JP6109999B1 - Water treatment method and water treatment system - Google Patents

Abstract

Provided is a water treatment method capable of simultaneously adsorbing multiple types of metal ions in water to be treated and removing them efficiently and easily and reducing the amount of sludge generated after treatment. A water treatment method for removing at least a part of the ions from water to be treated containing ions to be removed. An ion adsorbing material that adsorbs ions and an aluminum compound are brought into contact with water to be treated under conditions of pH 8.0 or higher, and then a polymer flocculant is added to the water to be treated. It is a powdery product, particulate matter, or pellet containing carbonate and at least one of an oxide and a hydroxide. [Selection figure] None

Description

  The present invention relates to a water treatment method capable of adsorbing and removing metal ion components such as manganese, nickel, and zinc in water to be treated, and a water treatment system used therefor.

  Industrial wastewater generated by industrial production contains various chemical substances used in the production process. In many cases, these chemical substances are ionized by ionization in water. Moreover, about various elements which comprise these chemical substances, there are concerns about the influence on the health and the influence on the ecosystem. For this reason, the minimum concentration that can be discarded is regulated by law for some elements.

  As a method for removing metals contained in industrial wastewater, an adsorption method, an ion exchange method and the like are known in addition to a hydroxide coprecipitation method. Among these methods, the coprecipitation separation method in which iron hydroxide is generated and separated using an iron salt is best known.

  Examples of techniques related to the removal of metal ions in wastewater include a method of adsorbing on a filter impregnated with a chelating agent (Patent Document 1) and a two-stage hydroxide coprecipitation method using calcium salt and iron salt. (Patent Document 2) and the like are known. In addition, a solvent extraction method using an organic solvent that is hardly soluble in water (Patent Document 3), a method of removing manganese in water to be treated by a membrane separation method (Patent Document 4), and wastewater using oxidation / reduction reactions A method for removing manganese (Patent Document 5) is also known. Furthermore, a heavy metal ion remover comprising semi-calcined dolomite in which calcium oxide and magnesium oxide are controlled to a predetermined content as an active ingredient, and a wastewater treatment method using this remover have been proposed (Patent Document 6). In addition, as a technique relevant to the removal of halogen ions in waste water, for example, an ion exchange method and a precipitation separation method are known.

Japanese Patent Laid-Open No. 2004-082093 Japanese Patent Laid-Open No. 9-192777 JP-A-11-99301 Japanese Patent Laid-Open No. 9-057263 JP 2007-31479 A JP 2011-240325A

  However, in the methods proposed in the above-mentioned Patent Documents 1 to 5, it is difficult to remove a plurality of types of metal ions at the same time. Although it is possible to remove a plurality of types of metal ions at the same time by the membrane separation method, it has been difficult to employ for small-scale wastewater treatment due to high cost. Moreover, since it is necessary to use a large amount of organic solvent in the solvent extraction method, there has been a problem that it takes time to process the organic solvent used for extraction. Furthermore, since it is necessary to pay sufficient attention to the environmental impact, it has been difficult to discharge the treated wastewater as it is.

  In addition, if the removal agent of the heavy metal ion proposed by patent document 6 was used, it was possible to remove the multiple types of metal ion in to-be-processed water simultaneously. However, in order to remove metal ions in the water to be treated until the concentration is below a certain concentration, it is necessary to add a large amount of removing agent to the water to be treated. For this reason, a large amount of sludge is generated after the treatment, and the burden on the post-treatment and the environment is excessive.

  The present invention has been made in view of such problems of the prior art, and the problem is that a plurality of types of metal ions in the water to be treated are simultaneously adsorbed and removed efficiently and easily. It is possible to provide a water treatment method capable of reducing the amount of sludge generated after treatment and a water treatment system used therefor.

