JPH027672Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a scum discharge device that is applied to batch-type activated sludge treatment in which the steps of aeration, precipitation, and discharge are repeated in a single tank.

[Conventional technology]

Conventionally, in batch-type activated sludge treatment, the sedimentation supernatant liquid is discharged after the precipitation step, but in this case, scum may be floating in the treatment tank. However, batch-type activated sludge treatment equipment, which repeats the steps of aeration, precipitation, and discharge in a single tank, has drawbacks such as the scum removal mechanism becoming extremely complex because the water level in the tank changes. .

[Summary of the invention] This invention was made to solve the above-mentioned drawbacks, and the water level can be lowered by swinging on the water surface while opening the scum collection port below the water surface. It is an object of the present invention to provide a scum discharge device that can effectively eliminate scum from a batch type activated sludge treatment tank in which the steps of aeration, precipitation, and discharge are repeated in a single tank with fluctuations.

[Example of idea]

An embodiment of this invention will be described below with reference to the drawings.

Inside the batch type activated sludge treatment tank 1, which repeats the steps of aeration, precipitation, and discharge, there is a decanter 2 that moves up and down and discharges the supernatant liquid during the discharge process, and a decanter 2 that moves up and down to discharge the supernatant liquid during the discharge process.
A scum discharge device 3 for discharging scum on the water surface is provided.

The decanter 2 includes a rotatable shaft pipe 4,
It consists of a discharge pipe 5 connected to this, an overflow pipe 6 attached to the free end of the discharge pipe 5 and having an overflow port 6a, and a decanter float 7. Therefore, when the overflow pipe 6 is lowered, the supernatant liquid in the processing tank 1 flows into the overflow pipe 6 through the overflow port 6a, and is discharged to the outside via the shaft pipe 4. When the overflow pipe 6 reaches LWL, it is detected by a detection means such as a limit switch or a water level gauge, and a signal is sent to a rotating means (not shown). 6 is H.
It is rotated above the liquid level of WL. In this state, the supernatant liquid in the treatment tank 1 is not discharged, and the discharge process is completed.

Scum discharge device 3 that discharges scum on the water surface
The scum discharge pipe 10 penetrates through the processing tank wall 1a and communicates with the outer scum pit 9 via the scum discharge valve 8, and the scum discharge pipe 10 is connected to the scum discharge pipe 10 via a rotation joint 11 so as to be able to swing freely in the vertical direction. connected,
A scum collection pipe 12 is provided with a scum collection port 12a at its free end, and is attached near the free end of this scum collection pipe 12, and when floating on the water surface, opens the scum collection port 12a below the water surface. Scum collection tube 1
It has a float 13 that supports 2.

The scum discharge valve 8 is connected to the overflow pipe 6 of the decanter 2.
It is released by a signal issued at the end of the discharge process when the water reaches LWL. The scum pit 9 where scum is discharged is provided with a scum collection basket 14 and a pump 15, and the scum discharged from the scum discharge pipe 10 is collected by the scum collection basket 14. Collection basket 1
The supernatant liquid that flows down from the scum pit 9 and is stored therein is discharged out of the system by the pump 15.

Further, as shown in FIG. 2, a stopper 16 whose vertical position can be adjusted may be provided as necessary to lock the scum collection pipe 12 so that it does not fall below the LLWL.

[Effect]

Next, the operation of this invention will be explained.

In the treatment tank 1, the steps of aeration, precipitation, and discharge are repeated, and the wastewater flowing in during the aeration period by an aeration device (not shown) or at any time is treated with activated sludge.

In the discharge process, the decanter 2 discharges the supernatant liquid until it reaches the LWL level, and when it reaches the LWL level, the rotation means (not shown) that receives a signal from the detection means lowers the HWL level. It is rotated upward and the discharge process is completed. In addition, processing tank 1
The sludge inside is extracted at an appropriate time.

