JP2564228B2 - Biological sewage treatment equipment - 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 sewage treatment apparatus for treating organic substances such as sewage and industrial wastewater.

[0002]

2. Description of the Related Art A high-speed aeration settling basin is used to separate the aeration process and the final settling process in the activated sludge process, which were conventionally carried out using separate water tanks, into a single partition partitioned by concrete or steel plate partitions. By executing in the water tank, the return sludge process can be omitted, the electric power cost required for the treatment can be reduced, and the amount of organic suspended matter in the aeration section (Mixed Liquid Volatile)
By maintaining Suspended Solids (hereinafter referred to as MLVSS)) at a high concentration of 2,500 to 5,000 mg / l, the wastewater treatment capacity is improved, and aeration which was conventionally required to take 6 to 8 hours is about 2 It is a device that can reduce the installation area of wastewater treatment equipment by performing the treatment within 3 hours.

A stirrer is installed in the aeration section of this high-speed aeration settling basin to assist in the atomization of the inflowing air and complete mixing.

Japanese Patent Application No. 63-33636 discloses the addition of an immobilized carrier for the purpose of improving the quality of treated water in this high-speed aeration sedimentation basin, stabilizing the treatment, and maintaining a high concentration of MLVSS.
And Japanese Patent Laid-Open No. 3-178395. However, since the immobilized carrier is added, the agitator installed in the conventional high-speed aeration sedimentation tank cannot fulfill the function of the apparatus and the processing target. That is, it is impossible to achieve finer inflow air, complete mixing in the aeration section, and floating of the carrier.

[0005]

The conventional stirrer installed in a high-speed aeration sedimentation basin aims at making the inflowing air finer and completely mixing it, and does not particularly consider the floating of the carrier. That is, a carrier having a low stirring strength and a large specific gravity cannot be floated and is deposited on the bottom. Further, even if the rotation speed is simply increased, the carrier is separated from the activated sludge flocs, which does not lead to improvement of treated water quality and stabilization of treatment.

Therefore, the present invention provides a rational apparatus capable of achieving fine atomization of inflowing air, complete mixing, and floating of a carrier in a high-speed aeration sedimentation tank to which an immobilized carrier is added.

[0007]

The gist of the present invention is as follows.

[0008] A creature characterized by having a lower part of a stirrer installed in the aeration part of a high-speed aeration sedimentation basin using an immobilized carrier as a turbine blade and an upper part as a propeller or paddle blade, and arranging a fine bubble diffusing pipe at the bottom of the aeration part. Sewage treatment equipment.

[0009] The biological sewage treatment apparatus as described above, wherein the immobilization carrier is ground granulated blast furnace slag powder.

The biological sewage treatment apparatus as described above, wherein a backflow prevention mechanism is provided in the fine bubble diffusing tube.

[0011]

The present invention will be described in detail below.

FIG. 1 is a longitudinal cross-sectional view to clarify the internal mechanism of the device of the present invention. The water tank body 1 is divided into an aeration section 5, a circulation section 9 and a sedimentation section 10 by an inner cylinder 4 and an outer cylinder 8. The above-mentioned immobilization carrier is added to the aeration section 5 surrounded by the inner cylinder 4 and the water tank body 1. The solidified carrier may be any of zeolite, silica sand, activated carbon, etc., but granulated blast furnace slag is most preferable.

The inflow water W flows from the inflow port 2 near the bottom of the water tank body 1 into the aeration section 5 and is ejected from the air diffuser 3 as air A.
It is circulated in the aeration part 5 by O and the stirrer 12,
Biological treatment is applied. Temporary treated water W ₁ overflowing from the upper part of the inner cylinder 4 and activated sludge 6 adhering and developing around the immobilization carrier
Flows down the circulating portion 9 surrounded by the inner cylinder 4 and the outer cylinder 8. In this process, biological treatment proceeds further, and sludge having a relatively large specific gravity is settled and separated.

The secondary treated water W ₂ overflowing from the lower portion of the outer cylinder 8 to the outside through the circulation portion 9 flows upward in the sedimentation portion 10. Here, activated sludge is settled and separated according to the same principle as a general upward flow type sedimentation basin, but since it contains an immobilized carrier, it has a larger specific gravity than the conventional activated sludge, and the flow inside the aeration section 5 is large. The activated sludge is not mixed in the treated water due to the flow in the precipitation section 10 caused by the above. The supernatant water W ₃ is discharged from the outflow groove 11.