That is, according to the present invention, the following water treatment method is provided.
[1] A water treatment method for removing at least a part of the ions to be removed from water to be treated containing at least one of metal ions and fluorine ions selected from the group consisting of manganese, nickel, and zinc. And a step of adding a polymer flocculant to the water to be treated after contacting the ion adsorbing material and the aluminum compound for adsorbing the ions with the water to be treated under a condition of pH 8.0 or higher. The amount of the aluminum compound used is 0.0025% by mass or more based on the water to be treated, and the amount of the polymer flocculant used is 0.00025% by mass or more based on the water to be treated. There, the ion adsorption material, and a carbonate, powdered containing an oxide, a particulate material, or Ri pellets der, the carbonate, calcium carbonate, magnesium And the oxide is calcium oxide, and the content ratio of the oxide in the ion adsorbing material is 0.01 to 0.15% by mass Ru water treatment process.
[2 ] The water treatment method according to [1], wherein the ion adsorbing material is at least one of a fired product of shells and a fired product of limestone.
[ 3 ] The water treatment method according to [1] or [2] , wherein the aluminum compound is at least one selected from the group consisting of a water-soluble chloride, a water-soluble sulfate, and a water-soluble phosphorus oxide.

Moreover, according to this invention, the water treatment system shown below is provided.
[ 4 ] Water used for removing at least a part of the ions to be removed from water to be treated containing at least one of metal ions and fluorine ions selected from the group consisting of manganese, nickel, and zinc. A treatment system comprising a treatment unit into which a polymer flocculant is charged after contacting an ion adsorbing material and an aluminum compound that adsorb the ions with the water to be treated under conditions of pH 8.0 or more, The amount of the aluminum compound used is 0.0025% by mass or more with respect to the water to be treated, and the amount of the polymer flocculant used is 0.00025% by mass or more with respect to the water to be treated. the ion-adsorbing material, and a carbonate, powdered containing an oxide, a particulate material, or Ri pellets der, the carbonate, calcium carbonate It is at least one of magnesium carbonate and magnesium carbonate, and the oxide is calcium oxide, and the content ratio of the oxide in the ion adsorbing material is 0.01 based on the whole ion adsorbing material. 0.15 wt% der Ru water treatment system.

  According to the present invention, a water treatment method capable of simultaneously adsorbing a plurality of types of metal ions in water to be treated and removing them efficiently and easily, and capable of reducing the amount of sludge generated after treatment, and A water treatment system used therefor can be provided.

In Example 1, it is a figure which shows the state of solid-liquid separation after adding a polymer flocculent.

  Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments.

<Water treatment method>
The water treatment method of the present invention is a method of removing at least a part of ions from water to be treated containing ions to be removed. The ion adsorbing material and the aluminum compound that adsorb ions are subjected to a pH of 8.0 or more. After making it contact with to-be-processed water below, it has the process of adding a polymer flocculent to to-be-processed water. The ion adsorbing material (hereinafter also simply referred to as “adsorbing material”) is a powder, particulate, or pellet containing carbonate and at least one of an oxide and a hydroxide. The details will be described below.

(Processing process)
The water treatment method of the present invention comprises a step of adding a polymer flocculant to the water to be treated (treatment step) after contacting the ion adsorbing material and the aluminum compound with the water to be treated under a condition of pH 8.0 or higher. Have. The ion-adsorbing material is a powder, particulate, or pellet containing carbonate and at least one of an oxide and a hydroxide.

  Since the ion adsorbing material is a material that can adsorb metal ions such as manganese (Mn), nickel (Ni), zinc (Zn), and iron (Fe), only the ion adsorbing material is simply applied to the water to be treated. It is possible to adsorb and remove ions in the water to be removed to some extent by bringing them into contact with each other. However, for example, when ions such as heavy metals are to be removed until reaching a disposable ion concentration stipulated by law, it is necessary to add a relatively large amount of ion adsorbing material to the water to be treated. is there. For this reason, a large amount of used ion-adsorbing material is generated as sludge after the treatment, so that it takes time for solid-liquid separation after the treatment and an excessive burden is generated in the disposal of the separated sludge. End up.

  On the other hand, in the treatment process of the water treatment method of the present invention, as described above, not only the ion-adsorbing material but also the aluminum compound is brought into contact with the water to be treated. Further, the pH of the water to be treated when the ion adsorbing material and the aluminum compound are brought into contact is controlled under a condition of 8.0 or more. Furthermore, after bringing the ion-adsorbing material and the aluminum compound into contact with the water to be treated, a polymer flocculant is added to the water to be treated. By treating the water to be treated in this way, the amount of the ion adsorbing material used can be greatly reduced as compared with the case where only the ion adsorbing material is simply put into the water to be treated. For this reason, according to the water treatment method of the present invention, the amount of sludge generated by the treatment of the water to be treated can be greatly reduced, the solid-liquid separation after the treatment is easy, and the running cost required for the treatment is reduced. Reduction is also possible.

