JPH04310291A - Submerged aeration apparatus - Google Patents

Abstract

PURPOSE:To reduce power for circulating a liquid to be treated and to discharge a clean treated liquid from a treatment tank in a submerged aeration apparatus. CONSTITUTION:A head tank 11 is provided to the upper part of an outer cylindrical pipe 1, and an external pressure type separation membrane 12 for filtering a liquid 4 to be treated and the air diffusing pipe 15 positioned under the separation membrane 12 are immersed in the liquid 4 to be treated which as been received in the head tank 11. When air is injected from the air diffusing pipe 15, the level of the liquid 4 to be treated above the separation membrane 12 rises. Therefore, the liquid 4 to be treated overflows the upper end opening edge of an inner cylindrical pipe 2 to flow in the inner cylindrical pipe 2.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of operating a deep aeration system.

0002

2. Description of the Related Art A deep aeration system has been used as one type of activated sludge treatment system. FIG. 2 shows such a conventional deep aeration device. Here, 1 is an outer cylindrical tube with a bottom in the vertical direction, and inside the outer cylindrical tube 2, an inner cylindrical tube 2 with both upper and lower ends open is arranged concentrically, forming a processing tank 3 having a deep well structure. . The inside of the treatment tank 3 is filled with a liquid to be treated 4 made of an activated sludge mixed liquid, and the inside of the inner cylinder part 2 has a downward flow part 5 for the liquid to be treated 4, and also connects the inner cylinder pipe 2 and the outside. An ascending flow section 6 is formed between the cylindrical pipe 1 and the cylindrical pipe 1. 7 is a circulation pump that circulates the liquid to be treated present in the upper part of the outer cylindrical pipe 1;
The circulating fluid can be supplied into the inner cylindrical tube 2 from the upper end opening of the cylindrical tube 2. A blower 8 is capable of blowing air into the liquid to be treated 4 near the water surface of the inner tube 2. In addition, 9 is raw water, which flows from the upper end opening of the inner cylinder pipe 2 to the inner cylinder pipe 2.
is supplied within.

According to such a configuration, when the circulation pump 7 is operated to supply circulating liquid into the inner cylinder pipe 2, the liquid to be treated in the inner cylinder pipe 2 is blown from the blower 8. The air flows down through the downflow section 5 together with the air. Since pressure based on the water depth is applied due to this descent, oxygen in the air is dissolved in the liquid to be treated 4 and consumed by the highly concentrated activated sludge microorganisms. Next, when the liquid to be treated 4 moves to the upward flow section 6, the air bubbles are released again due to the decrease in water pressure as it rises.

In this way, the liquid 4 to be treated is treated with microorganisms while descending and rising in the treatment tank 3 and reaches the top of the upward flow section 6. The remaining liquid is sent to the next step as the processing liquid 10.

[0005]

[Problems to be Solved by the Invention] However, in such a conventional system, it is necessary to operate the pump 7 in order to circulate the liquid 4 to be treated, so there is a problem in that a large amount of power is required for this purpose. . In addition, the treated liquid 10 that has only been treated with the deep aeration device still has a high sludge concentration.
There is also the problem that further treatments such as solid-liquid separation and coagulation and precipitation must be performed in subsequent steps.

The present invention solves these problems by reducing the power required for circulating the liquid to be treated.
Moreover, the purpose is to enable clean processing liquid to be discharged from the processing tank.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a head tank in the upper part of the outer tube, and filters the liquid to be treated in the tank into the liquid to be treated in the head tank. A ceramic external pressure separation membrane and an aeration tube located below the separation membrane are immersed, and the air ejected from the aeration tube raises the level of the liquid to be treated above the separation membrane. The liquid to be treated whose surface has risen is allowed to flow over the upper opening edge of the inner tube and flow down into the inner tube.

