JP2000000586A - Aerobic sewage treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To succeed stable treatment operation by preventing the outflow of foam even when the foam is generated by the fluctuations of an operation condition by opening an intake port to the side wall of an aeration tank and connecting a drain equipment equipped with a U-shaped flow channel having an overflow port arranged to the end part on the drain side thereof to the intake port. SOLUTION: An intake port 2 is bored in the side wall of an aeration tank and a drain equipment 3 equipped with a U-shaped flow channel 3a having an overflow port 4 arranged to the end part on the drain side thereof is connected to the intake port 2. When the aeration tank 1 is filled with creamy foam 12 by the fluctuations of an operation condition, inner pressure is allowed to act on the intake port 2 by utilizing the difference between the water level on the side of the intake port 2 and that on the side of the overflow port 4 in the water to be treated sealed in the U-shaped flow channel 3a. By this constitution, the outflow of foam 12 is prevented and stable operation is continued. Even if raw sewage 10 is injected at this time, treated sewage flowing in the drain equipment 3 along with the foam 12 is separated from the foam 12 when passed under the water 14 to be treated to be discharged as water 11 to be treated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for treating high-concentration organic sewage discharged from the livestock industry, food processing industry and the like.

[0002]

2. Description of the Related Art A method using activated sludge has been conventionally used for purification treatment of organic wastewater. This method converts activated sludge, which is a collection of useful microorganisms contributing to the decomposition of organic matter contained in organic wastewater, into an aeration provided with an aeration device for supplying oxygen necessary for the activity of the useful microorganisms in the activated sludge. It is stored in a tank, sewage is added to the aeration tank, and organic substances in the sewage are aerobicly (oxidized) decomposed by useful microorganisms in the activated sludge. The water to be treated is discharged out of the aeration tank by overflow, and the supernatant obtained by settling and separating the activated sludge in the settling tank is discharged to the outside of the system. A part of the activated sludge settled and separated is returned to the aeration tank for the purpose of increasing the sludge concentration in the aeration tank.

[0003] When a relatively high concentration of sewage is subjected to aerobic treatment such as in a night soil treatment plant, bubbles generated by aeration often pose a problem. Generally, the aeration tank is provided with a vent for releasing the aerated air and a drain for the purified water to flow out of the system due to overflow. Spilled foam overflows from vents and drains, causing secondary pollution. Further, when this phenomenon becomes remarkable, most of the treated sewage in the aeration tank overflows out of the tank as bubbles, and a normal treatment operation may not be possible.

Conventionally, foam generated on the water surface of an aeration tank is destroyed by a mechanical defoaming device or a spray defoaming device installed on the water surface, and at the same time, a hanging wall is provided in front of a drain port to prevent foam overflow. Preventing.

[0005]

However, the following problems remain on the hanging wall. In the aerobic sewage treatment apparatus according to the conventional technique shown in FIG. 1, an aeration tank 1 is provided with an aeration blower 6 and a diffuser 7, and the bubbles 12 generated by the aeration are defoamed by the defoaming apparatus 5 to remove the bubbles. Prevents outflow.
At the same time, a hanging wall 8 is provided in front of the overflow port 4 to prevent overflow of bubbles. When the sewage raw water 10 is injected, the water to be treated 11 naturally flows out of the overflow port 4 due to the rise of the water level in the aeration tank.

When bubbles are generated on the water surface of the aeration tank, the water level of the aeration tank has a water level drop 9 corresponding to the generated bubbles. The drop in water level depends on the density of the foam and is greater for creamy dense foam. When treating very high-concentration sewage with an organic matter concentration of several percent, the required amount of aeration increases, especially when the quality of the treated sewage in the aeration tank deteriorates due to any change in operating conditions. This phenomenon became remarkable, and finally, as shown in FIG. 2, the entire aeration tank was filled with cream-like foam having a density close to that of water, and the foam under the hanging wall overflowed and flowed out of the system. Resulting in. If the raw sewage water 10 is further injected in a state where such normal operation is not performed, the quality of the treated sewage 13 is further deteriorated, the generation of bubbles is increased, and finally the operation becomes impossible.

SUMMARY OF THE INVENTION An object of the present invention is to provide a sewage treatment apparatus for treating high-concentration organic sewage, which is capable of preventing the outflow of bubbles even when significant bubbles are generated due to a change in some operation conditions. An object of the present invention is to provide an aerobic sewage treatment apparatus capable of continuing operation.

[0008]

Means for Solving the Problems In order to solve the above-mentioned problems, an aerobic sewage treatment apparatus according to a first aspect of the present invention has an intake port formed in a side wall of an aeration tank and a drain side end portion. A drainage device having a substantially U-shaped flow path having an overflow port is connected to the water intake port. An aerobic sewage treatment apparatus according to a second invention is characterized in that, in the first invention, the position of the overflow port on the drain side is higher than the position of the intake port.

The organic wastewater to be treated according to the present invention includes high-concentration wastewater in which the generation of foam is remarkable and the concentration of organic substances discharged from the livestock industry and the food processing industry reaches several percent. However, the present invention is not limited to this, and can be used for organic wastewater having an organic substance concentration of 1% or less.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. First, in the apparatus of FIG. 3 showing the first embodiment, an intake port 2 is provided on a side wall of a box-type aeration tank 1, and the intake port 2 is provided with an overflow port 4 at a drain side end.
Is connected to a drainage facility 3 having a substantially U-shaped flow path 3a having Overflow port 4 of this drainage system 3
Is located higher than the intake 2. Further, the aeration tank 1 is provided with an aeration blower 6 and a diffuser 7, and bubbles 12 generated by the aeration are defoamed by the defoaming device 5 to prevent the bubbles 12 from flowing out of the tank. The side wall of the aeration tank 1 above the water intake 2 functions as a hanging wall 8 to prevent overflow of bubbles. When the sewage raw water 10 is injected, the water to be treated 11 flows out naturally from the overflow port 4 due to the rise in the water level of the aeration tank.

