JP2019013862A - Water treatment method and water treatment device - Google Patents

Abstract

To provide a water treatment method and a water treatment device possible to remove haloacetic acid produced in the treatment of water to be treated, even if organic substances and ammonia in the water to be treated are not removed by pretreatment.SOLUTION: There are provided a water treatment method and a water treatment device 1 for removing haloacetic acid by bringing water to be treated containing the haloacetic acid produced by adding hypochlorite into contact with an anion exchanger. The water treatment method includes: an adding step of adding hypochlorite to the water to be treated; and an ion exchange treatment step of bringing water to be treated to which hypochlorite has been added into contact with an anion exchanger. The water treatment device 1 includes: adding means 30 for adding the hypochlorite to the water to be treated; and ion exchange treatment means 50 for bringing the water to be treated to which hypochlorite has been added into contact with an anion exchanger.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a water treatment method and a water treatment apparatus.

To drink treated water such as groundwater and well water, it is necessary to remove inorganic ions such as iron and manganese, organic substances mainly composed of ammonia, humic acid and fulvic acid contained in the treated water. .
Treatment of water to be treated is usually performed by adding hypochlorite such as sodium hypochlorite (NaClO) to the water to be treated.

  However, it is known that when hypochlorite is added to the water to be treated, disinfection by-products such as haloacetic acid and trihalomethane are generated by the reaction between organic substances in the water to be treated and hypochlorite ( For example, refer nonpatent literature 1). In particular, when the ammonia concentration in the water to be treated is high, the above-mentioned disinfection by-product is generated by the reaction of excess hypochlorite and organic matter in addition to oxidation of iron, manganese and ammonia and decomposition of organic matter. The direct reason is that about 10 equivalents or more of hypochlorite must be added for the decomposition of ammonia into nitrogen. Therefore, the amount of hypochlorite added increases and the amount of disinfection by-products increases. As a result, when the disinfection by-product is generated, it may be unsuitable as drinking water, so it is desirable to remove the disinfection by-product from the water to be treated.

  As a water purifier for removing trihalomethane in water to be treated, a water purifier has been proposed in which a cartridge made of an activated carbon molded body obtained by molding a mixture of fibrous activated carbon, powdered activated carbon, and fibrous binder is filled in a housing ( For example, see Patent Document 1).

Sugino, et al., “Formation of chloroacetic acid and chloral hydrate in chlorination of humic substances in water”, Water Pollution Research, 1986, Vol. 9, No. 7, p. 437-444

JP 2005-13883 A

As described in Patent Document 1, trihalomethane is easily adsorbed on activated carbon and is easily removed from water to be treated.
However, since haloacetic acid is a hydrophilic molecule, it is difficult to be adsorbed on activated carbon and difficult to remove from the water to be treated. In order to increase the adsorption amount of haloacetic acid, it is conceivable to increase the amount of activated carbon used, but in that case, an apparatus for accommodating excess activated carbon is required.

Until now, there were few useful means for removing haloacetic acid from water to be treated.
Therefore, before adding hypochlorite, as a pretreatment, flocculants such as polyaluminum chloride and aluminum sulfate are added and activated carbon treatment removes organic matter in the water to be treated, or reverse osmosis at the expense of drainage costs. The amount of disinfection by-products was suppressed by desalting with (RO) equipment or decomposing ammonia in the water to be treated by biological treatment to reduce the amount of hypochlorite added.

  The present invention has been made in view of the above circumstances, and a water treatment method and water capable of removing haloacetic acid generated in the treatment of water to be treated without removing organic matter and ammonia in the water to be treated by pretreatment. It is an object to provide a processing apparatus.

The present invention has the following aspects.
[1] A water treatment method in which water to be treated containing haloacetic acid produced by addition of hypochlorite is brought into contact with an anion exchanger to remove haloacetic acid.
[2] An addition step of adding hypochlorite to the water to be treated, and an ion exchange treatment step of bringing the water to be treated to which hypochlorite has been added into contact with the anion exchanger, [1] ] The water treatment method as described in.
[3] The method further includes an activated carbon treatment step in which activated water is brought into contact with water to be treated to which the hypochlorite is added, and the ion exchange treatment step and the activated carbon treatment step are performed simultaneously, or the ion exchange treatment step is performed. The water treatment method according to [2], which is performed after the activated carbon treatment step.
[4] The water treatment method according to any one of [1] to [3], wherein the treated water is groundwater or well water.
[5] Any one of [1] to [4], wherein the total organic carbon (TOC) is 1 ppm or more and the water to be treated to which 10 ppm or more of hypochlorite is added is brought into contact with the anion exchanger. The water treatment method as described in any one of.

