JPH0673678B2 - Biological treatment tank - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biological treatment tank used for treating organic wastewater such as sewage.

[0002]

2. Description of the Related Art A so-called activated sludge method is known as a method for separating and removing pollutant components in sewage and converting the sewage into a clear and safe one. This is to mix sewage flowing into an aeration tank (aeration tank) with activated sludge composed mainly of microorganisms, and inject compressed air as bubbles from the bottom. In this way, the sewage and the activated sludge are mixed and stirred, and the activity of aerobic microorganisms in the activated sludge is increased by oxygen in the air.
Aggregates, adsorbs and oxidizes soluble microorganisms.

As an aeration tank used for such purposes,
For example, an aeration tank schematically shown in FIG. 3 is known. That is, for example, a substantially cylindrical partition wall 22 is provided in the tank 21, and the partition wall 22 divides the tank 21 into a biological treatment section 10, a sludge settling section 13, and a treated water rising path 15.
Then, wastewater such as sewage is introduced into the biological treatment unit 10 as indicated by arrow A, the wastewater is mixed with activated sludge, and air is supplied from the air diffuser 8 installed at the bottom of the biological treatment unit 10. . The wastewater after the biological treatment is sent to the sludge settling section 13, where the sludge in the wastewater is deposited, and the treated water separated from the sludge rises up the treated water ascending path 15 as indicated by arrow G.
After this, the treated water that has reached the water level 7 is treated water receiving portion 21a.
And is discharged to the outside of the device as indicated by an arrow H. From the bottom of the tank 21, the sludge is removed at any time as indicated by arrow F.
In the figure, 6 is a sludge scraper.

[0004]

However, in the apparatus as shown in FIG. 2, the sludge in the sludge settling section 13 may be wound up to the biological treatment section 10, which lowers the sludge settling efficiency.
Further, it is necessary to return the activated sludge to the biological treatment section 10.

The object of the present invention is to prevent the sludge accumulated in the sludge settling section from being rolled up to improve the sludge settling efficiency, and also to make the activated sludge return to the biological treatment tank unnecessary or insignificant. It is to provide such a wastewater treatment device.

[0006]

The present invention relates to a biological treatment section for mixing activated sludge containing aerobic microorganisms with wastewater flowing into the biological treatment section to biologically treat organic matter in the wastewater; An air diffuser disposed in the biological treatment section for blowing air into the biological treatment section; a wastewater ascending path divided by the first partition wall with respect to the biological treatment section to raise the wastewater after the biological treatment. A wastewater ascending path for causing the wastewater ascending path; a wastewater descending path divided by the second partition wall with respect to the wastewater ascending path, and a wastewater descending path for descending the wastewater rising to the upper end of the wastewater ascending path; A sludge sedimentation part formed below the biological treatment part, which is separated from the biological treatment part by a third partition wall and communicates with the lower end of the wastewater descending path; and the sludge sedimentation part Treated water after passing A process-water riser passage for raising the, having the biological treatment process water riser passage that is separated by a fourth partition wall with respect to unit, but according to the biological treatment tank.

[0007]

EXAMPLE FIG. 1 is a schematic view showing a biological treatment tank according to an example of the present invention. Hereinafter, this apparatus will be described mainly according to the flow of wastewater.

The inside of the tank 1 is generally a biological treatment section.
It is divided into 10, a wastewater rising path 11, a wastewater descending path 12, a sludge settling section 13 and a treated water rising path 15. First, a biological treatment unit 10 having, for example, a cylindrical shape is provided on the upper side of the tank 1, and waste water is injected into the biological treatment unit 10 as indicated by an arrow A. In the biological treatment unit 10, activated sludge containing aerobic microorganisms is mixed with wastewater, and organic matter in the wastewater is biologically treated. At the bottom of the biological treatment unit 10, an air diffuser 8 for blowing air into wastewater is installed.

The wastewater flowing in the biological treatment section 10 as shown by the arrow B then rises in the wastewater rising path 11. This wastewater ascending path 11 is provided inside the biological treatment section 10 and is divided by this and the first partition wall 4.

Next, when the wastewater that has risen in the wastewater rise passage 11 reaches the upper end of the wastewater rise passage 11, it overflows the second partition wall 5 as shown by arrow C and descends in the wastewater fall passage 12. The wastewater ascending path 11 and the wastewater descending path 12 are divided by the second partition wall 5.

A sludge settling section 13 is formed below the biological treatment section 10, the wastewater rising path 11 and the wastewater descending path 12. Then, the biological treatment unit 10, the wastewater rising path 11, and the sludge settling unit 13 are isolated from each other by the third partition wall 9, and direct circulation of the wastewater is blocked. Further, the lower end of the wastewater descending path 12 communicates with the sludge settling section 13, and the wastewater flowing down the wastewater descending section 12 flows into the sludge settling section 13. Further, an extension portion 5a is formed at the lower end of the second partition wall 5 beyond the third partition wall 9.

A sludge scraper 6 is installed in the sludge settling section 13, and sludge is removed from the bottom of the tank 1 at any time as indicated by arrow F.

