JP2001231554A - Microorganism carrier reinforced covering material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a carrier for microorganisms capable of being resistant to be used for a long time and being hardly deformed and increasing water flow resistance of a fixed bed filled with the carrier caused by compaction of the fixed bed and provide a method for producing the same. SOLUTION: This method for producing a carrier for microorganisms is to heat a main resin material containing a thermoplastic resin at a temperature equal to or higher than its softening point to melt and knead by extruder, inject a foaming agent and further knead and foam the kneaded mixture by extruding the mixture from a die, subsequently pre-heat the extruded foam from the die, while extrude the raw material of a coating material from another extruder to pass through a coating apparatus and form a coating material 3 on the outer surface of the foam, and cut the obtained rod-like product in a predetermined length to obtain the carrier for microorganisms. Further, a sewage purification tank installed with the aforesaid microorganism carrier is claimed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a microorganism carrier reinforced with a covering material. More specifically, the present invention relates to a microorganism carrier suitably used for a sewage purification tank for biologically treating wastewater (sewage) such as domestic wastewater or organic industrial wastewater discharged from homes, a method for producing the same, and a sewage purification tank.

[0002]

2. Description of the Related Art When biological wastewater (sewage) such as domestic wastewater or organic industrial wastewater discharged from a household is biologically treated in a sewage treatment tank, microorganisms such as activated sludge become microorganism carriers (houses of microorganisms). A biological treatment method in which wastewater is adhered to a contact material, a filter material, and a microorganism-attached body) and treated by bringing wastewater into contact therewith, and a sewage purification tank therefor are widely used. As the microorganism carrier, various carriers have been conventionally known, 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). 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.
The present invention provides a microbial carrier that can withstand long-term use, is less deformed, and does not increase the water flow resistance due to compaction of a fixed bed filled with the same, a method for producing the same, and a sewage purification tank to which the microorganism carrier is applied. That is the task.

[0004]

In order to achieve the above object, the microorganism carrier of the present invention has the following constitution. That is, the microorganism carrier of the present invention is a microorganism carrier 1 comprising a porous resin 2 and a coating material 3 formed on a part of the surface of the porous resin.

The shape of the porous resin 2 (or the microorganism carrier 1) can be cylindrical, prismatic, polygonal, star-shaped, cylindrical, or various shapes similar thereto, but is preferable in view of ease of production. The shape is a substantially cylindrical shape (including a true circular shape) or a substantially cylindrical shape having a hollow core.

Here, the coating material 3 has the purpose of reinforcing the porous resin 2 and, instead of covering the entire surface of the porous resin 2, prevents the drainage and microorganisms from entering the inside. 2 to cover a part of the surface. One preferable coating form of the coating material 3 is to cover the outer curved surface (excluding the upper surface and the lower surface) of the substantially cylindrical column when the shape of the porous resin 2 is a substantially cylindrical column. Another preferred form of coating of the coating material 3 is to cover the hollow inner curved surface when the porous resin 2 is a substantially cylindrical column having a hollow core.

[0007] The coating material 3 has a thickness of 0.05 to 1.0 mm (more preferably, 0.1 mm to 0.5 mm).
The shape of the coating material 3 may be a corrugated shape (corrugated shape), a sheet shape having projections, a net shape, or the like, in addition to a flat shape. When the covering material 3 covers the outer curved surface of the porous resin 2, in order to further improve the strength and the microbial adhesion of the microorganism carrier 1, the thickness is about 0.2 to 2.0 mm and the length is 1.0 to 3.0.
An outwardly extending projection 4 of about mm may be provided. In the case where the core of the porous resin 2 has a cavity and the coating material 3 is provided on the inner curved surface on the cavity side of the core, the projection 4 can be provided on the curved surface on the cavity side. The shape of the projection 4 may be continuous or discontinuous in the axial direction of the cylinder or in the circumferential direction of the cylinder. The protrusions 4 may be provided continuously or discontinuously in a lattice shape.

