JP6329916B2 - Method for treating acidic waste liquid containing metal ions and treatment apparatus for acidic waste liquid containing metal ions - Google Patents

Description

  The present invention relates to a method for treating an acidic waste liquid containing metal ions and an apparatus for treating an acidic waste liquid containing metal ions.

  Mine wastewater containing metal salts and acidic wastewater such as plating wastewater in the plating industry often contain heavy metals and exceed wastewater standards. As a method for treating wastewater containing heavy metals, there is a method in which a strongly acidic pH is raised to satisfy the pH with respect to wastewater standards, and dissolved heavy metals are precipitated and separated into solid and liquid as the pH rises. Yes (neutralization coagulation precipitation). For example, as shown in Patent Document 1, a step of deacidifying an acid waste solution with a subnucleic acid dialysis device, a step of neutralizing and separating the deoxidation solution, and neutralizing and separating the neutralized filtrate separated by neutralization and precipitation with an acid by an electrodialysis device. A method for regenerating an acid waste liquid comprising a step of regenerating to an alkali is known.

Japanese Patent Laid-Open No. 9-887

However, in the conventional method for treating acidic waste liquid, it is necessary to add a large amount of neutralizing agent to the wastewater containing heavy metals, and the cost for the neutralizing agent and the disposal cost of the generated sludge (sludge) are low. There are problems such as an increase.
Most of the sludge is landfilled at an industrial waste disposal site without being effectively used, but the capacity of the industrial waste disposal site is getting tighter year by year and the disposal cost continues to rise. Therefore, it is an urgent task to develop a method for treating acidic waste liquid that can reduce the amount of chemicals used and the sludge reduction by increasing the efficiency of the treatment technology.

  The present invention has been made in view of the above-described circumstances, and is directed to a method for treating an acidic waste liquid containing metal ions and an apparatus for treating an acidic waste liquid containing metal ions, in which the efficiency of neutralization coagulation sedimentation treatment has been improved. For the purpose of provision.

  As a result of diligent investigations to solve the above problems, the present inventor, prior to the step of neutralization coagulation sedimentation treatment, first, an acidic waste liquid is brought into contact with a cation exchange resin to obtain a desorbed liquid in which metal ions are concentrated. Then, this desorbed liquid is introduced into an electrodialyzer to obtain a concentrated water in which metal ions are further concentrated, and this concentrated water is subjected to a neutralized coagulation sedimentation process, thereby improving the efficiency of the neutralization coagulation sedimentation process. Has been found to be dramatically improved, and the present invention has been completed.

In order to solve the above problems, the present invention proposes the following means.
The treatment method of the acidic waste liquid containing the metal ion of the present invention,
A step A of contacting an acidic waste liquid containing metal ions with a cation adsorbent to adsorb the metal ions on the cation adsorbent; and the metal ions adsorbed on the cation adsorbent The step B for obtaining a desorption solution containing the metal ions by desorption from the step B2, the step B2 for adding alkali to the desorption solution, and the electrodialysis apparatus having an anion exchange membrane and a cation exchange membrane Step C for introducing concentrated liquid to obtain concentrated water having a concentration of the metal ions higher than the concentration of the metal ions in the desorbed liquid; Step D for neutralizing and coagulating precipitation of the concentrated water; It is characterized by having.
According to this invention, the metal ions of the liquid to be neutralized and coagulated and precipitated are concentrated, and the volume of the liquid to be neutralized and coagulated and precipitated is reduced significantly.
By reducing the hydrogen ion concentration in the desorbed liquid, the metal ion transfer efficiency in electrodialysis is increased.

The method for treating an acidic waste liquid containing metal ions according to the present invention comprises demineralized water obtained together with the concentrated water and having a concentration of the metal ions lower than the concentration of the metal ions in the desorbed liquid. It is preferable to have the process E made to contact with an ion adsorbent.
According to this invention, demineralized water is subjected to wastewater treatment in the same treatment system.

In order to solve the above problems, the present invention proposes the following means.
The processing apparatus for acidic waste liquid containing metal ions of the present invention,
An acidic waste liquid storage tank for storing an acidic waste liquid containing metal ions, an acidic waste liquid supplied from the acidic waste liquid storage tank, an adsorption tower having a cation adsorbent on which the metal ions are adsorbed, and adsorbed on the cation adsorbent Regenerative chemical solution introducing means for desorbing the metal ions from the cation adsorbent to obtain a desorbed solution containing the metal ions into the adsorption tower, and adding alkali to the desorbed solution An alkali addition means, an electrodialyzer for obtaining concentrated water in which the desorbed liquid is introduced and the concentration of the metal ions in the desorbed liquid is higher than the concentration of the metal ions, and the concentrated water are supplied. And a neutralization coagulation sedimentation facility for neutralizing coagulation sedimentation treatment of the concentrated water.
According to this invention, the metal ions of the liquid to be neutralized and coagulated and precipitated are concentrated, and the volume of the liquid to be neutralized and coagulated and precipitated is reduced significantly.
By reducing the hydrogen ion concentration in the desorbed liquid, the metal ion transfer efficiency in electrodialysis is increased.

An apparatus for treating an acidic waste liquid containing metal ions according to the present invention is obtained by adsorbing demineralized water obtained together with the concentrated water and having a concentration of the metal ions lower than the concentration of the metal ions in the desorbed liquid. It is preferable to provide a return tube that returns to the tower.
According to this invention, demineralized water is subjected to wastewater treatment in the same treatment system.

In the present invention, according to the method for treating an acidic waste liquid containing metal ions according to claim 1, the processing space is reduced, the cost of the neutralizing agent necessary for neutralizing concentrated water is greatly reduced, and the like. Highly efficient neutralization coagulation sedimentation treatment can be achieved, and acidic waste liquid containing metal ions can be treated with high efficiency.
According to the method for treating an acidic waste liquid containing metal ions according to claim 1 , since the power required for electrodialysis can be reduced, the acidic waste liquid containing metal ions can be treated with higher efficiency.
According to the method for treating an acidic waste liquid containing metal ions according to claim 2 , the acidic waste liquid containing metal ions can be treated with higher efficiency by improving the operating rate of the treatment facility.

