WO2021117542A1

WO2021117542A1 - Water softener

Info

Publication number: WO2021117542A1
Application number: PCT/JP2020/044627
Authority: WO
Inventors: 隆好高野
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2019-12-12
Filing date: 2020-12-01
Publication date: 2021-06-17

Abstract

A water softener which is provided with: a hardness ion capturing unit which captures hardness ions by supplying a hardness ion scavenger to water to be processed, said water being the object of water softening; a flocculation unit which causes the hardness ion scavenger that has captured hardness ions to flocculate by supplying a flocculant to the water to be processed; and a filtration unit which filters a flocculation material that has been flocculated by the flocculant. With respect to this water softener, the hardness ion scavenger is a water-soluble anionic polymer that has a carboxyl group; and the flocculant is a cationic polymer.

Description

Water softener

The present invention relates to a water softening device.

Various forms of water softening equipment for softening hard water are known. Among them, a water softening device using an ion exchange resin is widely used, but has a problem. For example, if the water softening treatment is continued, the ion exchange capacity of the ion exchange resin gradually decreases. Therefore, it is necessary to regenerate the ion exchange resin after a predetermined treatment time has elapsed. In addition, it is necessary to use a large amount of salt in the regeneration process, and it has become a problem in recent years to give a load to the environment. Therefore, it is desired to realize a water softening device having a small load on the environment, and as one of the methods, a method applying the coagulation sedimentation method has been proposed. The method often consists of three main steps. For example, (1) a step of insolubilizing the hardness component dissolved in water, (2) a step of forming flocs of the insolubilized hardness components with a flocculant to coarsen them, and (3) precipitating or floating the flocs, and further. Is a three-step process of solid-liquid separation by filtration.

For example, in Patent Document 1, a reaction tank in which a carbonate root is added and an alkaline agent is added to adjust the pH to 12 to 13 to precipitate a hardness component in water, and a coagulation tank for coagulating the reaction solution from the reaction tank. It is composed of a settling tank that solid-liquid separates the coagulation treatment liquid from the coagulation tank.

Further, Patent Document 2 proposes a method of adding sodium carbonate to calcium-containing wastewater, precipitating calcium carbonate, adding a flocculant, and further separating suspended solids by sedimentation, a filter, and a filter press. ing.

In the methods of Patent Documents 1 and 2, it is not necessary to perform a regeneration process unlike an ion exchange resin. Therefore, the salt used for the regeneration treatment is unnecessary, and it is considered that the load on the environment is small.

Japanese Unexamined Patent Publication No. 2015-112593 Japanese Unexamined Patent Publication No. 2016-16341

However, in both Patent Documents 1 and 2, since the hardness component is precipitated and removed as a carbonate, it is strongly affected by the concentration of hardness ions contained in water. For example, in the case of hard water having a relatively low hardness, the hardness ion concentration is low, which makes it difficult to precipitate a hardness component. Therefore, it is difficult to stably perform the softened water treatment. Further, if the hardness of the raw water fluctuates, the degree of precipitation also becomes unstable, and it becomes difficult to stably soften the water.

From the above, there is a low environmental load method that removes hardness components such as calcium and magnesium dissolved in the water to be treated without the need for salt regeneration, which is required for ion exchange resins. However, the structure of the system has a problem that it is affected by the hardness ion concentration in the raw water because the hardness component is precipitated as a carbonate or the like.

The present invention has been made in view of the problems of the prior art. An object of the present invention is to provide a water softening apparatus capable of stably softening water with a small load on the environment and little influence of the hardness ion concentration in raw water.

In order to solve the above problems, the water softening apparatus according to the aspect of the present invention includes a hardness ion trapping unit that supplies a hardness ion trapping agent into the water to be treated to be water softened and traps the hardness ions. The treatment water is provided with an aggregating portion for supplying the aggregating agent to agglomerate the hardness ion trapping agent that has captured the hardness ions, and a filtering portion for filtering the agglomerates aggregated by the aggregating agent. It is a water-soluble anionic polymer having a group, and the flocculant is a cationic polymer.