[0008]

[Function] With such a system, the liquid to be treated after deep aeration treatment is filtered by the microfiltering action of the separation membrane, and only the filtrate is discharged to the outside of the tank. When operating a separation membrane, it is essential that the liquid to be treated in the tank flow toward the separation membrane using the air lift effect based on the air ejected from the aeration tube. By overflowing the liquid to be treated whose liquid level is raised into the inner cylinder pipe, the liquid to be treated in the tank is circulated. Therefore, there is no need to provide a special pump for circulation, and the power required for this purpose is reduced.

[0009]

[Embodiment] In FIG. 1, a head tank 11 in the form of a part of the outer tube 1 bulged is provided at the upper part of the upward flow section 6 formed between the inner tube 2 and the outer tube 1. It is formed. In the head tank 11, a ceramic external pressure type separation membrane 12, which is constructed by unitizing a large number of tubular filtration membranes, is provided so as to be submerged in the liquid to be treated 4. A conduit 13 to the outside of the tank is connected to the separation membrane 12, and this conduit 13 is provided with a pump 14 for suction. Head tank 11 below the separation membrane 12
A diffuser pipe 15 is provided inside the tank, and a blower 17 for pressure-feeding air to the diffuser pipe 15 is provided in a conduit 16 connected to the diffuser pipe 15 from outside the tank.

The upper opening edge 18 of the inner tube 2 is configured to be located slightly above the level of the liquid to be treated 4, which is controlled to be at a predetermined level. According to such a configuration, the liquid to be treated 4 that has risen in the upward flow chamber 6 enters the head tank 11, but the pump 14
When a negative pressure is applied to the inside of the external pressure type separation membrane 12, the liquid to be treated 4 is filtered, and only the filtrate purified by the microfiltering effect is passed through the pipe 13 to the outside of the tank. It is discharged and then sent to the next process. When the blower 12 is operated when the separation membrane 12 is operated, the air diffuser 1
Air is ejected upward from 5 into the liquid to be treated 4, and due to the air lift effect based on this air, the liquid to be treated 4 is lifted toward the separation membrane 12 and circulated in the head tank 11.

When air is blown out from the aeration pipe 15, the liquid level of the liquid to be treated 4 rises by the volume of this air as shown by the imaginary line in FIG. Opening edge 1
It will be higher than 8. Therefore, the liquid to be treated 4 that has not been filtered by the separation membrane 12 flows over the upper opening edge 18 and enters the inner tube 2, and is fluidized by the liquid to be treated 4 that flows in one after another into the tank. is circulated.

[0012] In this way, the liquid to be treated 4 can be circulated by utilizing the rise in liquid level that inevitably occurs when air is blown out from the aeration pipe 15, without using a particular pump. Therefore, it becomes possible to reduce the power required for circulation. In addition, since air is supplied from the aeration pipe 15 into the liquid to be treated 4, oxygen is well dissolved into the liquid to be treated 4.

[0013]

[Effects of the Invention] As described above, according to the present invention, not only can the power required to circulate the liquid to be treated in the tank be significantly reduced, but also the clean filtration caused by the external pressure type separation membrane can be achieved. Only the liquid can be discharged outside the tank.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a deep aeration device according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a conventional deep aeration device.

[Explanation of symbols]

1 Outer tube 2 Inner tube 4. Liquid to be treated 11 Head tank 12 Separation membrane 15　　　　Air diffuser pipe 18 Top opening edge

Claims (1)

[Claims] 1. A deep aeration device having a deep well structure, comprising a bottomed outer tube and an inner tube opened at both upper and lower ends and disposed inside the outer tube, the upper part of the outer tube being A head tank is provided in the head tank, and a ceramic external pressure type separation membrane is provided in the liquid to be treated in the head tank to filter the liquid to be treated in the tank;
The aeration pipe located below this separation membrane is immersed, and the liquid level of the liquid to be treated above the separation membrane is raised by the air ejected from the aeration pipe, and the liquid to be treated whose liquid level has risen is A deep aeration device characterized in that the flow overflows the upper opening edge of an inner cylindrical pipe and flows down into the inner cylindrical pipe.