JP2004223320A - Aeration treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aeration treatment device having the characteristics of both of an activated sludge system and a biological membrane system. <P>SOLUTION: A cylindrical body 3 is vertically provided in an aeration tank 1. Upper and lower perforated plates 5 and 6 are provided in the cylindrical body 3 and the space between the perforated plates 5 and 6 is filled with a large number of ceramic granular biological membrane carriers 7. A sewage inflow port 8 is provided to the lower end of the cylindrical body 3, and an air diffuser 10 for supplying air into the aeration tank 1 and an air diffuser for supplying air into the cylindrical body 3 are respectively arranged on the bottom part of the aeration tank 1. The biological membrane carriers 7 are fluidized in the cylindrical body by the pressure of air sent from the air diffusers. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an aeration treatment apparatus for purifying domestic wastewater and industrial wastewater such as human wastewater, livestock manure wastewater, and industrial wastewater by aeration treatment.
[0002]
[Prior art]
Activated sludge treatment methods conventionally known as purification methods for wastewater containing organic matter such as domestic sewage and animal manure are described in detail in, for example, the following literature.
[0003]
[Non-patent document 1]
"Maintenance of septic tanks" supervised by the Water Environment Department, Ministry of Health and Welfare, Ministry of Health and Welfare, April 1985, edited and published by Japan Environmental Improvement Education Center, 30-31,171,198
[0004]
In other words, the activated sludge treatment method is a method in which microorganisms contained in the wastewater are proliferated and activated while supplying air to the wastewater stored in the aeration tank, and the microorganisms are decomposed and eaten by organic substances, which are pollutants. is there. The treated water is transferred to a sedimentation tank and separated into a supernatant liquid and settled sludge.A part of the settled sludge is returned to the same tank to stabilize the activated sludge in the aeration tank, and excess sludge is collected. Sludge is transferred to a separate tank and transported to sewerage treatment facilities. Further, the supernatant is subjected to necessary sterilization treatment and then discharged to a river or discharged to a sewer as it is.
[0005]
The above-mentioned aeration tank is a tank that plays the most important role in the activated sludge treatment method. There is a contact aeration system for processing. 3 to 5 show examples of aeration tanks designed and constructed in the past.
[0006]
FIG. 3 shows an example of the activated sludge method, in which a predetermined amount of air is supplied from an air diffuser 31 into an aeration tank 30, and a sewage purification treatment is performed by floating microorganisms while slowly stirring the sewage. FIG. 4 shows an example of a contact aeration system, in which a contact material 32 having a multi-layered mesh structure is mounted inside an aeration tank 30, a microbial membrane is attached to the contact material 32 and generated, and wastewater is contaminated using the microbial membrane. It preys on organic matter inside. FIG. 5 shows an example of the biofilm system, in which a number of granular biofilms made of plastic, sponge, etc. are provided between mesh-like support plates 34, 34 mounted on the upper and lower sides of the aeration tank 30. The carrier 35 is loaded.
[0007]
[Problems to be solved by the invention]
In the activated sludge method shown in FIG. 3, a part of the settled sludge is returned from the settling tank to the aeration tank 30 as described above. It is difficult to stabilize the sludge concentration in the inside, and when operating at a high sludge concentration, the purification capacity is increased, but the treatment capacity is limited, especially in a small aeration tank, and the sludge flows out to the sedimentation tank, As a result, there is a problem that excess sludge increases. In addition, seed sludge needs to be introduced at the time of start-up, and since this sludge may flow out to the sedimentation tank before multiplying in the aeration tank 30, a certain MLSS (active sludge floating substance) is held. There is a problem that it takes time until.
[0008]
In addition, the contact aeration method shown in FIG. 4 has a smaller flow rate of microorganisms with respect to fluctuations in the amount of wastewater, has a stable purification capacity, has less excess sludge, and returns sludge from the sedimentation tank, compared to the activated sludge method. There is an advantage such that the trouble of doing it can be omitted. However, since the supply of nutrients and oxygen is limited to the surface of the biofilm, it is necessary to uniformly supply oxygen to the entire surface of the contact material 32 by the air diffuser 31, and the contact material 32 is a biofilm. In order to prevent thickening, there is a problem that it is necessary to sometimes remove the biofilm of the contact material 32 by the backwashing device 33 and discharge the biofilm from the tank. In addition, the contact material 32 needs to be supported and fixed to the gantry 36 provided at a plurality of locations inside the aeration tank 30. Since these are assembled individually at the construction site, productivity is low and construction cost is low. There is a problem such as becoming high.
