JP3388966B2 - Granular phosphorus adsorbent - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to water in rivers and lakes,
The present invention relates to a novel phosphorus adsorbent capable of effectively removing phosphorus from sewage and waste water (hereinafter, also referred to as dephosphorization agent), and a method for removing phosphorus from various waters (hereinafter, also referred to as dephosphorization method) using the same. The phosphorus removal technique of the present invention is particularly suitable for removing a trace amount of phosphorus at a level of 0.1 mg / liter or less contained in a large amount of natural environment water such as a river.

[0002]

2. Description of the Related Art Conventionally known granular phosphorus adsorbents include activated alumina and fired Kanuma soil granulated products. However, these phosphorus adsorbents have the following problems, and further development of an ideal phosphorus adsorbent (hereinafter also referred to as "dephosphorizing agent") is desired. 1. Since activated alumina is granulated and fired, which is expensive per se, the price becomes higher, and it is not suitable for the treatment of a large amount of water which requires low running cost. 2. When used in a river, it is often filled in a water-permeable container and installed in the water passage of the river.
Both activated alumina and Kanuma soil must have a large particle size of several centimeters in order to prevent clogging of the packing material due to the turbidity of the river. The inside of the granules cannot be used for phosphorus adsorption because of poor diffusion into the granules. 3. Granules of Kanuma soil have relatively low phosphorus adsorption capacity. 4. Kanuma soil granulation and firing equipment is required, and the cost for firing is required. 5. The strength of the granulated material is as hard as stone, and the natural degradability is slow when the waste dephosphorizing agent is sprayed and disposed on forest land.

[0003]

SUMMARY OF THE INVENTION The present invention aims to solve the above-mentioned drawbacks of the prior art. Specifically, the following matters are to be solved. 1. It is possible to effectively granulate phosphorus-adsorbing fine particles such as iron hydroxide and aluminum hydroxide, which have been difficult to be granulated while maintaining high phosphorus-adsorbing property, to be porous. 2. The manufacturing process of granular dephosphorizing agent is very simple. 3. No need to bake the granules. 4. Excellent phosphorus adsorption and phosphorus adsorption. 5. Even if the granular dephosphorizing agent is porous and has good water permeability, and the particle size is 1 cm or more, the inside of the dephosphorizing agent can be used for phosphorus adsorption. 6. The strength of the waste dephosphorizer is not too hard and the natural disintegration property is good,
Easy to dispose. 7. Dephosphorizers are low-priced and suitable for large-volume water treatment.

[0004]

The object of the present invention can be solved by the following technical constitution. (1) A granular phosphorus adsorbent obtained by kneading and granulating a mixture of phosphorus-adsorptive fine particles, a calcium salt, water and a superabsorbent polymer. (2) A method for removing phosphorus, which comprises contacting the granular phosphorus adsorbent of (1) with phosphorus-containing water.

As the phosphorus-adsorptive fine particles, iron hydroxide, iron oxide, aluminum hydroxide, aluminum oxide, allophane, Kanuma soil, activated alumina, zirconium oxide, phosphate rock, bone charcoal, etc. can be adopted, but especially iron hydroxide, Aluminum hydroxide is most preferred for the present invention. The present inventor has found that the slurry of iron hydroxide and aluminum hydroxide fine particles having excellent phosphorus adsorption is polyferric sulfate (commonly called "polyiron"),
It has been found that it can be produced by neutralizing an aqueous solution of an iron salt or an aluminum salt such as ferric chloride, a sulfuric acid band, and PAC with an alkali to a pH range of 6 to 8. FIG. 1 shows a phosphorus adsorption isotherm of iron hydroxide fine particles prepared by this method. According to this, it is recognized that the phosphorus adsorption performance is excellent. The aluminum hydroxide fine particles also show the same phosphorus adsorption isotherm as in FIG. As the alkali, magnesium hydroxide, slaked lime, sodium hydroxide or the like can be adopted.

