JP6872442B2 - Water treatment method and water treatment equipment - Google Patents

Description

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

In order to make the water to be treated such as groundwater and well water drinkable, it is necessary to remove inorganic ions such as iron and manganese contained in the water to be treated, and organic substances mainly composed of ammonia, humic acid and fulvic acid. ..
The treatment of the water to be treated is usually carried out by adding a 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 produced by the reaction between the organic matter in the water to be treated and the hypochlorite (). For example, see Non-Patent Document 1). In particular, when the concentration of ammonia in the water to be treated is high, the above-mentioned disinfection by-products are produced by the reaction of excess hypochlorite with organic substances in addition to the oxidation of iron, manganese and ammonia and the decomposition of organic substances. The direct reason for this is that it is necessary to add about 10 equivalents or more of hypochlorite for the decomposition of ammonia into nitrogen. Therefore, the amount of hypochlorite added increases, and the amount of disinfection by-products produced also increases. As a result, if a disinfection by-product is produced, it may not be suitable as drinking water. Therefore, it is desirable to remove the disinfection by-product from the water to be treated.

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

Sugino and 3 others, "Production of chloroacetic acids and chloral hydrates in chlorination of fuminic substances in water", Water Pollution Research, 1986, Vol. 9, No. 7, p. 437-444

Japanese Unexamined Patent Publication No. 2005-13883

As described in Patent Document 1, trihalomethane is easily adsorbed on activated carbon and easily removed from the water to be treated.
However, since haloacetic acid is a hydrophilic molecule, it is difficult to be adsorbed on activated carbon, and it is difficult to remove it from water to be treated. Further, 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, a device for accommodating excess activated carbon is required.

So far, there have been few useful means of removing haloacetic acids from the water to be treated.
Therefore, before adding hypochlorite, organic matter in the water to be treated can be removed by adding a coagulant such as polyaluminum chloride or aluminum sulfate or by activated carbon treatment as a pretreatment, or reverse osmosis at the expense of wastewater costs. The amount of disinfection by-products produced was suppressed by desalting with (RO) equipment or by 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 is a water treatment method and water capable of removing haloacetic acids generated in the treatment of water to be treated without removing organic substances and ammonia in the water to be treated by pretreatment. An object of the present invention is 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] It has 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 is added into contact with an anion exchanger [1]. ] The water treatment method described in.
[3] The activated carbon treatment step of bringing the water to be treated to which the hypochlorite is added into contact with the activated carbon is further provided, and the ion exchange treatment step and the activated carbon treatment step are simultaneously performed, or the ion exchange treatment step is performed. The water treatment method according to [2], which is carried out after the activated carbon treatment step.
[4] The water treatment method according to any one of [1] to [3], wherein the water to be treated 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 described in.

[6] A water treatment apparatus for removing haloacetic acids generated when hypochlorite is added to water to be treated and treated with water, and an addition means for adding hypochlorite to water to be treated. A water treatment apparatus comprising an ion exchange treatment means for bringing the water to be treated to which a hypochlorite is added into contact with an anion exchanger.
[7] The activated carbon treatment means for bringing the activated carbon into contact with the water to be treated to which the hypochlorite is added is further provided, 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 water to be treated is groundwater or well water.

According to the water treatment method and the water treatment apparatus of the present invention, the haloacetic acid produced in the treatment of the water to be treated can be removed without removing the organic substances and ammonia in the water to be treated by the 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 drawings below, the scale of each member is appropriately changed in order to make each member recognizable.

The haloacetic acid to be removed in the present invention includes 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. Examples thereof include trihaloacetic acid such as acetic acid and dibromochloroacetic acid and polyhalogenoacetic acid such as salts thereof. Examples of the salt include sodium salt, calcium salt, magnesium salt and the like.
Haloacetic acids tend to increase in proportion to the product of the amount of hypochlorite added to the water to be treated and the content of organic substances in the water to be treated. Among organic substances, especially when the content of humic acid having a phenol skeleton is high, disinfection by-products tend to increase, but the mechanism of haloacetic acid production has not been clarified.

Examples of the water to be treated to be treated by the present invention include groundwater, well water, leachate, river water, lake water and the like. In particular, when treating groundwater or well water with water, the amount of hypochlorite added is larger than when treating river water with water, so disinfection by-products such as haloacetic acids tend to be easily 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 the water to be treated is groundwater.

