JPH10263577A - Porous filter media and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a porous filter media, in which continuous fine pores each having a shape and a size enough to allow a microorganism to live are formed. SOLUTION: The porous filter media consists essentially of cristobalite and zeolite and has many 1-20 μm radius continuous fine pores and is produced by adding combustible materials, which are formed by dividing into two meshes having different size from each other in the range of 0.59-1.19 mm and have ununiform shapes, into a porous filter media raw material consisting essentially of cristobalite and zeolite, granulating and firing while keeping 1000-1200 deg.C for 20-60 min.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inorganic porous filter medium useful as a microbial carrier for biological water treatment and the like and a method for producing the same, and more particularly, to a porous filter medium having a large number of continuous pores in the filter medium. And a method for producing the same, and a method for adjusting the formation of the continuous pores.

[0002]

2. Description of the Related Art Hitherto, a fired body containing cristobalite as a main component has been known and has a porous property, so that it has been used as a carrier for microorganisms in biological treatment of various industrial and domestic wastewaters, for example. . In this case, the fired body needs to form many pores for inhabiting microorganisms,
For this reason, by mixing and burning a combustible substance powder or granules in the raw material containing the above-mentioned cristobalite as a main component, the burnable substance of these powders or granules is burned off at the time of baking, and the same powder or granules are burned. There has been known a porous fired body mainly composed of cristobalite having pores corresponding to the shape and size of a granular material and having many pores.

[0003] In the above-mentioned conventional fired body containing cristobalite as a main component, a combustible substance added to form a large number of pores is a commercially available product from the viewpoint of easy availability and use. It was common to apply.

[0004]

However, the above-mentioned commercial products are uniform in both particle size and shape, and when such a combustible substance is mixed with a raw material containing cristobalite as a main component and fired, Although a large number of pores corresponding to the particle size and shape of these combustible substances are formed, these pores are independent of each other, and are disadvantageous to be unsuitable for microorganisms to inhabit. Further, when cristobalite alone is used as a raw material of the fired body, the average crush strength of the obtained fired body is fixed,
There was also an inconvenience that it was difficult to change the average crushing strength of the fired body corresponding to various uses. Therefore, the present invention overcomes various disadvantages observed in the prior art, aims to overcome the disadvantage of forming pores unsuitable for microorganisms to inhabit, and has a shape and size sufficient for microorganisms to inhabit. To provide a porous filter medium having continuous pores formed therein and a method for producing the same.

[0005]

The configuration of the present invention for achieving the above object is as follows. (1) Mainly composed of cristobalite and zeolite,
A porous filter medium having a large number of continuous pores having a radius of 1 to 20 μm. (2) The pore ratio of continuous pores having a radius of 1 to 20 μm is 40%
The porous filter medium as described in (1) above, wherein the average pore radius is 10 to 20 μm. (3) A porous filter material raw material containing cristobalite powder and zeolite powder as main components is sieved with two sieves having sieves of different sizes in a range of 0.59 to 1.19 mm and irregular in shape. Of flammable substances,
The porous filter medium according to the above (1), characterized in that after granulation, it is calcined so as to be held at 1000 to 1200 ° C for 20 to 60 minutes. (4) The porous filter medium according to (3), wherein the amount of the flammable substance added is 10 to 20 wt% based on the raw material of the porous filter medium.

(5) The porous filter medium according to (3), wherein the combustible substance is wood flour. (6) A porous filter material raw material containing cristobalite powder and zeolite powder as main components is sieved with two sieves having sieves of different sizes in a range of 0.59 to 1.19 mm and has irregular shapes. Of flammable substances,
A method for producing a porous filter medium, comprising firing after granulation at 1000 to 1200 ° C. for 20 to 60 minutes. (7) The method for producing a porous filter medium according to (6), wherein the amount of the flammable substance added is 10 to 20 wt% based on the raw material of the porous filter medium. (8) The method for producing a porous filter medium according to (6), wherein the combustible substance is wood flour.

(9) A porous filter medium raw material containing cristobalite powder and zeolite powder as main components,
Add a combustible material which is sieved through two sieves having sieves of different sizes in the range of 1.19 mm and irregular in shape, and after granulation, at 20-200 ° C. at 1000-1200 ° C.
A method of adjusting the radius of pores formed in the porous filter medium by adjusting the sieving range of the flammable substance when producing the porous filter medium by firing so as to be held for 60 minutes. (10) 0.59 to 1.19 mm is added to a porous filter material raw material containing cristobalite powder and zeolite powder as main components.
After adding a combustible material sieved with two sieves having sieves of different sizes in the range and irregular in shape, and granulated, the mixture is calcined at 1000 to 1200 ° C. for 20 to 60 minutes. A method of adjusting the proportion of pores formed in the porous filter medium by adjusting the amount of the flammable substance added when producing the porous filter medium.

