WO2020158565A1

WO2020158565A1 - Water softening apparatus and water softening method

Info

Publication number: WO2020158565A1
Application number: PCT/JP2020/002301
Authority: WO
Inventors: 義弘坂口; 綾音竹久
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2019-01-31
Filing date: 2020-01-23
Publication date: 2020-08-06

Abstract

A water softening apparatus equipped with a treatment tank in which water of interest, which is water to be softened, is introduced, a pH adjustment section for adjusting the pH value of the water of interest, a seed crystal feeding section for feeding a seed crystal of a hardness component to the water of interest, and an ultrasonic wave irradiation section for irradiating the water of interest with ultrasonic waves; and a water softening method comprising step A of adjusting the pH value of water of interest which is water to be softened and step B of feeding a seed crystal of a hardness component to the water of interest which is water to be softened, wherein the step A and step B are carried out in a random order and step C of irradiating the water of interest with ultrasonic waves is further included subsequent to the completion of both of step A and step B.

Description

Water softening device and water softening method

The present invention relates to a water softening device and a water softening method.

Various methods have been proposed as a water softening method in a water softening device for softening hard water. Among them, a water softening device using an ion exchange resin is a structure for exchanging calcium ions and magnesium ions contained in tap water etc. for sodium ions to soften water, and has been widely used because of its simple structure. (See Patent Document 1). In such a water softening device, when the water softening treatment is continued, the ion exchange capacity of the ion exchange resin gradually decreases. However, even if the ion exchange capacity is reduced, the ion exchange resin can be recovered by the regeneration treatment. Therefore, the water softening device using the ion exchange resin can be continuously used by regenerating the ion exchange resin.

Other known methods for softening water include electrolysis (see Patent Document 2) and an ion exchange membrane (see Patent Document 3).

Japanese Patent Laid-Open No. 2014-100633 Japanese Patent Laid-Open No. 5-285481 JP, 2003-053339, A

However, in a water softening device using an ion exchange resin, a large amount of salt is used during the regeneration treatment of the ion exchange resin, which causes an environmental problem, and an alternative technique is required. In addition, there is a limit to the recovery of the ion exchange resin by the regenerating process, and the recovery becomes difficult if the ion exchange resin is used for a predetermined period or longer. That is, the ion exchange resin has a life and cannot be used beyond the life period. In addition, electrolysis requires maintenance such as removal of electrode deposits. Further, in the case of using the ion exchange membrane, the water to be treated needs to have a high pressure so that the water to be treated can pass through the ion exchange membrane.

As described above, in the configuration of the conventional water softening device, it is difficult to achieve water softening with a simple configuration, because complicated maintenance such as regeneration processing is required, a mechanism for increasing the water pressure is required. Met.

The present invention has been made in view of such problems of the conventional technology. An object of the present invention is to provide a water softening device and a water softening method that can realize softening of hard water with a simple configuration.

The water softening device according to the first aspect of the present invention is a treatment tank into which water to be treated, which is a target of water softening, is input, a pH adjusting unit for adjusting the pH of the water to be treated, and a hardness component in the water to be treated. A seed crystal supply unit for supplying the seed crystal of No. 2 and an ultrasonic wave irradiation unit for irradiating the water to be treated with ultrasonic waves.

The water softening method according to the second aspect of the present invention comprises step A of adjusting the pH of the water to be treated to be softened, and supplying the seed crystal of the hardness component to the water to be treated to be water softened. And step B which is performed in no particular order, and after performing both step A and step B, step C of irradiating the water to be treated with ultrasonic waves is included.

FIG. 1 is a conceptual diagram showing an example of a water softening device according to this embodiment. FIG. 2 is a conceptual diagram showing an example of the water softening device according to the present embodiment. FIG. 3 is a graph showing the reduction rate of calcium ions with respect to the treatment time in Example 1 and Comparative Example 1. FIG. 4 is a graph showing changes in pH with respect to treatment time in Example 2. FIG. 5 is a graph showing the removal rate of calcium ions with respect to the treatment time in Example 2. FIG. 6 is a graph showing changes in pH with respect to treatment time in Example 3. FIG. 7 is a graph showing the removal rate of calcium ions with respect to the treatment time in Example 3. FIG. 8 is a graph showing changes in pH with respect to treatment time in Examples 4 and 5. FIG. 9 is a graph showing the removal rate of calcium ions with respect to the treatment time in Examples 4 and 5. FIG. 10 is a graph showing changes in pH with respect to the concentration of calcium carbonate in Examples 6-1 to 9-4. FIG. 11 is a graph showing the calcium ion removal rate with respect to the concentration of calcium carbonate in Examples 6-1 to 9-4.