In the case of treating sewage having a very high concentration of organic matter of several percent, especially when the quality of the treated sewage in the aeration tank deteriorates due to a change in some operating conditions, FIG. As shown in the figure, the entire aeration tank 1 is in a state of being filled with cream-like foam 12 whose density is close to that of water. At this time, since aeration is not performed in the drainage facility 3, the to-be-processed water 14 is present in the U-shaped flow path 3a. Due to the difference in water level between the intake port 2 side and the overflow port 4 side of the enclosed water 14 to be treated, internal pressure is applied to the intake port 2, and bubbles 1
2 can be prevented from flowing out by being sealed with water, and normal operation can be maintained. Further, even when the raw sewage water 10 is injected in this state, the treated sewage that has flowed into the drainage facility 3 with bubbles is separated from the bubbles when passing through the enclosed water 14 to be treated, and overflows. The normal operation is maintained by flowing out of the water 4 as the water 11 to be treated.

At the time of actual implementation, in the drainage facility 3, the height difference between the bottom of the drainage facility 3 and the intake 2 and the intake 2
By appropriately setting the height difference between the sewage and the overflow port 4, an aerobic sewage treatment apparatus suitable for the sewage to be treated can be configured.

FIG. 5 shows a second embodiment of the invention, in which an intake port 2 is provided on the side wall of a vertical cylindrical aeration tank 20, and an overflow port 4 is provided at the intake port 2 at the end on the drain side. Is connected as a drainage facility with a substantially U-shaped pipe 21 having the same structure as that of the first embodiment.

When the garbage wastewater (BOD 40,000 ppm) generated from the garbage disposal plant was treated using this apparatus, a large amount of creamy foam was generated. By setting the height difference L1 between the intake port 2 and the intake port 2 to 40 cm, and the height difference L2 between the intake port 2 and the overflow port 4 to 10 cm, the loss of bubbles was prevented, and a good treatment operation could be performed.

Further, in the apparatus shown in FIG. 6 showing the third embodiment, a large flow area is provided at the bottom of the drainage facility 3 so that the drainage facility 3 also functions as a sludge settling tank 22. Otherwise, the configuration is the same as that of the first embodiment.

When the same raw garbage wastewater as described above was treated using this apparatus, the clogging of the drainage facility 3 by the sludge 23 did not occur, and only the clear supernatant remained in the water 1 to be treated.
It flowed out from the overflow port 4 as 1.

[0017]

According to the aerobic sewage treatment apparatus of the present invention,
By the water sealing action of the to-be-processed water sealed in the drainage equipment having a substantially U-shape, even when the aeration tank is filled with cream-like foam, the foam can be prevented from flowing out, and normal operation can be continued. Become. At the same time, even if the injection of raw sewage is continued in the above operating state, the treated sewage accompanied by bubbles is separated from the bubbles when moving through the water to be treated enclosed in a drainage facility having a substantially U-shape. And flows out of the system, so that normal operation can be continued.

[Brief description of the drawings]

FIG. 1 is a schematic sectional explanatory view of a conventional aerobic sewage treatment apparatus.

FIG. 2 is a schematic sectional explanatory view showing a state of treatment by a conventional aerobic sewage treatment apparatus.

FIG. 3 is a schematic sectional explanatory view showing a first embodiment of the aerobic sewage treatment apparatus of the present invention.

FIG. 4 is a schematic sectional explanatory view showing a treatment state by the aerobic sewage treatment apparatus of the present invention according to the first embodiment.

FIG. 5 is a schematic sectional explanatory view showing a second embodiment of the aerobic sewage treatment apparatus of the present invention.

FIG. 6 is a schematic sectional explanatory view showing a third embodiment of the aerobic sewage treatment apparatus of the present invention.

[Explanation of symbols]

 1: Aeration tank 2: Intake port 3: Drainage facility 3a: Substantially U-shaped channel 4: Overflow port 5: Defoaming device 6: Aeration blower 7: Aeration device 8: Hanging wall 9: Water level drop 10: Sewage raw water 11: Water to be treated 12: Bubbles 13: Treated sewage 14: Enclosed water to be treated 20: Vertical cylindrical aeration tank 21: Substantially U-shaped pipe 22: Sludge settling tank 23: Sludge L1: Substantially U-shaped pipe Height difference between intake L2: Height difference between intake and overflow

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kenji Fukushima 1-6-1 Funakoshi Minami, Aki-ku, Hiroshima-shi, Hiroshima F-term in Japan Steel Works, Ltd. (reference) 4D028 AB03 BC03 BC19

Claims (2)

[Claims] 1. An intake port is formed on the side wall of the aeration tank,
An aerobic sewage treatment apparatus, wherein a drainage facility having a substantially U-shaped flow path having an overflow port at a drainage side end is connected to the water intake port. 2. The aerobic sewage treatment apparatus according to claim 1, wherein the position of the overflow port is higher than the position of the water intake port.