[0008]

Next, the present invention will be described in detail.
An object of the present invention is to provide a porous filter medium having a large number of continuous pores in a radius of 1 to 20 μm and a method for producing the same, and a method for adjusting the radius and the formation ratio of the continuous pores. It is.

As a result of intensive studies to achieve this object, a mixture of cristobalite powder and zeolite powder, which is the same mineral resource, can be suitably used as a main raw material for producing a porous filter medium. That is, when the granulated material prepared from zeolite powder is calcined at 1000 to 1200 ° C. for 20 to 60 minutes, the crystal water to be retained is separated and hardened remarkably. When producing a fired body from a mixture in which powder is blended, the obtained fired body becomes stronger without impairing the porosity which is a property brought by firing of cristobalite, and further adjusts the mixing amount of the zeolite powder. This makes it possible to arbitrarily adjust the average crushing strength of the obtained fired body, so that a porous filter medium suitable for a wider range of applications can be provided, which is more preferable.

The zeolite used above is a natural zeolite, and there are two types of clinoptilolite type and mordenite type in mineralogy classification, and any type can be used. In order to form continuous pores sufficient for microorganisms in a porous filter medium composed of a mixture of the cristobalite powder and the zeolite powder, it is necessary to form a uniform and combustible flammable material having a uniform shape and particle size as in the related art. When a combustible material having an irregular shape and a particle size in a specific distribution range was used instead of the toxic material, it was found that desired continuous pores were formed.

Based on the above findings, as a result of searching variously for the materials of the corresponding flammable substances, wood flour (sawdust and the like) such as a sawmill satisfied the requirements. However, wood flours such as sawmills are extremely irregular in both shape and particle size, and need to be adjusted for particle size distribution in order to conform to the present invention. Wood powder having a particle size distribution can be prepared.In addition, even after sieving, it has the advantage of maintaining the irregularity of shape and particle size, and has the advantage that it can be easily obtained from a sawmill or the like. . Based on the above examination results, the mixture obtained by mixing the cristobalite powder and the zeolite powder in a mixture ratio of 60:40 to 40:60 was adjusted to a particle size of 0.59 mm to 1.19 by sieving.
A wood mill in the range of 1 mm was added at 10% by weight, granulated, and fired at 1000 ° C. for 20 to 60 minutes to produce a granulated fired body.

In the above, the particle size is 0.59 mm to 1.19 m
To be in the m range means that the opening is in a range from above the sieve of 0.59 mm to the opening of below 1.19 mm, and the particle size is 0.59 mm or less, 1.19 mm or more. Means that each eye is under a sieve of 0.59 mm,
It means that the opening is on a 1.19 mm sieve (hereinafter the same). When the state of the pores of the obtained granulated fired body was examined in detail, formation of a large number of extremely complicated continuous pores opened on the surface of the fired body was recognized, and the radius of these pores was 1 to It was confirmed that the structure was sufficient to allow microorganisms and the like having a size of 20 μm and usually having a size of 1 to 20 μm to enter and inhabit. In addition, by appropriately adjusting the particle size of the wood flour by sieving, the radius of the continuous pores to be formed can be arbitrarily adjusted. Therefore, it is possible to provide a fired body that is suitable for maintaining the inhabitation of various organisms ranging from microscopic bacteria to relatively large microorganisms according to the use. Furthermore, by appropriately adjusting the amount of wood powder added, it is possible to arbitrarily adjust the number of continuous pores to be formed.

In the above example, wood flour easily available from a sawmill or the like was used as the flammable substance. However, the present invention is not limited to this, and has flammability and a particle size and shape similar to wood flour. Any non-uniform substance can be used in the same manner as the combustible substance used in the present invention.

[0014]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. Example 1 Clinoptilolite-based zeolite (Okutama Kogyo K) was added to cristobalite powder (particle size: 150 μm or less; the same applies hereinafter).
A powder mixed so that the compounding ratio of zeolite powder (particle size: 150 μm or less; the same applies hereinafter) prepared from K, trade name “TZ-1510” (hereinafter the same) is 60:40 to 40: 60% by weight. The raw material has a particle size of 0.59mm each
Hereinafter, wood flour of 0.59 to 1.19 mm and 1.19 mm or more is added, and the mixture is humidified and kneaded so as to have a water content of 33 to 35% by weight. After drying, the particles were baked so as to be held at 1000 ° C. for 20 to 60 minutes.