<Water softener>
The water softening device of the present embodiment is a treatment tank into which water to be treated which is a target of water softening is introduced, a pH adjusting unit for adjusting the pH of the water to be treated, and a seed crystal of a hardness component to the water to be treated. The present invention is characterized in that it has a seed crystal supply unit for irradiating the water to be treated and an ultrasonic wave irradiation unit for irradiating the water to be treated with ultrasonic waves.

In the water softener of the present embodiment, the pH of the water to be treated that has been put into the treatment tank is adjusted by the pH adjusting unit. Specifically, as described below, the pH of the water to be treated is adjusted to 7.8 or higher. Further, the seed crystal supply unit supplies the hardness component seed crystal (carbonate) into the water to be treated. Then, the ultrasonic wave is radiated by the ultrasonic wave irradiating unit to the water to be treated to which the pH is adjusted and the seed crystal is supplied. Then, with the seed crystal as a nucleus, a carbonate is crystallized from the carbonate ion in the water to be treated and the cation of the hardness component. At this time, the ultrasonic irradiation increases the ion concentration in the ultrasonic wave in the dense portion of the ultrasonic wave in the water to be treated, and promotes the crystallization of the carbonate with the seed crystal as the nucleus. From the above, in the water to be treated, the hardness component ions are reduced by crystallization, and the water is softened.

FIG. 1 is a conceptual diagram showing an example of the water softening device of this embodiment. The water softening device 10 shown in FIG. 1 includes a treatment tank 12, a pH adjusting unit 16, a seed crystal supplying unit 18, and an ultrasonic wave irradiating unit 20. The treatment tank 12 is filled with the water 14 to be treated which is to be softened. The pH adjusting unit 16 adjusts the pH of the water to be treated 14 to a desired value, and the seed crystal supplying unit 18 supplies the seed crystal of the hardness component to the water to be treated 14. The ultrasonic wave irradiator 20 irradiates the water to be treated with ultrasonic waves through the vibrator 22. The water softening device 10 further includes a pH detector 24 that detects the pH of the water 14 to be treated, and a chiller 27 that cools the water 14 to be treated.

The treatment tank 12 may have any shape as long as it can contain the water 14 to be treated and has an opening for injecting the water 14 to be treated. The material of the processing tank 12 can be appropriately selected from those used in known water softening devices.

The pH adjuster 16 adjusts the pH of the water 14 to be treated. Here, the water to be treated 14 permanently contains a carbonic acid component originating from carbon dioxide in the atmosphere, and the carbonic acid component in the water to be treated 14 is a carbonate ion (CO ₃ ²⁻ ) or a hydrogen carbonate ion (HCO). ₃ ^-) exists as. The carbonate ion and the hydrogen carbonate ion exist in the water 14 to be treated in an equilibrium state in which the abundance ratio changes depending on the pH. The higher the pH, the higher the carbonate ion abundance ratio. In the present embodiment, the pH adjuster 16 adjusts the pH of the water 14 to be treated to a high value to increase the carbonate ion abundance ratio and grow carbonate crystals.

The means for adjusting the pH by the pH adjusting unit 16 is not particularly limited. For example, a means for supplying an alkali agent such as sodium hydroxide or potassium hydroxide, or a buffer agent such as Tris buffer, NH ₃ —NH ₄ Cl-based buffer solution having a pH of 10 or the like, or adjusting the pH by electrolysis. Means may be used.

The pH of the water to be treated 14 adjusted by the pH adjusting unit 16 is preferably 7.8 or higher, and more preferably 9.0 or higher. As described above, the higher the pH of the water to be treated 14 is, the higher the carbonate ion abundance ratio is, and the more easily the crystallization proceeds. That is, in order to promote crystallization, the pH of the water to be treated 14 is preferably 7.8 or higher, more preferably 9.0 or higher. In addition, in this specification, pH is a value in 25 degreeC.

