JP2012223700A - Method and apparatus for removing dissolved aluminum - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for removing dissolved aluminum from water to be processed containing bicarbonate ions (HCO-) with a high removal rate, by which the decrease of the removal rate and the pH at the initial stage of passing water are suppressed.SOLUTION: Water to be processed is caused to pass through an ion exchange resin layer comprising a mixed bed of a salt-type strongly acidic cation exchange resin of an alkali metal or an alkaline earth metal, and Cl (chlorine)-type strongly basic anion exchange resin. For instance, Na (sodium)-type strongly acidic cation resin is used as the salt-type strongly acidic cation exchange resin.

Description

The present invention relates to a method and apparatus for removing dissolved aluminum (Al) from water to be treated containing bicarbonate ions (HCO ₃ ⁻ ) to reduce the amount of dissolved aluminum.

  Coagulation sedimentation filtration methods and coagulation filtration methods are widely used as treatment methods when producing suspended water such as tap water and drinking water by removing suspended substances from water containing suspended substances such as river water and lake water. As the aggregating agent at that time, an aluminum-based aggregating agent such as polyaluminum chloride (PAC) is often used.

  Most of the aluminum flocculant added to flocculate and remove suspended solids is removed along with the suspended solids by precipitation or filtration, but some remains undissolved in the water after the suspended solids have been removed. The reaction remains and is detected as a trace amount of aluminum.

  In tap water, drinking water, and the like, a limit is set for the amount of remaining aluminum from the viewpoint of color. With regard to the aluminum content, in the tap water quality standard, 0.2 mg / L is defined as the standard value, and 0.1 mg / L is defined as the water quality management target value. In the food industry and the like, there is a demand for further reducing the remaining amount of aluminum.

  Aluminum derived from the flocculant is considered to exist mainly as a dissolved species in water. Non-Patent Document 1 discloses that by using a Cl-type strongly basic anion exchange resin, aluminum in the water to be treated, that is, water to be treated is adsorbed on the anion exchange resin, and the amount of aluminum in the water is reduced. is doing.

  In the method for reducing the amount of dissolved aluminum contained in the water to be treated by using a Cl-type strongly basic anion exchange resin, it must be considered that bicarbonate ions are contained in the water to be treated.

When tap water or drinking water is used as water to be treated, the water to be treated is derived from carbon dioxide (CO ₂ ) in the air and generally contains bicarbonate ions. When water to be treated containing bicarbonate ions is passed through a Cl-type strongly basic anion exchange resin, at the initial stage of water passage, ions of bicarbonate ions and Cl (chlorine) bonded to the functional groups of the anion exchange resin. An exchange reaction takes place, and bicarbonate ions in the water to be treated are removed, thereby lowering the pH (hydrogen ion index) in the treated water, that is, the treated water. The equilibrium formula of bicarbonate ion in water is
^{_{HCO 3 - + H + ⇔ H}} 2 CO 3
It is expressed. Considering the acid dissociation constant in this equilibrium, if the pH of the water to be treated is approximately 4.8 or higher, bicarbonate ions will be present in the water to be treated.

  Keeping in mind that the water to be treated is water from which suspended substances have been removed in order to obtain, for example, tap water or drinking water, the pH of the water to be treated is often around 7. When treated water is passed through a Cl-type strongly basic anion exchange resin, the pH of the water obtained at the initial stage of passing water is about 5.

  By the way, aluminum is an amphoteric metal, and its dissolved state is said to have a high anion ratio on the alkali side and a high cation ratio on the acid side, at a pH of around 6.5. When bicarbonate ions in the water to be treated are removed and the pH is lowered, the proportion of dissolved aluminum in the form of a cation increases, and the removal rate of aluminum by the Cl-type strongly basic anion exchange resin decreases. In addition, a decrease in pH in treated water not only leads to a deviation from the water quality standard (pH 5.8 to 8.6) from the viewpoint of applications such as tap water and drinking water, but also leads to an increase in corrosivity, It is not preferable.

