JP2001096289A - Carrier for microorganism immobilization and process and equipment for purifying sewage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microorganism immobilization carrier which is capable of effecting a high microorganism growth rate and has a wide specific surface area, good air permeability, high sewage treatment capacity and excellent sewage purification performance and also to provide a sewage purification process using the carrier and a sewage purification equipment for the process. SOLUTION: This microorganism immobilization carrier 3 is prepared by depositing and supporting microorganisms on the surface of a carrier formed from flexible polyurethane foam having no cell membrane.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a high specific surface area,
The air flow to the inside is good, and the growth rate of microorganisms is high,
A microorganism-immobilizing carrier for sewage treatment that can be used for sewage and wastewater treatment, and can be used for sewage and wastewater treatment, and a purification method for sewage using the microorganism-immobilizing carrier and sewage. The present invention relates to a purification device.

[0002]

2. Description of the Related Art As a purification method for wastewater treatment, there are known methods using various treatment tanks such as a household septic tank and a wastewater treatment tank for a plant. In such a method, an aeration tank containing a microorganism-immobilized carrier as a fixed reef or a fluid reef is usually used.

Here, the sewage treatment method using an aeration tank is a method in which sewage is accommodated in an aeration tank, and air is supplied into the sewage by an aeration device, and the flowing air and sewage are brought into contact with a carrier to perform treatment. It is. The microorganism used in the above treatment is an aerobic bacterium, and the carrier to which the microorganism is attached is generally called a microorganism-immobilized carrier, and fixed reefs and fluid reefs are known. A polyethylene foam or the like is used as a fluid reef such as a resin molded product or the like (Japanese Patent Laid-Open No. 10-15572, JP-A-6-2338).
No. 2, No. 9-85285).

However, when the carrier is a resin, the specific surface area is limited, the amount of microorganisms generated is limited, and it can be used only on fixed reefs and cannot be used as a fluid reef. There is also a problem that sewage cannot be completely treated.

[0005] On the other hand, in the case of polyethylene foam, air permeability is low due to low air permeability, microorganisms propagate only on the outer surface of the carrier, and utilization of internal voids cannot be expected. There is a problem that the performance cannot be improved beyond the purification ability.

The present invention has been made in view of the above circumstances, and has a large specific surface area, good air permeability, and a high growth rate of microorganisms, so that it has a high purification ability and is advantageous in reducing the cost of sewage treatment equipment. An object of the present invention is to provide a microorganism-immobilized carrier, a purification method and a purification device using the microorganism-immobilized carrier.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, by using a flexible polyurethane foam without a cell membrane as a microorganism-immobilizing carrier, the specific surface area was widened. The air flow to the inside is good, it can be a good environment for breeding microorganisms,
In addition to finding that it can exhibit good performance for sewage treatment, based on these findings, succeeded in obtaining an advantageous purification method and purification device using the microorganism-immobilized carrier, and achieved the present invention. It is something that has been done.

