JP2009039673A - Apparatus and method for treating waste water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for treating waste water in which the air to be supplied to a water tank is used so that filthy materials are decomposed efficiently by an activated sludge microbe and the inside of the water tank is agitated satisfactorily. <P>SOLUTION: The apparatus for treating waste water, in which sewage and the activated sludge microbe are aerated and agitated in the water tank 1 so that filthy materials in the sewage are decomposed by the activated sludge microbe, is provided with; an air diffusion unit 10 arranged in the water tank 1 for generating air bubbles; and an agitator 2 arranged in the water tank 1 for producing water currents upward and downward almost in the vertical direction and producing whirling currents different in the upper part and lower part of the water tank 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a wastewater treatment apparatus and a wastewater treatment method for treating sewage or sewage, and more particularly to a wastewater treatment apparatus and a wastewater treatment method for aeration and agitation of activated sludge mainly composed of microorganisms and sewage that has flowed in.

  In a wastewater treatment facility such as a sewage treatment plant, when treating sewage or sewage that has flowed in, the sewage or sewage and activated sludge mainly composed of microorganisms are mixed and stirred in a water tank, and air is supplied to the water tank. By aeration, activated sludge microorganisms use oxygen in the air to decompose sewage or pollutants in the sewage.

Various methods have been proposed as aeration / stirring methods. Among them, a device having fine pores is installed in a water tank, and aeration device that performs aeration / stirring by supplying air from the outside to the device. There is a thing of patent document 1 as an example.
This air diffuser supplies air into the water tank, and the introduced air moves in the water tank as an upward flow, so that a flow is generated in the solution in the water tank and the inside of the tank can be stirred. .
At that time, by providing a mechanism other than the air diffuser, a method for efficiently performing the stirring by the air diffuser has also been proposed.
JP 2007-014898 A Japanese Examined Patent Publication No. 06-077752

By the way, the air diffuser is originally intended to supply the amount of air or oxygen required by the activated sludge microorganisms in the water tank, but at the same time, it is also required to play the role of stirring in the tank. In normal operation, more air is supplied than the amount of air required by the activated sludge microorganisms.
For this reason, the air supplied into the water tank moves through the water tank as an upward flow, but not all of the oxygen in the supplied air is utilized by the activated sludge microorganisms, most of which remains unused. Released into the atmosphere.
On the other hand, in order to supply air to the air diffuser installed in the water tank, it is necessary to send pressurized air from a blower provided outside the water tank, and the energy required for that is enormous.
That is, in the conventional aeration / stirring method using only the air diffuser, more air than is necessary for wastewater treatment by the activated sludge microorganisms is supplied, in other words, extra energy is input.

  In view of the problems of the above-described conventional wastewater treatment apparatus and wastewater treatment method, the present invention efficiently uses the air supplied to the water tank to decompose pollutants by the activated sludge microorganisms, and the water tank is sufficiently stirred. It is an object of the present invention to provide a wastewater treatment apparatus and a wastewater treatment method which are made.

  In order to achieve the above object, the wastewater treatment apparatus of the present invention is a wastewater treatment apparatus for decomposing contaminants in sewage by activated sludge microorganisms by aeration and agitation of sewage and activated sludge microorganisms in the tank. An air diffuser for generating bubbles is provided in the interior, and a stirrer is provided in the aquarium to generate water flows in the vertical direction and to generate different swirling flows in the upper and lower parts of the aquarium.

  In order to achieve the same object, the wastewater treatment method of the present invention is a wastewater treatment method in which sewage and activated sludge microorganisms are aerated and agitated in a water tank to decompose pollutants in the sewage by activated sludge microorganisms. In addition, air bubbles are generated in the water tank by the air diffuser, and water flows are generated in the vertical direction by a stirrer installed in the water tank, and different swirling flows are generated in the upper and lower parts of the water tank.