[6] A water treatment apparatus for removing haloacetic acid produced when water treatment is performed by adding hypochlorite to water to be treated, the addition means for adding hypochlorite to water to be treated; A water treatment apparatus comprising: ion-exchange treatment means for bringing water to be treated added with hypochlorite into contact with an anion exchanger.
[7] The apparatus further includes activated carbon treatment means for bringing the water to be treated to which the hypochlorite is added into contact with activated carbon, and the ion exchange treatment means and the activated carbon treatment means are configured as one treatment means, or The water treatment apparatus according to [6], wherein the ion exchange treatment means is provided downstream of the activated carbon treatment means.
[8] The water treatment apparatus according to [6] or [7], wherein the treated water is groundwater or well water.

  According to the water treatment method and the water treatment apparatus of the present invention, haloacetic acid generated in the treatment of water to be treated can be removed without removing organic matter and ammonia in the water to be treated by pretreatment.

It is the schematic which shows an example of the water treatment apparatus of this invention.

Hereinafter, the present invention will be described in detail with reference to the drawings.
In the following drawings, the scale of each member is appropriately changed to make each member a recognizable size.

Examples of the haloacetic acid to be removed in the present invention include monohaloacetic acid such as chloroacetic acid and bromoacetic acid and salts thereof; dihaloacetic acid such as dichloroacetic acid, dibromoacetic acid and bromochloroacetic acid and salts thereof; trichloroacetic acid, tribromoacetic acid and bromodichloro And polyhalogenoacetic acid such as acetic acid, trihaloacetic acid such as dibromochloroacetic acid and salts thereof. Examples of the salt include sodium salt, calcium salt, magnesium salt and the like.
Haloacetic acid tends to increase in proportion to the product of the amount of hypochlorite added to the water to be treated and the content of organic matter in the water to be treated. Among organic substances, particularly when the content of humic substances having a phenol skeleton is high, disinfection by-products tend to increase, but the haloacetic acid generation mechanism is not clarified.

Examples of water to be treated according to the present invention include groundwater, well water, leachate, river water, lake water, and the like. In particular, when groundwater or well water is treated, the amount of hypochlorite added is larger than when treating river water, so disinfection by-products such as haloacetic acid tend to be generated. . Therefore, the present invention is particularly suitable when the water to be treated is groundwater, well water, or lake water.
The following embodiment is a case where treated water is groundwater.

"Water treatment equipment"
FIG. 1 shows an example of the water treatment apparatus of the present invention.
A water treatment apparatus 1 shown in FIG. 1 includes, in order from the upstream side, a pumping means 10 that pumps up groundwater W as treated water from a well A, a storage tank 20 that temporarily stores groundwater W pumped up from a well A, and groundwater W An addition means 30 for adding hypochlorite, an activated carbon treatment means 40 for bringing the groundwater W added with hypochlorite into contact with the activated carbon, an anion exchange with the groundwater W added with hypochlorite An ion exchange treatment means 50 for contacting the body, a treated water tank 60 for storing treated ground water (hereinafter also referred to as “treated water”), and an adding means for adding hypochlorite to the treated water again. 70.
In the present invention, the addition means 30 for adding hypochlorite to the groundwater before contacting with the anion exchanger is also referred to as “first addition means 30”, and the groundwater treated with the anion exchanger ( The addition means 70 for adding hypochlorite to the treated water) is also referred to as “second addition means 70”.

The pumping means 10 is for pumping up groundwater W as treated water from the well A, and includes a pumping pump 11 for pumping up the groundwater W and a pumping pipe 12.
One end of the pumping pipe 12 in this example is connected to the pumping pump 11, and the other end is connected to the storage tank 20.

The storage tank 20 temporarily stores the groundwater W pumped from the well A. The groundwater W pumped up from the well A passes through the pumping pipe 12 and is stored in the storage tank 20.
The groundwater W stored in the storage tank 20 passes through the first water pipe 21 and is supplied to the activated carbon treatment means 40.

