JP2020032321A - Ion removal system - Google Patents

Abstract

To provide an ion removal system excellent in maintainability and environmental friendliness.SOLUTION: There is provided an ion removal system which comprises a deaerator for deaerating carbon dioxide contained in hard water, a hard water storage part for storing the hard water in which carbon dioxide is deaerated by the deaerator, a fine bubble generation part for generating fine bubbles to supply the fine bubbles to the hard water storage part and an ion removal apparatus in which metal ions in the hard water are adsorbed by fine bubbles in the hard water storage part and metal ions are removed from hard water.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an ion removal system.

  BACKGROUND ART Conventionally, an ion removal system for removing metal ions in hard water has been disclosed (for example, see Patent Document 1).

  The ion removal system of Patent Literature 1 removes metal ions (calcium ions and magnesium ions) in hard water with an ion exchange resin. Specifically, by flowing hard water into a treatment tank containing an ion-exchange resin having sodium ions adhered to the surface, metal ions in the hard water are replaced with sodium ions, and the metal ions are removed from the hard water. Thereby, the hardness of the hard water is reduced to generate soft water. The metal ions existing in the hard water are captured on the surface of the ion exchange resin.

JP-A-2000-140840

  However, in the ion removal system of Patent Literature 1, a large amount of salt water is required to regenerate the ion-exchange resin capturing the metal ions, and there is a problem that maintenance is troublesome. Further, when the regeneration treatment is performed, there is a problem that regeneration wastewater containing a large amount of salt water is generated, and the load of soil pollution and sewage treatment increases. Furthermore, the treated water softened by the ion removing device has a high concentration of sodium ions, and may not be recommended as drinking water in some areas.

  As described above, the ion removal system using the ion exchange resin has room for improvement in terms of maintainability and environmental friendliness.

  Therefore, an object of the present invention is to solve the above-mentioned problems, and to provide an ion removal system excellent in maintainability and environment.

In order to achieve the above object, an ion removal system according to the present invention comprises:
A degassing device for degassing carbon dioxide contained in hard water,
A hard water storage unit that stores hard water in which carbon dioxide has been degassed by the deaerator, and a fine bubble generation unit that generates fine bubbles and supplies the hard water to the hard water storage unit. An ion removal device that removes metal ions from hard water by adsorbing metal ions to the microbubbles,
Is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the ion removal system excellent in maintainability and environmental characteristics can be provided.

Schematic diagram of the ion removal system of the first embodiment Schematic diagram for explaining a hypothetical principle of degassing of carbon dioxide by the ion removal system of the first embodiment. Schematic diagram for explaining the hypothetical principle of metal ion adsorption by the ion removal system according to the first embodiment. Schematic diagram for explaining the hypothetical principle of crystallization of metal ions by the ion removal system according to the first embodiment. Schematic diagram for explaining a hypothetical principle of a regeneration process by the ion removal system according to the first embodiment. The figure which shows the schematic structure of the apparatus used in the experimental example 1 Graph showing the results of Experimental Example 1 It is a figure which shows the schematic structure of the apparatus used in the example 2 of an experiment, and shows the state after predetermined time passage after generating a microbubble. FIG. 8B is a diagram illustrating a schematic configuration of an apparatus used in Experimental Example 2, showing a state after a predetermined time has elapsed from the state illustrated in FIG. Diagram showing the results of Experimental Example 2 Schematic diagram for explaining the hypothetical principle of metal ion adsorption by the ion removal system according to the second embodiment. Schematic diagram for explaining the hypothetical principle of crystallization of metal ions by the ion removal system according to the second embodiment. Schematic diagram for explaining the hypothetical principle of degassing carbon dioxide by bubbling Schematic diagram for explaining the hypothetical principle of metal ion adsorption by the ion removal system according to the third embodiment. Schematic diagram for explaining the hypothetical principle of metal ion adsorption and crystallization by the ion removal system according to the third embodiment. The figure which shows the schematic structure of the apparatus used in Experimental example 3-5. Diagram showing the state in which metal components are crystallized in hard water 7 is a graph showing the results of Experimental Example 3, and showing the relationship between the mixing ratio of ammonia and the crystallization ratio of sample water. 9 is a graph showing the results of Experimental Example 3, and showing the relationship between the pH of the sample water and the crystallization ratio of the sample water. 9 is a graph showing the results of Experimental Example 4, and showing the relationship between the operation time of the pump and the crystallization ratio of the sample water. 10 is a graph showing the results of Experimental Example 4 and showing the relationship between the operating time of the pump and the Ca hardness of the sample water. 9 is a graph showing the results of Experimental Example 4, and showing the relationship between the operating time of the pump and the pH of the sample water. It is a graph which shows the result of example 5 of an experiment, and is a graph which shows the relation between the operation time of a pump, and the crystallization rate of sample water. It is a graph which shows the result of example 5 of an experiment, and is a graph which shows the relation between the operating time of a pump, and Ca hardness of sample water. It is a graph which shows the result of example 5 of an experiment, and is a graph which shows the relation between operating time of a pump and pH of sample water. It is a graph which shows the result of example 5 of an experiment, and is a graph which shows the operation time of a pump, the Ca hardness of sample water, and the total carbon dioxide concentration. It is a graph which shows the result of example 6 of an experiment, and is a graph which shows the relation between the kind of water and the height of the bubble which extends from the water surface of evaluation water. 12 is a graph showing the results of Experimental Example 7 and showing the relationship between time and the crystallization ratio of Ca hardness. FIG. 14 is a view showing the results of Experimental Example 7, and is a graph showing the relationship between time and the crystallization ratio of total hardness.

  The present inventors have conducted intensive studies and as a result, in ion removal technology (softening technology) for removing metal ions from hard water, removal of metal ions can be promoted by using “fine bubbles” that have not been used conventionally. And found the following invention.

An ion removal system according to one embodiment of the present invention includes:
A degassing device for degassing carbon dioxide contained in hard water,
A hard water storage unit that stores hard water in which carbon dioxide has been degassed by the deaerator, and a fine bubble generation unit that generates fine bubbles and supplies the hard water to the hard water storage unit. An ion removal device that removes metal ions from hard water by adsorbing metal ions to the microbubbles.

  According to this configuration, since the metal ions are removed from the hard water using the fine bubbles, a large amount of salt water necessary for regenerating the ion exchange resin can be eliminated. As a result, the reproduction process can be simplified and the maintenance can be facilitated. Further, since no regenerated wastewater containing salt water is generated, the load of soil pollution and sewage treatment can be suppressed, and the environmental performance can be improved. Furthermore, since the concentration of sodium ions in the treated water does not increase, the produced treated water can be used as drinking water. Further, by degassing carbon dioxide contained in the hard water, the pH of the hard water can be increased. As a result, it is possible to increase the negative charge existing on the surface of the fine bubbles, increase the adsorption of metal ions by the fine bubbles, and improve the efficiency of removing metal ions.

  The degassing device may be configured to degas carbon dioxide contained in the hard water by spraying hard water in a mist. According to this configuration, carbon dioxide contained in hard water can be degassed with a relatively simple configuration.

  Further, the deaerator may be configured to supply gas into hard water and perform bubbling to degas carbon dioxide contained in the hard water. According to this configuration, carbon dioxide contained in hard water can be degassed with a relatively simple configuration.

  The bubbles generated in the hard water by the bubbling may have a larger average outer diameter than the fine bubbles generated by the fine bubble generating section. According to this configuration, the ratio (gas-liquid ratio) of the bubbles in the hard water can be increased to increase the specific surface area of the bubbles, and the degassing effect of carbon dioxide contained in the hard water can be improved.

  Hereinafter, embodiments 1-3 according to the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a diagram illustrating a schematic configuration of the ion removal system 1 according to the first embodiment.

<Overall configuration>
The ion removal system 1 according to the first embodiment includes a primary flow path 2, an ion removal device 3, a separation device 4, and a secondary flow path 5.

  The primary flow path 2 is connected to the ion removing device 3. The primary flow path 2 is a flow path for supplying hard water to the ion removing device 3. In the first embodiment, a pump P is provided at a connection portion between the primary flow path 2 and the ion removing device 3. The pump P functions to flow the hard water flowing through the primary flow path 2 to the separation device 4 through the ion removal device 3. The drive of the pump P is controlled by the control unit 6.

  The primary side channel 2 is provided with a deaerator 16 for degassing carbon dioxide contained in hard water. By degassing the carbon dioxide contained in the hard water by the deaerator 16, the pH of the hard water can be increased. In the first embodiment, the deaerator 16 is configured to degas carbon dioxide contained in the hard water by spraying hard water in the form of a mist in the air. The principle of increasing the pH of hard water by degassing carbon dioxide will be described in detail later. The drive of the deaerator 16 is controlled by the control unit 6.

  The ion removing device 3 includes a hard water storage unit 3A that stores hard water, and a fine bubble generation unit 3B that generates fine bubbles and supplies the generated bubbles to the hard water storage unit 3A. The ion removing device 3 is a device that removes metal ions from hard water by adsorbing metal ions in hard water to fine bubbles in the hard water storage unit 3A. In the first embodiment, hard water storage unit 3A stores hard water from which carbon dioxide has been degassed by deaerator 16. The microbubble generator 3B is arranged downstream of the pump P in the direction of hard water flow so that gas does not enter the pump P.

In the first embodiment, the metal ion is a calcium ion (Ca ²⁺ ) or a magnesium ion (Mg ²⁺ ). In the first embodiment, the fine bubbles are bubbles having a diameter of 100 μm or less. The microbubbles include microbubbles (having a diameter of, for example, 1 μm or more and 100 μm or less) and nanobubbles (having a diameter of, for example, less than 1 μm). The microbubbles may be bubbles that can be recognized by those skilled in the field of water treatment as having a microscopic bubble diameter. The nanobubbles may be bubbles that can be recognized by those skilled in the field of water treatment as having a nanometer-order bubble diameter. Fine bubbles have properties that are different from ordinary bubbles, such as long residence time in water, difficulty in increasing their diameter as a single bubble, and difficulty in merging with other bubbles, and a large contact area that tends to cause a chemical reaction. Having.