(Ion adsorption material)
The adsorbing material used in the water treatment method of the present invention is a component that adsorbs and removes ions such as metal ions in the water to be treated using adsorption of hydroxide generated from ions such as metal ions. Table 1 shows the hydrogen ion concentration (pH) generated by the hydroxide calculated from the solubility product (Ksp value) of the metal hydroxide.

For example, the basis for calculating the hydroxide formation pH from the solubility product of aluminum hydroxide (Al (OH) ₃ ) is as follows. The dissociation equilibrium of Al (OH) ₃ is represented by the following formula (1).

  The relationship between the above formula (1) and the solubility product (Ksp value) is expressed by the following formula (2).

Since Al (OH) ₃ is generated when the relationship of the following formula (3) is satisfied, the above formula (2) is expressed as the following formulas (4) and (5).

On the other hand, since the dissociation equilibrium of H ₂ O is represented by the following formula (6), the following formula (7) is derived from the above formula (5) and the following formula (6).

  Since the pH of the water to be treated is represented by the following formula (8), the hydroxide generation pH of aluminum (Al) can be calculated from the above formula (7) as the following formula (9).

  The adsorbing material used in the water treatment method of the present invention contains a carbonate and at least one of an oxide and a hydroxide. As the carbonate, calcium carbonate, magnesium carbonate, magnesium calcium carbonate, manganese carbonate, or the like can be used. Especially, as carbonate, calcium carbonate, magnesium carbonate, and magnesium carbonate (so-called dolomite) are preferable, and at least one of calcium carbonate and magnesium carbonate is more preferable. As the oxide, calcium oxide, magnesium oxide, or the like can be used. Of these, calcium oxide is preferable as the oxide. As the hydroxide, calcium hydroxide, magnesium hydroxide, or the like can be used. Of these, calcium hydroxide is preferred as the hydroxide.

  When the adsorbing material is composed of calcium carbonate, calcium oxide or the like, it is preferable that the adsorbing material is composed of shells, limestone, fish bones, etc., which are natural products that are easily available. In addition, when comprising an adsorbent material using natural products, such as a shell, limestone, and a fish bone, it is preferable to decompose the organic substance contained in these natural products by heat processing etc. In addition, since the adsorbing material is in the form of powder, particles, or pellets, it has a large surface area and is excellent in ion adsorption efficiency.

  The adsorbing material preferably contains a carbonate such as calcium carbonate or magnesium carbonate and an oxide such as calcium oxide. The adsorbing material is preferably substantially composed of carbonate and oxide. When the adsorbing material contains carbonate and oxide, the content ratio of the oxide is preferably 0.01% by mass or more, and 0.03% by mass or more based on the entire adsorbing material. Is more preferable and 0.05 mass% or more is particularly preferable. If the content ratio of the oxide such as calcium oxide is less than 0.01% by mass, it becomes difficult to sufficiently increase the pH of the water to be treated. It tends to be inefficient. The upper limit of the oxide content is not particularly limited, but is preferably 0.15% by mass or less, more preferably 0.12% by mass or less, based on the entire adsorbent material, It is particularly preferable that the content be 1% by mass or less. When the content ratio of the oxide such as calcium oxide is more than 0.15% by mass, the pH of the water to be treated may become too high, and it may be difficult to discharge the treated waste water as it is.

  The adsorbing material is preferably in the form of a powder or particulate having a particle size in the range of 0.01 to 2.0 mm. By using a powdery or particulate adsorbing material having a particle size in the above range, the ion adsorption efficiency and the like can be further increased.

(Aluminum compound)
In the water treatment method of the present invention, the aluminum compound is brought into contact with the water to be treated together with the ion adsorbing material. By bringing the aluminum compound into contact with the water to be treated, the fine adsorbent material can be settled and the removal efficiency can be improved. Furthermore, by using an aluminum compound, it is possible to effectively adsorb and remove fluorine ions among halogen ions. As the aluminum compound, it is preferable to use at least one water-soluble aluminum compound selected from the group consisting of water-soluble chlorides, water-soluble sulfates, and water-soluble phosphates. The water-soluble aluminum compound is preferably a compound that is easily ionized when dissolved in water, such as aluminum chloride or aluminum sulfate.

