JP2001211881A - Method for producing carrier for microorganism, carrier for microorganism, and septic tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a carrier for microorganisms, durable for a long application, hardly deformed and hardly increasing in flow resistance caused by compaction of a fixed bed filled with the carrier. SOLUTION: This carrier for microorganisms comprises a substrate resin having a melting point of P1, a foaming agent and a fiber having a melting point or heat-deformation temperature (P2) higher than P1 as raw materials and is produced by fusing and kneading them at a temperature of >=P1 but <P2 and forming with heating and foaming at a temperature of >=P1 but <P2. A curing agent is preferably used other than the substrate, the foaming agent and the fiber and a cut fiber having 0.1-2.0 mm length is preferably used as the fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a microorganism carrier used in a sewage treatment tank for biologically treating wastewater (sewage) such as domestic wastewater or organic industrial wastewater discharged from a household, a microorganism carrier, and a microorganism carrier. It relates to a sewage septic tank.

[0002]

2. Description of the Related Art When biological wastewater such as domestic household wastewater or organic industrial wastewater is biologically treated in a sewage treatment tank, microorganisms such as activated sludge are used as microorganism carriers (became a home for microorganisms. A sewage purification tank is widely used in which wastewater is attached to microbial adhering bodies and treated by contacting wastewater with the wastewater. Conventionally, various carriers have been known as microorganism carriers, and examples thereof include sponge-like polyethylene communicating cells.

[0003]

The above-mentioned sponge-like polyethylene open-cell foam is suitable as a habitat for microorganisms or as a filter material for suspended solids (SS), but it becomes one of the problems with long-term use. There is also a drawback that the part is deformed and the fixed bed filled with the part is densified to increase water flow resistance.
An object of the present invention is to provide a microbial carrier that is resistant to deformation for a long period of time and is less likely to be deformed or to have a compacted bed filled with the same, thereby reducing water flow resistance.

[0004]

In order to achieve the above object, the present invention has the following arrangement. That is, the present invention uses, as raw materials, a base resin having a melting point P ₁ , a foaming agent, and a fiber having a melting point or heat deformation temperature P ₂ higher than P ₁ .
These were melt-kneaded at a temperature of less than P ₁ or P _2, a further method for producing a microorganism carrier, which comprises molding while heating and foaming at a temperature of less than P ₁ or P _2. The above P ₂
If with fibers pyrolyzed at temperatures, this temperature P ₂ is consistent with the thermal decomposition temperature of the fiber. In the above production method, a crosslinking agent is preferably used in addition to the base resin, the foaming agent and the fiber. Further, the fiber is preferably 0.1 m in length.
A cut fiber of m to 2.0 mm is used.

[0005] The present invention also relates to a microorganism carrier,
A porous resin having a melting point P _1, to the microorganism carrier having a melting point or heat distortion temperature comprising a fiber having a high temperature P ₂ than the P ₁ relates. Here, a porous resin having a melting point P ₁ is preferably an expansion ratio (volume of the resin itself other than the holes of the total volume / porous resin of pores comprises a porous resin) 5-25
It is twice as open-celled. This is because, in the case of interconnected foams (foams) in which the walls of the bubbles (cells) are broken and the cells communicate with each other, drainage containing organic matter, microorganisms, and the like can enter the inside.

The present invention further relates to a sewage treatment tank provided with a microorganism carrier in the tank. As the sewage purification tank, there is, in order from the upstream, a sewage purification tank having an anaerobic filter bed tank, an aerobic filter bed tank, a treatment water tank, a disinfecting tank, and the like. A carrier can be filled.

[0007]

When producing the microorganism carrier of the present invention, a raw material containing a base resin (its melting point: P ₁ ), a foaming agent and fibers (its melting point or heat deformation temperature: P ₂ ) is mixed with P ₁ or more and P ₂ When the heating is performed at a temperature lower than the above, the base resin is liquefied, but the fiber is not liquefied and remains as a solid (fiber). Therefore, the obtained microorganism carrier (foam) contains fibers, and the mechanical strength is increased by the action of the fibers.

[0008]

First, a method for producing a microorganism carrier will be described. (1) Base resin The base resin which is the main raw material of the porous resin includes thermoplastic resins such as polyvinyl chloride, polyvinyl formal, polyethylene, polypropylene, ethylene vinyl acetate, ethylene vinyl acetate copolymer, and polystyrene. is there.

(2) Foaming agent In the production of the microbial carrier of the present invention, in addition to the base resin, a necessary agent is a foaming agent. In addition to the foaming agent,
If necessary, a foaming aid, a foam breaking agent, or the like is used.

