Bubble supply facility

Abstract

To provide a bubble supply facility that suppresses consumption of a power amount.SOLUTION: A bubble supply facility 1 according to the present invention includes: an aeration tank 2 that stores liquid; a stirring device 3 that stirs the liquid stored in the aeration tank 2; a supply port 30 that supplies fine bubble liquid into the aeration tank 2; a liquid feeding device 5 that includes a pump 51 for feeding the fine bubble liquid to the supply port 30; and a control device 7 that adjusts the supply amount of the fine bubble liquid supplied from the supply port 30 by intermittently driving the pump 51.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a bubble supply facility for supplying bubbles to a stored liquid.

Background Art

[0002] In sewage treatment plants that treat sewage such as sewage and rainwater, aerobic biological treatment is performed to remove nitrogen, phosphorus, etc. from the sewage. Aerobic biological treatment is performed in a bubble supply facility equipped with an aeration tank for storing sewage. In this bubble supply facility, an air diffuser is installed at the bottom of the aeration tank, and air is ejected from the air diffuser into the aeration tank as fine bubbles, and the liquid is stirred by the upward force of the bubbles, so that oxygen is dissolved in the liquid stored in the aeration tank. In addition to sewage treatment plants, for example, in fish farms that cultivate aquatic organisms such as fish, a bubble supply facility equipped with an air diffuser and ejecting bubbles from the air diffuser to stir the water is also used to dissolve oxygen necessary for aquatic organisms in water or seawater (see, for example, Patent Document 1, etc.).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the bubble supply facility described in this Patent Document 1, air must be sent against the water pressure up to the air diffuser at the bottom of the tank, and the sent air must be ejected as bubbles from a plurality of small holes in the air diffuser. In addition, among the oxygen contained in the bubbles ejected from the air diffuser, the oxygen dissolved in the sewage or water usually accounts for only about 10 to 30%. Therefore, it is necessary to eject a large amount of bubbles from the air diffuser. In addition, in order to stir the sewage or water by the upward force of the bubbles ejected from the air diffuser, it is necessary to eject more bubbles than necessary even when the supply of bubbles is not required due to a high dissolved oxygen concentration (DO value). Furthermore, in order to prevent clogging of the bubble ejection ports of the air diffuser, bubbles are constantly ejected to remove sludge, dust, etc. near the bubble ejection ports. For these reasons, a large pump for sending a large amount of air to the bottom of the tank with a strong force is required, and there is a problem that a large amount of power is consumed to drive the large pump continuously for a long time.

[0005] In view of the above circumstances, an object of the present invention is to provide a bubble supply facility that suppresses power consumption.

Means for Solving the Problems

[0006] The bubble supply facility of the present invention for solving the above object includes a storage tank for storing a liquid containing viscous substances and solids, a stirring device for stirring the liquid stored in the storage tank, a supply port for supplying a fine bubble liquid to the storage tank, a liquid feeding device having a pump for sending out the fine bubble liquid to the supply port, and a supply amount adjusting means for adjusting the supply amount of the fine bubble liquid supplied from the supply port by intermittently driving the pump.

[0007] In this bubble supply facility, the pump may have a constant suction volume.

[0008] Also, in this bubble supply facility, the stirring device has a shaft that rotates around an axis, The supply ports may be provided in plurality at intervals in the extending direction of the shaft.

Advantages of the Invention

[0009] According to the present invention, it is possible to provide a bubble supply facility that suppresses power consumption.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The bubble supply facility used in the description of an embodiment of the present invention is disposed in a sewage treatment plant and is a bubble supply facility that performs aerobic biological treatment in order to remove nitrogen, phosphorus, etc. from sewage.

[0012] FIG. 1 is a schematic plan view of a bubble supply facility corresponding to an embodiment of the present invention.

[0013] As shown in FIG. 1, the bubble supply facility 1 of the present embodiment includes an aeration tank 2, a stirring device 3, a liquid feeding device 5, a concentration sensor 6, and a control device 7. This bubble supply facility 1 is a sewage treatment facility that performs biological treatment on sewage from which contaminants such as sand have been removed in a sewage treatment plant. Sewage such as sewage and rainwater treated in a grit chamber and a primary sedimentation tank (not shown) flows into the aeration tank 2. The aeration tank 2 is a tank having a rectangular shape in plan view that receives and stores the inflowing sewage. This aeration tank 2 corresponds to an example of a storage tank, and the sewage received by the aeration tank 2 corresponds to an example of a liquid. In the aeration tank 2, activated sludge containing a large amount of aerobic microorganisms and a fine bubble liquid are supplied, and aerobic biological treatment is performed by stirring these with the sewage. The sewage subjected to biological treatment in the aeration tank 2 is sent to a final sedimentation tank (not shown). Note that an anaerobic tank that performs anaerobic biological treatment may be provided upstream of the aeration tank 2, or a plurality of anaerobic tanks and a plurality of aeration tanks 2 may be alternately arranged. The stirring device 3 is disposed in the central portion of the aeration tank 2 in plan view.