  The amount of the aluminum compound used is preferably 0.0025% by mass or more, more preferably 0.0025 to 0.0715% by mass with respect to the water to be treated. If the amount of aluminum compound used is too small, it may be difficult to improve the removal efficiency and the effect of removing fluorine ions may be insufficient.

(PH)
In the treatment step of the water treatment method of the present invention, the ion-adsorbing material and the aluminum compound are brought into contact with the water to be treated under the condition of pH 8.0 or more, preferably under the condition of pH 8.0 to 9.0. By bringing the ion adsorbing material and the aluminum compound into contact with the water to be treated under the condition of pH 8.0 or higher, the adsorption efficiency of metal ions in the water to be treated can be increased, and the amount of the adsorbing material used can be reduced. It becomes possible to reduce the amount of sludge generated after the treatment. If the pH is less than 8.0, the ion adsorption efficiency cannot be increased. On the other hand, if the pH is too high, it may be difficult to discharge the treated wastewater as it is. In addition, pH of to-be-processed water can be suitably adjusted, for example by setting the usage-amount (usage ratio) of an ion adsorption material and an aluminum compound.

(Polymer flocculant)
In the water treatment method of the present invention, after bringing the ion-adsorbing material and the aluminum compound into contact with the water to be treated, a polymer flocculant is added to the water to be treated. By adding the polymer flocculant to the water to be treated, the fine adsorbent material can be agglomerated and the removal efficiency can be improved. Further, by adding the polymer flocculant to the water to be treated, the amount of the adsorbing material required for adsorbing and removing the ions of the water to be treated to a desired level can be greatly reduced.

  The amount of the polymer flocculant used is preferably 0.00025% by mass or more, more preferably 0.00025 to 0.001% by mass with respect to the water to be treated. If the amount of the polymer flocculant used is too small, it may be difficult to improve the removal efficiency, and the adsorbing material required to adsorb and remove ions to be treated to a desired level. It may be difficult to reduce the amount.

  As the polymer flocculant, an anionic polymer flocculant, a cationic polymer flocculant, a nonionic polymer flocculant, and the like can be used. Among these, it is preferable to use an anionic polymer flocculant. Examples of the anionic polymer flocculant include sodium polyacrylate, a copolymer of sodium acrylate and acrylamide, polysodium methacrylate, a copolymer of sodium methacrylate and acrylamide, and the like. Examples of cationic polymer flocculants include acrylate polymer flocculants, methacrylate polymer flocculants, polyvinylamidines containing amide groups, nitrile groups, amine hydrochlorides, formamide groups, and polyacrylamide Mannich modified products. be able to. Examples of the nonionic polymer flocculant include polyacrylamide and polyethylene oxide.

<Water treatment system>
The water treatment system of the present invention is a system used for removing at least part of ions from water to be treated containing ions to be removed, and the above-mentioned ion-adsorbing material and aluminum compound have a pH of 8.0 or more . A treatment unit into which a polymer flocculant is charged after contacting with water to be treated under conditions is provided. Details of the water treatment system will be described below.

  Examples of the method of bringing the adsorbent material and aluminum into contact with the water to be treated include the same method as the method of purifying water using a general ion exchange resin. For example, a column type or batch type treatment method may be used. is there. That is, as a processing unit for bringing the adsorbing material and aluminum into contact with the water to be treated, there are a column filled with the adsorbing material, a batch tank filled with the adsorbing material, and the like.

  In the column-type treatment method, for example, a column in which an adsorbent material is packed is passed through a column in which an aluminum compound is added to water to be treated. As a result, various ions are converted into solid substances by reaction with the adsorbing material (pH of metal ions and coordination bond reaction of halogen ions), and at least some (preferably most) of the ions are adsorbed and removed. Treated water can flow out of the column. What is necessary is just to set suitably the liquid flow rate to a column with the quantity of the ion in to-be-processed water. Specifically, it is preferable to pass the liquid so that the SV ratio (ratio of the flow rate per unit volume) is about 4 to 10.

