JP3328487B2 - Carrier return device for aeration tank - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to activated sludge.
Activated sludge put into the aeration tank to be treated
The present invention relates to an aeration tank carrier returning device for returning a carrier holding a carrier .

[0002]

2. Description of the Related Art FIG. 3 is a conceptual diagram showing a conventional carrier return device for an aeration tank , which is generally called a basic system. In FIG. 3, reference numeral 1 denotes sewage flowing in an aeration tank (not shown) in the direction of arrow X. It is. Reference numeral 2 denotes a carrier formed of, for example, an organic polymer compound, a flexible polyurethane foam, or the like in a cubic shape and having a substantially homogeneous network structure over the entire volume. Microorganisms are present in the network structure. A plurality of the carriers 2 are put into the sewage 1 and flow along with the flow of the sewage 1.

An opening 3 is opened downward.
It is a suction tube having a. Numeral 4 is connected to the upper end of the suction pipe 3 through a right-angle elbow.
The discharge pipe 4 extends to the upstream side of the
It is located above the water surface of the sewage water 1 and has an opening 4a at its upstream end that opens toward the water surface.
Reference numeral 5 denotes an air pipe for supplying compressed air into the suction pipe 3 from a compressed air supply source (not shown) in the vicinity of the opening 3a of the suction pipe 3.

Next, the operation will be described. The carrier return device of the basic type shown in FIG. 3 supplies compressed air into the suction pipe 3 via the air pipe 5 so that the waste water 1
To generate air bubbles. As a result, the sewage 1 in the suction pipe 3 has a smaller apparent specific gravity than the external sewage 1 and is pushed up by an amount corresponding to the difference in specific gravity. At the same time as the sewage 1 is pushed up, the carrier 2 mixed in the sewage 1 is also pushed up. The mixed fluid composed of the sewage 1, the carrier 2 and the air bubbles passes through the discharge pipe 4 from the opening 4 a to the upstream side of the sewage 1 Is discharged. That is, with respect to the suction amount Q of the wastewater 1 and the carrier 2 and the supply amount q of the compressed air, the discharge amount Qu from the opening 4a becomes Qu = Q + q. Diameter and discharge pipe 4
Are formed substantially the same in diameter.

FIG. 4 is a conceptual diagram showing a carrier return device of a conventional aeration tank generally called a separation tank system. In the carrier return device of the basic system shown in FIG. The separation tank 6 is interposed at the connection portion between the discharge tank 4 and the discharge tank 4.

In this case, the sewage 1, carrier 2 and air bubbles in the suction pipe 3 are separated into sewage 1 and carrier 2 and air in the separation tank 6, and the air is exhausted from the upper part of the separation tank 6, while the sewage 1 And the carrier 2 passes through the discharge pipe 4 and the opening 4a
From the sewage 1 to the upstream side. That is, the discharge amount Qu from the opening 4a becomes Qu = Q. Therefore, in the carrier returning device of the separation tank type, the diameter of the suction pipe 3 is formed larger than the diameter of the discharge pipe 4.

[0007]

Since the conventional carrier returning device is constructed as described above, in the carrier returning device of the basic type, the diameter of the discharge pipe 4 having a large length is reduced by the suction pipe 3.
(See FIG. 3). Further, in the carrier return device of the separation tank type, the separation tank 6 must be newly provided (see FIG. 4), so that there is a problem that the equipment cost is increased. Furthermore, since the discharge pipe 4 is located above the water surface of the sewage 1, the head H must be set larger as the return distance, that is, the length of the discharge pipe 4 in the longitudinal direction increases, and the pumping efficiency (pumping efficiency) Ratio of the work required to compress the air) is about 20% to 30
%, Especially when the carrier 2 is mixed in the sewage 1, there is a problem that it becomes as low as about 11%.
In addition, especially in the carrier return device of the basic type shown in FIG. 3, the transfer distance of the mixed fluid is long, so that there is a problem that the operating cost is promoted.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to reduce the equipment cost, and at the same time, return the carrier of the aeration tank to improve the pumping efficiency and reduce the operation cost. The aim is to obtain a device.