Accordingly, the present invention provides the following microorganism-immobilized carrier, and a method and an apparatus for purifying sewage using the microorganism-immobilized carrier. Claim 1: A microorganism-immobilized carrier having a microorganism adhered and supported on a surface thereof, wherein the microorganism-immobilized carrier is formed of a flexible polyurethane foam without a cell membrane. In a preferred embodiment, the polyurethane foam has an air permeability of 30 to 40.
2. The microorganism-immobilized carrier according to claim 1, wherein the carrier is 0 cc / cm ² / sec. Claim 3: The polyurethane foam has a density of 0.015 to 0.015.
3. The microorganism-immobilized carrier according to claim 1, wherein the carrier is 0.070 g / cm ³ . Claim 4: The cell number of the polyurethane foam is 5 to 70 /
The microorganism-immobilized carrier according to any one of claims 1 to 3, which is an inch. Claim 5: The hardness of the polyurethane foam is 5 to 30 kg.
The microorganism-immobilized carrier according to any one of claims 1 to 4, which is f. Claim 6: The length of one side of the microorganism-immobilized carrier is 4 to 50 m.
The microorganism-immobilized carrier according to any one of claims 1 to 5, which has a cubic or rectangular parallelepiped shape of m. [7] The carrier for immobilizing microorganisms according to any one of [1] to [6], wherein the carrier for immobilizing microorganisms is a flexible polyurethane foam having no cell membrane and a surfactant attached to the surface of a skeleton. Claim 8: The microorganism-immobilized carrier is obtained by immersing a flexible polyurethane foam without a cell membrane in water in which a surfactant is dispersed, squeezing the water, and drying the water to attach the surfactant to the surface. The microorganism-immobilized carrier according to claim 7. In a ninth aspect, sewage is introduced into an aeration tank containing a microorganism-immobilized carrier therein, and the sewage is brought into contact with the microorganism-immobilized carrier by contacting the sewage with the air while supplying air to the sewage. A method for purifying sewage, wherein the microorganism-immobilized carrier is the microorganism-immobilized carrier according to any one of claims 1 to 8. In another preferred embodiment, the sewage treatment is performed in the presence of a surfactant. Claim 11: In a purification device comprising an aeration tank containing an aeration device and a microorganism-immobilized carrier, the microorganism-immobilized carrier is the microorganism-immobilized carrier according to any one of claims 1 to 8. Purification device characterized by the above-mentioned. In a preferred embodiment, the carrier for immobilizing microorganisms is a fixed reef or a fluid reef.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The microorganism-immobilized carrier of the present invention is formed of a flexible polyurethane foam without a cell membrane. This flexible polyurethane foam without a cell membrane can be produced by the same formulation as a normal polyurethane foam. For example, a flexible polyurethane foam having a cell membrane by using a compound mainly composed of a polyol, an isocyanate and a foaming agent After the cell is manufactured, the cell membrane is removed by a method such as an explosion treatment or an alkali treatment to obtain a three-dimensional network skeleton structure, or a method of obtaining a flexible polyurethane foam using a compound that does not generate a cell membrane. be able to.

As described above, the microorganism-immobilized carrier of the present invention is formed of a flexible polyurethane foam without a cell membrane. In this case, the air permeability is JIS-K.
In accordance with 6400, JIS-
Breathable according to K6400, usually 30 cc / cm ² /
sec or more, preferably 30 to 400 cc / cm ² / s
ec, more preferably 100 to 300 cc / cm ² / s
ec is recommended. This value is a value when the thickness of the polyurethane foam is 10 mm. If the air permeability is too low, the passage of air and sewage may be insufficient. The air permeability may be higher than the above value, but if it is too high, the production may be difficult.

The density of the flexible polyurethane foam is usually 0.015 to 0.070 g / cm ³ , particularly 0.02 to 0.04 g / cm ³ , and if the density is too high, the air permeability becomes low. If it is too low, a problem may occur in durability.

Further, the number of cells of the above-mentioned flexible polyurethane foam is usually 5 to 70 / inch, preferably 10 to 40 / inch. If the number of cells is too large, the air permeability becomes low. And the growth of microorganisms may be impaired.

In the present invention, the soft polyurethane foam has a hardness of usually 5 to 30 kgf, particularly 5 to 15 kgf.
kgf is recommended, and if too hard, the durability may be degraded. Note that this hardness is JIS-K6400
It is a measured value by.

As such a flexible polyurethane foam, commercially available products can be suitably used, and specifically, Everlite SF (manufactured by Bridgestone Corporation) and the like can be used.

