JP2008006403A - Method for recovering phosphorus and regenerating adsorbent for phoshorus in waste water treatment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adsorbing and regenerating method capable of improving an adsorption and recovery efficiency of phosphorus and a regeneration efficiency of an adsorbent in waste water treatment for removing phosphorous in waste water using the adsorbent. <P>SOLUTION: In a method for treating phosphorus-containing waste water by using the adsorbent consisting of specific compound metal hydroxide to remove a phosphorus component in phosphorus-containing waste water, the phosphorus component is adsorbed on the compound metal hydroxide and the desorption of the adsorbed phosphoric acid and the regeneration of the used adsorbent are performed by bringing the compound metal hydroxide into contact with a specific alkaline aqueous solution, washing the resulting compound metal hydroxide with water and further bringing the washed compound metal hydroxide into contact with an aqueous solution of specific alkaline-earth metal salt. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  With regard to wastewater treatment for human waste, sewage, food processing wastewater and factory wastewater, livestock manure, etc., the phosphorus desorption recovery efficiency and the adsorbent regeneration efficiency are improved in wastewater treatment that removes phosphorus in the wastewater with an adsorbent. The present invention relates to a desorption regeneration method that can be performed.

  In recent years, organic substances, nitrogen, phosphorus, etc. contained in large quantities in rivers, various industrial wastewater or domestic wastewater, are cited as factors of eutrophication that leads to water pollution of lakes and marshes that promote the generation of algae and red tide in the nearby sea. It has been. Establishing advanced water treatment technology capable of removing nitrogen and phosphorus from high to low concentrations, which are said to be 0.15ppm and 0.02ppm of phosphorus as the limiting concentrations of nitrogen and phosphorus that cause eutrophication. Is strongly desired.

  Methods for removing the phosphorus component in the wastewater are roughly divided into a biological treatment method and a physicochemical treatment method. Among the physicochemical treatment methods, a coagulation precipitation method is generally used in which a phosphorus component is removed as a poorly soluble phosphate using a flocculant from the viewpoint of economy, treatment efficiency, and the like. However, there are issues that should be studied in the future, such as spillage of salts derived from the flocculant due to the addition of flocculant, problems of sludge treatment and phosphorus recovery / reuse, and insufficient phosphorus removal in low concentrations. Can be mentioned.

As a method other than the coagulation precipitation method, an adsorption treatment method of a phosphorus component using a phosphorus adsorbent (see, for example, Patent Document 1) has been attempted. In the adsorption method, aluminum hydroxide gel, magnesium oxide, titanium oxide-activated carbon composite agent, zirconium oxide-activated carbon composite agent, volcanic ash soil, etc. and those modified soil are used as the phosphorus adsorbent, A regeneration method for improving the number of times the adsorbent is used and a desorption method for desorbing and collecting adsorbed phosphorus with high efficiency have been problems in practical use.
In order to solve this problem, a method for regenerating a phosphoric acid desorbent relating to a phosphorus component adsorbent of a composite metal hydroxide has also been proposed (see, for example, Patent Document 2), but higher efficiency has been demanded. .

Japanese Patent No. 3131183 JP-A-2005-305343

  An object of the present invention is to provide a desorption / regeneration method capable of improving the desorption / recovery efficiency of the phosphorus component and the regeneration efficiency of the adsorbent in the wastewater treatment in which the phosphorus component in the wastewater is removed by the adsorbent.

  The inventors of the present invention have reached the present invention as a result of further intensive studies in view of the above prior art.

That is, the object of the present invention is to
In the processing method of the phosphorus containing wastewater which removes the phosphorus component in the phosphorus containing wastewater using the composite metal hydroxide represented by the following chemical composition formula (1) as an adsorbent,
After the phosphorus component is adsorbed on the composite metal hydroxide, the subsequent desorption of the adsorbed phosphorus component and the regeneration treatment of the adsorbent are performed by sequentially passing the following steps (A) and (B). This can be achieved by a method for desorbing and regenerating the adsorbent.
Step (A): A step of bringing the composite metal hydroxide having adsorbed the phosphorus component into contact with an alkaline aqueous solution in which an alkali metal salt having a purity of 99% or more is dissolved, excluding carbonate.
Step (B): A step of washing the composite metal hydroxide after passing through the step (A) with an aqueous alkaline earth metal salt solution excluding carbonate after washing with water.
[Chemical 1]
M _1-x ²⁺ M _x ³⁺ (OH ⁻ ) _{2 + xy} (A ⁿ⁻ ) _{y / n} (1)
( ^Wherein M ²⁺ represents at least one divalent metal ion selected from the group consisting of Mg ²⁺ , Ni ²⁺ , Zn ²⁺ , Fe ²⁺ , Ca ²⁺ and Cu ²⁺ , and M ³⁺ represents Al ³⁺ and Fe ^3+. At least one trivalent metal ion selected from the group consisting of: An ⁿ⁻ represents an n-valent anion, 0.1 ≦ x ≦ 0.5, and 0.1 ≦ y ≦ 0.5 And n is 1 or 2.)