[0009]

A carrier return device for an aeration tank according to the present invention is disposed below the water surface in the aeration tank, and is provided downstream of the aeration tank.
A suction pipe having an opening for sucking the carrier by opening at the upper end of the aeration tank connected to the suction pipe;
A discharge pipe having an opening which is opened on the side and discharges the carrier, and gas supply means for supplying gas to the discharge pipe.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. 1 and 2, 1 is an aeration tank T
This is sewage flowing in the longitudinal direction (that is, the direction of arrow X in FIG. 1) in the inside (shown only in FIG. 2). Reference numeral 2 denotes a carrier formed of, for example, an organic polymer compound, a flexible polyurethane foam, or the like, in a cubic or rectangular shape, and having a substantially homogeneous network structure over the entire volume, such as bacteria or the like inside the network structure. Contains microorganisms. This carrier 2
Are put into the sewage 1 in the aeration tank T (for example, an amount corresponding to, for example, about 5% to 30% of the total volume of the aeration tank T), and the sewage 1 is aerated from the diffuser S. It flows with the flow of. S is an air diffuser that diffuses air or pure oxygen into the sewage 1 to supply oxygen to the microorganisms contained in the carrier 2.

Reference numeral 11 denotes a suction pipe arranged along the longitudinal direction of the aeration tank T, and an opening (suction part) 11a opened on the side (downstream side) opposite to the arrow X direction.
have. Therefore, the entirety of the suction pipe 11 is
Located inside. 12 is an opening 11 of the suction tube 11
This is a discharge pipe connected to an end (upstream side) opposite to a through a curved pipe body, and has an opening (discharge part) 12a opened upward at its upper end. , This opening 12
a protrudes above the surface of the wastewater 1. Depending on the state, it may not be necessary to protrude above the water surface. Reference numeral 13 denotes an air pipe (gas supply means) for supplying compressed air (gas) from a compressed air supply source such as a blower (not shown) into the discharge pipe 12. A compressed air supply system is formed by the air pipe 13 and the compressed air supply source. Is configured.

Here, the position where the suction pipe 11 is disposed is the position of the sewage 1.
If it is medium, it can be set freely within a range that does not hinder the flow and stirring of the sewage 1 in the aeration tank T or the air diffusion of the air diffuser S. In FIG. 1, the lower end of the discharge pipe 12 is disposed so as to be located above the suction pipe 11. However, as shown by a dotted line, this is set so as to be located below. Air tube 1
It is also possible to set the outlet 3 deep.

Next, the operation will be described. By supplying compressed air from the compressed air supply source into the discharge pipe 12 through the air pipe 13, bubbles are generated in the wastewater 1 inside the discharge pipe 12. As a result, the sewage 1 inside the discharge pipe 12 has a smaller apparent specific gravity than the sewage 1 outside, and the sewage 1 from the opening 11a of the suction pipe 11 is reduced by an amount corresponding to the difference in specific gravity.
And the carrier 2 mixed therein is sucked. And
These are pushed up as a mixed fluid with air bubbles inside the discharge pipe 12, and then discharged to the upstream side of the wastewater 1 from the opening 12a. That is, with respect to the suction amount Q of the sewage 1 and the carrier 2 and the supply amount q of the compressed air, the discharge amount QM from the opening 12a is QM = Q + q.

According to such a carrier returning device, only the sewage 1 and the carrier 2 pass through the suction pipe 11, and the mixed fluid passes only through the discharge pipe 12. Therefore, in particular, the diameter of the suction pipe 11 having a long return distance is changed to the discharge pipe 12.
Can be set smaller than the bore size, and the equipment cost is reduced. Further, since the suction pipe 11 is provided in the sewage 1, the head H can be reduced and the pumping efficiency can be significantly improved. Further, since the transfer distance of the mixed fluid is shortened, the operating cost can be reduced.