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

The pumping means 10 pumps groundwater W as water to be treated from the well A, and includes a pump 11 for pumping groundwater W and a pumping pipe 12.
One end of the pumping pipe 12 of 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 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 adding means 30 (first adding means 30) for adding hypochlorite to the groundwater W is connected to the first water pipe 21.
The first addition means 30 includes a first storage tank 31 for storing hypochlorite and a first supply pipe 32 for supplying 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 oxidizing agent, and flowability.

The activated carbon treatment means 40 brings the groundwater W to which hypochlorite is added into contact with the activated carbon.
The activated carbon treatment means 40 of the present 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 brings the groundwater W to which hypochlorite is added into contact with the anion exchanger.
The ion exchange processing means 50 of the present embodiment includes an ion exchanger tower 51 filled with an anion exchanger. A filter 52 for preventing the outflow of the anion exchanger is installed in the ion exchanger tower 51.
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 pipe 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 tower 51 is filled with an anion exchanger so as to form a fixed bed or a fluidized bed.
The anion exchanger has an ion exchanger (fixed ion) chemically bonded to the skeletal polymer on the surface and inside of the skeletal polymer (resin matrix). Haloacetic acids and organic substances in the groundwater W are adsorbed by this ion exchange group, and haloacetic acids and organic substances can be removed from the groundwater W.
Examples of the skeleton polymer include styrene-based, (meth) acrylic-based, (meth) acrylamide-based, and cellulose-based polymers. Among these, (meth) acrylic and (meth) acrylamide polymers, which are hydrophilic polymers, are preferable from the viewpoint of organic contamination resistance, and styrene polymers are preferable from the viewpoint of cost.

The anion exchanger may be weakly basic or strongly basic, but a strongly basic anion exchanger is preferable because haloacetic acid and organic substances are easily adsorbed.
Here, the "strongly basic anion exchanger" is an anion exchanger having a quaternary ammonium group which is in a dissociated state even if it is alkaline as an ion exchange group.

Examples of the strong 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 due to elution due to inferior thermal stability of ion exchange groups, generation of odor derived from ion exchange groups, and ion exchange groups due to long-term use A trimethylammonium group is preferable as the ion exchange group from the viewpoint of generation of formaldehyde due to the loss of the ion exchange group and the decomposition of the ion exchange group.

Examples of the anion exchanger include anion exchange resin and anion exchange fiber.
The particle size of the anion exchange resin is preferably large from the viewpoint of suppressing an increase in the pressure loss of the resin. The average particle size 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 once-through exchange capacity, it is preferable that the particle size of the anion exchange resin is small. The average particle size 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 having the same particle size.
When a strong basic anion exchange resin is used as the anion exchange resin, the strong basic anion exchange resin may be type I or type II.

Commercially available products can be used as the anion exchange resin, for example, Amberlite "IRA402", "IRA901", "XT5007", "IRA958", "IRA938", "IRA458" manufactured by The Dow Chemical Company, and the like. Dowex Marathon "A", "SBR", "MSA", "MSA-1", "C", "C-1"; Lanxess Rebatit "MP500", "M500", "MP504", "A8071" "Indion A930" manufactured by Ion Exchange India; "Zhengguang ZGD730" manufactured by Hangzhou Zhengguang Resin Co., Ltd .; Diamond "SA10A", "SA12A", "PA308" manufactured by Mitsubishi Chemical Co., Ltd., and Rewrite "JA800", "JA810" and the like are suitable.

The fibers constituting the anion exchange fibers may be short fibers or long fibers. 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 fibers 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.
Commercially available products can be used as the anion exchange fiber, and for example, "IEF-SA" manufactured by Nichibi Co., Ltd. is suitable.

The 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 pipe 53, and is stored in the treatment 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 treatment water tank 60.
A treated water supply pipe 61 for supplying to a water receiving tank (not shown) is connected to the treated water tank 60.

An addition means 70 (second addition means 70) for adding hypochlorite to the groundwater 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 for storing hypochlorite, and a second supply pipe 72 for supplying 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.

When the groundwater W contains iron or manganese, a sand filtration tower (not shown) filled with sand such as filtered sand, filtered gravel, manganese sand, and manganese dioxide grains is installed upstream of the activated charcoal treatment means 40. It is desirable to do.