Maria Pesavento, et al., "Investigation of the speciation of aluminum in drinking waters by sorpition on a strong anionic-exchange resin AG1X8," Analytica Chimica Acta, 367 (1998), 215-222

  As a method of removing aluminum from the water to be treated, in the method of passing the water to be treated through a Cl-type strongly basic anion exchange resin, the pH is lowered in the water obtained at the initial stage of the water flow, and thereby the aluminum by the anion exchange resin. This causes a problem that the removal rate of the water is reduced, and further, the pH value deviates from the standard, which causes corrosion of the piping and the like.

  An object of the present invention is an aluminum removal method and apparatus that can remove dissolved aluminum in water to be treated containing bicarbonate ions at a high removal rate, and a reduction in the removal rate and a pH in the initial stage of water flow are suppressed. It is to provide a method and apparatus.

  The method for removing aluminum of the present invention is a method for removing aluminum from water to be treated, wherein a salt-type strongly acidic cation exchange resin of an alkali metal or alkaline earth metal and a Cl-type strongly basic anion exchange resin are mixed. Water to be treated is allowed to flow through the ion exchange resin layer.

  The aluminum removing apparatus of the present invention is an aluminum removing apparatus that removes aluminum from water to be treated, and is a mixed bed of an alkali metal or alkaline earth metal salt-type strongly acidic cation exchange resin and a Cl-type strongly basic anion exchange resin. It has an ion exchange device through which water to be treated is passed.

When water to be treated containing bicarbonate ions is passed through a Cl-type strongly basic anion exchange resin, as described above, bicarbonate ions are removed by an ion exchange reaction at the initial stage of passing water. It has the effect of increasing the hydrogen ion concentration in the water and lowering the pH of the treated water. In the present invention, a salt-type strongly acidic cation exchange resin of an alkali metal or alkaline earth metal is further mixed with a Cl-type strongly basic anion exchange resin to form a mixed bed. This time, the hydrogen ions released into the water cause an ion exchange reaction with a cation (for example, Na ⁺ ) bonded to the functional group of the salt-type strongly acidic cation exchange resin. As a result, the hydrogen ion concentration in water does not increase, and a decrease in the pH of the treated water is suppressed. Since the Cl-type strongly basic anion exchange resin efficiently captures the aluminum anion by suppressing the pH decrease, the decrease in the aluminum removal rate is suppressed. Even if some aluminum ions are dissolved as cations, the aluminum cations are removed by the salt-type strongly acidic cation exchange resin.

  In the present invention, the pH of the water to be treated is, for example, 4.8 or more so that bicarbonate ions can exist. In particular, when the use of the water to be treated is tap water or drinking water, the pH of the water to be treated is, for example, in the range of 5.8 to 8.6 defined in the tap water quality standard.

  In the present invention, as the salt-type strongly acidic cation exchange resin, for example, a strongly acidic cation exchange resin of Na (sodium) form, K (potassium) form, Mg (magnesium) form, or Ca (calcium) form can be used. . In particular, Na-type strongly acidic cation exchange resin can be preferably used.

  According to the present invention, an ion exchange resin layer comprising an alkali metal or alkaline earth metal salt-type strongly acidic cation resin and a Cl-type strongly basic anion exchange resin as a mixed bed is used. Dissolving aluminum in the water to be treated containing bicarbonate ions while suppressing the decrease in pH at the initial stage of water flow, as will be apparent from Examples and the like described later, by allowing the water to be treated to flow. Can be stably removed.

It is a figure which shows the structure of the aluminum removal apparatus of principle embodiment of this invention. It is a figure which shows the structure of the aluminum removal apparatus of another embodiment of this invention. 3 is a graph showing changes in pH of treated water in Example 1 with time. It is a graph which shows the time change of the pH of the treated water in the comparative example 1. It is a graph which shows the change of pH according to the water flow time in Example 2. FIG. It is a graph which shows the change of pH according to the amount of water flow per anion resin in Example 2.