On the other hand, if an alkaline agent is used to adjust the pH, the pH will drop as it is consumed. Therefore, when the pH is lowered, the ratio of carbonate ions does not increase unless the alkali agent is replenished, and crystallization tends not to proceed sufficiently. However, when a buffering agent is added, fluctuations in pH can be suppressed, the ratio of carbonate ions is stabilized, and stable crystallization can be performed. From the viewpoint of promoting crystallization, it is preferable that the buffering agent exhibits a buffering ability at a pH of 7.8 or higher.

The seed crystal supply unit 18 supplies a seed crystal of hardness component. In the present embodiment, the hardness component refers to calcium and magnesium, and the seed crystal used is one that grows a crystal of a calcium salt or a magnesium salt with itself as a nucleus. Specific examples of the seed crystal include calcium carbonate as the seed crystal for the calcium component. Examples of the seed crystal for the magnesium component include magnesium carbonate.

The seed crystal supply unit 18 may mechanically supply the seed crystal by a driving means such as a motor, or by opening or closing a container containing the seed crystal mechanically or artificially. A means for supplying seed crystals from the container may be used.

The average grain size of the seed crystals supplied by the seed crystal supply unit 18 is preferably less than 2 μm. If the seed crystal has an average particle size of less than 2 μm, crystallization can be promoted regardless of its concentration. The average grain size of the seed crystal is more preferably 1 μm or less, further preferably 0.15 μm or less. The lower limit of the average particle size of the seed crystal is usually 0.1 μm.
On the other hand, the grain size of the seed crystal supplied by the seed crystal supply unit may be 2 μm or more. However, in the case of a seed crystal having an average particle size of 2 μm or more, the degree of progress of crystallization depends on the concentration. Therefore, in the case of a seed crystal having an average particle size of 2 μm or more, it is preferable to increase the concentration of the seed crystal. The specific range of the concentration will be described later.
In the present specification, the “average particle size” is a volume-based average particle size measured by a laser diffraction/scattering method, and more specifically, obtained by a particle size distribution measurement by a laser diffraction/scattering method. It is the median diameter obtained based on the particle size distribution.

A vibrator 22 is connected to the ultrasonic wave irradiation unit 20, and ultrasonic waves are emitted via the vibrator 22. The frequency of the ultrasonic waves to be applied is not particularly limited, but may be 20 kHz or higher and is preferably 1 MHz or higher. The output of ultrasonic waves is not particularly limited and can be set within a generally used range.

The water softening device 10 further includes a pH detection unit 24 that detects the pH of the water to be treated. A pH sensor 26 is connected to the pH detection unit 24, the pH of the water to be treated is measured by the pH sensor 26, and the pH detection unit 24 detects the value. As the pH detector 24 and the pH sensor 26, known ones can be applied. In addition, in this embodiment, the pH detection unit is not always necessary.

In the present embodiment, it is preferable that the water softening device 10 further has a temperature adjusting mechanism (not shown) that adjusts the temperature of the water to be treated. That is, crystallization is more likely to proceed as the temperature increases, so it is preferable to set the temperature higher by the temperature adjusting mechanism. The temperature adjusting mechanism is not particularly limited as long as it can adjust the temperature of the water to be treated.

Further, the water softening device 10 has a chiller 27 for cooling the water 14 to be treated. Since the water to be treated 14 generates heat by irradiation with ultrasonic waves, it is preferable to circulate and cool the chiller 27.

The above-described water softening device 10 shown in FIG. 1 has a mode in which the water 14 to be treated stays in the treatment tank 12. In the present embodiment, the water to be treated as running water may flow into the treatment tank to be softened, and then discharged. FIG. 2 is a conceptual diagram showing a water softening device in the case where the water to be treated to be water softened is running water. The water softening device 11 shown in FIG. 2 includes a treatment tank 13, a pH adjusting unit 16, a seed crystal supplying unit 18, and an ultrasonic wave irradiating unit 20. The treatment tank 13 is provided with a flow passage 28 for allowing the treated water 14 as running water to flow into the treatment tank 13, and a passage 30 for discharging the treated water 14 that has been treated. It flows into the processing tank 13 via the and is discharged via the flow path 30. In addition, the pH adjusting unit 16, the seed crystal supplying unit 18, the ultrasonic wave irradiating unit 20, and the pH detecting unit 24 are the same as those in the water softening device 10 shown in FIG. Is omitted. Below, the treatment tank 13 which is a difference from the water softening device 10 and the water to be treated which is running water will be explained.