"Water treatment method"
Hereinafter, an example of a water treatment method for groundwater using the water treatment device 1 shown in FIG. 1 will be described.
First, the pump 11 is operated to pump the groundwater W from the well A. The pumped groundwater W 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 confluence of the first water pipe 21 and the first supply pipe 32 (addition step). .. If the groundwater W contains iron or manganese, if a sand filtration tower (not shown) is installed upstream of the activated carbon treatment means 40, the iron oxidized and precipitated by hypochlorite will be filtered. To. Further, if the sand filtration tower is filled with manganese sand, manganese is removed by catalytic oxidation with the manganese sand.
The required amount of hypochlorite added depends on the concentrations of iron, manganese, ammonia, and organic matter in the groundwater W. In particular, the influence of ammonia concentration is large, 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 viewpoint of by-product of haloacetic acid and economic efficiency.
When the total organic carbon (TOC) of the groundwater W is 1 ppm or more and the amount of hypochlorite added is 10 ppm or more with respect to 1 L of the groundwater W, haloacetic acids and trihalomethanes tend to be easily produced. 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 mechanism of haloacetic acid formation has not been clarified, the phenolic skeleton components in humic acid and fulvic acid are chlorinated radically oxidized to produce haloacetic acids. It is thought that the decarboxylation reaction proceeds further and trihalomethane is produced. However, it is difficult to estimate the ability to produce haloacetic acid based on the analysis results of the water to be treated.

The groundwater W to which the hypochlorite is added passes through the activated carbon adsorption tower 41 of the activated carbon treatment means 40 in a downward flow, and comes into contact with the activated carbon during this period (activated carbon treatment step).
When hypochlorite is added to groundwater W, trihalomethane may be produced in addition to haloacetic acid. When the groundwater W comes into contact with the activated carbon, the trihalomethanes generated in the groundwater W are adsorbed on the activated carbon and removed from the groundwater W. In addition, 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 in the meantime, comes into contact with the anion exchanger (ion exchange treatment step).
When the groundwater W comes into contact with the anion exchanger, the haloacetic acid produced by the addition of hypochlorite is adsorbed on the anion exchanger and removed from the groundwater W. In addition, organic substances that could not be completely 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.
Further, for example, when the filling amount of the anion exchanger into the ion exchanger tower 51 is 100 L or less, the liquid passing rate of the groundwater W ^{is preferably 20 to 200 hr -1} in terms of space velocity (SV), and is used at this time. As the anion exchanger to be used, a strongly basic anion exchanger is suitable. In particular, when the anion exchange body is an anion exchange fiber, the space velocity (SV) ^{is preferably 50 to 1,000 hr -1, and} when the anion exchange resin is used, the space velocity (SV) is 20 to 100 hr ^-1. Is preferable.

The groundwater W (treated water) that has passed through the ion exchange treatment means 50 is supplied to the treated water tank 60 through the third water pipe 53 and temporarily stored. Then, it is supplied to the 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 confluence of the third water pipe 53 and the second supply pipe 72.

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

Examples of the regenerated water include aqueous solutions of regenerating agents such as sodium chloride, potassium chloride, sodium sulfate, ammonium sulfate, sodium hydroxide, sodium bromide, sulfuric acid, hydrochloric acid, and seawater. Among these, sodium chloride aqueous solution and potassium chloride aqueous solution are preferable because the counter ion of the anion exchanger becomes chloride ion in the one-stage regeneration. When an aqueous solution of a regenerating agent such as sodium sulfate, sodium hydroxide, sodium bromide, or ammonium sulfate is used as the regenerated water, the pair ion of the anion exchanger becomes sulfate ion, hydroxide ion, or bromide ion, and thus chloride ion. In order to convert it into a form, it may be regenerated in two stages using an aqueous solution of sodium chloride or an aqueous solution of potassium chloride.
The concentration of the reclaiming agent in the reclaimed water is preferably 2 to 25% by mass, more preferably 2 to 20% by mass, further 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 reclaimed water flowing through the ion exchanger tower 51 is preferably in the range of 50 to 1000 g with respect to 1 L of the anion exchanger filled in the ion exchanger tower 51. For example, when 500 mL of a sodium chloride aqueous solution having a concentration of 10% by mass with respect to 1 L of the anion exchanger is passed through the ion exchanger tower 51, the amount of the regenerating agent added is 50 g / L-resin, and the regeneration level of the regenerating agent is 50 g. It is called.

When 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 the regenerating agent.
If the function of the anion exchanger does not recover even after the regeneration operation, replace the anion exchanger.