  In this case, the stirrer has a pipe in the vertical direction, and the liquid in the water tank can be sucked from the suction port provided near the center of the pipe and discharged from the upper and lower parts of the pipe.

  Further, a drive shaft is disposed in the pipe, and an impeller is provided on the upper and lower portions of the pipe on the drive shaft. By rotating each impeller, the liquid in the water tank can be discharged from the upper and lower portions of the pipe. .

  Also, the diffuser can be installed near the lower opening of the pipe.

  In addition, an air diffuser can be installed near the inlet of the pipe.

  According to the wastewater treatment apparatus and the wastewater treatment method of the present invention, in the wastewater treatment in which sewage and activated sludge microorganisms are aerated and agitated in a water tank to decompose the pollutants in the sewage by the activated sludge microorganisms. In addition to generating bubbles in the water tank, the stirrer installed in the water tank causes a water flow in the vertical direction and generates a different swirling flow in the upper and lower parts of the water tank. The residence time of the air in the water tank can be lengthened, so that the air can be efficiently used for the decomposition of the pollutant by the activated sludge microorganisms and the water tank can be sufficiently stirred.

  In addition, the stirrer has a pipe in the vertical direction and sucks the liquid in the water tank from the suction port provided in the vicinity of the center of the pipe and discharges it from the upper and lower parts of the pipe, thereby causing different swirling flows in the upper and lower parts of the water tank. Ascending and descending jet streams can be generated.

  Also, by disposing the drive shaft in the pipe, and providing the drive shaft with an impeller at the top and bottom of the pipe, by rotating each impeller, the liquid in the water tank is discharged from the top and bottom of the pipe, Ascending jet flow and descending jet flow that generate different swirling flows at the upper and lower parts of the water tank can be easily generated.

Further, by installing the diffuser near the lower opening of the pipe, the bubbles supplied from the diffuser are guided to the bottom of the water tank by the downward jet flow.
Thereafter, the bubbles rise due to buoyancy applied to themselves, but since the bubbles are once guided to the bottom, the residence time therebetween increases.

  Further, by installing the diffuser near the suction port of the pipe, the supplied bubbles are guided from the suction port to the stirrer, and then released into the water by the downward jet flow. In this case as well, the residence time is increased because it is once guided to the bottom.

  Hereinafter, a wastewater treatment apparatus and a wastewater treatment method according to the present invention will be described with reference to the drawings.

FIG. 1 shows a first embodiment of the wastewater treatment apparatus and wastewater treatment method of the present invention.
In the wastewater treatment apparatus and wastewater treatment method of the present embodiment, air or oxygen required by the activated sludge microorganisms is blown by air pressurized from a blower provided outside the water tank to the diffuser installed in the water tank. , And supplied as bubbles from the diffuser.

As for stirring in the water tank, a water flow is generated vertically and vertically at one or a plurality of positions in the water in the water tank, and the state of the flow is shown in FIG.
In the following, the flow in the left half of FIG. 1 will be described, but the same description can be made for the flow in the right half.

  The ascending jet flow A generated upward in the vertical direction by the stirrer 2 provided substantially at the center of the water in the water tank 1 changes in the horizontal direction as it reaches the vicinity of the water surface and moves away from the stirrer 2, that is, the water tank 1 The surface flow B is directed toward the wall surface, but the flow direction is changed again by the collision with the wall surface to become the surface downward flow C.

  On the other hand, the downward jet stream D generated downward in the vertical direction changes the flow in the horizontal direction as it reaches the vicinity of the bottom of the water tank, and becomes a bottom flow E in the direction away from the stirrer 2, that is, toward the water tank wall surface. In the vicinity, the flow direction is changed again by the collision with the wall surface, and the bottom upward flow F is obtained.

