged in front of the first membrane and supplying the test water from which substances having a molecular weight larger than that of the odorant have been removed to the first membrane.

5. 5. The odorant extraction apparatus according to claim 1, further comprising a microbubble generating device for generating microbubbles in the heated test water.

6. 2. The odorant extraction device according to claim 1, wherein the test water is heated to 80° C. or higher in the heater.

7. The calculation device calculates the odorant concentration in the test water flowing into the heater by the following formula, where c is the flow rate of the odorant-containing gas, d is the odorant concentration in the odorant-containing gas, b is the flow rate of the test water flowing into the heater, x is the odorant concentration in the test water after the odorant is extracted, a is the odorant concentration in the test water before the odorant is extracted, and H is the dimensionless Henry's constant of the odorant: a=(b+cH) / (bx) x = d / H 2. The odorant extraction device according to claim 1.

8. The calculation device calculates the odorant concentration in the test water that has flowed into the filtration membrane by the following formula, where c is the flow rate of the odorant-containing gas, d is the odorant concentration in the odorant-containing gas, b is the flow rate of the test water flowing into the heater, b' is the flow rate of the test water supplied to the filtration membrane, x is the odorant concentration in the test water after the odorant extraction, a is the odorant concentration in the test water before the odorant extraction, a' is the odorant concentration in the test water supplied to the filtration membrane, f is the permeability of the filtration membrane, and H is the dimensionless Henry's constant of the odorant: a' = a x (1 - f) a=(b+cH) / (bx) x = d / H 3. The odorant extraction device according to claim 2.

9. 9. The odorant extraction device according to claim 7, wherein the dimensionless Henry's constant of the odorant is a value preset according to an extraction temperature of the odorant.

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