JPH10174989A - Wastewater treatment method and microbe carrier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide desiring shape of a microbe carrier made of a plastic to be used for a fluidized bed type biological wastewater treatment apparatus and provide a biological wastewater treatment method for which the microbe carrier is employed. SOLUTION: A microbe carrier 13 made of a hollow tubular plastic having the relation: outer diameter >= the tubular length: is used for a fluidized bed type biological wastewater treatment apparatus. The cross-section shape of the microbe carrier 13 is not restricted only to be circular but may be elliptical and rectangular. The desirable size of the microbe carrier is 1-10mm of both outer diameter and tubular length and the absolute specific gravity of the carrier is 0.8-1.5. In this fluidized bed type biological wastewater treatment apparatus, the treated water and the carrier can be efficiently separated from each other by a separator such as slits 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is mainly used for a fluidized-bed biological treatment apparatus, and is used for biodegradation by attaching microorganisms to the surface thereof, biodegradation of organic substances, nitrification of ammonia nitrogen, and denitrification by reduction of nitrate nitrogen. The present invention relates to a wastewater treatment method and a microorganism carrier using a plastic microorganism carrier effective for purifying contaminated water by a reaction or the like.

[0002]

2. Description of the Related Art As one of wastewater treatment methods, there is known a fluidized bed biological treatment method in which a microorganism carrier is fluidized in a tank and assimilated microorganisms are efficiently separated from treated water together with the microorganism carrier. Microorganism carriers used in the biological treatment method include inorganic substances such as sand, coral, and ceramics, hydrogels composed of various crosslinked resins, and plastic microorganism carriers such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, and polyethylene terephthalate. It has been known.

[0003]

SUMMARY OF THE INVENTION In a fluidized-bed biological wastewater treatment method, when treating wastewater using a microorganism carrier, gravity is used as a means for separating the microorganism carrier and the treated water by a specific gravity difference. A separation method is also known, but is inefficient. A plastic microbial carrier of a pellet type with a solid content has a low use efficiency of a plastic material, and a plastic microbial carrier of a fluidized bed type having a large specific surface area is desired.

[0004]

Means for Solving the Problems In view of the above problems, the present inventors have conducted intensive studies and as a result, a hollow tubular plastic microorganism carrier having a small tube length is particularly effective as a microorganism carrier for a fluidized bed system. The present inventors have found that a microorganism carrier and treated water can be efficiently separated by a separator such as a slit, and have accomplished the present invention.

According to the first aspect of the present invention, a microbial carrier made of hollow tubular plastic having microorganisms attached thereto is brought into contact with water to be treated, and the microorganisms on the surface of the plastic microbial carrier are used to remove contaminants in the water to be treated. A wastewater treatment method comprising separating the plastic microbial carrier and treated water by a separator selected from the group consisting of a slit, a perforated plate and a net. Thus, the method for promoting wetting of a plastic carrier is characterized by suppressing the initial water repellency of the plastic microorganism carrier.

[0006] The invention of claim 2 of the present invention is to provide a method of contacting a microbial carrier made of a hollow tubular plastic having microorganisms attached thereto with water to be treated and removing BOD components in the water to be treated by microorganisms on the surface of the plastic microbial carrier. The method for treating wastewater according to claim 1, wherein the plastic microorganism carrier and the treated water are separated by a slit.

[0007] The invention of claim 3 of the present invention is used in a fluidized bed biological treatment method having a structure in which a microbial carrier made of hollow tubular plastic floats and flows in a wastewater treatment tank. The method for treating wastewater described in 1. above.

According to a fourth aspect of the present invention, there is provided the method for treating wastewater according to any one of the first to third aspects, wherein the microbial carrier made of hollow tubular plastic is used in an aerobic fluidized bed biological treatment method. It is.

The invention according to claim 5 of the present invention is characterized in that the hollow tubular plastic microbial carrier is used in an anaerobic fluidized bed biological treatment method, and the wastewater treatment method according to any one of claims 1 to 3, wherein It is.