  Note that the fine bubbles may include bubbles having a diameter of 100 μm or more (such as millibubbles) at a small ratio. For example, those having a diameter of 100 μm or less and a proportion of 90% or more may be defined as fine bubbles. In addition to this, a condition that the ratio of the diameter of 60 μm or less is 50% or more and the ratio of the diameter of 20 μm or less is 5% or more may be added. When measuring the diameter of a bubble (bubble diameter), for example, a hard water containing fine bubbles may be directly photographed by a high-speed camera, and the bubble diameter may be calculated by a three-point method by image processing. May be measured by any other method. The timing for measuring the bubble diameter may be any timing as long as the fine bubbles remain. An example of the conditions of the measurement method using the high-speed camera described above is as follows.

High-speed camera: FASTCAM 1024 PCI (Photron Co., Ltd.)
Lens system: Z16 APO (Leica)
Objective lens: Planapo 2.0x (Leica)
Shooting speed: 1000fps
Shutter speed: 1/505000 sec
Image area: 1024 × 1024 pixels (micro bubble shooting area 1.42 mm × 1.42 mm, milli bubble shooting area 5.69 mm × 5.69 mm)
Image processing software: Image-Pro Plus (Media Cybermetrics)

  In the first embodiment, an ion removing gas supply unit 7 and a solubilizer supply unit 8 are connected to the fine bubble generation unit 3B via a gas switching mechanism 9.

  The ion removing gas supply unit 7 is configured to supply an ion removing gas for removing metal ions in hard water to the fine bubble generating unit 3B. In the first embodiment, the ion removing gas supply unit 7 is configured to supply “air” as the ion removing gas to the fine bubble generating unit 3B. The ion removing gas supply unit 7 may include, for example, a tank filled with the ion removing gas. Further, the ion removing gas supply unit 7 may be a device that generates an ion removing gas. Further, the ion removing gas supply unit 7 may be a device connected to an ion removing gas supply source.

The dissolving agent supply unit 8 is configured to supply a dissolving gas, which is an example of a dissolving agent for dissolving the crystal of the metal component precipitated by crystallizing the metal ions removed from the hard water, to the fine bubble generating unit 3B. ing. In the first embodiment, the dissolving agent supply unit 8 is configured to supply “carbon dioxide (CO ₂ )” as a dissolving gas to the fine bubble generation unit 3B. The dissolving agent supply unit 8 is disposed upstream of the separating device 4 in the flow direction of the hard water so that the dissolving agent can be supplied to the separating device 4. The dissolving agent supply unit 8 may include, for example, a tank filled with a dissolving agent. The dissolving agent supply unit 8 may be a device that generates a dissolving agent. Further, the dissolving agent supply unit 8 may be a device connected to a dissolving agent supply source.

  The gas switching mechanism 9 is a mechanism that switches one of the gas for ion removal and the gas for dissolution so as to be supplied to the fine bubble generation unit 3B. By switching the gas switching mechanism 9, the water softening treatment with the ion removing gas and the regeneration treatment with the dissolving gas can be selectively performed. The gas switching mechanism 9 includes, for example, one or more valves. The switching operation of the gas switching mechanism 9 is controlled by the control unit 6.

  When the gas switching mechanism 9 is switched to supply the ion-removing gas, the fine-bubble generating unit 3B generates fine bubbles containing the ion-removing gas. The microbubbles remove the metal ions from the hard water and separate the crystals of the metal component, whereby the hard water is softened. The principle of the water softening treatment will be described later in detail.

  On the other hand, when the gas switching mechanism 9 is switched so that the gas for dissolution is supplied, the microbubble generating unit 3B generates microbubbles containing the gas for dissolution. With the fine bubbles, the crystal of the metal component attached to the separation device 4 can be dissolved and regenerated as described later. The principle of the reproduction process will be described later in detail.

  The separation device 4 is connected to the ion removal device 3 via a connection flow path 3C provided on the upper outer peripheral portion of the hard water storage unit 3A. The separation device 4 is a device that crystallizes metal ions removed from hard water by the ion removal device 3 and separates crystals of a metal component precipitated. The ion removal device 3 and the separation device 4 make it possible to reduce the concentration (hardness) of metal ions in hard water to a predetermined concentration or less, thereby producing soft water. As the definition of hard water and soft water, for example, the definition of WHO may be used. That is, a hardness of less than 120 mg / L may be defined as soft water, and a hardness of 120 mg / L or more may be defined as hard water.

  In the first embodiment, the separation device 4 has a tapered inner peripheral surface 4Aa whose diameter decreases downward, and hard water flows downward along the inner peripheral surface 4Aa in a helical manner. It is a cyclone-type centrifugal separator for separating component crystals. In the first embodiment, the separation device 4 includes a separation unit 4A having an inner peripheral surface 4Aa, and a crystal storage unit 4B for storing crystals of a metal component.

  The connection channel 3C is connected to the separation unit 4A so as to discharge the water that has passed through the ion removing device 3 in a direction eccentric from the central axis of the separation unit 4A. With such an eccentric arrangement, the water discharged into the separation part 4A flows downward spirally along the inner peripheral surface 4Aa. The metal ions having a large specific gravity removed from the hard water move toward the inner peripheral surface 4Aa by centrifugal separation, and precipitate as metal component crystals near the inner peripheral surface 4Aa. Part of the crystal adheres to the inner peripheral surface 4Aa.

  Crystal storage unit 4B is arranged below separation unit 4A. The crystal storage section 4B includes a discharge channel 4Ba for discharging water containing crystals of the metal component. The discharge passage 4Ba is provided with an on-off valve 10 that can open and close the discharge passage 4Ba. The opening and closing operation of the on-off valve 10 is controlled by the control unit 6. A discharge-side backflow prevention mechanism 11 is provided downstream of the on-off valve 10 in the discharge flow path 4Ba in the discharge direction.

  The discharge-side backflow prevention mechanism 11 is a mechanism that prevents the crystal of the metal component from flowing back into the separation device 4. The discharge-side backflow prevention mechanism 11 can prevent the crystal of the metal component from being mixed again into the treated water (soft water) in which the crystal of the metal component is separated from the hard water. The discharge-side backflow prevention mechanism 11 includes, for example, one or more check valves. Further, the discharge-side backflow prevention mechanism 11 may be constituted by, for example, a vacuum breaker. Furthermore, the discharge-side backflow prevention mechanism 11 may be configured to provide a water outlet space at the outlet of the discharge flow path 4Ba to prevent backflow.

  The secondary flow path 5 is connected to the separation device 4. The secondary flow path 5 is a flow path for taking out the treated water from which the crystal of the metal component has been separated from the separation device 4. In the first embodiment, since the separation device 4 is a cyclone-type centrifugal separation device, crystals of the metal component can be collected near the inner peripheral surface 4Aa. In order to suppress the intrusion of the crystal of the metal component into the secondary flow path 5, the secondary flow path 5 is connected to the upper central portion of the separation portion 4A, which is a position away from the inner peripheral surface 4Aa. .

  The treated water flowing through the secondary flow path 5 is supplied to, for example, a kitchen, a bathroom, a toilet, a wash surface, and the like. When the flow rate of the liquid flowing from the primary flow path 2 to the secondary flow path 5 is sharply reduced due to the use of the treated water, the speed of centrifuging metal ions from hard water decreases, and the efficiency of removing metal ions increases. Degradation can occur. Further, it is possible that crystals of the metal component are mixed into the treated water.

  For this reason, in the first embodiment, a part of the treated water in which the crystal of the metal component is separated from the hard water by the separation device 4 is returned to the primary side flow passage 2 in the separation device 4 and the primary flow passage 2. The channel 12 is connected. That is, the primary flow path 2, the ion removing device 3, the separation device 4, and the return flow path 12 constitute a circulation flow path. With this circulation flow path, the fluctuation of the flow rate of the liquid flowing from the primary flow path 2 to the secondary flow path 5 can be further stabilized, and a decrease in the metal ion removal efficiency can be suppressed. In addition, by driving the pump P to forcibly circulate the liquid in the circulation flow path, fluctuations in the flow rate of the liquid can be further stabilized, and a reduction in metal ion removal efficiency can be suppressed. . Further, it is possible to suppress the crystal of the metal component from being mixed into the treated water.

  The flow rate of the liquid flowing through the circulation channel is preferably equal to or higher than the usage flow rate of the soft water (for example, 2 liter / minute). As the flow rate of the liquid flowing through the circulation flow path is larger than the usage flow rate of the soft water, the fluctuation of the flow rate of the liquid is more stabilized, and the soft water can be produced more stably. Further, the circulation channel is preferably a closed system. Thereby, it is possible to suppress the intake of air into the circulation flow path, and to further stabilize the fluctuation of the flow rate of the liquid.

  In the first embodiment, one end 12a of the return flow path 12 is opened on the central axis side of the separation part 4A. This suppresses the crystal of the metal component precipitated near the inner peripheral surface 4 </ b> Aa from entering the return channel 12. The connection channel 3C of the ion removing device 3 is connected to the separation part 4A below the one end 12a of the return channel 12. That is, the one end 12a of the return channel 12 is located above the outlet of the connection channel 3C from which the hard water from which the metal ions have been removed is spirally discharged downward. This further suppresses the crystal of the metal component precipitated near the inner peripheral surface 4 </ b> Aa from entering the return channel 12.

  Further, a supply side backflow prevention mechanism 13 is provided in the primary side flow path 2. The supply-side backflow prevention mechanism 13 is a mechanism for preventing fine bubbles and treated water from flowing back to the hard water supply side. The supply-side backflow prevention mechanism 13 includes, for example, one or more check valves. In the first embodiment, the supply-side backflow prevention mechanism 13 is provided upstream of the return flow path 12 in the flow direction of the hard water in the primary flow path 2. Thereby, it is possible to more reliably prevent the fine bubbles, the treated water and the like from flowing back to the hard water supply side.

  Further, for example, when maintenance is required due to a failure of the ion removing device 3, water cannot be used during the maintenance. Therefore, in the first embodiment, the primary flow path 2 and the secondary flow path 5 are connected by the bypass flow path 14. In addition, the ion removal system 1 includes a flow switching mechanism that switches the flow direction of the hard water flowing through the primary flow path 2 toward one of the ion removal device 3 and the bypass flow path 14. By switching the flow switching mechanism, the hard water flowing in the primary flow path 2 can flow to the secondary flow path 5 through the bypass flow path 14, so that the hard water can be used even during maintenance. Further, even during maintenance, by switching the flow switching mechanism, it is possible to selectively use hard water and treated water (soft water).

