JP2002292372A - Method for producing dephosphorizing agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a dephosphorizing agent capable of eluting calcium as a dephosphorizing agent, free from coagulation sedimentation, and capable of effectively removing phosphorous from phosphorous- containing water without trouble. SOLUTION: Water is added to a calcium compound, comprising wollastonite or a cement material and having a particle size of 2-100 mm. Then the mixture is shaped before being subjected to carbonation treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a phosphorus removing material for removing phosphorus from phosphorus-containing water.

[0002]

2. Description of the Related Art Conventionally, as a method for removing phosphorus from phosphorus-containing water, there are a biological treatment method and a physicochemical treatment method. The biological treatment method is a treatment method in which bacteria that take up phosphorus excessively are proliferated in activated sludge, thereby removing sludge from the system while phosphorus is taken up excessively.
This method has the drawback of releasing phosphorus again when sludge removed outside the system is left in an anaerobic state for a long time,
It is necessary to pay attention to the phosphorus concentration in the return water from the sludge concentration system, and it is necessary to perform rapid concentration using a sludge concentrator and coagulation treatment of the re-released phosphorus.

On the other hand, the physicochemical treatment methods are further classified into an electrolysis method, a coagulation precipitation method, an adsorption removal method, a crystallization dephosphorization method and the like. The electrolysis method is a method in which an electrode plate made of aluminum, iron, or the like is placed in phosphorus-containing water, and an electric current is applied to remove phosphorus in the phosphorus-containing water as insoluble aluminum phosphate or iron phosphate. This method has safety issues such as the use of electricity and generation of hydrogen, and secondary waste disposal due to the large amount of sludge generated.

In the coagulation precipitation method, an aluminum salt such as aluminum sulfate or a metal salt coagulant such as an iron salt such as ferrous sulfate or ferric chloride is added to phosphorus-containing water to make the phosphorus in the phosphorus-containing water insoluble. By removing the compound of formula In this method, the amount of the metal salt for removing phosphorus stably is required to be three times or more in molar ratio with respect to the amount of existing phosphorus, and there is a problem that a large amount of coagulated sludge is generated.

[0005] The adsorption removal method is a method in which an adsorbent having fine pores such as activated carbon or zeolite is added to phosphorus-containing water, and phosphorus in the phosphorus-containing water is removed by adsorbing the fine pores mainly in a phosphoric acid form. . In this method, there are problems such as poor phosphorus removal efficiency due to low adsorption capacity, and a high unit price of the adsorbent.

In the crystallization dephosphorization method, a crystal comprising calcium phosphate or the like is added to phosphorus-containing water as a seed crystal to precipitate phosphorus in the phosphorus-containing water as an insoluble substance such as hydroxyapatite on the seed crystal. This is a method for removing phosphorus by using the method. This is a method in which much research and development has been carried out because of the advantages such as extremely low amount of sludge generation, safety and economy.

In the case of producing a dephosphorized material by a crystallization dephosphorization method from a calcium material, it is generally necessary to shape the material since the material is often a powder. If not shaped,
This is because the calcium material itself becomes sludge. Shaping,
In order to maintain the shape, it is easy to harden by mixing a cement material or gypsum with water. However, in these methods, the amount of calcium eluted is too large, so that the generally required 1p
When used for water to be treated having a phosphorus concentration of pm or more, sludge is likely to be generated. Therefore, there has been proposed a crystallization method in which the amount of calcium eluted is controlled to be constant by autoclaving the cement material to obtain calcium silicate hydrate (Japanese Patent Application Laid-Open No. 62-183898). But,
In this method, the range of the amount of calcium eluted from calcium silicate hydrate is limited, so that it has been difficult to efficiently perform crystallization dephosphorization according to the phosphorus concentration of the water to be treated.

To solve the problem, Japanese Patent Laid-Open No. 10-3 is disclosed.
No. 4167 discloses that a dephosphorizing material mainly composed of calcium silicate hydrate is used as a seed crystal, which is filled or fluidized in a reaction vessel, and that phosphorus-containing water is passed and retained in the reaction vessel. In addition, a method has been proposed in which phosphorus is crystallized and removed from phosphorus-containing water as hydroxyapatite, and calcium chloride is added as a calcium source.

[0009]

However, in this method, there are problems that it is troublesome and that the amount of calcium chloride to be added must be controlled.