[0010] The invention according to claim 6 of the present invention is characterized in that a hollow tubular plastic microbial carrier is used in which the relationship between the outer diameter of the hollow tubular plastic microbial carrier and the tube length is such that the outer diameter is greater than or equal to the tube length. A method for treating wastewater according to any one of claims 1 to 5.

[0011] The invention of claim 7 of the present invention is a microorganism carrier characterized in that the relationship between the outer diameter and the tube length of the hollow tubular plastic microorganism carrier is such that outer diameter ≧ tube length.

The invention according to claim 8 of the present invention is the microorganism carrier according to claim 7, wherein the relationship between the inner diameter of the hollow tubular plastic microorganism carrier and the size of the tube length satisfies the relationship of inner diameter ≧ tube length.

The invention of claim 9 of the present invention is characterized in that the material of the microbial carrier made of hollow tubular plastic is made of polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyethylene terephthalate or derivatives thereof. Item 10. A microorganism carrier according to item 8.

According to a tenth aspect of the present invention, the microbial carrier according to any one of the seventh to ninth aspects, wherein both the outer diameter and the tube length of the microbial carrier made of a hollow tubular plastic are 1 mm to 10 mm. It is.

The invention according to claim 11 of the present invention is the microorganism carrier according to claims 7 to 10, wherein the true specific gravity of the hollow tubular plastic microorganism carrier is 0.8 to 1.5. is there.

According to a twelfth aspect of the present invention, the true specific gravity of the microbial carrier made of hollow tubular plastic is 0.95 to 1.05.
The microorganism carrier according to any one of claims 7 to 11, wherein

A thirteenth aspect of the present invention is the microorganism carrier according to any one of the seventh to twelfth aspects, wherein the microbial carrier made of a hollow tubular plastic is a microbial carrier for a fluidized bed type biological treatment.

According to a fourteenth aspect of the present invention, there is provided the microorganism carrier according to any one of the seventh to thirteenth aspects, wherein the surface of the microbial carrier made of a hollow tubular plastic has irregularities.