  In the first embodiment, the flow switching mechanism can open and close a first valve 15A that can open and close the primary flow path 2, a second valve 15B that can open and close the secondary flow path 5, and can open and close the bypass flow path 14. And a third valve 15C. The opening and closing operations of the first valve 15A, the second valve 15B, and the third valve 15C are controlled by the control unit 6.

  The control unit 6 opens the first valve 15A and the second valve 15B and closes the third valve 15C, and closes the first valve 15A and the second valve 15B and opens the third valve 15C. The second control is selectively executed. When the control unit 6 executes the first control, the hard water flowing in the primary flow path 2 flows to the ion removing device 3 to be softened, and flows into the secondary flow path 5. Thereby, the treated water (soft water) is discharged to the outlet of the secondary flow path 5. When the control unit 6 executes the second control, the hard water flowing through the primary flow path 2 flows into the secondary flow path 5 through the bypass flow path 14. As a result, hard water is discharged from the outlet of the secondary channel 5. That is, when the control unit 6 performs the first control or the second control, it is possible to selectively discharge hard water or treated water (soft water) from the outlet of the secondary flow path 5.

<Increase in pH due to degassing>
Next, the principle of increasing the pH of hard water by degassing carbon dioxide from hard water will be described in more detail.

As shown in FIG. 2, hard water contains at least H ⁺ (hydrogen ions), OH ⁻ (hydroxide ions), CO ₂ (carbon dioxide), H ₂ CO ₃ (hydrogen carbonate), and HCO ₃ ⁻ (hydrogen carbonate). Ions) and H ₂ O (water). When the hard water is sprayed in the form of a mist, the surface area of the hard water that comes into contact with the air increases, so that CO ₂ contained in the hard water escapes into the air. Thus, CO ₂ is reduced in hard water.

In order to compensate for the reduced CO ₂ , H ₂ CO _{3 in} hard water changes to CO ₂ and H ₂ O due to a buffering action. As a result, H ₂ CO ₃ in hard water is reduced. When expressed by a specific chemical formula, the following formula 1 is obtained.

(Equation 1)
H ₂ CO ₃ → CO ₂ + H ₂ O

In order to compensate for the reduced H ₂ CO ₃ , HCO ₃ ^{− in} hard water binds to H ⁺ and changes to H ₂ CO ₃ by buffering action. When expressed by a specific chemical formula, it is as the following formula 2.

(Equation 2)
HCO ₃ ⁻ + H ⁺ → H ₂ CO ₃

At this time, the consumption of H ⁺ increases the pH of the hard water. Such a buffering action is repeated until an equilibrium state is reached. In addition, it is possible to raise the pH of hard water to about 8.5 by this deaeration treatment, for example.

<Softening treatment>
Next, the principle of the water softening treatment using fine bubbles will be described in more detail.

  It is presumed that the action as described in the following columns (1) and (2) occurs on metal ions in hard water by supplying microbubbles containing air into hard water. Specifically, it is presumed that the metal ions in the hard water are adsorbed to the fine bubbles and the adsorbed metal ions are crystallized, so that the crystal of the metal component can be removed from the hard water. More specifically, it is as follows. It should be noted that the present invention is not limited to the specific principles described in the following sections (1) and (2).

(1) Adsorption of Metal Ions As shown in FIG. 2, when microbubbles including air are supplied into hard water, H ⁺ (hydrogen ions) and OH ⁻ (hydroxide ions) are formed on the surfaces of the microbubbles. H ⁺ is charged to a positive charge and OH ⁻ is charged to a negative charge (FIG. 2 shows only OH ⁻ ). On the other hand, in hard water, Ca ²⁺ and Mg ²⁺ exist as positively charged metal ions. In the following description, Ca ²⁺ will be described as an example of the metal ion.

Ca ²⁺ having a positive charge is adsorbed on OH ⁻ existing on the surface of the microbubbles by the action of intermolecular force (interionic interaction). Thus, Ca ²⁺ can be adsorbed by the fine bubbles. Although H ⁺ repelling Ca ²⁺ is present on the surface of the fine bubbles, it is considered that OH ⁻ acts preferentially over H ⁺ to adsorb Ca ²⁺ . This “adsorption of metal ions” is mainly performed in the ion removing device 3.

In the first embodiment, the pH of the hard water is increased by degassing. As the pH of the hard water increases, the amount of negatively charged OH ⁻ present on the surface of the fine bubbles increases, and Ca ²⁺ is easily adsorbed by the fine bubbles. As a result, crystallization of metal ions can be promoted as described later.

(2) Crystallization of metal ions In addition to the reaction shown in FIG. 3, by supplying microbubbles containing air into hard water, the reaction shown in FIG. 4 is promoted. Specifically, fine bubbles supplied into hard water are unlikely to float unlike ordinary bubbles, and are dissolved in hard water, so that the surface tension increases and gradually contracts as shown in FIG. To go. As described above, Ca ²⁺ is adsorbed on the surface of the fine bubbles. More specifically, it is present as calcium ions of soluble Ca (HCO ₃ ) ₂ (calcium hydrogen carbonate). Here, as the fine bubbles gradually contract, the dissolved concentration of Ca ^{2+ on} the surface of the fine bubbles increases. Due to an increase in the dissolution concentration, a supersaturation state is reached at some point, and Ca ²⁺ crystallizes and precipitates. The specific chemical formula is as shown in the following formula 3.

(Equation 3)
Ca (HCO ₃ ) ₂ → CaCO ₃ + CO ₂ + H ₂ O

Since CaCO ₃ (calcium carbonate) is insoluble (insoluble in water), it precipitates as crystals of the metal component. As a result, Ca (HCO ₃ ) ₂ dissolved as Ca ²⁺ is precipitated as crystals of the metal component. By promoting such a reaction, CaCO ₃ precipitated by crystallization of Ca ²⁺ of metal ions from hard water can be separated. This “crystallization of metal ions” is mainly performed in the separation section 4A of the separation device 4.

  In addition, although the reaction in the opposite direction to the expression 3 may occur in the same water, it is presumed that the reaction in the direction of the expression 3 is preferentially performed in the equilibrium relationship by continuously supplying fine bubbles. Is done.

  In the first embodiment, since the separation device 4 is a cyclone-type centrifugal separation device, the crystal of the metal component precipitates near the inner peripheral surface 4Aa of the separation unit 4A and is stored in the crystal storage unit 4B. The crystal of the metal component stored in the crystal storage unit 4B is discharged through the discharge flow path 4Ba when the on-off valve 10 is opened. In this way, the hard water can be softened by separating the crystal of the metal component from the hard water.

<Playback processing>
Next, the principle of the regeneration process using fine bubbles will be described in more detail.

By performing the water softening treatment, a part of CaCO ₃ crystallized and precipitated from the metal ions adheres to the inner peripheral surface 4Aa of the separation part 4A. As a process for returning the CaCO ₃ to Ca (HCO ₃ ) ₂ , a regeneration process is performed. Specifically, the microbubble generator 3B generates microbubbles containing carbon dioxide, which is a different gas from that used during the water softening treatment.

As shown in FIG. 5, the following reaction is promoted by supplying fine bubbles of carbon dioxide to CaCO ₃ attached to the inner peripheral surface 4Aa of the separation unit 4A.

(Equation 4)
CaCO ₃ + CO ₂ + H ₂ O → Ca (HCO ₃ ) ₂

By this reaction, soluble (water-soluble) Ca (HCO ₃ ) ₂ is produced from insoluble CaCO ₃ . Ca (HCO ₃ ) ₂ dissolves into the water and moves to the crystal storage unit 4B. The Ca (HCO ₃ ) _{2 that} has moved to the crystal storage unit 4B is discharged through the discharge flow path 4Ba when the on-off valve 10 is opened. Thereby, the insoluble CaCO ₃ adhered to the inner peripheral surface 4Aa of the separation portion 4A can be discharged to the outside and returned to the original state. Thereafter, the water softening treatment described above can be performed again.

Although Ca ²⁺ has been described as an example of the metal ion in the above description, it is assumed that the same reaction occurs with Mg ²⁺ .

  As described above, when metal ions are removed from hard water using an ion exchange resin, a large amount of salt water is required to regenerate the ion exchange resin. On the other hand, according to the ion removal system 1 of the first embodiment, metal ions are removed from hard water using fine bubbles, so that a large amount of salt water required for regenerating the ion exchange resin is unnecessary. be able to. As a result, the reproduction process can be simplified and the maintenance can be facilitated. Further, since no regenerated wastewater containing salt water is generated, the load of soil pollution and sewage treatment can be suppressed, and the environmental performance can be improved. Furthermore, since the concentration of sodium ions in the treated water does not increase, the produced treated water can be used as drinking water. Further, by degassing carbon dioxide contained in the hard water, the pH of the hard water can be increased. As a result, it is possible to increase the negative charge existing on the surface of the fine bubbles, increase the adsorption of metal ions by the fine bubbles, and improve the efficiency of removing metal ions.

  In addition, according to the ion removal system 1 of the first embodiment, since air is used as the ion removal gas, the cost of generating fine bubbles can be extremely reduced.

Further, according to the ion removal system 1 of the first embodiment, after removing metal ions from hard water, a regeneration process is performed by supplying fine bubbles of carbon dioxide as a gas for dissolution. Thereby, the reaction of producing soluble Ca (HCO ₃ ) ₂ from insoluble CaCO ₃ can be promoted, and the regeneration treatment can be promoted.

(Experimental example 1)
Next, Experimental Example 1 performed to confirm the principle of the increase in pH due to degassing will be described. Here, an experiment was performed using the apparatus shown in FIG.

  FIG. 6 is a diagram illustrating a schematic configuration of the device 90 used in the first experimental example.

  As shown in FIG. 6, the device 90 includes a water tank 91, a first pipe 92, a pump 93, a second pipe 94, and a mist nozzle 95.

  The water tank 91 is a water tank that stores the hard water 96. The water tank 91 is connected to a pump 93 via a first pipe 92. The pump 93 is connected to the mist nozzle 95 via the second pipe 94. The mist nozzle 95 is provided at a position away from the sample 97 by a mist distance H1. The pump 93 is a pump that pumps hard water 96 to the mist nozzle 95. The mist nozzle 95 is a nozzle that sprays hard water supplied through the second pipe 94 toward the sample 97 in a mist shape. The residual water remaining in the water tank 91 is drained to the outside by opening an on-off valve 98 provided in the first pipe 92.