An addition means 30 (first addition means 30) for adding hypochlorite to the ground water W is connected to the first water pipe 21.
The first addition means 30 includes a first storage tank 31 that stores hypochlorite and a first supply pipe 32 that supplies hypochlorite to the first water pipe 21. In the present embodiment, the first supply pipe 32 joins in the middle of the first water pipe 21, and hypochlorite is supplied to the groundwater W in the first water pipe 21. ing.
Examples of hypochlorite include sodium hypochlorite and calcium hypochlorite. Among these, sodium hypochlorite is preferable from the viewpoints of cost, reaction rate, non-metal oxidant, and flowability.

The activated carbon treatment means 40 is for bringing the groundwater W to which hypochlorite is added into contact with the activated carbon.
The activated carbon treatment means 40 of this embodiment includes an activated carbon adsorption tower 41 filled with activated carbon.
A first water pipe 21 is connected to the upper part of the activated carbon adsorption tower 41.

The ion exchange treatment means 50 makes the ground water W added with hypochlorite and the anion exchanger come into contact with each other.
The ion exchange processing means 50 of this embodiment includes an ion exchanger column 51 filled with an anion exchanger. The ion exchanger tower 51 is provided with a filter 52 that prevents the anion exchanger from flowing out.
The groundwater W that has passed through the activated carbon treatment means 40 is discharged from the lower end of the activated carbon adsorption tower 41, passes through the second water conduit 42, and is supplied to the ion exchange treatment means 50. One end of the second water pipe 42 is connected to the lower part of the activated carbon adsorption tower 41, and the other end is connected to the upper part of the ion exchanger tower 51.

The ion exchanger column 51 is packed with an anion exchanger so as to form a fixed bed or a fluidized bed.
The anion exchanger has ion exchange groups (fixed ions) chemically bonded to the backbone polymer on the surface and inside of the backbone polymer (resin matrix). By this ion exchange group, haloacetic acid and organic matter in the groundwater W are adsorbed, and the haloacetic acid and organic matter can be removed from the groundwater W.
Examples of the skeleton polymer include polymers such as styrene, (meth) acrylic, (meth) acrylamide, and cellulose. Among these, from the viewpoint of organic contamination resistance, (meth) acrylic and (meth) acrylamide polymers that are hydrophilic polymers are preferable, and styrene polymers are preferable from the viewpoint of cost.

The anion exchanger may be weakly basic or strong basic, but a strong basic anion exchanger is preferred in that haloacetic acid and organic substances are easily adsorbed.
Here, the “strongly basic anion exchanger” is an anion exchanger having a quaternary ammonium group that is alkaline but in a dissociated state as an ion exchange group.

  Examples of the strongly basic anion exchanger include those having various ion exchange groups. Examples of the ion exchange group include a trimethylammonium group, a triethylammonium group, a tripropylammonium group, a tributylammonium group, a hydroxyethyldimethylammonium group, a dihydroxyethylmethylammonium group, and the like. Among these, maximization of static exchange capacity, increase in the amount of organic substances accompanying elution due to poor thermal stability of ion exchange groups, generation of odors derived from ion exchange groups, ion exchange groups due to long-term use From the standpoint of the generation of formaldehyde accompanying the removal of the ion exchange group and the decomposition of the ion exchange group, the ion exchange group is preferably a trimethylammonium group.

Examples of the anion exchanger include anion exchange resins and anion exchange fibers.
A larger particle size of the anion exchange resin is preferable from the viewpoint of suppressing an increase in the pressure loss of the resin. The average particle diameter of the anion exchange resin is preferably 100 μm or more, more preferably 200 μm or more, and further preferably 300 μm or more.
On the other hand, from the viewpoint of minimizing the adsorption zone length and maximizing the flow-through exchange capacity, it is preferable that the particle diameter of the anion exchange resin is small. The average particle diameter of the anion exchange resin is preferably 800 μm or less, more preferably 700 μm or less, still more preferably 600 μm or less, and particularly preferably 500 μm or less.
The anion exchange resin may be a resin having a particle size distribution or a resin having a uniform particle size with a uniform particle size.
When a strongly basic anion exchange resin is used as the anion exchange resin, the strong base anion exchange resin may be of type I or type II.