Here, when the discharge process is completed, the scum discharge valve 8 is opened by the same signal as the command to the rotating means, and discharge of the scum is started. Here, the opening of the scum discharge valve 8 is defined as the point at which the discharge process ends. This is because while the decanter 2 is discharging the supernatant liquid, the flow of water on the surface of the treated water is directed toward the overflow port 6a, and the scum is also collected near the decanter float 7, so the scum collection port It is difficult to collect scum from 12a, and there is a risk that a large amount of supernatant liquid will be discharged. Additionally, if both the decanter 2 and the scum discharge device are opened at the same time during the discharge process, the flow on the surface of the treated water will be disturbed.
This is because there is a risk that scum may be discharged from the decanter 2 and supernatant liquid may be discharged from the scum discharge device. With this invention, such problems do not occur at all. At this time, the scum discharge pipe 12
The scum discharge pipe 12 is supported by a float 13 such that the scum collection port 12a opens at a predetermined distance below the water surface, and the scum discharge pipe 12 is supported to be able to swing freely around the rotation joint 11. While discharging smoothly, it descends as the water surface descends.

Then, after a predetermined period of time (for example, about 3 to 5 minutes) has elapsed, the scum discharge valve 8 is closed by the timer, the scum discharge is completed, and a new aeration process is started. Here, as mentioned above, the stopper 16
Accordingly, the scum collection pipe 12 may be prevented from descending below LLWL.

Note that scum discharge may not be performed every time, but may be performed as needed.

In addition, in the aeration process, if aeration is performed while the scum collection pipe 12 is supported on the water surface, the scum collection pipe 12 will swing greatly and there is a risk of damage. It is best to start after

[Effect of idea]

As described above, according to this invention, a scum discharge pipe is connected via a scum discharge valve to the scum pit of a treatment tank that repeats the batch activated sludge treatment process, and the scum discharge pipe is connected to the scum discharge pipe so as to be able to swing vertically. a scum collection tube which is housed in the treatment tank and has a scum collection port at its free end; and a float which is attached to the scum collection tube and floats on the liquid surface in the treatment tank. The structure is extremely simple, and since the scum collection port is kept submerged when the float is floating on the liquid surface, opening the scum discharge valve allows the liquid to be removed. The scum floating near the surface can be caused to flow into the scum collection pipe from the scum collection port and discharged into the scum pit through the scum collection pipe, and in particular, the scum can be discharged at a specific time suitable for the discharge. It can be done within.

In other words, the scum discharge valve is not just a manual opening/closing valve, but is opened by inputting a signal when the water level in the treatment tank reaches a predetermined level due to water level fluctuations and the discharge process is completed. The valve is designed to close after a predetermined period of time has elapsed, so
The scum generated in the treatment tank where the water level fluctuates rapidly can be efficiently discharged without removing excess supernatant liquid.

In addition, the scum discharge valve will close after a predetermined period of time has elapsed from the time it opens (starts scum discharge).
There is no need to drain excess supernatant liquid after discharging the scum.

Therefore, according to this invention, although it has a simple configuration as described above, it has the effect that scum generated in a batch type activated sludge treatment tank where the water level fluctuates rapidly can be efficiently discharged and recovered.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an embodiment of this invention, and FIG. 2 is a longitudinal sectional view of the main part. DESCRIPTION OF SYMBOLS 1... Batch type activated sludge treatment tank, 3... Scum discharge device, 8... Scum discharge valve, 9... Scum pit, 11... Scum discharge pipe, 11... Rotating joint, 12... Scum collection pipe, 12a...Scum collection port, 13...Float.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A scum discharge pipe that is installed in a treatment tank that has a scum pit and repeats the batch activated sludge treatment process, and that communicates with the scum pit, and a rotating joint connected to this scum discharge pipe. A scum collection pipe is connected to be vertically swingable and housed in the processing tank, and has a scum collection port at its free end. However, near the low water level during the discharge process, it floats on the liquid surface in the treatment tank, and when the liquid surface is floating near this low water level, there is a float that maintains the scum collection port in a submerged open state, and a float that maintains the scum collection port in a submerged open state, and a The valve is installed in the pipe and opens when the water level in the treatment tank reaches a predetermined low level and receives a signal issued to end the discharge process, and closes after a certain period of time has elapsed from the time the valve was opened. A scum discharge device equipped with a scum discharge valve. (2) A decanter is installed in the treatment tank to float on the liquid surface and discharge the supernatant overflow, and as the water level changes in the treatment tank, the decanter follows the liquid level and descends to a predetermined position. The scum discharge device according to claim 1, wherein the scum discharge valve is opened by inputting a signal when the scum discharge valve is opened. (3) Inside the scum pit, there is a scum collection basket that collects the scum discharged from the scum discharge pipe, and a pump that sucks and discharges the supernatant liquid that has fallen into the scum pit from the scum collection basket. A scum discharge device according to claim 1, characterized in that the scum discharge device is provided.