[0006]

According to the experiments of the present inventor, it is surprising to knead phosphorus-adsorptive fine particles, calcium salt (various kinds of gypsum, calcium carbonate, etc., types are not limited), water and super absorbent polymer. In particular, it was found that the granules became remarkably porous aggregates, and an elastic body having an appropriate strength was formed. As shown in FIG. 3, the structure of the obtained phosphorus adsorbent 1 is such that countless small particles (phosphorus adsorptive fine particles 2) such as “Okoshi” of confectionery mediate the superabsorbent polymer gel 3 absorbing water. To form a porous aggregate structure 4. The superabsorbent polymer used in the present invention includes various superabsorbent polymers (polyacrylate, starch-acrylate graft polymer, vinyl acetate copolymer, polyvinyl alcohol, etc.) which are frequently used in diapers and the like. ) Can be used, but one having a large water absorption is particularly preferable. With respect to the amount of water absorption, it is preferable that 300 g or more of pure water can be absorbed per 1 g of superabsorbent polymer powder.

An example of a typical manufacturing process of the granular dephosphorization agent (phosphorus adsorbent) of the present invention will be described with reference to FIG. For example, if gypsum is added to and mixed with ferric hydroxide fine particle slurry or aluminum hydroxide fine particle slurry (water content of about 90%), which has excellent phosphorus adsorption properties, and then super absorbent polymer powder is added, high water absorbency and high The molecules quickly absorb the water of the iron hydroxide and aluminum hydroxide fine particle slurry, and the superabsorbent polymer particles swell. When this is kneaded for several minutes, the polymer swollen by absorbing water has an adhesive force like a paste, and serves as a binder to effectively aggregate iron hydroxide and aluminum hydroxide fine particles. At this time, the presence of gypsum causes the superabsorbent polymer gel swollen by absorbing water to exhibit a gel hardening phenomenon due to the action of calcium ions, resulting in a marked increase in strength. If this is shaped into an appropriate particle size and shape (for example, extrusion granulation method), a porous granular dephosphorizing agent having elasticity that does not collapse even when immersed in water can be obtained. According to this production means, the drying step required for the production of the conventional dephosphorization agent,
A porous granular dephosphorizing agent can be produced in a short time by a very simple process without providing a firing process. If it is desired to further increase the strength, a small amount of cement may be used together.

In order to remove phosphorus from the phosphorus-containing water using the granular dephosphorizing agent of the present invention, the granular dephosphorizing agent may be packed in a column or the like and the phosphorus-containing water may be passed through at an appropriate space velocity (SV). In order to remove phosphorus from a river, a method of packing a dephosphorizing agent granulated into a few centimeters in a water-permeable container such as a net bag or a wire mesh basket and submerging it in the river is the method of removing the phosphorus due to the turbidity of the river. It can be recommended as the simplest phosphorus removal technology with less clogging of phosphorus agents.

The prior application of the present inventor (Japanese Patent Laid-Open No. 6-154)
No. 597) "Composite particulates of metal hydroxide and super absorbent polymer" utilize super absorbent polymer.
The action of the superabsorbent polymer is essentially different from that of the present invention. That is, the prior application technology is "made of a superabsorbent polymer, which retains a metal hydroxide inside each hydrogel particle which swells in water and exhibits elasticity". Since it is produced by mixing a metal salt aqueous solution with a metal salt solution and hydrolyzing the metal salt in the mixture, the metal hydroxide is uniformly dispersed in the superabsorbent polymer as extremely fine particles or gel. It exists in the state of being. Therefore, as shown in FIG. 4, it has a structure in which the solid phase of the adsorbent is diffusion-fixed in the entire network structure of the superabsorbent polymer. That is, the phosphorus adsorbent 11 is in a state in which extremely small particles of the metal hydroxide as an adsorbent are uniformly dispersed in the superabsorbent polymer gel 3.

On the other hand, in the present invention, since the phosphorus-adsorptive fine particles are kneaded and granulated with the superabsorbent polymer, the phosphorus-adsorptive fine particles themselves are mixed to some extent with the superabsorbent polymer. As shown in FIG. 3, the phosphorus-adsorptive fine particles form a nodule structure, and the superabsorbent polymer gel is present as a binder in the voids and the surroundings thereof so that the superabsorbent polymer has a high water-absorption property. The polymer-adsorbing fine particles have a structure in which the polymer gel particles are formed. Some of the phosphorus-adsorptive fine particles are retained inside the gel particles and others are exposed on the gel particle surfaces. In addition, the prior application is to utilize each of the hydrogel particles as a phosphorus adsorbent having a small particle diameter in a dispersed state. As in the present invention, the dephosphorization of a large particle having an aggregate structure as a skeleton is performed. It is not used as an agent or a filler.