The processing tank 13 does not have an opening like the processing tank 12 shown in FIG. 1, and does not communicate with the outside except for the

channels

28 and 30. On the upstream side of the flow path 28, for example, a tap water supply pipe is connected, and in that case, tap water is the water to be treated. Then, similarly to the water softening device 10 shown in FIG. 1, the pH of the water to be treated 14 flowing into the treatment tank 13 is adjusted by the pH adjusting unit 16, and the seed crystal supplying unit 18 supplies the seed crystal. Then, the water to be treated 14 is irradiated with ultrasonic waves by the ultrasonic wave irradiation unit 20, and the hardness component is crystallized to be softened.

If the water to be treated is running water, the temperature rise due to ultrasonic irradiation is limited, so there is no need to install a chiller. Moreover, since it is running water, it is necessary to continuously adjust the pH. For example, the pH detection unit 24 (pH sensor 26) can be set to detect the pH value and adjust the pH when the pH value is below a certain value. Further, it can be set so as to adjust the pH according to the flow rate.

In both of the above FIG. 1 and FIG. 2, it is preferable to remove the seed crystal after water softening. The means for removing the seed crystal is not particularly limited, and known means can be applied.
For example, means for passing the water to be treated through a filter through which the seed crystal does not pass can be used.

<Softening method>
The water softening method of the present embodiment includes a step A of adjusting the pH of the water to be treated which is the object of water softening, and a step B of supplying a seed crystal of a hardness component to the water to be treated which is the object of water softening, In any order. The method is characterized by including step C of irradiating the water to be treated with ultrasonic waves after performing both step A and step B.

In the water softening method of the present embodiment, first, the pH of the water to be treated to be water softened is adjusted (step A), and a seed crystal of hardness component is supplied (step B). That is, as described above, the pH of the water to be treated is adjusted to 7.8 or higher. Further, a seed crystal (carbonate) of the hardness component is supplied to the water to be treated. Next, ultrasonic waves are radiated to the water to be treated to which the pH has been adjusted and the seed crystals have been supplied (step C). Then, as described above, in the water to be treated, the ion concentration increases in the dense part of the ultrasonic waves, and the carbonate crystallizes with the seed crystal as the nucleus. That is, the ions of the hardness component are reduced in the water to be treated, and the water is softened. Finally, the crystallized seed crystals are removed.

The water softening method of the present embodiment can be executed by, for example, the water softening device of the present embodiment described above, but is not limited to the water softening device. At least, as the instruments, there is a treatment tank containing the water to be treated, and a device for irradiating the water to be treated in the treatment tank with ultrasonic waves. The water softening method of the embodiment can be executed.
Each step will be described below.

[Step A]
In step A, the pH of the water to be treated which is to be softened is adjusted. As described above, the pH is adjusted so that the ratio of carbonate ions in the water to be treated becomes large. The higher the pH, the higher the ratio of carbonate ions, and therefore the pH of the water to be treated is preferably adjusted to 7.8 or higher, more preferably 9.0 or higher in order to further promote crystallization. ..

On the other hand, as mentioned above, if an alkaline agent is used to adjust the pH, the pH will decrease with its consumption. Therefore, when the pH is lowered, the ratio of carbonate ions does not increase unless the alkali agent is replenished, and crystallization tends not to proceed sufficiently. Therefore, it is preferable to replenish the alkaline agent every predetermined time to adjust the pH. Alternatively, the pH can be detected and an alkaline agent can be supplied to adjust the pH when the pH falls below a certain level.

Also, in step A, it is preferable to supply a buffer to the water to be treated. By supplying a buffering agent to the water to be treated, it is possible to mitigate fluctuations in the pH of the water to be treated. That is, it is possible to suppress the decrease in pH when the alkaline agent is used as described above. Specific examples of the buffering agent have been described above, and thus will be omitted here.