  FIG. 7 is a graph showing the results of Experimental Example 1. Here, as the mist nozzle 95, three nozzles 1, 2, and 3 having different mist diameters (average outer diameter of mist) are used. Specifically, the nozzle 1 is a nozzle that injects a mist having a mist diameter of 290 μm and an instantaneous flow rate of 1.3 L / min. The nozzle 2 is a nozzle that sprays a mist having a mist diameter of 760 μm and an instantaneous flow rate of 4.2 L / min. The nozzle 3 is a nozzle that sprays a mist having a mist diameter of 2500 μm and an instantaneous flow rate of 0.2 L / min.

  In FIG. 7, the horizontal axis represents the mist distance H1 (mm), and the vertical axis represents the pH of the hard water 96. As shown in FIG. 7, it was confirmed that the smaller the mist diameter, that is, the larger the specific surface area, the higher the pH of the hard water 96. Further, it was confirmed that the longer the mist distance H1 was, the longer the time during which the hard water 96 was in contact with the air was, so that the pH of the hard water 96 generally increased.

(Experimental example 2)
Next, a description will be given of Experimental Example 2 performed to confirm the principle of water softening treatment using fine bubbles. Here, an experiment was performed using the device 20 shown in FIGS. 8A and 8B.

  8A and 8B are diagrams illustrating a schematic configuration of the device 20 used in Experimental Example 2. FIG. FIG. 8A shows a state after a lapse of a predetermined time (specifically, after a lapse of 15 seconds) from the generation of fine bubbles, and FIG. 8B shows a state after a lapse of a predetermined time from the state shown in FIG. 8A (specifically, (After 45 seconds). The state of FIG. 8A corresponds to the state in which the elapsed time since the generation of the fine bubbles in FIG. 9 is 15 seconds, and the state of FIG. 8B corresponds to the state in which the elapsed time since the generation of the fine bubbles in FIG. 9 is 60 seconds.

  The apparatus 20 shown in FIGS. 8A and 8B is an experimental apparatus capable of supplying microbubbles 23 from the bottom side in a water tank 22 (hard water storage unit) storing hard water 21. In the device 20, the concentration of metal ions in the hard water 21 can be measured at two places, that is, the bottom surface side and the water surface side. The microbubbles 23 were supplied into the water tank 22 using such an apparatus 20, and the transition of the concentration of metal ions on the bottom surface side and the water surface side was detected. The result shown in FIG.

  From the results shown in FIG. 9, the above-described effect of “adsorption of metal ions by fine bubbles” was able to be demonstrated. Specific results will be described later.

  As shown in FIGS. 8A and 8B, the apparatus 20 includes a water tank 22, a gas supply unit 24, a first pipe 25, a fine bubble generation unit 26, a second pipe 27, a pump 28, and a first water intake unit. 30, a second water intake unit 32, and a metal ion concentration detector 34.

  The water tank 22 is a water tank that stores the hard water 21. 8A and 8B, the water tank 22 is configured as a tank that is long in the vertical direction. The gas supply unit 24 is a member that supplies gas to the fine bubble generation unit 26 via the first pipe 25. The fine bubble generation unit 26 is a device that generates the fine bubbles 23 based on the gas supplied from the gas supply unit 24. The fine bubble generator 26 corresponds to the fine bubble generator 3B described above. The supply of gas from the gas supply unit 24 to the fine bubble generation unit 26 is performed by a negative pressure action via a second pipe 27 by a pump 28.

  The first water intake section 30 is a member that takes in the sample water of the hard water 21 from near the bottom surface 22 a of the water tank 22. The second water intake section 32 is a member that takes in sample water from near the water surface 22 b of the water tank 22. The height position of the first water intake unit 30 and the second water intake unit 32 may be set at any position, and the distance D1 from the first water intake unit 30 to the second water intake unit 32 may be adjusted to a desired value. it can.

  In the example shown in FIGS. 8A and 8B, the height position of the first water intake unit 30 is set to be substantially the same as the height position at which the microbubble generating unit 26 generates the microbubbles 23.

  The metal ion concentration detector 34 is a member that detects the concentration of metal ions in the sample water taken from the first water intake unit 30 and the second water intake unit 32.

  When the microbubble generator 26 and the pump 28 are operated in the above configuration, the gas is supplied from the gas supply unit 24 to the microbubble generator 26 via the first pipe 25 by the negative pressure effect of the pump 28 via the second pipe 27. Sent. Using this gas as a raw material, the fine bubble generator 26 generates fine bubbles 23 and supplies them to the water tank 22 (arrow A1 in FIG. 8A).

  The microbubble generating section 26 and the pump 28 are operated for a predetermined period (15 seconds in Experimental Example 2) to continuously generate the microbubbles 23.

  Thereafter, the operations of the fine bubble generation unit 26 and the pump 28 are stopped. After the operation is stopped, a predetermined rest period is provided (45 seconds in Experimental Example 2).

  As shown in FIG. 8A, at the end of the operation period (15 seconds after the generation of microbubbles), the microbubbles 23 supplied into the water tank 22 rise in the hard water 21 (arrow A2), and It was visually confirmed that it had stayed in the lower part.

  As shown in FIG. 8B, at the end of the rest period (60 seconds after the generation of microbubbles), the microbubbles 23 supplied into the hard water 21 further rise and reach the water surface 22b (arrow A3), and the water tank It was visually confirmed that the stagnation stayed in the upper part of 22.

  FIG. 6 shows the result of taking out sample water from the first water intake unit 30 and the second water intake unit 32 at a predetermined timing during the operation, and measuring the metal ion concentration by the metal ion concentration detector 34.

  Specific experimental conditions for the results of FIG. 9 are described below.

(Experimental conditions)
Type of gas supplied by gas supply unit 24: air Hardness of hard water 21: about 300 mg / L
Temperature of hard water 21: 25 ° C
Distance D1 from first water intake unit 30 to second water intake unit 32: about 1 m
Operation period of the microbubble generator 26 and the pump 28: 15 seconds Rest period of the microbubble generator 26 and the pump 28: 45 seconds Metal ion concentration detector 34: LAQUA F-70 manufactured by HORIBA, Ltd.
Metal ion to be measured: Ca ²⁺
Sample water removal timing: 0, 15, 30, 30 or 60 seconds after the start of operation

In FIG. 9, the horizontal axis represents the elapsed time (seconds) from the generation of the microbubbles, and the vertical axis represents the concentration transition (%) of the metal ion (Ca ²⁺ ) detected by the metal ion concentration detector 34. The transition of the concentration of the metal ion represents the transition of the concentration of the metal ion when the concentration of the metal ion measured at the start of the operation is 100%.

  As shown in FIG. 9, the concentration of the sample water extracted from the first water intake unit 30 near the bottom surface 22a of the water tank 22 has increased to about 108% after 15 seconds. During the rest period, it gradually decreases, and eventually decreases to about 97%.

  On the other hand, the concentration of the sample water extracted from the second water intake section 32 in the vicinity of the water surface 22b of the water tank 22 is maintained at almost 100% until the lapse of 15 seconds, and then gradually increases during the rest period, and finally increases. Has gradually increased to about 115%.

  The result of the change in the concentration of the metal ions and the behavior of the microbubbles 23 are as follows.

  At the lapse of 15 seconds shown in FIG. 8A, the metal ion concentration has increased in the sample water of the first water intake section 30 in which the fine bubbles 23 are retained. On the other hand, in the sample water of the second water intake section 32 in which the fine bubbles 23 do not stay, the metal ion concentration hardly changes.

  At the elapse of 60 seconds shown in FIG. 8B, the metal ion concentration in the sample water of the first water intake unit 30 in which the fine bubbles 23 are not retained has decreased to slightly less than 100%. On the other hand, in the sample water of the second water intake section 32 in which the fine bubbles 23 are retained, the metal ion concentration is significantly increased.

According to such a result, it is presumed that Ca ^2+, which is a metal ion in the hard water 21, is adsorbed by the fine bubbles 23 and increases together with the rise of the fine bubbles 23.

  Based on the above presumption, the effect of the above-mentioned "adsorption of metal ions by fine bubbles" could be demonstrated.

(Embodiment 2)
Second Embodiment An ion removal system according to a second embodiment of the present invention will be described. In the second embodiment, differences from the first embodiment will be mainly described. In the second embodiment, the same or equivalent components as those in the first embodiment are denoted by the same reference numerals and described. In the second embodiment, descriptions overlapping with the first embodiment are omitted.

  The second embodiment is different from the first embodiment in that nitrogen is used instead of air as gas of fine bubbles in the water softening treatment.

  By generating nitrogen microbubbles from the microbubble generating unit 3B and supplying it to hard water, in addition to the above-described operations of “(1) adsorption of metal ions” and “(2) crystallization of metal ions”, It is assumed that the effects described in the following sections (3) and (4) are promoted. In addition, it is not necessarily restricted by the specific principle described in the following columns (3) and (4).

(3) Promotion of adsorption of metal ions As shown in FIG. 10A, H ⁺ and OH ⁻ are charged around the microbubbles. As described above, the positively charged Ca ²⁺ is adsorbed on the negatively charged OH ⁻ . Under such circumstances, when nitrogen is used as the microbubbles, the reaction of the following formula 5 is promoted.

(Equation 5)
N ₂ + 6H ⁺ + 6e ⁻ → 2NH ₃
NH ₃ + H ₂ O → NH ₄ ⁺ + OH ⁻

By promoting the reaction of Formula 5, as shown in FIG. 10B, the number of H ⁺ ions is reduced with respect to the number of OH ⁻ ions. As a result, the negative charge becomes stronger as fine bubbles, and Ca ²⁺ having a positive charge is easily adsorbed.

  In the case where nitrogen is used as in the second embodiment, the reaction of the above formula 5 can be promoted as compared with the case where air is used as in the first embodiment, so that the adsorption of metal ions is further promoted. . Thereby, more metal ions can be separated and removed from hard water.

Note that the above principle is not limited to nitrogen, and it is presumed that the same applies to any gas that can react with H ⁺ ions and reduce the number of H ⁺ ions with respect to the number of OH ⁻ ions.

(4) Acceleration of crystallization of metal ions Since nitrogen is an inert gas different from air, when supplied into hard water, the partial pressure of the gas contained in the hard water is imbalanced. . Thereby, the reaction as shown in FIG. 11 is promoted.

