JPH0688032B2 - Clear water discharge device in wastewater treatment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an apparatus for treating sewage and other wastewater by a batch type activated sludge method, in which after-treatment supernatant water is discharged as floating scum or sludge at the sludge interface. The present invention relates to a supernatant water discharge device in wastewater treatment that reliably discharges the wastewater.

[Conventional technology]

The batch activated sludge method is a method for treating sewage, industrial wastewater, and other wastewater. This is a wastewater supplied into one treatment tank, that is, a certain amount of raw water is allowed to flow in, and after aeration and active treatment by microorganisms, solid substances (mainly sludge) floating in the raw water are precipitated, Next, supernatant water (treated water) and sedimented sludge are separated and discharged individually,
This process of inflowing raw water → aeration → precipitation → discharge (drainage) is repeated. As devices for discharging the supernatant water so as to follow the constantly changing water level, those disclosed in Japanese Utility Model Publication Nos. 60-104204 and 59-7092 are known.

The former is to raise and lower the suction port of the drain pipe with the lifting device installed on the float, and to open and close the space between the float and the suction port to allow the clear water to flow in, and the latter is to feed air to the float tank attached to the drain pipe. It inhales and drains, and raises and lowers the entire drainage pipe above and below the water surface.

[Problems to be Solved by the Invention]

The former may cause sewage and scum to flow from the seal between the suction port and the float, while the latter raises and lowers the entire float by sucking in and out the air from the float tank, which is a major drawback. there were.

An object of the present invention is to provide a supernatant water discharge device in a simple wastewater treatment that can reliably discharge the treated supernatant water without flowing out of floating scum or sludge interface.

[Means for Solving the Problems]

In order to achieve the above object, the present invention is a wastewater provided with a float in a cap box-shaped water collection trough connected to an aerator and a telescopic drainage pipe so as to move up and down in response to fluctuations in water level in a treatment tank. In the supernatant water discharge device for treatment, a water flow guide plate with a size equal to or larger than the outer diameter of the trough is provided at the bottom of the collection trough to guide the inflow of the supernatant water into the trough from the lateral direction. The summary is what you did.

[Work]

Fix the overflow weir of the overflow pipe so that it is at least 5-10 cm above the water surface, cover it with a cap box-shaped water collection trough from above, and dip the outer peripheral plate of the water collection trough to at least 10-15 cm below the water surface. To form a siphon and drain it.

A water flow guide plate having a size equal to or larger than the outer diameter of the trough is provided at the lower part of the collection trough to guide the inflow of the clear water into the trough from the lateral direction.

〔Example〕

 The present invention will be described below with reference to the illustrated embodiments.

In the figure, 1 is a treatment layer for treating wastewater by the batch activated sludge method, and an aeration device 2 which moves up and down in response to fluctuations in water level is provided in the treatment layer 1 having this required volume. This aeration device 2
Is one or more floats 3, which rises and falls in response to fluctuations in water level,
3 and 3 are fixed to the frame 4 of the aerator, and this frame 4
Is provided with an aerator 5 and a cap box-shaped water collecting trough 6 which is located at or near the center of gravity of the entire float,
With the float 3, the entire aeration device 2 is always floated on the water surface even if the water level changes.

Various types of aeration machines 5 are adopted, and the aeration machine 5 is not limited to the illustrated one. The illustrated aerator 5 is a self-priming type, in which a drive shaft 52 is penetrated into a hollow cylindrical cover 51, and a stirring blade 53 outside the cover and always at a predetermined position below the water surface is fixed to the shaft end. Then, a motor 54 is provided on one end of the water surface of this shaft, and when the stirring blade 53 is rotated by this motor to stir the waste water, the negative pressure generated in the stirring liquid is used to drive the inside of the cover or the hollow shape. Air or gas on the water surface is sucked through the shaft 52 and blown into the liquid. The float 3 provided on the frame 4 is not limited to its material, shape, and number of installations, and the aeration device 2 including the aerator 5 is made to stably float above the water surface.

Further, a gantry F is provided on the upper part of the treatment layer 1, and one or a plurality of guide rods G, G are erected between the gantry F and the bottom of the tank, and the guide rod G is part of the frame 4 of the aeration device 2. For example, by inserting and supporting a holder H protruding from the frame 4,
Even if the aeration device 2 moves up and down following the fluctuating water level, it is supported at a predetermined position in the processing tank 1.