  Commercially available anion exchange resins can be used, such as Amberlite “IRA402”, “IRA901”, “XT5007”, “IRA958”, “IRA938”, “IRA458” manufactured by The Dow Chemical Company, Dowex Marathon “A”, “SBR”, “MSA”, “MSA-1”, “C”, “C-1”; Lebatit “MP500”, “M500”, “MP504”, “A8071” manufactured by LANXESS "Indion A930" manufactured by AEON EXCHANGE INDIA, Inc. "Vankou ZGD730" manufactured by Hangzhou Conflict Resin Co., Ltd .; Diaion "SA10A", "SA12A", "PA308" manufactured by Mitsubishi Chemical Corporation, and Rewrite “JA800”, “JA810” and the like are preferable.

The fiber constituting the anion exchange fiber may be a short fiber or a long fiber. The anion exchange fiber may be a graft polymerization type.
The average fiber diameter of the anion exchange fiber is preferably 1 μm or more, more preferably 10 μm or more. The average fiber diameter of the anion exchange fiber is preferably 1 mm or less, more preferably 500 μm or less, still more preferably 100 μm or less, and particularly preferably 50 μm or less.
A commercially available product can be used as the anion exchange fiber, and for example, “IEF-SA” manufactured by Nichibi Corporation is suitable.

Groundwater W (treated water) that has passed through the ion exchange treatment means 50 is discharged from the lower end of the ion exchanger tower 51, passes through the third water conduit 53, and is stored in the treated water tank 60. One end of the third water pipe 53 is connected to the lower part of the ion exchanger tower 51, and the other end is connected to the treated water tank 60.
The treated water tank 60 is connected to a treated water supply pipe 61 for supplying to a water receiving tank (not shown).

An addition means 70 (second addition means 70) for adding hypochlorite to the ground water W (treated water) that has passed through the ion exchange treatment means 50 is connected to the third water pipe 53. .
The second addition means 70 includes a second storage tank 71 that stores hypochlorite, and a second supply pipe 72 that supplies hypochlorite to the third water pipe 53. In the present embodiment, the second supply pipe 72 joins in the middle of the third water pipe 53, and hypochlorite is supplied to the treated water in the third water pipe 53. ing.
The first storage tank 31 and the second storage tank 71 may be shared.

  In addition, when groundwater W contains iron or manganese, a sand filtration tower (not shown) filled with sand such as filtration sand, filtration gravel, manganese sand, manganese dioxide particles is installed upstream of the activated carbon treatment means 40. It is desirable to do.

"Water treatment method"
Hereinafter, an example of the water treatment method of groundwater using the water treatment apparatus 1 shown in FIG. 1 will be described.
First, the pumping pump 11 is operated to draw up the ground water W from the well A. The groundwater W pumped up is supplied to the storage tank 20 through the pumping pipe 12 and temporarily stored.

The groundwater W stored in the storage tank 20 is supplied to the activated carbon treatment means 40 through the first water pipe 21. When the groundwater W passes through the first water pipe 21, hypochlorite is added to the groundwater W at the junction of the first water pipe 21 and the first supply pipe 32 (addition process). . In addition, when iron and manganese are contained in the groundwater W, if a sand filtration tower (not shown) is installed upstream of the activated carbon treatment means 40, the iron precipitated by oxidation with hypochlorite is filtered. The Furthermore, if the sand filtration tower is filled with manganese sand, manganese is removed by catalytic oxidation with manganese sand.
The required amount of hypochlorite depends on the concentration of iron, manganese, ammonia, and organic matter in the groundwater W. In particular, the influence of ammonia concentration is great, and it is preferable to add 10 equivalents or more of hypochlorite to oxidize ammonia to nitrogen. However, the amount of hypochlorite added is preferably as small as possible from the viewpoints of by-production of haloacetic acid and economy.
When total organic carbon (TOC) in groundwater W is 1 ppm or more and the amount of hypochlorite added is 10 ppm or more with respect to 1 liter of groundwater W, there is a tendency that haloacetic acid and trihalomethane are likely to be generated. In addition, when the total organic carbon is 1.5 ppm or more and the amount of hypochlorite added is 20 ppm or more, the tendency is remarkable.
Although the formation mechanism of haloacetic acid is not clarified, the phenol skeleton components in humic acid and fulvic acid are oxidized by chlorine radicals to produce haloacetic acid. It is thought that further decarboxylation proceeds and trihalomethane is produced. However, it is difficult to estimate the ability to produce haloacetic acid based on the analysis result of the water to be treated.

