JP2833888B2 - Operating method of aeration device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention efficiently controls nitrification and denitrification of sewage by controlling the operation of a plurality of aerators individually to form aerobic and anaerobic conditions in an endless waterway. The present invention relates to a method of operating an aeration apparatus.

[0002]

2. Description of the Related Art In the treatment of sewage containing organic substances such as domestic sewage and industrial waste sewage, an aeration tank having a circulating water channel, that is, a so-called non-terminal water channel, such as a double circular water channel such as an ellipse or a circle. One or more aeration devices are installed, air is forcibly supplied to the sewage in the tank, oxygen in the air is dissolved in the sewage, and the sewage is mixed with the air and stirred to aerate. That is, a method of performing an aerobic fermentation treatment has been proposed. The aeration decomposes organic matter to purify sewage.

[0003]

Therefore, even if organic matter in sewage can be treated by aerobic fermentation, not only oxygen is always supplied but also nitrogen is removed in sewage to remove nitrogen, that is, denitrify. It is also necessary to be in an anaerobic state. In order to form aeration in the same aeration tank, that is, to form an aerobic state and an anaerobic state, it is necessary to control the operation of the aerator in the tank. For this reason, a ventilation valve is provided in one aerator, and aerobic and anaerobic operation is enabled by opening and closing this valve. However, in this aerobic / anaerobic combined machine, the operation of the aerator is stopped when switching from the aerobic operation to the anaerobic operation, so that the agitation of the sewage is stopped and the sludge settles. When the sludge settles at the bottom of the tank, the efficiency of the nitrifying liquid, the carbon source in the influent and the activated sludge cannot be brought into contact, and sufficient denitrification cannot be performed. When switching between aerobic and anaerobic by opening and closing the ventilation valve in the aerobic / anaerobic combined machine, it is merely an opening and closing operation of the valve. Therefore, compared to the aerobic operation, the sewage does not need to be strongly agitated during the anaerobic operation, but a single aerator performs the anaerobic operation with the same agitation power in accordance with the aerobic operation. It will be great.

[0004] It is an object of the present invention to adjust the agitation power for aerobic / anaerobic operation and to operate with an agitation power optimal for each operation situation.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and has an aerator capable of switching between aerobic operation and anaerobic operation, and an aerobic exclusive aerator for performing only aerobic operation. In addition to installing in the aeration tank in combination with aerobic operation, aerobic operation of both aerators during aerobic operation, anaerobic operation of switchable aerators during anaerobic operation, and stopping other aerobic dedicated aerators The point is that denitrification is promoted.

[0006]

[Function] A single aeration tank is provided with an aerator dedicated to aerobic and an aerator capable of switching between aerobic and anaerobic. During the aerobic operation, both aerators are aerobically operated, and during the anaerobic operation, the switchable aerator is set as the anaerobic operation, and the other aerobic-dedicated aerators are stopped. This allows the required flow velocity to be obtained at the bottom of the tank with minimum power even during anaerobic operation, preventing sludge from settling,
The efficiency of the nitrification liquid, the carbon source in the influent water, and the activated sludge can be brought into contact, so that efficient and stable denitrification can be performed.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the operation of an aeration apparatus according to the present invention. In the drawing, reference numeral 1 denotes an aeration tank having a circular or oval endless channel formed as shown in the figure.
For example, an aerator 3 for both aerobic and anaerobic operation is provided on the inner peripheral side of the water channel on a radial line passing through the center of the circular aeration tank 1 and parallel to the water channel direction, and an aerial device 2 for aerobic only is provided on the outer peripheral side. Is arranged.

When the two aerators 2 and 3 are arranged as a set as described above, if the two aerators 2 and 3 are simultaneously operated or stopped and operated at the same time, the dissolved oxygen (FIG. 2) shown in FIG. DO). When one of the two aerators 2 and 3 is continuously operated and the other is repeatedly operated and stopped, a DO change as shown in FIG. 3 is exhibited. However, during the anaerobic operation, when the aerobic dedicated machine 2 is stopped and the ventilation valve of the combined use machine 3 is closed to operate, a DO change as shown in FIG. 4 is obtained.

FIG. 5 is a graph showing the aerobic time ratio and the TN removal rate when the two aerators 2 and 3 are operated in this manner. Accordingly, the denitrification rate becomes 1.2 to 1.5 times and the denitrification rate becomes 80% or more as compared with the conventional operation method.

When the aerobic / anaerobic type aerator 3 is installed on the inner peripheral side of the endless water channel, the sewage on the inner peripheral side of the water channel is constantly stirred regardless of whether the inside of the tank is operated aerobically or anaerobically. Therefore, there is an advantage that a predetermined flow rate can always be secured on the inner peripheral side, and sludge sedimentation can be prevented. However, in the case of an elliptical channel or the like, it may be installed on any side, and in the case of a circular channel, a combined type may be installed on the outer peripheral side depending on the type of sewage.

[0011]

According to the method of operating the aeration apparatus of the present invention, a combination of an aerator capable of switching between aerobic operation and anaerobic operation and an aerator dedicated to aerobic operation is provided in an aeration tank. During aerobic operation, both aerators are operated aerobically, during anaerobic operation, switchable aerators are set to anaerobic operation, and other aerobic-only aerators are stopped. This has the advantage that denitrification can be performed stably and efficiently without performing.

[Brief description of the drawings]

FIG. 1 is a plan view of one embodiment for explaining a method of operating an aeration apparatus of the present invention.

FIG. 2 is a graph showing a change in DO when two aerators are simultaneously operated or stopped.

FIG. 3 is a graph showing DO changes when one of two aerators is operated continuously and the other is operated intermittently.

FIG. 4 is a graph showing a DO change according to a method of operating the aeration apparatus of the present invention.

FIG. 5 is a graph showing a TN removal rate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Aeration tank 2 Aerobic / anaerobic combined type aerator 3 Aerobic exclusive type aerator

Claims (1)

(57) [Claims] An aerator capable of switching between aerobic operation and anaerobic operation and an aerobic exclusive aerator for performing only aerobic operation are provided in an aeration tank in combination, and both aerators are used during aerobic operation. Operation of an aeration apparatus characterized in that aerobic operation is performed, and an aerator that can be switched during an anaerobic operation is set as an anaerobic operation, and denitrification is promoted by stopping other aerobic-dedicated aerators. Method.