These surface downflow and bottom upflow collide in the vicinity of the middle tank of the water tank, but there is also suction by the stirrer 2 and a middle layer suction flow G flows from the wall surface of the water tank toward the stirrer 2.
The upper swirl flow H constituted by a series of the upward jet flow A, the surface layer flow B, the surface layer downward flow C, and the middle layer suction flow G, or the downward jet flow D, the bottom flow E, the bottom upward flow F, and The lower swirling flow I constituted by the middle layer suction flow G has the ability to sufficiently stir the upper or lower part of the water tank, and the fluid between the upper and lower portions in addition to the flow by the middle layer suction flow G in the vicinity of the middle layer. The replacement occurs.

  In particular, the upper swirling flow H acts like a lid, while bubbles generated from the air diffuser installed in the water tank are released from the surface of the water tank to the atmosphere by buoyancy applied to the bubbles themselves, and By introducing the bubbles into the water tank again by the surface downflow C, the residence time of the bubbles in the water tank is lengthened, so that the activated sludge microorganisms in the water tank can efficiently use the air or oxygen.

  With respect to the stirrer 2, the pipe has a pipe in the vertical direction and sucks the liquid in the water tank from the suction port provided near the center of the pipe, and has a structure for discharging the liquid from the upper and lower parts of the pipe. And a downward jet flow D can be generated.

An example of a stirrer that performs such a function is shown in FIG.
A rotary shaft 4 is connected to the driving device 3, and an upper screw 5 and a lower screw 6 are respectively attached to the rotary shaft 4.
In this case, the upper screw 5 is installed in the upper pipe 7 and the lower screw 6 is installed in the lower pipe 8.
A partition plate 9 is provided between the upper pipe 7 and the lower pipe 8.

As the rotating shaft 4 rotates, an upward flow is generated in the upper pipe 7 by the upper screw 5, so that a middle-layer suction flow G is generated as a flow flowing into the upper pipe, but the flow is divided into two by the partition plate 9. The flow that has been separated and passed between the upper pipe 7 and the partition plate 9 becomes a rising jet flow A as an outflowing flow.
Similarly, a downward flow is generated in the lower pipe 8 by the lower screw 6, and an intermediate suction flow G and a downward ejection flow D are generated.

On the other hand, when the air diffuser is installed near the lower opening of the pipe of the stirrer, the bubbles supplied from the air diffuser are guided to the bottom of the water tank by the descending jet flow D.
Thereafter, the bubbles rise due to buoyancy applied to themselves, but since the bubbles are once guided to the bottom, the residence time therebetween increases.

Alternatively, when an air diffuser is installed near the suction port in the center of the pipe, the supplied bubbles are guided from the suction port to the stirrer, and then released into the water by the downward jet flow D. In this case as well, the residence time is increased because it is once guided to the bottom.
As described above, since the residence time of the bubbles supplied in the water is increased, the amount of oxygen dissolved in the bubbles is increased, and thus efficient aeration is performed.

In FIG. 3, an example of the installation condition in a reaction water tank and a driving | running state at the time of applying the waste-water-treatment apparatus and waste-water-treatment method by this invention is shown.
In a water tank 1 for aeration and agitation of activated sludge microorganisms and sewage, a stirrer 2 is installed in the upper part of the water tank. In the agitator 2, a rotating shaft 4 is connected to a driving device 3, and an upper screw 5 and a lower screw 6 are respectively attached to the rotating shaft 4.
The upper screw 5 and the lower screw 6 are installed so as to be accommodated in the upper pipe 7 and the lower pipe 8, respectively, and a partition plate 9 is provided between the upper pipe 7 and the lower pipe 8.

As the rotating shaft 4 connected to the driving device 3 rotates, an upward flow is generated in the upper pipe 7 by the upper screw 5 and a downward flow is generated in the lower pipe 8 by the lower screw 6. The middle layer suction flow G is generated as the flow for supplying the gas.
The middle layer suction flow G is divided by a partition plate 9 provided between the upper pipe 7 and the lower pipe 8, and the flow that has passed through the lower pipe 8 is the upward jet flow A as the flow that has passed through the upper pipe 7. As descending jet flows D, they are each discharged into the water of the water tank 1.