Examples of the foaming agent include azo compounds such as azodicarbonamide and barium azodicarboxylate; nitroso compounds such as dinitrosopentamethylenetetramine and trinitrosotrimethyltriamine;
There are hydrazide compounds such as p'-oxybisbenzenesulfonyl hydrazide and sulfonyl semicarbazide compounds such as p, p'-oxybisbenzenesulfonyl semicarbazide and toluenesulfonyl semicarbazide.

Examples of the foaming aid include compounds mainly containing urea, metal oxides such as basic zinc carbonate, zinc oxide and lead oxide, compounds mainly containing salicylic acid, stearic acid and the like. .

[0012] Examples of the foam breaking agent include, for example, inorganic powders such as talc and the like, and needles such as whisker and mill fiber.

(3) Other raw materials related to formation of porous resin Other raw materials related to formation of porous resin include a cross-linking agent, a cross-linking assistant, an antioxidant, a filler and the like. It is used as needed according to the type of the base resin.

Examples of the crosslinking agent (including a radical generator) include dicumyl peroxide, 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane,
5-dimethyl-2,5-di-t-butylperoxyhexane, t-butylperoxyketone or t-butylperoxybenzoate.

Examples of the crosslinking assistant include quinone dioxime, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate and the like.

The antioxidants include, for example, 2,6-di-o-butyl-4-methylphenol, n-octadecyl-
Phenolic compounds such as 3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate, dilauryl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate And sulfur-based compounds such as trisnolylphenyl phosphate and distearylpentaerythritol diphosphate.

The filler includes, for example, carbon black,
Examples include powders of zinc oxide, silicon oxide, magnesium carbonate, calcium carbonate, calcium sulfate, barium sulfate, zeolite and the like. When a filler is used, it is used in a range that does not adversely affect cross-linking, foamability, strength after foaming, and the like.

(4) Fibers whose melting point or thermal deformation temperature is higher than the melting point of the base resin The fibers whose melting point is higher than the melting point of the base resin include polyester fiber, acrylic fiber, nylon fiber, vinylon fiber and polyethylene fiber. And synthetic fibers such as polypropylene fibers and vinylidene fibers. Examples of the fibers having a heat deformation temperature higher than the melting point of the base resin include inorganic fibers such as carbon fibers and glass fibers, and vegetable fibers such as cotton fibers and processed cotton fibers. Among them, synthetic fibers are preferred from the viewpoint of durability (including microbial resistance) and cost. The fiber (length) is 0.1% from the point of foaming of the resin.
A cut fiber of about 2 mm is preferred.

When a low-density polyethylene (melting point: 106 to 115 ° C.), ethylene vinyl acetate copolymer (melting point: 103 to 108 ° C.) or polypropylene (melting point: about 168 ° C.) is used as the resin substrate of the porous resin, for example, Fibers having a melting point higher than this melting point are selected from synthetic fibers such as polyester fibers (melting point: 254 to 255 ° C), nylon fibers (nylon 6, melting point: 210 to 220 ° C), vinylon fibers (melting point: 230 to 250 ° C), and the like. Can be.

The specific gravity of the fiber used is preferably larger than 1. The optimum specific gravity of the microorganism carrier is slightly different depending on whether it is for a fluidized bed or a fixed bed, but most of them are generally 1. Most of the thermoplastic resins have a specific gravity of less than 1 (for example, about 0.94 for polyethylene and about 0.93 for polypropylene).
This is because the specific gravity of the fiber to be used must be larger than 1. For example, polyester fiber has a specific gravity of about 1.38, nylon fiber has a specific gravity of about 1.14, vinylon fiber has a specific gravity of about 1.26, and vinylidene fiber has a specific gravity of about 1.7. By using these fibers, the specific gravity of the obtained microorganism carrier (whole) is adjusted.

(5) Melting / kneading / foaming / molding The above materials are mixed, and the melting point of the fiber is lower than the decomposition temperature of the crosslinking agent and lower than the decomposition temperature of the foaming agent, and is higher than the melting point (P ₁ ) of the base resin. At a temperature lower than the heat distortion temperature (P ₂ ), melt using a Banbury mixer, roll, extruder, etc.
Knead. Thereafter, this is usually made into pellets.

The pellets are continuously formed into a sheet shape through a die, for example, or are poured into a non-closed mold to be formed discontinuously. In the case where the foam is continuously formed into a sheet, the foamed sheet can be obtained by placing it in a hot-air high-temperature furnace together with the carrier, heating and foaming the foam, and then rapidly cooling the foam. The foam sheet obtained by such a method can be a continuous foam in which the cells are broken at the time of foaming and the cells are connected depending on the composition ratio of the composition and the like.