A fifteenth aspect of the present invention is characterized in that the surface of the hollow tubular plastic microbial carrier has irregularities due to a non-plastic material selected from the group consisting of bursting bubbles, mineral powder and organic powder. The microorganism carrier according to any one of claims 7 to 14.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION A first limitation of the present invention is that a microbial carrier made of hollow tubular plastic having microorganisms attached thereto is brought into contact with water to be treated, and contaminants in the water to be treated are removed by microorganisms on the surface of the microbial carrier made of plastic. A method for treating wastewater, comprising removing the plastic microbial carrier and treated water after removal by a separator selected from any of slits, perforated plates and nets. A second limitation of the present invention is that in the method for treating wastewater according to claim 1, the microbial carrier made of hollow tubular plastic having microorganisms attached thereto is brought into contact with the water to be treated, and the BOD in the water to be treated is treated with the microorganisms on the surface of the plastic microorganism carrier. After removing the components, the plastic microbial carrier and the treated water are separated by a slit. A third limitation of the present invention is that, in the method for treating wastewater according to claim 1 or claim 2, the method is used for a fluidized bed biological treatment method in which a hollow tubular plastic microorganism carrier floats and flows in a wastewater treatment tank. And A fourth limitation of the present invention is that in the method for treating wastewater according to claims 1 to 3, the hollow tubular plastic microbial carrier is used in an aerobic fluidized bed biological treatment method. A fifth limitation of the present invention is the method for treating wastewater according to any one of claims 1 to 3, wherein the hollow tubular plastic microbial carrier is used in an anaerobic fluidized bed biological treatment method. A sixth limitation of the present invention is that, in the method for treating wastewater according to claims 1 to 5, the method relationship between the outer diameter of the hollow tubular plastic microorganism carrier and the size of the tube length is outer diameter ≧
It is characterized by using a microbial carrier made of a hollow tubular plastic having a tube length. A seventh limitation of the present invention is a microorganism carrier characterized in that the relationship between the outer diameter and the tube length of the hollow tubular plastic microorganism carrier is such that outer diameter ≧ tube length.
An eighth limitation of the present invention is the microorganism carrier according to claim 7,
The relationship between the inner diameter of the microbial carrier made of hollow tubular plastic and the size of the tube length is characterized in that the inner diameter ≧ the tube length. A ninth limitation of the present invention is that in the microorganism carrier according to claim 7 or claim 8, the material of the hollow tubular plastic microorganism carrier is made of polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyethylene terephthalate or a derivative thereof. And According to a tenth limitation of the present invention, in the microorganism carrier according to any one of claims 7 to 9, the outer diameter and the tube length of the hollow tubular plastic microorganism carrier are both 1 mm to 10 mm. An eleventh limitation of the present invention is characterized in that, in the microorganism carrier according to any one of claims 7 to 10, the true specific gravity of the hollow tubular plastic microorganism carrier is 0.8 to 1.5. A twelfth limitation of the present invention is the microorganism carrier according to any one of claims 7 to 11, wherein the true specific gravity of the hollow tubular plastic microorganism carrier is 0.95 to 1.05. A thirteenth limitation of the present invention is the microorganism carrier according to any one of claims 7 to 12, characterized in that the microorganism carrier made of hollow tubular plastic is a microorganism carrier for fluidized bed biological treatment. A fourteenth limitation of the present invention is the microorganism carrier according to any one of claims 7 to 13, wherein the surface of the hollow tubular plastic microorganism carrier has irregularities. The fifteenth limitation of the present invention is the microorganism carrier according to any one of claims 7 to 14, wherein bursting bubbles are contained in the hollow tubular plastic microorganism carrier,
The carrier is characterized by having irregularities on its surface by having a non-plastic material selected from mineral powder or organic powder.

[0021] The wastewater treatment method of the present invention is characterized in that wastewater treatment is performed using a hollow tubular plastic microbial carrier, and the treated water and the microbial carrier are separated by a separator such as a slit. It is characterized in that it is used in a fluidized bed biological treatment method having a structure that floats and flows in a treatment tank. The slit is selected because it has the strongest structure in terms of strength, compared to a perforated plate, net, etc.
The hollow tubular plastic microbial carrier has a larger apparent outer size than the solid plastic microbial carrier, so it can be easily separated by a separator such as a slit, and has excellent fluidity and microorganisms can propagate on the inner surface of the tube. Therefore, there is an advantage that the effective surface area per weight increases and the processing efficiency is excellent. When there is a relationship of outer diameter ≧ tube length between the outer diameter and tube length of the hollow tubular plastic microorganism carrier,
Not only does the water to be treated easily flow through the inner surface of the pipe, but also the pipe end hits the slit or the like to clean the slit face, remove slime or the like, and exert the effect of cleaning the slit face. If the outer diameter is smaller than the pipe length, the outer circumference of the pipe will hit the slits, etc. (because the rounded outer circumference will hit the slits instead of the pipe end with the edge), the effect of cleaning the slit surface is not so good. Can't expect. The aerobic fluidized bed biological treatment method in which oxidizing gas such as air is blown is the most common, while gas agitation is frequently used for the floating flow of the carrier, but such methods as denitrification treatment that reduces nitrogen oxides and methane fermentation are used. An anaerobic fluidized bed biological treatment method can be applied by a method of blowing anaerobic gas, and the carrier can be floated and flown by mechanical stirring using a paddle or the like in addition to gas stirring. Although the floating flow of the carrier is generally performed continuously continuously, it is also possible to perform the floating flow intermittently with a time interval. Even if the cross-sectional shape of the hollow tube is not only a circle but also an ellipse or a square shape, it does not essentially hinder the practice of the present invention.

