JP2966994B2 - Aeration method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for uniformly mixing and stirring even at the bottom of a deep aeration tank having a depth of more than 10 m and supplying a required amount of air or oxygen to efficiently perform aeration and stirring. It concerns the device.

[0002]

2. Description of the Related Art In the treatment of sewage, there is an aeration method in which air is supplied into a tank and the sewage is stirred as a method for decomposing organic substances in the sewage. Conventionally, there is a device disclosed in Japanese Patent Publication No. 55-29756 as a device for stirring and aerating sewage in a deep tank up to the tank portion. In this, a cylinder is arranged in a tank, and a screw is provided in the cylinder. This causes a downward flow while blowing air into the wastewater in the cylinder, and after reaching the tank bottom, the outer peripheral portion of the cylinder is raised. It is a method of circulating in the tank as countercurrent.

[0003]

When a downward flow is generated by a stirrer in a cylinder installed in a tank and air is blown down to the bottom of the tank while stirring the sewage in the cylinder, 10
In a tank of about several meters, a whole circulation flow in the tank is generated, and required stirring and aeration can be performed. However, when aeration is performed during the downward flow of sewage, a certain amount of upward flow is generated in the cylinder by part of the downward flow caused by the stirrer due to bubbles rising in the cylinder.
This is generally due to the air lift generated by air bubbles, and the generated upward flow is generally about 0.3 m / sec. Therefore, in a deep tank of 10 m or more, in the middle of the downward flow generated by the rotation of the screw, the upward flow due to this air lift force becomes stronger than the downward flow, and discharges into the downward flow and this downward flow. The generated air bubbles did not reach the bottom of the tank, and the downward water flow stopped in the middle of the tank, and uniform stirring and aeration in the tank could not be performed.

According to the present invention, a synergistic action of the aerator and the pump generates a vertical circulating water flow and a swirling water flow in the aeration tank to generate a circulating swirling water flow throughout the entire tank even in a deep tank of more than 10 m or more. It is an object of the present invention to stably supply oxygen and mix and stir, and to uniformly perform desired stirring and aeration up to the bottom of the tank.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above-mentioned object. A draft tube reaching the bottom of a deep aeration tank is provided at the center of the deep aeration tank, and a communication tank is provided above the draft tube. The communication tank draws wastewater into the aeration tank and uses the water level difference between the two tanks to generate a circulating upward water flow from the bottom of the aeration tank to the top, and a self-priming type arranged at the top of the aeration tank. The gist of the present invention is that a swirling water flow is generated while aerating with a screw-type aerator, so that uniform aeration and agitation are efficiently performed over the entire tank. Further, in the aeration apparatus of the present invention for carrying out this method, a draft tube reaching the bottom of the deep aeration tank is provided, and a communication tank is provided above the draft tube and a communication tank is provided in the communication tank. A pump that pumps out the sewage in the tank and creates a water level difference so that the water level is lower than the water level in the aeration tank,
The gist is that an aerator for generating a swirling water flow is installed in the aeration tank.

[0006]

[Action] A draft tube reaching the bottom of the deep aeration tank is provided at the center, and a communication tank is provided at the top of the draft tube. When the pump and the aerator are operated, the water level in the communication tank is increased by pumping up. The water level drops below the water level in the aeration tank, and a predetermined water level difference occurs. Due to this water level difference, the water at the bottom of the tank rises in the draft tube and is guided into the communication tank. By this pump-up, a circulating upward water flow is generated between the bottom of the tank and the upper part of the tank. Further, by the operation of the plurality of self-priming screw type aerators arranged in a tomography, a swirling flow is generated and aerated in the upper water area in the aeration tank at the outer periphery of the communication tank. Even in a deep aeration tank due to the synergistic action of this vertical circulating water flow and the swirling water flow, the water in the tank flows down while swirling from the top of the tank toward the bottom of the tank, and the water throughout the tank is uniformly agitated and aerated. Done in

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. 1 and 2 show a first embodiment of the aeration apparatus of the present invention. In the figure, reference numeral 1 denotes an aeration tank having a required size and a rectangular or circular shape having a depth of 10 m or more, preferably 20 to 30 m, and other shapes. A draft tube 2 for guiding is provided, and a communication tank 3 is provided above the draft tube 2 so as to be isolated from the inside of the aeration tank. The draft tube and the communication tank are integrally provided by directly connecting the upper end of the draft tube 2 to the bottom of the communication tank 3 or by projecting the upper end of the draft tube a little into the communication tank as shown in the drawing. The bottom of the tank and the inside of the communication tank 3 are communicated via the draft tube 2, and the bottom of the aeration tank 1 is formed such that sludge and the like settled downward from the inner peripheral side of the tank to the lower part of the lower end of the draft tube. Has an inclination angle θ such that the center is lowered so as to flow downward.

