JP3209874B2 - Aeration device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an efficient aerator for use in water treatment such as sewage treatment and industrial wastewater treatment.

[0002]

2. Description of the Related Art Conventionally, an activated sludge method has been used in water treatment such as sewage treatment and industrial wastewater treatment. In the activated sludge method, generally, water to be treated that has passed through a sand basin and a first sedimentation basin is introduced into an aeration tank, and is aerated with an aeration device such as a diffuser plate installed in the tank, and the activated sludge in the tank is stirred. By supplying oxygen while mixing, BOD, nitrogen, and the like in the water to be treated are removed by the action of activated sludge. Then, a part of the activated sludge mixed water in the aeration tank is led to the final sedimentation basin to settle the activated sludge, and the supernatant water in the final sedimentation basin is sent to a disinfection facility, and the disinfected water is discharged as treated water.

[0003] By the way, the conventional aeration tank is about 5 m in depth. However, when the capacity needs to be increased, it is often necessary to cope with the problem by increasing the depth. Due to an increase in the amount, recently, what is called a deep aeration tank having a depth of 5 m or more, for example, a depth of 10 to 20 m, or an ultra-deep aeration tank having a depth of about 100 m has come to be seen. In such deep or ultra-deep aeration tanks, conventional aerators such as diffusers do not have sufficient oxygen supply and stirring capabilities, and
Various proposals have been made because the discharge pressure of the blower becomes extremely large and the power efficiency of the aeration device decreases.

For example, an aeration tank called a deep shaft as shown in FIGS. 4 and 5 is known. The deep shaft 1 includes a shaft 4 including a descending flow path 2 and an ascending flow path 3 and a head tank 5.
Descends the descending flow path 2 and reverses at the shaft bottom 4a,
A circulating flow that rises in the ascending flow path 3 and returns to the descending flow path 2 again via the head tank 5 is formed. 7 is a raw water supply pipe, 8
Is a water pipe leading to the degassing equipment, and 9 is a sludge return pipe.

In the deep shaft of the air lift system shown in FIG. 4, the upper end of the descending flow path 2 is opened below the liquid level of the activated sludge mixture 6 and diffuser pipes 10a and 10b connected to a compressor 10 as an air supply means. Are guided to the middle of the descending flow path 2 and the ascending flow path 3, respectively. In such a configuration, air is blown into the ascending flow path 3 from the air diffuser 10b to generate an ascending liquid flow in the ascending flow path 3 by the air lift function, and the ascending liquid flow and the descending flow generated thereby. The descending liquid flow in the passage 2 generates a circulating liquid flow extending between the ascending flow path 3 and the descending flow path 2. When the liquid circulation is stabilized, air for water treatment is introduced into the descending flow path 2 from the air diffuser 10 a. I'm breathing.

[0006] In the pump-type deep shaft shown in FIG.
A circulation pump 13 is interposed in a pipe 12 connecting the upper end portion 11 and the inside of the head tank 5. Blower 14 as air supply means
Is connected to the inside of the down flow path 2. In such a configuration, the activated sludge mixed liquid 6 in the head tank 5 is pumped to the upper end portion 11 of the descending flow path 2 by the circulation pump 13, and the circulating liquid flow is generated by the head difference between the upper end portion 11 and the head tank 5. When the liquid circulation is stabilized, air for water treatment is blown into the down flow path 2 from the air diffuser 14a.

In both the air lift system and the pump system described above, the air blown into the descending flow path 2 becomes bubbles, which are mixed with the activated sludge mixture 6 descending in the descending flow path 2 and dragged to the shaft bottom 4a. Be included.
The speed of the mixed solution 6 in the descending flow path 2 is adjusted to 1-2 m / sec, which is sufficiently higher than the velocity at which the bubbles float in the still water, so that the bubbles do not rise in the descending flow path 2 and Is subjected to a large hydrostatic pressure in the shaft 4 according to its depth, and oxygen in the air is rapidly dissolved in the mixture 6.