The microbial carrier of the present invention is a microbial carrier made of a hollow tubular plastic having a relation of outer diameter ≧ tube length between outer diameter and tube length, which is used in the wastewater treatment method and the like. The aforementioned effect of cleaning the slit surface is brought about by the relationship. The microbial carrier made of hollow tubular plastic having a relationship of inner diameter ≧ pipe length between the inner diameter and the pipe length has a more excellent surface area increasing effect in which the water to be treated easily flows on the inner surface of the pipe,
Of course, since the outer diameter is larger than the pipe length, an effect of cleaning the slit surface can be expected, and the above-mentioned limitation is made more severe. The material of the microbial carrier made of hollow tubular plastic is selected from high-strength plastic materials. Specifically, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyethylene terephthalate, and the like are desirable, and waste plastic containing these may be used. . Considering the two points of separation and fluidity by a slit or the like, the size of the microbial carrier made of hollow tubular plastic is preferably 1 mm to 10 mm for both the outer diameter and the tube length. If it exceeds, the fluidity deteriorates. The true specific gravity of the microbial carrier made of hollow tubular plastic is closer to the specific gravity of water, the better the fluidity is.
If it is less than 8 or more than 1.5, the fluidity will be poor. In particular, a range with good fluidity is a true specific gravity of 0.95 to 1.05. The surface of the microbial carrier made of a hollow tubular plastic is more easily adhered and fixed by microbes as it has irregularities. As a method for forming irregularities, a rough surface is created by coexisting a non-plastic material as defined in claim 15. be able to. Ruptured air bubbles are formed by mixing air bubbles into plastic before molding and molding and injecting the air bubbles near the surface to be exploded, and the type of gas forming the air bubbles can be arbitrarily selected. Examples of the contaminants other than the burst bubbles that roughen the surface include mineral substances such as glass powder, fine sand and clay, and organic substances such as pulp, sawdust and coal powder.

(Embodiment) An embodiment of the present invention in a biological treatment apparatus used in the wastewater treatment method according to the present invention will be described below in detail with reference to the drawings. 1 is a sectional view showing an embodiment of a biological treatment apparatus for wastewater according to the present invention, FIG. 2 is a plan view of the biological treatment apparatus for wastewater shown in FIG. 1, and FIG. 3 is a separator such as a slit attached to the biological treatment apparatus shown in FIG. FIG. 4 is a cross-sectional view showing one embodiment of the slit.

This wastewater biological treatment apparatus has an aeration tank 1 made of a material such as FRP, steel, stainless steel, concrete and the like. The aeration tank 1 forms an aeration chamber 2, and a wastewater inlet 3 for supplying wastewater 14 into the aeration chamber 2.
And an outlet 5 for discharging the treated water 15 from the aeration chamber 2. The wastewater 14 is purified together with the microorganism carrier (made of hollow tubular plastic) 13 into the treated water 15 in the aeration chamber 2. In the aeration chamber 2, an aeration pipe 4 as a diffuser through which gas is sent from a gas supply blower 12 through a gas pipe 11 and a gas tube 6 is provided to flow the wastewater 14 and the microorganism carrier 13 in the aeration chamber 2. I have. The air diffuser 4 is attached to the tip of the gas tube 6, and can be installed at an optimum position by hanging the gas tube 6 into the aeration chamber 2. An outflow trough 8 is provided adjacent to the aeration chamber 2. The outflow trough 8 is provided with an overflow partition 9 and a drain pipe 10. The outflow trough 8 receives the treated water 15 that has passed through the outlet 5, and the treated water 1 that has overflowed the overflow partition 9.
5 is discharged through a drain pipe 10.