Ascending jet flow A changes the flow in the horizontal direction as it reaches the vicinity of the water surface and becomes surface layer flow B, but changes the flow direction again near the water surface and becomes the surface layer downward flow C.
On the other hand, the downward jet flow D changes the flow in the horizontal direction as it reaches the vicinity of the bottom of the aquarium and becomes the bottom flow E, and the flow direction changes again in the vicinity of the bottom wall of the aquarium and becomes the bottom upflow F.
Although the surface downflow C and the bottom upflow F collide in the vicinity of the middle layer of the water tank, the flow as the middle layer suction flow G is generated by the stirrer 2 as described above, and thus the upper swirl flow H is generated as a series of flows. And a lower swirl I is formed.

On the other hand, an aeration device 10 is installed in the water tank 1 to supply oxygen to the activated sludge microorganisms. In the present embodiment, it is installed at the bottom of the water tank 1.
Air is introduced into the air diffuser 10 from a blower 11 provided outside the tank, and the bubbles 12 are supplied into the water in the water tank 1.
The bubbles 12 supplied into the water try to rise in the vertical direction by buoyancy applied to the water, but at the same time, the bottom of the water tank is moved in the horizontal direction in accordance with the flow of the lower swirl flow I formed by the stirrer 2.
Accordingly, oxygen can be supplied to a place where bubbles do not reach without the stirrer 2, that is, a place where oxygen cannot be supplied to the activated sludge microorganisms.
In addition, although the bubbles 12 that have reached the vicinity of the middle layer of the water tank 1 try to rise further in the vertical direction, some of them are strongly attracted in the horizontal direction by the middle layer suction flow G, and then guided to the stirrer 2. A part is re-introduced into the lower part of the aquarium 1 as a downward jet flow D, that is, as a downward flow in the vertical direction.

The bubbles 12 that have not been guided to the stirrer 2 further move to the surface of the water tank by buoyancy, but part of the bubbles 12 ride on the upper swirl flow H and are guided vertically downward to the middle of the water tank by the surface downflow C. It is burned.
In this way, some of the bubbles 12 supplied into the water tank 1 by the air diffuser 10 are not released into the atmosphere by moving vertically upward due to buoyancy applied to themselves, but are formed by the stirrer 2. By following the downward flow, the water tank 1 is further retained.
The increase in the residence time of the bubbles 12 in the water tank 1 means that the oxygen in the bubbles 12 can be dissolved in the water in the water tank 1, and the air supplied from the blower 11 is efficiently used. Will be.

In FIG. 4, the other example of the installation condition in a reaction water tank at the time of applying the waste-water-treatment apparatus and waste-water-treatment method by this invention and an operating condition are shown.
In a water tank 1 for aeration and agitation of activated sludge microorganisms and sewage, a stirrer 2 is installed in the upper part of the water tank, and an upper swirl flow H and a lower swirl flow I are generated in the water tank 1 by the stirrer 2.
Further, an air diffuser 10 is installed immediately below the stirrer 2, and air supplied from a blower 11 provided outside the tank is introduced into the water tank 1 as bubbles 12.

The bubble 12 tends to rise due to its buoyancy, but is guided to the bottom of the water tank according to the lower swirl I generated by the stirrer 2 and then rises to the middle part of the water tank.
The bubbles 12 that have reached the vicinity of the middle layer of the water tank 1 try to rise further in the vertical direction, but a part of them is strongly drawn in the horizontal direction by the middle layer suction flow G, and then led to the stirrer 2 and a part thereof. Rides on the descending jet flow D, that is, as a downward flow in the vertical direction, is reintroduced into the lower part of the water tank 1.