[Step B]
In step B, a seed crystal of hardness component (calcium component or magnesium component) is supplied to the water to be treated which is to be softened. Examples of seed crystals for the calcium component include calcium carbonate. Examples of the seed crystal for the magnesium component include magnesium carbonate.

In step B, it is preferable to supply a seed crystal having an average particle size of less than 2 μm. When a seed crystal having an average particle size of less than 2 μm is supplied, sufficient crystallization can be achieved without depending on its concentration. Further, in step B, when a seed crystal having an average particle size of less than 2 μm is supplied, the concentration of the seed crystal in the water to be treated is preferably 100 ppm or more and less than 500 ppm, more preferably 300 ppm or more and less than 500 ppm.
Further, in step B, it is preferable to supply a seed crystal having an average particle size of 2 μm or more. However, when a seed crystal having an average particle size of 2 μm or more is supplied, sufficient crystallization may not be achieved at a low concentration. In that case, in step B, the concentration of the seed crystal in the water to be treated is preferably 500 ppm or more, more preferably 1000 ppm or more.

Note that Step A and Step B are in random order, and it does not matter which of Step A and Step B is executed first.

[Step C]
In step C, the water to be treated is irradiated with ultrasonic waves after execution of both step A and step B. The ultrasonic wave to be applied may have a frequency of 20 kHz or higher, preferably 1 MHz or higher. Further, the irradiation time of ultrasonic waves can be set according to the hardness of the water to be treated. That is, when the hardness of the water to be treated is high, the irradiation time can be extended, and when the hardness is low, the irradiation time can be shortened. Further, in the case of running water, it can be appropriately set according to the flow velocity.

In step C, the temperature of the water to be treated can be adjusted to less than 30°C. That is, the water to be treated can be kept at room temperature or lower. If the temperature is lower than room temperature, crystallization usually does not proceed, or the progress speed tends to be slow even if it progresses. Crystallization is promoted also below. The lower limit of the temperature of the water to be treated is 0°C.
In step C, the temperature of the water to be treated can be adjusted to 30°C or higher. If the temperature of the water to be treated is high, crystallization is likely to proceed. Therefore, it is preferable to set the temperature to 30° C. or higher by heating or the like.

・Continuing Step C will reduce the consumption of alkaline agents and the pH of the water to be treated. Therefore, when the pH of the water to be treated decreases (for example, less than 7.8), it is preferable to add an alkaline agent.

By performing steps A to C above, softening of hard water can be achieved. However, it is preferable to remove the seed crystals because they remain after the water softening. The method for removing the seed crystal is not particularly limited, and a known method can be applied. For example, a method of passing treated water through a filter through which seed crystals do not pass can be used.

The water softening device and the water softening method of this embodiment described above can be applied to a place-of-use installed water purifier (POU) and a building entrance installed water purifier (POE).

Hereinafter, the present embodiment will be described in more detail by way of examples, but the present embodiment is not limited to these.

[Example 1]
A 200 ml beaker was filled with Evian (manufactured by Danone Japan Co., Ltd., water temperature: 20° C.) as water to be treated, and sodium hydroxide was added to adjust the pH to 7.8. Next, calcium carbonate (average particle size: 0.15 μm) was added as a seed crystal so that the concentration was 1 ppm. After that, ultrasonic waves were applied under the following conditions to soften the water. A chiller was connected to the beaker, and circulation cooling was performed to maintain the temperature of 20°C.
(Ultrasonic conditions)
Ultrasonic device: SONIFIER450 (made by Rika Ikeda)
Output: 20W
Frequency: 25kHz
Duty cycle: 50

After a lapse of a predetermined time, the amount of calcium ions was measured by chelate titration, and the reduction rate from the initial value was defined as the calcium ion reduction rate. A graph showing the reduction rate of calcium ions with respect to the treatment time is shown in FIG.

[Comparative Example 1]
Water softening was performed in the same manner as in Example 1 except that the pH was not adjusted, and the calcium ion reduction rate was calculated in the same manner as in Example 1. A graph showing the calculation result is shown in FIG.

From FIG. 3, it can be seen that the gradient of the decrease rate of calcium ions with time is steeper in Example 1 with pH adjustment than in Comparative Example 1 without pH adjustment. That is, it was shown that the pH was adjusted to sufficiently soften the water.