  ADVANTAGE OF THE INVENTION According to this invention, the desorption reproduction | regeneration method which can improve the desorption collection | recovery efficiency of a phosphorus component, and the regeneration efficiency of an adsorption agent can be provided in the waste_water | drain process which removes the phosphorus component in waste_water | drain with an adsorption agent.

Hereinafter, the present invention will be described in detail.
In the wastewater treatment in which the phosphorus component, which is a eutrophication product in the wastewater, is removed by the phosphorus component adsorbent, the desorption of phosphorus is performed during the subsequent desorption of the adsorbed phosphorus component and the regeneration treatment of the adsorbent. This improves the recovery efficiency and the adsorbent regeneration efficiency.

Here, the phosphorus component adsorbent in the present invention is
Chemical composition formula (1): M _1-x ²⁺ M _x ³⁺ (OH ⁻ ) _{2 + xy} (A ⁿ⁻ ) _{y / n} (1)
( ^Wherein M ²⁺ represents at least one divalent metal ion selected from the group consisting of Mg ²⁺ , Ni ²⁺ , Zn ²⁺ , Fe ²⁺ , Ca ²⁺ and Cu ²⁺ , and M ³⁺ represents Al ³⁺ and Fe ^3+. At least one trivalent metal ion selected from the group consisting of: An ⁿ⁻ represents an n-valent anion, 0.1 ≦ x ≦ 0.5, and 0.1 ≦ y ≦ 0.5 And n is 1 or 2.), and specifically, for example, can have the following composition.
[Chemical 2]
Mg ²⁺ _0.665 Fe ³⁺ _0.335 OH ⁻ _2.099 Cl ⁻ _0.124 (CO ₃ ²⁻ ) _0.056
[Chemical formula 3]
^{_{Mg 2+ 0.683 Al 3+ 0.317 OH -}} 2.033 Cl - 0.238 (CO 3 2-) 0.023

The adsorbent having an average particle diameter of 0.01 to 500 μm can be used as the adsorbent-supported polymer molded article with the above composite metal hydroxide as it is or supported on a polymer.
As the polymer for supporting, an aramid resin, an acrylic resin, a vinyl alcohol resin, a cellulose resin, etc. that can be porously formed by wet coagulation can be used, but within the scope of the object of the present invention. Any polymer may be used as long as it is. Further, the shape of the adsorbent and the adsorbent-supported polymer molded body is not limited to a circular shape, for example, and can take various shapes.

In the present invention, the phosphorus component in the phosphorus waste water is adsorbed to the adsorbent, and then the phosphorus component is desorbed from the adsorbent. The phosphorus component desorbed liquid from the adsorbent is excluded from carbonate. An alkaline aqueous solution in which an alkali metal salt is dissolved is used. Here, preferable alkali metal salts include sodium hydroxide, potassium hydroxide, sodium chloride, potassium chloride, sodium fluoride, potassium fluoride, sodium bromide, potassium bromide, sodium sulfate, potassium sulfate, sodium sulfite, and sulfurous acid. Potassium etc. are mentioned, More preferably, sodium chloride is mentioned.
In order to increase the phosphorus component desorption recovery rate, the purity of the alkali metal salt needs to be 99% or more.

  The desorption operation can be easily performed by bringing the adsorbent into contact with an alkaline aqueous solution. Any temperature and pressure at the time of contact can be adopted as long as the aqueous solution maintains a liquid phase, but from the viewpoint of process stability, cost, etc., 10 to 40 ° C., 0.1 to 0 What is necessary is just to set to about 5 MPa.