[0008]

However, even in such aeration tanks, depending on the arrangement of a large number of diffuser plates for the purpose of supplying a large amount of air and the shape of the reaction tank, there is not enough space in the descending flow path. In some cases, it may be difficult to secure the mixed liquid flow rate. In addition, although the oxygen dissolving efficiency can be increased as the diffused water depth is increased, a large power is required for driving the compressor and the blower, so that there is a problem that the oxygen transfer power efficiency is reduced.

For this reason, it is conceivable to install a pump device for flowing the water to be treated downward in the downflow channel at the lower portion of the downflow channel, and to dispose an air diffuser plate at the upper portion in the downflow channel. In such a configuration, when inspecting or repairing the pump device, the straight pipe portion that constitutes the down flow path together with the pump device must be pulled up. The deeper the tank depth, the more time and effort required for this work. This not only increases the cost, but also increases the risk due to work at a high place.

The present invention solves the above problems, and provides an aeration apparatus which can be used irrespective of the shape of a reaction tank, can obtain high oxygen dissolution efficiency and oxygen transfer power efficiency, and can be maintained safely and easily. The purpose is to do so.

[0011]

In order to solve the above-mentioned problems, an aerator according to the present invention is disposed vertically in a reaction tank from below a certain depth of water to be treated to a bottom thereof, and gradually downwards. A drop-in tube formed at the upper end with a tapper to reduce the diameter,
A diffusing means which is opened at an upper part in the suction pipe and supplies oxygen-containing gas into the water to be treated, and an oxygen-containing gas and water to be treated which are installed at a lower part of the suction pipe and supplied by the diffusing means. Pump means for flowing down the inside of the suction pipe, wherein the suction pipe and the pump means are configured to be joined and separated freely, and guide means for guiding the vertical movement of the pump means, and the suction pipe is positioned above the pump means. And a support means for movably holding the pump means in an avoidance position which does not hinder the vertical movement of the pump means.

Further, in the aeration apparatus according to the present invention, the guide means is provided with guide columns which are provided on both sides in the radial direction of the pump means at an appropriate distance from the pump means, and are slid in the axial direction with respect to the guide columns. The guide means is movably engaged with the guide means for guiding the vertical movement of the pump means, and the support means is externally fitted to the guide pillar and is provided so as to be rotatable about the axis of the guide pillar. It is composed.

[0013]

According to the above construction, the water to be treated in the reaction tank flows downward in the suction pipe by the pumping action of the pump means and the guide action of the suction pipe. The turbulence is generated by flowing into the inside of the suction pipe from the inlet. For this reason, the oxygen-containing gas supplied from the air diffuser in the upper part of the suction pipe is entrained in the turbulent water to be treated, and the air bubbles are fragmented. Since it is rapidly dissolved in the water to be treated, the amount of oxygen dissolved in the water to be treated and the power efficiency are large. When checking or repairing pump means,
After the suction pipe is moved to the avoidance position where the vertical movement of the pump means is not hindered by the support means, the pump means is guided up by the guide means and lifted out of the tank. When the inspection or repair is completed, work in the reverse order,
The pump means is arranged at the lower part of the suction pipe. In this manner, maintenance of the pump means can be performed safely and easily without raising the drawing pipe.

Further, guide columns are provided on both sides of the pump means, and a guide for guiding the vertical movement of the pump means and a support rotating about the axis of the guide columns are attached to the guide columns. Therefore, installation of the aeration device can be easily performed.

[0015]

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1 to FIG. 3, reference numeral 15 denotes a reaction tank configured to store the water to be treated having a water depth of about 20 m. Inside the reaction tank 15, the treated water 16 mixed with the activated sludge is provided.
The aeration device 17 is installed at a substantially central position in the horizontal direction of the tank 15 by being immersed in the water 16 to be treated.
18 is a raw water supply pipe, 19 is a water pipe leading to a deaeration facility, 20
Is a sludge return pipe.

The aeration device 17 has a suction pipe 21 vertically arranged from below a certain depth to the bottom of the water 16 to be treated, and at the upper end of the suction pipe 21 is a spout whose diameter gradually decreases downward. 22 are formed. Aeration device 17
Further, an air diffuser such as an air diffuser 24 for supplying an oxygen-containing gas such as air 23 to the water 16 to be treated is opened at an upper part in the inlet pipe 21, for example, about 5 m below the liquid level, and supplied by the air diffuser 24. A pump device 25 for causing the air 23 and the water 16 to flow downward in the inlet pipe 21 is provided at a lower portion of the inlet pipe 21. The air diffuser 24 is connected to an air supply means such as a blower 26 outside the tank.

