JPH0716564B2 - Clear water drainage device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a supernatant water discharge device for discharging supernatant water after aeration of waste water in a batch type activated sludge treatment tank.

[0002]

2. Description of the Related Art Conventionally, as a drainage device for discharging the supernatant water of a batch type activated sludge treatment tank, there is a practical use as a drainage device.
Those disclosed in Japanese Patent Laid-Open No. 04, 59-7092 and the like are known. The former is to raise and lower the suction port of the water distribution pipe with the lifting device installed on the float to open and close the space between the float and the suction port to let in clear water, and the latter sucks air into the float tank attached to the drain pipe. , Discharges and raises and lowers the entire drainage pipe above and below the water surface.

[0003]

The former may cause sewage and scum to leak from the seal portion between the suction port and the float, and the latter moves up and down the entire drain pipe by the air suction and discharge of the float tank, which is a large device. There was a drawback that became. An object of the present invention is to provide a supernatant water drainage device capable of stably discharging supernatant water with a simple mechanism.

[0004]

In order to achieve the above object, in the supernatant water drainage device of the present invention, a bottomed water collecting container having a water collecting port opening at a position below the water surface is fixed to a float. The summary is that an overflow weir that is connected to the drainage pipe via an expansion tube is installed inside the water collection container, and an elevating device that elevates the overflow weir from a position below the water surface to a position above the water surface is provided. , As a result, during aeration, the overflow weir is lifted above the water surface by the lifting device so that sewage is not discharged, and when the supernatant water is drained, the overflow weir is lowered and flows in from the water collecting port that opens below the water surface. By discharging only the supernatant water that does not contain scum, stable water quality is maintained.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The clear water drainage device of the present invention will be described below with reference to the illustrated embodiments. As shown in the figure, the supernatant water drainage device of the present invention has two floats 1 on both sides and is used by floating on the water surface of a batch type activated sludge treatment tank. A water collecting container 2 attached to a lower portion of a connecting member 9 which also serves as a pedestal for connecting the floats 1 on both sides is provided with a water collecting port 3 for taking the supernatant water into the container from the side.

The position where the water collecting port 3 is provided is at least 10 cm below the water surface. This is to prevent the scum floating on the water surface from being sucked together with the clear water. However, if the water collection port 3 is provided too deeply, the water level will drop with the drainage, and when it approaches the sludge interface, the sludge that has settled due to the flow accompanying the water collection will be rolled up and the sludge will be removed together with the supernatant water. 2 below the surface of the water as it may be inhaled
A position of about 0 cm is suitable. Further, the bottom portion of the water collection container 2 is provided with an inclination in order to prevent the scum from adhering to the bottom surface when it floats. Moreover, it is desirable to provide a necessary minimum opening near the lowermost part of this tendency portion so that the sludge accumulated inside the water collection container 2 can be discharged to the outside of the container.

Inside the water collection container 2, a bellows type or telescopic type expansion pipe 5 is attached to a joint 6 fixed to the bottom of the water collection container 2, and an overflow weir 4 is provided above the expansion pipe 5. Set up. The overflow weir 4 is a lifting device 7 attached to the connecting member 9 on the float 1.
It is connected to the operating rod 8 of the above, and the position of the overflow weir 4 can be moved up and down from the position below the water surface to the position above the water surface by the vertical movement of the operating rod 8.

Further, in order to make the float 1 follow the fluctuation of the water level, an arm 11 is attached to the upper part of the connecting member 9, the other end side is fixed to the fixed side, and it swings in an arc around the fixed point. And Therefore, the water distribution pipe 12 from the water collection container 2 is of a telescopic type, but a rotary joint is provided at the bottom of the water collection container 2 as shown in FIG. Drainage may be performed through a straight pipe and a rotary joint at the other end. In that case, since the rotary joint provided deep in the water swings as the fixed point, the arm 11 is unnecessary. In addition, it is possible to use a method of providing a guide column on the side surface of the float 1 and moving the guide column in the vertical direction with respect to such an arc-shaped movement.

Next, the operation of the present invention will be described. The batch type activated sludge treatment tank is provided with an aeration device in addition to the supernatant water drainage device of the present invention, and is configured to perform a cycle operation including a wastewater inflow process and an aeration process, a precipitation process and a drainage process. In the aeration process, the sludge that had settled until then is rolled up, and the entire tank is in a completely mixed state. Therefore, as shown in Fig. 1, if the overflow weir 4 is below the water surface, the sludge gradually overflows. Telescopic drainage pipe 1 for drainage that flows in from the weir 4.
In the time period other than the drainage process, the operating rod 8 is lifted by the lifting device 7 and the overflow weir 4 is accumulated.
The sludge is prevented from entering by raising it above the surface of the water. At this time, the lifting device 7 is connected to the overflow weir 4 and the expansion pipe 5
It does not require a large force to lift only the drainage device, and the lifting device 7 having a smaller capacity than that of the conventional method of lifting the entire drainage device can be used.

After sludge is settled in the settling step using the aeration step, in the draining step, the operating rod 8 is lowered by the elevating device 7, the overflow weir 4 is submerged below the water surface, and drainage is started. Since the overflow weir 4 itself has a valve function in this way, it is not necessary to provide a separate valve in the water distribution pipe 12. Further, since the immersion depth of the overflow weir 4 can be adjusted depending on the ascending / descending state of the operating rod 8, the flow rate of drainage can be adjusted. The clear water is taken in from the water collecting port 3 provided on the side surface of the water collecting container 2. Since the water collecting port 3 is provided at the position below the water surface, the scum should be sucked together even if there is scum on the water surface. There is no.

[0011]

According to the present invention, at the time of aeration, the overflow weir is lifted above the water surface by the elevating device so that the sewage is not discharged, and when the supernatant water is drained, the overflow weir is lowered to the position below the water surface. Stable water quality can be maintained by an extremely simple mechanism by discharging only the supernatant water that does not contain scum that flows in through the open water collection port.
Further, according to the present invention, a bottomed water collecting container having a water collecting port opening at a position below the water surface is fixed to the float, and the overflow weir is connected to the drain pipe through the expansion pipe inside the water collecting container. The scum that floats on the water surface during the precipitation step is not taken into the water collection container during the settling process, and the clear water at the optimum position below the water surface can be taken in during the draining process. Only the supernatant water without scum can be stably discharged.

[Brief description of drawings]

FIG. 1 is a front view of a clear water drainage device of the present invention.

FIG. 2 is a cross-sectional view taken along the line A-A ′ of FIG.

FIG. 3 is a conventional device.

[Explanation of Codes] 1 Float 2 Water collecting container 3 Water collecting port 4 Overflow weir 5 Expansion pipe 6 Joint 7 Lifting device 8 Actuating rod 9 Connecting material 11 Arm 12 Drain pipe

Claims (1)

[Claims] 1. A bottomed water collecting container (2) having a water collecting port (3) opening at a position below the water surface is fixed to a float (1), and a telescopic tube (2) is provided inside the water collecting container (2). An overflow device (8) for arranging an overflow weir (4) connected to the drainage pipe (12) via 5) and moving the overflow weir (4) from a position below the water surface to a position above the water surface is provided. A clear water drainage device characterized by being provided.