The carrier for immobilizing microorganisms of the present invention can be used in any of fixed reefs and fluid reefs. The fixed reefs include lattices, pipes, aggregates of pipes, corrugated plates, and honeycombs. It can be formed into a known shape such as a string shape, a hem shape or the like. Further, the shape as a fluid reef can be formed in a cube shape (cube, rectangular parallelepiped) having a side length of 4 to 50 mm, particularly 10 to 25 mm. If the length of one side is short, it tends to flow out of the tank at the time of drainage. If the length of one side is too long, aerobic bacteria may not be able to adhere to the inside of the carrier.

The carrier for immobilizing microorganisms of the present invention is formed of the above-mentioned flexible polyurethane foam, but may float on sewage due to the properties of the foam. Therefore, in the present invention, it is recommended to use a surfactant in order to efficiently immerse the foam in sewage and increase the purification treatment ability. The treatment with a surfactant can be suitably used for both fixed reefs and fluid reefs. In the case of a fluid reef in particular, it is recommended that the treatment with a surfactant be also employed.

Here, as the surfactant which can be used in the present invention, known surfactants can be mentioned, and specifically, anionic surfactants such as ethylene oxide, alkali salts of higher fatty acids, and alkyl sulfonates. Surfactants, higher amine halides, cationic surfactants such as quaternary ammonium salts, polyethylene glycol alkyl ethers,
Nonionic surfactants such as sorbitan fatty acid esters,
Examples include amphoteric surfactants such as amino acids.

Among the above-mentioned surfactants, the use of a modified product of sodium succinate is particularly preferred in terms of the effect.
In this case, as the sodium succinate modified product, sodium dialkyl succinate sulfonate represented by the following formula is preferably used.

[0019]

Embedded image (However, R is an alkyl group or an aralkyl group, and includes those having 1 to 18 carbon atoms.)

Specific examples of the ester include di-n-amyl, di-n-hexyl, di-n-heptyl, di-n-octyl, di-n-nonyl, monoethyl monododecyl and monobutyl monododecyl. Mono-2-ethylhexyl-mono-1-methylbenzyl, mono-2-ethylhexyl-
Mono-1-methyl-4-ethylhexyl, di-1-methylbutyl, di-2-methylbutyl, di-isoamyl, di-1,3-dimethylbutyl, di-1-methylamyl, di-1,1-dimethylamyl, Di-1-isopropylisobutyl, di-1-propylbutyl, di-1-methylhexyl, di-2-ethylhexyl, di-1-methylheptyl, di-1-butylamyl, di-1-isobutyl-3-
Methylbutyl, di-1-methyl-4-ethylhexyl,
Di-1-methyl-4-ethyloctyl and the like.
As such a sulfosuccinic acid diester type surfactant, a commercially available product may be used. For example, Sanmorin OT70 manufactured by Sanyo Chemical Industries is preferably used.

Such a surfactant is preferably a water-soluble one, if possible, because it is easy to disperse uniformly in sewage, and it is only necessary to dry the foam when it is subjected to an adhesion treatment as described later. . In addition, although the usage-amount of a surfactant differs also with the required performance, for example, when disperse | distributing uniformly in sewage, 0.01 to 10 g is usually used.
/ L, preferably about 0.05 to 5 g / L, and more preferably about 0.1 to 2 g / L. Also,
When using what has been attached to the foam, it is usually 0.1 to 100 g / L, preferably 0.5 to 50 g in water.
/ L, more preferably about 1 to 20 g / L, is recommended to be subjected to an adhesion treatment as described later using an aqueous solution. In any case, if the amount is too small, the microorganism-immobilized carrier may float without sinking, and if the amount is too large, bubbles may be formed too much and the microorganism-immobilized carrier may float.

In the present invention, the method of using the surfactant is such that the foam is efficiently submerged in water as described above, and the method of directly adding the surfactant to the sewage so as to have the content described above. However, any method may be used as the method of pre-attaching to the flexible polyurethane foam, and by adopting any of these methods, it is possible to prevent the flexible polyurethane foam from floating and efficiently purify wastewater. Can be.