  In the batch type treatment method, for example, the adsorbing material and the aluminum compound are directly charged into a container such as a batch tank containing the treated water, and the treated water and the adsorbing material are brought into contact with each other. Moreover, it is preferable to mix and stir the water to be treated and the adsorbing material using a stirrer such as a propeller stirrer, because the adsorption efficiency can be improved. If a polymer flocculant is added after a certain period of time, and further stirred, then solid-liquid separation is performed by filtration or filter press to obtain treated water from which at least a part (preferably most) of various ions have been removed. be able to.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. In the examples and comparative examples, “parts” and “%” are based on mass unless otherwise specified.

Example 1
99.9 parts pulverized product of scallop shell (low temperature baked scallop shell) fired at 500 ° C., 0.05 part pulverized material of scallop shell (high temperature baked scallop shell) fired at a temperature of 850 ° C. or more, and 0.05 part of dolomite The adsorbent material having a particle size of 0.2 to 0.4 mm was prepared by mixing the parts. Moreover, 200 mL of test solutions containing each ion of manganese, nickel, zinc, and fluorine were prepared. The adsorbing material was added to the test solution so as to be 0.05%, 0.10%, 0.15%, 0.20%, 0.25%, and 0.30%, respectively. Then, 2 mL of 20% aqueous aluminum sulfate solution was added and stirred for 20 minutes using a stirrer. Thereafter, the polymer flocculant (trade name “Nakaflock”, manufactured by Mitsui Chemicals Aqua Polymer Co., Ltd.) was added to about 0.00075% and stirred. After leaving for 10 minutes, it was filtered to obtain a filtrate. The residual concentration of each element in the obtained filtrate was quantified by ICP-OES method and absorptiometry. Further, the pH of the filtrate was measured. The results are shown in Table 2. Moreover, the state of solid-liquid separation after adding a polymer flocculant is shown in FIG.

  As shown in Table 2, not only adsorption materials containing low-temperature fired scallop shells, high-temperature fired scallop shells, and dolomite, but also aluminum ions, which are water-soluble aluminum compounds, can be used not only for metal ions but also for fluorine ions. It can also be seen that it can be removed simultaneously and efficiently.

(Example 2)
The adsorbing material and the test solution used in Example 1 were used, and the adsorbing material was added to the test solution so as to be 0.15%. Next, 20% aqueous aluminum sulfate solution was added in amounts such that the pH of the test solution was 8.0, 8.2, and 8.4, respectively. After stirring for 20 minutes using a stirrer, a polymer flocculant (trade name “Nakaflock”, manufactured by Mitsui Chemicals Aqua Polymer Co., Ltd.) was added to the test solution so as to be 0.00075% and stirred. After leaving for 10 minutes, it was filtered to obtain a filtrate. The residual concentration of each element in the obtained filtrate was quantified by ICP-OES method and absorptiometry. Moreover, pH of the filtrate after a process was measured. The results are shown in Table 3.

(Comparison of the amount of adsorbent used)
200 mL of a test solution containing manganese, nickel, zinc, and fluorine ions was prepared. The adsorbing material used in Example 1 was added to the test solution so as to be 0.5%, 1.0%, and 2.0%, respectively. Subsequently, it stirred for 20 minutes using the stirrer, without adding aluminum sulfate aqueous solution. Thereafter, a polymer flocculant (trade name “Nakafloc”, manufactured by Mitsui Chemicals Aqua Polymer Co., Ltd.) was added to the test solution so as to be about 0.00075% and stirred. After leaving for 10 minutes, it was filtered to obtain a filtrate. The residual concentration of each element in the obtained filtrate was quantified by ICP-OES method and absorptiometry. Further, the pH of the filtrate was measured. The results are shown in Table 4.

  As shown in Table 4, when aluminum sulfate was not added, it was necessary to add 0.5% of an adsorbing material to sufficiently adsorb each element in the test solution. In contrast, as shown in Table 3, when aluminum sulfate is added and the hydrogen ion concentration (pH) is in the range of 8.0 to 9.0, 0.15% of an adsorbing material is added. As a result, each element in the test solution was sufficiently adsorbed. From the above, it can be seen that the amount of adsorbing material required, that is, the amount of generated sludge can be reduced by adding aluminum sulfate and adjusting the pH of the water to be treated to a predetermined range.