Here, the porous resin 2 is a foam having an expansion ratio (total volume of the porous resin including bubbles / volume of the resin itself other than the bubbles in the porous resin) of about 5 to 25 times. The bubbles (cells) are preferably open-cell foams, each of which communicates. In order to allow wastewater or microorganisms containing organic matter to enter the interior, it is more preferable to use open-cell foams in which cells communicate with each other than closed cells (foams) in which cells are independent. is there.

The present invention also relates to a method for producing these microbial carriers, that is, a resin material containing a thermoplastic resin, a foaming agent and a foam control agent is extruded and foamed using an extruder, and a coating material is formed around the resin material. The present invention also relates to a method for producing a microorganism carrier, which comprises bonding the obtained rod-shaped material to a predetermined length.

[0010] The present invention further relates to a sewage purification tank provided with the above-mentioned microorganism carrier in a tank, for example, a sewage purification tank having an anaerobic filter bed tank, an aerobic filter bed tank, a treatment water tank, a disinfection tank and the like in order from the upstream. The present invention also relates to a sewage purification tank in which the microorganism carrier is filled in the anaerobic or aerobic filter tank.

[0011]

When the outer curved surface excluding the upper and lower surfaces of the substantially cylindrical porous resin 2 is covered with the covering material 3, the microorganism carrier 1 reinforced with the covering material 3 is not easily deformed. Similarly, when the outer curved surface or the inner curved surface of the substantially cylindrical porous resin 2 having a hollow core portion is reinforced by the covering material 3, the microorganism carrier 1 is similarly difficult to deform.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described more specifically with reference to the accompanying drawings. First, the method for producing the microorganism carrier of the present invention will be described with reference to FIGS. In one method, as shown in FIG. 1, first, a resin main material 5 composed of a thermoplastic resin and a cell regulator is charged into a hopper 6, and extruded at a temperature not lower than the softening point of the thermoplastic resin. The mixture is kneaded and melted by an extruder 7, a blowing agent 9 is injected from a blowing agent injection device 8 provided in the middle of the extruder 7, further kneaded, and extruded from a die 10 into a low-pressure region to be foamed. 2.) Get 2. Thereafter, the porous resin 2 sent out from the die 10 is preheated, and the coating material 14 is extruded from another extruder 11 and passed through the coating device 15 to form the coating material 3 on the outer surface of the porous resin 2. Let it. In this case, the thickness of the coating material 3 can be freely adjusted by adjusting the passage speed of the porous resin 2 in the coating device 15. The coating material 3 becomes thinner when the passing speed is increased, and becomes thicker when the passing speed is decreased. The obtained rod-shaped material may be cut into a predetermined length. This production method is used for producing a microorganism carrier as shown in FIG. 4 described below.

Another method is the manufacturing method shown in FIG. In the same manner as described above, the coating material is extruded from the die 10 of the extruder 7 and foamed at the same speed as the feeding speed of the porous resin 2 from the inlet side of the welding device 12 having a flat inlet side and a cylindrical outlet side. Then, the coating material 3 is coated and formed on the outer curved surface of the porous resin 2 by the welding device 12. In addition, in the welding device 12, the porous resin 2 is formed using an adhesive or the like.
And the coating material 3 can be bonded to each other, but heat welding is preferable in consideration of productivity. The obtained rod-shaped material may be cut into a predetermined length. This manufacturing method is described in FIGS.
It is used for the production of a microorganism carrier as shown in FIGS.

Among the resin materials used herein, thermoplastic resins include polyvinyl chloride, polyvinyl formal, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, and ethylene-propylene-diene copolymer. There are thermoplastic resins such as a polymer, an ethylene-methacrylic acid copolymer, and polystyrene and a mixture thereof, and preferably, a polyethylene, an ethylene-vinyl acetate copolymer and a mixture thereof.

Examples of the foaming agent include gases such as nitrogen gas, carbon dioxide gas, hydrocarbon gas, halogenated hydrocarbon and volatile foaming agent, and azo compounds such as azodicarbonamide and barium azodicarboxylate. Nitroso compounds such as nitrosopentamethylenetetramine and trinitrosotrimethyltriamine, hydrazide compounds such as p, p'-oxybisbenzenesulfonylhydrazide,
Solid substances such as sulfonyl semicarbazide compounds such as p, p'-oxybisbenzenesulfonyl semicarbazide and toluenesulfonyl semicarbazide can be used. As the cell adjusting material, a nucleating agent such as calcium carbonate and talc, an anti-shrinkage agent for suppressing dimensional shrinkage during extrusion foaming, an antioxidant, an antistatic agent, a pigment, a filler and the like can be used.