  FIG. 1 shows an aluminum removal apparatus in a principle embodiment of the present invention. This aluminum removing apparatus includes a raw water tank 1 for storing water to be aluminum removed, that is, treated water, an ion exchange device 2, a pump 3 for supplying treated water from the raw water tank 1 to the ion exchange device 2, and The treated water, that is, the treated water flows out from the ion exchange device 2. An ion exchange resin layer 4 in which an alkali metal or alkaline earth metal salt-type strongly acidic cation exchange resin and a Cl-type strongly basic anion exchange resin are mixed is provided inside the ion exchange apparatus 2. The treated water supplied to the ion exchange device 2 by the pump 3 passes through the ion exchange resin layer 4.

  For example, the water to be treated is water from which suspended substances have been removed by coagulating and filtering the suspended substances with an aluminum-based flocculant. For example, the water to be treated is water used as tap water or drinking water. The water to be treated contains bicarbonate ions due to the fact that carbon dioxide in the air is dissolved. The pH of the water to be treated is, for example, from 5.8 to 8.6 as defined in the water quality standards.

  The salt-type strongly acidic cation exchange resin uses an alkali metal or an alkaline earth metal as an ionic form such as Na-type, K-type, Mg-type, and Ca-type. The ionic form of the salt-type strongly acidic cation exchange resin may be an ionic form of an ion with a selectivity factor that is not too high. The Na form is most suitable because it has a small difference in selectivity with respect to aluminum ions and a large difference in selectivity with aluminum ions.

  Although it is not unimaginable to use other halogen-type strongly basic anion exchange resins instead of Cl-type strongly basic anion exchange resins, considering the factors such as selectivity and toxicity, Cl-type strong basicity It is most preferable and practical to use an anion exchange resin.

  Next, the ratio of the salt-type strongly acidic cation exchange resin and the Cl-type strongly basic anion exchange resin in the ion-exchange resin layer 4 in which the salt-type strongly acidic cation exchange resin and the Cl-type strongly basic anion exchange resin are mixed. explain. When the mixing ratio of the salt-type strongly acidic cation exchange resin such as Na-type is too small, the effect of suppressing the decrease in pH is not exhibited. On the other hand, when the mixing ratio of the salt-type strongly acidic cation exchange resin is too large, it is considered that the removal of aluminum is mainly performed by the Cl-type strongly basic anion exchange resin. Therefore, the ion exchange resin layer 4 In this case, the yield of treated water until aluminum breaks is too low. Therefore, in terms of volume, with respect to the salt-type strongly acidic cation exchange resin 1, the Cl-type strongly basic anion exchange resin is preferably 1 or more and 5 or less, and more preferably 1 or more and 3 or less.

  In the aluminum removing apparatus shown in FIG. 1, when the water to be treated containing bicarbonate ions is supplied from the raw water tank 1 to the ion exchange device 2 by the pump 3, the initial stage of water flow to the ion exchange resin layer 4. , The bicarbonate ions are removed from the water to be treated by the ion exchange reaction in the Cl-type strongly basic anion exchange resin, and as a result, the hydrogen ion concentration in the water increases due to the dissociation equilibrium of the bicarbonate ions. The hydrogen ions cause an ion exchange reaction with the salt-type strongly acidic cation exchange resin mixed in the ion exchange resin layer 4 and are fixed to the cation exchange resin. Dissolved aluminum in the water to be treated is removed mainly by an ion exchange reaction with a Cl-type strongly basic anion exchange resin. When dissolved aluminum in the form of a cation is present, the dissolved aluminum is removed by an ion exchange reaction with a salt-type strongly acidic cation exchange resin.

  Therefore, the aluminum removing apparatus shown in FIG. 1 can stably remove dissolved aluminum in the water to be treated containing bicarbonate ions while suppressing a decrease in pH at the initial stage of water flow.

  FIG. 2 shows an aluminum removing apparatus according to another embodiment of the present invention. The aluminum removing apparatus shown in FIG. 2 removes dissolved aluminum from the water to be treated containing bicarbonate ions, and further has a function of regenerating an ion exchange resin layer in a mixed bed.