[0014] FIG. 2 is a cross-sectional view taken along line A-A of the bubble supply facility shown in FIG. 1.

[0015] As shown in FIG. 2, the stirring device 3 is a propeller-type water flow generating device including two blades 31, 31, a shaft 32, and a motor 33. Note that, as the stirring device 3, one having three or more blades 31 may be used. The blades 31 are disposed at a height position approximately in the middle between the water surface WL of the sewage stored in the aeration tank 2 and the bottom surface 2a of the aeration tank 2 within the aeration tank 2. The water surface WL may vary somewhat depending on the amount of sewage flowing into the aeration tank 2. The blades 31 are disposed at a position always submerged in water regardless of the fluctuation of the water level. The blades 31 rotate when the motor 33 rotates. The motor 33 is controlled by the control device 7. The rotation speed of the blades 31 is appropriately set in the range of 10 to 60 RPM according to the volume and shape of the aeration tank 2 and the like. When the blades 31 rotate, a downward sewage flow is generated in the vicinity of the blades 31. Then, due to the rotation of the blades 31, a circulation flow that goes downward in the central portion of the aeration tank 2 in plan view and upward in the peripheral portion of the aeration tank 2 in plan view is formed. The circulation flow circulates in the aeration tank 2 at a flow velocity of 0.1 m / sec or more. The sewage stored in the aeration tank 2, the activated sludge supplied to the aeration tank 2, and the fine bubble liquid supplied to the aeration tank 2 are stirred by the circulation flow. Note that the blades 31 may be rotated in the reverse direction to form an upward flow in the vicinity of the blades 31, or the blades 31 may be directed laterally to form a lateral flow in the vicinity of the blades 31.

[0016] The shaft 32 is a tube with openings at its upper and lower ends, and a shaft internal flow path 32a connecting the openings at the upper and lower ends is formed inside. The opening at the lower end of this shaft 32 serves as the supply port 30 for the fine bubble liquid. The supply port 30 opens downward and discharges the fine bubble liquid downward. In FIG. 2, the discharge direction of the fine bubble liquid is indicated by a straight arrow. The shaft 32 is rotatably supported by the aeration tank 2 by a bearing (not shown). A rotary joint 321 is connected to the upper end portion of the shaft 32. A boss portion 311 is formed on the rotation center side portion of the blade 31, and by this boss portion 311, the blade 31 is fixed to the lower end portion of the shaft 32. The blade 31 and the shaft 32 in this embodiment correspond to an example of a rotating part and also correspond to an example of an operating part. In this embodiment, the height position of the lower end of the blade 31 and the height position of the lower end of the boss portion 311 are the same. However, the height position of the lower end of the blade 31 and the height position of the lower end of the boss portion 311 may be different.

[0017] A driven pulley 322 is fixed to the shaft 32 slightly below the rotary joint 321. Also, a drive pulley 332 is fixed to the lower end of the output shaft 331 of the motor 33. And the driven pulley 322 and the drive pulley 332 are connected by a V-belt 333. By driving the motor 33, the shaft 32 rotates at approximately the same rotational speed as the motor 33. The motor 33 and the rotary joint 321 are fixed by a fixture (not shown) above the aeration tank 2.

[0018] The liquid supply device 5 includes a liquid tank 50, a pump 51, a bubble liquid delivery pipe 52, and a bubble liquid generation device 53. The pump 51 is disposed within the liquid tank 50 and sucks up and delivers the water stored in the liquid tank 50. The liquid tank 50 is replenished with water sucked up from a final sedimentation tank (not shown), thereby maintaining a predetermined amount of water at all times. Note that tap water may be supplied to the liquid tank 50. The bubble liquid delivery pipe 52 is a pipe having one end connected to the pump 51 and the other end connected to the rotary joint 321. In FIGS. 1 and 2, the bubble liquid delivery pipe 52 is shown in a simplified manner with only solid lines. The water sucked up by the pump 51 is sent out to the supply port 30 through the bubble liquid delivery pipe 52, the rotary joint 321, and the shaft internal flow path 32a, and is discharged from the supply port 30 into the aeration tank 2. As described above, the shaft 32 rotates by driving the motor 33, but since the bubble liquid delivery pipe 52 is connected to the shaft 32 via the rotary joint 321, it does not rotate regardless of the rotation of the shaft 32.