Here, as a method of adhering a surfactant to the flexible polyurethane foam, a flexible polyurethane foam as a microorganism-immobilizing carrier of the present invention is placed in water in which a predetermined amount of the surfactant is dispersed as described above. After immersion in water, a method of squeezing water and drying can be adopted. By employing this method, a surfactant can be made to adhere to the surface of the polyurethane foam subjected to the drying treatment.

When the treated flexible polyurethane foam is used as a carrier for immobilizing microorganisms,
It can be used in an aeration tank in the same manner as a usual immobilized carrier. In this case, due to the action of the surfactant attached to the surface, the foam can adapt to the wastewater without floating, can be sufficiently immersed, and the purification treatment using the microorganism-immobilized carrier can be performed smoothly. In particular, even when a reef is used, the above purification can be performed efficiently.

In the present invention, a surfactant can be directly added to wastewater.
As in the case of treating the microorganism-immobilized carrier in advance with a surfactant as described above, the carrier is smoothly adapted to the sewage and can be immersed in the sewage without floating, so that purification is performed in the same manner as described above. Processing can be accelerated.

A known method can be adopted for attaching microorganisms to the microorganism-immobilized carrier of the present invention, and aerobic microorganisms can be adhered in the same manner as a conventional microorganism-immobilized carrier.

The microorganism-immobilized carrier disposed in the aeration tank described below means a microorganism-immobilized carrier to which microorganisms have already adhered. In addition, since the treatment with the surfactant can be performed in the same manner as described above, the description thereof is omitted.

Next, the apparatus of the present invention will be described with reference to the drawings. FIGS. 1 and 2 are schematic views showing a purifying apparatus 1, 1 'of the present invention. Tank 2
The aeration tank 2 contains the microorganism-immobilized carrier 3 of the present invention.

The microorganism-immobilized carrier 3 disposed in the aeration tank 2 of FIG. 1 represents a fixed reef 3a, and the microorganism-immobilized carrier 3 accommodated in the aeration tank 2 of FIG. 2 represents a flowing reef 3b. 1 and 1 'have the same configuration except that the carrier for immobilizing microorganisms is different. Therefore, the same reference numerals are given and the description of each device is omitted.

In FIG. 1, a fixed reef 3a of the present invention is a fixed reef formed in a corrugated plate shape, and three microorganism-immobilized carriers 3a formed in the same shape are separated from each other by a predetermined distance. It is disposed along the vertical direction from one end to the other end in the vertical direction. The upper and lower ends of the microorganism-immobilized carrier 3a are swingably held in the aeration tank 2.

The fluid reef 3b in FIG. 2 contains a plurality of microbe-immobilized carriers 3b formed in a cube shape, and these carriers are composed of several types of cubes and rectangular parallelepipeds having different side lengths. And is dispersed in the sewage supplied into the aeration tank 2.

On the other hand, the bottom of each aeration tank 2 is provided with an aeration device 4
Is disposed so that air is spouted from a spout (not shown) into the sewage.

An inlet 5 for introducing sewage into the aeration tank 2 is formed at one location on the upper side wall of each aeration tank 2, and the inlet 5 is connected to the second delivery pipe 6. The sewage introduced from the sewage introduction pipe 7 is subjected to a predetermined treatment through the first anaerobic filtration tank 8 and the second anaerobic filtration tank 9, and then passes through the second delivery pipe 6, and passes through the introduction port 5. From the aeration tank 2.

In this case, the first anaerobic filtration tank 8 and the second anaerobic filtration tank 9 are connected via a first delivery pipe 10, and the filtrate filtered by the first anaerobic filtration tank 8 is supplied to the delivery pipe 1.
0, and is introduced into the second tank 9 for anaerobic filtration.

Although not shown, the anaerobic filtration first tank 8 and the second tank 9 are each provided with a filter medium having a different hole diameter, and the filter medium in the first tank 8 has a hole diameter of the second tank. The filter medium is larger than the filter medium in No. 9 and is configured to perform stepwise removal of foreign substances from the passing sewage and treatment with anaerobic bacteria.