Examples of the coating material include polyvinyl chloride, polyvinyl formal, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, and ethylene-methacrylic acid copolymer. A film or sheet of a thermoplastic resin such as coalesced, polystyrene, acrylic resin, nylon, polycarbonate and polyethylene terephthalate is used.

The above resin material is extruded from an extruder adjusted to a temperature equal to or higher than the softening point of the thermoplastic resin, and the expansion ratio of the foamed porous resin is adjusted to be about 5 to 25 times.

The specific gravity of the produced microorganism carrier is adjusted according to the form of use. For example, when a microorganism carrier is used as a fluidized bed in a biological reaction, the specific gravity is preferably set to 0.95 so that the biological reaction occurs while the microorganism carrier flows.
１．０1.05. When the flow of the waste water is used as a downward flow and the microorganism carrier is also used as a filtering material, the specific gravity is preferably set to 1.05 to 1.20 in order to ensure good filtration efficiency and good washing efficiency. I do. In addition, when using the microorganism carrier as a filtering material with the flow of the wastewater as the upward flow,
The specific gravity is preferably set to 0.60 to 0.95 in order to ensure that the captured SS is not easily peeled off and secure good cleaning efficiency.

The specific gravity of the microorganism carrier can be adjusted by selecting a porous resin (selecting various porosity), selecting a material for the coating material, or adjusting the volume ratio of both. In addition, both or one of the porous resin and the coating material is mixed with an inorganic solid such as calcium carbonate, barium sulfate, magnesium sulfate, talc, aluminum oxide, silicon dioxide, zeolite, or activated carbon, and then molded to obtain a specific gravity. Can be raised. However, if an inorganic solid is excessively mixed in the porous resin, the properties such as continuity, porosity and durability of the microorganism carrier are impaired. In order to avoid this, it is more preferable to mix in the coating material than to mix in the porous resin.

FIG. 3 shows another method for producing the microorganism carrier of the present invention. A sheet in which the porous resin sheet 2 sliced to an arbitrary thickness and the covering material 3 are bonded or welded in advance is fed into a welding device 13 having a flat entrance side and a cylindrical exit side, and the mating surface (X , Y). As shown in FIG. 3A, when the coating material 3 is located above the porous resin sheet 2, the microorganism carrier 1 having the coating material 3 on the inner curved surface of the substantially cylindrical body as shown in FIG. Can be. When the coating material 3 is located below the porous resin sheet 2 as shown in FIG. 3B, the microorganism carrier 1 having the coating material 3 on the outer curved surface of the substantially cylindrical body as shown in FIG. Can be. In the welding device 13, the mating surfaces (X,
Y) can be bonded with an adhesive or the like, but heat welding is preferred in view of productivity. The obtained rod-shaped material may be cut into a predetermined length. This production method is used for producing a microorganism carrier as shown in FIGS. 7 to 11 described below.

In the case of using a sheet in which the covering material 3 is bonded to the porous resin sheet 2 in advance as in the above example, the covering material 3 may be a corrugated (corrugated) or projection-like material, or a net-like material. Can be used. Further, the coating material 3 can be formed in a corrugated shape (corrugated shape) by a coating device or a welding device, or a projection can be formed thereon.

The following is a brief description of some examples of the microorganism carrier thus produced, with reference to FIGS. FIG. 4 shows a microorganism carrier 1 in which a sheet-like covering material 3 is adhered to an outer curved surface (excluding an upper surface and a lower surface) of a substantially cylindrical porous resin 2. In the case of a substantially columnar shape, the size is preferably such that the height (H) of the column is about 5 to 20 mm and the diameter (D) of the column is about 5 to 20 mm.