[0019] The bubble liquid generating device 53 is installed in the middle of the bubble liquid delivery pipe 52. The bubble liquid generating device 53 is a device that generates a fine bubble liquid by a known swirling liquid flow method (see, for example, Patent No. 6169749, etc.). However, a fine bubble liquid may also be generated by other methods such as a pressurized dissolution method. The fine bubble liquid is a fine bubble-containing liquid containing fine bubbles of 100 μm or less. Also, the fine bubble liquid may be a liquid containing microbubbles that are bubbles with a diameter greater than 1 μm and 100 μm or less, or a liquid containing ultrafine bubbles that are bubbles with a diameter of 1 μm or less. Further, the fine bubble liquid may be a liquid containing both microbubbles and ultrafine bubbles. The water sucked up by the pump 51 becomes a fine bubble liquid by the bubble liquid generating device 53 and is supplied from the supply port 30 to the aeration tank 2. The pump 51 is driven intermittently according to a command from the control device 7. The control device 7 adjusts the supply amount of the fine bubble liquid supplied from the supply port 30 to the aeration tank 2 by driving the pump 51 intermittently. This control device 7 corresponds to an example of a supply amount adjusting means. In this embodiment, the pump 51 has a constant water suction amount, but a pump 51 capable of adjusting the amount of water sucked up may be used, and its suction amount may be controlled by the control device 7.

[0020] The concentration sensor 6 is disposed in the aeration tank 2. This concentration sensor 6 is a sensor that detects the dissolved oxygen concentration contained in the sewage stored in the aeration tank 2. The concentration sensor 6 is disposed at a height position approximately in the middle between the water surface WL of the sewage stored in the aeration tank 2 and the tank bottom surface 2a of the aeration tank 2, and is always submerged in the water regardless of the fluctuation of the water surface WL. The dissolved oxygen concentration detected by the concentration sensor 6 is input to the control device 7. In FIG. 2, the signal line connecting the concentration sensor 6 and the control device 7, the control line connecting the control device 7 and the motor 33, and the control line connecting the control device 7 and the pump 51 are shown by broken lines.

[0021] Next, the operation of this bubble supply facility 1 will be described. Except for special cases such as maintenance, the control device 7 constantly drives the motor 33 of the stirring device 3 to rotate the blades 31 and the shaft 32. Also, the control device 7 controls the driving of the pump 51 according to the dissolved oxygen concentration detected by the concentration sensor 6. Note that the control device 7 may be incorporated in the pump 51 and only control the driving of the pump 51. In this case, another control device may be provided for the motor 33. Additionally, the control device 7 may be a centralized control device that controls not only the devices provided in the bubble supply facility 1 but also the devices provided in other facilities installed in the sewage treatment plant. When the dissolved oxygen concentration input from the concentration sensor 6 to the control device 7 is higher than 2.0 mg / L, the control device 7 stops the pump 51 to make the supply amount of the fine bubble liquid to the aeration tank 2 zero. When the dissolved oxygen concentration is 2.0 mg / L or less, the control device 7 drives the pump 51 so that the dissolved oxygen concentration approaches 2.0 mg / L. Note that the target value of the dissolved oxygen concentration may be appropriately set according to the size of the aeration tank 2, the amount of activated sludge supplied to the aeration tank 2, and the concentrations of nitrogen and phosphorus contained in the sewage. Also, when using a pump 51 with an adjustable suction amount, the control device 7 may adjust the suction amount of the pump 51 according to the dissolved oxygen concentration.