Further, the contact time may be set in any way as long as the phosphorus component can be desorbed. For example, when the contact is performed in a palindromic manner, the contact time is about 0.5 to 15 hours when the contact is performed continuously. Is about 0.5 to 4 hours. Examples of the contact method include, but are not particularly limited to, a method of immersing the adsorbent in the alkaline aqueous solution, a method of introducing the alkaline aqueous solution into the tower filled with the adsorbent, and the like.
The pH of the alkaline aqueous solution is preferably 11 or higher.

  In addition, it is preferable to collect | recover the alkaline aqueous solution after making it contact with adsorption agent, and to adjust so that pH may be in the range of 8-13. Although the pH adjuster is not particularly defined, hydrochloric acid or sulfuric acid can be used as the acid, but hydrochloric acid is preferred. Sodium hydroxide or potassium hydroxide can be used as the alkali. After the adjustment, ammonium ions and magnesium ions are further added to remove the phosphorus component as a precipitate (magnesium ammonium phosphate), and the alkaline aqueous solution is used as the alkaline aqueous solution in the above step (A) or the steps described later. It can also be reused as the alkaline earth metal salt aqueous solution of (B). Further, after adjusting the recovered alkaline aqueous solution so that the pH is in the range of 4.5 to 13.5, further adding calcium ions to remove the phosphorus component as a precipitate (hydroxyapatite), Since it contains magnesium ion as the alkaline aqueous solution in the step (A), it can be reused as the alkaline earth metal salt aqueous solution in the later-described step (B).

In the present invention, after the phosphorus component adsorbent is brought into contact with an alkaline aqueous solution and subjected to desorption treatment, the adsorbent is washed with water and brought into contact with an alkaline earth metal salt aqueous solution in order to improve the adsorbent regeneration rate. Perform playback processing.
Here, the washing with water may be performed under any conditions as long as the alkaline aqueous solution existing inside or on the surface of the adsorbent can be removed. For example, the alkaline aqueous solution may be removed by washing with water vapor.

Next, the alkaline earth metal salt aqueous solution for performing the regeneration treatment is preferably an aqueous solution of magnesium chloride, calcium chloride, magnesium sulfate, magnesium bromide, calcium bromide or the like, more preferably magnesium chloride and magnesium sulfate aqueous solution. More preferably, magnesium chloride is used.
There is no restriction | limiting with respect to purity about an alkaline-earth metal salt, For example, the thing of the purity specification 95% currently sold as an industrial salt can be used.

  The regeneration operation can be easily performed by bringing the adsorbent after washing with water into contact with the alkaline earth metal salt aqueous solution. Any temperature and pressure at the time of contact can be adopted as long as the aqueous solution maintains a liquid phase, but from the viewpoint of process stability, cost, etc., 10 to 40 ° C., 0.1 to 0. What is necessary is just to set to about 5 MPa.

  The contact time may be set as long as the adsorbent can be regenerated. For example, when the contact is performed in a palindromic manner, the contact time is about 0.5 to 20 hours. Is about 0.5 to 5 hours. Examples of the contact method include a method of immersing the adsorbent in the alkaline earth metal salt aqueous solution, a method of charging the alkaline earth metal salt aqueous solution into the tower filled with the adsorbent, and the like. It is not limited.

Further, the phosphorus component in the phosphorus adsorbent is recovered as a water-soluble phosphorus component by desorption of the phosphorus component from the adsorbent with an alkaline earth metal salt aqueous solution and regeneration treatment of the adsorbent.
Therefore, as long as the alkaline aqueous solution is used without being exchanged, the adsorption / desorption operation is a concentration operation of the phosphorus component, that is, the concentration of the phosphorus component in the alkaline aqueous solution can be made much higher than the drainage liquid, and the concentration can be increased. Since it can be removed from the aqueous solution containing the phosphorus component, it can be efficiently recovered.

  In addition, the alkaline earth metal salt aqueous solution is repeatedly used as it is, and when the phosphorus component concentration becomes a certain level or more, the same operation as the removal of the phosphorus component from the alkaline earth metal salt aqueous solution is performed, and the alkaline earth metal again. It can be reused as a metal salt aqueous solution.

  Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.