[0009]
Further, in the biofilm system shown in FIG. 5, a large amount of the biofilm carrier 35 of about 50 to 60% of the capacity of the aeration tank has to be loaded, and the mesh supporting plate 34 depends on the weight of the biofilm carrier 35. Is weak, for example, the connection part (the part in the figure) with the aeration tank 30 may be damaged and the biofilm carrier 35 may jump out or fall off. Since the entire surface needs to be aerated by the air diffuser 31 from below, there is a problem that the air diffuser 31 is difficult to replace.
[0010]
The present invention has been proposed to solve the above problems. That is, the present invention makes use of the characteristics of both the activated sludge method and the biofilm method in the same aeration tank, and can perform a stable purification treatment even if there is a concentration fluctuation of the inflowing wastewater, and can remove excess sludge. An object of the present invention is to provide an aeration apparatus capable of reducing the generation.
[0011]
In addition, the present invention enables uniform supply of air to the entire biofilm carrier, improves and stabilizes the purification ability of the biofilm carrier, and enables the operation to be started up in a short time after installation. It is still another object of the present invention to provide an aeration apparatus capable of naturally removing sludge adhering to a biofilm carrier without using a special apparatus.
[0012]
In addition, the present invention can be easily assembled in a factory line, can be mass-produced at low cost, can shorten the construction period at the construction site, and can be easily repaired and maintained at low cost. An object of the present invention is to provide a practicable aeration apparatus.
[0013]
[Means for Solving the Problems]
In order to solve the above-described problems, an aeration processing apparatus according to the present invention includes a cylinder which is provided to stand substantially at a central portion of the aeration tank, and an air supply which sends air into the interior of the aeration tank and the interior of the cylinder, respectively. And means,
The cylindrical body is provided with perforated plates at the top and bottom inside thereof, and between these perforated plates, a number of biofilm carriers flowing by the air pressure of the air supply means are loaded, and the lower perforated plate of the cylindrical body is provided. A sewage inlet for guiding sewage in the aeration tank into the cylinder is provided at a position lower than
The means for sending air into the inside of the cylindrical body discharges air from below the lower porous plate toward the biofilm carrier.
[0014]
Thereby, the sewage in the aeration tank circulates through the inside of the cylinder and is aerated by the air (oxygen) supplied by each air supply means, and at the same time, the sewage contacts the biofilm carrier inside the cylinder. Then, purification by a biofilm method is performed. In addition, the biofilm carrier flows in the vertical direction inside the cylinder by air pressure, during which the biofilm carriers collide with each other, and the excess sludge attached to the biofilm carrier is separated, and the circulating flow of the wastewater Is released to the outside of the cylinder and is generated as activated sludge outside the cylinder.
[0015]
The structure of the aeration tank is arbitrarily designed depending on conditions such as a sewage treatment amount, an installation place, and the like. The diameter and length of the cylindrical body are also designed according to the structure of the aeration tank and the sewage treatment conditions. If necessary, a plurality of cylinders may be provided in the aeration tank.
[0016]
The perforated plate holds the biofilm carrier loaded inside the cylinder, and is fixed to the cylinder by means such as welding or fixing bolts. As the perforated plate, a plate having a large number of pores formed in a flat plate, a mesh material having a predetermined mesh hole, or the like can be selected. Is used.
[0017]
The biofilm carrier is made of various materials such as plastic, sponge, charcoal and the like. Here, a ceramic carrier which is excellent in BOD removal performance and durability, and has high strength and relatively light weight is used. The ceramic carrier is loaded in an amount of about 70 to 80% between the upper and lower perforated plates. The ceramic carrier is obtained by granulating a ceramic raw material produced as a by-product in a foundry or a cement plant by a firing method or the like, and has countless holes. The ceramic carrier has a particle size that does not pass through the holes of the perforated plate, and has a weight that is large enough to flow through the cylinder by the air pressure of the air supply means.