As shown in FIG. 11, another gas component dissolved in hard water acts on microbubbles composed of nitrogen to replace them. In the example shown in FIG. 11, it includes a CO ₂ to Ca _{(HCO 3) 2} which is present around the fine bubbles act tries Okikawaro this CO ₂ is extracted to the nitrogen. That is, the following reactions are promoted.

(Equation 6)
Ca (HCO ₃ ) ₂ → CaCO ₃ + CO ₂ + H ₂ O

In this way, a reaction occurs in which soluble Ca (HCO ₃ ) ₂ generates insoluble CaCO ₃ . At this time, CO ₂ and H ₂ O are generated. Since CaCO ₃ is insoluble, it precipitates as crystals of the metal component.

By the above reaction, metal ions contained as Ca ²⁺ of Ca (HCO ₃ ) ₂ in hard water can be crystallized and precipitated. Thereby, the crystal of the metal component can be removed from the hard water.

  Note that the above principle is not limited to nitrogen, and it is presumed that the same applies to any gas other than air that disrupts the balance of the partial pressure of the gas dissolved in hard water.

  As described above, in the second embodiment, nitrogen is taken in to generate microbubbles and supplied into hard water, so that “(3) promotion of metal ion adsorption” can be achieved as compared with the case of using air, The reaction described in the section of “(4) Promotion of crystallization of metal ions” can be promoted. Thereby, the accuracy of removing metal ions from hard water can be improved.

  In the first embodiment, the deaerator 16 is configured to degas carbon dioxide contained in the hard water by spraying hard water in the form of mist in the air. The invention is not limited to this. For example, the deaerator 16 may be configured to degas carbon dioxide contained in the hard water by spraying hard water in a mist state in a nitrogen atmosphere. According to this configuration, the carbon dioxide in the hard water acts to replace the nitrogen, so that the carbon dioxide easily escapes from the hard water. Thereby, the degassing efficiency of carbon dioxide can be improved.

  The deaerator 16 may be configured to degas carbon dioxide contained in the hard water by, for example, supplying a gas into the hard water and bubbling the gas. In this case, it is preferable to use a gas having a low concentration of carbon dioxide, for example, air as the gas. Further, as the gas, it is more preferable to use a gas that does not contain carbon dioxide, for example, nitrogen. According to this configuration, as shown in FIG. 12, nitrogen in bubbles generated by bubbling in hard water acts to replace carbon dioxide contained in hard water, and carbon dioxide escapes from hard water. It will be easier. Thereby, the degassing efficiency of carbon dioxide can be improved.

  Note that bubbles generated in hard water by bubbling may have a larger average outer diameter than the fine bubbles generated by the fine bubble generating unit 3B. For example, bubbles generated in hard water by bubbling may be millibubbles (having a diameter of 1 mm or more and 10 mm or less). Millibubbles may be air bubbles that can be recognized by those skilled in the field of water treatment as having a diameter on the order of millimeters. According to this configuration, the ratio of air bubbles (gas-liquid ratio) in hard water can be increased (for example, from several percent to 50%) to increase the specific surface area of air bubbles, and the removal of carbon dioxide contained in hard water can be improved. Qi effect can be improved.

  In addition, as a method of degassing carbon dioxide contained in hard water, there are a film degassing method, a vacuum degassing method, and a heating degassing method, in addition to the stripping method and the bubbling method of spraying the mist described above. The carbon dioxide contained in the hard water may be degassed using an apparatus utilizing these degassing methods. However, an apparatus using the above-described stripping method or bubbling method can degas carbon dioxide contained in hard water with a relatively simple configuration.

(Embodiment 3)
A method for removing metal ions by the ion removal system according to the third embodiment of the present invention will be described. In the third embodiment, differences from the first and second embodiments will be mainly described, and descriptions overlapping with the first and second embodiments will be omitted.

  In Embodiments 1 and 2, the microbubble generating section 3B generates microbubbles including air, whereas Embodiment 3 generates microbubbles including a mixed gas obtained by mixing a plurality of types of gases. However, this is different from the first and second embodiments.

  In the third embodiment, the mixed gas for generating fine bubbles includes a first gas that is a basic gas and a second gas that is a gas having a dissolution rate lower than that of the first gas. A mixture of different gases is used. That is, the ion removing gas supply unit 7 shown in FIG. 1 supplies a mixed gas obtained by mixing the first gas and the second gas to the fine bubble generating unit 3B as the ion removing gas.

  By generating microbubbles using a mixed gas containing the first gas and the second gas, in addition to the above-described operations of “(1) adsorption of metal ions” and “(2) crystallization of metal ions”, It is presumed that the effects described in the following sections (5) and (6) are promoted. In addition, it is not necessarily restricted by the specific principle described in the following columns (5) and (6).

(5) Change in potential on the surface of microbubbles due to first gas The first gas contained in the mixed gas is a basic gas that receives H ⁺ by an acid-base reaction. The first gas is dissolved in water to generate OH ⁻ . Specifically, the reaction of the following formula 7-1 is caused.

(Equation 7-1)
^{_{X + H 2 O → XH +}} + OH -

In the formula 7-1, the first gas is represented by the chemical formula X. As a result of the reaction of Equation 7-1, as shown in FIG. 13, the ratio of OH ⁻ present around the microbubbles 40 increases as compared with the ratio of H ⁺ (in FIG. 13, H ⁺ is illustrated). Omitted). Solid - potential of the interface of the liquid is water H + / OH ^- is strongly dependent pH of water quality for the potential decision ions, H ⁺ increases the positive charge becomes strong, OH ^- it increases the negative charges Become stronger. As a result, the negative charge of the microbubbles 40 becomes stronger, and Ca ²⁺ having a positive charge is easily adsorbed. In this manner, the metal ion adsorption effect of the fine bubbles 40 can be improved.

  Further, in Embodiment 3, the basic gas ammonia is used as the first gas. When ammonia is used, the above equation 7-1 is embodied in the following equation 8.

(Equation 8)
NH ₃ + H ₂ O → NH ₄ ⁺ + OH ⁻

  By generating the microbubbles 40 using ammonia, which is a general gas having high solubility in water, the cost of generating the microbubbles 40 can be reduced while improving the metal ion adsorption effect described above.

  It is assumed that the above principle is not limited to ammonia but applies to any basic gas. Examples of such a basic gas include methylamine, ethylamine, propylamine, isopropylamine, butylamine, hexylamine, cyclohexylamine, dimethylamine, diethylamine, diisopropylamine, dipropylamine, di-n-butylamine, ethanolamine, Diethylethanolamine, dimethylethanolamine, ethylenediamine, dimethylaminopropylamine, N.P. Examples include N-dimethylethylamine, trimethylamine, triethylamine, tetramethylenediamine, diethylenetriamine, propyleneimine, pentamethylenediamine, hexamethylenediamine, morpholine, N-methylmorpholine, and N-ethylmorpholine.

In addition, as shown in Formula 7-1, X is not limited to a basic gas, and the same applies to a “hydroxyl ion donor gas” that reacts with water (H ₂ O) to provide a hydroxyl ion (OH ⁻ ). It is considered to be effective. Examples of the hydroxyl group ion donating gas include soluble ozone gas (O ₃ ). When the ozone gas is supplied to water, it is considered that a reaction represented by the following formula 7-2 similar to the formula 7-1 occurs.

(Equation 7-2)
O ₃ + H ₂ O + 2e ⁻ → O ₂ + 2OH ⁻

  According to the formula 7-2, it is considered that the hydroxyl ion donating gas “X” that causes the reaction shown in the following formula 7-3 also exerts the same effect.

(Equation 7-3)
XO + H ₂ O + 2e ⁻ → X + 2OH ⁻

  The ozone will be described in Experimental Example 7.

(6) Maintenance of Fine Bubbles by Second Gas As described in the section of “(5) Change in potential of microbubble surface by first gas”, first gas which is a basic gas contained in the mixed gas Dissolves in water to increase the proportion of OH ^{− on} the surface of the microbubbles 40. Such a first gas is mixed with a second gas, which is a gas having a lower dissolution rate than the first gas. By mixing such a second gas, even if the first gas is dissolved in water, the entirety of the fine bubbles 40 is prevented from being dissolved in water, and the state of the fine bubbles 40 can be maintained. By maintaining the state of the microbubbles 40, the effect of adsorbing Ca ²⁺ ions derived from the microbubbles described in the first and second embodiments can be maintained.

  In Embodiment 3, nitrogen is used as the second gas. By generating the microbubbles 40 using nitrogen, which is a general-purpose gas harmless to the human body, the cost of generating the microbubbles 40 can be reduced while ensuring safety. Further, since nitrogen is a water-insoluble gas (non-soluble gas), the effect of maintaining the state of the fine bubbles 40 can be more effectively exerted.

  The above principle is not limited to nitrogen, and it is assumed that the same applies to any gas having a dissolution rate lower than that of the first gas which is a basic gas. When selecting the second gas, a gas having a lower (lower) dissolution rate (solubility) in water than the first gas under the same conditions including temperature and pressure may be selected. . Examples of such a second gas include nitrogen, hydrogen, carbon monoxide, butane, oxygen, methane, propane, ethane, nitrogen monoxide, ethylene, propene, acetylene, and carbon dioxide in order of solubility. . In particular, when a water-insoluble gas such as nitric oxide, oxygen, and hydrogen is used, the effect of maintaining the state of the fine bubbles 40 can be more effectively exerted.

  In the columns of “(3) Promotion of adsorption of metal ions” and “(4) Promotion of crystallization of metal ions”, it is described with reference to FIGS. 10 and 11 that nitrogen is dissolved in hard water. However, it is considered that this reaction occurred at the same time. Nitrogen is insoluble in water because it is insoluble in water, and has a strong effect of maintaining the state of the microbubbles 40. However, there is also a considerable amount of soluble nitrogen. Therefore, the phenomenon in which nitrogen is dissolved in water described in the sections of "(3) Promotion of metal ion adsorption" and "(4) Promotion of metal ion crystallization" is not small, and "(6) Second gas It is considered that the nitrogen described in the section “Maintaining fine bubbles” occurs simultaneously with the phenomenon of maintaining fine bubbles.

As described above, the microbubble generating section according to the third embodiment includes the first gas which reacts with water to provide hydroxyl ions and the second gas having a dissolution rate lower than that of the first gas. To generate fine bubbles 40 by a mixed gas obtained by mixing The first gas, which is a hydroxyl ion donor gas, reacts with water to increase the proportion of OH ^{− on} the surface of the microbubbles 40. Thereby, the effect of adsorbing metal ions such as Ca ²⁺ on the fine bubbles 40 can be increased. Further, by mixing the second gas having a dissolution rate lower than that of the first gas, the fine bubbles 40 are prevented from being completely dissolved in water, and the state of the fine bubbles 40 is maintained. Can be.