The pump device 25 has a hermetically sealed structure as shown in the figure, and has an inlet 27 connected to and separated from the lower end of the drawing pipe 21 and a lower and radially circumferential portion communicating with the inside of the device 25. And an impeller 30 driven by a driving means such as a submersible motor 29 inside. By driving the impeller 30, the air 23 and the water to be treated 16 in the inlet pipe 21 are introduced into the device 25 through the inlet 27, and are discharged to the outside of the device 25 through the outlet 28 while being stirred and mixed. Along with such introduction and discharge, the air 23 in the inlet pipe 21 and the water 16 to be treated flow downward at a flow rate of about 2 m / sec.

Reference numerals 31 and 32 denote guide columns which are provided on both sides of the pump device 25 in the radial direction at an appropriate distance from the pump device 25. Guides 33 and 34 for guiding the movement are attached. One end 33 of guides 33 and 34
a and 34a are fixed to the pump device 25, and the other end portions 33b and 34b are slidably engaged with the guide column 31 in the axial direction.

Reference numeral 35 denotes a support that movably holds the suction pipe 21 between an upper position of the pump device 25 and an avoidance position that does not hinder the vertical movement of the pump device 25. The support 35 is disposed at two places at appropriate intervals in the vertical direction, one end 35a of which is fixed to the lead-in tube 21 and the other end 35b is fitted around the guide column 31 so as to rotate around the axis of the guide column 31. It is freely rotatable.

As shown, the other end 34 of the guide 34
b is externally inserted into the guide post 32, but the other end 33 b of the guide 33 is inserted into a guide groove 31 a formed in the guide post 31, whereby the other end 3
It can move without being obstructed by 5b. Below the other end 35b of the support 35, a position fixing member 36 for preventing the support 35 from lowering is disposed.

The operation of the above configuration will be described below. In the reaction tank 15, in a state where raw water is supplied from the raw water supply pipe 18 and activated sludge is returned from the sludge return pipe 20,
The water 16 to be treated in the tank 15 is biologically treated by the activated sludge, and a part of the water 16 to be treated including the activated sludge flows out of the tank 15 through the water pipe 19.

The water 16 to be treated in the reaction tank 15 is
1 is drawn downward into the suction pipe 21 by the pumping action of the pump device 25 installed at the lower part of the pump 1 and the guiding action of the suction pipe 21, and at this time, the suction pipe 21 is gradually moved downward from the inlet 22. Turbulence is generated by flowing into the interior. Air 23 is supplied from the air diffuser 24 to the water 16 to be treated in such a turbulent state in the upper part of the suction pipe 21.

The supplied air 23 is entrained in the turbulent flow, and its air bubbles are fragmented to increase the contact ratio with the water 16 to be treated. Since the amount of dissolution increases, it is rapidly dissolved in the water 16 to be treated.

The water 16 to be treated and the air 23, which flow downward in the suction pipe 21 and reach their lower ends, flow into the pump device 25 through an inlet 27 and are stirred and mixed by an impeller 30 while being discharged. It is discharged radially downward from the outlet 28.

At this time, the air 23 is mixed with the water 16 to be treated while the bubbles are further miniaturized by the impeller 30 and the contact rate with the water 16 is increased. Becomes even larger.

The water 16 to be treated radially discharged downward from the discharge port 28 forms a circulating flow that rises near the side wall after reaching the bottom of the reaction tank 15. By forming such a circulating flow that circulates through the entire area in the tank, the contact ratio between the air and the water 16 to be treated is increased, and the water 16
The amount of oxygen dissolved in the oxygen further increases.