[0010] In view of the above-mentioned conventional problems, the present invention has a calcium-eluting property suitable as a dephosphorizing material, has no formation of coagulated sediment, and can be effectively removed from phosphorus-containing water without trouble. An object of the present invention is to provide a method for producing a phosphorus-removing material capable of removing phosphorus.

[0011]

The method for producing a phosphorus-removing material of the present invention comprises subjecting a calcium compound to a carbonation treatment.

Hereinafter, the present invention will be described in more detail. The calcium compound in the present invention is not particularly limited, and calcium silicate compounds such as wollastonite, tobermorite, zonotolite, hillebranite, and aphilite; Cement materials comprising cement or hydrates thereof, such as ordinary Portland cement and early-strength Portland cement; gypsum; ionic compounds such as calcium carbonate and calcium phosphate; and wastes thereof. The calcium compound preferably retains its shape when added to water.

In particular, it is preferable to use wollastonite as a calcium compound for the water to be treated having a phosphorus concentration of 1 to 50 ppm, more preferably about 5 to 30 ppm. . Wollastonite is hardened by the carbonation treatment, functions as a binder that hardly causes precipitation even at a high phosphorus concentration, and can efficiently perform crystallization dephosphorization.

For the water to be treated having a phosphorus concentration of 0.1 to 25 ppm, more preferably about 0.5 to 10 ppm, a cement material is used as a calcium compound. Is preferred. The cement material refers to an inorganic substance and a hydrate thereof which show curability when kneaded with water, and more preferably a portland cement, a mixed portland cement or a hydrate thereof, a concrete waste material, or the like. In general, a cement material is a material suitable for shaping, but cannot be used for the crystallization dephosphorization method due to precipitation in water to be treated having a high phosphorus concentration. The amount of calcium eluted.

[0015] The particle size of the calcium compound is defined in claim 4
As described in above, it is preferably from 2 to 100 mm, more preferably from 5 to 50 mm, and still more preferably from 10 to 30 mm. If the particle size of the calcium compound is too small, coagulation and sedimentation is likely to occur, and the surface area required for the crystallization reaction is sufficiently ensured, but the handling property is poor and becomes a suspended substance when added to phosphorus-containing water, This is because they may be lost together with the water stream, and if too large, it is difficult to secure a surface area necessary for the crystallization reaction, resulting in a decrease in dephosphorization efficiency.

In the method for producing a dephosphorizing material of the present invention, the calcium compound is subjected to a carbonation treatment.

The above-mentioned carbonation treatment means a treatment in which an alkali component in a calcium compound is carbonated. The carbonation treatment method is not particularly limited, and includes, for example, a method of treating with gas or supercritical carbon dioxide under pressurized heating.

The carbon dioxide partial pressure (hereinafter referred to as “treatment pressure”) in the above carbonation treatment is not particularly limited.
The pressure is preferably 0.01 to 15 MPa, more preferably 0.2 to 10 MPa. If the treatment pressure is too low, the carbonation treatment reaction does not sufficiently occur, and when the obtained dephosphorizing material is added to phosphorus-containing water, the alkaline component in the calcium compound is excessively eluted and the pH increases. In addition, a large amount of coagulation and sedimentation may be generated, and a large amount of sludge may be generated. On the other hand, even if the treatment pressure is too high, the carbonation treatment efficiency does not change significantly, and on the contrary, a large amount of energy is required, which is not preferable from the viewpoint of industrial productivity and enlargement of equipment.

The atmosphere temperature (hereinafter referred to as “treatment temperature”) in the above carbonation treatment is not particularly limited.
° C or higher, more preferably 50 to 2 ° C.
00 ° C. If the treatment temperature is too low, it takes a long time to sufficiently cause the carbonation treatment reaction, which is not preferable. On the other hand, if the treatment temperature is too high, the carbonation treatment reaction is undesirably quick, but requires a large amount of energy. Incidentally, the heat of reaction during the carbonation treatment can be used as a heating source.

The time of the carbonation treatment (hereinafter referred to as "treatment time") varies depending on the type of calcium compound used, the treatment pressure and the treatment temperature, but is preferably 24 hours or less, more preferably 5 to 120 hours. Minutes.
If the treatment time is too short, the carbonation treatment reaction may not occur sufficiently. On the other hand, if the treatment time exceeds 120 minutes, no further effect can be obtained, and on the contrary, energy consumption and required equipment From the point of view, it is not industrially reasonable.

