KR20010094938A - Aeration system - Google Patents

Abstract

PURPOSE: To provide an aeration device high in oxygen moving efficiency and easy in maintenance. CONSTITUTION: A projecting pipe 11 projecting upward is provided on the downstream side from a feed pipe 2. An introducing pipe 17 for introducing feed air from the feed pipe 2 to an air chamber 27 is provided in a main body part 10. A guide member 43 engaged with the feed pipe 2 is provided in the side part of the introducing pipe 17. The introducing pipe 17 is fitted into the projecting pipe 11 accompanying the hanging and bringing down of the main body part 10. A diffusion port 38 for supplying the air in the air chamber 27 into a liquid to be treated is provided on the downstream side from the impeller 15. A discharge passage 42 is formed so as to discharge the mixed fluid of the air with the liquid to be treated obliquely downward by changing the flow direction.

Description

Aeration System {AERATION SYSTEM}

The present invention relates to an aeration device used for purification of sewage.

Background Art Conventionally, an aquatic mechanical aeration apparatus installed at the bottom of an aeration tank for aeration treatment of sewage in an aeration tank is well known. In the underwater mechanical aeration apparatus, an impeller mounted on a rotating shaft of an underwater motor is accommodated in a casing, and by a rotation of the impeller, the sewage is sucked into the casing and the fine bubbles are dispersed in the sewage to perform aeration. This type of aeration device is largely divided into a downwardly discharge type device that sucks a liquid to be processed from above and discharged from below and an upwardly discharge type device that sucks a liquid to be processed from below and discharges it from above. The downward discharge type device is advantageous for imparting a strong flow to the bottom of the aeration tank, and the upward discharge type device is particularly effective for deep aeration type aeration.

However, in order to improve the performance of the aeration device, it is effective to increase the dissolution efficiency (oxygen transfer efficiency) of oxygen to the liquid to be treated. Therefore, Japanese Utility Model Publication No. Hei 4-9039 discloses, in the upward discharge type aeration apparatus, an acid mechanism for supplying air to the liquid to be treated is formed not only on the upstream side of the van but also on the downstream side in order to increase the oxygen transfer efficiency. It was suggested to do.

However, even in the method of supplying air from both the upstream side and the downstream side of the vane, part of the supply air is supplied upstream of the vane, so that the vane passes through the vane together with the liquid to be treated. Therefore, the amount of the liquid to be passed through the vanes is reduced by the amount of supply air. Therefore, as the amount of air supplied increases, the amount of the liquid to be processed passing through the vanes decreases, and as a whole, there is a limit in improving the oxygen transfer efficiency.

In addition, as shown in FIG. 8, since the discharge passage 101 for discharging the mixed fluid of the liquid to be processed and air (bubble) is formed so as to discharge the mixed fluid to the side, bubbles having lighter specific gravity than the liquid to be treated are discharge passage. It became easy to accumulate in the upper part of 101, and it was hard to melt | dissolve sufficiently in the to-be-processed liquid on the structure of the discharge passage 101.

This invention is made | formed in view of this point, Comprising: It aims at providing the aeration apparatus with high oxygen transfer efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS The front view which broke and showed a part of aeration apparatus concerning this embodiment.

2 is a top view of the main body of the aeration apparatus according to the present embodiment.

3 is a view for explaining the shanghai work of the aeration apparatus main body, the front view of the state during the movement of the main body.

Figure 4 is a view for explaining the shanghaidong work of the aeration apparatus body portion, a front view of a state after the body portion installation.

Fig. 5 is a sectional view of the vicinity of the discharge passage of the aeration apparatus according to the present embodiment.

6 is a view corresponding to FIG. 1 according to a modification in which the mounting position of the guide member is changed.

7 is a diagram corresponding to FIG. 1 according to another modification.

Fig. 8 is a sectional view of the vicinity of a discharge passage of a conventional aeration apparatus.

<Description of Symbols for Main Parts of Drawings>

1: aeration device 2: air supply pipe

10: main body 11: protruding pipe (protrusion)

13: underwater motor 14: rotating shaft

15: vane 16: body casing (casing)

17: introduction tube 23: oil casing

27: air chamber 30: packing

36 discharge port 37 partition wall of air chamber

38: diffuser 41: partition member

42: discharge passage 43: guide member

47: suction port 50: support

In order to achieve the above object, the present invention, while forming the air diffuser only on the downstream side of the vane in order to increase the amount of the liquid to be passed through the vane as far as possible, while once directed upward to increase the stirring efficiency of air The mixed fluid of the to-be-processed liquid and air was bent so that the flow direction thereof could be discharged downward.

