JPH05261388A - Operating method for aerator - Google Patents

Abstract

PURPOSE:To prevent material from being stuck to a hollow shaft and to efficiently perform aerating operation for a long period. CONSTITUTION:A screw 3 is provided to the lower end of a hollow shaft 2. Water flow is generated by rotation of the screw 3. Air is self-primed through the inside of the hollow shaft 2 by negative pressure generated in the tip part of the screw 3 and aeration is performed. A suction pipe 4 and a control valve controlling quantity of airflow are equipped to the rear end of a motor 1. The quantity of air is increased, decreased and regulated in accordance with inflow load and continuous operation is performed. Operation is stopped together therewith at least in an extremely short time for one time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, when continuously operating a self-priming aerator, removes sludge and the like adhering to the inside of a hollow shaft that serves as an air passage so that it can always be operated with stable power and wind force. The present invention relates to a method of operating an aeration device.

[0002]

2. Description of the Related Art As a treatment method for removing organic substances in wastewater, there is a method of agitating wastewater and aerobically treating it by aeration. The conventional screw-type self-priming aeration device is an aerobic operation device that operates exclusively in aerobic operation, that is, supplies air to the wastewater to decompose and treat organic substances in the wastewater. When the load of the aeration device is low, or when nitrogen in sewage, so-called denitrification process is performed, it is necessary to narrow down the aeration amount of the aeration device. For this reason, an adjusting valve is installed in the aeration device to adjust the amount of ventilation.

[0003]

Therefore, when continuously operating the self-priming aerator, the hollow shaft allows the air / water balance point to vent when the air flow rate is set to 5% or less of the valve fully opened by the air flow control valve. Inside the hollow shaft, sewage and sludge intrude, which adheres at the gas-liquid interface and grows further, narrowing or blocking the aeration passage in the hollow shaft, reducing the aeration volume, It reduces the aeration efficiency during operation.

It is an object of the present invention to prevent deposits on the hollow shaft and to perform efficient aeration operation for a long period of time even when the self-priming aeration apparatus is continuously operated and the ventilation amount is controlled. .

[0005]

The present invention has been made to achieve the above object. A screw is provided at the lower end of a hollow shaft, and a water flow is generated by the swirling of the screw, and a negative pressure is generated at the tip of the screw. In an aerator that self-primes air through the hollow shaft by pressure, an intake pipe and a control valve for controlling the air flow rate are provided at the rear end of the motor, and the air volume is adjusted to increase or decrease according to the inflow load and continuous operation is performed. The main idea is to stop the operation at least during a very short time.

[0006]

[Operation] A self-priming aeration system that uses the negative pressure generated in the water area at the tip of the screw due to the rotation of the screw to release the air taken in through the intake pipe, the air flow control valve, and the hollow shaft into the water. When the device is continuously operated, the operation is stopped for at least 5 to 30 minutes per day. As a result, the gas-liquid interface inside the hollow shaft can be changed, and the sludge that sticks to the inside of the hollow shaft during continuous operation can be redissolved in the wastewater again, and the air flow inside the hollow shaft can be kept normal and efficient. Aeration can be performed.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the illustrated embodiments. As shown in FIG. 1, a screw type self-priming aerator A used in the treatment of sewage such as sewage and industrial wastewater has a motor 1 and a hollow shaft of a required length directly connected to the hollow motor shaft of the motor 1. 2, a screw 3 provided at the tip of the hollow shaft 2, an intake pipe 4 provided on the opposite side of the motor shaft, and a control valve 5 for controlling the air flow rate.

The hollow shaft 2 has a required length and strength, and when the aeration device A is arranged in an aeration tank or a water channel so as to have a required penetration angle with respect to the sewage surface, a predetermined depth from the water surface. The length of the hollow shaft is fixed appropriately, and the screw 3 is fixed to the tip of the hollow shaft as necessary. Teflon coating may be applied near the surface.

The motor shaft of the motor 1 is connected to the base end side of the hollow shaft 2 via a shaft joint 6, and the screw 3 is rotated by the drive of the motor 1 via the hollow shaft 2 to dispose of in the dirty water. In addition, a negative pressure is generated in the screw tip water area, and by utilizing this negative pressure, the air is finely divided into the screw tip water area through the hollow motor shaft and the hollow shaft 2 via the intake pipe 4 and the air flow control valve 5. Supply it as bubbles. In this case, although not shown, an electric control circuit may be provided in the motor 1 so that the rotation speed of the motor is controlled to adjust the rotation speed of the screw so that aeration and agitation can be adjusted.