It is a block diagram which shows the whole structure of the water softening apparatus which concerns on 1st Embodiment. It is a block diagram which shows the whole structure of the water softening apparatus which concerns on 2nd Embodiment. It is a graph which shows the total hardness with respect to the polyacrylic acid concentration measured in an Example. It is a graph which shows the total hardness with respect to the hardness ion scavenger concentration measured in an Example.

Hereinafter, the water softening apparatus of this embodiment will be described with reference to the drawings. The dimensional ratios in the drawings are exaggerated for convenience of explanation and may differ from the actual ratios.

The water softening device of the present embodiment includes a hardness ion trapping unit that supplies a hardness ion trapping agent to the water to be treated to be softened and traps the hardness ions. Further, the water to be treated is provided with an aggregating portion for supplying the aggregating agent to agglomerate the hardness ion scavenger that has captured the hardness ions. Further, it is provided with a filtration unit for filtering the agglomerates aggregated by the aggregating agent. The hardness ion scavenger is a water-soluble anionic polymer having a carboxyl group, and the flocculant is a cationic polymer.

In the water softening device of the present embodiment, first, hardness ions are captured by a hardness ion scavenger. Next, the hardness ion scavenger that has captured the hardness ions is aggregated to form an agglomerate. Then, the produced agglomerates are filtered for solid-liquid separation. That is, in the present embodiment, the hardness ions are not aggregated after being made into a carbonate or the like, but are captured by a polymer hardness ion scavenger and aggregated together with the hardness ion scavenger. Therefore, as long as the hardness ions are captured by the hardness ion scavenger, they can be easily aggregated. Therefore, even when the hardness ion concentration is low, the hardness ions can be removed, and by extension, the water can be softened almost without being affected by the concentration of the hardness ions.

<First Embodiment>
As shown in FIG. 1, the water softening device 10 of the first embodiment includes three main configurations of a hardness ion trapping unit 12, an agglomerating unit 14, and a filtering unit 16, each of which is connected by a pipe 18. .. Then, the hardness ion scavenger 12 supplies a hardness ion scavenger to the water to be treated, and the hardness ion scavenger captures the hardness ions. Next, in the agglomerating portion 14, the hardness ion scavenger that has captured the hardness ions is agglomerated by the aggregating agent to form agglomerates (coarse particles). Then, the agglomerates in the water to be treated are filtered by the filtration unit 16 and separated into solid and liquid. As described above, hardness ions are removed from the water to be treated to soften the water.
Hereinafter, each configuration of the water softening device of the present embodiment will be sequentially described.

[Hardness ion trapping unit]
The hardness ion scavenger 12 supplies a hardness ion scavenger into the water to be treated to capture the hardness ions. The hardness ion scavenger is a water-soluble anionic polymer having a carboxyl group, and hardness ions are bonded to the carboxyl group.

As described above, the hardness ion scavenger is a water-soluble anionic polymer having a carboxyl group, and has a property of complexing with calcium ions and magnesium ions, which are hardness components. That is, the hardness ion scavenger captures the hardness component by forming a complex with the hardness component in the water to be treated.
The weight average molecular weight of the hardness ion scavenger is preferably 25,000 to 1,000,000, more preferably 25,000 to 250,000. When the weight average molecular weight of the hardness ion scavenger becomes large, the molecular chain becomes long and easily aggregates. However, as the weight average molecular weight of the hardness ion scavenger increases, the hydrophobic property tends to become stronger, and it becomes difficult to dissolve in water. Therefore, considering the water solubility of the hardness ion scavenger, the weight average molecular weight is preferably 250,000 or less.
The water-soluble means that the solubility in neutral water at room temperature is 10 g / L or more. Further, it is preferable that the hardness ion scavenger does not gel.

Specifically, the hardness ion scavenger used in the present embodiment is preferably at least one selected from the group consisting of polyacrylic acid, polyacrylic acid salt, and pectin. These hardness ion scavengers may be used alone or in combination of two or more.