The wastewater biological treatment apparatus is characterized in that a slit (representative of a separator) 7 for separating the microorganism carrier 13 and the treated water 15 is provided at the outlet 5. The slit 7 has a function of separating the microorganism carrier 13 and the treated water 15, keeping the microorganism carrier 13 in the aeration chamber 2, and discharging the treated water 15 from the outlet 5.
Further, the outflow trough 8 is composed of the treated water 15 passing through the slit 7.
And the treated water 15 flowing out of the overflow bulkhead 9 is drained into the drain pipe 1.
Discharge through 0. In the aeration chamber 2, the wastewater 14 and the microorganism carrier 13 flow through the aeration chamber 2 in a state where the wastewater 14 and the microorganism carrier 13 collide with the slit 7 in the area of the slit 7 of the outlet 5 due to the flow action of water bubbles injected from the diffusion pipe 4. I do. Diffuser 4
The gas diffused into the aeration chamber 2 from the air is air, N ₂ gas,
It is methane gas or the like, and is selected depending on the type of wastewater treatment such as aerobic treatment, anaerobic denitrification treatment, and anaerobic digestion treatment.

In the wastewater biological treatment apparatus, the slit 7
Is detachably attached to the edge of the outlet 5 by fixing means 21 such as screws and bolts. The slit 7
In particular, in order to enhance the separation effect between the microorganism carrier 13 and the treated water 15, they are sequentially arranged in parallel in the direction perpendicular to the liquid level in the aeration chamber 2. The slit 7 as shown in FIG. 4, so that the aeration tank 1 inner or aeration chamber 2 side is formed in the edge 18 of the acute angle theta _E, cross-sectional area increases from the aeration chamber 2 side to the outside of the outlet trough 8 side Lattice with trapezoidal cross section 1
7 is formed. The biological treatment device described here may be used alone, or a plurality of treatment units may be arranged in series to increase the treatment efficiency. It may just be provided.

The results of aerobic biological treatment of the BOD cut before discharge into the sewer using the wastewater treatment equipment of the paper company using this wastewater biological treatment apparatus are shown below. Two types of polypropylene hollow tubular microbial carriers whose surfaces were roughened by bursting bubbles were used as the microbial carriers as the microbial carriers, with the slit 7 having a slit gap of 2 mm as a separator. The microorganism carrier 1 has a cylindrical shape with an outer diameter of 4 mm, an inner diameter of 3 mm, and a tube length of 3 mm. Microbial carrier 2 has an outer diameter of 4 mm, an inner diameter of 3 mm, and a tube length of 5
mm. The true specific gravity of both was 0.97. As a comparative example, a test was conducted by combining a column-shaped microorganism carrier 3 having a true specific gravity of 0.99 made of polypropylene containing closed cells and glass powder and having an outer diameter of 4 mm and a tube length of 5 mm. Evaluation is based on the agglomerated water (around 100 ppm BOD)
The BOD volume load that can maintain the BOD cut ratio of 60% was determined for each carrier 1 month and 3 months after the start of the test. The apparent volume ratio of the added amount of the carrier to the aeration tank is 15%. The BOD volume load after one month was 4 kg / m ^{3 for} the microorganism carrier 1 and 3 kg for the microorganism carrier 2.
It was 2 kg / m ^{3 for} the microorganism carrier 3 and 2 kg / m ³ .
One month later, no slime was attached to the slit 7. The BOD volume load after 3 months was 4 kg / m ³ for microorganism carrier 1 and 2.5 kg / m ³ for microorganism carrier 2.
^{3. The} microbial carrier 3 had a weight of 2 kg / m ³ . Three months later, no slime was adhered to the slit 7 in the microbial carrier 1 but the microbial carrier 2 and the microbial carrier 3
In the apparatus described above, slime adhered to the slit 7 and periodic cleaning was required.

[0028]

According to the present invention, the hollow tubular microbial carrier is clearly separated by the slit, and no damage is observed even during long-term use. Particularly, in the case of the microbial carrier 1 having an outer diameter ≧ tube length, a high purification ability is maintained even after 3 months and the slit is maintained. It was also effective in preventing slime from adhering. Hollow tubular microbial carriers are economical because of their low material costs, and their large specific surface area makes it easier to ensure fluidity than pellets even when the true specific gravity is farther from water. have. The hollow tubular microbial carrier according to the present invention has a great economic effect because it efficiently maintains a wastewater treatment method using the same and is inexpensive.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a biological treatment apparatus for wastewater according to the present invention.

