JPH0626663B2 - Phosphorus removing material and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a phosphorus removing material for removing phosphorus contained in water at a low concentration, particularly, a phosphorus suitable for preventing eutrophication of dams, lakes and the like. The present invention relates to a removing material and a manufacturing method thereof.

[Conventional technology]

In recent years, eutrophication in stagnant waters such as lakes, seas and rivers has become a serious social problem. The main causative agent of eutrophication is considered to be nutrient salts or organic matter,
Among them, phosphorus is said to be one of the limiting factors for eutrophication. Therefore, as measures for preventing eutrophication, it is conceivable to remove phosphorus in wastewater flowing into rivers or take measures to prevent phosphorus elution from sludge accumulated in the bottom.

As means for removing phosphorus in water, there are coagulation sedimentation method, adsorption method, crystallization dephosphorization method, biological dephosphorization method, and as a means for preventing phosphorus elution in sludge, methods such as sand cover and dredging are available. is there.

[Problems to be Solved by the Invention]

However, as in the case of eutrophication in dams and lakes, the phosphorus concentration in the inflowing river water is generally about 0.07.
When the concentration is as low as mg / or less, but higher than the phosphorus concentration limit value of algae growth of 0.03 mg /, eutrophication occurs during storage, causing damage to tap water or fish farms at the discharge destination. Has a negative impact on the environment. In such a case, phosphorus sources are wide-ranging, such as farmland and domestic wastewater, and it is difficult to devise countermeasures for each source, and it is effective to directly dephosphorize river water. It has been considered difficult to dephosphorize water containing phosphorus at a concentration.

On the other hand, measures such as sand cover and dredging as a measure to prevent phosphorus elution in sludge are temporary, and dredging requires a great deal of cost to remove bottom sludge, and the treatment and disposal of removed sludge is also required. It was a troublesome problem.

The present invention solves the above-mentioned conventional problems, particularly efficiently removes phosphorus contained in a low concentration in a large amount of water such as river water,
It is possible to easily prevent eutrophication of dams and lakes,
Moreover, it is an object of the present invention to provide a phosphorus removing material and a method for producing the same, which can satisfy the strength required for forming a packed bed.

[Means for Solving the Problems]

The present invention is a phosphorus removing material obtained by molding a substance containing allophane as a main component and baking it at 300 to 600 ° C. It is also a method for producing a phosphorus-removing material, which comprises crushing and shaping a substance to be mentioned, and then firing and solidifying at 300 to 600 ° C.

[Work]

Raw materials for phosphorus removal material of the present invention, a material composed mainly of allophane, material mainly composed of this allophane, silicates aluminum _{[nSio 2 · Al 2 O 3 ·} nH 2 O (n = 1 ~ 2))
It is a substance containing as a main component and widely produced in the surface soil of the source of volcanic ash (Kanto volcanic ash layer, etc.). For example, excavations from Terauchi, Kanuma, and Osawa from Moka City, Tochigi Prefecture are listed, and their composition is as shown in the following table.

Such a substance containing allophane as a main component is
It is considered that the OH group contributes to the removal of phosphate ions,
It is preferable that the content of silicon and aluminum is high and the ratio of Si / Al is small. And, this material is molded and fired, but after many experiments,
It was confirmed that baking at 300 to 600 ° C shows extremely excellent phosphorus removal performance, and that the strength of the baked product is increased and the filling layer can be safely formed.

Fig. 1 shows that phosphorus is 0.05 mg / and 0.1 mg /, respectively.
Kanuma soil that has been baked at various temperatures is added to the contained liquid,
The result of measuring the phosphorus concentration in the liquid after reacting for 30 seconds is shown, and as shown in FIG. 1, the one burned at 200 to 600 ° C. has a phosphorus concentration limit value of 0.03 mg / or less for algal growth. It was confirmed that the phosphorus can be removed up to the above, and that especially the one fired at 300 to 600 ° C. has a significantly improved phosphorus removing ability as shown in Table 1.

In Table 1, Kanuma soil was granulated into a spherical shape with a diameter of 2 cm.
The results are obtained by finely pulverizing the dephosphorized material fired at 00 to 700 ° C and performing an adsorption test.

The mechanism of phosphorus removal by substances containing allophane as the main component is thought to be adsorption by functional groups present on the surface.
It is presumed that the reason why the phosphorus removal ability is particularly improved in the one baked at ~ 600 ° C is that the functional group on the surface is changed.