On the other hand, a processing liquid discharge port 11 is formed at another position on the side wall of each aeration tank 2, and treated water that has been treated and purified in the aeration tank passes through the discharge port 11. It is discharged to the outside, passes through a pipe (not shown) connected to the discharge port 11, and is further discharged to a river through a disinfection tank (not shown).

Next, a method of treating sewage by using the above-mentioned purifying apparatus will be described. First, sewage to be treated is introduced into a first anaerobic filtration tank 8 through a sewage introduction pipe 7, and a filter medium in the tank is removed. After passing through, it is introduced into the anaerobic filtration second tank 9 through the first delivery pipe 10. Thereby, the sewage is decomposed by the anaerobic bacteria while passing through the filter medium provided in each tank, and is further sent to the second delivery pipe 6.

The sewage introduced into the aeration tank 2 from the introduction port 5 through the second delivery pipe 6 is stored in the aeration tank in a predetermined amount so as to be subjected to microbial treatment by aerobic bacteria. Air is continuously ejected by the operation of the aeration device 4 housed in the aeration tank. Thereby, the sewage flows in the direction of the dotted line arrow in the figure, and circulates in the tank as a predetermined liquid flow.

Here, in the fixed reef of FIG. 1, the microorganism-immobilized carrier 3a is provided so as to be swingable, so that it swings while following the liquid flow of the sewage, without excessively obstructing the flow of the liquid flow. The treatment is performed by contact with sewage. Further, in the fluidized reef of FIG. 2, the microorganism-immobilized carrier 3b comes in contact with sewage while flowing with the liquid flow, and circulates in the tank with the liquid flow while performing the treatment.

In any case, the liquid flow of the sewage circulates without stagnation in the microorganism-immobilized carrier and continuously contacts the carrier, so that the treatment of the sewage by aerobic bacteria is performed efficiently.

On the other hand, a large amount of air bubbles A ejected by the aeration device 4 are present in the flowing sewage and come into contact with the microorganism-immobilizing carrier according to the liquid flow in the same manner as in the above-described sewage. The air required for microorganisms attached to the immobilized carrier is supplied.

As described above, the treated water treated by the microorganism-immobilized carrier is discharged through a pipe to the outside of the aeration tank through the discharge port 11 formed on the other end face of the upper wall side, and It is treated in a disinfection tank in another process and finally released into rivers.

Thus, in the above-described method for purifying sewage, the carrier for immobilizing microorganisms has good air permeability, a high surface adhesion rate of microorganisms, a large specific surface area, excellent water permeability, and stirring conditions can be selected. It has a wide range of uses and exhibits good purification performance even when used in either fixed reefs or fluid reefs.

In particular, the microorganism-immobilized carrier has good air permeability and a large specific surface area, so that the range of adhesion of microorganisms is increased, and air during aeration is passed through to the inside of the carrier.
Since microorganisms can adhere to and propagate inside the carrier, the purification ability can be dramatically improved.

Therefore, the microorganism-immobilized carrier of the present invention has a higher adherence rate of microorganisms per unit volume of the carrier and a higher treatment capacity than the conventional microorganism-immobilized carrier.

The carrier for immobilizing microorganisms of the present invention has a high adherence rate of microorganisms, and is less likely to be separated from microorganisms due to the flow of sewage supplied into an aeration tank, and can stably retain microorganisms. And the processing time can be greatly reduced.

Further, since the microorganism-immobilized carrier of the present invention has good purification performance of the immobilized carrier itself, it is possible to reduce the shape of the immobilized carrier itself in a conventional device or to reduce the size of the device itself. Enables total cost reduction.

[0048]

EXAMPLES The present invention will be described below in detail with reference to Examples of the present invention, but the present invention is not limited to the following Examples.