FIG. 5 shows the sheet-like covering material 3 in FIG.
Instead of the microbial carrier 1 to which a net-like coating material 3 is adhered.

FIG. 6 shows the microorganism carrier 1 in which the covering material 3 is a corrugated (corrugated) sheet.

FIG. 7 shows a microorganism carrier 1 similar to the microorganism carrier 1 shown in FIG. 6, the core of which is hollow. When the core is a hollow cylindrical body (that is, a cylindrical shape), the diameter (d) of the hollow is preferably about 2 to 8 mm.

FIG. 8 shows a microorganism carrier 1 in which a corrugated covering material 3 covers the inner curved surface of a hollow column (not the outer curved surface) of a hollow column.

FIG. 9 shows a microorganism carrier 1 in which a coating material 3 having projections 4 in the axial direction on the outer curved surface of a cylindrical porous resin 2 is covered.

FIG. 10 shows a microorganism carrier similar to the microorganism carrier shown in FIG. 9, wherein the microorganism carrier 1 is covered with a coating material 3 having projections 4 on the outer curved surface in the circumferential direction.

FIG. 11 shows a microorganism carrier similar to the microorganism carrier shown in FIG. 9, in which the cylindrical inner surface of the porous resin 2 is covered with the coating material 3 having the projections 4.

FIG. 12 shows an example of a sewage purification tank provided with the above-described microorganism carrier in the tank. The sewage septic tank 21
From the upstream side, 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 are arranged in this order. In the sewage septic tank 21,
A blower 27 for sending air to the aerobic filter bed tank 24 and the like is provided. The aerobic filter bed tank 24 is provided with an air diffusion member 28 and a sludge discharge member 29 below the filter bed.
9, a return pipe 30 is connected and arranged.

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.

[0036]

Example 1 The microorganism carrier shown in FIG. 4 was produced by the production method shown in FIG. Low density polyethylene (Mitsubishi Yuka Co., Ltd. Yucalon LK-80, MFR4, density 0.918 g / cubic cm)
100 parts by weight, 1.0 part by weight of talc, and 1.2 parts by weight of amide are mixed, supplied to an extruder having a diameter of 40 mm, melt-kneaded, and supplied to a foaming agent inlet provided near the tip of the extruder. 1,1,1,2-tetrafluoroethane (HFC-
134a) was injected, kneaded and gelled, and extruded from the die into the atmosphere. After preheating at 100 ° C., low-density polyethylene (same as above) heated to below the softening point is heat-welded to the outer surface of the porous resin by a heat-welding apparatus, and the length is 10 mm.
mm. The resulting microorganism adherent is 10 m long
m, a substantially cylindrical body having a diameter of 10 mm, and a coating material having a thickness of 0.5 mm was covered on the outer surface of a porous resin having a foaming ratio of 20 times.

(Evaluation Test) When the compressive strength (50% compressive stress) of the microbial carrier thus obtained was measured, it was 7
It was 5,000 Pa. As a comparative control, the measurement of a polyethylene open-cell foam of the same shape without a coating material (specific gravity: 1.05) was 11,000 Pa, which was about seven times that.

[0038]

(1) The microbial carrier of the present invention 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 resistance to water flow. Moreover, since it is not easily deformed, a large amount of microorganisms can be attached. (2) According to the production method of the present invention, it can withstand long-term use,
It is possible to produce a microbial carrier that is less likely to be deformed or to have a fixed bed filled with the same compacted to increase the water flow resistance. (3) According to the sewage purification tank of the present invention, the fixed bed is less likely to be compacted and the water flow resistance is increased. Further, the wastewater can be stably treated for a long time.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a first method for producing a microorganism carrier of the present invention.

FIG. 2 is a schematic diagram showing a second method for producing a microorganism carrier of the present invention.

FIG. 3 is a schematic diagram showing a third method for producing a microorganism carrier of the present invention.

FIG. 4 is a perspective view of the microorganism carrier according to the first embodiment of the present invention, and FIG. The coating is a flat, non-porous sheet.

5 (a) is a perspective view and FIG. 5 (b) is a front view of the microorganism carrier according to the second embodiment of the present invention. The covering is a mesh sheet.

