JP3894606B2 - Aeration apparatus for sewage aerobic treatment tank and aerobic treatment tank of sewage equipped with the aeration apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an aeration apparatus for sewage aerobic treatment tank and an aerobic treatment tank of sewage equipped with the aeration apparatus, in particular organic wastewater such as sewage, human waste, industrial wastewater, etc. using a microorganism-immobilized carrier, The present invention relates to an aerobic treatment tank for biological treatment and an aeration apparatus installed in the aerobic treatment tank.
[0002]
[Prior art]
In recent years, the activated sludge method, biofilm method, immobilized microbiological method, etc. have been widely used, but in Japan where the efficiency of land use is called out, it is urgent to develop a high-performance sewage treatment device capable of processing in a smaller area. It is.
Among these, sewage treatment apparatuses that use a microorganism-immobilized carrier have been attracting attention in conjunction with improved performance of the carrier material.
[0003]
The present applicant has developed a sewage treatment apparatus using the immobilization carrier shown in FIG. In FIG. 9, reference numeral 1 denotes an aerobic treatment tank (hereinafter referred to as an aerobic tank), and a large number of carriers 2 in which microorganisms held in a floating state are immobilized are accommodated in the aerobic tank 1. At the bottom of the aerobic tank 1, a fine bubble diffuser 53 comprising a diffuser and a diffuser tube is disposed. The air diffuser 53 is connected to the blower 4 via the air supply pipe 5. The liquid to be processed flows into the aerobic tank 1 from the inflow pipe 7, and the aerobic processed liquid flows out from the processing liquid outflow pipe 8. A carrier separator 6 for separating the carrier 2 from the processing liquid is disposed at the inlet of the outflow pipe 8.
[0004]
The present applicant has encountered the following technical problems during the development process for a sewage treatment apparatus using the immobilization carrier shown in FIG.
That is, as a result of the immobilized carrier flowing down the biological reaction tank together with the liquid to be treated, the carrier concentration at the tip of the reaction tank decreases and the carrier concentration at the end increases, and the entire bottom of the aerobic reaction tank. The carrier accumulated in the gap between the diffuser and the bottom of the concrete, and the carrier injection rate significantly higher than the planned amount of carrier needed. In addition, the processing performance was significantly reduced due to the deviation of the carrier.
[0005]
For this reason, it has been studied to arrange a carrier flow prevention wall or to provide a separate agitation transfer means, but there are problems in terms of processing capacity, equipment costs, and operating costs.
These are because of concern about the destruction of the carrier, and the oxygen dissolution rate is high as an aeration means, but the treatment was performed using a diffuser or a full aeration tank with an aeration tube with little stirring power.
By the way, at present, various microorganism-immobilized carriers having sufficient strength against stirring have been developed.
[0006]
[Problems to be solved by the invention]
The present invention has been made in view of the above-described circumstances, and an aerobic treatment tank aeration apparatus and an aeration apparatus capable of preventing a decrease in processing performance associated with arrangement of an apparatus that does not exhibit uneven carrier concentration distribution and a carrier function. An object of the present invention is to provide an aerobic treatment tank for sewage provided with
The present invention also provides an aerobic treatment tank aeration apparatus capable of suppressing damage, destruction and consumption of the carrier when the carrier passes through the aeration apparatus, and a sewage aerobic treatment tank equipped with the aeration apparatus. Is an issue.
[0007]
[Means for Solving the Problems]
In order to solve the above-described problem, one aspect of the present invention is an aeration apparatus installed in an aerobic treatment tank of sewage having a carrier on which microorganisms held in a floating state are immobilized, wherein the aeration apparatus includes: A casing and an axial flow impeller provided in a flow path of the liquid to be processed formed in the casing , and the liquid to be processed in the aerobic processing tank is caused by the rotation of the axial flow impeller. flows from the casing, flows through the flow path in the axial flow impeller is discharged from the casing into the aerobic treatment tank consists water aerator agitating the aerobic treatment tank, and the wing portion of the axial flow impeller The clearance between the wings and the casing is set to be larger than the maximum diameter or the maximum dimension of the carrier.
[0008]
In another aspect of the present invention, in the aerobic treatment tank of sewage having a carrier on which microorganisms held in a floating state are immobilized, one or more aeration devices are arranged at a position where the inside of the tank can be aerated and mixed uniformly. The aeration apparatus includes a casing and an axial impeller provided in a flow path of the liquid to be processed formed in the casing, and the aerobic treatment tank is rotated by the rotation of the axial impeller . treated liquid flows from the casing, flows through the flow path in the axial flow impeller is discharged from the casing into the aerobic treatment tank consists water aerator agitating the aerobic treatment tank, the axial The clearance between the blade portion of the impeller and the casing facing the blade portion is set larger than the maximum diameter or the maximum dimension of the carrier.
