JPH0720589B2 - Clear water discharge control device in wastewater treatment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a device for treating sewage and other wastewater by the batch activated sludge method, and ensures that the treated supernatant water is treated by utilizing the siphon phenomenon. The present invention relates to a discharging device.

[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 made to flow in, and after aerating this to perform active treatment with microorganisms, solid matters (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 No. 60-104204 and Japanese Utility Model Publication No. 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 in from the seal between the suction port and the float, while the latter raises and lowers the entire float by sucking air in and out of the float tank over the entire drain pipe. was there.

It is an object of the present invention to provide a supernatant water discharge control device in wastewater treatment that enables reliable drainage of supernatant water using a siphon phenomenon by a simple method.

[Means for Solving the Problems]

An exhaust pipe system for forming a siphon at the time of discharging clear water and a siphon break pipe system are connected to a water collection trough, and the equipment of each pipe system is controlled by a controller. Then, in the exhaust piping system, a water collecting trough and an exhaust unit are connected by an exhaust hose, and an exhaust solenoid valve and a vacuum pump of the exhaust unit are connected to a pressure switch for detecting a negative pressure in the water collecting trough. It is controlled by the controller.

In the siphon break piping system, an intake pipe with a diameter larger than that of the exhaust hose is installed on the float or on the frame, and a solenoid valve that can open the pipe to the atmosphere is installed, and a pressure switch for measuring the pressure in the water collection trough is installed. The pipe to be connected is connected directly from the water collection trough or by branching from the siphon break pipe.

〔Example〕

 Hereinafter, the present invention will be described based on the illustrated embodiments.

In the figure, reference numeral 1 is a treatment tank for treating wastewater by the batch activated sludge method, and an aeration device 2 which moves up and down following the fluctuation of the water level is provided in the treatment tank 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 a frame 4 of an aeration device 2, and an aerator 5 and a cap box-shaped water collecting trough 6 are provided on the frame 4 so as to be at or near the center of gravity of the float. At 3, the entire aeration apparatus 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 of a self-priming type, in which a drive shaft 52 is penetrated into a hollow cylindrical cover 51, and the stirring blade 53 is provided outside the cover and always at a predetermined position below the water surface. It is fixed to the end, a motor 54 is provided on the water surface at one end of this shaft, and the stirring blade 53 is rotated by this motor,
When stirring the waste water, the negative pressure generated in the stirring liquid is used to suck air or gas on the water surface through the inside of the cover or the hollow drive shaft and blow it into the waste water. The float 3 provided on the frame 4 is not limited to its material, shape, and number of installations, and the aerator 2 including the aerator 5 is provided.
What is necessary is that it is stably floating on the surface of the water.

Further, a gantry F is provided on the upper part of the processing tank 1, and one or a plurality of guide rods G, G are installed 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. For example, by inserting and supporting the holder 13 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 a stay so as to be about 10 cm, and the water collection trough 6, the overflow pipe 9, and the water collection trough 6 and the frame 4 are fixed, respectively. The water collecting trough 6 has a shape like an upside down cup, and the lower end of the outer peripheral plate is at least 10 to 15 below the water surface.
It is fixed so as to be immersed in about cm, so that the drainage of the supernatant water overflows the lower edge of the outer peripheral plate of the collection trough 6, and the upper end of the overflow pipe opened in the collection trough and 5 to 10 cm above the water surface. Even if the scum floats to the drainage pipe and floats on the water surface, it collects water from a depth of 10 cm or less from the water surface to prevent the scum from being caught.

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

Further, a water flow guide plate 11 having a size equal to or larger than the outer diameter of the trough is provided under the water collecting trough 6.
Are provided on the outer circumference of the overflow pipe 9 or the drain pipe 7 so as to be substantially horizontal and integrated. 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.

Further, 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 to a level higher than the water level in the treatment tank, and drain water for overflow drainage by the siphon phenomenon from the overflow pipe 9. A control circuit 12 is provided.

As shown in detail in FIG. 1, this drainage control circuit 12 is composed of an exhaust piping system 20 and a siphon break piping system 30. This exhaust piping system 20 is connected to an exhaust hose 21 from a water collection trough 6 An exhaust unit 22 is provided at the tip of the hose 21,
The siphon break piping system is connected to the water collection trough 6 and is provided at the tip end of this intake pipe 31 having a diameter larger than that of the exhaust hose 21 fixed to the frame 4, and the end of this pipe can be opened to the atmosphere. And a solenoid valve 32.

To the exhaust unit 22, a solenoid valve 24 is connected to the end of the exhaust hose 21 via a drain trap 23 or directly, and a vacuum pump is connected to the solenoid valve 24 directly or via an exhaust volume adjusting valve 25 and a flow meter 26. 27 is connected, and another pipe 28 is further connected from the water collection trough 6, a pressure switch 29 is provided at the tip of this pipe 28, and this pressure switch 29, a water level gauge 33 provided in the treatment tank, a solenoid valve 24, The vacuum pump 27 and the control device 40 are electrically connected to each other.