A treated water rising path 15 is provided outside the biological treatment section 10 with a fourth partition wall 2 interposed therebetween.
The lower end of 15 communicates with the outer periphery of the sludge settling section 13. Therefore, the wastewater flowing down in the wastewater descending path 12 passes through the sludge settling section 13 as shown by an arrow D, and the treated water separated from the sludge finally rises in the treated water ascending path 15, As shown by E, the overflowed water enters the treated water receiving portion 1a, from which it is discharged as shown by arrow H, for example, discharged.

A skirt 2a is formed at the lower end of the fourth partition 2 and extends further downward from the position where the third partition 9 is joined. The third partition wall 9 is provided with one or more gas vents 3 with check valves. In addition, 7 in the figure is a water level surface.

According to the biological treatment tank of this embodiment, the biological treatment section 10 and the sludge settling section 13 are separated by the third partition wall 9, whereby direct exchange of wastewater between them is blocked. Since the sludge settled in the sludge settling section 13 is not rolled up to the biological treatment section 10, the sludge settling efficiency can be improved.

Further, the first partition wall 4 is provided so that the wastewater rising path 11
And forming a wastewater descending path 12 to raise the wastewater after biological treatment,
Since it is lowered and sent to the pollutant sedimentation tank, wastewater can be treated even if sludge return to the biological treatment section 10 is abolished, or even if this return amount is very small.

Further, since the skirt 2a is provided at the lower end of the fourth partition wall 2, various gases such as sludge decay gas gather in the upper space 20 of the sludge settling section 13. Therefore, the gas collected in the upper space 20 can be effectively discharged from the sludge settling section 13 by removing the gas from the degasser 3 with a check valve, so that the sludge floats up into the treated water rising path 15. You can prevent the coming situation.

Moreover, since the extending portion 5a is provided at the lower end of the second partition wall 5, as compared with the case where this extending portion 5a is not provided,
Since the wastewater can be sent to a deeper region of the sludge settling section 13, the water contained in the wastewater passes through the sludge to the lower end of the treated water ascending path 15, that is, the filtration distance is long, Therefore, separation of treated water from sludge can be further promoted. For the same reason, the filtration distance can be increased to some extent even if the entire tank 1 is downsized.

From the above results, it is possible to obtain treated water that is cleaner than the conventional one, and to improve the treatment efficiency as compared with the conventional treatment equipment, thereby reducing the installation area of the wastewater treatment equipment. It is also possible.

Hereinafter, wastewater treatment experiments were conducted using the wastewater treatment devices shown in FIGS. 1 and 2, respectively. Raw wastewater properties
The BOD was 100 to 150 mg / l and the SS was 150 to 200 mg / l. This raw wastewater was supplied to the wastewater treatment apparatus of the same scale shown in FIGS. 1 and 2 and operated. As a result, the properties of the treated water were as follows.

[0021]

According to the biological treatment tank of the present invention, the biological treatment section and the sludge settling section are separated by the third partition wall,
As a result, direct interaction between the wastewater is prevented between the two, so that sludge accumulated in the sludge settling section is not rolled up to the biological treatment section, and therefore the pollution settling efficiency can be improved.

Further, a wastewater rising path separated from the biological treatment section by the first partition is provided, the wastewater after the biological treatment is raised in this wastewater rising path, and then the wastewater rising to the upper end of the wastewater rising path is discharged. Since it is lowered and sent to the sludge settling section, the biological treatment of wastewater can be carried out even if sludge return to the biological treatment section is abolished or even if the returned amount is very small.

[Brief description of drawings]

FIG. 1 is a schematic view showing a biological treatment tank according to an embodiment of the present invention.

FIG. 2 is a schematic view showing a biological treatment tank according to a conventional example.

[Explanation of symbols]

 1,21 Tanks 1a, 21a Treated water receiving part 2 Fourth partition 2a Skirt extending to the lower end of the fourth partition 3 Gas vent with check valve 4 First partition 5 Second partition 5a Second partition Extension part at the lower end of the tank 6 Sludge attractor 7 Water level 8 Air diffuser 9 Third partition wall separating the biological treatment section and the sludge sedimentation section 10 Biological treatment section 11 Wastewater ascending path 12 Wastewater descending path 13 Sludge sedimentation section 15 Treated water rising path 20 Upper space of sludge settling area A, B, C, D Wastewater flow E, G, H Flow of treated water separated from sludge F F Sludge removal

Claims (1)

[Claims] 1. A biological treatment unit for mixing activated sludge containing aerobic microorganisms with wastewater flowing into the biological treatment unit and biologically treating organic matter in the wastewater; for blowing air into the wastewater, An air diffuser disposed in the biological treatment section; a wastewater rising path divided by the first partition wall with respect to the biological processing section, for raising the wastewater after the biological processing; A wastewater descending passage divided by a second partition wall with respect to the wastewater rising passage, the wastewater descending passage for descending the wastewater rising to the upper end of the wastewater rising passage; formed below the biological treatment section A sludge sedimentation part, which is isolated from the biological treatment part by a third partition wall and communicates with the lower end of the wastewater descending path; and the treated water after passing through the sludge sedimentation part is raised. Increased treated water to allow A biological treatment tank having a treated water rising passage isolated from the biological treatment section by a fourth partition.