Specifically, the aeration device according to the present invention includes a main body having an underwater motor, a vane mounted on a rotating shaft of the submersible motor, a casing covering the periphery of the vane, and a supply for supplying air to the main body. An aeration device having an engine, wherein the casing discharges a suction port for sucking the liquid to be treated from below and a mixed fluid of the liquid to be processed and the air flowing upward through the casing downwardly while changing its flow direction. The discharge passage to be formed is formed, and the diffuser for supplying air from the air supply pipe to the liquid to be treated is formed on the downstream side of the van.

The underwater motor here means a motor in a broad sense including an underwater geared motor.

Thus, since the diffuser is formed on the downstream side of the van, there is no fear that the amount of the liquid to be passed through the van is reduced even when the air supply is large. Movement efficiency is improved. Conversely, the supply amount of air can be increased more than conventionally.

Since the discharge passage of the casing is formed to discharge the mixed fluid downwardly inclined, the flow direction of the mixed fluid rapidly changes from the upward direction downwardly. At this time, since a large centrifugal force acts on the mixed fluid, bubbles which are likely to collect on the upper part of the processing liquid are mixed with the processing liquid vigorously. Therefore, even when the air supply amount is large, the bubbles are sufficiently dispersed and mixed to improve the oxygen transfer efficiency.

Between the underwater motor and the vane in the main body portion, an annular air chamber is formed so as to surround the rotational axis of the underwater motor, and the air supply pipe is formed to introduce air into the air chamber. The diffuser is preferably formed by a slit gap between the lower edge of the partition wall of the air chamber and the vane.

As a result, the air introduced from the air supply pipe is once stored in the air chamber and then discharged from the slit-shaped gap between the lower edge of the air compartment partition wall and the vane, and is supplied to the liquid to be processed. As a result, air is efficiently supplied to the liquid to be processed on the downstream side of the van.

The casing is preferably provided with a support of a suitable height in the lower portion.

As a result, the casing is stably supported. In addition, since the support angle is formed at an appropriate height, a suction space of a sufficient size is secured in the lower portion of the casing to facilitate suction of the liquid to be processed.

By the way, the aeration device is used for a long time in the harsh environment and needs regular maintenance. For this reason, there is a need for an apparatus that can simplify the attachment and detachment of the air supply pipe for supplying air for easy maintenance.

Another aeration device according to the present invention includes a main body having an underwater motor, a vane mounted on a rotating shaft of the submersible motor, a casing covering the periphery of the vane, and extending in a vertical direction provided on the side of the main body. An aeration device having an air supply pipe, wherein a downstream side of the air supply pipe is bent upward, and the main body portion is detached from the downstream end of the air supply pipe along the shanghai east of the main body to supply air supplied from the air supply pipe into the casing. An inlet pipe for introducing the gas into the casing is provided, and the casing suctions the liquid to be treated from below, and the mixed fluid of the liquid and the air flowing upward through the casing to be inclined downward while changing its flow direction. The discharge passage which discharges is formed, and the diffuser for supplying air from the said introduction pipe to a to-be-processed liquid is the downstream side of a vane. It is to be formed in.

As a result, the diffuser is formed downstream of the van and the discharge passage of the casing is formed to discharge the mixed fluid downwardly inclined, so that the oxygen transfer efficiency is improved as described above.

In addition, an introduction pipe for introducing air supplied from the air supply pipe into the casing was provided, and the air supply pipe and the main body were connected by attaching and detaching the inlet pipe at a downstream end of the air supply pipe. It will be detached. Therefore, no special connection work for connecting the air supply pipe and the main body is necessary. This makes maintenance easier.

The main body part guides the main body part with the guide of the air supply pipe or with a guide rod separate from the air supply pipe, or guides the main body with both the air supply pipe and the guide rod. It is preferable to provide the guide member which one or both of these guide bars engage.

Thereby, since the main body part is guided by the guide member at the time of shanghai movement, it becomes easy to work up and down the main body part with respect to an aeration tank.

The downstream end of the air supply pipe forms a protrusion protruding upward, and the introduction pipe is connected to the air supply pipe by being fitted into the protrusion of the air supply pipe according to the suspension lowering of the main body.

As a result, the main body is simply suspended and lowered, and the introduction pipe is fitted into the protrusion of the air supply pipe so that the main body and the air supply pipe are automatically connected. In addition, by simply pulling up the main body, the introduction pipe is separated from the protrusion of the air supply pipe so that the connection between the main body and the air supply pipe is automatically released. Therefore, attachment and detachment of a main body part and an air supply pipe become very easy.