The water collecting trough 6 has a cap box shape, and is arranged on the upper part of a flexible tube-shaped drain pipe 7 that can be expanded and contracted, and the lower end of this drain pipe 7 is arranged so that it can be discharged to the outside of the treatment tank 1. It is connected to the fixed drainage pipe 8 provided. A straight tubular overflow pipe 9 integrally provided at the upper end of the telescopic drainage pipe 7 is inserted into the cap box-shaped water collection trough 6, and the overflow weir portion of the overflow pipe 9 is at least 5 on the water surface. It is fixed to the water collection trough 6 via the stay S so as to be about 10 cm, and the water collection trough 6, the liquid flow pipe 9, and the water collection trough 6 and the frame 4 are fixed, respectively. The water collecting trough 6 has a cap box shape with an upside down cup, and the lower end of the outer peripheral plate is fixed so as to be immersed about 10 to 15 cm below the water surface. Over the lower edge, drained into the drainage pipe from the upper end of the overflow pipe that opens in the water collection trough 6 and 5 to 10 cm above the water surface, even if the scum floating on the water surface
It collects water from a depth of 10 cm or less to prevent the scum from getting caught.

Also, the telescopic drainage pipe 7 expands and contracts following the water level fluctuation,
In this case, the guide device 10 is provided so that it can be smoothly and accurately performed.

Further, a water flow guide plate 11 having a size equal to or larger than the outer diameter of the trough is provided in the lower part of the water collecting trough 6 so as to be substantially horizontal and is provided integrally with the outer circumference of the overflow pipe 9 or the drain pipe 7. And At this time, an appropriate gap is provided between the water flow guide plate 11 and the lower edge of the outer peripheral plate of the water collecting trough so that the supernatant water can flow during drainage.

When the supernatant water is drained to the water collection trough 6, a negative pressure is applied to the trough to raise the water level in the trough above the water level in the treatment tank.
A drain control circuit 12 is provided for draining overflow from the overflow pipe 9 by siphoning.

Next, the operation of the device configured as described above will be described.

To treat the wastewater (raw water) that has flowed into the treatment tank by the batch activated sludge method, first operate the aerator 5 and stirrer blades.
The negative pressure generated in the raw water by the rotation of 53 is used to atomize the air, and the air is blown into the water while stirring to achieve the desired aeration.
At this time, the overflow weir of the overflow pipe 9 is set to 5 to 10 cm above the water surface, and the cap trough-shaped water collecting trough 6 is covered from above, so that floating sludge is generated in the aeration process. It can be prevented from flowing into the overflow pipe. That is, it is possible to prevent the sludge from mixing into the treated water.

When the batch activated sludge process has been completed and the sludge has been settled and the supernatant water is drained, if the negative pressure is created by exhausting the water inside the collection trough, the water level in the trough will rise and the overflow will occur. It overflows from the upper end of the pipe and is drained as well as continuously drained by the siphon phenomenon.

In the process of draining the clear water, the aeration device 2 floating on the water surface also follows the drop of the water level with the drainage. Then, even when the sludge interface position is reached and the sludge interface is near the lower part of the water flow guide plate, the water flow guide plate 11 prevents the sludge from being rolled up and entrained during drainage, and only the supernatant water can be drained.

Furthermore, when draining water, even if scum floats on the water surface, the water is collected and drained from a depth of 10 cm or less from the water surface, so the scum will not be involved.

〔The invention's effect〕

According to the present invention, the upper part of the overflow pipe is covered with a cap box-shaped water collecting trough to form a siphon so as to drain water. Therefore, in the aeration process, floating sludge flows into the overflow pipe. There is no fear.

In addition, a water flow guide plate with a size equal to or larger than the outer diameter of the trough is provided at the bottom of the water collection trough to guide the inflow of clear water into the trough from the lateral direction. Even if is near the lower part of the water flow guide, it is possible to prevent the sludge from being rolled up and caught during drainage.

Further, since the outer peripheral plate of the water collecting trough is immersed, even if the scum floats on the water surface, it is possible to prevent the scum from being caught on the water surface.

[Brief description of drawings]

Drawing shows an embodiment of the present invention, Fig. 1 is a vertical sectional front view, Fig. 2 is a vertical sectional side view, Fig. 3 is a plan view, Fig. 4 is an explanatory view of a water collecting trough, and Fig. 5 is the same cross section. It is a side view. 1 is a treatment tank, 2 is an aeration device, 3 is a float, 4 is a frame, 5 is an aerator, 6 is a water collecting trough, 7 is a drain pipe, 11 is a water flow guide plate, and 12 is a drainage control circuit.

Claims (1)

[Claims] 1. A supernatant discharge device for wastewater treatment in a cap water collecting trough provided with a float connected to an aerator and a telescopic drainage pipe so that the float moves up and down in response to fluctuations in water level in the treatment tank. At the bottom of the water collecting trough, a water flow guide plate with a size equal to or larger than the outer diameter of the trough is provided to guide the inflow of clear water into the trough from the lateral direction. Clear water discharge device for wastewater treatment.