  The aluminum removing apparatus shown in FIG. 2 is roughly classified into an ion exchange apparatus 10, a raw water tank 12 for storing the water to be treated, and a regenerant for storing a regenerant such as sodium chloride (NaCl) water and hydrochloric acid used for regeneration. A storage tank 14 and a treated water tank 16 for storing treated water that has flowed out of the ion exchange device 10 and from which aluminum has been removed are provided, and various pumps, piping, and valves are provided. The ion exchange apparatus 10 is configured as a resin-filled tower that holds an ion exchange resin layer 30 in which a Na-type strongly acidic cation exchange resin and a Cl-type strongly basic anion exchange resin are mixed, and further includes an ion exchange resin. A collector 24 is provided for use in reproducing the layer 30.

  A pump 22a for supplying water to be treated is provided at the outlet of the raw water tank 12, the outlet of the pump 22a is connected to the top of the ion exchange device 10 by a pipe 20a, and a valve 21a is provided in the pipe 20a. ing. The bottom of the ion exchange device 10 and the treated water tank 16 are connected by a pipe 20b, and a valve 21b is provided in the pipe 20b. A pump 22b for supplying a regenerant is provided at the outlet of the regenerant reservoir 14, and the outlet of the pump 22b is connected to the pipes 20a and 20b by pipes 20c and 20d, respectively. 21c and 21d are provided. A pump 22c is also provided at the outlet of the treated water tank 16, and the outlet of the pump 22c is connected to the pipe 20b via the pipe 20e. A pipe 20f for introducing air is connected to the pipe 20b. Valves 21e and 21f are provided on the pipes 20e and 20f, respectively. A pipe 20g for draining and exhausting at the time of backwashing and a pipe 20i for intake are connected to the top of the ion exchange device 10, and valves 21g and 21i are provided on the pipes 20g and 20i, respectively. . The collector 24 of the ion exchange apparatus 10 is connected with a pipe 20h for the regenerated waste liquid, and the pipe 20h is provided with a valve 21h. A pipe 20j for drain is connected to the pipe 20b, and a valve 21j is provided in the pipe 20j.

  Next, the operation of the aluminum removing apparatus shown in FIG. 2 will be described. In this aluminum removing apparatus, a treated water production process for removing aluminum in the water to be treated by ion exchange by the ion exchange apparatus 10, a separation process for separating the ion exchange resin layer 30 of the mixed bed in the ion exchange apparatus 10 into each resin, These steps are repeated with one cycle consisting of the regeneration step of regenerating the separated Na-type strongly acidic cation exchange resin and Cl-type strongly basic anion exchange resin and the mixing step of mixing the regenerated resins. Hereinafter, each step will be described.

<Processed water production process>
The pump 22a is operated, the valves 21a and 21b are opened, and the water to be treated in the raw water tank 12 is fed into the ion exchange device 10. The water to be treated is ion-exchanged as described above by the Na-type strongly acidic cation exchange resin and the Cl-type strongly basic anion exchange resin in the mixed bed in the ion exchange apparatus 10 to remove dissolved aluminum in the water to be treated. The The treated water from which aluminum has been removed is stored in the treated water tank 16 via the pipe 20b.

<Separation process>
In the aluminum removing apparatus shown in FIG. 2, after the aluminum removing process by ion exchange was performed for a predetermined time, the valves 21a and 21b were closed, the pump 22c was operated, the valves 21e and 20g were opened, and the aluminum removing process was performed. The treated water is fed as backwash water from the pipe 20e into the ion exchange apparatus 10, the ion exchange resin layer 30 in the ion exchange apparatus 10 is backwashed by upward flow, and the backwash water is discharged from the pipe 20g to the outside of the system. Discharge. By such backwashing, the ion exchange resin layer 30 in the mixed bed flows while standing up to a predetermined height in the ion exchange apparatus 10 configured as a resin packed tower, and due to the difference in specific gravity between the two resins, Na type strong acidity The cation exchange resin and the Cl-type strongly basic anion exchange resin are separated. In general, the specific gravity of the cation exchange resin is larger than that of the anion exchange resin. Therefore, when left standing, a layer of Na-type strongly acidic cation exchange resin is formed downward from the position of the collector 24, and Cl form is formed upward from the position of the collector 24. A layer of strongly basic anion exchange resin is formed.