(Example 3)
Using the adsorbent material and the test solution used in Example 1 above, the adsorbent material was added to the test solution so that the addition rate shown in Table 5 was obtained (however, in “Example 1”, the adsorbent material was added). Not) Next, 20% aluminum sulfate aqueous solution in the amounts shown in Table 5 was added to the test solutions of Examples 4, 7, and 8. After stirring for 20 minutes using a stirrer, a polymer flocculant (trade name “Nakafloc”, manufactured by Mitsui Chemicals Aqua Polymer Co., Ltd.) was added to each of Examples 5 to 8 so that the addition ratios shown in Table 5 were obtained. And stirred. Each was allowed to stand until solid-liquid separation, and then filtered to obtain a filtrate. The residual concentration of each element in the obtained filtrate was quantified by ICP-OES method and absorptiometry. Moreover, pH of the filtrate after a process was measured. The results are shown in Table 5.

  As shown in Table 5, even when the addition rate of the adsorbing material is the same, the case where the polymer adsorbent is added (Examples 7 and 8) is compared with the case where the polymer adsorbent is not added (Example 4). Thus, it can be seen that each element in the test solution can be more adsorbed. In addition, in order to adsorb each element to the same level as the case where the polymer flocculant and aluminum sulfate are added without adding the polymer flocculant and aluminum sulfate, 10 times or more amount of adsorbent material is used. It can be seen that there is a need (compare Example 3 and Example 8). Furthermore, it can be seen that the use of the polymer flocculant can significantly reduce the separation time (that is, the working process time).

(Dissolution test)
In Example 1, the entire amount of the precipitate collected by adding 0.25% of the adsorbent material (collected by solid-liquid separation after being aggregated with a polymer flocculant) was placed in a 1000 mL beaker. 500 mL of pure water was added and stirred for 6 hours using a magnetic stirrer. The concentration of each element in the supernatant was quantified by ICP-OES method and absorptiometry. The results are shown in Table 6.

  As shown in Table 6, it can be seen that any element (ion) adsorbed on the adsorbing material is hardly eluted in water, and the amount is within the environmental standard.

Claims (4)

A water treatment method for removing at least a part of the ions to be removed from water to be treated containing at least one of metal ions and fluorine ions selected from the group consisting of manganese, nickel, and zinc ,
And a step of adding a polymer flocculant to the water to be treated after contacting the ion adsorbing material and the aluminum compound for adsorbing the ions with the water to be treated under a pH of 8.0 or more,
The amount of the aluminum compound used is 0.0025% by mass or more with respect to the water to be treated, and the amount of the polymer flocculant used is 0.00025% by mass or more with respect to the water to be treated. ,
The ion-adsorbing material, and a carbonate, powdered containing an oxide, a particulate material or pellet der is,
The carbonate is at least one of calcium carbonate, magnesium carbonate, and magnesium calcium carbonate, and the oxide is calcium oxide,
The content of the oxide in the ion-adsorbing material, based on the total of the ion-adsorbing material, 0.01-0.15% by mass Ru water treatment process.   The water treatment method according to claim 1, wherein the ion adsorbing material is at least one of a fired product of shells and a fired product of limestone. The water treatment method according to claim 1 or 2 , wherein the aluminum compound is at least one selected from the group consisting of water-soluble chlorides, water-soluble sulfates, and water-soluble phosphates. A water treatment system used for removing at least a part of the ions to be removed from water to be treated containing at least one of metal ions and fluorine ions selected from the group consisting of manganese, nickel, and zinc There,
A treatment unit in which a polymer flocculant is added after contacting the ion-adsorbing material and the aluminum compound for adsorbing the ions with the water to be treated under the condition of pH 8.0 or more,
The amount of the aluminum compound used is 0.0025% by mass or more with respect to the water to be treated, and the amount of the polymer flocculant used is 0.00025% by mass or more with respect to the water to be treated. ,
The ion-adsorbing material, and a carbonate, powdered containing an oxide, a particulate material or pellet der is,
The carbonate is at least one of calcium carbonate, magnesium carbonate, and magnesium calcium carbonate, and the oxide is calcium oxide,
The content of the oxide in the ion-adsorbing material, based on the total of the ion-adsorbing material, 0.01-0.15% by mass Ru water treatment system.