In the present invention, according to the acidic waste liquid treatment apparatus containing metal ions according to claim 3 , the processing space is reduced, the cost of the neutralizing agent necessary for neutralizing concentrated water is greatly reduced, and the like. Highly efficient neutralization coagulation sedimentation treatment can be achieved, and acidic waste liquid containing metal ions can be treated with high efficiency.
According to the treatment apparatus for acidic waste liquid containing metal ions according to claim 3 , since the electric power required for electrodialysis can be reduced, the acidic waste liquid containing metal ions can be treated with higher efficiency.
According to the processing apparatus for acidic waste liquid containing metal ions according to claim 4 , the acidic waste liquid containing metal ions can be further efficiently processed by improving the operating rate of the processing equipment.

It is a flowchart which shows one Embodiment of the processing method of the acidic waste liquid containing the metal ion which concerns on this invention. It is a flowchart which shows one Embodiment of the processing method of the acidic waste liquid containing the metal ion which concerns on this invention. It is a flowchart which shows one Embodiment of the processing method of the acidic waste liquid containing the metal ion which concerns on this invention. It is a schematic block diagram which shows one Embodiment of the processing apparatus of the acidic waste liquid containing the metal ion which concerns on this invention. It is a schematic block diagram which shows one Embodiment of the processing apparatus of the acidic waste liquid containing the metal ion which concerns on this invention. It is a schematic block diagram which shows one Embodiment of the processing apparatus of the acidic waste liquid containing the metal ion which concerns on this invention. It is a schematic block diagram which shows one Embodiment of the processing apparatus of the acidic waste liquid containing the metal ion which concerns on this invention. It is a schematic diagram which shows a mode that several adsorption towers operate alternately. It is a figure which shows the predicted value of the material balance in the processing flow which electrolyzes the desorption liquid model liquid after alkali addition using two electrodialysis apparatuses, and the said processing flow. It is a figure which shows the predicted value of the material balance of the whole processing method of the mineral wastewater which concerns on this invention in an Example.

≪Method of treating acidic waste liquid containing metal ions≫
The method for treating an acidic waste liquid containing metal ions according to the present invention comprises contacting the acidic waste liquid containing metal ions with a cation exchange resin, and adsorbing the metal ions to the cation exchange resin; An electrodialyzer having an anion exchange membrane and a cation exchange membrane, wherein the metal ions adsorbed on the ion exchange resin are desorbed from the cation exchange resin to obtain a desorbed solution containing the metal ions; A step C of introducing the desorbed liquid to obtain concentrated water in which the concentration of the metal ions is higher than the concentration of the metal ions in the desorbed liquid; and a process D of neutralizing and coagulating precipitation of the concentrated water And having.

  Hereinafter, a method for treating an acidic waste liquid containing metal ions according to the present embodiment (hereinafter, sometimes referred to as “method for treating an acidic waste liquid”) will be described with reference to the drawings. The processing method of acidic waste liquid is not limited to the following embodiment.

(First embodiment)
FIG. 1 is a flowchart showing a method for treating acidic waste liquid according to this embodiment. As shown in FIG. 1, the acidic waste liquid treatment method of this embodiment is
An acidic waste liquid containing metal ions is brought into contact with a cation exchange resin, and the metal ions are adsorbed onto the cation exchange resin (adsorption onto the cation exchange resin in FIG. 1). Step B of desorbing the adsorbed metal ions from the cation exchange resin (desorption from the cation exchange resin in FIG. 1) to obtain a desorption solution containing the metal ions, an anion exchange membrane and a cation A step of introducing the desorbed liquid into an electrodialysis apparatus having an exchange membrane (electrodialysis in FIG. 1) to obtain concentrated water in which the concentration of the metal ions is higher than the concentration of the metal ions in the desorbed liquid. C and neutralization coagulation sedimentation treatment D of the concentrated water (neutralization coagulation sedimentation of FIG. 1).

In the present embodiment, the metal ion contained in the acidic waste liquid may be any metal ion, for example, iron ion (Fe ²⁺ , Fe ³⁺ ), aluminum ion (Al ²⁺ ), cadmium ion (Ca ²⁺ ). , Copper ion (Cu ²⁺ ), zinc ion (Zn ²⁺ ), magnesium ion (Mg ²⁺ ), lead ion (Pb ²⁺ ), mercury ion (Hg ²⁺ , Hg ⁺ ) nickel ion (Ni ²⁺ ), etc. Not limited to.

  From the viewpoint of neutralizing, coagulating and precipitating the metal dissolved in the liquid as the pH rises, in this embodiment, the pH of the acidic waste liquid to be treated is preferably pH 0 to 4, and pH 0 to 3 More preferably, it is more preferably pH 0-2.

  Specific examples of the acidic waste liquid include mineral waste water, plating waste liquid, and factory waste water. Mineral wastewater is the rainwater and groundwater that has fallen throughout the mine and leached from the ground via the mine. The composition of general acid mine wastewater is shown in Table 1 (M. Sengupta: “Environmental impacts of Mining”, Lewins Publishers, 1993 (excerpt)). The metal ion concentration varies, but the pH is 2-3.

(Process A)
Step A is a step in which an acidic waste liquid containing metal ions is brought into contact with a cation exchange resin to adsorb the metal ions onto the cation exchange resin.
In this embodiment, a cation exchange resin is used as the cation adsorbent.
As the cation exchange resin, a strong acid cation exchange resin and a weak acid cation exchange resin are known. In this embodiment, a strong acid cation exchange resin is preferable. For example, in the case of a strongly acidic cation exchange resin having a sulfonic acid group as an exchange group, when an acidic waste liquid containing metal ions is brought into contact with the cation exchange resin, hydrogen ions (H ⁺ ) and metal ions of the sulfonic acid groups are converted. As a result, the metal ions are adsorbed on the cation exchange resin.
Examples of other cation adsorbents include chelate resins that can chelate and adsorb cations. Examples of the chelate resin include iminodiacetic acid type chelate resin, polyamine type chelate resin, aminophosphate type chelate resin, and glucamine type chelate resin.
Only one kind of cation adsorbent may be used, or a plurality of kinds may be used in combination, or a combination of a cation exchange resin and a chelate resin may be used.