In the main body portion, an annular air chamber is formed between the submersible motor and the vane around the rotating shaft of the submersible motor, and the introduction pipe is formed to introduce air from the air supply pipe into the air chamber. The diffuser is preferably formed by a slit gap between the lower edge of the partition wall of the air chamber and the vane.

As a result, the air guided from the air supply pipe to the introduction pipe is once stored in the air chamber and then discharged from the slit-shaped gap between the lower edge of the air compartment partition wall and the vane to be supplied to the liquid to be processed. As a result, air is efficiently supplied to the liquid to be processed on the downstream side of the van.

The above and other objects and features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.

Embodiments of the present invention will be described below with reference to the drawings.

―Configuration of aeration device―

As shown in FIG. 1, the aeration device 1 is a so-called upward discharge submersible aeration device that is fixed to the air supply pipe 2 fixed to one support 5 in the aeration tank and the other support 6. And a main body portion 10 mounted on both supports 5 and 6 in an unfixed state.

The air supply pipe 2 consists of the main air supply pipe 3 and the air supply stand 4. The main air supply pipe 3 extends up and down from the outside of the aeration tank to the bottom, an upstream end is connected to a blower (not shown), and a flange 8 is provided at the downstream end. The air supply stand 4 has a protruding pipe 11 extending in the vertical direction and a curved pipe 12 extending from the side of the protruding pipe 11 and bent upward. The bent pipe 12 is provided with a flange 9, and the main air supply pipe 3 and the air supply stand 4 are tightly connected by fixing the flange 9 and the flange 8 of the main air supply pipe 3. . According to such a configuration, the downstream side of the air supply pipe 2 is bent upward by 180 degrees, and the downstream end is a protrusion 11 protruding upward.

The main body portion 10 is configured to be pulled up or down integrally at the time of installation or maintenance, and includes a submersible motor 13, a vane 15 mounted on a rotating shaft 14 of the submersible motor 13, and a vane wheel. (15) A main body casing 16 surrounding the periphery and an introduction pipe 17 for introducing the supply air from the air supply pipe 2 into the main body casing 16 are provided.

The submersible motor 13 includes a stator 19 fixed to an inner circumferential wall of the motor casing 18 and a rotor 20 arranged concentrically with the stator 19 inside the stator 19. ). On the inner circumferential surface of the rotor 20, a rotating shaft 14 extending downward is fixed. The rotary shaft 14 is supported by the upper shaft support 21 and the lower shaft support 22 so as to be free to rotate.

The lower part of the motor casing 18 is sealed by the oil casing 23. The rotating shaft 14 penetrates through the center portion of the oil casing 23. The submerged storage chamber 24 is formed above the central portion of the oil casing 23. The immersion storage chamber 24 is provided with a liquid level detector (not shown) to detect immersion into the motor. A mechanical seal bracket 26 is installed below the center of the oil casing 23, and a mechanical seal 31 is installed between the oil casing 23 and the mechanical seal bracket 26. The oil chamber 25 is partitioned by the oil casing 23 and the mechanical seal bracket 26.

The outer circumferential portion of the oil casing 23 spreads outward in the radial direction than the motor casing 18, and an air chamber 27 formed of an annular space surrounding the rotation shaft 14 is formed therein.

The introduction pipe 17 is a pipe for introducing air supplied from the air supply pipe 2 into the air chamber 27 and is formed as a U-shaped pipe. The introduction pipe 17 is installed in an inverted U shape so that both opening ends are opened downward. One end of the inlet tube 17 is formed to have a diameter larger than that of the protruding tube 11, and the opening end is a fitting portion 28 fitted to the protruding tube 11. The fitting portion 28 closes the end of the opening and is provided with an opening equal to the outer diameter of the protruding tube 11, and a packing 30 formed of nitrile rubber is provided around the opening. The packing 30 is for hermetically sealing between the fitting portion 28 and the protruding tube 11 when the fitting portion 28 of the introduction tube 17 is fitted to the protruding tube 11. One end of the inlet pipe 17 is fitted and fixed to the protruding pipe 11 so as to be covered with the tip of the protruding pipe 11 without using a fastener such as a bolt. On the other hand, at the other end of the inlet pipe 17, a flange 29 for connecting the inlet pipe 17 to the oil casing 23 is provided so that the inlet pipe 17 and the air chamber 27 communicate with each other. The other end of the introduction pipe 17 is fixed to the oil casing 23 via a fastener such as a bolt via the flange 29.