[Example 2]
In Example 1, the initial pH was set to 8.1, and then the same treatment was performed for 60 minutes. A graph showing the change in pH with the treatment time is shown in FIG. Further, a graph showing the removal rate of calcium ions with respect to the treatment time is shown in FIG.

[Example 3]
In Example 2, water was softened for 1 hour while replenishing sodium hydroxide every 5 minutes to adjust the pH. The change in pH with time is shown in the graph of FIG. The graph of FIG. 7 shows the removal rate of calcium ions with respect to the treatment time.

From FIGS. 4 to 5, it can be seen that the pH decreases with time and the removal rate of calcium ions decreases accordingly. Further, it can be seen from FIGS. 6 to 7 that when the alkaline agent is replenished at predetermined intervals, the decrease in pH is suppressed and the removal rate of calcium ions is improved.

[Example 4]
A 200 ml beaker was filled with Evian (manufactured by Danone Japan Co., Ltd., water temperature: 20° C.) as water to be treated, and sodium hydroxide was added to adjust the pH to 8.1. Next, calcium carbonate (average particle diameter: 0.15 μm) was added as a seed crystal so that the concentration was 100 ppm. After that, ultrasonic waves were applied under the following conditions to soften the water. A chiller was connected to the beaker, and circulation cooling was performed to maintain the temperature of 20°C.
(Ultrasonic conditions)
Ultrasonic device: Ultrasonic atomization unit (IM1-24/LW, manufactured by Seikou Giken Co., Ltd.)
Output: 17W
Frequency: 1600kHz
Duty cycle: 100

[Example 5]
Water softening was performed in the same manner as in Example 4 except that Tris buffer (0.1 M) was used instead of sodium hydroxide and the initial pH was adjusted to about 9.

FIG. 8 shows a graph showing changes in pH with respect to treatment time in Examples 4 and 5. Further, FIG. 9 shows a graph showing the removal rate of calcium ions with respect to the treatment time.

From FIG. 8, it can be seen that in Example 5 using the Tris buffer, the change in pH with time is small after adding the Tris buffer, even though nothing is done. From FIG. 9, it can be seen that the removal rate of calcium ions with respect to the treatment time is stable in the range of 70 to 75% after 5 minutes.

[Example 6-1]
A 200 ml beaker was filled with Evian (manufactured by Danone Japan Co., Ltd., water temperature: 20° C.) as water to be treated, and a Tris buffer (0.1 M) was added. Next, calcium carbonate was added as a seed crystal (average particle size: 0.15 μm) so that the concentration would be 10 ppm. After that, ultrasonic waves were applied under the following conditions to soften the water.
(Ultrasonic conditions)
Ultrasonic device: Ultrasonic atomization unit (IM1-24/LW, manufactured by Seikou Giken Co., Ltd.)
Output: 17W
Frequency: 1600kHz
Duty cycle: 100
Ultrasonic irradiation time: 1 minute

[Example 6-2]
Water softening was performed in the same manner as in Example 6-1, except that calcium carbonate was added so as to have a concentration of 100 ppm.

[Example 6-3]
Water softening was performed in the same manner as in Example 6-1, except that calcium carbonate was added so as to have a concentration of 500 ppm.

[Example 6-4]
Water softening was performed in the same manner as in Example 6-1 except that calcium carbonate was added so as to have a concentration of 1000 ppm.

[Example 7-1]
Water softening was performed in the same manner as in Example 6-1 except that calcium carbonate having an average particle size of 1.2 μm was used as a seed crystal.

[Example 7-2]
Water softening was performed in the same manner as in Example 7-1, except that calcium carbonate was added so as to have a concentration of 100 ppm.

[Example 7-3]
Water softening was performed in the same manner as in Example 7-1 except that calcium carbonate was added so that the concentration would be 500 ppm.

[Example 7-4]
Water softening was performed in the same manner as in Example 7-1 except that calcium carbonate was added so that the concentration became 1000 ppm.

[Example 8-1]
Water softening was performed in the same manner as in Example 6-1 except that calcium carbonate having an average particle size of 4.0 μm was used as a seed crystal.

[Example 8-2]
Water softening was performed in the same manner as in Example 8-1, except that calcium carbonate was added so that the concentration became 100 ppm.