The obtained granulated and baked filter medium has a granulation property,
The ratio of the pores having a radius of 1 to 20 μm (a value obtained by expressing the pore volume of the pore radius value as a percentage of the total pore volume; the same applies hereinafter), the average pore radius (50% passage diameter), When the ratio is represented in the form of an additive curve on a semilogarithmic graph, it means the pore radius when the cumulative pore volume becomes 50% of the total pore volume (hereinafter the same), and the fine pores formed The communication state of the holes was investigated, and the results are shown in Table 1.

[0016]

[Table 1]

As is clear from Table 1, when the particle size of the wood flour is 0.59 mm or less, the granulation property and the radius 1
Although the ratio of the fine pores in the range of ~ 20 µm is good, the average pore radius (50% passage diameter) is as small as 4.80 µm, and the communicating state of the fine pores is insufficient.
m, the granulation is good and the average pore radius (50%
(Pore diameter) is 10 μm or more, the ratio of pores having a radius of 1 to 20 μm is high, the communicating state of the pores is good, and a large number of complicated communicating pores are formed, and 1.19 mm
In the above case, the communication state of the pores is good, but granulation becomes very difficult because the volume of the wood flour is large, and the pore ratio and the average pore radius having a radius of 1 to 20 μm are also large. (5
It is known that the particle size of the wood flour to be added is preferably 0.59 to 1.19 mm. In addition, the measurement of the pore,
Mercury intrusion type pore size distribution analyzer (Paison 140 / Fisons)
140 type). (same as below).

Example 2 Clinoptilolite-based zeolite (Okutama Kogyo K) was added to cristobalite powder (particle size: 150 μm or less; the same applies hereinafter).
A powder mixed so that the compounding ratio of zeolite powder (particle size: 150 μm or less; the same applies hereinafter) prepared from K, trade name “TZ-1510” (hereinafter the same) is 60:40 to 40: 60% by weight. The raw material has a particle size of 0.59 to 1.19 m
m range of wood flour less than 10% by weight and 10% by weight respectively
More than 20% by weight and more than 20% by weight,
After moisture-mixing and kneading so that the water content is 33 to 35% by weight, rotary granulation is performed so that the particle size becomes 6 to 8 mm, and after drying, 1000 g.
It baked so that it may be hold | maintained at 20 degreeC for 20-60 minutes.

For each of the obtained granulated and baked filter media, the granulation property, the ratio of pores having a radius of 1 to 20 μm, and the average pore radius (5
0% passage diameter) and the communicating state of the formed pores,
Table 2 shows the results. FIG. 1 shows the relationship between the pore radius and the pore ratio of the granulated and baked filter medium to which 10% by weight and 20% by weight of wood powder were added, respectively.

[0020]

[Table 2]

As is clear from Table 2 and FIG. 1, when the amount of wood powder added is less than 10% by weight, the granulation properties and the ratio of pores having a radius of 1 to 20 μm are good, but the average When the pore radius (50% passage diameter) is as small as 3.02 μm and the communicating state of the pores is insufficient, the granulation property is good when it is 10% by weight or more and 20% by weight or less, The average pore radius (50% passage diameter) is as large as 10 μm or more, and the radius 1
The pore ratio of ~ 20 μm is high, the communication state of the pores is good, and a large number of complicated communication state pores are formed,
When the content exceeds 20% by weight, the communicating state of the pores is good, but the volume of the wood flour is large, so that granulation becomes very difficult. It is known that the average pore radius (50% passage diameter) is deteriorated. From this result, it is desirable that the addition amount of the wood flour having a particle size in the range of 0.59 to 1.19 mm is 10% by weight or more and 20% by weight or less. It has been found.

Example 3 A granulated and sintered filter medium manufactured by a conventional method (manufactured by Nippon Steel
Product name "SL-7", raw material: cristobalite, particle size 7
mm), and in Example 1, the particle size is 0.59 to 1.1.
The diameter of 6 mm prepared by adding 10% by weight of wood flour in 9 mm range
2 groups each of which randomly extracted 20 pieces of granulated and baked filter medium (the present invention) having a size of ８8 mm were formed.
Average pore radius (50% passage diameter) for two groups
And the pore ratio with a radius of 1 to 20 μm was investigated. For the other groups, the bacteria were immersed in the culture solution for 7 days to investigate the carrying properties of the bacteria. The results of the former are shown in Table 3, The latter result is shown in Table 4 and FIG.