[0011]

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. (Example 1) Polyiron stock solution was diluted three times with tap water (pH
2) Magnesium hydroxide was added to this to neutralize it to pH 7 to obtain ferric hydroxide fine particle slurry having good phosphorus adsorption. After adding 50 g of gypsum to 300 cc of this slurry and adding 70 g of superabsorbent polymer powder and kneading for 3 minutes, it easily aggregated into a porous nodule. Further poly-iron 3
When 100 cc of the double-diluted solution was added and kneaded, the strength of the granulated product increased and the granulated product did not disintegrate even in water. When this was molded into a particle size of 10 to 12 mm and air-dried for 2 hours, the strength was further increased, and a porous dephosphorization agent having an appropriate elasticity (which can be broken by grasping it with a strong hand) was produced. .

(Example 2) Liquid sulfuric acid band (liquid bun) A stock solution diluted two-fold was added with sodium hydroxide, and the p
Neutralization with H6 gave aluminum hydroxide fine particle slurry with good phosphorus adsorption. After adding 30 g of calcium carbonate to 300 cc of this slurry, super absorbent polymer powder was added to 60 cc.
When g was added and the mixture was kneaded for 2 minutes, it was easily agglomerated, and the same porous dephosphorizing agent as in Example 1 was produced.

Example 3 To 150 g of Kanuma soil (phosphorus-adsorptive) powder produced in Kanuma City, Tochigi Prefecture, 100 cc of water, 30 g of gypsum, and 15 g of cement were added, and then 100 g of superabsorbent polymer powder was added. When the mixture was kneaded, it became a porous nodule easily, and a porous dephosphorizing agent having high strength could be produced. (Example 4) A phosphorus removal column test was performed using the dephosphorizing agent produced in Examples 1 to 3. Table 1 shows the test conditions and the test results.

[0014]

[Table 1]

It can be seen from Table 1 that the dephosphorizing agent of the present invention exhibits a good dephosphorizing performance, and particularly that using iron hydroxide fine particles and gypsum as raw materials shows high performance. Raw water p
The treated water pH was 7.3 to 8.3 for H7.0.
The water quality regulation value was satisfied.

[0016]

【The invention's effect】

1. A porous dephosphorizing agent having a proper strength can be produced very easily and in a short time without complicated operations such as drying and firing. Therefore, it is suitable for mass production, and the manufacturing equipment cost and running cost can be significantly reduced as compared with the conventional one. 2. Since it is porous, the surface area of the phosphorus adsorption surface is large and the phosphorus adsorption performance is good even with a large particle size. 3. Since the strength is appropriate and the natural degradability is excellent, it is easy to disperse the waste dephosphorizing agent to the forest.

[Brief description of drawings]

FIG. 1 is a graph showing a phosphorus adsorption isotherm of iron hydroxide fine particles used in the present invention.

FIG. 2 is a process drawing showing a typical production example of the phosphorus adsorbent of the present invention.

FIG. 3 is a conceptual diagram showing the structure of a granular phosphorus adsorbent of the present invention.

FIG. 4 is a conceptual diagram showing the structure of a conventional phosphorus adsorbent.

[Explanation of symbols]

1 Granular phosphorus adsorbent 2 Phosphorus adsorptive fine particles 3 Super absorbent polymer gel 4 Aggregate structure 11 Phosphorus adsorbent 12 Metal hydroxide

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Ishii 2-14-2 Kojimachi, Chiyoda-ku, Tokyo Kojimachi NK Building Inside the dam water source environment preparation center (72) Inventor Katsuyuki Kataoka Fujisawa City, Kanagawa Prefecture Hon Fujisawa 4-2-1 EBARA Research Institute Co., Ltd. (72) Inventor Shigeru Kobayashi 11-11 Haneda Asahi-cho, Ota-ku, Tokyo Incorporated EBARA CORPORATION (72) Inventor Yoshinori Asai Haneda, Ota-ku, Tokyo Asahimachi No. 11-1 EBARA CORPORATION (56) References JP-A-6-182358 (JP, A) JP-A-48-22374 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C02F 1/28 C02F 1/58 B01J 2/00-2/30 B01J 20/00-20/34

Claims (2)

(57) [Claims] 1. A granular phosphorus adsorbent obtained by kneading and granulating a mixture of phosphorus-adsorptive fine particles, a calcium salt, water and a superabsorbent polymer. 2. A method for removing phosphorus, which comprises contacting the granular phosphorus adsorbent according to claim 1 with phosphorus-containing water.