In the case of non-continuous molding, for example, the above-mentioned pellets are injected into a non-closed mold while heating and softening, and then molded, then placed in a high-temperature metal bath and foamed. In a high-temperature metal bath that is hotter than the one, it is subjected to secondary foaming, then cooled, passed through between two rolls, and the bubbles are broken by the pressing of the rolls. You can get the body. The foam obtained by this method usually has a higher open cell ratio than the foam obtained by the above method.

[0024] The foam obtained in this way is intended for the purpose (filter material, contact material or biological reaction) and the place of application (anaerobic filter bed or aerobic filter bed, fixed bed or fluidized bed). According to the conditions and the like, it is appropriately cut into an optimum shape and dimensions. The shape includes a columnar shape, a prismatic shape (square shape, polygonal shape), a hollow shape thereof, and the like. For example, in the fluidized bed, from the viewpoint of fluidizing the microorganism carrier, the diameter of the cross section or one side of the cross section is approximately 5 mm to 20 mm, and the length is also approximately 5 mm to 2 mm.
Those having a thickness of about 0 mm are used. Further, in the case of a fixed bed, when a contact material that also has a filtering function is used, the diameter of the cross section or one side of the cross section is approximately 5 mm to 20 mm, and the length is approximately 5 mm.
When the contact material is used (for biological reaction), the diameter of the cross section or one side of the cross section is approximately 5 mm to 2 mm.
One having a length of about 0 mm and a length of about 500 to 2000 mm is used.

FIG. 1 is an example of a sewage purification tank (schematic sectional view) in which the microorganism carrier of the present invention is provided in a tank. The sewage purification tank 21 is disposed in the order of an anaerobic filter bed tank (first chamber) 22, an anaerobic filter bed tank (second chamber) 23, an aerobic filter bed tank 24, a treatment water tank 25, and a disinfection tank 26 from the upstream side. I have. Sewage purification tank 2
1 is a blower 2 for sending air to the aerobic filter bed tank 24 and the like.
7 are provided. The aerobic filter bed tank 24 is provided with an air diffuser 28 and a sludge discharge member 29 below the filter bed, and a return pipe 30 is connected to the sludge discharge member 29.

Instead of the anaerobic filter tank (first chamber) 22 and the anaerobic filter tank (second chamber) 23, only a sedimentation separation tank may be provided. May be provided. Further, a sedimentation tank may be provided instead of the treatment water tank 25. Also, a manhole and a manhole cover 31 for closing the manhole are provided so that the inside of each tank can be inspected from above.

The microorganism carrier of the present invention comprises an anaerobic filter tank (first chamber) 22, an anaerobic filter tank (second chamber) 23 and an aerobic filter tank 2.
No. 4, or all of them may be filled. The filter bed of the anaerobic filter tank (first chamber) 22, the anaerobic filter tank (second chamber) 23, or the aerobic filter tank 24 may be a fixed bed or a fluidized bed. Anaerobic or aerobic filter bed
Alternatively, it is appropriately determined depending on whether it is a fluidized bed or a fixed bed.

In the sewage purifying tank 21, the waste water is treated as follows. First, the wastewater enters the upper part of the anaerobic filter bed tank (first chamber) 22 from the inflow port 32 and flows downward to the lower part of the tank.
At this time, the anaerobic filter bed (first chamber) 22 has an anaerobic filter bed 33.
During the passage through the anaerobic filter bed 33, the organic matter is decomposed by the anaerobic microorganisms attached to the anaerobic filter bed 33, and the solid matter precipitates near the lower part of the tank. Anaerobic filter bed tank (first room)
The wastewater treated in 22 passes from the lower part of the anaerobic filter bed 33 to the upper part of the anaerobic filter tank (second chamber) 23 through the advection part, and flows downward to the lower part of the tank. At this time, in the anaerobic filter bed tank (second chamber) 23, while passing through the anaerobic filter bed 34, further solid substances are captured and organic substances are decomposed by anaerobic microorganisms, and solid substances precipitate near the lower part of the tank.

The wastewater treated in the anaerobic filter bed (second chamber) 23 passes through the advection section from below the anaerobic filter bed 34 and enters above the aerobic filter tank 24. In the aerobic filter bed tank 24, the air sent from the blower 27 is used to maintain the aerobic state.
8 is discharged. The water flows downward to the bottom of the tank. At this time, while passing through the aerobic filter bed 35, solid matter adheres (or is trapped) and decomposition of organic matter by the aerobic microorganisms adhering to the aerobic filter bed 35 proceeds. The aerobic filter bed 35 of the aerobic filter bed tank 24 is filled with a microbial carrier, whereby organic matter is efficiently decomposed.