  In the third embodiment, the first gas is a soluble basic gas (ammonia). As described above, the first gas, which is a basic gas, is dissolved in water first, and the second gas having a lower dissolution rate than the basic gas is negatively charged. The effect can be obtained by utilizing the difference.

The mixing ratio of ammonia and nitrogen in the microbubbles 40 may be set to an arbitrary value. For example, the mixing ratio of nitrogen to ammonia may be set to be large (for example, the amount of ammonia: nitrogen ( Volume ratio) is 1:99). According to such a setting, the region where OH ⁻ increases due to the dissolution of ammonia remains only in the vicinity of the surface of the fine bubbles 40, and the ratio of OH ⁻ hardly changes at a position away from the fine bubbles 40. In this way, the water quality of the whole water can be kept unchanged while changing only the vicinity of the surface of the microbubbles 40. On the other hand, by increasing the proportion of nitrogen, the state of the fine bubbles 40 can be maintained for a longer time. As described above, the above-described effect is achieved by setting the amount of the second gas, which is lower in dissolution rate than the basic gas, in the mixed gas to be larger than the amount of the first gas that is the basic gas. be able to. In addition, under the conditions of the same temperature and the same pressure, the substance amount and the volume are proportional, so that the mixing ratio of the first gas and the second gas is set using either the substance amount or the volume. Is also good.

  Alternatively, the mixing ratio of ammonia to nitrogen may be set to be large. According to such a setting, metal ions contained in hard water can be more crystallized and removed. The principle of such crystallization promotion will be described in Experimental Example 3-5.

Further, in the third embodiment, unlike the supply mode in which ammonia and nitrogen are separately formed into fine bubbles and the mixed bubbles are separately supplied to hard water without being mixed, fine bubbles 40 formed by a mixed gas in which ammonia and nitrogen are mixed are used. To hard water. According to such a supply form, since ammonia is prevented from being dissolved alone at a position away from the microbubbles 40, the function of increasing OH ⁻ only near the surface of the microbubbles 40 is sufficiently exhibited. be able to.

  Next, the effect of adsorbing metal ions on the microbubbles 40 by the mixed gas obtained by mixing the first gas, ammonia, and the second gas, nitrogen, in particular, until the metal ions are finally crystallized. The hypothesis principle will be described with reference to the schematic diagram of FIG.

As shown in FIG. 14, when the microbubbles 40 are supplied into hard water, water-soluble ammonia among the ammonia and nitrogen constituting the microbubbles 40 is dissolved in the surrounding water (ammonia gas dissolution). As a result, as described in the section of “(5) Change in potential of microbubble surface due to first gas”, NH ₄ ⁺ is generated on the surface of microbubble 40 and the ratio of OH ⁻ is increased (surface concentration). ). At this time, the effect of adsorbing Ca ²⁺ ions is increasing.

As the surface concentration further proceeds, the concentration of OH ^{− on} the surface of the microbubbles 40 becomes maximum. That is, the pH on the surface of the microbubbles 40 becomes maximum, and the zeta potential of the microbubbles 40 becomes maximum (local pH is large, zeta potential is large).

In the above-described states of “dissolution of ammonia gas”, “surface concentration”, and “large local pH and large zeta potential”, Ca ²⁺ is in a state of being adsorbed by the fine bubbles 40. At this time, if the fine bubbles 40 adsorbing Ca ²⁺ are separated from the hard water, metal ions can be removed from the hard water.

When the separation is not performed or the separation is performed and the fine bubbles 40 remain, crystallization of Ca ²⁺ adsorbed on the surface of the fine bubbles 40 starts. Specifically, Ca ²⁺ is crystallized and precipitated as crystals 42. Further, with the precipitation of the crystal 42, the disappearance of the microbubbles 40 starts (disappears).

As the crystallization of Ca ²⁺ and the disappearance of the fine bubbles 40 progress, the water-insoluble nitrogen, which has maintained the state of the fine bubbles 40, diffuses into water as a dissolved gas (dissolved gas diffusion).

  In the state of “disappearance” and “dissolved gas diffusion” described above, those contained as metal ions in hard water are precipitated as crystals 42. By separating the crystals 42 thus precipitated from hard water, metal ions in hard water can be crystallized and removed.

(Experimental example 3-5)
Next, a description will be given of Experimental Example 3-5 performed to confirm the effect of the mixing ratio of ammonia and nitrogen in the microbubbles 40 on the crystallization of the metal component. Here, an experiment was performed using the device 50 shown in FIG.

  FIG. 15 is a diagram illustrating a schematic configuration of an apparatus 50 used in Experimental Example 3-5. An apparatus 50 shown in FIG. 15 includes a mixed gas supply unit 52, a processing tank 54, a first pipe 56, a second pipe 58, a water sampling valve 60, a water sampling unit 62, and a water storage tank 64. , A pump 66, a flow control valve 68, and a flow meter 70.

  The mixed gas supply unit 52 is a member that supplies a mixed gas to the processing tank 54. The mixed gas supply unit 52 includes an ammonia supply source 72, a nitrogen supply source 74, a mixing ratio adjustment valve 76, a supply pipe 78, and a fine bubble generation unit 80.

  The mixed gas supply unit 52 uses the ammonia supply source 72 and the nitrogen supply source 74 to generate a mixed gas in which ammonia (first gas) and nitrogen (second gas) are mixed. The mixing ratio of ammonia and nitrogen can be set to an arbitrary ratio by a mixing ratio adjusting valve 76. The mixed gas is supplied through a supply pipe 78 to a microbubble generator 80 provided at the bottom of the processing tank 54. The fine bubble generating section 80 is a member that converts the mixed gas into fine bubbles.

  The processing tank 54 is a tank (hard water storage unit) that stores hard water as processing water to be processed. By supplying the microbubbles of the mixed gas into the hard water of the treatment tank 54, the removal of metal components from the hard water, particularly crystallization, is performed according to the principle described in the third embodiment. The treated water after the treatment is sent to the first pipe 56. A water sampling valve 60 is provided in the middle of the first pipe 56. By opening and closing the water sampling valve 60, the processing water passing through the first pipe 56 is sampled. The sampled treated water is put into the sampler 62.

  The first pipe 56 is connected to a water storage tank 64. The water storage tank 64 is a tank for storing treated water. The treated water stored in the water storage tank 64 is returned to the treatment tank 54 through the second pipe 58. Thereby, the treated water circulates.

  A pump 66, a flow control valve 68, and a flow meter 70 are attached to the second pipe 58. The pump 66 is a member that generates a driving force for flowing the treated water in the water storage tank 64 to the second pipe 58. The flow rate adjustment valve 68 is a valve for adjusting the flow rate of the treated water passing through the second pipe 58. The flow meter 70 is a device that measures the flow rate of the treated water flowing through the second pipe 58.

  Using such an apparatus 50, while continuously operating the pump 66, the processing of removing the metal component in the hard water is performed in the processing tank 54, and the processed water after the processing is collected from the water sampling device 62 to adjust various parameters. It was measured. In Experimental Example 3-5, the rate at which the metal component contained in the treated water crystallized (crystallization rate) was investigated. The crystallization ratio in the present specification is not limited to a structure in which atoms and molecules are regularly and periodically arranged, but simply means a ratio of a substance precipitated as a solid. The crystallization rate may be referred to as “precipitation rate”.

  FIG. 16 shows an example of the result of observing the treated water actually treated in Experimental Example 3-5 with a scanning electron microscope (SEM). As shown in FIG. 16, many crystals 84 are precipitated in the treated water 82.

  In Experimental Examples 3 and 4, hard water 1 was used as treated water to be treated. Hard water 1 has an Evian (registered trademark) hardness of about 300 mg / L. In Experimental Example 5, two types of hard water 1 and hard water 2 were used. Hard water 2 has Contrex (registered trademark) hardness of about 1400 mg / L.

(Experimental example 3)
In Experimental Example 3, using the above-described apparatus 50, the pump 66 was operated to allow hard water to flow into the treatment tank 54, and the treated water after a predetermined time had elapsed was sampled by the water sampling device 62 as sample water. . In Experimental Example 3, the mixing ratio of ammonia and nitrogen in the mixed gas was changed, and the difference in the crystallization ratio at each mixing ratio was investigated. Specific experimental conditions of Experimental Example 3 are shown below. In Experimental Example 3, all of the treated water supplied to the first pipe 56 from the treatment tank 54 was discarded except for the one collected by the water sampling device 62, and was not supplied to the water storage tank 64.

(Experimental conditions)
Type of treated water: Hard water 1
Mixing ratio of ammonia in mixed gas: 0% (nitrogen only), 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100% (only ammonia)
Flow rate of treated water: 2.6 L / min Flow rate of mixed gas: 0.03 L / min Time from starting operation of pump to collection: 3 minutes Measurement items of sample water: pH, Ca hardness (mg / L), Total carbonic acid concentration (mg / L)

Regarding the measurement items of the sample water, the measurement was performed by filtering the collected sample water to remove the crystal of the metal component precipitated in the sample water. The Ca hardness is a value obtained by converting the content of Ca ²⁺ contained in the treated water per unit volume into calcium carbonate (CaCO ₃ ). A commercially available measuring instrument was used for measuring the pH, Ca hardness, and total carbonic acid concentration.

  FIGS. 17A and 17B show experimental results according to Experimental Example 3. FIG.

  In FIG. 17A, the horizontal axis represents the mixing ratio (%) of ammonia in the mixed gas, and the vertical axis represents the crystallization ratio (%) of the sample water. In FIG. 17B, the horizontal axis represents the pH of the sample water, and the vertical axis represents the crystallization ratio (%) of the sample water.

  The “crystallization rate” was calculated by (Ca hardness of sample water before operation−Ca hardness of sample water after operation) / Ca hardness of sample water before operation. The crystallization ratio calculated in this manner indicates how much metal ion has crystallized in the sample water per unit volume. A higher crystallization rate indicates that more metal ions have crystallized from the sample water.

  As shown in FIGS. 17A and 17B, the higher the mixing ratio of ammonia, the higher the crystallization ratio. In particular, when the mixing ratio of ammonia is 70% or more, the crystallization ratio is dramatically increased.