(Process B)
Step B is a step of obtaining a desorption liquid containing the metal ions by desorbing the metal ions adsorbed on the cation exchange resin from the cation exchange resin.
In order to desorb the metal ions from the cation exchange resin, an acid solution suitable for desorbing the metal ions from the cation exchange resin may be brought into contact with the cation exchange resin. Examples of the acidic solution include hydrochloric acid and a sulfuric acid aqueous solution, and a sulfuric acid aqueous solution is preferable. When an acidic solution is brought into contact with a cation exchange resin having adsorbed metal ions, the metal ions adsorbed on the ion exchange resin are exchanged with hydrogen ions in the acidic aqueous solution, and the metal ions adsorbed on the cation exchange resin are converted into the cation. Desorb from the exchange resin. The metal ions desorbed from the cation exchange resin are contained and eluted in the liquid component of the acidic solution to obtain a desorbed solution containing the metal ions.

In step A, when an acidic waste liquid containing metal ions is brought into contact with a cation exchange resin and the metal ions are continuously adsorbed to the cation exchange resin, the exchange of hydrogen ions and metal ions proceeds and the metal ions The exchangeable hydrogen ions are reduced, and the adsorption efficiency of metal ions on the ion exchange resin is reduced. Therefore, it is preferable to regenerate the ion exchange resin before the metal ion adsorption efficiency on the ion exchange resin is significantly reduced.
By desorbing metal ions from the cation exchange resin, the ion exchange resin is regenerated. Therefore, considering that the adsorption efficiency of metal ions on the ion exchange resin is lowered, it is preferable to move from step A to step B and regenerate the ion exchange resin.

By examining the type of acidic solution, the hydrogen ion concentration in the acidic solution, etc., the amount of acidic waste liquid contacted with the cation exchange resin to adsorb a predetermined amount of metal ions is more suitable for the cation exchange resin. It is possible to reduce the amount of acidic solution necessary to desorb a predetermined amount of adsorbed metal ions from the cation exchange resin.
Therefore, by passing through the process A and the process B, the density | concentration of the metal ion contained in a desorption liquid can be made higher than the density | concentration of the metal ion contained in an acidic waste liquid, and it passes through the process A and the process B. Thus, a desorbed liquid in which metal ions of the acidic waste liquid are concentrated can be obtained.

(Process C)
In step C, the desorption solution is introduced into an electrodialysis apparatus having an anion exchange membrane and a cation exchange membrane, and the concentration of the metal ions is higher than the concentration of the metal ions in the desorption solution. This is a process for obtaining water.
The electrodialysis apparatus of the present embodiment has a treatment tank partitioned by an anion exchange membrane and a cation exchange membrane, and an anode is disposed at one end in the treatment tank and a cathode is disposed at the other side. Is. The cation exchange membrane selectively permeates cations in the solution, and the anion exchange membrane selectively permeates the anions in the solution. A plurality of anion exchange membranes and cation exchange membranes are alternately arranged in the treatment tank.
When the desorption solution is introduced into the treatment tank of the electrodialysis machine and a voltage is applied to the desorption solution, cations (metal ions) move toward the cathode side and anions move toward the anode side. To do. Since a plurality of anion exchange membranes and cation exchange membranes are alternately arranged in the treatment tank, the concentration of cations (metal ions) and anions is higher than that of the desorbed liquid in a certain section. Concentrated water is stored, and deionized water having a lower cation (metal ion) and anion concentration than the desorbed liquid is stored in another compartment.

  Thus, it is possible to obtain concentrated water in which the concentration of the metal ions is higher than the concentration of the metal ions in the desorption liquid, and the acid waste liquid is obtained through the steps A, B, and C. Concentrated water in which the metal ions are further concentrated can be obtained.

(Process D)
Step D is a step of subjecting the concentrated water to neutralization aggregation precipitation.
Neutralization coagulation sedimentation can generate deposits, such as metal hydroxide, by raising the pH of concentrated water in which metal ions are dissolved. The pH value of the concentrated water can be appropriately determined in consideration of the value at which the target metal precipitates. For example, raising the pH of concentrated water to about pH 2-12 is mentioned.

  A neutralization coagulation precipitation treatment may be performed by appropriately adding a substance that promotes the precipitation of metal such as an aggregating agent or an adsorbent to the concentrated water.

  The produced precipitate is then separated from the concentrated water.

  According to the method for treating acidic waste liquid of this embodiment, the waste liquid to be electrodialyzed in Step C is subjected to direct electrodialysis of the acidic waste liquid by performing concentration of metal ions with a cation exchange resin in Step A and Step B. Compared with the case where it does, since the liquid volume of a desorption liquid is lower than the volume of an acidic waste liquid, the processing space for electrodialysis and the cost reduction are realizable.

The metal ion concentration per concentrated water after the process A, the process B and the process C is higher than the metal ion concentration per acidic waste liquid to be treated. Therefore, comparing the amount of liquid containing the same amount of metal ions, the amount of concentrated water is much smaller than the amount of acidic waste liquid. Therefore, compared to the case of directly neutralizing the acidic waste liquid, the amount of neutralizing agent used to neutralize the concentrated water is reduced, and a significant cost reduction can be realized. Furthermore, a reduction in the amount of generated sludge can be expected due to the improvement of the aggregation efficiency. Moreover, since the volume of the concentrated water is much lower than the volume of the acidic waste liquid, the processing space for neutralization coagulation precipitation can be reduced.
According to the acidic waste liquid treatment method of the present embodiment, a high-efficiency neutralization coagulation precipitation process can be achieved through these steps A to D, and metal ions can be removed from the acidic waste liquid with high efficiency. .