In the present invention, as described in claim 5, after adding water to the calcium compound and shaping it,
It is preferable to perform a carbonation treatment.

The amount of water to be added to the calcium compound is not particularly limited, and is appropriately selected depending on the specific surface area and shape of the calcium compound and the type and amount of other additives. If the amount is too low, the water filled between the calcium compound particles inhibits the progress of carbonation. Therefore, the amount is preferably 10 to 100 parts by weight based on 100 parts by weight of the calcium compound.

The method of shaping is not particularly limited, and a method of granulating to a predetermined particle size by a rolling granulation method, a stirring granulation method, etc., an extrusion molding method, a press molding method, etc. Shaping, and a method of crushing the obtained molded body to a predetermined particle size as necessary, and the like, but a rolling granulation method such as a bread mold is used in terms of operation costs, consumables costs and the like. Very advantageous.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Production of Dephosphorizing Material (Example 1) 30 parts by weight of water was added to 100 parts by weight of ordinary Portland cement, kneaded, and the hydrated reaction was allowed to proceed at room temperature for 28 days to obtain a cured product. Average particle size 0.1
The calcium compound obtained by pulverizing to a mm was treated with carbon dioxide in an autoclave under the conditions of 50 ° C. and 1.0 MPa for 1 hour, whereby the calcium compound was subjected to a carbonation treatment to obtain a dephosphorized material. .

(Comparative Example 1) As a dephosphorizing material, tobermorite (manufactured by Mitsubishi Materials Corporation, particle size of about 1 to 2 mm) was used without being subjected to a carbonation treatment.

Comparative Example 2 A dephosphorizing material was obtained in the same manner as in Example 1 except that no carbonation treatment was performed. Evaluation of dephosphorization performance

To the tap water, disodium hydrogen phosphate (manufactured by Wako Pure Chemical Industries, Ltd.) was added and dissolved, and the phosphorus concentration was 5 ppm.
Was obtained. 1000 g of the obtained phosphorus-containing water
5 g of the dephosphorizing material obtained in Example 1 and Comparative Examples 1 and 2
24 hours after the addition, the concentration of phosphorus in the phosphorus-containing water was measured using an ICP emission spectrometer (manufactured by Seiko Electronics Co., Ltd., model “S
PS4000 "). Next, disodium hydrogen phosphate having a phosphorus concentration of 5 ppm was further added to and dissolved in the phosphorus-containing water, and the phosphorus concentration in the phosphorus-containing water after 24 hours was measured using an ICP emission spectrometer. The obtained results are summarized in Table 1.

[0029]

[Table 1]

Production of Phosphorus- free Material (Example 2) A wood chip cement board waste material waste used for a house outer wall material was pulverized to obtain a cement powder. For 100 parts by weight of the cement powder, ordinary Portland cement 1
0 parts by weight were added, and the mixture was granulated while spraying water with a tumbling pan granulator to obtain a spherical granulated product having a diameter of about 2 to 8 mm. The water content of the obtained granules was 27% by weight.
The above-mentioned spherical granules are placed in an autoclave at 100
C., carbonation treatment of the calcium compound by treating with carbon dioxide for 30 minutes under the conditions of 0.9 MPa,
A dephosphorized material was obtained.

Example 3 A spherical granulated product was obtained in the same manner as in Example 2 except that wollastonite (manufactured by Shimizu Industry Co., Ltd., product number “K-160”) was used instead of cement powder. Was. The water content of the obtained granules was 24% by weight.
By treating the spherical granules with carbon dioxide in the same manner as in Example 2, the calcium compound was subjected to carbonation to obtain a dephosphorized material.

Example 4 The conditions for treatment with carbon dioxide were 2
Except for 3 minutes at 0 ° C. and 0.01 MPa,
A dephosphorizing material was obtained in the same manner as in Example 2.

(Comparative Example 3) A dephosphorized material was obtained in the same manner as in Example 2 except that no carbonation treatment was performed after granulation.

Comparative Example 4 A dephosphorized material was obtained in the same manner as in Example 3 except that after the granulation, no carbonation treatment was performed.

(Comparative Example 5) Tobermorite (manufactured by Klion Co., particle size of about 2 to 10 mm) was used as a dephosphorizing material.

(Comparative Example 6) An ALC plate (main component: tobermorite) as a wall material for a house was pulverized to a size of 2 to 8 mm.
A dephosphorized material was obtained.