EXAMPLE A predetermined amount of isocyanate, polyol, foaming agent and other additives were blended, and a flexible polyurethane foam of the same shape (length of one side: 1 cm, foam density: 0.025 g / cm ³ , air permeability: 250 cc / cm) ² / s
ec or more, and the number of cells was 13 / inch).

Next, each of the obtained foams was immersed in water prepared with a sulfosuccinic acid diester type surfactant (Sanmorin OT70 manufactured by Sanyo Chemical Co., Ltd.) at the concentration shown in Table 1 below, and the time required to sink under water was measured. did. The results are also shown in Table 1. The measurement period of the sinking time was one week.

[0051]

[Table 1]

From the results shown in Table 1, it was confirmed that the microorganism-immobilized carrier of the present invention was immersed faster as the surfactant was dispersed and mixed in the treated water.

[0053]

The carrier for immobilizing microorganisms of the present invention has a high rate of propagation of microorganisms, a large specific surface area, and good air permeability, so that it has a high treatment capacity and is extremely excellent in purification performance.

[Brief description of the drawings]

FIG. 1 is an embodiment showing a purification device of the present invention.

FIG. 2 is another embodiment showing the purification device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Purification apparatus 2 Aeration tank 3 Microorganism immobilization carrier 3a Microorganism immobilization carrier (fixed reef) 3b Microorganism immobilization carrier (flowing reef) 4 Aeration device 5 Inlet 11 Outlet

Claims (12)

[Claims] 1. A microorganism-immobilized carrier comprising microorganisms attached to and supported on a surface thereof, wherein the microorganism-immobilized carrier is formed of a flexible polyurethane foam without a cell membrane. 2. The polyurethane foam having an air permeability of 30 to 30.
^2. The microorganism-immobilized carrier according to claim 1, which has a flow rate of 400 cc / cm ² / sec. 3. The polyurethane foam having a density of 0.01
The microorganism-immobilized carrier according to claim 1, wherein the amount is 5 to 0.070 g / cm ³ . 4. The cell number of the polyurethane foam is 5-7.
The microorganism-immobilized carrier according to any one of claims 1 to 3, wherein the carrier is 0 / inch. 5. A polyurethane foam having a hardness of 5 to 30.
The microorganism-immobilized carrier according to any one of claims 1 to 4, wherein the carrier is kgf. 6. The microorganism-immobilized carrier has a side length of 4-5.
2. A cuboid or rectangular parallelepiped shape of 0 mm.
6. The microorganism-immobilized carrier according to any one of claims 1 to 5. 7. The microorganism-immobilized carrier according to any one of claims 1 to 6, wherein the microorganism-immobilized carrier is a flexible polyurethane foam having no cell membrane and a surfactant attached to a skeleton surface. 8. A microorganism-immobilized carrier having a surfactant adhered to its surface by immersing a flexible polyurethane foam having no cell membrane in water in which a surfactant is dispersed, squeezing the water and drying. The microorganism-immobilized carrier according to claim 7, which is: 9. By introducing sewage into an aeration tank containing a microorganism-immobilized carrier therein, and contacting the sewage with the microorganism-immobilized carrier while supplying air into the sewage.
9. A method for purifying sewage, wherein the microorganism-immobilized carrier is the microorganism-immobilized carrier according to any one of claims 1 to 8, wherein the microorganism-immobilized carrier is the microorganism-immobilized carrier. 10. The sewage purification method according to claim 9, wherein the sewage treatment is performed in the presence of a surfactant. 11. A purifying apparatus comprising an aeration tank containing an aeration apparatus and a microorganism-immobilized carrier, wherein the microorganism-immobilized carrier is the microorganism-immobilized carrier according to any one of claims 1 to 8. A purifying device, comprising: 12. The purification apparatus according to claim 11, wherein the microorganism-immobilized carrier is a fixed reef or a fluid reef.