FIG. 2 is a top view of the biological treatment apparatus for wastewater shown in FIG. 1;

FIG. 3 is a sectional view showing a slit incorporated in the wastewater biological treatment apparatus of FIG. 1;

FIG. 4 is a cross-sectional view showing one embodiment of a slit in the wastewater biological treatment apparatus of FIG.

[Explanation of symbols]

 1. Aeration tank 2. Aeration chamber 3. Wastewater supply port 4. Air diffuser 5. Outlet 6. Gas tube 7. Slit 8. Spill trough 9. Overflow bulkhead 10. Drain pipe 11. Gas pipe 12. Gas supply blower 13. Microbial carrier 14. Wastewater 15. Treated water 17. Lattice 18. Edge

Claims (15)

[Claims] 1. A microbial carrier made of hollow tubular plastic having microorganisms attached thereto is brought into contact with water to be treated, and microorganisms on the surface of the microbial carrier made of plastic remove contaminants in the water to be treated. A method for treating wastewater, wherein water is separated by a separator selected from a slit, a perforated plate and a net. 2. A microbial carrier made of hollow tubular plastic to which microorganisms have adhered is brought into contact with water to be treated, and microorganisms on the surface of the microbial carrier made of plastic remove contaminant components in the water to be treated. The method for treating wastewater according to claim 1, wherein the treated water is separated by a slit. 3. The method for treating wastewater according to claim 1, wherein the microorganism support made of hollow tubular plastic is used in a fluidized bed biological treatment method having a structure in which the microorganism carrier floats and flows in a wastewater treatment tank. 4. The method for treating wastewater according to claim 1, wherein the microbial carrier made of hollow tubular plastic is used in an aerobic fluidized bed biological treatment method. 5. The method for treating wastewater according to claim 1, wherein the microbial carrier made of hollow tubular plastic is used for an anaerobic fluidized bed biological treatment method. 6. The microbial carrier made of hollow tubular plastic according to claim 1, wherein the relationship between the outer diameter of the microbial carrier made of hollow tubular plastic and the size of the tube length is such that outer diameter ≧ tube length. Wastewater treatment method. 7. A microbial carrier characterized in that the relationship between the outer diameter and the tube length of the hollow tubular plastic microbial carrier is such that outer diameter ≧ tube length. 8. The microorganism carrier according to claim 7, wherein the relationship between the inner diameter of the hollow tubular plastic microorganism carrier and the size of the tube length is: inner diameter ≧ tube length. 9. The microbial carrier according to claim 7, wherein the material of the microbial carrier made of hollow tubular plastic is made of polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyethylene terephthalate or a derivative thereof. 10. The microorganism carrier according to claim 7, wherein both the outer diameter and the tube length of the microbial carrier made of hollow tubular plastic are 1 mm to 10 mm. 11. The microorganism carrier according to claim 7, wherein the true specific gravity of the microorganism carrier made of a hollow tubular plastic is 0.8 to 1.5. 12. The microorganism carrier according to claim 7, wherein the true specific gravity of the microorganism carrier made of hollow tubular plastic is 0.95 to 1.05. 13. The microbial carrier according to claim 7, wherein the microbial carrier made of a hollow tubular plastic is a microbial carrier for a fluidized bed type biological treatment. 14. The microorganism carrier according to claim 7, wherein the surface of the microorganism carrier made of a hollow tubular plastic has irregularities. 15. The surface of the hollow tubular plastic microbial carrier having irregularities due to the presence of a non-plastic material selected from the group consisting of bursting bubbles, mineral powder, and organic powder. 14
A microorganism carrier according to item 1.