(Second Embodiment)
FIG. 2 is a flowchart showing the method for treating acidic waste liquid according to this embodiment. As shown in FIG. 2, the acidic waste liquid treatment method according to the present embodiment causes the acidic waste liquid containing metal ions to come into contact with a cation exchange resin to adsorb the metal ions on the cation exchange resin (FIG. 2). Step A), the metal ions adsorbed on the cation exchange resin are desorbed from the cation exchange resin (desorption from the cation exchange resin in FIG. 2), and the metal ions are desorbed. Step B for obtaining a desorbing solution containing the above, Step B2 for adding alkali to the desorbing solution (alkali addition in FIG. 2), and the desorbing solution in an electrodialyzer having an anion exchange membrane and a cation exchange membrane (Electrodialysis in FIG. 2) to obtain concentrated water having a concentration of the metal ions higher than the concentration of the metal ions in the desorbed solution, and neutralizing and coagulating sedimentation treatment of the concentrated water (Neutralization coagulation precipitation in Fig. 2) Having, and D.

  The method for treating an acidic waste liquid according to the second embodiment is such that the method for treating an acidic waste liquid according to the first embodiment further includes a step B2 of adding an alkali to the desorbed liquid. Hereinafter, although the processing method of the acidic waste liquid of 2nd Embodiment is demonstrated, description is abbreviate | omitted about the point which is common in the processing method of the acidic waste liquid of the said 1st Embodiment.

Since the desorbed liquid obtained through the steps A and B is obtained by bringing the acidic solution into contact with the cation exchange resin, a large amount of hydrogen ions derived from the acidic solution may be contained in the desorbed liquid. is there.
When this desorbed liquid is introduced into the electrodialysis device, the amount of hydrogen ions that move is larger than the amount of metal ions that are originally permeated through the ion exchange membrane and thus concentrated. It will be up.

In order to avoid this, a substance that reduces hydrogen ions in the desorption solution is added to the desorption solution. For example, by adding an alkali such as sodium hydroxide (NaOH), calcium carbonate (CaCO ₃ ), magnesium oxide (MgO) to the detachment solution, the pH of the detachment solution is raised and introduced into the electrodialyzer. It is possible to reduce the hydrogen ions in the desorbed liquid and reduce the power required for electrodialysis.

  The pH value of the desorbed liquid can be appropriately determined in consideration of the amount of hydrogen ions in the liquid. For example, the pH of the concentrated water is raised to the same level as the acidic waste liquid to be treated. As an example, the desorbed solution having a pH of 0.2 is raised to pH2.

  According to the method for treating acidic waste liquid of the second embodiment, the metal ion transfer efficiency can be increased by reducing the hydrogen ion concentration in the desorbed liquid, and the power required for electrodialysis can be reduced. Metal ions can be removed from acidic waste liquid with high efficiency.

(Third embodiment)
FIG. 3 is a flowchart showing the method for treating acidic waste liquid according to this embodiment. As shown in FIG. 3, in the method for treating acidic waste liquid of the present embodiment, an acidic waste liquid containing metal ions is brought into contact with a cation exchange resin to adsorb the metal ions on the cation exchange resin (FIG. 3). Step A), the metal ions adsorbed on the cation exchange resin are desorbed from the cation exchange resin (desorption from the cation exchange resin in FIG. 3), and the metal ions are desorbed. Step B for obtaining a desorbed solution containing alkoxide, Step B2 for adding alkali to the desorbed solution (addition of alkali in FIG. 3), and the desorbed solution in an electrodialyzer having an anion exchange membrane and a cation exchange membrane. (Electrodialysis in FIG. 3) to obtain a concentrated water in which the concentration of the metal ions is higher than the concentration of the metal ions in the desorbed liquid, and the concentrated water is neutralized by coagulation precipitation (Neutralization coagulation precipitation in Fig. 3) D and demineralized water obtained together with the concentrated water and having a metal ion concentration lower than the concentration of the metal ions in the desorbed liquid are brought into contact with the cation exchange resin (demineralized water in FIG. 3). Return) step E.

  The method for treating an acidic waste liquid according to the third embodiment is the same as the method for treating an acidic waste liquid according to the (second embodiment), which is obtained together with the concentrated water, and the metal ion concentration is higher than the concentration of the metal ions in the desorbed liquid. It has the process E which makes the demineralized water in which the density | concentration of ion was lowered | contacted with the said cation exchange resin. Hereinafter, the method for treating acidic waste liquid according to the third embodiment will be described. However, description of points common to the method for treating acidic waste liquid according to the first and second embodiments will be omitted.

  Demineralized water is assumed to contain metal ions at a concentration exceeding the metal ion discharge standard, although the concentration of the metal ions is lower than the concentration of the metal ions in the desorbed liquid. The Therefore, the deionized water may be brought into contact with the cation exchanger so that the metal ions contained in the demineralized water are adsorbed on the cation exchanger and the metal ions are removed from the demineralized water.

In the acidic waste liquid treatment method of this embodiment, the cation exchange resin used in step A is used, and demineralized water is brought into contact with the cation exchange resin.
Step E may be performed independently of the above steps A to D or may be performed simultaneously. For example, you may perform the process E and the process A simultaneously by making the liquid mixture which mixed demineralized water and acidic waste liquid contacted cation exchange resin.

  According to the method for treating acidic waste liquid of the third embodiment, the demineralized water obtained in Step C is returned to the cation exchange resin, and the liquid is re-contacted with the cation exchange resin, so that the waste water is discharged in the same treatment system. Since the treatment can be completed, the operating rate of the treatment facility can be improved, and the acidic waste liquid can be treated more efficiently.

≪Treatment equipment for acidic waste liquid containing metal ions≫
The processing apparatus for acidic waste liquid containing metal ions of the present invention,
An acidic waste liquid storage tank for storing an acidic waste liquid containing metal ions, an acidic waste liquid supplied from the acidic waste liquid storage tank, an adsorption tower having a cation adsorbent on which the metal ions are adsorbed, and adsorbed on the cation adsorbent Regenerative chemical liquid introduction means for desorbing the metal ions from the cation adsorbent to obtain a desorbed liquid containing the metal ions into the adsorption tower;
An electrodialyzer that obtains concentrated water into which the desorbed liquid has been introduced and the concentration of the metal ions in the desorbed liquid is higher than the concentration of the metal ions; the concentrated water is supplied; Neutralization coagulation sedimentation equipment for carrying out neutralization coagulation sedimentation treatment.