The waste water treated in the aerobic filter bed tank 24 enters a treated water tank 25 as treated water, and reaches a disinfecting tank 26 provided above the treated water tank 25. The treated water disinfected in the disinfection tank 26 is discharged from the discharge port 21 to the outside of the sewage purification tank 21.

[0031]

EXAMPLE 1 A resin base material was a mixture of low-density polyethylene (melting point: about 110 ° C.) and ethylene vinyl acetate copolymer (melting point: about 80 ° C.), and a fiber was a polyester fiber (melting point: about 255 ° C., fiber diameter) Cut fiber having a fiber length of about 55 μm and a fiber length of about 0.5 to 1 mm), dicumyl peroxide as a crosslinking agent, azodicarbonamide as a foaming agent, and zinc stearate as a foaming aid, and the above-mentioned discontinuous molding is produced. By the method, about 5 L of a porous resin composed of open cells was obtained. The amount of the polyester fiber used is determined by the resin base material 10
It is 10 parts by weight with respect to 0 parts by weight. As a control, a porous resin produced by the same method without adding a polyester fiber was used.

(Evaluation Test) Each of the communicating foam blocks was cut to obtain a large number of cubic microorganism carriers each having a side of 12 mm. Using this cube as a sample, 5
The stress at the time of 0% (height) compression was measured. As a result, the microbial carrier of the present invention was 35,000 Pa, and the comparative product was 1
It was 0000 Pa. The microbial carrier of the present invention clearly had higher compressive strength.

[0033]

According to the production method of the present invention, a microbial carrier that can withstand long-term use and is less likely to be deformed or to have a fixed bed filled with the same compacted to increase the water flow resistance. It can be easily manufactured. 2) Since the microbial carrier of the present invention has the porous resin reinforced by the fiber, the mechanical strength is increased and the microbial carrier is not easily deformed. Also, the durability is improved. Furthermore, when the porous resin is a continuous foam, the microorganisms can live in the inside of the microorganism carrier, so that the microorganism carrier having a high drainage treatment function can be obtained. 3) Since the sewage purification tank of the present invention is provided with a microorganism carrier which is strong in external force and can attach a large amount of microorganisms in the tank, wastewater can be treated stably.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an example of a sewage treatment tank according to the present invention.

[Explanation of symbols]

 21: Sewage purification tank 22: Anaerobic filter bed tank 23: Anaerobic filter bed tank 24: Aerobic filter bed tank 25: Treated water tank 26: Disinfection tank 27: Blower 28: Air diffuser 29: Sludge discharge member 30: Return pipe 31: Manhole cover 32: Inlet 33: Anaerobic filter 34: Anaerobic filter 35: Aerobic filter 36: Outlet

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C12N 1/20 B29K 105: 04 B29K 105: 04 105: 12 105: 12 B29C 67/22 (72) Inventor Shinji Fujita 1250 Shimoedori, Shimodate-shi, Ibaraki Pref.Hitachi Chemical Industry Co., Ltd.Yuki Works (72) Inventor Kozo Ashizawa 1250 Shimoe-ren, Shimodate-shi Ibaraki Pref. 4B033 NA11 NB02 NB68 ND20 NF06 4B065 AA01X BC42 CA54 4D003 AA01 AA12 AB02 BA02 CA02 CA08 EA07 EA14 EA19 EA26 EA30 EA38 FA10 4D027 AB07 4F212 AA03 AA13 AA15 AB03 AB25 AG20 AH81 UA01 UA01

Claims (6)

[Claims] _1. A base resin having a melting point P ₁ , a foaming agent, and the P ₁
And fibers of high melting point or heat distortion temperature P ₂ than as a raw material, melting and kneading them at a temperature below P ₁ or P _2,
Further shaping while heating and foaming at a temperature of less than P ₁ or P _2, the microbial carrier preparation. 2. The method according to claim 1, wherein a crosslinking agent is further used as a raw material in addition to the base resin, the foaming agent and the fiber. 3. The fiber has a length of 0.1 mm to 2.0 mm.
The production method according to claim 1 or 2, wherein a cut fiber is used. 4. A microorganism carrier comprising a porous resin having a melting point P _1, the fiber is a high temperature P ₂ than the melting point or heat distortion temperature of the P _1. 5. The microorganism carrier according to claim 4, wherein the porous resin is a continuous foam having an expansion ratio of 5 to 25 times. 6. A sewage purification tank provided with the microorganism carrier according to claim 4 in a tank.