"Action effect"
According to the water treatment apparatus of the present embodiment described above and the water treatment method using the water treatment apparatus, the water to be treated to which the hypochlorite is added is brought into contact with the anion exchanger to be described as follows. The haloacetic acid produced by the addition of hypochlorite is adsorbed on the anion exchanger, and the haloacetic acid can be removed from the water to be treated.
Since acetic acid is a weak acid, its selectivity for an anion exchanger is low and its adsorptive capacity is inferior. Therefore, it is said that an anion exchanger is not suitable for removing acetic acid. Therefore, it is usual from the viewpoint of common general knowledge that the anion exchanger is not suitable for removing haloacetic acid.
However, as a result of diligent studies, the present inventors have surprisingly found that haloacetic acid can be removed by an anion exchanger. The reason why haloacetic acids can be removed by an anion exchanger is not clear, but the electron-withdrawing property of halogeno groups contained in haloacetic acid increases the acidity of haloacetic acid (that is, reduces pKa), resulting in an anion. It is considered that haloacetic acid can be removed from the water to be treated because it is easily adsorbed on the ion exchanger.

Therefore, conventionally, before adding hypochlorite, organic substances in the water to be treated are removed by pretreatment, and ammonia in the water to be treated is decomposed by biological treatment. However, the water of the present invention has been used. According to the treatment method and the water treatment apparatus, the haloacetic acid produced in the treatment of the water to be treated can be removed without removing the organic substances and ammonia in the water to be treated by the pretreatment.

Further, in the present embodiment, the water to be treated and the activated carbon are brought into contact with each other before the water to be treated to which the hypochlorite is added is brought into contact with the anion exchanger. The anion exchanger tends to be deteriorated by hypochlorite, but by bringing the water to be treated with hypochlorite into contact with the activated charcoal before contacting it with the anion exchanger, the activated charcoal is used. Removes hypochlorite in the water to be treated. Therefore, deterioration of the anion exchanger due to hypochlorite can be suppressed. Moreover, even if trihalomethane is produced in addition to haloacetic acid by the addition of hypochlorite, 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 tower. Specifically, in FIG. 1, the anion exchanger may be filled in the activated carbon adsorption tower 41, or the activated carbon may be filled 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 filled in separate towers is also referred to as a single bed. In the case of a mixed bed state of the anion exchanger and activated carbon, the ion exchange treatment step and the activated carbon treatment step are performed at the same time.

Further, when the amount of hypochlorite added is small, it is not always necessary to install the activated carbon treatment means 40. However, if trihalomethane is generated by the 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 one treatment means is composed of the ion exchange treatment means 50 and the activated charcoal treatment means 40, and hypochlorite and trihalomethane are removed by the activated charcoal.

The water treatment device 1 in the illustrated example is a continuous type, but may be a batch type. Further, although the anion exchanger is filled in the ion exchanger tower 51, for example, a cartridge type container or an FRP cylinder may be filled with the anion exchanger.
Further, in the water treatment device 1 of the illustrated example, the other end of the second water pipe 42 is connected to the upper part of the ion exchanger tower 51, and one end of the third water pipe 53 is connected to the lower part of the ion exchanger tower 51. Has been done. 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 allow the groundwater W to pass upward, 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. Just connect to the top of. Further, the ion exchanger tower 51 may be installed sideways and the groundwater W may be passed in a lateral flow. However, from the viewpoint of increasing the adsorption zone length due to the longitudinal diffusion of the groundwater W, reducing the processing amount as a result, and simplifying the process, it is preferable to allow the groundwater W to pass through the ion exchanger tower 51 in a downward flow.

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. , Aluminum sulfate (aluminum band), organic polymer coagulant, organic coagulant and other coagulants are preferably added upstream of the sand filtration tower.
If the water to be treated contains a large amount of iron, air is bubbled or press-fitted into the water to be treated to air-oxidize iron (II) ions before the water to be treated is treated by the sand filtration tower. You may.

Further, a membrane separation means (not shown) may be installed between the ion exchange treatment means 50 and the treatment water tank 60. If the water to be treated contains bacteria, microorganisms or suspended solids, the membrane separation means removes the bacteria and suspended solids.
The membrane separation means is not particularly limited, and examples thereof include a known membrane module provided with a known separation membrane (filtration membrane). As the type of separation membrane, a microfiltration membrane (MF membrane), an ultrafiltration membrane (UF membrane), and a reverse osmosis membrane (RO membrane) are preferable.

Further, in the water treatment device 1 of the illustrated example, the groundwater W pumped from the well A is temporarily 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 passage pipe 21, the first adding means 30 is connected to the pumping pipe 12.
Further, 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 with reference to Examples, but the present invention is not limited thereto.