[0018]
The air supply means is not particularly limited, but a diffuser is used here. From the air diffuser, an amount of air that causes a predetermined DO (dissolved oxygen amount) in the aeration tank is sent. It is preferable to send air at a DO of 1 mg / L or more to such an extent that the biofilm portion does not become anaerobic.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. In FIG. 1, reference numeral 1 denotes a tank-type aeration tank, which is installed underground while being supported by a base 2. Although not shown, the aeration tank 1 is connected to an inflow pipe for introducing sewage from an inflow tank and a discharge pipe for discharging a processing solution to a settling tank. A cylindrical body 3 as shown in FIG. 2 is erected at a substantially central portion inside the aeration tank 1, and the cylindrical body 3 is fixed to the bottom of the aeration tank 1 by fixing means such as fixing bolts. I have.
[0020]
Perforated plates 5 and 6 are fixed above and below the cylindrical body 3, and a large number of ceramic biofilm carriers 7 are loaded between the porous plates 5 and 6 at about 70 to 80% of the volume of the cylindrical body. Have been. The perforated plates 5 and 6 are made of a disc-shaped SUS punched metal, and have a large number of holes of about 3 mm. The biofilm carrier 7 has numerous holes. Further, at the lower end of the cylindrical body 3, a plurality of sewage inflow ports 8 are opened at positions below the lower porous plate 5. The cylindrical body 3 loaded with the biofilm carrier 7 is assembled inside the aeration tank 1 on an assembly line.
[0021]
On the other hand, at the bottom of the aeration tank 1, a diffuser 9 (see FIG. 2) for supplying air to the inside of the cylindrical body 3 and a diffuser 10 (for supplying air to the inside of the aeration tank 1). 1 (see FIG. 1). The air diffuser 9 has a configuration in which an air diffusion nozzle portion is inserted at a position below the lower porous plate 5 of the cylindrical body 3 and can be easily removed from the cylindrical body 3.
[0022]
Next, an operation example of the above-described aeration apparatus will be described. First, the aeration tank 1 is filled with the sewage flowing from the inflow tank. However, at the time of startup, the sewage flowing into the cylinder 3 from the sewage inlet 8 of the cylinder 3 adheres to the biofilm carrier 7. Until the MLSS in the aeration tank 1 is maintained at a predetermined amount, the purification process is performed by the microorganisms generated in the cylindrical body 3.
[0023]
The sewage in the aeration tank 1 is subjected to aeration while being circulated in the tank in the direction indicated by the arrow in FIG. 1 by the pressure of air sent from the aeration devices 9 and 10, thereby purifying the sewage by microorganisms. That is, the sewage in the cylinder 3 flows into the interior of the cylinder 3 from the sewage inlet 8, passes through the lower porous plate 5 by the ascending flow generated by the air diffuser 9, and passes through the ceramic biofilm carrier 7. While flowing uniformly out of the cylinder 3.
[0024]
A microbial membrane is formed and fixed on the biofilm carrier 7, and when the sewage contacts a large number of biofilm carriers 7, the organic substance that is a pollutant is decomposed. In this case, the air sent from the air diffuser 9 collides with the lower perforated plate 5, disperses, rises through the holes of the perforated plate 5 while dissolving in water, and adheres to the microorganism carrier 7. Contact with microorganisms. Dissolved oxygen is finer due to bubbles in the sewage colliding with the biofilm carrier 7, so that a higher concentration of dissolved oxygen is generated as compared with a normal activated sludge treatment method. Further, the sewage flowing into the cylinder 3 contains dissolved oxygen by the diffuser 10 outside the cylinder, the microorganisms attached to the biofilm carrier 7 are activated, and the decomposition and predation of organic substances are promoted.
[0025]
Sludge gradually adheres to the surface of the biofilm carrier 7. However, since the biofilm carriers 7 constantly collide with each other while flowing vertically, the attached sludge naturally spreads after a predetermined period of time. It separates from the body 7 and is discharged outside the cylinder, and is generated as sludge outside the cylinder. Since the flowing biofilm carrier 7 also collides with the upper and lower perforated plates 5 and 6, the sludge attached to the perforated plates 5 and 6 is also separated.