The separated sludge containing the immobilized carrier separated from the treated water in the circulation part 9 and the sedimentation part 10 falls between the inner cylinder 4 and the outer cylinder 8 and the water tank body 1 by its own weight, and again in the aeration part 5. Return to. Excess sludge D ₁ is discharged from the sludge discharge port 7 and separately processed.

The above points are the same as the conventional high-speed aeration sedimentation basin. The points devised in the present invention are as follows.
It is a point.

First, the first point is that the air diffusing device 3 uses a fine bubble diffusing tube. Conventionally, the air diffuser method or only the pipe is installed, and the rotation of the stirrer 12 is used to miniaturize the bubbles. However, as described later, by giving the stirring blade a floating function of the carrier, the aeration device was given the function of making the bubbles fine. The fine bubble diffusing tube may be of any type such as ceramics or diaphragm, but when a fine carrier is used, it is preferable to have a backflow preventing mechanism.

The second point is that the lower stirring blade is provided with a turbine blade capable of floating the carrier and laterally stirring the air. The turbine blade is preferably of a type that creates a flow from the lower part to the upper part so as not to impede the flow of sludge drawn from the end of the inner cylinder skirt. In addition, the rotation of the turbine blade does not cause disassembly of the activated sludge and separation of the carrier,
It is necessary to determine the shape and speed of the turbine blade.

The third point is that a propeller or paddle blade for uniformizing the upward flow is installed above the stirrer. That is, there is a possibility that the circulating flow originating from the inner cylinder may become non-uniform due to the upstream and downstream created by the rotation of the turbine blades provided at the lower part, and this is alleviated to create a uniform circulating flow.

With the above three measures, even if an immobilized carrier is used, the inflow air can be made finer, completely mixed, and the carrier can be floated sufficiently, resulting in improved quality of treated water, stable treatment, and high concentration ML.
VSS is maintained.

[0021]

EXAMPLE An aeration part (21 m ³ ) and a sedimentation part (11) of a water tank body (4.25 mφ × 4.5 m) are formed by an inner cylinder and an outer cylinder.
m ³ ), and fine particles of granulated blast furnace slag having a particle size of 1 to 50 μm were added to the aeration section so that the floating concentration was 2000 mg / l. Further, in the center of the water tank, an agitator with a lower turbine blade and an upper propeller blade was installed, and a fine bubble diffusing pipe was placed on the entire bottom surface of the aeration section for aeration.

Raw water BOD concentration 120 mg / l, SS13
Domestic wastewater of 0 mg / l was supplied, and continuous treatment was performed with a residence time of 3 hours in the aeration section. As a result, stable treatment can be performed, and the treated water BOD concentration is 13 mg / l and SS concentration is 7 mg.
It was / l. During this period, neither peeling of water granules, disassembly of sludge, nor precipitation of water granules was observed.

[0023]

INDUSTRIAL APPLICABILITY In the activated sludge treatment using the immobilized carrier in the high-speed aeration settling tank, stable treatment can be carried out without causing the carrier to be peeled, sludge to be dismantled, and the carrier to be deposited and accumulated.

[Brief description of drawings]

FIG. 1 is a sectional view of a biological sewage treatment apparatus of the present invention.

[Explanation of symbols] 1 water tank body 2 inflow port 3 air diffuser 4 inner cylinder 5 aeration part 6 activated sludge 7 sludge discharge port 8 outer cylinder 9 circulation part 10 sedimentation part 11 outflow groove 12 agitator 13 inner cylinder umbrella part W inflow water W ₁ Primary treated water W ₂ Secondary treated water W ₃ Supernatant water AO, A Air D ₁ Excess sludge

Claims (3)

(57) [Claims] 1. A lower part of an agitator installed in an aeration section of a high-speed aeration sedimentation basin using a fixed carrier is a turbine blade,
A biological sewage treatment device, characterized in that the upper part is a propeller or paddle blade and the fine bubble diffusing pipe is arranged on the bottom face of the aeration part. 2. The biological sewage treatment apparatus according to claim 1, wherein the immobilization carrier is ground granulated blast furnace slag powder. 3. The biological sewage treatment apparatus according to claim 1, wherein a backflow prevention mechanism is provided in the fine bubble diffusing tube.