As described above, the contact ratio between the air 23 and the water 16 to be treated is increased by the fineness of the air bubbles 23 and the formation of the circulating flow.
The amount of air 23 dissolved in
The dissolved amount of oxygen in the reaction tank 15 becomes large, and the oxygen dissolving efficiency in the reaction tank 15 becomes high. Such an aeration device 17 is usually installed in a reaction tank having a depth of 5 m or more,
Reference numeral 4 is opened below the water depth where the power of the blower does not become excessively large, and the oxygen transfer power efficiency is also high.

When checking or repairing the pump device 25, the support pipe 35 is used to move the lead-in pipe 21 to an avoiding position where the vertical movement of the pump device 25 is not hindered. The pump device 25 is lifted out of the tank by being guided by the guides 33 and 34. When the inspection or the repair is completed, the operation is performed in the reverse order, and the pump device 25 is arranged below the inlet pipe 21. In this manner, maintenance of the pump device 25 can be performed safely and easily without raising the pull-in tube 21 as in the related art. Since the guides 33 and 34 and the supports 35 and 35 are attached to the guide columns 31 and 32, the aeration device 17 can be easily installed.

The guide 33 and the support 35 may be arranged so that the guide 33 can move without being disturbed by the support 35. Instead of the above-described configuration, for example, another guide column is erected and the guide column is mounted on the guide column. The support 35 may be attached.

[0030]

As described above, according to the present invention, turbulence is generated by the drinking spout at the upper end of the suction pipe, and the oxygen-containing gas is dispersed in the turbulent water to be treated in the upper part of the suction pipe. Thus, the water to be treated is lowered in the suction pipe. As a result, the oxygen-containing gas has a high contact ratio with the water to be treated, and receives a large head, so that the amount of dissolution in the water to be treated becomes large. It will be expensive.

Further, the suction pipe and the pump means are configured so as to be able to be joined and separated freely, and the suction pipe is moved to an avoiding position which does not hinder the vertical movement of the pump means, and then guided by the guide means so as to guide the pump. Since the means can be lifted out of the tank, inspection and repair of the pump means can be performed without raising the draw-in pipe as in the related art. As a result, the workability of the maintenance of the pump means is improved, and high safety can be obtained. This advantage increases as the tank depth increases.

Further, guide pillars are provided on both sides of the pump means, and a guide for guiding the vertical movement of the pump means and a support rotating about the axis of the guide pillar are attached to the guide pillars. Therefore, installation of the aeration device is easy.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a reaction tank provided with an aeration apparatus according to one embodiment of the present invention.

FIG. 2 is a main part cross-sectional view for explaining a lifting operation of a pump means in the aeration apparatus.

FIG. 3 is a vertical sectional view for explaining the operation of a pump means in the aeration apparatus.

FIG. 4 is an explanatory view showing one embodiment of a conventional ultra deep aeration tank.

FIG. 5 is an explanatory view showing another embodiment of a conventional ultra-deep aeration tank.

[Explanation of symbols]

 15 Reaction tank 16 Water to be treated 17 Aeration device 21 Inlet pipe 23 Air 24 Diffusion pipe 25 Pump device 26 Blower 31,32 Guide pillar 33,34 Guide 35 Support

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C02F 3/22 B01F 3/04

Claims (2)

(57) [Claims] 1. A suction pipe, which is vertically arranged from below a certain depth of water to be treated to a bottom in a reaction tank, and has a drinking opening formed at an upper end thereof and gradually decreasing in diameter, and a suction pipe at an upper part of the suction pipe. A diffuser for opening and supplying an oxygen-containing gas into the water to be treated, and an oxygen-containing gas and the water to be treated provided by the diffuser provided at a lower portion of the suction pipe and flowing downward in the suction pipe. And a guide means for guiding the vertical movement of the pump means, and a guide means for guiding the vertical movement of the pump means and the vertical position of the pump means. A support means for movably holding the evasion position so as not to hinder the movement of the aeration device. 2. The guide means is provided with guide pillars erected on both sides in the radial direction of the pump means at an appropriate distance from the pump means, and slidably engages with the guide pillars in the axial direction. And a guide for guiding the vertical movement of the pump means, and the support means comprises a support externally fitted to the guide post and rotatably mounted around the axis of the guide post. 1. The aeration apparatus according to 1.