[0026]
On the other hand, on the outside of the cylindrical body 3, the sewage is aerated by the diffuser 10, and normal activated sludge treatment is performed. In general, the microorganisms that appear in the activated sludge treatment method are floc-forming bacteria and micro-animals (protozoa) that have stuck to or crawled on the flocs. The bacteria are responsible for the decomposition of organic matter in the wastewater, and the micro-animals prey on the bacteria. It is said that this has the effect of reducing the generated sludge and making the treated water transparent. In the ordinary activated sludge treatment method, the environment is disadvantageous for the survival of micro-animals because it is constantly agitated by aeration, and organisms having a low growth rate are washed away by the ungrown fish in the aeration tank 1. I will. However, in the present invention, micro-animals that are disadvantageous as an activated sludge treatment method, microorganisms that have a low growth rate, and micro-metamorphous animals that are extremely sensitive to the agitation speed of aeration are formed on the biofilm carrier 7 of the cylinder 3. Thus, diversification of organisms involved in sludge treatment can be achieved in combination with microorganisms living in the aeration tank 1. Therefore, it is possible to cope with various inflow sewage environments, and a stable sewage purification process can be performed.
[0027]
In addition, in the ordinary activated sludge treatment method, the specific growth rate of organisms decreases with a decrease in water temperature, but in the present invention, the diversity of organisms increases as described above, and a stable ecosystem is formed. The sewage will be purified by organisms that are resistant to low temperatures.
[0028]
The treated water that has been aerated in the aeration tank 1 is transferred to a sedimentation tank, where the sludge contained in the treated water is settled and separated, and the supernatant water is sterilized before being discharged to the river, Released into the sewer as it is.
[0029]
【The invention's effect】
According to the present invention described above, the activated sludge type and the biofilm type purification treatment methods coexist in the same aeration tank. Wastewater can be purified, and the generation of excess sludge can be reduced. In addition, since the step of returning sludge from the sedimentation tank can be omitted, equipment costs and operation costs can be suppressed, and further, the size of the entire equipment can be reduced.
[0030]
Further, according to the present invention, since air is supplied from below the cylinder through the lower perforated plate, air can be uniformly supplied to the entire biofilm carrier in the cylinder, thereby improving the purification ability of the biofilm carrier. Stabilization can be achieved. In addition, seed sludge input required at the time of conventional startup is not required, and operation can be started up in a short period of time after installation work (purification of sewage can be expected in about 2 weeks after installation of equipment). Sludge adhering to the membrane carrier collides with each other when the biofilm carrier flows through the inside of the cylindrical body, and is spontaneously separated. Therefore, a device for removing the attached sludge and a removing operation are not required.
[0031]
In addition, the present invention, in which the biofilm carrier is loaded between the perforated plates fixed in the cylinder, requires less loading of the biofilm carrier than the conventional biofilm method, and the weight is light, so the perforated plate is light. Damage, falling off of the biofilm carrier and the like can be prevented.
[0032]
Further, according to the present invention, mass production can be realized at low cost because assembly can be easily performed in a factory line, and assembly work at a construction site can be omitted, so that the construction period can be shortened. Further, repair and maintenance such as replacement of the diffuser can be easily performed, and the maintenance cost is inexpensive.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an embodiment of an aeration apparatus of the present invention.
FIG. 2 is a schematic diagram showing an internal configuration of a cylindrical body in FIG.
FIG. 3 is a schematic view of a conventional activated sludge type aeration tank.
FIG. 4 is a schematic view of a conventional contact aeration type aeration tank.
FIG. 5 is a schematic view of a conventional biofilm type aeration tank.
[Explanation of symbols]
1 is an aeration tank 2, a base 3 is a cylinder 5, 6 is a perforated plate 7, a biofilm carrier 8 is a sewage inlet 9, 10 is an aeration device

Claims (2)

In an aeration treatment device that sends air to sewage in an aeration tank and purifies sewage by microorganisms,
A cylinder provided upright at a substantially central portion of the aeration tank, and air supply means for sending air to the inside of the aeration tank and the interior of the cylinder, respectively.
The cylindrical body is provided with perforated plates at the top and bottom inside thereof, and between these perforated plates, a number of biofilm carriers flowing by the air pressure of the air supply means are loaded, and the lower perforated plate of the cylindrical body is provided. A sewage inlet for guiding sewage in the aeration tank into the cylinder is provided at a position lower than
The aeration apparatus, wherein the means for supplying air into the cylindrical body discharges air from below the lower porous plate toward the biofilm carrier. The aeration processing apparatus according to claim 1, wherein the biofilm carrier is a granular porous ceramic material.

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