In the present embodiment, the hardness ion trapping unit 12 can be in the form of a tank in which the water to be treated is temporarily stored or a similar form. Further, the mechanism for supplying the hardness ion scavenger into the tank is not particularly limited. For example, when the hardness ion scavenger is an aqueous solution, it can be quantitatively supplied to the water to be treated by a known liquid supply mechanism. When the hardness ion scavenger is powder, it can be supplied as powder to the water to be treated by using a feeder or the like.

The amount of the hardness ion scavenger added to the hardness ion scavenger 12 may be appropriately adjusted according to the flow velocity of the water to be treated or the amount of the hardness component, but it is preferably added at a flow rate of, for example, 500 to 1000 mg / L.

[Aggregate part]
The water to be treated that has passed through the hardness ion trapping portion 12 is guided to the agglomerating portion 14. In the agglomerating section 14, a flocculant for aggregating the hardness ion scavenger that has captured the hardness ions generated by the hardness ion scavenging section 12 is supplied, and an agglomerate of the hardness ion scavenger is generated. That is, in the agglomeration portion 14, the hardness ions are agglomerated together with the hardness ion scavenger to form an agglomerate.

In the water softening device of the present embodiment, when the softened water is used as household water, a cationic polymer is preferable as the coagulant. The cationic polymer is preferably at least one selected from the group consisting of chitosan, polyamine, polydiallyldimethylammonium chloride, and polydicyandiamide. One of these flocculants may be used alone, or two or more thereof may be used in combination.

In the present embodiment, the form of the aggregating portion 14 does not matter as long as the aggregating agent can be supplied to agglomerate the hardness ion scavenger. Similar to the hardness ion trapping unit 12, the agglomerating unit 14 may have a tank in which water to be treated is temporarily stored or a similar form. Further, the mechanism for supplying the flocculant into the tank is not particularly limited. For example, when the flocculant is an aqueous solution, it can be quantitatively supplied to the water to be treated by a known liquid supply mechanism. When the coagulant is powder, it can be supplied as powder to the water to be treated by using a feeder or the like.

The amount of the aggregating agent added to the aggregating portion 14 may be appropriately adjusted according to the flow velocity of the water to be treated or the amount of the hardness component, but it is preferable to add the aggregating agent at a flow rate of, for example, 150 to 3000 mg / L.

In the present embodiment, the mass ratio of the hardness ion scavenger and the aggregating agent supplied into the water to be treated is preferably 3: 1 to 1: 3 from the viewpoint of efficiently aggregating the hardness components.

[Filtration section]
The water to be treated that has passed through the agglomerating portion 14 is guided to the filtering portion 16. In the filtration unit 16, the agglomerates generated in the agglutinating unit 14 are filtered from the water to be treated for solid-liquid separation. That is, since the agglomerates containing the hardness component of the water to be treated that has passed through the filtration unit 16 do not pass through the filter medium in the filtration unit 16, the filtered water to be treated becomes soft water.

In the present embodiment, the filtration unit 16 may be in any form as long as it can filter the agglomerates and separate the solid and liquid. Hereinafter, the filtration unit 16 using the granular filter medium will be described, but the present embodiment is not limited thereto.

In the filtration part using the granular filter medium, the granular filter medium is intended to capture and remove the agglomerates. However, particles having a surface potential that are adsorbed on the granular filter medium, particles having a particle diameter of about 1 to 10 μm, and chromaticity can be removed depending on the presence of ions in the water to be treated. As the granular filter medium, a filter medium suitable for the object to be removed, such as filtered sand or a pellet-shaped fiber filter medium, can be used. The material of the granular filter medium may be, for example, sand, anthracite, garnet, ceramics, granular activated carbon, iron oxyhydroxide, manganese sand, or the like, as long as it has a hardness that allows it to settle in water and is not easily deformed by pressure. It is preferable to use a particle size having a particle size of, for example, 0.3 to 5.0 mm and a uniformity coefficient of 1.2 to 2.0.