The groundwater W to which hypochlorite is added passes through the activated carbon adsorption tower 41 of the activated carbon treatment means 40 in a downward flow, and contacts the activated carbon during this time (activated carbon treatment step).
When hypochlorite is added to groundwater W, trihalomethane may be generated in addition to haloacetic acid. When the groundwater W comes into contact with the activated carbon, the trihalomethane generated in the groundwater W is adsorbed by the activated carbon and removed from the groundwater W. Further, unreacted organic matter and hypochlorite in the groundwater W are also removed from the groundwater W.

The groundwater W that has passed through the activated carbon treatment means 40 is supplied to the ion exchange treatment means 50 through the second water pipe 42. The groundwater W passes through the ion exchanger tower 51 of the ion exchange treatment means 50 in a downward flow, and contacts the anion exchanger during this time (ion exchange treatment step).
When the groundwater W comes into contact with the anion exchanger, the haloacetic acid generated by the addition of hypochlorite is adsorbed on the anion exchanger and removed from the groundwater W. Further, organic substances that could not be removed by the activated carbon treatment means 40 are also removed.

Liquid permeation speed of the ground water W is passed through the ion exchanger column 51 varies depending water, but liquid permeation rate is preferably 200 hr ^-1 or less at a space velocity (SV), more preferably 100 hr ^-1 or less, More preferably, it is 70 hr ⁻¹ or less. Furthermore, liquid passing rate, ^{1hr -1} or preferably at a space velocity (SV), more preferably ^{5 hr -1} or more, more preferably 10 hr ^-1 or more, particularly preferably 20 hr ^-1 or more.
For example, when the amount of the anion exchanger filled in the ion exchanger tower 51 is 100 L or less, the flow rate of the groundwater W is preferably 20 to 200 hr ⁻¹ in terms of space velocity (SV). As the anion exchanger, a strongly basic anion exchanger is suitable. In particular, when the anion exchanger is an anion exchange fiber, the space velocity (SV) is preferably 50 to 1,000 hr ^{−1, and} when the anion exchanger is an anion exchange resin, the space velocity (SV) is 20 to 100 hr ^−1. Is preferred.

  The groundwater W (treated water) that has passed through the ion exchange processing means 50 is supplied to the treated water tank 60 through the third water pipe 53 and temporarily stored. Then, the water is supplied to a water receiving tank (not shown) through the treated water supply pipe 61. When the treated water passes through the third water pipe 53, hypochlorite is added to the treated water at the junction of the third water pipe 53 and the second supply pipe 72.

When continuously treating the groundwater W, it is preferable to periodically regenerate the anion exchanger packed in the ion exchanger tower 51.
When the anion exchanger is regenerated on the spot, the pumping pump 11 is stopped, and then the regenerated water may be supplied to the ion exchanger tower 51.
Further, the ion exchanger column 51 is replaced with a new one filled with an anion exchanger, and the used ion exchanger column 51 is moved to another place, and then the anion exchanger is regenerated. May be.

Examples of the reclaimed water include aqueous solutions of regenerants such as sodium chloride, potassium chloride, sodium sulfate, ammonium sulfate, sodium hydroxide, sodium bromide, sulfuric acid, hydrochloric acid, and seawater. Among these, a sodium chloride aqueous solution and a potassium chloride aqueous solution are preferable because the counter ion of the anion exchanger becomes a chloride ion in one-stage regeneration. When an aqueous solution of a regenerant such as sodium sulfate, sodium hydroxide, sodium bromide or ammonium sulfate is used as the regenerated water, the counter ion of the anion exchanger is sulfate ion, hydroxide ion or bromide ion, so chloride ion In order to convert into a shape, two-stage regeneration may be performed using an aqueous sodium chloride solution or an aqueous potassium chloride solution.
The concentration of the regenerant in the reclaimed water is preferably 2 to 25% by mass, more preferably 2 to 20% by mass, still more preferably 4 to 20% by mass, and particularly preferably 4 to 15% by mass with respect to the total mass of the reclaimed water. .
The amount of regenerated water that flows into the ion exchanger column 51 is preferably in the range where the amount of the regenerant is 50 to 1000 g relative to 1 L of the anion exchanger packed in the ion exchanger column 51. For example, when 500 mL of a 10% strength by weight sodium chloride aqueous solution is passed through the ion exchanger column 51 with respect to 1 L of the anion exchanger, the input amount of the regenerant is 50 g / L-resin, and the regeneration level of the regenerant is 50 g. is called.