In the above embodiment, as shown in FIG.
The discharge pipe 12 is connected to the end of the suction pipe 11 via a curved pipe, but the present invention is not limited to this. For example, the discharge pipe may be fitted into the suction pipe 11, flange-bonded, welded, or the like. Or the like, and may be formed integrally with the suction tube 11. In addition, the end of the suction tube 11 is not limited to a curved tube as described above, and may have any shape as long as the carrier 2 can flow, such as a straight tube. Further, in the above embodiment, the opening (discharge portion) 12a of the discharge pipe 12 is formed to protrude above the water surface. However, the shape is not limited to this, and the discharge portion may be formed below the water surface or below the water surface. There may be. Further, the opening 12a may be a front opening or a partially closed one, and the position and shape of the opening 12a are not limited as long as the carrier 2 can be smoothly returned. That is, by supplying compressed air or gas to the discharge pipe 12, the opening 1 of the suction pipe 11 is opened.
1a, the wastewater 1 and the carrier 2 are sucked, and a mixed fluid of these and the above-mentioned compressed air or gas is supplied to the opening 12 of the discharge pipe 12.
a.

In the above embodiment, the air pipe 13 is connected to the lower part of the discharge pipe 12. However, for example, as shown by a dotted line in FIG. Is also good. Further, the supply gas from the air pipe 13 may be other gas such as nitrogen gas in addition to the compressed air. Further, an odor gas generated in the tank may be captured and used as a gas supply source. According to this configuration, it is possible to provide a simpler and lower-cost apparatus since a structure for discharging the odor gas to the outside of the tank can be used together without separately providing the structure.

[0017] In the above embodiment, although the example where one carrier return device according to the present application, the processing tank (Eareshi
If the tank is large, two or more tanks may be installed.
Further, a plurality of branch pipes may be formed in the suction pipe 11 and the discharge pipe 12 even if only one. With these configurations, the carrier 2 can be uniformly and efficiently transferred to the entire large processing tank.

[0018]

As is evident from the foregoing description, according to the present invention, is disposed below the water surface in the aeration tank, Earesho
A suction tube having an opening for sucking the carrier open at the downstream of Ntanku, connected to the suction tube, aeration
Since the discharge pipe having an opening which is opened on the upstream side of the tank and discharges the carrier and a gas supply means for supplying gas to the discharge pipe are provided, suction with a large transfer distance of the wastewater and the carrier is provided. The diameter of the pipe can be reduced,
This has the effect of reducing equipment costs. In addition, since the head can be reduced, there is an effect that the water pumping efficiency can be improved. Further, the distance for transferring the mixed fluid of the sewage, the carrier and the bubbles can be shortened, so that the operation cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing a conceptual configuration of a carrier returning device according to a first embodiment of the present invention.

FIG. 2 is a side sectional view showing a conceptual configuration of the carrier returning device according to the first embodiment of the present invention.

FIG. 3 is a front sectional view showing a conceptual configuration of an example of a conventional carrier returning device.

FIG. 4 is a front sectional view showing a conceptual configuration of another example of the conventional carrier returning device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sewage 2 Carrier 11 Suction pipe 12 Discharge pipe 13 Air pipe (gas supply means)

Claims (1)

(57) [Claims] 1. A carrier returning device aeration tank to return your carrier for holding the activated sludge by fluidized aeration tank from the downstream side of the aeration tank to the upstream side, is disposed below the water surface in the aeration tank , Air
A suction pipe which is opened downstream of the aeration tank and has an opening for sucking the carrier, connected to the suction pipe, and connected to the upstream of the aeration tank.
A discharge pipe having an opening opened to ejecting the carrier, carrier return device aeration tank, characterized in that a gas supply means for supplying gas to the discharge pipe.