The specific gravity of the granular filter medium differs depending on the material, for example, about 2.5 to 2.7 g / cm ³ for sand, 1.4 to 1.8 ^{g / cm 3 for anthracite, and 3} for garnet. It is .8 to 4.1 g / cm ³ . The multi-layer filtration method in which a plurality of types of filter media are mixed and used is a method in which particles having different sizes are laminated in order from the bottom as a layer to be filtered by utilizing such a difference in specific densities. In the multi-layer filtration method, it is common to mix particles having a large specific density and a small size and particles having a small specific density and a large size to form a multi-layer structure. The multi-layer filtration method is preferable because it has advantages such as high filtration efficiency per unit volume and low head loss as compared with using a single type of filter medium. As the granular filter medium, for example, 0.3 mm of garnet, 0.6 mm of sand, and 1.0 mm of anthracite are mixed at a ratio of 2: 1: 1 and used, depending on the particle characteristics of the turbidity. It is desirable to adjust the mixing ratio and particle size.

<Second embodiment>
The water softening device of the second embodiment is the water softening device of the first embodiment, in which a backwash line for washing aggregates adhering to the filter medium in the filtration unit by backwashing water and a reverse washing line for washing the filter medium are completed. It is a form further provided with a settling tank for precipitating agglomerates in washing water. Since agglomerates derived from the hardness ion scavenger adhere to the filter medium of the filtration part, there is a concern that the filtration performance may deteriorate over time. Therefore, in the second embodiment, a backwashing line is provided, and a settling tank for washing the filter medium of the filtration unit by backwashing and precipitating agglomerates generated by the washing is provided.

FIG. 2 is a block diagram showing the overall configuration of the water softening device 11 of the second embodiment. The water softening device 11 shown in FIG. 2 is different from the water softening device 10 shown in FIG. 1 in that a backwash line is mainly provided. Therefore, the same components in the water softening apparatus 10 shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted.

In the water softening device 11 shown in FIG. 2, a backwash line 22 is connected to the filtration unit 16. The backwash line 22 has a water source for backwash water (not shown) on the upstream side so that the wash water flows in the direction opposite to the flow direction of the water to be treated (in the direction of the arrow in FIG. 2) during the softening treatment. )It is connected to the. Then, the backwash water flowing out from the water source flows into the filtration unit 16, cleans the internal filter medium, and flows out from the side opposite to the inflow port of the filtration unit 16. Further, the backwash line 22 located on the downstream side of the filtration unit 16 is provided with a settling tank 20 for precipitating agglomerates separated from the filter medium in the filtration unit 16 by backwashing.

As described above, the flow direction of the backwash water introduced into the filter unit 16 from the backwash line 22 with respect to the filter medium of the water to be treated, which passes through the agglomerate unit 14 and is introduced into the filter unit 16, is opposite to the flow direction of the water to be treated. Is. That is, the flow direction of the water to be treated introduced from the backwash line 22 to the filtration unit 16 is the direction in which the agglomerates adhering to the filter medium are separated.

The settling tank 20 is a tank for settling and separating larger agglomerates among the agglomerates separated from the filter medium. That is, the washing water that has passed through the settling tank 20 is in a state in which larger agglomerates have been removed. Therefore, clogging of the piping on the downstream side of the settling tank 20 can be suppressed.

The settling tank 20 is preferably provided with a discharge section for discharging the precipitated agglomerates, and the settling tank 20 shown in FIG. 2 includes a settling section 20A and a discharge section 20B. The settling portion 20A is a portion for precipitating a larger agglomerate among the agglomerates in the passing washing water. The discharge unit 20B is a portion for discharging the agglomerates precipitated in the sedimentation unit 20A to the outside. In the discharge unit 20B, the large aggregates that have settled can be easily discharged to the outside, which facilitates maintenance.
The settling tank 20 including the settling section 20A and the discharging section 20B as described above can be formed into the settling section 20A and the discharging section 20B by providing an opening at the bottom or the bottom of one tank.