<Regeneration process>
By closing the valves 21e and 21g, operating the pump 22b and opening the valve 21c, the regenerant is fed into the ion exchange device 10 through the pipes 20c and 20a. The regenerant comes into contact with the upper-layer Cl-type strongly basic anion exchange resin, the Cl-type strongly basic anion exchange resin is regenerated, and the regenerated waste liquid is discharged out of the system from the collector 24 through the pipe 20h. . Further, the valve 21d is opened, the pump 22b is operated, and the regenerant is fed into the ion exchange device 10 through the pipes 20d and 20b. The regenerant comes into contact with the lower Na-type strongly acidic cation exchange resin to regenerate the Na-type strongly acidic cation exchange resin, and the regeneration treatment waste liquid is discharged out of the system from the collector 24 through the pipe 20h. In addition, in order to prevent precipitation of calcium sulfate or calcium carbonate, it is better that the regenerant is fed separately for the Na-type strongly acidic cation exchange resin and the Cl-type strongly basic anion exchange resin. However, if there is no risk of precipitation of calcium sulfate or calcium carbonate even if both resins are regenerated at the same time due to the quality of the water to be treated, the separation step is omitted and the collector 24 is installed at the bottom of the ion exchanger 10. In addition, the regeneration treatment of both resins may be performed with only one regenerant feeding liquid and in a mixed bed.

<Mixing process>
In the aluminum removing apparatus of the present invention, the Na-type strongly acidic cation exchange resin and the Cl-type strongly basic anion exchange resin are used as a mixed bed. Therefore, when the above-described separation step is performed, both resins are mixed by the mixing step. Then, the mixed-bed ion exchange resin layer 30 must be formed again. In the mixing step, the valves 21c and 21d are closed, the valves 21i and 21j are opened, and the water level in the ion exchange device 10 is adjusted (for example, the upper surface of the ion exchange resin layer 30 +10 cm). Next, the valves 21f and 21g are opened, and air is introduced into the ion exchange resin layer 10 through the pipes 20f and 20b. Air is supplied by installing an air compressor or the like in the pipe 20f. The air introduced into the ion exchange device 10 mixes the separated Na-type strongly acidic cation exchange resin and Cl-type strongly basic anion exchange resin to form a mixed bed ion exchange resin layer 30. Then, the above-mentioned process water manufacturing process is performed again.

  The aluminum removal apparatus of each embodiment described above can be used to remove dissolved aluminum in the water to be treated to generate water used for, for example, the food industry. For example, a reverse osmosis membrane (RO membrane) ) Can be used for pretreatment of water to be treated. The ion exchange resin layer in the aluminum removal device can also remove aluminum compounds, calcium sulfate, calcium carbonate, etc., which are clogging substances of the reverse osmosis membrane, so reverse placement by placing a reverse osmosis membrane in the latter stage of the aluminum removal device. While suppressing clogging of the osmotic membrane, treated water with higher purity can be obtained.

  Next, the aluminum removal apparatus based on this invention is demonstrated in more detail based on an Example. In addition, this invention is not limited by these Examples.

[Example 1]
The aluminum removing apparatus shown in FIG. 1 was assembled. As the ion exchange apparatus 2, Na type strongly acidic cation exchange resin (trade name “Amberlite (registered trademark) IR120B Na”, manufactured by Dow Chemical Co., Ltd.) 100 mL and Cl type strongly basic anion exchange resin (trade name “Amberlite ( (Registered Trademark) IRA-400 Cl ”(manufactured by Dow Chemical Co., Ltd.) 300 mL was mixed into a mixed bed and packed into a resin column (inner diameter 25.4 mm, length 1000 mm). To such a resin column, city A tap water (pH 7.4, electrical conductivity 180 μS / cm) having a dissolved aluminum concentration of 0.04 mg / L and a bicarbonate ion concentration of 42 mg CaCO ₃ / L was supplied at a flow rate of 18 L / L. Water was passed for about 8 hours under the condition of h. This condition corresponds to passing water in an amount 45 times the volume of the resin per hour, that is, SV = 45 h ⁻¹ . The dissolved aluminum concentration and pH in the treated water flowing out from the resin column were examined. In common with each example and comparative example, ICP (inductively coupled plasma) emission spectrometry was used for measurement of the dissolved aluminum concentration, and acid titration was used for measurement of the bicarbonate ion concentration.