FIG. 6 shows a microorganism carrier according to a third embodiment of the present invention, wherein (a) is a perspective view and (b) is a front view. The covering material is a non-porous corrugated sheet.

FIG. 7 shows a microorganism carrier according to a fourth embodiment of the present invention, wherein (a) is a perspective view and (b) is a front view. The core is hollow.

8 (a) is a perspective view and FIG. 8 (b) is a front view of a microorganism carrier according to a fifth embodiment of the present invention. The core covers the inner curved surface of the hollow cylinder with the covering material.

FIG. 9 shows a microorganism carrier according to a sixth embodiment of the present invention, wherein (a) is a perspective view and (b) is a front view. The core has an outer curved surface of a hollow cylinder covered with a coating material having an axially continuous projection.

FIG. 10 shows a microorganism carrier according to a seventh embodiment of the present invention, wherein (a)
Is a perspective view, and (b) is a front view. The outer surface of the hollow cylindrical column is covered with a covering material having projections continuous in the circumferential direction.

FIG. 11 shows a microbial carrier according to an eighth embodiment of the present invention, wherein (a)
Is a perspective view, and (b) is a front view. The core has an inner curved surface of a hollow cylinder covered with a coating material having an axially continuous projection.

FIG. 12 is a schematic sectional view of a sewage treatment tank according to an example of the present invention.

[Explanation of symbols]

 1: Microbial carrier 2: Porous resin 3: Coating material 4: Projection 5: Resin material 6: Hopper 7: Extruder 8: Foaming agent injection device 9: Foaming agent 10: Die 11: Extruder 12: Welding device 13: Coating device 14: Coating material raw material 21: Sewage purification tank 22: Anaerobic filter bed tank 23: Anaerobic filter bed tank 24: Aerobic filter bed tank 25: Treatment 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: Discharge port

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) C08J 9/04 103 C08J 9/04 103 4F074 9/10 CER 9/10 CER 9/12 CER 9/12 CER 9/38 CER 9/38 CER C12M 1/40 C12M 1/40 Z E03F 5/14 E03F 5/14 // C08L 101: 00 C08L 101: 00 (72) Inventor Kozo Ashizawa 1250 Shimoedori, Shimoeda, Shimodate City, Ibaraki Prefecture Hitachi (72) Inventor Nobuyoshi Katagai 1250, Shimoe-ren, Shimodate-shi, Ibaraki Pref.Hitachi Chemical Industry Co., Ltd.Yuki Office F-term (reference) NB02 NB12 NB15 NB34 NB35 NC04 ND04 ND20 NE10 4D003 AA01 AA12 BA01 CA08 EA20 EA30 EA38 4D027 AB07 4F074 AA17 AA22 AA24 AA32 AA35 AA44 CE13 CE15 CE16 CE32 CE32 CE48 CE98 DA02 DA08 DA12 DA13 DA14 DA59

Claims (7)

[Claims] 1. A microorganism carrier comprising a porous resin and a coating material formed on a part of the surface of the porous resin. 2. The microorganism carrier according to claim 1, wherein the shape of the porous resin is substantially a column, and the covering material is formed to cover an outer curved surface of the substantially column. 3. The microorganism carrier according to claim 2, wherein the core of the substantially cylindrical porous resin is hollow. 4. The microorganism according to claim 1, wherein the shape of the porous resin is substantially a column, the core of the substantially column is a hollow, and the coating material is formed to cover the hollow inner curved surface. Carrier. 5. The microbial carrier according to claim 1, wherein the porous resin is a foam having an expansion ratio of 5 to 25, and cells (cells) in the foam communicate with each other. 6. A method for producing a microorganism carrier, wherein the porous resin has a substantially cylindrical shape, and the covering material is formed by covering an outer curved surface of the substantially cylindrical shape. While extruding and foaming a resin material containing
A method for producing a microorganism carrier, comprising: adhering a coating material to the periphery thereof; and cutting the obtained rod-shaped material into a predetermined length. 7. A sewage purification tank comprising the microorganism carrier according to claim 1 in a tank.