On the other hand, as shown in FIG. 2, the water softening device 11 has a sustained-release portion that gradually supplies a hardness ion scavenger and a flocculant (hereinafter, these may be collectively referred to as “drug”). You may be doing it. Specifically, the hardness ion scavenger 12 is provided with the hardness ion scavenger sustained release unit 13, and the agglomerating unit 14 is provided with the aggregating agent sustained release unit 15. Then, the hardness ion scavenger sustained release unit 13 gradually supplies the hardness ion scavenger to the hardness ion scavenger unit 12. Further, the coagulant sustained release unit 15 gradually supplies the coagulant to the coagulant unit 14. By providing such a hardness ion scavenger sustained release portion 13 and a flocculant sustained release portion 15 (hereinafter, these may be collectively referred to as a “sustained release portion”), hardness ions are generated with respect to the water to be treated. A constant amount of each of the scavenger and the flocculant can be stably supplied over a long period of time. Each sustained-release unit may supply the drug continuously or intermittently.

When the hardness ion scavenger or flocculant can be solidified and the solid drug has sustained release properties, a sustained release portion in the form of passing water to be treated through the solid drug is configured. May be good. In that configuration, the solid drug can function as a sustained release portion by being gradually released by passing water.

Both the hardness ion scavenger sustained release unit 13 and the flocculant sustained release unit 15 may be configured to gradually supply the respective agents by electrical control. According to such a configuration, for example, each drug can be gradually released only when the water to be treated is passed through the hardness ion trapping portion and / or the agglomerating portion. Therefore, since the chemicals are slowly released only when the water to be treated is passed, each chemical can be efficiently supplied without wasting it.
Further, when the water to be treated is started to pass through, both the flocculant and the hardness ion scavenger are supplied at the same timing, or the flocculant is supplied at a timing later than that of the hardness ion scavenger. You can also do it. Similarly, when the water to be treated is stopped, the supply of both the flocculant and the hardness ion scavenger is stopped at the same timing, or the supply of the flocculant is stopped at a timing later than that of the hardness ion scavenger. It can also be. In any of the configurations, wasteful consumption of the drug is small and the drug can be efficiently supplied.

In the above first and second embodiments, the hardness ion trapping portion and the agglutinating portion are provided separately, but a hardness ion capturing portion and the agglutinating portion may be provided for one tank. In that case, the hardness ions are captured by the hardness ion scavenger and the hardness ion scavenger is aggregated by the flocculant in one tank.
Further, since it is ideal that the hardness ion scavenger captures the hardness component and then agglomerates with the aggregating agent, the order of supplying the hardness ion scavenger and the aggregating agent may be the order of the hardness ion scavenger and the aggregating agent. preferable.

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

Hereinafter, the operation of the water softening device in the present embodiment will be described in more detail with reference to Examples, but the present embodiment is not limited to these Examples.

[Example 1]
In order to confirm the water softening ability of the water softening apparatus of the present embodiment, treatments were sequentially performed in each of the hardness ion trapping part, the agglomerating part and the filtering part in the beaker as follows.

Polyacrylic acid (average molecular weight: 5,000) was used as a hardness ion scavenger, chitosan was used as a flocculant, and a syringe filter was used as a filter. First, 100 g of Evian (manufactured by Danone Japan Co., Ltd.) was put into the beaker as hard water (water to be treated). Then, while stirring the hard water with a stirrer, polyacrylic acid and chitosan were added in this order. At this time, the concentrations of polyacrylic acid and chitosan were both added so as to be 100 ppm. Then, water was collected with a syringe and filtered with a syringe filter. Further, the above operation was also performed when the polyacrylic acid concentration and the chitosan concentration were added so as to be 250 ppm, 500 ppm, and 1000 ppm.

The total hardness of the water treated as described above was measured by the chelatometric titration method. The measurement results are shown in the graph of FIG.

[Example 2]
Hard water was treated in the same manner as in Example 1 except that the polyacrylic acid was changed to one having a weight average molecular weight of 25,000, and the total hardness of the treated water was measured. The measurement results are shown in the graph of FIG.

[Example 3]
Hard water was treated in the same manner as in Example 1 except that the polyacrylic acid was changed to one having a weight average molecular weight of 250,000, and the total hardness of the treated water was measured. The measurement results are shown in the graph of FIG.