[0009]
The aerobic treatment tank of the present invention can be used as an aerobic treatment tank in a treatment apparatus for treating sewage by circulating nitrification denitrification or denitrification / dephosphorization.
In order to solve the problem of the conventional method in which the carrier accumulates at the end of the aerobic treatment tank due to the flow in the tank, the present invention is based on the entire aeration method using fine bubbles by a diffuser or a diffuser tube that has been used conventionally. The aeration apparatus which consists of an underwater aerator excellent in the capability to form a stirring flow is deployed instead of such a simple aeration apparatus.
[0010]
According to the present invention, since the aeration apparatus having an excellent stirring function is used, the inside of the aerobic tank is uniformly stirred without introducing an extra carrier that does not perform the function while being deposited at the bottom of the aerobic tank. Also, the offset of the carrier can be greatly improved.
Further, according to the present invention, by using an aeration apparatus in an aerobic tank, there is no decrease in oxygen dissolution efficiency due to secular change compared to a conventional full-aeration method with fine bubbles, and thus high processing performance is obtained in an aerobic tank. be able to.
[0011]
In the aeration apparatus of the present invention, the clearance between the blade portion of the impeller and the casing facing the blade portion is set larger than the maximum diameter or maximum dimension of the carrier. Therefore, the carrier is not bitten between the blade portion of the impeller and the casing, and the carrier itself can be prevented from being damaged or consumed. The maximum diameter of the carrier means the maximum outer diameter when the carrier is a sphere or an ellipsoid. The maximum dimension of the carrier means the maximum dimension when the two opposite points are the longest when the carrier is a rectangular parallelepiped, a cube, or a pyramid.
[0012]
Further, in the aeration apparatus of the present invention, the blade portion of the impeller is covered with a coating material or the surface of the blade portion is formed smoothly, so that when the carrier passes through the impeller, the blade portion of the impeller Even if contact is made, the impact at the time of contact can be alleviated, microorganisms such as nitrifying bacteria on the surface of the carrier can be prevented from peeling off, and damage and consumption of the carrier itself can be prevented.
[0013]
The immobilization carrier used in the present invention is preferably a fluid carrier such as sand, activated carbon, polyurethane foam, polyvinyl alcohol, polypropylene, polyethylene, polyethylene glycol, and cellulose, but is not necessarily limited to these carriers. Absent. As a means for immobilizing microorganisms on a carrier, an adhesion immobilization method is generally used, but a comprehensive immobilization method is also applicable. The shape of the carrier includes various shapes such as a sphere, an ellipsoid, a cuboid, a cube, and a pyramid.
Furthermore, a carrier outflow prevention means made of a porous member such as a net, a grating, or a punching plate for preventing the carrier from flowing out may be provided at the outflow end of the aerobic tank.
[0014]
In addition, the aerobic treatment tank of the present invention, for example, sequentially connects an anaerobic process, an aerobic process, and a precipitation process, circulates the aerobic process effluent water to the anoxic process, A denitrification / dephosphorization activated sludge method and apparatus for returning to the anaerobic process by providing an anaerobic process before the anaerobic process and returning the sludge from the precipitation process to the anaerobic process. Can be suitably used in an aerobic process and an aerobic treatment tank.
[0015]
As for the installation of the aeration apparatus, the number and arrangement can be appropriately selected so that uniform aeration can be performed depending on the shape of the tank.
In addition, due to the influence of the inflowing water, the carrier may be shifted to the outflow end for a very long time, and the processing performance may not be stabilized. In such a case, the liquid mixture containing the carrier is returned to the inflow part. The processing performance can also be stabilized.
When the above method is used for anaerobic / aerobic treatment, an apparatus can be installed so that the mixed liquid containing the carrier returns to the aerobic tank and the mixed liquid returns to the anaerobic tank at the return destination. The pumping capacity increases when returned in such a manner.
As a transfer pump installed at the end of the aerobic tank, it is desirable to use a pump having a special specification such as a single screw pump and an air wrist pump. In this case, it is desirable that the amount of water transferred can be arbitrarily changed by changing the number of rotations of the motor by frequency control.
[0016]
In addition, a means capable of transferring without destroying the carrier and the biofilm other than the pump may be used as appropriate. Further, a carrier separation means such as a liquid cyclone or a trommel sieve may be provided in the middle of the carrier transfer pipe, and the carrier may be distributed to the aerobic tank in each processing apparatus provided with the transfer water in the previous stage.