[Example 8-3]
Water softening was performed in the same manner as in Example 8-1, except that calcium carbonate was added so that the concentration was 500 ppm.

[Example 8-4]
Water softening was performed in the same manner as in Example 8-1 except that calcium carbonate was added so as to have a concentration of 1000 ppm.

[Example 9-1]
Water softening was performed in the same manner as in Example 6-1 except that calcium carbonate having an average particle size of 8.0 μm was used as a seed crystal.

[Example 9-2]
Water softening was performed in the same manner as in Example 9-1 except that calcium carbonate was added so as to have a concentration of 100 ppm.

[Example 9-3]
Water softening was performed in the same manner as in Example 9-1 except that calcium carbonate was added so as to have a concentration of 500 ppm.

[Example 9-4]
Water softening was performed in the same manner as in Example 9-1 except that calcium carbonate was added so as to have a concentration of 1000 ppm.

FIG. 10 shows a graph showing changes in pH with respect to the concentration of calcium carbonate in Examples 6-1 to 9-4. Similarly, FIG. 11 shows a graph showing the removal rate of calcium ions with respect to the concentration of calcium carbonate.

From FIG. 10, it can be seen that the smaller the average particle size of calcium carbonate or the higher the concentration, the faster the reaction and the lower the initial pH. Further, it can be seen from FIG. 11 that even if the concentration of calcium carbonate is low, the smaller the average particle size, the higher the removal rate of calcium ions.

The entire contents of Japanese Patent Application No. 2019-15435 (filing date: January 31, 2019) are hereby incorporated by reference.

According to the present embodiment, it is possible to provide a water softening device and a water softening method that can realize softening of hard water with a simple configuration.

10 11 Water softening device 12 13 Treatment tank 14 Treated water 16 pH adjusting unit 18 Seed crystal supply unit 20 Ultrasonic wave irradiating unit 22 Transducer

Claims

A treatment tank into which water to be treated, which is the target of water softening, is input,
A pH adjusting unit for adjusting the pH of the water to be treated,
A seed crystal supply unit for supplying a seed crystal of a hardness component to the water to be treated,
An ultrasonic wave irradiation unit for irradiating the water to be treated with ultrasonic waves,
And a water softening device.
The water softener according to claim 1, wherein the pH adjusted by the pH adjuster is 7.8 or higher.
The water softener according to claim 2, wherein the pH adjusted by the pH adjuster is 9.0 or higher.
The water softening device according to any one of claims 1 to 3, further comprising a temperature adjusting mechanism for adjusting the temperature of the water to be treated.
The water softening device according to any one of claims 1 to 4, wherein the seed crystal supplied by the seed crystal supply unit has a particle size of less than 2 µm.
The water softening device according to any one of claims 1 to 4, wherein the seed crystal supplied by the seed crystal supply unit has a particle size of 2 µm or more.
Step A of adjusting the pH of the water to be treated which is to be softened,
Step B for supplying a seed crystal of a hardness component to the water to be treated to be softened is included in no particular order,
A method of water softening, comprising a step C of irradiating the water to be treated with ultrasonic waves after performing both the step A and the step B.
The water softening method according to claim 7, wherein the pH of the water to be treated is adjusted to 7.8 or higher in the step A.
The water softening method according to claim 8, wherein in the step A, the pH of the water to be treated is adjusted to 9.0 or higher.
The water softening method according to any one of claims 7 to 9, wherein a buffer is supplied to the water to be treated in the step A.
The water softening method according to any one of claims 7 to 10, wherein seed crystals having an average particle size of less than 2 µm are supplied in the step B.
The water softening method according to any one of claims 7 to 10, wherein seed crystals having an average particle size of 2 µm or more are supplied in the step B.
The water softening method according to claim 11, wherein the concentration of the seed crystal in the water to be treated is 100 ppm or more and less than 500 ppm in the step B.
In the step B, the concentration of the seed crystal in the water to be treated is 500 ppm or more,
The water softening method according to claim 12.
The water softening method according to any one of claims 7 to 14, wherein in the step C, the temperature of the water to be treated is adjusted to be lower than 30°C.
The water softening method according to any one of claims 7 to 14, wherein in step C, the temperature of the water to be treated is adjusted to 30°C or higher.