[Example 1]
Mg-Al-Cl type hydrotalcite adsorbent with an average particle size of 10 μm (Tonda Pharmaceutical Co., Ltd., TPEX standard product) is supported on a meta-aramid polymer (manufactured by Teijin Techno Products Co., Ltd., CONEX powder). A spherical molded body having a diameter of 0.5 to 1.0 mm (hydrotalcite: meta-aramid polymer = 90 wt%: 10 wt%), and a hydrotalcite weight of 15 g, a 1 L solution having a phosphorus concentration of 175 mg / L And was stirred for 4 hours at 300 rpm using a propeller blade to adsorb the phosphorus component. The amount of the adsorbed phosphorus component was 9.4 mg per 1 g of hydrotalcite.
The amount of the phosphorus component adsorbed on the hydrotalcite adsorbent is calculated using the value obtained by quantifying the phosphorus concentration contained in the solution after adsorption using the molybdenum blue method.

Next, 2.65 g of the adsorbent that has adsorbed phosphorus is hydrotalcite by weight into an alkaline earth metal salt aqueous solution of 34 g of sodium chloride (purity 99% or more), 1 g of sodium hydroxide, and 100 g of water for 150 minutes. Stir.
The phosphorus concentration in the aqueous solution was measured at regular intervals, and the phosphorus desorption rate was calculated based on the following formula. The results are shown in FIG.
[Equation 1]
Phosphorus desorption rate = phosphorus concentration in alkaline earth metal salt aqueous solution / phosphorus adsorption amount (= 9.4 mg)

[Example 2]
A spherical molded body molded in the same manner as in Example 1 was immersed in 100 mL of a solution having a hydrotalcite weight of 2.65 g and a phosphorus concentration of 958 mg / L, and stirred at 300 rpm for 4 hours using a propeller blade. The phosphorus component was adsorbed. The amount of phosphorus adsorbed was 34.7 mg per 1 g of hydrotalcite.

Next, 2.65 g of the adsorbent that has adsorbed phosphorus in terms of hydrotalcite weight is charged into an alkaline earth metal salt aqueous solution of 34 g of sodium chloride (purity 99% or more), 1 g of sodium hydroxide, and 100 g of water for 120 minutes. Stir.
The adsorbent after 120 minutes was taken out and washed with water, and then poured into an alkaline earth metal salt aqueous solution of 74.9 g of magnesium chloride hexahydrate and 100 g of water and stirred for 120 minutes.

  Next, the adsorbent after 120 minutes was taken out, washed with water, immersed in 100 mL of a solution having a phosphorus concentration of 958 mg / L, and stirred at 300 rpm for 4 hours using a propeller blade to adsorb the phosphorus component. The amount of phosphorus adsorbed was 33.2 mg per 1 g of hydrotalcite.

[Comparative Example 1]
Phosphorus-adsorbed adsorbent that adsorbs phosphorus in the same manner as in Example 1 was added in an amount of 2.65 g in terms of hydrotalcite weight, 34 g of industrial sodium chloride (purity 98.6%), 1 g of sodium hydroxide, The mixture was put into 100 g of an alkaline earth metal salt aqueous solution and stirred for 150 minutes.
The phosphorus concentration in the aqueous solution was measured at regular intervals, and the phosphorus desorption rate was calculated based on the following formula. The results are shown in FIG.
[Equation 2]
Phosphorus desorption rate = phosphorus concentration in alkaline earth metal salt aqueous solution / phosphorus adsorption amount (= 9.4 mg)

[Comparative Example 2]
Phosphorus-adsorbed adsorbent adsorbing phosphorus in the same manner as in Example 1 was added in an amount of 2.65 g in terms of hydrotalcite weight, industrial sodium chloride (purity 98.6%) 40 g, sodium hydroxide 1 g, The mixture was poured into an alkaline earth metal salt aqueous solution of 100 g of water and stirred for 150 minutes.
The phosphorus concentration in the aqueous solution was measured at regular intervals, and the phosphorus desorption rate was calculated based on the following formula. The results are shown in FIG.
[Equation 3]
Phosphorus desorption rate = phosphorus concentration in alkaline earth metal salt aqueous solution / phosphorus adsorption amount (= 9.4 mg)

[Comparative Example 3]
Phosphorus-adsorbed adsorbent adsorbing phosphorus in the same manner as in Example 1 was added in an amount of 2.65 g in terms of hydrotalcite weight, 34 g of industrial sodium chloride (purity 97.8%), 1 g of sodium hydroxide, The mixture was put into 100 g of an alkaline earth metal salt aqueous solution and stirred for 150 minutes.
The phosphorus concentration in the aqueous solution was measured at regular intervals, and the phosphorus desorption rate was calculated based on the following formula. The results are shown in FIG.
[Equation 4]
Phosphorus desorption rate = phosphorus concentration in alkaline earth metal salt aqueous solution / phosphorus adsorption amount (= 9.4 mg)