  As shown in FIGS. 17A and 17B, it can be seen that the higher the mixing ratio of ammonia, the higher the pH. However, although the pH is rising, it is a value between 8.5 and 9 at the maximum. The pH standard of clean water specified by the Ministry of Health, Labor and Welfare is in the range of 5.8 to 8.6, and it can be seen that even when the mixing ratio of ammonia is high, the value is kept close to the range. A desirable drinking range of alkaline ionized water specified by the Pharmaceutical Equipment Act is pH 9-10. Since the pH value can be kept lower than this range, it can be seen that it is suitable as drinking water.

  The reason why the increase in pH does not become excessively large even when the mixing ratio of ammonia is high is not to increase the pH of the whole treated water but to increase the local pH around the microbubbles 40 as described with reference to FIG. It is considered that the pH is mainly increased.

(Experimental example 4)
In Experimental Example 4, similarly to Experimental Example 3, while using the device 50 described above, the pump 66 was operated to allow hard water to flow into the treatment tank 54, the treated water after a predetermined time had elapsed was sampled by the water sampling device 62. Collected as water. In Experimental Example 4, only two patterns of the mixture ratio of ammonia in the mixed gas, 70% and 100%, were used. Further, unlike Experimental Example 3, sample water was collected at predetermined intervals from the operation of the pump 66, and various parameters were measured. Further, unlike the experimental example 3, all the treated water supplied from the treatment tank 54 to the first pipe 56 was returned to the water storage tank 64 except for the one collected by the water sampling device 62 to circulate the treated water. . The specific experimental conditions of Experimental Example 4 are shown below.

(Experimental conditions)
Type of treated water: Hard water 1
Mixing ratio of ammonia in mixed gas: 70%, 100% (only ammonia)
Flow rate of treated water: 2.6 L / min Flow rate of mixed gas: 0.03 L / min Measurement items of sample water: pH, Ca hardness (mg / L), total carbonic acid concentration (mg / L)

  18A, 18B, and 18C show experimental results according to Experimental Example 4. FIG.

  18A, the horizontal axis represents the operation time (minute) of the pump 66, and the vertical axis represents the crystallization ratio (%) of the sample water. 18B, the horizontal axis represents the operation time (minutes) of the pump 66, and the vertical axis represents the Ca hardness (mg / L) of the sample water. 18C, the horizontal axis represents the operation time (minutes) of the pump 66, and the vertical axis represents the pH of the sample water.

As shown in FIG. 18A, the crystallization ratio increases as the operation time elapses, regardless of whether the mixing ratio of ammonia is 70% or 100%. Also, as shown in FIG. 18B, the Ca hardness decreases as the operation time elapses. From this, it can be seen that the metal component Ca ²⁺ dissolved in the hard water was crystallized as CaCO ₃ by the introduction of the fine bubbles by the mixed gas.

On the other hand, when the mixing ratio of ammonia is 100%, the rate of increase in the crystallization rate and the rate of decrease in Ca hardness are faster when the mixing ratio of ammonia is 100%. This indicates that ammonia greatly contributes to the crystallization of Ca ²⁺ into CaCO ₃ .

  As shown in FIG. 18C, as the operation time elapses, the pH gradually increases regardless of whether the mixing ratio of ammonia is 70% or 100%. There is no significant difference in the pH value between the case where the mixing ratio of ammonia is 70% and the case where the mixing ratio of ammonia is 100%. Further, even when the operation time has passed 50 minutes, the pH is between 9 and 10, and has not risen excessively. As described above with reference to FIG. 14, the reason why the rate of increase in pH is not so fast is that, instead of increasing the pH of the entire treated water, the local pH around the microbubbles 40 is mainly increased. It is thought that there is a point.

(Experimental example 5)
In Experimental Example 5, similarly to Experimental Examples 3 and 4, while using the above-described apparatus 50 to operate the pump 66 and allow hard water to flow into the treatment tank 54, the treated water after a predetermined time has passed to the water sampling device 62. It was collected as sample water. As in Experimental Example 4, sample water was collected at predetermined intervals from the operation of the pump 66, and various parameters were measured. Similarly to Experimental Example 4, all of the treated water supplied from the treatment tank 54 to the first pipe 56 is returned to the water storage tank 64 except for the one collected by the water sampling device 62 so that the treated water is circulated. I made it. On the other hand, in Experimental Example 5, only one pattern in which the mixture ratio of ammonia in the mixed gas was 70% was used. Further, unlike the experimental examples 3 and 4, two types of hard water, hard water 1 (hardness of about 300 mg / L) and hard water 2 (hardness of about 1400 mg / L), were used as treated water. The specific experimental conditions of Experimental Example 5 are shown below.

(Experimental conditions)
Type of treated water: Hard water 1, Hard water 2
Mixing ratio of ammonia in mixed gas: 70%
Flow rate of treated water: 2.6 L / min Flow rate of mixed gas: 0.03 L / min Measurement items of sample water: pH, Ca hardness (mg / L), total coal
Acid concentration (mg / L)

  19A, 19B, 19C, and 19D show experimental results according to Experimental Example 5.

  In FIG. 19A, the horizontal axis represents the operation time (minutes) of the pump 66, and the vertical axis represents the crystallization ratio (%) of the sample water. In FIG. 19B, the horizontal axis represents the operation time (minutes) of the pump 66, and the vertical axis represents the Ca hardness (mg / L) of the sample water. 19C, the horizontal axis represents the operation time (minutes) of the pump 66, and the vertical axis represents the pH of the sample water. FIG. 19D is a graph of FIG. 19B in which the total carbonic acid concentration (mg / L) is added to the vertical axis.

As shown in FIGS. 19A and 19B, in both the hard water 1 and the hard water 2, the crystallization ratio increases as the operation time elapses, and the Ca hardness decreases. From this, it can be seen that the metal component Ca ²⁺ dissolved in the hard water was crystallized as CaCO ₃ by the introduction of the fine bubbles by the mixed gas.

  Further, as shown in FIGS. 19A and 19C, it can be seen that the hard water 1 and the hard water 2 have significantly different crystallization rates and pH increasing rates. Specifically, it can be seen that the hard water 1 has a higher crystallization rate and a higher pH rising rate than the hard water 2. In this regard, the present inventors focused on “total carbonic acid concentration” and considered based on the data shown in FIG. 19D.

As shown in FIG. 19D, the value when the operation time is 50 minutes is 150 to 200 mg / L with respect to the total carbonic acid concentration of the hard water 1. That is, the hard water 1 contains a large amount of HCO ₃ ⁻ and CO ₃ ^{2 −} . The crystallization rate of the hard water 1 when the operation time is 50 minutes has reached 70 to 80% as shown in FIG. 19A. On the other hand, the value of the total carbonic acid concentration of the hard water 2 when the operation time is 70 minutes is about 20 mg / L. Compared to the hard water 1, it can be seen that the hard water 2 has a significantly lower content of HCO ₃ ⁻ and CO ₃ ²⁻ . The crystallization rate of the hard water 2 when the operation time is 70 minutes is estimated to be about 40% according to the data shown in FIG. 19A.

HCO ₃ ^- and _CO ^{3 2-} functions as a component for crystallizing the ^{Ca 2+} as CaCO ₃ as described in the principle of embodiment 1-3. It is considered that the hard water 1 has a higher crystallization rate than the hard water 2 due to the high content of HCO ₃ ⁻ and CO ₃ ^{2 −} .

  Table 1 below shows the content of the metal components contained in the hard waters 1 and 2 and the total carbonic acid concentration.

As shown in Table 1, the contents of Ca, Mg, and CO ₃ ^2- per unit volume contained in Evian (registered trademark), which is hard water 1, are 80, 26, and 357 mg / L, respectively. The contents of Ca, Mg, and CO ₃ ^2- per unit volume contained in Contrex (registered trademark), which is hard water 2, are 468, 74.8, and 372 mg / L. As described above, the content of CO ₃ ^2- per unit volume contained in the hard water 1 and the hard water 2 is almost the same at 357 mg / L and 372 mg / L. On the other hand, the amount of CO ₃ ²⁻ necessary for dissolving Ca and Mg with respect to the content of Ca and Mg contained in hard water is about 184 mg / L for hard water 1 and about 887 mg / L for hard water 2. . That is, in the hard water 1 for _CO ^{3 2-} in an amount required to dissolve the Ca and Mg, the actual _CO ³ amount of ² contained in is left over about 173 mg / L. This is because, when charged with the mixed gas by the fine bubbles, means that the CO ₃ ^2- are abundant for crystallizing Ca ^2+. In contrast, in hard water 2, with respect to _CO ^{3 2-} in an amount required to dissolve the Ca and Mg, in fact _CO ³ amount of ² that contains the missing about 515 mg / L. This is thought to be because when a mixed gas containing fine bubbles is introduced, the amount of CO ₃ ²⁻ for crystallizing Ca ²⁺ is small, and crystallization is not promoted.

Than the results, HCO ₃ in hard water to be treated ^- if it contains and the rich carbonate CO ₃ ^2-, etc., is considered to be improved to increase the rate of crystallization. In order to increase the total carbonic acid amount of the hard water based on this, carbon dioxide gas may be injected into the hard water before the fine bubbles are injected. Specifically, the apparatus may further include a carbon dioxide gas generator that generates carbon dioxide gas. Then, before supplying the microbubbles generated by the microbubble generating unit to the hard water, the carbon dioxide gas may be generated by the carbon dioxide generating unit and supplied to the hard water. Thereby, it is considered that crystallization of the metal component in the hard water can be promoted.

  As described above, according to Experimental Example 3-5, crystallization of the metal component can be promoted by setting the amount of ammonia to be larger than the amount of nitrogen in the mixed gas. Further, by setting the mixing ratio of ammonia in the mixed gas to 70% or more, crystallization of the metal component can be greatly promoted.

(Experimental example 6)
Experimental example 6 is a sensory evaluation experiment for evaluating “foaming” with respect to the sample water (soft water) treated using the device 50 described above. Foaming is related to the foaming power due to the height and size of foam generated from the water surface. Generally, it is considered that the smaller the hardness component is, the larger the foaming becomes. For example, there is an advantage that the cleaning effect is high when used in a cleaning application.