In this way, the phosphorus removing material obtained by molding and firing the substance containing allophane as the main component is filled in the phosphorus adsorption tower 1 to form the packed layer 2 as shown in FIG. 2, for example. The phosphorus removing material must have sufficient strength to form the filling layer 2, and it is important to satisfy the above conditions as shown in Table 2.

From Table 2, the strength is extremely higher in both air and water at 300 to 600 ° C than that of the others. Thus, practically, for example, when removing phosphorus in the inflow water of a dam, since the river that flows into the dam lake is filled with dephosphorization material for processing, even if the strength of the packing material is required on the handling surface, after granulation molding
It is of great practical value that the amount of phosphorus adsorbed and the strength can be improved by firing at 300 to 600 ° C.

Further, since the phosphorus removing material is porous and initially contains air therein, it is preferable to provide the water permeability suppressing member 3 in order to prevent floating. This phosphorus adsorption tower 1
When raw water containing phosphorus is passed in a downward flow, the phosphorus is adsorbed while the water passes through the packed bed 2 and, at the same time, a part of suspended matter in the water is also removed, and the treated water from which the phosphorus is removed Flows out of the system.

Then, while such a dephosphorization process is continued, the phosphorus removing material adsorbs phosphorus and becomes saturated, so that the adsorption-saturated phosphorus removing material is taken out from the phosphorus adsorption tower 1 and immersed in an alkaline solution or the like. It is easily reproduced. In that case, if the phosphorus removing material is filled in the net body 4 in an appropriate amount as shown in FIG.

When the raw water to be dephosphorized contains a large amount of suspended matter, the packed bed 2 is clogged with suspended matter. To avoid this, the raw material should be
It is preferable to calcine at 0 ° C. to obtain a calcined molded product. That is, after crushing the raw material, for example, it is molded into a rectangular parallelepiped having a large number of water permeation holes 5 as shown in FIG. 4 and fired, or a columnar shape having a single or a plurality of water permeation holes 5 as shown in FIGS. Alternatively, as shown in FIG. 7, the one formed into a spherical shape having a plurality of water permeation holes 5 and fired has no clogging and is easy to handle in terms of strength.

〔Example〕

A column with an inner diameter of 50 mm and a height of 1000 mm was filled with various phosphorus removal materials shown in Table-3, and the river water containing phosphorus of 0.07 mg / and turbidity of 50 degrees was LV.
The treatment results when water was passed at 90 m / day are as shown in Table 3, and it was shown that the phosphorus removing material obtained by the present invention had remarkably good phosphorus removing performance as compared with the comparative example.

[Effects of the Invention] As described above, according to the present invention, a large amount of an easily available substance containing allophane as a main component is molded and then fired at 300 to 600 ° C. to obtain a molded phosphorus excellent in phosphorus removing ability. It can be used as a dephosphorization material that can be used as a dephosphorization material that does not hinder the formation and handling of packed beds, and can efficiently and economically remove phosphorus contained in a large amount of river water at low concentrations. This is extremely advantageous for preventing eutrophication of dams, lakes and marshes.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the burning temperature and the phosphorus removing ability of a substance containing allophane as a main component, and FIG. 2 is an explanatory diagram of a phosphorus adsorption tower showing an example of dephosphorization treatment, and FIGS. FIG. 3 is an explanatory diagram showing a usage pattern of the phosphorus removing material of the present invention. 1 ... Phosphorus adsorption tower, 2 ... Packed bed, 3 ... Suppression member, 4 ... Net, 5 ... Water permeation hole.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Izumi Hirasawa 1-6-27 Konan Minato-ku, Tokyo Ebara In Filco Co., Ltd. (72) Minya Nakamura 1-6-27 Konan Minato-ku, Tokyo (56) References JP-A-57-24635 (JP, A) JP-A-58-177195 (JP, A) JP-B-49-9311 (JP, B2)

Claims (2)

[Claims] 1. A phosphorus-removing material obtained by molding a material containing allophane as a main component and then calcining the material at 300 to 600 ° C. 2. A material containing allophane as a main component, which is used as a phosphorus-removing material, is crushed after molding the material,
A method for producing a phosphorus removing material, which comprises baking at 600 ° C to solidify.