[Comparative Example 4]
Phosphorus-adsorbed adsorbent adsorbing phosphorus in the same manner as in Example 1 was added to an amount of 2.65 g in terms of hydrotalcite weight, 40 g of industrial sodium chloride (purity 97.8%), 1 g of sodium hydroxide, The mixture was put into 100 g of an alkaline earth metal salt aqueous solution and stirred for 150 minutes.
The phosphorus concentration in the aqueous solution was measured at regular intervals, and the phosphorus desorption rate was calculated based on the following formula. The results are shown in FIG.
[Equation 5]
Phosphorus desorption rate = phosphorus concentration in alkaline earth metal salt aqueous solution / phosphorus adsorption amount (= 9.4 mg)

[Comparative Example 5]
In the same manner as in Example 2, the addition into the alkaline earth metal salt aqueous solution was omitted, the sample was immersed in 100 mL of a phosphorus concentration of 958 mg / L, and stirred at 300 rpm for 4 hours using a propeller blade. The amount of phosphorus adsorbed was 24.2 mg / g hydrotalcite.

  The present invention is a desorption / regeneration method capable of improving phosphorus desorption / recovery efficiency and adsorbent regeneration efficiency in wastewater treatment for removing phosphorus in wastewater by using an adsorbent. Since the adsorbent can be used repeatedly by improving the regeneration efficiency of the adsorbent, it is possible to reduce the amount of new use of the expensive adsorbent, that is, to reduce the cost.

It is a graph of the desorption performance evaluation of the desorption reproduction | regeneration method by this invention, and comparative evaluation.

Claims (4)

In the processing method of the phosphorus containing wastewater which removes the phosphorus component in the phosphorus containing wastewater using the composite metal hydroxide represented by the following chemical composition formula (1) as an adsorbent,
After the phosphorus component is adsorbed on the composite metal hydroxide, the subsequent desorption of the adsorbed phosphorus component and the regeneration treatment of the adsorbent are performed by sequentially passing the following steps (A) and (B). A method for desorbing and regenerating an adsorbent.
Step (A): A step of bringing the composite metal hydroxide having adsorbed the phosphorus component into contact with an alkaline aqueous solution in which an alkali metal salt having a purity of 99% or more is dissolved, excluding carbonate.
Step (B): A step of washing the composite metal hydroxide after passing through the step (A) with an aqueous alkaline earth metal salt solution excluding carbonate after washing with water.
[Chemical 1]
M _1-x ²⁺ M _x ³⁺ (OH ⁻ ) _{2 + xy} (A ⁿ⁻ ) _{y / n} (1)
( ^Wherein M ²⁺ represents at least one divalent metal ion selected from the group consisting of Mg ²⁺ , Ni ²⁺ , Zn ²⁺ , Fe ²⁺ , Ca ²⁺ and Cu ²⁺ , and M ³⁺ represents Al ³⁺ and Fe ^3+. At least one trivalent metal ion selected from the group consisting of: An ⁿ⁻ represents an n-valent anion, 0.1 ≦ x ≦ 0.5, and 0.1 ≦ y ≦ 0.5 And n is 1 or 2.)   The desorption regeneration method according to claim 1, wherein the pH of the alkaline aqueous solution is 11 or more.   In step (A), after recovering the alkaline aqueous solution after contact with the composite metal hydroxide and adjusting the pH to be in the range of 8 to 11, ammonium ions and magnesium ions are further added to add phosphorus. The desorption regeneration method of Claim 1 which removes a component as a deposit and recycles as the alkaline aqueous solution of a process (A) or the alkaline-earth metal salt aqueous solution of a process (B).   In step (A), after recovering the alkaline aqueous solution after contact with the composite metal hydroxide and adjusting the pH to be in the range of 4.5 to 13.5, calcium ions are further added. The desorption regeneration method according to claim 1, wherein the phosphorus component is removed as a precipitate and reused as the alkaline aqueous solution in step (A) or the alkaline earth metal salt aqueous solution in step (B).

Images