In the case where an organic substance is adsorbed on the anion exchanger, a water-soluble alcohol such as methanol or ethanol, an aqueous solution thereof, or an electrolyte solution thereof may be used as a regenerant.
If the function of the anion exchanger does not recover even after regenerative operation, replace the anion exchanger.

"Effect"
According to the water treatment device of the present embodiment described above and the water treatment method using the water treatment device, the water to be treated to which hypochlorite is added and the anion exchanger are brought into contact with each other. The haloacetic acid produced by the addition of chlorite is adsorbed on the anion exchanger and can be removed from the water to be treated.
Since acetic acid is a weak acid, its selectivity to an anion exchanger is low and its adsorption ability is poor, so that an anion exchanger is not suitable for removing acetic acid. For this reason, it is usual from the viewpoint of common general knowledge that an anion exchanger is not suitable for removing haloacetic acid.
However, as a result of intensive studies, the present inventors have surprisingly found that haloacetic acid can be removed by an anion exchanger. The reason why haloacetic acid can be removed by an anion exchanger is not clear, but the acidity of haloacetic acid increases (ie, pKa decreases) due to the electron-withdrawing property of the halogeno group contained in haloacetic acid. It is considered that the haloacetic acid can be easily removed from the water to be treated by being easily adsorbed on the ion exchanger.

  Therefore, conventionally, before adding hypochlorite, organic substances in the water to be treated were removed by pretreatment or ammonia in the water to be treated was decomposed by biological treatment. According to the treatment method and the water treatment apparatus, the haloacetic acid generated in the treatment of the water to be treated can be removed without removing the organic matter and ammonia in the water to be treated by the pretreatment.

  Moreover, in this embodiment, before making the to-be-processed water and the anion exchanger which added hypochlorite contact, to-be-treated water and activated carbon are made to contact. Anion exchangers tend to be deteriorated by hypochlorite, but the activated water can be treated by bringing the water to be treated with hypochlorite into contact with activated carbon before contacting with the anion exchanger. As a result, hypochlorite in the water to be treated is removed. Therefore, deterioration of the anion exchanger due to hypochlorite can be suppressed. Moreover, even if trihalomethane is generated in addition to haloacetic acid by addition of hypochlorite, the trihalomethane can be removed by activated carbon.

"Other forms"
In the water treatment apparatus 1 of the illustrated example, the ion exchange treatment means 50 is provided downstream of the activated carbon treatment means 40, but the ion exchange treatment means 50 and the activated carbon treatment means 40 may be configured as one treatment means. That is, an anion exchanger and activated carbon may be packed in one column. Specifically, in FIG. 1, the anion exchanger may be packed in the activated carbon adsorption tower 41 or the activated carbon may be packed in the ion exchanger tower 51. Such a state is also called a mixed floor. On the other hand, as shown in FIG. 1, the state in which the anion exchanger and the activated carbon are packed in separate towers is also referred to as a single bed. In the case of a mixed bed state of an anion exchanger and activated carbon, the ion exchange treatment step and the activated carbon treatment step are performed simultaneously.

  Further, when the amount of hypochlorite added is small, the activated carbon treatment means 40 is not necessarily installed. However, when trihalomethane is produced by addition of hypochlorite or the anion exchanger is deteriorated by hypochlorite, the activated carbon treatment means 40 is installed upstream of the ion exchange treatment means 50. Alternatively, it is preferable that the ion exchange treatment means 50 and the activated carbon treatment means 40 constitute one treatment means to remove hypochlorite and trihalomethane with activated carbon.

The water treatment apparatus 1 in the illustrated example is a continuous type, but may be a batch type. Moreover, although the anion exchanger is filled in the ion exchanger column 51, for example, a cartridge type container or an FRP cylinder may be filled with the anion exchanger.
Further, in the illustrated water treatment apparatus 1, the other end of the second water conduit 42 is connected to the upper portion of the ion exchanger tower 51, and one end of the third water conduit 53 is connected to the lower portion of the ion exchanger tower 51. Has been. In this case, the groundwater W passes through the ion exchanger tower 51 in a downward flow, but the groundwater W may pass through the ion exchanger tower 51 in an upward flow. In order to pass the groundwater W in an upward flow, for example, the other end of the second water pipe 42 is connected to the lower part of the ion exchanger tower 51 and one end of the third water pipe 53 is connected to the ion exchanger tower 51. Connect to the top of the. Alternatively, the ion exchanger tower 51 may be installed sideways, and the groundwater W may be passed in a sideways flow. However, it is preferable to allow the groundwater W to flow through the ion exchanger tower 51 in a downward flow from the viewpoint of an increase in the adsorption zone length due to the vertical diffusion of the groundwater W, a reduction in the processing amount as a result, and simplification of the process.