An impeller 15 is fastened to the tip of the rotation shaft 14. The vane 15 is comprised from the cylindrical hub 32 extended in parallel with the rotating shaft 14, and the some wing 33 which protruded in the outer peripheral surface of the hub 32. As shown in FIG. The blade 33 is installed to guide the liquid to be processed from below to above by rotation.

The partition wall 37 which extends to the hub 32 vicinity of the vane 15 is installed in the oil casing 23 lower part. Between the partition wall 37 and the hub 32, a slit-like gap is formed over the entire circumference, and the diffuser 38 is formed by this gap. As a result, the diffuser 38 supplies air only to the liquid to be processed downstream of the vane 15.

The main body casing 16 is installed so as to surround the periphery 15. The main body casing 16 is composed of a cylindrical suction casing 34 and a discharge casing 35 disposed above the suction casing 34. The suction casing 34 is formed to spread downward to smooth the flow of the liquid to be sucked from the lower side. A suction port is formed at the lower end of the suction casing 34. The discharge casing 35 is composed of an almost round annular upper plate 39 and a lower plate 40. The upper plate 39 and the lower plate 40 all extend downwardly inclined. As shown in FIG. 2, the partition member 41 is provided between the upper plate 39 and the lower plate 40 at predetermined intervals along the circumferential direction. In this embodiment, six partition members 41 are provided at equal intervals. Each partition member 41 is formed in a mountain shape, and is disposed so that the top portion faces inward. The discharge passage 42 is partitioned by the upper plate 39 and the lower plate 40 of the discharge casing 35 and the partition member 41. The discharge passage 42 is configured to discharge the mixed fluid of the liquid to be processed and the air flowing upwards downwardly while changing the flow direction.

On the side of the introduction pipe 17, a guide member 43 meshing with the main air supply pipe 3 is provided. The guide member 43 is formed of a plate-shaped member which is partially cut into a semi-circular shape approximately equal to the outer diameter of the main air supply pipe 3, and the cutting part is engaged with the main air supply pipe 3 to guide the main air supply pipe 3. The shanghai-dong of the main body 10 is guided. Accordingly, the air supply pipe 2 serves as a conduit for guiding the supply air to the main body 10 and also serves as a guide bar for guiding the main body 10. On the other hand, the guide member 44 of the same shape as the guide member 43 is provided in the position opposite to the guide member 43 of the discharge casing 35. This guide member 44 also guides the shanghai-dong of the main-body part 10 by engaging with the guide rod 7.

―Installation work of the aeration device―

As shown in FIG. 3, when the aeration apparatus 1 is installed, the main body portion 10 is connected to the chain (with the guide members 43 and 44 engaged with the main air supply pipe 3 and the guide rod 7, respectively). Hang on 45) and slowly descend. As a result, the main body 10 is guided to the main air supply pipe 3 and the guide bar 7, and is installed at an appropriate position on the supports 5 and 6 without being shaken as shown in FIG.

And the fitting part 28 of the introduction pipe 17 in the fall of the main-body part 10 is fitted to the front end of the protrusion pipe 11 so that it may be covered by the protrusion pipe 11, and it will be filled. As a result, the inlet pipe 17 is hermetically connected to the protruding pipe 11, and passes through the main air supply pipe 3, the curved pipe 12, the protruding pipe 11, and the inlet pipe 17 from the blower (not shown). The airtight air supply passage leading to the air chamber 27 is formed.

On the other hand, at the time of maintenance, the main body 10 and the guide rod 7 are guided, and the main body 10 is pulled up by the chain 45 and gradually lifted out of the aeration tank. At this time, the main body 10 is simply mounted on the supports 5 and 6, and the introduction pipe 17 is only inserted into the protruding pipe 11, so that no separation work or the like in the aeration tank is required. (10) can be lifted easily.

―Operation operation of the aeration device―

During operation of the aeration apparatus 1, the submersible motor 13 is driven to rotate the vanes 15 in accordance with the rotation of the rotary shaft 14. By the rotation of this vane 15, the to-be-processed liquid in a tank is sucked inward from the lower side of the suction casing 34. As shown in FIG. The aspirated to-be-processed liquid flows upward and passes the vane 15.