Hereinafter, the processing apparatus for acidic waste liquid containing metal ions according to the present embodiment (hereinafter sometimes referred to as “processing apparatus for acidic waste liquid”) will be described with reference to the drawings. The processing apparatus of acidic waste liquid is not limited to the following embodiment.
According to the acidic waste liquid treatment apparatus of the first embodiment, the acidic waste liquid treatment method of the first embodiment described above can be carried out. Hereinafter, although the processing method of the acidic waste liquid of 1st Embodiment is also demonstrated, referring a figure, the processing method of the acidic waste liquid of this invention is not limited to the method using the processing apparatus of the following acidic waste liquid.

(First embodiment)
FIG. 4 is a schematic configuration diagram showing an embodiment of an apparatus for treating acidic waste liquid containing metal ions according to the present invention. As shown in FIG. 4, the acidic waste liquid treatment apparatus 1 of the present embodiment includes:
An acidic waste liquid storage tank 10 for storing an acidic waste liquid containing metal ions, an adsorption tower 20 having a cation exchange resin to which the acidic waste liquid is supplied from the acidic waste liquid storage tank 10 and adsorbs the metal ions, and the cation exchange resin Regenerative chemical solution introduction means 40 and 41 for desorbing the metal ions adsorbed on the cation exchange resin to obtain a desorbed solution containing the metal ions into the adsorption tower; An electrodialyzer 50 for obtaining concentrated water in which a liquid is introduced and the concentration of the metal ions is higher than the concentration of the metal ions in the desorbed liquid, and the concentrated water is supplied to neutralize the concentrated water A neutralization coagulation sedimentation facility 60 for coagulation sedimentation treatment.

  The acidic waste liquid storage tank 10 stores an acidic waste liquid containing metal ions. A dust remover 11 is provided downstream of the acidic waste liquid storage tank 10. The dust remover 11 removes suspended substances (solid components) such as dust and dust contained in the acidic waste liquid. The acidic waste liquid stored in the acidic waste liquid storage tank 10 can be introduced into the dust remover 11 through the pipe 12.

An adsorption tower 20 having a cation exchange resin is provided downstream of the dust remover 11. An acidic waste liquid from which suspended substances are removed from the dust remover 11 can be introduced into the adsorption tower 20 via the pipe 13. When the acidic waste liquid is introduced into the adsorption tower 20, the acidic waste liquid comes into contact with the cation exchange resin, and the metal ions contained in the acidic waste liquid are adsorbed on the cation exchange resin.
Thus, the acidic waste liquid is introduced into the adsorption tower 20 and the acidic waste liquid is brought into contact with the cation exchange resin, so that the metal ions can be adsorbed on the cation exchange resin (step A in FIG. 1).

  Waste liquid that has passed through the adsorption tower 20 and has metal ions adsorbed by the cation exchange resin to reduce the metal ion concentration can be discharged through a pipe 22 connected to the adsorption tower 20.

The regenerative chemical solution storage tank 40 (regenerated chemical solution introduction means) is connected to the adsorption tower 20 via a regenerative chemical solution introduction pipe 41 (regenerated chemical solution introduction means). The regenerated chemical solution can be introduced into the adsorption tower 20 from the regenerated chemical solution storage tank 40 through the regenerated chemical solution introduction pipe 41. When the regenerative chemical solution is introduced into the adsorption tower 20, the regenerative chemical solution comes into contact with the cation exchange resin, and the metal ions adsorbed on the cation exchange resin are desorbed from the cation exchange resin.
A regenerative chemical solution is introduced into the adsorption tower 20, the regenerative chemical solution is brought into contact with a cation exchange resin, and the metal ions adsorbed on the cation exchange resin are desorbed from the cation exchange resin to contain the metal ions. A desorption liquid can be obtained (step B in FIG. 1).

  The desorbed liquid eluted from the adsorption tower 20 is sent to the desorbed liquid storage tank 30 through a pipe 21 connected to the adsorption tower 20.

The electrodialysis apparatus 50 is connected to the desorbed liquid storage tank 30 through a pipe 31. A detachment liquid can be introduced into the electrodialysis apparatus 50 from the detachment liquid storage tank 30 via a pipe 31. The electrodialysis apparatus 50 has a treatment tank partitioned with an anion exchange membrane and a cation exchange membrane, and an anode is disposed at one end in the treatment tank and a cathode is disposed at the other side. . The cation exchange membrane selectively permeates cations in the solution, and the anion exchange membrane selectively permeates the anions in the solution. A plurality of anion exchange membranes and cation exchange membranes are alternately arranged in the treatment tank (not shown).
When the desorption solution is introduced into the treatment tank of the electrodialysis apparatus 50 and a voltage is applied to the desorption solution, cations (metal ions) move toward the cathode side and anions move toward the anode side. Moving. Since a plurality of anion exchange membranes and cation exchange membranes are alternately arranged in the treatment tank, concentrated water having a higher cation and anion concentration than the desorbed liquid is provided in one section. Is stored, and deionized water having a lower cation and anion concentration than the desorbed liquid is stored in another compartment.
As described above, when the detachment liquid is introduced into the electrodialysis apparatus 50 and a voltage is applied to the detachment liquid, concentrated water having a metal ion concentration higher than the concentration of metal ions in the detachment liquid can be obtained. (Step C in FIG. 1).

The concentrated water is sent to the neutralization coagulation sedimentation facility 60 through the pipe 51. The concentrated liquid is introduced into the neutralization coagulation sedimentation facility 60, and the concentrated water is subjected to neutralization coagulation precipitation processing (step D in FIG. 1). Neutralization coagulation sedimentation equipment 60 is a neutralization tank for mixing concentrated water and a neutralizing agent, and the pH of concentrated water by mixing the mixed neutralizing agent by leaving a mixed liquid in which concentrated water and neutralizing agent are mixed. A sedimentation tank (not shown) for sedimenting the precipitate generated by the ascent.
Since the sediment settles at the bottom of the sedimentation tank, the sediment is taken out from the sedimentation tank as sludge (sludge) and transferred to a sludge treatment facility. The supernatant separated from the precipitate can be discharged from the settling tank through the pipe 61.