  The transition of dissolved aluminum concentration in the treated water is shown in Table 1, and the transition of pH in the treated water is shown in FIG.

  As shown in Table 1, it can be seen that the dissolved aluminum concentration in the treated water was less than 0.01 mg / L from the beginning of water flow, and the dissolved aluminum was sufficiently removed. The pH of the treated water also decreased to about pH 6 at the beginning of water flow, but quickly recovered to near pH 7, and the pH value was stabilized.

[Comparative Example 1]
The aluminum concentration and pH in the treated water when aluminum was removed using only the Cl-type strongly basic anion exchange resin were examined.

A resin column (inner diameter: 25.4 mm, length: 1000 mm) was packed with 400 mL of Cl-type strongly basic anion exchange resin (trade name “Amberlite (registered trademark) IRA-400 Cl”, manufactured by Dow Chemical Co., Ltd.). The same city A tap water as ¹ was passed for about 9 hours under the conditions of SV = 45 h ⁻¹ and a flow rate of 18 L / h. The transition of dissolved aluminum concentration in the treated water is shown in Table 2, and the transition of pH in the treated water is shown in FIG.

  As shown in Table 2, the concentration of dissolved aluminum in the treated water was 0.01 mg / L at the beginning of water flow, and the removal rate of aluminum was slightly lower than that in Example 1. In addition, the pH of the treated water dropped to about 5 at the beginning of the water flow, and the recovery thereafter was slow, and was about 6.5 at the time of water flow for 8 hours.

[Comparative Example 2-1]
The aluminum concentration in the treated water was investigated when aluminum was removed using only the Na-type strongly acidic cation exchange resin.

A resin column (inner diameter 25.4 mm, length 1000 mm) was charged with 400 mL of Na-type strongly acidic cation exchange resin (trade name “Amberlite (registered trademark) IR120B Na”, manufactured by Dow Chemical Co., Ltd.). The city A tap water was passed for about 150 minutes under conditions of SV = 45 h ⁻¹ and a flow rate of 18 L / h. Table 3 shows the transition of the dissolved aluminum concentration in the treated water.

  When the pH was about 7, it was found that dissolved aluminum in the water to be treated could hardly be removed only by the Na-type strongly acidic cation exchange resin.

[Comparative Example 2-2]
Similar to Comparative Example 2-1, the aluminum concentration in the treated water when the aluminum was removed using only the Na-type strongly acidic cation exchange resin was examined. A resin column (inner diameter: 14 mm, length: 1000 mm) is filled with 100 mL of Na-type strongly acidic cation exchange resin (trade name “Amberlite (registered trademark) IR120B Na”, manufactured by Dow Chemical Co., Ltd.). City tap water (pH 7.8, electrical conductivity 370 μS / cm) was passed for about 140 minutes under conditions of SV = 48 h ⁻¹ and a flow rate of 4.8 L / h. The dissolved aluminum concentration in city B tap water was 0.05 mg / L, and the bicarbonate ion concentration was 46 mg CaCO ₃ / L. Table 4 shows the transition of the dissolved aluminum concentration in the treated water.

  Even when the pH exceeded 7 and was close to 8, it was found that dissolved aluminum in the water to be treated could hardly be removed only by the Na-type strongly acidic cation exchange resin.