[0023]

[Table 3]

[0024]

[Table 4]

As is evident from Table 3, the granulated and sintered filter medium of the present invention is structurally superior to the conventional granulated and sintered filter medium, and the number of adherent bacteria shown in Table 4 and FIG. Since the granulated and baked filter medium of the present invention is 80% higher than the conventional granulated and baked filter medium, the granulated and baked filter medium of the present invention is superior to the conventional granulated and baked filter medium in terms of bacterial support. It has been found. In addition, the test of bacteria carrying property utilized the method of counting the number of bacteria described in Japanese Patent Application No. 8-74407.

Comparative Example 1 A commercially available powdery combustible substance (eg, starch powder, etc.)
Most of them have a uniform shape, and the particle size is 100
Aligned to ~ 200 μm. When the average pore radius (50% passage diameter) when such a combustible substance is added is compared with the average pore radius (50% passage diameter) of the porous filter medium of the present invention, the former average pore radius is obtained. Hole radius (50% passing diameter) is 1μ
m or less, and the ratio was very small.

[0027]

According to the present invention, since the zeolite powder is mixed with the cristobalite powder as a raw material of the filter medium, the effect of increasing the strength of the obtained filter medium, particularly the average crushing strength, can be obtained. In addition, as a combustible substance, wood flour is used, but wood flour can be easily obtained from a sawmill or the like, and furthermore, the shape is not uniform by simple sieving, and a specific particle size distribution is obtained. As a result, the resulting filter media can form a large number of good and complex continuous pores compatible with microorganisms as desired by the present invention. Further, by adjusting the properties of the wood flour to be added, the size of the formed pores and the ratio thereof can be arbitrarily adjusted, so that a desired filter medium can be quickly prepared in response to various demands. To supply.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a powder raw material containing wood powder having a particle size of 0.59 to 1.19 mm in the form of cristobalite and zeolite as a main raw material.
The figure which shows the comparison of the pore distribution (pore ratio) of the filter medium formed when adding 10 weight% and 20 weight%, respectively.

FIG. 2 shows a filter medium manufactured by a conventional method and a particle size of 0.5.
The drawing which shows the comparison of the number of adherent bacteria with the filter medium (product of the present invention) in which a large number of pores having a radius of 1 to 20 μm are formed by adding 10% by weight of wood powder of 9 to 1.19 mm.

Claims (10)

[Claims] 1. A porous filter medium comprising cristobalite and zeolite as main components and having many continuous pores having a radius of 1 to 20 μm. 2. The ratio of continuous pores having a radius of 1 to 20 μm is 40% or more, and the average pore radius is 10 to 20 μm.
The porous filter medium according to claim 1, wherein m is m. 3. A porous filter medium raw material comprising cristobalite powder and zeolite powder as main components, comprising 0.59 to 1.1.
2 with different size sieves in the range of 9 mm
A flammable substance having an irregular shape, which is sieved through two sieves, is added, and after granulation, calcined so as to be held at 1000 to 1200C for 20 to 60 minutes.
The porous filter medium according to the above. 4. The porous filter medium according to claim 3, wherein the amount of the flammable substance added is 10 to 20% by weight based on the raw material of the porous filter medium. 5. The porous filter medium according to claim 3, wherein the combustible substance is wood flour. 6. A porous filter medium raw material comprising cristobalite powder and zeolite powder as main components, comprising 0.59 to 1.1.
2 with different size sieves in the range of 9 mm
A method for producing a porous filter medium, comprising adding a combustible substance having an irregular shape, which is sieved through two sieves, and granulating and firing the mixture at 1000 to 1200 ° C. for 20 to 60 minutes. 7. The method for producing a porous filter medium according to claim 6, wherein the amount of the flammable substance added is 10 to 20 wt% based on the raw material of the porous filter medium. 8. The method for producing a porous filter medium according to claim 6, wherein said combustible substance is wood flour. 9. A porous filter medium raw material comprising cristobalite powder and zeolite powder as main components, comprising 0.59 to 1.1.
2 with different size sieves in the range of 9 mm
When a combustible substance having an irregular shape is added by sieving through two sieves, and then granulated, the mixture is calcined at 1000 to 1200 ° C. for 20 to 60 minutes to produce a porous filter medium. A method of adjusting the radius of pores formed in the porous filter medium by adjusting the sieving range of the volatile substance. 10. A porous filter medium raw material containing cristobalite powder and zeolite powder as main components, comprising 0.59 to 1.
A combustible material which is sieved through two sieves having different sieve sizes in the range of 19 mm and irregular in shape is added, and after granulation, 20 to 60 at 1000 to 1200 ° C.
A method of adjusting the proportion of pores formed in the porous filter medium by adjusting the amount of the flammable substance when the porous filter medium is manufactured by baking so as to be held for one minute.