The bubbles 12 that have not been guided to the stirrer 2 further move to the surface of the water tank due to buoyancy, but part of the bubbles 12 ride on the upper swirl flow, that is, the surface downflow C leads to the water tank middle layer vertically downward. It is burned.
In this way, some of the bubbles 12 supplied into the water tank 1 by the air diffuser 10 are not released into the atmosphere by moving vertically upward due to buoyancy applied to themselves, but are formed by the stirrer 2. By following the downward flow, the water tank 1 is further retained.
The increase in the residence time of the bubbles 12 in the water tank 1 means that the oxygen in the bubbles 12 can be dissolved in the water in the water tank 1, and the air supplied from the blower 11 is efficiently used. Will be.

  As mentioned above, although the waste water treatment apparatus and waste water treatment method of this invention were demonstrated based on the Example, this invention is not limited to the structure described in the said Example, In the range which does not deviate from the meaning, Its configuration can be changed.

  The wastewater treatment apparatus and the wastewater treatment method of the present invention increase the residence time of the air supplied from the air diffuser in the water tank, thereby efficiently using the air to decompose pollutants by the activated sludge microorganisms. Since it has the property of sufficiently performing internal stirring, it can be suitably used for aeration / stirring wastewater treatment equipment and wastewater treatment methods aimed at energy saving.

It is sectional drawing which shows 1st Example of the wastewater treatment apparatus and wastewater treatment method of this invention. It is sectional drawing which shows the 2nd Example. It is sectional drawing which shows the 3rd Example. It is sectional drawing which shows the 4th Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Water tank 2 Stirrer 3 Drive apparatus 4 Rotating shaft 5 Upper screw 6 Lower screw 7 Upper pipe 8 Lower pipe 9 Partition plate 10 Air diffuser 11 Blower 12 Air bubbles A Ascending jet flow B Surface flow C Surface descending flow D Downward jet flow E Bottom flow F Bottom upflow G Middle layer suction flow H Upper swirl flow I Lower swirl flow

Claims (10)

  In a wastewater treatment device that decomposes pollutants in sewage with activated sludge microorganisms by aeration and agitation of sewage and activated sludge microorganisms in the water tank, an aeration device that generates bubbles in the water tank is provided, A wastewater treatment apparatus, wherein a stirrer is installed in a water tank to generate water flows in the upper and lower directions and to generate different swirling flows in the upper and lower parts of the water tank.   The waste water treatment apparatus according to claim 1, wherein the stirrer has a pipe in the vertical direction and sucks the liquid in the water tank from a suction port provided near the center of the pipe and discharges the liquid from the upper and lower parts of the pipe.   A drive shaft is disposed in the pipe, and an impeller is provided on the upper and lower portions of the pipe on the drive shaft, and each impeller is rotated to discharge liquid in the water tank from the upper and lower portions of the pipe. The wastewater treatment apparatus according to claim 2.   4. A wastewater treatment apparatus according to claim 2, wherein a diffuser is installed in the vicinity of the lower opening of the pipe.   The waste water treatment apparatus according to claim 2 or 3, wherein an air diffuser is installed in the vicinity of the suction port of the pipe.   In the wastewater treatment method in which sewage and activated sludge microorganisms are aerated and agitated in the aquarium, the pollutants in the sewage are decomposed by the activated sludge microorganisms. A wastewater treatment method characterized by causing a water flow to be generated in a substantially vertical direction up and down by an installed stirrer and generating different swirling flows in an upper part and a lower part of a water tank.   The wastewater treatment method according to claim 6, wherein the stirrer has a pipe in the vertical direction and sucks the liquid in the water tank from a suction port provided near the center of the pipe and discharges the liquid from the upper and lower parts of the pipe.   A drive shaft is disposed in the pipe, and an impeller is provided on the upper and lower portions of the pipe on the drive shaft, and each impeller is rotated to discharge liquid in the water tank from the upper and lower portions of the pipe. The wastewater treatment method according to claim 7.   The wastewater treatment method according to claim 7 or 8, wherein the air diffuser is installed in the vicinity of the lower opening of the pipe.   The wastewater treatment method according to claim 7 or 8, wherein an air diffuser is installed in the vicinity of the suction port of the pipe.

Images