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of an aeration apparatus for an aerobic treatment tank of sewage according to the present invention and an aerobic treatment tank of sewage provided with the aeration apparatus will be described with reference to FIGS.
[0017]
FIG. 1 is a sectional view showing an example of an aerobic treatment tank (hereinafter referred to as an aerobic tank) according to the present invention, and FIG. 2 is a plan view. 1 and 2, reference numeral 1 denotes an aerobic tank, and a large number of carriers 2 on which microorganisms such as nitrifying bacteria held in a floating state are immobilized are accommodated in the aerobic tank 1. At the bottom of the aerobic tank 1, an aeration apparatus 10 comprising two underwater aerators is provided. The aeration apparatus 10 is connected to the blower 4 via the air supply pipe 5. An air flow meter 9 is installed in the air supply pipe 5.
[0018]
The liquid to be treated (sewage ) flows into the aerobic tank 1 from the inflow pipe 7, and the treated liquid subjected to the aerobic treatment flows out from the processing liquid outflow pipe 8. A carrier separator 6 for separating the carrier 2 from the processing liquid is disposed at the inlet of the outflow pipe 8. With the stream of liquid to be treated, because though gradually the carrier 2 moves to the outflow end, the distal end of the aerobic tank 1, the carrier in the piping 11 Ru by transferring the carrier and the circulating nitrified liquid flow A pump 3 is installed. Incidentally, it established a carrier transfer pump 3, in Rukoto to transfer the carrier 2, it becomes possible fine adjustment of carrier concentration.
[0019]
1 and 2, without placing the partition plate baffle such as aerobic tank 1, 1 as possible the vertical and horizontal lengths of the planar dimensions of the aerobic tank: the broken line 40 so as to be 1 An aeration apparatus 10 composed of one underwater aerator is arranged in each of the first half and the second half.
In the aerobic tank 1, a circulating flow as shown in FIG. 1 is formed. Immobilizing carrier 2, such a circulation flow, even without a partition plate, the degree Oh Ru, uniformly distributed over entire tank.
[0020]
Next, an example of the aeration apparatus 10 will be described with reference to FIGS.
FIG. 3 is a sectional view of the aeration apparatus of the present invention, and FIG. 4 is a plan view of the aeration apparatus of the present invention. The aeration apparatus of this example is a downward blowing type aeration apparatus.
As shown in FIGS. 3 and 4, the aeration apparatus 10 includes a casing 14 including a suction casing 12 and a discharge casing 13 that form a flow path of a liquid to be processed, a motor 15 supported by the casing 14, and air A chamber casing 16 and an impeller 17 provided in a flow path of the liquid to be processed formed in the casing 14 are provided. An air chamber 19 is formed in the air chamber casing 16, and air or oxygen is supplied to the air chamber 19 through an air supply pipe 5 connected to the blower 4 (see FIG. 1). Yes.
[0021]
In the above configuration, when the motor 15 is driven, the processing liquid in the tank containing the carrier 2 flows from the upper suction casing 12 by the rotation of the impeller 17 and flows downward in the flow path in the impeller 17. From the discharge port 13a of the discharge casing 13. On the other hand, the air supplied to the air chamber 19 through the air supply pipe 5 is jetted into the liquid to be processed in the flow path in the casing 14 from the lowermost injection port 23 through the downward flow path 22, and the liquid to be processed. The mixture is stirred and fed into the aerobic tank 1 from the discharge port 13a as a gas-liquid mixed phase flow.
[0022]
In the present invention, as shown in FIG. 4, the clearance C between the blade portion 17 a of the impeller 17 and the inner peripheral surface of the casing 14 with which the blade portion 17 a faces is larger than the maximum diameter or the maximum dimension of the carrier 2. It is set large. As a result, the carrier 2 is not caught between the blade portion 17a of the impeller 17 and the casing 14, and damage and wear of the carrier itself can be prevented. In the conventional example, the clearance C is about 1.5 mm when the inner diameter of the casing is 300 mm. In the present invention, the clearance C is set to about 4 mm or more when the inner diameter of the casing is 300 mm. In this case, the carrier 2 has a maximum diameter or maximum dimension of less than 4 mm.
[0023]
Moreover, in this invention, as shown in FIG. 5, the impeller 17 is comprised from the axial flow impeller. The blade portion 17 a of the impeller 17 is covered with a coating material 18. The coating material 18 is made of a resin material such as plastic or rubber. The wing portion 17 a of the impeller 17 is smoothed by the coating material 18. And the impact at the time of contact with the support | carrier 2 can be relieve | moderated by selecting the material of the coating material 18 suitably.