On the other hand, the air supplied from the blower (not shown) through the air supply pipe 2 and the introduction pipe 17 is introduced into the air chamber 27 and then passes through the vanes 15 through the diffuser 38. It is supplied to the downstream to-be-processed liquid immediately after it. At this time, since the diffuser 38 is formed in a ring shape and a slit shape, air is supplied uniformly and in a film state over the entire circumference with respect to the liquid to be treated. Since the downstream processing liquid immediately after passing through the impeller 15 is stirred by the impeller 15, the air supplied is refined and becomes a large number of micro bubbles, and is mixed into the liquid to be treated.

At this time, since the discharge passage 42 is formed inclined downward as shown in Fig. 5, the flow direction of the mixed fluid of the bubbles and the to-be-processed liquid is bent rapidly in the downward direction inclined from the upward direction. For this reason, a large centrifugal force acts on the mixed fluid (particularly, the liquid to be treated included in the mixed fluid), and the liquid to be processed easily flows above the discharge passage 42. As a result, bubbles which are likely to collect on the upper part of the discharge passage 42 are vigorously stirred by the liquid to be treated. Therefore, bubbles and the processing liquid are mixed with each other and the oxygen dissolution efficiency (oxygen transfer efficiency) to the processing liquid is improved.

-Effect of Example

In this embodiment, since the diffuser 38 is formed on the downstream side of the vane 15, the fluid passing through the vane 15 becomes only the liquid to be treated so that the supply air passes through the vane 15. There is no work. Therefore, even if the supply amount of air increases, the flow volume of the to-be-processed liquid does not decrease, and the fall of the oxygen transfer efficiency by the liquid quantity of the to-be-processed liquid can be prevented.

Since the discharge passage 42 is inclined downward, the flow direction of the mixed fluid rapidly changes from the upward direction to the downward downward direction. For this reason, the centrifugal force acts on the mixed fluid, and the bubbles which are likely to collect on the discharge passage 42 are dispersed by the processing liquid, and the processing liquid and the air are severely mixed. Therefore, the dissolution efficiency of oxygen to the to-be-processed liquid of the discharge passage 42 can be improved.

In this way, even if the air supply amount is increased, the flow rate of the liquid to be processed does not decrease, and further, the oxygen supply efficiency in the discharge passage 42 is improved, so that the air supply amount can be increased compared with the conventional one. Therefore, it is possible to improve the oxygen transfer efficiency than the conventional.

In addition, since the guide members 43 and 44 are installed in the main body 10 and the air supply pipe 2 and the guide bar 7 are guided to guide the shanghai movement of the main body 10, the main body 10 is provided. It is possible to position and install the main body 10 in a proper place only by suspending the chain 45. And when pulling up the main-body part 10, the main-body part 10 does not shake, and can raise a main-body part 10 easily.

Further, a protruding tube 11 which protrudes upward from the downstream side of the air supply pipe 2 is used, and an introduction tube 17 for introducing air supplied from the protruding tube 11 into the air chamber 27 is provided with a protruding tube ( 11, the introduction pipe 17 can be automatically connected to the air supply pipe 2 only by pulling down the main body 10. As shown in FIG. Moreover, the connection of the inlet pipe 17 and the air supply pipe 2 can be automatically canceled only by pulling up the main-body part 10. FIG. Therefore, no fastener such as a bolt for connecting the main body 10 and the air supply pipe 2 is required, and the installation and detachment work of the main body 10 becomes easy. Therefore, maintenance work is easy.

―Modification example―

In the above embodiment, the guide member 43 engaged with the main air supply pipe 3 of the air supply pipe 2 and the guide member 44 engaged with the guide rod 7 as guide means for guiding the main body portion 10. ), But only one of the guide members 43 and 44 may be provided. In addition, the mounting positions of the guide members 43 and 44 are not limited to the position of the said embodiment, According to the shape of the main-body part 10, you may change suitably. The guide member 43 is not limited to being engaged with the main air supply pipe 3, but may be formed to engage with the air supply stand 4. For example, as shown in FIG. 6, you may be provided with the guide member 43a or 43b which engages with the protrusion pipe 11 of the air supply stand 4. As shown in FIG. Moreover, you may provide both the guide member 43 and the guide member 43a, 43b.

As shown in FIG. 7, the air supply pipe 2 and the main body part 10 may be directly connected, and the support stand 50 may be provided in the lower part of the main body casing 16. As shown in FIG. The support stand 50 is provided in plurality at predetermined intervals along the circumferential direction. The support 50 is formed at an appropriate height so as to secure sufficient space for sucking the liquid to be processed from below. Even if it is such a form, since the diffuser 38 is formed downstream of the vane 15, the fall of the oxygen transfer efficiency by the flow volume reduction of the to-be-processed liquid can be prevented. In addition, the discharge passage 42 discharges the mixed fluid of the processing liquid and air while changing the flow direction thereof, so that the oxygen dissolution efficiency is improved.

