JPS6325834B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention replenishes oxygen and controls the dissolved oxygen concentration in the activated sludge method by testing water by continuous water sampling using an overflow system installed outside the aeration tank. This device relates to an aeration amount adjustment device in the activated sludge method, which aims to control the output of the engine and reduce the amount of electricity or fuel used as a power source to achieve economical operation and save energy. It is.

In the activated sludge method, in order to replenish the oxygen consumed during the biodegradation and biosynthesis processes of organic matter, air is sent into the mixed liquid in the aeration tank to generate fine bubbles and dissolve oxygen into the water. In addition to supplying oxygen to the activated sludge, the entire aeration tank is stirred and mixed to uniformly disperse the activated sludge, thereby achieving contact with organic wastewater. The concentration of oxygen introduced in this way is usually controlled to be 1 to 3 mg/deg/ml. Here, the dissolved oxygen concentration in the aeration tank is 0.5
When the concentration becomes extremely low, such as below mg/mg, the respiration rate of microorganisms is restricted, causing odor to be emitted and the BOD removal rate to decrease. In addition, excessive aeration has a large effect on treatment efficiency, such as by causing activated sludge to float in the settling tank, so the dissolved oxygen concentration in the aeration tank should be adjusted to an appropriate level (1.
Care has been taken to maintain the concentration at ~3mg/).
However, there was no change in the amount or quality of raw wastewater,
In addition, if the activated sludge concentration is adjusted appropriately, this condition can be easily met, but in reality, in cases where there are large fluctuations in water volume and quality between daytime and nighttime, such as in industrial wastewater and sewage, That adjustment is difficult. Therefore, in order to adequately manage activated sludge concentration and return sludge, the aeration rate (oxygen supply) of the aeration tank must be adjusted.
need to be done appropriately. However, in actual operation, unless there is an effect such as the floating of activated sludge due to excessive aeration, there is a strong belief that even if there is excessive aeration, the power cost will be wasted. The amount of air blown is only adjusted when the amount fluctuates significantly. For example, when using either positive displacement or centrifugal type blowers, the only thing you have to do is increase or decrease the number of blowers, open the air release valve to adjust the amount, or operate the valve attached to the diffuser pipe to adjust the air flow rate. There are many. In this type of operation, only rated operation is the normal state, and the air volume is adjusted in a way that does not directly affect the function of the blower, so no consideration is given to saving labor on the power side. There were flaws.

In order to eliminate such conventional drawbacks, the present invention aims to eliminate the problems of the electric motor or liquid fuel engine used as the power source for the blower. Power is proportional to the cube of the number of rotations. Based on these three factors, the air flow rate is adjusted by controlling the rotational speed of the blower, which is the oxygen supply source, according to the operating status of the facility using the activated sludge method, and from the result, the electric power of the electric motor or engine, which is the power source, is adjusted. It also saves fuel consumption as much as possible and increases economic efficiency.

An embodiment of the present invention will be described with reference to the drawings. 1 is a dissolved oxygen measuring device that measures the amount of dissolved oxygen in activated sewage in an aeration tank 5 using a diaphragm electrode method; It is composed of The prime mover 6 is interlocked with a blower 8 via a variable speed device 7, and a blower pipe 9 connected to the blower 8 is inserted into the aeration tank 5, and a large number of holes are provided throughout the bottom of the aeration tank 5. An air diffuser pipe 10 located at is attached to the tip of the air supply pipe. Reference numeral 11 denotes a flow cell installed outside the aeration tank 5, in which the lower part of the detection unit 2 is housed in a reservoir 12 provided on one side of the interior, and a water guide pipe 16 connected to a pump 15 installed inside the aeration tank 5. is connected to the bottom of the reservoir chamber 12. Further, a valve 18 is attached to a branch pipe 17 provided in the water guide pipe 16. Reference numeral 13 denotes a second chamber that accommodates the test water that overflows from the upper part of the reservoir chamber 12;
The chamber 13 and the aeration tank 5 are connected by a pipe 14.