  As described above, according to the acidic waste liquid treatment apparatus 1 of the present embodiment, the waste liquid to be electrodialyzed in the electrodialysis apparatus is subjected to concentration of the metal ion concentration by the cation exchange resin in the adsorption tower. Compared with the case of direct electrodialysis, the volume of the desorbed liquid is lower than the volume of the acidic waste liquid, and the processing space for electrodialysis can be reduced and the cost can be reduced.

The acidic waste liquid is sequentially introduced into the adsorption tower having the cation exchange resin and the electrodialysis apparatus and processed, so that the metal ion concentration per concentrated liquid is equal to the metal ion concentration per acidic waste liquid to be treated. Increased compared to. Therefore, comparing the amount of liquid containing the same amount of metal ions, the amount of concentrated water is much smaller than the amount of acidic waste liquid. Therefore, compared to the case of directly neutralizing the acidic waste liquid, the amount of neutralizing agent used to neutralize the concentrated water is reduced, and a significant cost reduction can be realized. Furthermore, a reduction in the amount of generated sludge can be expected due to the improvement of the aggregation efficiency. Moreover, since the volume of the concentrated water is much lower than the volume of the acidic waste liquid, the processing space for neutralization coagulation precipitation can be reduced.
According to the acidic waste liquid treatment apparatus 1 of the present embodiment, highly efficient neutralization coagulation precipitation treatment can be achieved, and metal ions can be removed from the acidic waste liquid with high efficiency.

(Second Embodiment)
FIG. 5 is a schematic configuration diagram showing an embodiment of an apparatus for treating acidic waste liquid containing metal ions according to the present invention. As shown in FIG. 5, the acidic waste liquid treatment apparatus 2 of the present embodiment is
An acidic waste liquid storage tank 10 for storing an acidic waste liquid containing metal ions, an adsorption tower 20 having a cation exchange resin to which the acidic waste liquid is supplied from the acidic waste liquid storage tank 10 and adsorbs the metal ions, and the cation exchange resin Regenerative chemical solution introduction means 40 and 41 for desorbing the metal ions adsorbed on the cation exchange resin to obtain a desorbed solution containing the metal ions into the adsorption tower; Electrodialysis for obtaining concentrated water in which the concentration of the metal ions is higher than the concentration of the metal ions in the desorption solution by introducing the desorption solution into the alkali addition means 70 and 71 for adding alkali to the solution The apparatus 50 is provided with the neutralization coagulation sedimentation equipment 60 which is supplied with the concentrated water and performs the neutralization coagulation sedimentation treatment of the concentrated water.

  In the acidic waste liquid treatment apparatus of the second embodiment, the acidic waste liquid treatment apparatus of the (first embodiment) further includes an alkali addition means for adding alkali to the desorption liquid. Hereinafter, although the acidic waste liquid processing apparatus of 2nd Embodiment is demonstrated, description is abbreviate | omitted about the point which is common in the acidic waste liquid processing apparatus of the said 1st Embodiment.

  According to the acidic waste liquid treatment apparatus of the second embodiment, the above-described acidic waste liquid treatment method of the second embodiment can be carried out. Hereinafter, although the processing method of the acidic waste liquid of 2nd Embodiment is demonstrated, referring a figure, the processing method of the acidic waste liquid of this invention is not limited to the method using the processing apparatus of the following acidic waste liquid.

As shown in FIG. 5, the alkali storage tank 70 (alkali addition means) is connected to the desorbed liquid storage tank 30 via an alkali introduction pipe 71 (alkali addition means). The alkali can be introduced into the desorbed liquid storage tank 30 via the alkali introduction pipe 71.
When the alkali is introduced into the detachment liquid storage tank, it is mixed with the detachment liquid stored in the detachment liquid storage tank, and the alkali can be added to the detachment liquid (step B2 in FIG. 2). As a result, the pH of the desorbed liquid rises, hydrogen ions in the desorbed liquid introduced into the electrodialyzer are reduced, and the power required for electrodialysis can be reduced.

  According to the acidic waste liquid treatment apparatus 2 of the present embodiment, by reducing the hydrogen ion concentration in the desorbed liquid, the metal ion transfer efficiency can be increased and the power required for electrodialysis can be reduced. Electric power required for dialysis can be reduced, and metal ions can be removed from acidic waste liquid with higher efficiency.

(Third embodiment)
FIG. 6 is a schematic configuration diagram showing an embodiment of an apparatus for treating acidic waste liquid containing metal ions according to the present invention. As shown in FIG. 6, the acidic waste liquid treatment apparatus 3 of the present embodiment is
An acidic waste liquid storage tank 10 for storing an acidic waste liquid containing metal ions, an adsorption tower 20 having a cation exchange resin to which the acidic waste liquid is supplied from the acidic waste liquid storage tank 10 and adsorbs the metal ions, and the cation exchange resin Regenerative chemical solution introduction means 40 and 41 for desorbing the metal ions adsorbed on the cation exchange resin to obtain a desorbed solution containing the metal ions into the adsorption tower; Electrodialysis for obtaining concentrated water in which the concentration of the metal ions is higher than the concentration of the metal ions in the desorption solution by introducing the desorption solution into the alkali addition means 70 and 71 for adding alkali to the solution The apparatus 50, the neutralized coagulation sedimentation facility 60 to which the concentrated water is supplied and neutralizes the coagulated sediment, and the concentration of the metal ions in the desorbed liquid obtained together with the concentrated water. Also demineralized water concentration was lower the metal ion comprises a return pipe 52 for returning to the adsorption tower.

  In the acidic waste liquid treatment apparatus of the third embodiment, the acidic waste liquid treatment apparatus of the (second embodiment) further includes a return pipe for returning demineralized water to the adsorption tower. Hereinafter, although the acidic waste liquid processing apparatus of 3rd Embodiment is demonstrated, description is abbreviate | omitted about the point which is common in the acidic waste liquid processing apparatus of the said 1st and 2nd embodiment.

  According to the acidic waste liquid treatment apparatus of the third embodiment, the above-described acidic waste liquid treatment method of the third embodiment can be carried out. Hereinafter, although the processing method of the acidic waste liquid of 3rd Embodiment is also demonstrated, referring a figure, the processing method of the acidic waste liquid of this invention is not limited to the method using the processing apparatus of the following acidic waste liquid.