According to the present invention as described above, since the diffuser is formed on the downstream side of the impeller, the amount of the liquid to be sucked by the impeller can always be sufficiently secured, and oxygen due to the decrease in the amount of the liquid to be treated can be obtained. The fall of the moving efficiency can be prevented.

Since the discharge passage is formed so as to change the flow direction of the mixed fluid from the upward direction to the downward direction, the air and the liquid to be treated can be mixed strongly in the discharge passage. Therefore, the oxygen transfer efficiency can be improved.

By forming an annular air chamber surrounding the rotating shaft of the submersible motor, and forming the diffuser by the slit-shaped gap between the lower edge of the partition wall of the air chamber and the vane, the liquid to be processed downstream of the vane Air can be supplied efficiently to the.

By providing a support angle of an appropriate height in the lower portion of the casing, the casing can be stably supported, and suction of the processing liquid from the lower side becomes easier.

Since the downstream side of the air supply pipe is bent upward and the inlet pipe is attached to and detached from the downstream end of the air supply pipe along the shanghai east side of the main body, manual connection work for connecting the air supply pipe and the main body can be omitted. You can do it easily.

By installing a guide member which engages with one or both of the air supply pipe and the guide rod in the main body, it is easy to move the main body in a simple manner, and positioning can be performed at a predetermined mounting position by simply suspending the main body. have. This makes maintenance easier.

The downstream end of the air supply pipe is a protrusion projecting upward, and the introduction pipe is formed so as to be fitted to the protrusion, so that the introduction pipe can be inserted into the air supply pipe simply by suspending and lowering the main body part, and only pulling up the main body part. This allows the introduction tube to be separated from the air supply pipe. Therefore, the main body part and the air supply pipe can be automatically connected or disconnected according to the shanghai-dong of the main body part, and maintenance becomes easier.

Claims (7)

A main body having an underwater motor, a vane mounted on a rotating shaft of the submarine motor, a casing surrounding the vane, An aeration device having an air supply pipe for supplying air to the main body, The casing is provided with a suction port for sucking the liquid to be treated from below, and a discharge passage for discharging the mixed liquid of the liquid to be processed and the air flowing upward in the casing downwardly while changing its flow direction. An aeration device for supplying air from the air supply pipe to the liquid to be treated is provided on the downstream side of the van. The method of claim 1, Between the submersible motor in the main body and a vane, an annular air chamber is formed so as to enclose the rotational axis of the submersible motor, The air supply pipe is formed to introduce air into the air chamber, The air diffuser is formed by a slit gap between the lower edge of the air compartment partition wall and a vane. The method according to claim 1 or 2, The casing is provided with a support having an appropriate height in the lower portion. A main body having an underwater motor, a vane mounted on a rotating shaft of the submarine motor, a casing surrounding the vane, An aeration device provided with a supply pipe extending in the vertical direction, provided on the side of the main body, The downstream side of the air supply pipe is bent upwards, The main body portion is provided with an introduction pipe which is attached to and detached from the downstream end of the air supply pipe along the shanghai east of the main body, and introduces air supplied from the air supply pipe into the casing. The casing is provided with a suction port for sucking the liquid to be treated from below, and a discharge passage for discharging the mixed fluid of the liquid to be processed and the air flowing upward in the casing downwardly while changing its flow direction. An aeration apparatus for supplying air from the introduction pipe to the liquid to be treated is formed on the downstream side of the van. The method of claim 4, wherein The main body portion is guided to the air supply pipe, or a guide bar separate from the air supply pipe as a guide, or both the air supply pipe and the guide rod as a guide to guide the main body part. And a guide member engaged with one or both of them. The method according to claim 4 or 5, The downstream end of the inlet duct forms an overhanging protrusion, The inlet pipe is connected to this air supply pipe by being fitted to the protrusion part of the said air supply pipe by suspension of a main-body part, The aeration apparatus characterized by the above-mentioned. The method according to claim 4 or 5, Between the underwater motor and the vane in the main body portion, an annular air chamber is formed so as to surround the rotational axis of the underwater motor. The introduction pipe is formed to introduce air from the air supply pipe into the air chamber, The air diffuser is formed by a slit gap between the lower edge of the partition wall of the air chamber and the vane.