Further, as described above, when a sand filtration tower (not shown) is installed upstream of the activated carbon treatment means 40 and the organic matter concentration of the water to be treated is high, polyaluminum chloride (PAC) is added to the water to be treated. It is preferable to add a flocculant such as aluminum sulfate (sulfuric acid band), organic polymer flocculant, and organic flocculant upstream of the sand filtration tower.
If the water to be treated contains a large amount of iron, before treating the water to be treated in the sand filtration tower, air is bubbled or injected into the water to be treated to oxidize iron (II) ions. May be.

Further, a membrane separation means (not shown) may be installed between the ion exchange treatment means 50 and the treated water tank 60. When bacteria, microorganisms or suspended substances are contained in the water to be treated, the bacteria and suspended substances are removed by the membrane separation means.
Although it does not restrict | limit especially as a membrane separation means, The well-known membrane module provided with the well-known separation membrane (filtration membrane) is mentioned. As a kind of separation membrane, a microfiltration membrane (MF membrane), an ultrafiltration membrane (UF membrane), and a reverse osmosis membrane (RO membrane) are preferable.

Furthermore, in the illustrated water treatment apparatus 1, the groundwater W pumped from the well A is once stored in the storage tank 20, but the groundwater W may be directly supplied to the activated carbon treatment means 40. In this case, since the pumping pipe 12 also serves as the first water pipe 21, the first addition means 30 is connected to the pumping pipe 12.
Moreover, when the groundwater W pumped from the well A is temporarily stored in the storage tank 20 as shown in the illustrated example, hypochlorite may be added to the storage tank 20.

  Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.

"Example 1"
As the groundwater, the water quality shown in Table 1 was used. Total organic carbon (TOC) was measured by a combustion oxidation method, pH was measured at a groundwater temperature (generally around 17 ° C.) using a pH meter, and chromaticity was measured by a transmitted light measurement method. .
As water to be treated, groundwater added with trichloroacetic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) so as to have a concentration of 10 ppm was used. This to-be-treated water reproduces the state which added hypochlorite.

As an anion exchanger, 50 mL of a strongly basic anion exchange resin (Mitsubishi Chemical Co., Ltd., “Relite JA810”, porous-like resin) is packed in a column, and groundwater is passed for 1 hour under the condition of a space velocity of SV20hr ^−1. Water and wash the anion exchanger.
After washing, 10 mL of the anion exchanger was weighed with a 10 mL graduated cylinder, dehydrated with a centrifuge, and charged into a 500 mL Erlenmeyer flask. Further, 100 mL of water to be treated was added, and the water to be treated was treated by shaking at room temperature (25 ° C.) for 30 minutes, and then the supernatant was collected.
The collected supernatant was subjected to gas chromatograph (GC) analysis under the following measurement conditions, and the concentration of trichloroacetic acid in the supernatant was measured. The results are shown in Table 2. The lower limit of detection was 1 ppm.

<GC analysis conditions>
GC device: “Agilent 6850 Series” manufactured by Agilent Technologies.
-Temperature rising conditions: 50 ° C to 250 ° C, temperature rising rate 10 ° C / min.
-Analysis time: 20 minutes.
Analytical column: “Agilent J & W GC column HP-5” manufactured by Agilent Technologies.
Carrier gas: He.
-Detector: FID.
Injection volume: 1.00 μL.

"Example 2"
The treated water was treated in the same manner as in Example 1 except that a strongly basic anion exchange resin (“Diaion PA308” manufactured by Mitsubishi Chemical Corporation) was used as the anion exchanger. The concentration of trichloroacetic acid was measured. The results are shown in Table 2.

