JPH02245291A - Operation of aerator - Google Patents

Abstract

PURPOSE:To carry out efficient operation in the aerator, in which sewage is agitated and aerated, by detecting the amt. of scum on the water surface and water level to control the air supply and selecting between the scum crushing priority operation and aeration priority operation. CONSTITUTION:The aerator 2 is set on a rack 3 at the bottom of a sewage storage pit 1. The aerator 2 is formed by an impeller 22 to be driven by a submergible motor 21, an air pipe 23 and a flow straightening cylinder 28. The rotating shaft of the motor 21 is hollowed, air is sucked from the air pipe 23 opened over the water surface at all times and discharged into the cylinder 28 to aerate the sewage sucked from a suction port 29, and the sewage is discharged from a discharge port 30 and circulated in the pit 1. While less than a specified amt. of scum is present on the sewage surface, aeration priority operation is continued, and the water is discharged by a pump (not shown in the figure). When the water level is lowered below a specified value or the scum amt. is increased, aeration is stopped, the scum is strongly sucked into the cylinder 28, and scum crushing priority operation is carried out. Consequently, aeration and scum crushing are carried out efficiently and continuously.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention performs aeration when scum is not detected, and stops ventilation to the aeration device when scum is detected to suction and crush floating scum, thereby increasing the efficiency of wastewater. This is a method for performing targeted aeration and scum removal.

[Conventional technology]

Equipment for agitating and aerating the wastewater is installed in building bits and pump wells where wastewater is temporarily stored in the basement of buildings and pumped up and drained while being aerated. This aeration device is in continuous aeration operation.

[Invention tries to solve! ! ! 1) Sewage is sucked in by a blade rotated by a motor, and air is introduced from the ventilation pipe using the negative pressure generated at the tip of the blade or part of the discharge pipe to aerate and float on the surface of the wastewater. It also sucks up the scum and crushes it.

Therefore, it is necessary to increase the flow rate of surface wastewater into the aerator casing, which is necessary for scum suction, to be above a certain limit. However, when the water level is high, it is difficult to obtain an inflow velocity higher than necessary. In addition, in order to suck scum from all over the water surface into the line machine, it is necessary to generate a swirling flow within the bit using the inner wall of the bit, etc., and guide the scum to the vicinity of the scum suction port. However, during aeration operation without restricting the amount of ventilation, there is a drawback that scum accumulates and grows in the corners because the swirling flow generated within the bit is insufficient.

The present invention aims to solve the above-mentioned drawbacks by detecting the presence or absence of floating scum and selectively switching the operation of the same aeration device between an aeration intensive operation and a scum crushing intensive operation. .

[Means to solve the problem]

The aeration equipment is equipped with the ability to crush floating scum, and when it detects that more than a predetermined amount of scum has occurred on the wastewater surface, it restricts ventilation and stops the aeration intensive operation, and also suctions and crushes the floating scum. Selectively switch to scum crushing focused operation.

〔Example〕

The method of operating the aeration system of the present invention will be explained below based on the illustrated embodiment.

In the figure, 1 is a building bit, a pump well, and a tank that temporarily stores wastewater for treatment (hereinafter referred to as a sewage treatment tank).
At the bottom of this sewage treatment tank 1, an aeration unit 2 is installed either directly or via a pedestal 3.

This aeration device 2 can adopt various types of mechanisms, but in the illustrated embodiment, as shown in FIG. 23 and a rectifying tube 28.

The underwater motor 21 is driven by a hydraulic, electric or other power source, and a similarly hollow stirring blade shaft 25 is directly connected and fixed to a hollow motor shaft 24 of the underwater motor 21. The stirring blade 22 is formed by integrally providing a stirring blade base body 26 having a spiral shape or other shape suitable for aeration around the outer periphery of a hollow shaft 25.

The motor shaft 24 of the underwater motor 21 is made hollow with a ventilation hole 27 having a required cross-sectional area, so that the inside of the motor shaft can be ventilated, and the underwater motor shaft 24
A ventilation pipe 23 is connected to the opposite output side, that is, the side opposite to the stirring blade, and the tip of the ventilation pipe 23 is always located above the water surface.
This allows the stirring blade shaft to be ventilated from the inside of the motor shaft. Further, the stirring blade 22 has rectification 1! Stored in I2B (draft tube), this!
The first flow cylinder 28 has a suction port 29 widened in a trumpet shape at the upper end, and a blowout port 30 opened in the longitudinal direction of the stirring blade.
As the agitating blade rotates, wastewater is sucked into the rectifying cylinder through the suction port 29, atomized by the blade, and stirred and discharged into the water. Of course, the water is also stirred by the blades, and aeration is thereby performed. At this time, the sewage is sucked in through the suction port 29 of the straightening tube 28 and discharged from the outlet, and the sewage circulates within the tank.