As shown in FIG. 6, the return pipe 52 is connected to the pipe 13, and the electrodialyzer 50 and the adsorption tower 20 are connected by the return pipe 52 and the pipe 13. Desalinated water produced by the electrodialyzer 50 can be introduced into the adsorption tower 20 via the return pipe 52 and the pipe 13.
Demineralized water can be introduced into the adsorption tower 20 and the demineralized water can be brought into contact with the cation exchange resin (step E in FIG. 3). As a result, even if the demineralized water contains metal ions at a concentration exceeding the metal ion discharge standard, the demineralized water is returned to the cation exchange resin and the liquid is re-contacted with the cation exchange resin. Can be made. Therefore, since the wastewater treatment can be completed in the same treatment system, the operation rate of the treatment facility can be improved and the acidic waste liquid can be treated with higher efficiency.

  According to the acidic waste liquid treatment apparatus 3 of the present embodiment, the waste water treatment is completed in the same treatment system by returning the desalted water to the cation exchange resin and recontacting the liquid with the cation exchange resin. Therefore, the operating rate of the treatment facility is improved, and the acidic waste liquid can be treated with higher efficiency.

(Fourth embodiment)
FIG. 7 is a schematic configuration diagram showing an embodiment of an apparatus for treating acidic waste liquid containing metal ions according to the present invention. As shown in FIG. 7, the acidic waste liquid treatment apparatus 4 of the present embodiment is
An acidic waste liquid storage tank 10 for storing an acidic waste liquid containing metal ions, an adsorption tower 20 and 23 having a cation exchange resin to which the acidic waste liquid is supplied from the acidic waste liquid storage tank 10 and adsorbs the metal ions, and the cation Regenerative chemical liquid introduction means 40, 41 for desorbing the metal ions adsorbed on the exchange resin from the cation exchange resin to obtain a desorbed liquid containing the metal ions into the adsorption tower; Alkali adding means 70 and 71 for adding alkali to the desorbing liquid and the desorbing liquid are introduced to obtain concentrated water in which the concentration of the metal ions is higher than the concentration of the metal ions in the desorbing liquid. An electrodialysis apparatus 50, a neutralized coagulation sedimentation facility 60 that is supplied with the concentrated water and neutralizes the coagulated sediment, and is obtained together with the concentrated water. Comprising a demineralized water in which the concentration of the metal ions was lower than degrees, and return pipe 52 for returning to the adsorption tower, the.

  In the acidic waste liquid treatment apparatus of the fourth embodiment, the acidic waste liquid treatment apparatus of the (third embodiment) has a plurality of adsorption towers. Hereinafter, although the acidic waste liquid processing apparatus of 4th Embodiment is demonstrated, description is abbreviate | omitted about the point which is common in the acidic waste liquid processing apparatus of the said 1st-3rd embodiment.

  The acidic waste liquid treatment apparatus 4 of this embodiment includes a first adsorption tower 20 and a second adsorption tower 23. Since the acidic waste liquid treatment apparatus 4 has a plurality of adsorption towers, the acidic waste liquid can be treated more efficiently by alternately operating these adsorption towers.

FIG. 8 is a schematic diagram showing a state in which the first adsorption tower 20 and the second adsorption tower 23 are alternately operated.
A pipe 13 is connected to the second adsorption tower 23, and acidic waste liquid is introduced from the acidic waste liquid storage tank via the pipe 13. Thereby, in the 2nd adsorption tower 23, the metal ion contained in acidic waste liquid adsorb | sucks to a cation exchange resin (process A of FIG. 1).
On the other hand, a regenerative chemical solution introduction pipe 41 is connected to the first adsorption tower 20, and a regenerative chemical solution is introduced from the regenerative chemical solution storage tank 40. An acidic waste liquid is introduced into the first adsorption tower 20 in advance, and metal ions contained in the acidic waste liquid are adsorbed on the cation exchange resin of the first adsorption tower 20. When the regenerated chemical solution is introduced into the first adsorption tower 20, the metal ions adsorbed on the cation exchange resin are desorbed from the cation exchange resin (step B in FIG. 1).

  Thus, in the acidic waste liquid processing apparatus 4 of the present embodiment, the process A and the process B can be simultaneously performed by one processing apparatus, and the acidic waste liquid can be more efficiently processed.

  Hereinafter, the present invention will be specifically described with reference to test examples. However, the present invention is not limited to these.

(1) Preparation of Mineral Wastewater Model Liquid As a mineral wastewater model liquid, a liquid reproducing the composition of a typical mineral wastewater was prepared with the composition shown in Table 2 below.

(2) Cation adsorbent test Using the mineral wastewater model liquid prepared in (1) above, the mineral wastewater model liquid was brought into contact with the cation exchange resin through a cation exchange column having a cation exchange resin. The cation exchange resin is a strongly acidic cation exchange resin having a sulfonic acid group as an exchange group.

The processing conditions are as follows.
・ Cation exchange resin: (Diaion PK216, Mitsubishi Chemical)
・ Adsorption test Flow rate: SV = 5
Desorption test Flow direction: Downflow Desorption solution: sulfuric acid aqueous solution (pH 0.25)
Flow rate: SV = 5
Evaluation method Analytical method: ICP analysis Quantitative metal: Na, Fe, Cu, Zn, Al, Ca, Mg

  The mineral wastewater model liquid is brought into contact with the cation exchange resin, and the metal ions in the mineral wastewater model liquid are adsorbed onto the cation exchange resin (adsorption). Desorption (desorption) of metal ions adsorbed on the exchange resin from the cation exchange resin was repeated until adsorption and desorption were stabilized.

  In each treatment of adsorption and desorption, the concentration of each metal ion in the column effluent after passing through the cation exchange column was quantified. Table 3 shows the composition of each metal ion in the desorbed liquid when stable adsorption and desorption are performed.

The concentration ratio of metal ions in the cation adsorbent test was calculated by the following formula.
Total metal ion concentration in desorbed liquid [mg / L] ÷ Total metal ion concentration in mineral wastewater model liquid [mg / L] = 2037 ÷ 531 ≒ 3.8
From the above results, it was shown that the metal ions in the mineral wastewater model liquid can be concentrated up to about 3.8 times by introducing the mineral wastewater model liquid into the cation exchange column.