The motor shaft is rotatably supported by a casing of the motor 1 via bearings, and an intake pipe 4 is provided at the end of the motor shaft. Further, a control valve 5 is provided on the intake pipe 4, and the control valve 5 is electrically operated to open and close to adjust the ventilation amount. The control valve 5 is set to have a ventilation amount set during the aerobic operation set at the previous time, and can be adjusted according to the load. During the anaerobic operation, the control valve 5 is controlled to a fully closed state or a state close to a fully closed state.

Therefore, in the aeration apparatus constructed as described above, when the screw 3 at the tip of the hollow shaft 2 which is driven by the motor 1 and is rotated is driven, the hollow shaft is driven by the negative pressure generated in the screw tip water region by the propelling force of the screw. Air is sucked from the intake pipe and control valve on the side opposite to the output shaft of the hollow shaft of the motor that is directly connected to, and is sent out into the water. The control valve 5 such as the electric ball valve provided on the intake side is adapted to the inflow load. The opening / closing operation is performed to increase / decrease the air amount and adjust the air amount to the optimum amount.

When the aeration device is continuously operated and the control valve 5 is squeezed within 5% of the fully opened state, the air-water balance point is inside the hollow shaft, and the air-liquid boundary surface enters the hollow shaft. Sludge adheres and dries and grows. By completely stopping the aeration device that is continuously operated to remove this, for a predetermined period of one day, sewage penetrates into the hollow shaft up to the liquid level position of the aeration tank, and the gas-liquid boundary surface floats. As a result, the sludge adhering to the hollow shaft and growing dry is completely submerged. As a result, the adhered sludge is again dissolved in water and peeled off from the inner peripheral surface of the hollow shaft.

It is sufficient for the aeration apparatus to completely stop for 5 to 30 minutes in this one day, and if the stopping time is longer than this, the aeration and stirring efficiency will decrease. Further, it is possible to stop the aeration device periodically in a predetermined manner,
It is also possible to control so as to stop under the condition that the air amount is 50% or more.

The graph of FIG. 2 shows the relationship between the aerobic time ratio and the TN removal rate depending on the presence or absence of anaerobic stirring and the presence or absence of suspension. The removal rate is about 10% higher with anaerobic stirring, and it can be seen that there is no difference due to the presence or absence of suspension. 4 and 5 show changes in power and air volume during continuous operation and during 5 minutes / day rest. It can be seen that during continuous operation, power increases and air volume decreases, resulting in performance degradation. FIG. 6 shows changes in the bottom flow velocity after the aerator is stopped. It becomes less than 10 cm / s in about 30 minutes and sludge begins to accumulate. Therefore, it is desirable that the stop time be within 30 minutes.

[0015]

According to the method of operating the aeration apparatus of the present invention, a screw is provided at the lower end of the hollow shaft, a water flow is generated by the swirling of the screw, and the negative pressure generated at the tip of the screw causes air to flow through the hollow shaft. In the aeration device that sucks air, an intake pipe and a control valve for controlling the air flow rate are provided at the rear end of the motor, and the air amount is adjusted to increase or decrease according to the inflow load, and continuous operation is performed. Since it is configured to stop, it has an advantage that sludge and the like can be prevented from adhering to the inside of the hollow shaft and that the operation can be performed with a stable aeration amount and power.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of an aeration device of the present invention.

FIG. 2 is a graph showing a relationship between an aerobic time ratio and a TN removal rate.

FIG. 3 is a graph showing a power ratio.

FIG. 4 is a graph showing an air volume ratio.

FIG. 5 is a graph showing a bottom flow velocity ratio.

[Explanation of symbols]

 1 Motor 2 Hollow shaft 3 Screw 4 Intake pipe 5 Ventilation control valve

[Procedure amendment]

[Submission date] December 8, 1992

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Added

[Correction content]

[Fig. 2]

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

[Correction method] Added

[Correction content]

[Figure 3]

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 4

[Correction method] Added

[Correction content]

[Figure 4]

[Procedure amendment 4]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 5

[Correction method] Added

[Correction content]

[Figure 5]

Claims (3)

[Claims] 1. An aerator, in which a screw is provided at the lower end of a hollow shaft, a water flow is generated by the swirling of the screw, and the negative pressure generated at the tip of the screw self-sucks air through the hollow shaft. Aeration that is equipped with an intake pipe and a control valve for controlling the air flow rate at the end, and adjusts the air volume according to the inflow load to continuously operate and at the same time stop the operation only at an extremely short time. How to operate the device. 2. The method for operating an aeration device according to claim 1, wherein the operation of the aeration device is stopped under the condition that the air amount is 50% or more. 3. The operation of the aeration device is stopped for 5 to 3 times a day.
The method for operating the aeration apparatus according to claim 1 or 2, wherein the operating time is 0 minutes.