[0024]
In the example shown in FIG. 5, the blade portion surface is smoothed by coating the blade portion of the impeller with a coating material, but the blade portion of the impeller may be formed smoothly by polishing. Further, the entire blade portion of the impeller may be formed by molding a resin material so that the surface of the blade portion becomes smooth.
[0025]
FIG. 6 is an enlarged cross-sectional view of the air chamber casing 16 in the aeration apparatus of the present invention. As shown in FIG. 6, the edge 16a and the ridge 16b of the air chamber casing 16 are formed in a rounded curved surface without corners. Therefore, even if the carrier 2 comes into contact with the edge portion 16a or the ridge portion 16b, the carrier 2 is not damaged or consumed. Although only the air chamber casing 16 is shown in FIG. 6, in the present invention, the edges or ridges of all the members constituting the flow path of the liquid to be treated are formed into rounded curved surfaces without corners. ing. Therefore, it is possible to prevent the carrier 2 from being damaged or consumed while the carrier 2 in the liquid to be treated flows through the flow path in the casing 14.
[0026]
Next, another example of the aeration apparatus 10 will be described with reference to FIG.
FIG. 7 is a sectional view showing another example of the aeration apparatus of the present invention. The aeration apparatus of this example is an upward blowing type.
As shown in FIG. 7, the aeration apparatus 10 includes a casing 34 including a suction casing 32 and a discharge casing 33 that form a flow path of the liquid to be processed, a motor 15 supported by the casing 34, and an air chamber casing 36. And an impeller 17 provided in the flow path of the liquid to be processed formed in the casing 34. An air chamber 39 is formed in the air chamber casing 36, and air or oxygen is supplied to the air chamber 39 through an air supply pipe 5 connected to the blower 4 (see FIG. 1). Yes.
[0027]
In the above-described configuration, when the motor 15 is driven, the processing liquid in the tank containing the carrier 2 flows from the lower suction casing 32 by the rotation of the impeller 17 and flows upward in the flow path in the impeller 17. From the discharge port 33a of the discharge casing 33. On the other hand, the air supplied to the air chamber 39 through the air supply pipe 5 is ejected from the injection port 43 into the liquid to be processed in the flow path in the casing 34, mixed and stirred with the liquid to be processed, and discharged as a gas-liquid mixed phase flow. It is fed into the aerobic tank 1 from the outlet 33a.
Also in the aeration apparatus 10 of the present embodiment, the clearance C of the portion between the blade portion 17a of the impeller 17 and the casing 34 is set larger than the maximum diameter or maximum dimension of the carrier 2. The configuration of the impeller 17 is the same as the example shown in FIG.
[0028]
As described above, in the embodiment shown in FIG. 1 to FIG. 7, by installing the aeration apparatus 10 composed of an underwater aerator instead of the conventional fine bubble aeration apparatus, despite the secular change, Stable oxygen dissolution efficiency can be obtained. As a result, high processing performance can be obtained, and maintenance and inspection work can be greatly reduced.
[0029]
Next, the circulation type nitrification denitrification method using the aerobic treatment tank of the present invention will be described. FIG. 8 is a schematic longitudinal sectional view of an apparatus used for the circulation type nitrification denitrification method.
In FIG. 8, the aerobic tank 1 uses the aerobic tank of the present invention. Reference numeral 25 denotes an oxygen-free tank, and reference numeral 27 denotes an apparatus for separating the carrier and the nitrified circulating liquid. Constituent elements similar to those in the example shown in FIG.
[0030]
With reference to FIG. 8, will be described nitrification denitrification method, wastewater flowing through the flow pipe 7 is separated into the carrier and nitrifying circulating fluid separator 27, anoxic tank through separate nitrification circulating fluid are both pipe 28 25, and after being subjected to denitrification, it flows into the aerobic tank 1 from an inlet provided in the upper part of the wall 29 that partitions the anaerobic tank 25 and the aerobic tank 1.
[0031]
In the aerobic tank 1, a circulating flow is generated by the aeration device 10, and due to the effects described in the embodiment of FIGS. 1 and 2, the nitrification treatment is sufficiently performed, and the treated water flows out through the carrier separator 6. The carrier transfer pump 3 installed in the outlet end, the carrier plus nitrification circulating fluid is conveyed through the pipe 11 to the separator 27 Ru is separated into a carrier and nitrification circulating fluid. The separated nitrification circulating liquid is circulated to the anoxic tank 25 through the pipe 28.