(3) Electrodialysis test simulation It was assumed that the results of the above (2) cation adsorbent test were obtained and prepared as a desorbed liquid model solution with the composition shown in Table 4 below.

  It was assumed that a liquid obtained by adding an alkali to the desorption liquid model liquid was prepared as a desorption liquid model liquid after addition of the alkali with the composition shown in Table 5 below. The pH of the desorbed liquid model solution after alkali addition was set to 2.0.

A simulation was performed in which the detachment liquid model solution after the alkali addition was electrodialyzed using two electrodialyzers according to the processing flow shown in FIG.
The simulation conditions for electrodialysis are as follows.
Desorption liquid flow rate: 3800 L / h
Recovery rate (flow rate of demineralized water relative to the desorbed liquid): 80% or more Desalination rate: 90% or more Electrodialyzer (1)
Membrane logarithm: 260
Membrane area: 0.425 m ² / sheet DC: 130 A × 150 V = 19.5 kW
Electrodialysis machine (2)
Membrane logarithm: 260
Membrane area: 0.425 m ² / sheet DC: 40 A × 150 V = 6.0 kW

In FIG. 9, the predicted value of the material balance in an electrodialysis test is shown.
From the above results, the liquid volume (Q) is scaled down from 3800 L / h to 582 L / h by electrodialyzing the desorbed liquid model solution after addition of alkali to obtain concentrated water by electrodialysis test simulation. Rukoto has been shown. Moreover, the concentration rate of the metal ion by electrodialysis simulation was computed by the following formula.
Total metal ion concentration in concentrated water [mg / L] ÷ Total metal ion concentration in desorbed liquid model solution after addition of alkali [mg / L] = 24816 ÷ 4003 ≒ 6.2
From the above results, it was shown that the metal ions in the desorbed solution after addition of alkali can be concentrated to about 6 times by electrodialyzing the desorbed solution model solution after addition of alkali.

(4) Simulation of the balance of the entire mineral wastewater treatment Based on the results obtained in the above (3) electrodialysis test simulation, the material balance of the entire treatment method of the mineral wastewater was simulated.
In FIG. 10, the predicted value of the material balance of the whole processing method of mineral wastewater is shown.

The concentration ratio of metal ions was calculated by the following formula, combining the results of the above (2) cation adsorbent test and the above (3) electrodialysis test simulation.
Total metal ion concentration in concentrated water [mg / L] ÷ Total metal ion concentration in mineral wastewater model liquid [mg / L] = 24816 ÷ 531 ≒ 46.7
From the above results, it was shown that the metal ions of the mineral wastewater model liquid can be concentrated approximately 47 times by treating the mineral wastewater model liquid with a cation exchange column and performing electrodialysis.

Moreover, the amount of treated water used for neutralization aggregation precipitation was calculated by the following formula.
Concentrated water treatment volume [L / h] ÷ Mineral wastewater model liquid treatment water volume [L / h] = 582 ÷ 20000 ≒ 1/34
From the above results, it is possible to significantly reduce the amount of treated water used for neutralization coagulation precipitation to about 1/34 by treating the mineral wastewater model liquid with a cation exchange column and performing electrodialysis. This indicates that the amount of neutralizing agent used for neutralization coagulation precipitation can be greatly reduced.

DESCRIPTION OF SYMBOLS 1, 2, 3, 4 ... Acid waste liquid processing apparatus, 10 ... Acid waste liquid storage tank, 11 ... Dust remover, 12 ... Pipe, 13 ... Pipe, 20 ... Adsorption tower, 1st adsorption tower, 21 ... Pipe, 22 ... Piping, 23 ... second adsorption tower, 30 ... desorbed liquid storage tank, 31 ... piping, 40 ... regenerated chemical liquid storage tank, 41 ... regenerated chemical liquid introduction pipe, 50 ... electrodialyzer, 51 ... pipe, 52 ... return pipe, 60 ... neutralization coagulation sedimentation equipment, 61 ... piping, 70 ... alkali storage tank, 71 ... alkali introduction pipe

Claims (4)

Contacting the acidic waste liquid containing metal ions with a cation adsorbent to adsorb the metal ions to the cation adsorbent;
Desorbing the metal ions adsorbed on the cation adsorbent from the cation adsorbent to obtain a desorbed liquid containing the metal ions;
A step B2 of adding an alkali to the desorption liquid;
Introducing the desorption solution into an electrodialysis apparatus having an anion exchange membrane and a cation exchange membrane to obtain concentrated water having a concentration of the metal ions higher than the concentration of the metal ions in the desorption solution; C
Step D for neutralizing and coagulating sedimentation of the concentrated water;
The processing method of the acidic waste liquid containing the metal ion characterized by having. A step E of contacting deionized water obtained together with the concentrated water and having a concentration of the metal ions lower than the concentration of the metal ions in the desorbed liquid with the cation adsorbent. The processing method of the acidic waste liquid containing the metal ion of Claim 1 . An acidic waste liquid storage tank for storing an acidic waste liquid containing metal ions;
An adsorption tower having a cation adsorbent to which the acidic waste liquid is supplied from the acidic waste liquid storage tank and the metal ions are adsorbed;
Regenerative chemical liquid introduction means for desorbing the metal ions adsorbed on the cation adsorbent from the cation adsorbent to obtain a desorbed liquid containing the metal ions into the adsorption tower;
Alkali adding means for adding alkali to the desorbing solution;
An electrodialysis apparatus that obtains concentrated water into which the desorbed liquid has been introduced and the concentration of the metal ions is higher than the concentration of the metal ions in the desorbed liquid;
An apparatus for treating an acidic waste liquid containing metal ions, comprising: a neutralization coagulation sedimentation facility that is supplied with the concentrated water and neutralizes coagulation sedimentation treatment of the concentrated water. A return pipe for returning deionized water obtained together with the concentrated water and having a concentration of the metal ions lower than the concentration of the metal ions in the desorbed liquid to the adsorption tower. An apparatus for treating acidic waste liquid containing the metal ion according to 3 .

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