The solenoid valve 32 of the siphon break piping system is also electrically connected to the control device 40. The control device 40 and the motor of the aerator are also electrically connected. And this drainage control circuit 12 is installed all over the water.

The operation of treating the wastewater using the wastewater treatment device configured as described above will be described below.

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 use the negative pressure generated in the raw water by the rotation of the stirring blades 53 to generate air. Is pulverized and stirred while being blown into water to perform desired aeration. At this time, since the overflow weir of the overflow pipe 9 is at least 5 to 10 cm above the water surface and is covered from above by the cap trough-shaped water collection trough 6, sludge floating in the aeration process Can be prevented from flowing into the overflow pipe 9. That is, it is possible to prevent the sludge from mixing into the treated water. In this way, when the batch activated sludge process is completed by aeration for a certain period of time and the sludge content is allowed to settle, and the supernatant water is drained, if the inside of the water collection trough 6 is exhausted to a negative pressure, The water level in the trough rises, overflows from the upper end of the overflow pipe, is drained, and is continuously drained by the siphon phenomenon.

The negative pressure in this trough is performed by suctioning and discharging the air in the water collection trough 6 via the exhaust hose 21 by opening the exhaust electromagnetic valve 24 and starting the vacuum pump 27. When a negative pressure lower than the atmospheric pressure is generated in the water collecting trough, the water position in the trough rises and is overflowed and discharged from the upper end of the overflow pipe 9. In this way, when the vacuum pump is started and a certain time has elapsed, a siphon is formed, but by detecting this with the pressure switch 29, the exhaust electromagnetic valve 24 is closed and the vacuum pump 27 is also stopped. However, since the siphon is formed at this time, drainage is continuously performed.

The set pressure h (mmAq) of the pressure switch 29 is the drainage pipe 7
Inner diameter D (m) and the distance H (m) from the water level in the treatment tank to the top of the water seal part, However, ho: Overflow height (m in relation to the water level in the treatment tank of the overflow weir
It is desirable to set so that m). This prevents the pressure setting value from becoming too high, so the exhaust unit 22
It is possible to operate the vacuum pump 27 for a minimum required time without sucking water, and it is possible to save energy.

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 11, 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,
Since the water is collected and drained from a water depth of 10 cm or less, scum will not be involved.

Then, the water level drops due to drainage, and the low water level LW
When reaching L, the solenoid valve 32 for siphon break is opened by the operation of the water level gauge 33. If the solenoid valve 32 is opened for a predetermined time, the siphon breaks and drainage is stopped.

〔The invention's effect〕

Since the present invention is configured as described above, it has the following effects.

Since an exhaust pipe system and a siphon break pipe are provided in the water collection trough and selectively controlled, the supernatant water can be drained by forming a siphon.

Since the exhaust hose is provided separately from the siphon break pipe, the installation location can be freely selected.

Since the siphon break piping system has a large diameter and is installed in the frame of the aeration device, the siphon can be broken in a short time.

Since the pipe connected to the pressure switch is directly connected from the water collection trough, the pressure switch operates normally without being affected by the pulsation of the vacuum pump and without malfunction.

[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, 12 is a drainage control circuit, and 20 is an exhaust pipe. System, 21 is an exhaust hose, 22 is an exhaust unit, 24 is a solenoid valve, 27 is a vacuum pump, 30 is a siphon break piping system, 31 is an intake pipe, 32 is a solenoid valve, 29 is a pressure switch, and 40 is a control device.

Claims (4)

[Claims] 1. An aerator and an overflow pipe at the upper end of a telescopic drainage pipe are provided on a frame with a float so as to move up and down in response to fluctuations in the water level in the treatment tank, and a cap box-shaped cover is provided so as to cover the aeration machine. In a supernatant water discharge control device for wastewater treatment provided with a water collecting trough, an exhaust pipe system for forming a siphon at the time of discharging the supernatant water and a siphon break pipe system are connected to the water collecting trough, and equipment of each pipe system. And a control device for controlling the discharge of supernatant water in wastewater treatment. 2. The exhaust pipe system is connected between the water collection trough and the exhaust unit with an exhaust hose, and the exhaust solenoid valve / vacuum pump of the exhaust unit is used as a pressure switch for detecting negative pressure in the water collection trough. The supernatant water discharger in wastewater treatment according to claim 1, wherein the controller is controlled by a connected controller. 3. The siphon break piping system is characterized in that an intake pipe having a diameter larger than that of an exhaust hose is installed on a float or a frame, and a solenoid valve capable of opening the pipe to the atmosphere is provided. Control device for clear water discharge in wastewater treatment in Japan. 4. The wastewater according to claim 2, wherein the pipe connected to the pressure switch for measuring the pressure in the water collection trough is connected directly from the water collection trough or branched from the siphon break pipe. Clear water discharge control device in treatment.