  In Experimental Example 6, unlike Experimental Example 3-5, fine bubbles were generated based on ammonia as a single gas instead of a mixed gas. That is, in the apparatus 50 shown in FIG. 15, fine bubbles were generated using only the ammonia supply source 72 without using the nitrogen supply source 74. The method of using the device 50 is the same as that of the experimental example 3-5, and thus the description is omitted.

  The experimental method of Experimental Example 6 is based on the standard for foaming of the Society of Air Conditioning and Sanitary Engineers: SHASE-S218. Specifically, diluting water prepared by diluting 1.5 g of pure soap with 200 ml of water was prepared, and 1 mL of the diluting water and 9 mL of the target treated water were mixed and put into a measuring cylinder as 10 mL of evaluation water. The pure soap used was a cosmetic soap cow brand red box a1 (Milk Soap Co., Ltd.), and the 200 ml of water used was distilled water from Auto Still, WG221 (Yamato Kagaku Co., Ltd.). After the measuring cylinder was shaken 50 times, the height of the foam rising from the water surface one minute later was measured.

  In Experimental Example 6, the same experiment was performed using three types of hard water, tap water, and pure water in addition to the sample water treated by the device 50. The hardness of the water and the sample water is as follows.

Hard water hardness: Total hardness 300 mg / L, Ca hardness 200 mg / L, Mg hardness 100 mg / L
Tap water hardness: Total hardness 72 mg / L, Ca hardness 49 mg / L, Mg hardness 23 mg / L
Pure water hardness: Total hardness 0 mg / L, Ca hardness 0 mg / L, Mg hardness 0 mg / L
Sample water hardness: Total hardness 118 mg / L, Ca hardness 21 mg / L, Mg hardness 97 mg / L

  FIG. 20 shows an experimental result according to Experimental Example 6. In FIG. 20, the horizontal axis represents the type of water, and the vertical axis represents the height (mm) of bubbles extending from the water surface of the evaluation water. The vertical axis represents foaming / foaming power.

  As shown in FIG. 20, "hard water", which has the highest Ca hardness and Mg hardness, has almost no bubbling and is close to 0, whereas "tap water", "sample water" and "pure water" are about the same. High foaming. That is, the “sample water” treated using the device 50 has improved foaming with respect to the hard water before the treatment, and realizes foaming similar to “tap water” and “pure water”. This indicates that foaming can be improved by removing metal ions from hard water according to the method of the embodiment, and foaming at the same level as that of tap water or pure water that is soft water can be realized.

  Comparing the results shown in FIG. 20 with the specific values of the hardness, the lower the Ca hardness, the greater the foaming. This shows that the value of Ca hardness is a dominant parameter that directly affects foaming rather than Mg hardness.

(Experimental example 7)
In Experimental Example 7, treated water (hard water) was treated using the same device 50 (FIG. 15) as in Experimental Example 3-5, and the crystallization ratio of the treated sample water was compared.

  In Experimental Example 7, the difference in crystallization ratio between the case where microbubbles which are fine bubbles were used and the case where millibubbles which were not fine bubbles were used were compared. That is, in the device 50 shown in FIG. 15, microbubbles are generated using the microbubble generator 80 as it is, and another bubble generator (not shown) is used instead of the microbubble generator 80. The experiment was performed with two patterns in which millimeter bubbles were generated.

  Further, in Experimental Example 7, unlike Experimental Example 3-5, bubbles were generated based on ozone which was a single gas instead of a mixed gas. That is, in the apparatus 50 shown in FIG. 15, an ozone supply source (not shown) was used instead of the ammonia supply source 72 and the nitrogen supply source 74. As described in Embodiment 3, ozone gas is a hydroxyl ion donating gas.

  The experimental conditions of Experimental Example 7 are as follows.

Type of treated water (common): Hard water 1
Treated water flow rate (common): 12 L / min
Amount of water stored in processing tank 54 (common): 9L
Ozone gas flow rate (common): 0.12 L / min
Average bubble diameter of microbubbles: 56 μm
Average bubble diameter of millibubbles: 1021 μm
Measurement items of sample water (common): Ca hardness (mg / L), total hardness (mg / L)

  Experimental results according to Experimental Example 7 are shown in FIGS. 21A and 21B.

  In FIG. 21A, the horizontal axis represents time (minutes), and the vertical axis represents the crystallization ratio (%) of Ca hardness. In FIG. 21B, the horizontal axis represents time (minutes), and the vertical axis represents the crystallization ratio (%) of the total hardness.

  As shown in FIGS. 21A and 21B, it can be seen that the microbubbles achieve a higher crystallization rate than the millibubbles with respect to both the Ca hardness and the total hardness. In other words, the crystallization rate is higher when microbubbles, which are microbubbles, are used than when microbubbles, which are not microbubbles, are used, demonstrating the effect of crystallization of metal ions by the microbubbles.

  The present invention is not limited to the above-described embodiment, but can be implemented in other various modes. For example, in the above description, air or nitrogen was used as the ion removing gas in the water softening treatment, but the present invention is not limited to this. A gas other than air and nitrogen may be used as the ion removing gas.

In the above description, carbon dioxide is used as a dissolving gas for performing the regeneration treatment, but the present invention is not limited to this. For example, as the dissolution gas, hydrogen sulfide is a gas emitted hydrogen ions when dissolved in water ^{_{(H 2 S → H + +}} HS -) and hydrogen chloride ^{(HCL → H + + CL -} ) may be used.

  In the above description, a dissolving gas is used as an example of the dissolving agent for performing the regeneration treatment, but the present invention is not limited to this. For example, a liquid (solution for dissolving) that dissolves the crystal of the metal component may be used as the solubilizer. Examples of such a liquid include hydrochloric acid, sulfuric acid, citric acid, and ascorbic acid. By using such a liquid, the size of the dissolving agent supply unit 8 can be reduced. Further, the frequency of changing the dissolving agent can be reduced. Further, when a liquid is used as the dissolving agent, gas can be suppressed from entering the pump P, so that the necessity of disposing the dissolving agent supply unit 8 on the downstream side of the pump P in the hard water flow direction can be eliminated. it can. That is, the dissolving agent supply unit 8 may be disposed in a circulation flow path including the primary flow path 2, the ion removing device 3, the separation device 4, and the return flow channel 12. Also according to this configuration, a regenerating process can be performed by supplying a dissolving agent to the separation device 4 to dissolve crystals attached to the separation device 4.

  In the above description, the separation device 4 is a cyclone type centrifugal separation device, but the present invention is not limited to this. For example, the separation device 4 may be a water purification filter such as a hollow fiber membrane.

  In the above description, only the fine bubbles containing the ion removing gas are supplied into the hard water, but the present invention is not limited to this. For example, another gas may be supplied in addition to the microbubbles containing the ion removing gas in hard water. In this case, another gas may be supplied to hard water as fine bubbles, or may be supplied to hard water as ordinary bubbles.

  In the above description, the opening and closing operations of the first valve 15A, the second valve 15B, and the third valve 15C are automatically controlled by the control unit 6, but the present invention is not limited to this. The opening and closing operations of the first valve 15A, the second valve 15B, and the third valve 15C may be manually performed.

  In the above description, a case is described in which fine bubbles are used in which two types of gases, a first gas which is a basic gas and a second gas having a dissolution rate lower than that of the first gas, are mixed. Alternatively, another gas may be mixed in addition to these two types of gases. That is, fine bubbles of a mixed gas obtained by mixing two or more types of gases including the first gas and the second gas may be used.

  Note that by appropriately combining any of the above-described various embodiments and modified examples, the effects of the respective embodiments can be achieved.

  While this disclosure has been fully described in connection with preferred embodiments thereof with reference to the accompanying drawings, various variations and modifications will be apparent to those skilled in the art. It is to be understood that such changes and modifications are included therein unless they depart from the scope of the present disclosure as set forth in the appended claims. In addition, combinations of elements and changes in the order in each embodiment can be realized without departing from the scope and spirit of the present disclosure.

  INDUSTRIAL APPLICABILITY The ion removal system according to the present invention is excellent in maintainability and environmental friendliness, and therefore is useful for both home-use ion removal systems and business-use ion removal systems.

DESCRIPTION OF SYMBOLS 1 Ion removal system 2 Primary side flow path 3 Ion removal device 3A Hard water storage part 3B Fine bubble generation part 3C Connection flow path 4 Separation device 4A Separation part 4Aa Inner peripheral surface 4B Crystal storage part 4Ba Discharge flow path 5 Secondary flow path Reference Signs List 6 Control part 7 Ion removal gas supply part 8 Solvent supply part 9 Gas switching mechanism 10 Open / close valve 11 Drain side backflow prevention mechanism 12 Return path 13 Supply side backflow prevention mechanism 14 Bypass flow path 15A First valve 15B Second valve 15C Third valve 16 Deaerator 20 Device 21 Hard water 22 Water tank 22a Bottom surface 22b Water surface 24 Gas supply unit 25 First pipe 26 Microbubble generator 27 Second pipe 28 Pump 30 First water intake unit 32 Second water intake unit 34 Metal ion Concentration detector 40 Microbubbles 42 Crystal D1 Distance from first water intake section to second water intake section 50 Device 52 Mixed gas supply section 54 Processing tank 56 First pipe 5 Second piping 60 Water sampling valve 62 Water sampling device 64 Water storage tank 66 Pump 68 Flow rate adjustment valve 70 Flow meter 72 Ammonia supply source 74 Nitrogen supply source 76 Mixing ratio adjustment valve 78 Supply pipe 80 Microbubble generator 82 Treated water 84 Crystal 90 Device 91 Water tank 92 First pipe 93 Pump 94 Second pipe 95 Mist nozzle 96 Hard water 97 Sample 98 Open / close valve

Claims (4)

A degassing device for degassing carbon dioxide contained in hard water,
A hard water storage unit that stores hard water in which carbon dioxide has been degassed by the deaerator, and a fine bubble generation unit that generates fine bubbles and supplies the hard water to the hard water storage unit. An ion removal device that removes metal ions from hard water by adsorbing metal ions to the microbubbles,
An ion removal system comprising:   The ion removal system according to claim 1, wherein the degassing device degass carbon dioxide contained in the hard water by spraying hard water in a mist.   The ion removal system according to claim 1, wherein the degassing device degass carbon dioxide contained in the hard water by supplying gas to the hard water and bubbling the gas.   4. The ion removal system according to claim 3, wherein bubbles generated in the hard water by the bubbling have a larger average outer diameter than fine bubbles generated by the fine bubble generating unit. 5.

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