Further, a pump or a submersible pump 4 is installed in the communication tank 3 to pump water in the communication tank and discharge the water to the upper part of the aeration tank, so that the water level in the communication tank and the water level in the aeration tank are adjusted. A predetermined water level difference is generated in the relationship of The difference between the two water levels is determined in advance by the pumping capacity of the pump 4, and the water at the bottom of the tank is raised in the draft tube and guided into the communication tank using the difference in water level.

Further, a plurality of aerators 5 are provided so as to generate a water flow swirling in the outer peripheral portion of the communication tank in the tank while aerating the upper layer water of the aeration tank 1. This aerator 5 is a self-priming screw type, and a screw 51 provided at the tip of a hollow shaft by a motor.
The air is sucked in from the upper intake hole by the negative pressure generated in the screw tip water area by rotating the, and is discharged in the screw tip water area, thereby generating a swirling flow while stirring the water in the tank. Aerate.

Therefore, when the pump 4 and the aerator 5 are operated in the aeration apparatus configured as described above, the water level in the communication tank falls below the water level in the aeration tank due to the pump-up, and a predetermined water level difference occurs. Due to this water level difference, the water at the bottom of the tank rises in the draft tube 2 and is guided into the communication tank. By this pump-up, a circulating water flow is generated between the bottom of the tank and the upper part of the inside of the tank, and the aerators 4 are arranged in a torsion. Occurs and is aerated. The water in the aeration tank flows down while rotating from the tank top toward the tank bottom by the synergistic action of the vertical circulating water flow and the swirling water flow, and the water in the entire tank is uniformly stirred and aerated.

FIG. 3 shows a second embodiment of the aeration apparatus according to the present invention.
In the embodiment, in the first embodiment of the aeration apparatus of the present invention shown in FIGS. 1 and 2, a spiral screw blade 6 is provided on the outer peripheral surface of the draft tube 2 so as to protrude over a part or the entire length of the draft tube, and The draft tube 2 is turned by a turning means 7 provided at the upper part. Accordingly, when the aerator 5 and the pump 4 are driven, the draft tube 2 is also swirled to forcibly force a downward flow in the tank, thereby enhancing the circulating water flow and the swirling water flow in the upper and lower portions in the tank. .

Further, a third embodiment of the aeration apparatus of the present invention shown in FIG. 4 is a first embodiment of the aeration apparatus of the present invention shown in FIGS.
In the embodiment, a stirrer 8 for generating an upward flow is installed in the draft tube 2, and by rotating a screw 81 of the stirrer 8, the upward flow rate generated in the draft tube due to a difference in water level is reduced. It has been strengthened to strengthen the circulating water flow.

[0013]

According to the present invention, a draft tube reaching the bottom of the deep aeration tank is provided at the center of the deep aeration tank, a communication tank is provided above the draft tube, and sewage is supplied from the communication tank into the aeration tank. Utilizing the difference in water level between the two pumping tanks to generate a circulating upward water flow from the bottom of the aeration tank to the top, and to generate a swirling water flow while aerating with a self-priming screw type aerator installed at the top of the aeration tank Since it is made to carry out, it has the advantage that even the deep aeration tank of 20 to 30 m can easily agitate and aerate the wastewater at the bottom of the tank.

[Brief description of the drawings]

1 is a cross-sectional view showing a first embodiment of the aerator of the present invention.

FIG. 2 is a plan view of the same.

FIG. 3 is a sectional view showing a second embodiment of the aeration apparatus of the present invention.

FIG. 4 is a sectional view showing a third embodiment of the aeration apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Aeration tank 2 Draft tube 3 Communication tank 4 Pump 5 Aerator

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C02F 3/22 B01F 3/04 B01F 7/16

Claims (2)

(57) [Claims] 1. A dough that reaches almost the bottom of the deep aeration tank at the center.
Arrange the raft tube and the top of this draft tube
A communication tank was provided, and sewage was pumped from the communication tank into the aeration tank, and a circulating upward water flow was generated from the bottom of the aeration tank to the upper part using the difference in water level generated between the two tanks, and was disposed at the top of the aeration tank. An aeration method characterized in that a swirling water flow is generated while aerating with a self-priming screw-type aerator, so that uniform aeration and agitation are efficiently performed over the entire tank. 2. A draft tube reaching the bottom of the deep aeration tank is provided substantially at the center of the deep aeration tank. A communication tank is provided at the top of the draft tube. An aerator comprising: a pump for generating a water level difference so as to be lower than an internal water level; and an aerator for generating a swirling water flow in an aeration tank.