Evaluation of Dephosphorization Performance Disodium hydrogen phosphate (manufactured by Wako Pure Chemical Industries, Ltd.) was added to tap water and dissolved to obtain phosphorus-containing water having a predetermined concentration as shown in Table 2. To 1000 g of the obtained phosphorus-containing water, 5 g of the dephosphorizing material obtained in Examples 2 to 4 and Comparative Examples 1 and 2 was added, and the phosphorus concentration in the phosphorus-containing water after 24 hours had passed was measured.
ICP emission spectrometer (Seiko Electronics Co., Ltd., model "SPS"
4000 "). Table 2 summarizes the obtained results.

[0038]

[Table 2]

Example 5 Ordinary Portland Cement 1
20 parts by weight of water was added to 00 parts by weight, and the mixture was mixed with a stirring mixer for 1 minute to obtain a granulated product, and the obtained granulated product was allowed to stand at room temperature for 24 hours. Thereafter, the particles were classified so that the average particle diameter became 10 mm.
By subjecting the calcium compound to a carbonation treatment by treating it with carbon dioxide for 30 minutes under the conditions of 10 MPa, a dephosphorized material was obtained.

Example 6 A dephosphorized material was obtained in the same manner as in Example 5, except that the particles were classified so that the average particle diameter became 15 mm.

Example 7 A dephosphorized material was obtained in the same manner as in Example 5, except that the particles were classified so that the average particle diameter was 0.8 mm.

Example 8 A dephosphorized material was obtained in the same manner as in Example 5, except that the particles were classified so that the average particle diameter became 120 mm.

Evaluation of Dephosphorization Performance To tap water, disodium hydrogen phosphate (manufactured by Wako Pure Chemical Industries, Ltd.) was added and dissolved to obtain phosphorus-containing water having a phosphorus concentration of 5 ppm. Example 5 was added to 1000 g of the obtained phosphorus-containing water.
~ 8, 5 g of the dephosphorizing material obtained in Comparative Example 1 was added, and the phosphorus-containing water was stirred by a stirrer while covering the dephosphorizing material with a wire mesh having a mesh interval of 1 mm. After a lapse of 24 hours, the phosphorus concentration in the phosphorus-containing water was measured using an ICP emission spectrometer (manufactured by Seiko Instruments Inc., model “SPS4000”). Next, all the phosphorus-containing water was discharged, 1000 g of 5 ppm phosphorus-containing water was newly added, and the phosphorus concentration in the phosphorus-containing water after 24 hours had elapsed was measured. Table 3 summarizes the obtained results.

[0044]

[Table 3]

[0045]

According to the method for producing a dephosphorized material of the present invention, a calcium compound is subjected to a carbonation treatment. Therefore, the dephosphorized material has calcium-eluting properties suitable as a dephosphorized material, does not produce coagulated precipitates, and It is possible to effectively remove phosphorus from the phosphorus-containing water without any trouble.

In the present invention, when wollastonite is used as a calcium compound, precipitation does not easily occur even at a high phosphorus concentration, and crystallization dephosphorization can be performed efficiently.

Further, in the present invention, when a cement material is used as a calcium compound, crystallization and dephosphorization can be carried out efficiently at a relatively low phosphorus concentration.

Further, in the present invention, when the particle size of the calcium compound is 2 to 100 mm, excellent handling properties can be obtained and phosphorus can be effectively removed from the phosphorus-containing water. Become.

Further, in the present invention, as described in claim 5, water is added to the calcium compound to shape it, followed by carbonation treatment, whereby a dephosphorized material having a desired particle size can be obtained. It is excellent in handling properties and can effectively remove phosphorus from phosphorus-containing water.

Claims (5)

[Claims] 1. A method for producing a dephosphorizing material, comprising subjecting a calcium compound to a carbonation treatment. 2. The method for producing a dephosphorized material according to claim 1, wherein the calcium compound is wollastonite. 3. The method for producing a dephosphorizing material according to claim 1, wherein the calcium compound is a cement material. 4. The calcium compound has a particle size of 2 to 100 m.
The method for producing a dephosphorized material according to any one of claims 1 to 3, wherein m is m. 5. The method for producing a dephosphorized material according to claim 1, wherein a carbonation treatment is performed after water is added to the calcium compound to shape the calcium compound.