JPH0585237B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for aeration in the case where scum is not detected.
In scum detection, the present invention relates to a method for efficiently aerating wastewater and removing scum by suctioning and crushing floating scum by stopping ventilation to the aeration equipment, etc.

[Conventional technology]

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

[Problem to be solved by the invention]

The sewage is sucked in by a blade rotated by a motor, and the negative pressure generated at the tip of the blade or part of the discharge pipe is used to introduce air from the ventilation pipe and aerate it, as well as to remove scum floating on the surface of the sewage. It is also sucked in to crush 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 the scum from all over the water surface into the machine, it is necessary to generate a swirling flow in the pit using the inner wall of the pit, 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 in the pit is insufficient.

In the present invention, the presence or absence of this floating scum is detected and the operation of the same aeration device is selectively switched between an aeration intensive operation and a scum crushing intensive operation,
The purpose is to solve the above-mentioned drawbacks.

[Means to solve the problem]

The aeration equipment is equipped with the ability to crush floating scum,
When it is detected that more than a predetermined amount of scum is generated on the waste water surface, ventilation is restricted to stop the aeration intensive operation, and the system selectively switches to a scum crushing intensive operation that suctions and crushes floating scum.

〔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 tank such as a building pit or a pump well that temporarily stores wastewater for treatment (hereinafter referred to as a sewage treatment tank), and an aeration device 2 is installed directly at the bottom of this sewage treatment tank 1, or a mount 3 is installed. Installed via.

This aeration device 2 can adopt various types of mechanisms, but in the illustrated embodiment, as shown in FIG. 23 and rectifier tube 28
It's getting more and more familiar.

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 hollow with a ventilation hole 27 having a required cross-sectional area, so that the inside of the motor shaft can be ventilated.
A ventilation pipe 23 is connected to the opposite output side of the underwater motor shaft 24, that is, the side opposite to the stirring blade, and the tip of the ventilation pipe 23 is arranged so as to be always above the water surface. The stirring blade shaft is electrically connected to the ventilation hole 27, and the inside of the stirring blade shaft can be ventilated from the inside of this motor shaft. Further, the stirring blade 22
is stored in the rectifier tube 28 (draft tube),
This straightening cylinder 28 has a suction port 29 which is widened in the shape of a flap at the upper end, and an air outlet 30 that opens in the long axis direction of the stirring blade.
The wastewater is sucked through the rectifying cylinder, atomized by the blades, and then 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 aeration focused operation is carried out as described above by operating the aeration device 2 when no more scum is generated on the waste water surface than a predetermined amount. During this aeration intensive operation, the ventilation valve is opened and air is self-suctioned into the wastewater to perform aeration. After carrying out this intensive aeration operation for a predetermined period of time, the intensive aeration operation is stopped and the drainage pump is driven to drain the sewage after aeration, or
Combine intensive aeration operation and drainage.

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 aerator is restricted, the scum suction force into the aerator increases, and the swirling flow in the pit increases, so that solid The floating scum that has begun to harden is sucked into the straightening cylinder, crushed by the stirring blade, discharged into the tank together with the waste water, suspended in the water, and sucked into the pump and discharged out of the tank. When the aeration device is operated with ventilation restricted in this way, the aeration intensive operation is switched to the scum crushing intensive 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 vortices occur, 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.

Further, as means for detecting the occurrence of scum, there is a method of directly using a television camera 4, an optical sensor 5, etc. This method is shown in FIG. When using this television camera 4, scum can be detected when the scum area exceeds a set amount or when the ratio of a certain scum area to the water surface area exceeds a set value.

In addition, when using the optical sensor 5, if the amount of light reflected by the dirty water surface falls below a set value, scum generation is detected; in this case, the optical sensor 5
Use 2 or more.

Another scum detection method involves indirectly detecting scum. This is because the amount of scum generated is often proportional to time, and can be seen as a constant amount of scum generated over time. Applying this principle, the scum generation time is determined in advance and the aeration equipment is switched alternately between the aeration intensive operation and the scum crushing intensive operation.
As shown in the figure. In this figure, A is the aeration operation, B is
indicates scum crushing operation. Note that 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 devices shown in FIG. 6, and the structure is not limited thereto.

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 scum, it is desirable to link the operation with the water level, 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 for operating an aeration device of the present invention includes equipping 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, The scum crushing intensive operation, which suctions and crushes floating scum, is selectively switched to when the occurrence of scum is detected, so that no scum remains in the pit and aeration and drainage of sewage can be performed, resulting in continuous operation. It has the advantage that operation can be carried out safely and that the work of discharging scum that is regularly performed as in the conventional method can be omitted.

[Brief explanation of the drawing]

Fig. 1 is a schematic explanatory diagram of an embodiment of the aeration method of the present invention, Fig. 2 is a cross-sectional view of the aeration device, Fig. 3 is a graph showing the relationship between water depth and eddy generation probability, and Fig. 4 is a scum FIG. 5 is a graph showing a method for detecting scum generation over time, and FIG. 6 is a diagram showing different embodiments of an aeration device. 1 is a pit, 2 is an aeration device, 22 is a stirring blade,
23 is a ventilation pipe, 4 is a TV camera, and 5 is a light sensor.

Claims (1)

[Scope of Claims] 1. A scum crusher that operates with a fixed amount of scum on the surface of sewage detected by a scum amount detection means and/or with a limited aeration amount by water level detection in an apparatus that aerates and aerates wastewater while aerating it. A method for operating an aeration system, characterized by selectively performing focused operation and focused aeration operation in which the aeration amount is not limited. 2. The method of operating an aeration system according to claim 1, wherein the detection selects between a scum crushing focused operation in which the water level is maintained at a low level and an aeration focused operation in which the water level is maintained regardless of the water level. 3. It is characterized by selectively performing a scum crushing intensive operation in which the aeration amount is limited by the detection and operated while maintaining a low water level, and an aeration intensive operation in which the aeration is not restricted and is operated regardless of the water level. A method of operating an aeration device according to claim 1.