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

As an anion exchanger, 50 mL of a strongly basic anion exchange resin (manufactured by Mitsubishi Chemical Co., Ltd., "Relite JA810", porous resin) is filled in a column, and groundwater is passed through for 1 hour under the condition of a ^{space velocity of SV20hr-1.} Water was added and the anion exchanger was washed.
After washing, 10 mL of the anion exchanger was weighed with a 10 mL graduated cylinder, dehydrated with a centrifuge, and then placed in a 500 mL Erlenmeyer flask. Further, 100 mL of water to be treated was added, and the mixture was shaken at room temperature (25 ° C.) for 30 minutes to treat the water to be treated, and then the supernatant was collected.
The collected supernatant was analyzed by gas chromatography (GC) 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.
-Rising conditions: 50 ° C to 250 ° C, heating 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 amount: 1.00 μL.

"Example 2"
The water to be treated was treated in the same manner as in Example 1 except that a strong basic anion exchange resin (manufactured by Mitsubishi Chemical Co., Ltd., “Diaion PA308”) was used as the anion exchanger, and the solution was added to the supernatant. The concentration of trichloroacetic acid was measured. The results are shown in Table 2.

"Example 3"
As an anion exchanger, 50 mL of a strong basic anion exchange resin (“Lexess A8071” manufactured by LANXESS) was filled in a glass column having an inner diameter of 13 mm, and thoroughly washed with the same groundwater as in Example 1.
Next, the same water to be treated as in Example 1 was passed under ^{the condition of a space velocity of SV20hr-1} , and the water to be treated was treated. The treated water was collected 12 hours and 24 hours after the start of the flow of the water to be treated. 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 from the start of the flow of the water to be treated, the flow of the water to be treated was stopped. Next, 150 mL of a sodium chloride aqueous solution having a concentration of 10% by mass was passed under ^{the condition of a space velocity of SV2hr -1} , and groundwater was further passed under ^{the condition of a space velocity of SV5hr-1} for 1 hour to regenerate the anion exchanger. ..
After the anion exchanger was regenerated, the water to be treated was ^{passed again under the condition that the space velocity was SV20hr-1} , and the water to be treated was treated. The treated water was collected 24 hours after the start of water flow to be treated, and the concentration of trichloroacetic acid was measured. The results are shown in Table 2.

"Example 4"
The water to be treated was treated in the same manner as in Example 1 except that a strong basic anion exchange resin (manufactured by The Dow Chemical Company, "Amberlite IRA458") was used as the anion exchanger, and the supernatant was obtained. The concentration of trichloroacetic acid in the liquid was measured. The results are shown in Table 2.

"Comparative Example 1"
The water to be treated was treated in the same manner as in Example 1 except that a strongly acidic cation exchange resin (manufactured by Mitsubishi Chemical Co., Ltd., “Diaion SK1B”) was used instead of the anion exchanger, and the solution was added to the supernatant. 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 known as a representative example of haloacetic acid, was not detected in the supernatant or treated water. In particular, in the case of Example 3, trichloroacetic acid was not detected in the treated water even after the anion exchanger was regenerated.
On the other hand, in the case of Comparative Example 1 using the 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.

1 Water treatment device 10 Water pumping means 11 Pumping pump 12 Pumping pipe 20 Storage tank 21 First water pipe 30 Addition means (first addition means)
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 exchange 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 in which water to be treated containing haloacetic acid produced by the addition of hypochlorite is brought into contact with an anion exchanger to remove haloacetic acid. The addition process of adding hypochlorite to the water to be treated, and
An ion exchange treatment step in which the water to be treated to which hypochlorite is added is brought into contact with the anion exchanger,
The water treatment method according to claim 1. It further has an activated carbon treatment step in which the water to be treated to which the hypochlorite is added is brought into contact with the activated carbon.
The water treatment method according to claim 2, wherein the ion exchange treatment step and the activated carbon treatment step are carried out at the same time, or the ion exchange treatment step is carried out 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 water to be treated, which has a total organic carbon (TOC) of 1 ppm or more and is added with hypochlorite of 10 ppm or more, is brought into contact with the anion exchanger. Method. A water treatment device that removes haloacetic acid generated during water treatment by adding hypochlorite to the water to be treated.
Addition means for adding hypochlorite to the water to be treated,
An ion exchange treatment means for bringing the water to be treated to which hypochlorite is added into contact with the anion exchanger,
A water treatment device. An activated carbon treatment means for bringing the water to be treated to which the hypochlorite is added into contact with the activated carbon is further provided.
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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