[Example 2]
The mixing ratio of Na-type strongly acidic cation exchange resin and Cl-type strongly basic anion exchange resin in the ion exchange resin layer in the mixed bed was examined. Volume K Na-type strongly acidic cation exchange resin (trade name “Amberlite (registered trademark) IR120B Na”, manufactured by Dow Chemical) and volume A Cl-type strongly basic anion exchange resin (trade name “Amberlite (registered) (Trademark) IRA-400 Cl ”(manufactured by Dow Chemical Co., Ltd.) was mixed to form an ion exchange resin layer in a mixed bed and packed in a resin column. At this time, four resin columns having a volume ratio K: A of 1: 1, 1: 5, 1: 7, and 1: 9 were prepared. For reference, a resin column filled only with an anionic resin was also prepared.

To these five types of resin columns, the city water (pH 7.2, electrical conductivity 180 μS / cm) having a dissolved aluminum concentration of 0.02 mg / L and a bicarbonate ion concentration of 47 mg CaCO ₃ / L was converted into SV. Water was passed under the condition of = 45 h ⁻¹ and the pH of the treated water flowing out from the resin column was measured. FIG. 5 shows the transition of pH according to the water flow time, and FIG. 6 shows the same data as FIG. 5 converted into the transition of pH according to the water flow rate per anion exchange resin in the resin column. It shows.

  It can be seen that, in the range of K: A = 1: 1 to 1: 5, the pH quickly recovers to around 7 from the decrease in pH immediately after passing water, compared to the case where only the anion exchange resin is used. In addition, when K: A = 1: 7 or more, rapid recovery of pH is not observed, but since cation exchange resin exists, dissolved aluminum in an anionic form is removed by cation exchange resin. It is possible to improve the quality of treated water.

DESCRIPTION OF SYMBOLS 1,12 Raw water tank 2,10 Ion exchange apparatus 3,22a-22c Pump 4,30 Ion exchange resin layer 14 Regenerant storage tank 16 Treated water tank 20a-20j Piping 21a-21j Valve 24 Collector

Claims (10)

In a method for removing aluminum from water to be treated,
The treated water is passed through an ion exchange resin layer in which a salt-type strongly acidic cation exchange resin of an alkali metal or an alkaline earth metal and a Cl-type strongly basic anion exchange resin are mixed. Aluminum removal method.   2. The method for removing aluminum according to claim 1, wherein in the ion exchange resin layer, a ratio of a volume of the Cl-type strongly basic anion exchange resin to a volume of the salt-type strongly acidic cation exchange resin is 5 or less.   2. The method for removing aluminum according to claim 1, wherein in the ion exchange resin layer, a ratio of a volume of the Cl-type strongly basic anion exchange resin to a volume of the salt-type strongly acidic cation exchange resin is 3 or less.   The method for removing aluminum according to claim 2 or 3, wherein, in the ion exchange resin layer, a ratio of a volume of the Cl-type strongly basic anion exchange resin to a volume of the salt-type strongly acidic cation exchange resin is 1 or more.   The aluminum removal method according to any one of claims 1 to 4, wherein the salt-type strongly acidic cation exchange resin is a Na-type strongly acidic cation exchange resin. In an aluminum removing apparatus for removing aluminum from water to be treated,
An aluminum having an ion exchange device through which the water to be treated is passed through a mixed bed of a salt-type strongly acidic cation exchange resin of alkali metal or alkaline earth metal and a Cl-type strongly basic anion exchange resin Removal device.   The aluminum removal apparatus according to claim 6, wherein in the ion exchange apparatus, a ratio of a volume of the Cl-type strongly basic anion exchange resin to a volume of the salt-type strongly acidic cation exchange resin is 5 or less.   The aluminum removing apparatus according to claim 6, wherein, in the ion exchange apparatus, a ratio of a volume of the Cl-type strongly basic anion exchange resin to a volume of the salt-type strongly acidic cation exchange resin is 3 or less.   The aluminum removal apparatus according to claim 7 or 8, wherein in the ion exchange apparatus, a ratio of a volume of the Cl-type strongly basic anion exchange resin to a volume of the salt-type strongly acidic cation exchange resin is 1 or more.   The aluminum removal apparatus according to any one of claims 6 to 9, wherein the salt-type strongly acidic cation exchange resin is a Na-type strongly acidic cation exchange resin.

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