This RS air intensive operation is carried out as described above by operating the aeration device 2 when scum is not generated on the waste water surface more than a predetermined amount. During this aeration-intensive operation, the aeration pulp is removed, air is self-suctioned into the wastewater, and aeration is produced once. After waiting for this intensive aeration operation for a predetermined time, the intensive aeration operation is stopped and the drainage pump is driven to drain the aerated wastewater, or the aeration intensive operation and drainage are used together.

When it is detected that the amount of scum generated on the water surface has reached a predetermined amount or more, the ventilation to the aeration device is restricted.
As the scum suction force into the aerator increases and the swirling flow inside the bit also increases, the floating scum that has begun to solidify is sucked into the straightening cylinder, crushed by the stirring blades, and discharged into the tank together with the wastewater again into the water. Qfi and is sucked into the pump and discharged outside the tank. By restricting ventilation in this way, the aeration system rIjL-
When operated, it switches from aeration focused operation to scum crushing focused operation.

In addition, as another method of suctioning and crushing scum, there is a method of increasing the scum suction function by keeping the water level in the pit at a low level. In other words, in order to efficiently suck up the scum floating on the water surface, it is necessary to set the water level to a level where a thin vortex occurs, but as shown in Figure 3, the probability of vortex generation increases when ventilation is stopped, and it also increases even at low water levels. Therefore, it is possible to improve the scum suction function even by maintaining a low water level while continuing ventilation. Of course, stopping ventilation and maintaining a low water level are efficient. Note that maintaining a low water level is possible by frequently operating the drainage pump after detecting a low water level.

Furthermore, instead of changing and maintaining the water level itself, it is also possible to lower the apparent water level by raising and lowering the aeration device and placing it just below the liquid level.

Also, as means for detecting the occurrence of scum, a television camera 4. There is a method using an optical sensor 5 or the like. This method is shown in FIG. 4. When using this television camera 4, scum detection can be performed when the scum area exceeds a set amount or when the ratio of a certain scum area to a layer surface area exceeds a set value. can.

Further, when using the optical sensor 5, when the amount of light reflected by the dirty water surface falls below a set value, scum generation is detected, and in this case, one or more optical sensors 5 are used.

Another scum detection method involves indirectly detecting scum. This is because the amount of scum generated is often proportional to time, and it can be considered that the amount of scum generated is a constant amount depending on the passage of time. By applying this principle, it is decided in advance to close when scum is generated, and the aeration equipment is switched alternately between the aeration intensive operation and the scum crushing intensive operation, and an example of this is shown in Fig. 5. B is for aeration operation.
indicates the scum crushing operation, and this scum crushing operation switching timing may be after time management rather than detection, or may be linked to pump activation after detection.

In addition to the structure shown in FIG. 2, the aeration device according to the present invention has similar functions and effects in the device shown in FIG. 6, and its structure is not limited.

In the embodiment described above, the scum amount is detected and the operation is switched to scum crushing operation, but in order to effectively crush the scum, it is desirable to link the operation with the first layer, and furthermore, when the water level is low, It is also fully possible to switch only to scum crushing operation.

〔Effect of the invention〕

The method of operating the aeration device of the present invention includes providing the aeration device with the ability to crush floating scum, and when detecting the occurrence of scum on the surface of wastewater in excess of a predetermined amount, stopping the aeration and stopping the aeration focused operation, Since the system selectively switches to scum crushing focused operation, which suctions and crushes floating scum, upon detection of scum generation, it is possible to eliminate residual scum in the pit and perform aerated drainage of sewage, resulting in continuous operation. It has the advantage that operation can be carried out safely and that the work of discharging scum, which is carried out periodically as in the past, can be omitted.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram of an embodiment showing the aeration method of the present invention;
Figure 2 is a cross-sectional view of the aeration system, Figure 3 is a graph showing the relationship between water depth and probability of vortex generation, Figure 4 is a diagram showing different embodiments of scum generation detection, and Figure 5 is a graph showing the relationship between scum generation and time. A graphical representation of the method of detection, FIG. 6 shows different embodiments of the aeration device. 1 is a bit, 2 is an aeration device, 22 is a stirring blade, 23 is a ventilation pipe, 4 is a television camera, 5 is an optical sensor Patent applicant Hitachi Kiden Kogyo Co., Ltd. Figure 1 Figure 6 (A) (C) UT゛

Claims (3)

[Claims] (1) In a device that stirs and aerates wastewater while aerating the wastewater, a scum crushing focused operation is performed in which a fixed amount of scum on the surface of the wastewater is detected by a scum amount detection means and/or the aeration amount is limited by water level detection; A method for operating an aeration device, characterized by selectively performing an aeration focused operation in which the aeration amount is not limited. (2) The method of operating an aeration system according to claim 1, characterized in that, based on the detection, a scum crushing intensive operation is performed while maintaining a low water level, and an aeration intensive operation is operated regardless of the water level. (3) A scum crushing focused operation in which the amount of ventilation is limited by the detection and is operated while maintaining a low water level, and a scum crushing operation that does not limit ventilation;
2. The method of operating an aeration system according to claim 1, further comprising selectively performing an aeration focused operation regardless of the water level.