"Example 3"
As an anion exchanger, 50 mL of a strongly basic anion exchange resin (“Levacite A8071” manufactured by LANXESS) was packed in a glass column having an inner diameter of 13 mm and thoroughly washed with the same ground water as in Example 1.
Subsequently, the to-be-processed water similar to Example 1 was water-flowed on the conditions whose space velocity is SV20hr- ¹ . The treated water was collected after 12 hours and 24 hours from the start of water flow. The collected treated water was subjected to GC analysis in the same manner as in Example 1, and the concentration of trichloroacetic acid in the treated water was measured. The results are shown in Table 2.

After 24 hours had passed since the start of the water supply, the water supply was stopped. Then, a concentration of 10 mass% sodium chloride aqueous solution 150mL space velocity through water under conditions of SV2hr ^-1, further space velocity groundwater is 1 hour through water under conditions of SV5hr ^-1, was regenerated anion exchanger .
After regenerating the anion exchanger, the water to be treated was passed again under the condition that the space velocity was SV20hr ⁻¹ to treat the water to be treated. The treated water was collected after 24 hours from the start of passing the water to be treated, and the concentration of trichloroacetic acid was measured. The results are shown in Table 2.

Example 4
Treated water was treated in the same manner as in Example 1 except that a strongly basic anion exchange resin (“Amberlite IRA458” manufactured by The Dow Chemical Company, Inc.) was used as the anion exchanger. The concentration of trichloroacetic acid in the liquid was measured. The results are shown in Table 2.

"Comparative Example 1"
The treated water was treated in the same manner as in Example 1 except that a strongly acidic cation exchange resin (manufactured by Mitsubishi Chemical Corporation, “Diaion SK1B”) was used instead of the anion exchanger. The concentration of trichloroacetic acid was measured. The results are shown in Table 2.

As is clear from the results in Table 2, in each example, trichloroacetic acid, which is a typical example of haloacetic acid, was not detected from the supernatant or treated water. In particular, in the case of Example 3, trichloroacetic acid was not detected from the treated water even after the anion exchanger was regenerated.
On the other hand, in the case of Comparative Example 1 using a strongly acidic cation exchange resin, the concentration of trichloroacetic acid in the supernatant was 9.8 ppm, and trichloroacetic acid could hardly be removed from the water to be treated.

DESCRIPTION OF SYMBOLS 1 Water treatment apparatus 10 Pumping means 11 Pumping pump 12 Pumping pipe 20 Reservoir 21 First water pipe 30 Adding means (first adding means)
Reference Signs List 31 first storage tank 32 first supply pipe 40 activated carbon treatment means 41 activated carbon adsorption tower 42 second water pipe 50 ion exchange treatment means 51 ion exchanger tower 52 filter 53 third water pipe 60 treated water tank 61 treated water Supply pipe 70 Addition means (second addition means)
71 Second storage tank 72 Second supply pipe A Well W Groundwater

Claims (8)

  A water treatment method for removing haloacetic acid by contacting water to be treated containing haloacetic acid produced by addition of hypochlorite with an anion exchanger. An addition step of adding hypochlorite to the water to be treated;
An ion exchange treatment step in which the treated water to which hypochlorite is added and the anion exchanger are brought into contact with each other;
The water treatment method according to claim 1, comprising: Further comprising an activated carbon treatment step in which the treated water to which the hypochlorite is added is brought into contact with activated carbon;
The water treatment method according to claim 2, wherein the ion exchange treatment step and the activated carbon treatment step are performed simultaneously, or the ion exchange treatment step is performed after the activated carbon treatment step.   The water treatment method according to any one of claims 1 to 3, wherein the water to be treated is groundwater or well water.   The water treatment according to any one of claims 1 to 4, wherein the total amount of organic carbon (TOC) is 1 ppm or more, and water to be treated to which 10 ppm or more of hypochlorite is added is brought into contact with the anion exchanger. Method. A water treatment apparatus for removing haloacetic acid generated when water treatment is performed by adding hypochlorite to water to be treated,
An addition means for adding hypochlorite to the water to be treated;
Ion exchange treatment means for contacting the water to be treated with hypochlorite and the anion exchanger;
A water treatment apparatus comprising: Further comprising activated carbon treatment means for contacting the treated water to which the hypochlorite is added and activated carbon;
The water treatment apparatus according to claim 6, wherein the ion exchange treatment means and the activated carbon treatment means are configured as one treatment means, or the ion exchange treatment means is provided downstream of the activated carbon treatment means.   The water treatment apparatus according to claim 6 or 7, wherein the water to be treated is groundwater or well water.

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