Next, to explain the operation of this embodiment, the driving force of the prime mover 6 rotates the blower 8 via the variable speed device 7, and air is supplied into the aeration tank 5 from the aeration pipe 10 via the air supply pipe 9. to dissolve oxygen in organic wastewater and increase the amount of dissolved oxygen. The organic wastewater in the aeration tank 5 is sent by the pump 15 through the pipe 16 to the bottom of the reservoir chamber 12 in the flow cell 11 as test water, and the test water having a constant flow rate can be continuously sampled by an overflow method. This allows accurate measurements to be taken at all times. A signal obtained by measuring the sample water in the reservoir chamber 12 with the detection section 2 is guided to the conversion section 3, and the signal is sent to the aeration tank 5.
The amount of dissolved oxygen in activated sludge water is indicated. Furthermore, the input to the converter 3 is guided to the transmitter 4,
This signal is transmitted to the variable speed device 7. This variable speed device 7 has a built-in receiving device that selects the signals sent from the transmitter 4, and based on the results of the selection, changes the rotation speed within the variable speed device 7 as needed, and transmits this to the prime mover 6. tell. In the prime mover 6, the rotational speed is increased or decreased according to this speed change signal, and the rotational speed is directly transmitted to the blower 8 via the variable speed device 7, and a predetermined amount of air is sent into the aeration tank 5 through an air supply pipe and an aeration pipe. Air is blown through 10. Since the amount of air blown is proportional to the rotation speed, in order to obtain the amount of air blown that maintains the preset dissolved oxygen concentration (1 to 3 ppm) in the aeration tank 5, the rotation speed is changed by operating the variable speed device 7. By changing the rotation speed and transmitting it to the blower 8, it is possible to obtain an amount of air blown according to the rotation speed.

The dissolved oxygen concentration in activated sludge water varies depending on the amount and concentration of activated sludge water flowing into the aeration tank 5, but especially in the case of factory wastewater or sewage, the concentration of dissolved oxygen in the aeration tank 5 is
The amount of activated sludge water flowing into the interior of the tank is drastically reduced, and
Since the concentration is often low, if the amount of air blown during daytime operation is maintained as it is, it will naturally become excessive. Therefore, if you know the amount and concentration of activated sludge water at night in advance and calculate the amount of air based on this, the variable speed device 7 linked to the dissolved oxygen measuring device 1 can
adjustment becomes easier. Note that the variable speed device 7 is distinguished depending on the model of the prime mover 6. For example, when a variable speed electric motor is used, a variable speed device is incorporated in the motor body, so that the rotation speed is adjusted by having the variable speed device receive a signal transmitted from the transmitter 4 of the dissolved oxygen measuring device. In addition, it is also possible to control the rotation speed by mechanically changing gears, and the gear transmission receives the signal sent from the transmitter 4 of the dissolved oxygen measuring device 1, and increases or decreases the rotation speed to the required value and blows air. You can also do this.

As described above, in the present invention, in a flow cell separate from the aeration tank, the amount of dissolved oxygen in the water sampled using the flow cell method by continuous water sampling from the aeration tank can be accurately measured using the detection unit of the dissolved oxygen measuring device. The signal sent from the transmitter is transmitted to the variable speed device and the rotational speed of the prime mover is immediately controlled, allowing air to be blown at an amount that corresponds to the dissolved oxygen concentration in the aeration tank. Even when activated sludge water decreases rapidly at night, it is possible to reduce the shaft power by appropriate air blowing while maintaining the corresponding dissolved oxygen concentration, and to supply air into the aeration tank. However, since the DO value is measured at a separate location, there are no errors in the measured value, and the aeration tank using the activated sludge method can be easily managed by supplementing oxygen and controlling the dissolved oxygen concentration. In addition, by adjusting the ventilation amount, power consumption can be reduced as much as possible to achieve economical operation and a labor-saving effect.

[Brief explanation of the drawing]

The drawing is a piping diagram showing an embodiment of the present invention. 1 is a dissolved oxygen measuring device, 2 is a detection unit, 3 is a conversion unit, 4 is a transmission unit, 5 is an aeration tank, 6 is a prime mover, 7 is a variable speed device, 8 is a blower, 9 is an air supply pipe, 10 is an aeration pipe , 11 is a flow cell, 15 is a pump, 16
is a water pipe.

Claims (1)

[Claims] 1 The blower 8 is connected to the prime mover 6 via the variable speed device 7.
An aeration pipe 10 connected to the tip of an air supply pipe 9 connected to the blower 8 was installed at the bottom of the aeration tank 5, and a pump 15 was installed inside the aeration tank 5 and a pump 15 was installed outside the aeration tank 5. The detecting section 2 of the dissolved oxygen measuring device 1, which is composed of a detecting section 2, a converting section 3, and a transmitting section 4, is connected to the flow cell 11 by a water guide pipe 16, and the detecting section 2 is installed in the reservoir chamber 12 in the flow cell 11, and the transmitting section 4 is connected to the variable speed device 7, and in the flow cell 11, the detection unit 12 detects the amount of dissolved oxygen in the sample water sampled by an overflow cell method by continuously sampling water from the aeration tank. The activated sludge method is characterized in that the signal sent from the transmitter 3 is transmitted to the transmitter 4, and the variable speed device 7 is controlled by the signal transmitted from the transmitter 4, thereby controlling the amount of air blown by the blower 8. Aeration amount adjustment device.