[Example 4]
Hard water was treated in the same manner as in Example 1 except that the polyacrylic acid was changed to one having a weight average molecular weight of 1,000,000, and the total hardness of the treated water was measured. The measurement results are shown in the graph of FIG.

From the graph of FIG. 3, in any of Examples 1 to 4, the total hardness of the treated water decreased as the polyacrylic acid concentration was increased. That is, it was shown that the water softening treatment can be performed by the water softening device of the present embodiment. However, when the concentration of polyacrylic acid was 500 ppm or more, no decrease in hardness was observed even if the added concentration was further increased. It is presumed that this is because the pH decreased due to the increase in the concentration of polyacrylic acid, and the carboxyl group and the hardness ion stopped reacting.
Further, from the comparison of Examples 1 to 4 in which polyacrylic acids having different weight average molecular weights are used, the larger the weight average molecular weight of polyacrylic acid, the larger the decrease in total hardness, which is advantageous for hardness treatment. I understand.

[Example 5]
Hard water was treated in the same manner as in Example 1 except that the polyacrylic acid was changed to pectin and the concentration of chitosan was set to 1/2 of that of pectin, and the total hardness of the treated water was measured. .. The measurement results are shown in the graph of FIG.

[Example 6]
Hard water was treated in the same manner as in Example 1 except that the polyacrylic acid was changed to sodium polyacrylate (degree of polymerization: 2,700 to 7,500), and the total hardness of the treated water was measured. The measurement results are shown in the graph of FIG.

[Example 7]
Hard water was treated in the same manner as in Example 1 except that the polyacrylic acid was changed to sodium polyacrylate (degree of polymerization: 22,000 to 77,000), and the total hardness of the treated water was measured. The measurement results are shown in the graph of FIG.

From FIG. 4, in any of Examples 5 to 7, the total hardness of the treated water decreased as the concentration of each hardness ion scavenger was increased. Therefore, hardness treatment can be performed using these hardness ion scavengers. However, there is a difference in the amount of decrease in total hardness, and it can be seen that Example 6 using sodium polyacrylate having a high degree of polymerization has the largest decrease and is advantageous. On the contrary, in Example 5 using pectin, it was found that the amount of decrease in total hardness was small, and a high concentration was required even if the same hardness treatment was applied. In Example 5 using pectin, water could not be passed through the syringe filter, so filtration was not performed, but it is considered that there is no effect on the measurement of the total hardness.

The entire contents of Japanese Patent Application No. 2019-224537 (application date: December 12, 2019) are incorporated here.

According to the present disclosure, it is possible to provide a water softening device capable of stably softening water with a small load on the environment and little influence of the hardness ion concentration in raw water.

10 11 Water softening device 12 Hardness ion trapping part 14 Aggregating part 16 Filtration part 18 Piping 20 Sedimentation tank

20A Sedimentation part

20B Discharge part 22 Backwash line

Claims

A hardness ion scavenger that captures hardness ions by supplying a hardness ion scavenger into the water to be treated to be softened.
An aggregating portion that supplies an aggregating agent to the water to be treated to agglomerate the hardness ion scavenger that has captured the hardness ions.
A filtration unit that filters the aggregates aggregated by the flocculant, and
With
A water softening device in which the hardness ion scavenger is a water-soluble anionic polymer having a carboxyl group and the flocculant is a cationic polymer.
The water softening device according to claim 1, wherein the hardness ion scavenger has a weight average molecular weight of 25,000 to 1,000,000.
The water softening apparatus according to claim 1 or 2, wherein the hardness ion scavenger is at least one selected from the group consisting of polyacrylic acid, polyacrylate, and pectin.
The water softening apparatus according to any one of claims 1 to 3, wherein the flocculant is at least one selected from the group consisting of chitosan, polyamine, polydiallyldimethylammonium chloride, and polydicyandiamide.
Claim 1 to further include a backwash line for washing the agglomerates adhering to the filter medium in the filter medium with backwash water, and a settling tank for precipitating the agglomerates in the backwash water after washing the filter medium. The water softening apparatus according to any one of 4.
The water softening device according to claim 5, wherein the settling tank is provided with a discharge unit for discharging the settled agglomerates.