[0032]
【The invention's effect】
As described above, according to the present invention, in the water treatment apparatus using the microorganism-immobilized carrier, the formation of the carrier concentration distribution can be prevented and eliminated, and the oxygen supply rate in the tank is made uniform, so that the whole tank is high. Processing performance can be obtained.
[0033]
In the aeration apparatus of the present invention, the clearance between the blade portion of the impeller and the casing facing the blade portion is set to be larger than the maximum diameter or maximum dimension of the carrier. Therefore, the carrier is not bitten between the blade portion of the impeller and the casing, and the carrier itself can be prevented from being damaged or consumed.
[0034]
Further, in the present invention, since the blade portion of the impeller is covered with a coating material or the blade portion surface is formed smoothly, the carrier contacts the blade portion of the impeller when passing through the impeller. However, the impact at the time of contact can be alleviated, microorganisms such as nitrifying bacteria on the surface of the carrier can be prevented from peeling off, and consumption of the carrier itself can be prevented.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of an aerobic treatment tank of the present invention.
2 is a plan view of FIG. 1. FIG.
FIG. 3 is a cross-sectional view showing an example of an aeration apparatus according to the present invention.
FIG. 4 is a plan view showing an example of an aeration apparatus according to the present invention.
FIG. 5 is an enlarged view of a main part of an impeller in the aeration apparatus of the present invention.
FIG. 6 is an enlarged sectional view of an air chamber casing in the aeration apparatus of the present invention.
FIG. 7 is a cross-sectional view showing another example of the aeration apparatus of the present invention.
FIG. 8 is a schematic longitudinal sectional view of an apparatus used in the nitrification / denitrification method of the present invention.
FIG. 9 is a cross-sectional view showing an example of an aerobic treatment tank using a conventional carrier.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Aerobic tank 2 Carrier 3 Carrier transfer pump 4 Blower 5 Air supply pipe 6 Carrier separator 7 Inflow pipe 8 Outflow pipe 10 Aeration device 12, 32 Suction casing 13, 33 Discharge casing 14, 34 Casing 15 Motor 16, 36 Air chamber casing 17 Impeller 17a Wings 19, 39 Air chamber 18 Coating material 25 Oxygen-free tank 27 Separating device 29 Partition wall
53 Air diffuser

Claims (7)

An aeration apparatus installed in an aerobic treatment tank of sewage having a carrier on which microorganisms held in a floating state are immobilized,
The aeration apparatus includes a casing and an axial flow impeller provided in a flow path of the liquid to be processed formed in the casing, and is rotated in the aerobic processing tank by the rotation of the axial flow impeller. process liquid flows from the casing, flows through the flow path in the axial flow impeller is discharged from the casing into the aerobic treatment tank consists water aerator agitating the aerobic treatment tank, the axial flow vane An aeration apparatus for an aerobic treatment tank for sewage, wherein a clearance between a wing part of a vehicle and the casing facing the wing part is set to be larger than a maximum diameter or a maximum dimension of the carrier.   The aeration apparatus for sewage aerobic treatment tank according to claim 1, wherein a blade portion of the impeller is coated with a coating material.   2. The aeration apparatus for sewage aerobic treatment tank according to claim 1, wherein a surface of a blade portion of the impeller is formed smoothly.   The aeration apparatus for a sewage aerobic treatment tank according to claim 3, wherein a surface of a blade portion of the impeller is smoothly formed by polishing.   The aeration apparatus for a sewage aerobic treatment tank according to claim 3, wherein a surface of a blade portion of the impeller is smoothly formed by molding a resin material.   The aeration apparatus for an aerobic treatment tank for sewage according to claim 1, wherein an edge or a ridge of a member constituting the flow path of the liquid to be treated is formed into a rounded curved surface without corners. In the aerobic treatment tank of sewage having a carrier in which microorganisms held in a floating state are immobilized, one or more aeration devices are arranged at a position where the inside of the tank can be aerated and mixed uniformly,
The aeration apparatus includes a casing and an axial flow impeller provided in a flow path of the liquid to be processed formed in the casing, and is rotated in the aerobic processing tank by the rotation of the axial flow impeller. process liquid flows from the casing, flows through the flow path in the axial flow impeller is discharged from the casing into the aerobic treatment tank consists water aerator agitating the aerobic treatment tank, the axial flow vane A sewage aerobic treatment tank, wherein a clearance between a wing part of a vehicle and the casing facing the wing part is set to be larger than a maximum diameter or a maximum dimension of the carrier.

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