[0022] According to this embodiment, since the pump 51 is controlled according to the dissolved oxygen concentration to adjust the supply amount of the fine bubble liquid to the aeration tank 2, it is possible to secure the amount of oxygen necessary for aerobic biological treatment in the sewage. Further, since the fine bubble liquid containing fine bubbles which are floating bubbles is supplied, oxygen can be efficiently dissolved in the sewage. As a result, since the dissolved oxygen concentration is likely to increase, the pump 51 can be intermittently operated to adjust the supply amount of the fine bubble liquid. Then, when the dissolved oxygen concentration in the sewage stored in the aeration tank 2 exceeds the required concentration value, the pump 51 is stopped, so that the power consumption of the pump 51 can be suppressed. When a pump 51 capable of adjusting the suction amount is used, when the dissolved oxygen concentration is close to the target value, the suction amount of the pump 51 may be decreased, and when it exceeds the target value, the pump 51 may be stopped or the suction amount may be made extremely small. Further, since the supply port 30 for the fine bubble liquid is formed in the rotating shaft 32, it is difficult for sludge or the like to remain at the supply port 30, and as a result, clogging of the supply port 30 can be suppressed. Furthermore, since the supply port 30 opens downward, it is possible to prevent the supply port 30 from being blocked and clogged by viscous substances or solids such as sludge that settle from above. In addition, since the supply port 30 is arranged in the vicinity of the blade 31, the stirring performance of the fine bubble liquid is enhanced. Furthermore, when a diffuser is used, it is necessary to make the ejection port small in order to generate fine bubbles, but since the fine bubble liquid is supplied, the supply port 30 can be enlarged to suppress clogging. Even if the supply port 30 is clogged, by sending the fine bubble liquid to the supply port 30, it is easy to extrude the clogging substances such as sludge that cause the clogging of the fine bubble liquid. Also, since the surface area to volume ratio of the fine bubbles is larger than that of general bubbles, aerobic biological treatment can be efficiently performed. As a result, even if each component of the bubble supply facility 1 such as the aeration tank 2 is miniaturized, a high biological treatment capacity can be obtained. By miniaturizing, the power for driving each component can be suppressed. Also, by miniaturizing, the land required for constructing the bubble supply facility 1 can be reduced.

[0023] Next, a modification of this embodiment will be described. In the following description, components with the same names as those of the components described so far may be described with the same reference numerals as those used so far, and redundant descriptions may be omitted.

[0024] FIG. 3(a) is a plan view showing a first modification of the stirring device shown in FIGS. 1 and 2, and FIG. 3(b) is a front view of the stirring device shown in FIG. 3(a). In FIGS. 3(a) and 3(b), the motor 33 is not shown.

[0025] As shown in FIG. 3(a), the stirring device 3 of this first modification is different from the stirring device 3 shown in FIGS. 1 and 2 in that a supply port 30 is provided in the blade 31. The supply port 30 is formed at the tip portion of each of the two blades 31, 31. This supply port 30 is formed on the side surface opposite to the rotation direction of the blade 31 and at the central portion in the height direction of the blade 31. In FIG. 3(a), the rotation direction of the blade 31 is indicated by a curved arrow. That is, the blade 31 rotates clockwise in FIG. 3(a). As shown in FIG. 3(b), inside the blade 31, a blade internal flow path 31a connected to the shaft internal flow path 32a and continuous to the supply port 30 is formed. The fine bubble liquid sucked up by the pump 51 (see FIG. 2) and sent out to the shaft internal flow path 32a is discharged into the aeration tank 2 (see FIG. 2) from the supply port 30 through the blade internal flow path 31a. In FIGS. 3(a) and 3(b), the shaft internal flow path 32a and the blade internal flow path 31a are each shown by a thin dashed line. Also, as shown in FIG. 3(b), the lower end of the shaft 32 is closed.

[0026] In the stirring device 3 of this first modification example, the supply port 30 is open in a direction inclined obliquely upward along the side surface shape of the blade 31 at the tip portion of the blade 31. As shown in Fig. 3(a), this supply port 30 discharges the fine bubble liquid in the direction opposite to the rotation direction of the blade 31. In Fig. 3(a), the discharge direction of the fine bubble liquid is indicated by a straight arrow. In the stirring device 3 of this modification example, since the supply port 30 is directed in the direction opposite to the rotation direction of the blade 31, a force is exerted on the fine bubble liquid in the blade internal flow path 31a from the supply port 30 as the blade 31 rotates. Also, due to the centrifugal force caused by the rotation of the blade 31, a force acting toward the supply port 30 is exerted on the fine bubble liquid in the blade internal flow path 31a. Due to these forces, even if the suction force of the water in the pump 51 is small, the fine bubble liquid can be discharged from the supply port. Therefore, the power of the pump 51 can be further reduced. Also, since the supply port 30 is formed on the side surface opposite to the rotation direction of the blade 31, it is difficult for sludge in the sewage to enter the supply port 30 when the blade 31 is rotating.

[0027] Next, a second modification example of the stirring device 3 will be described. In the description of this second modification example, mainly the differences from the first modification example will be described, and the descriptions overlapping with the first modification example may be omitted.

[0028] Fig. 4(a) is a plan view showing a second modification example of the stirring device shown in Figs. 1 and 2, and Fig. 4(b) is a front view of the stirring device shown in Fig. 4(a). Also in Figs. 4(a) and 4(b), the motor 33 is not shown.

[0029] As shown in FIGS. 4(a) and 4(b), the stirring device 3 of this second modification is different from the stirring device 3 shown in FIG. 3 in that a plurality of supply ports 30, 30, ··· are provided in the blade 31. Similar to the first modification, in this second modification, the blade 31 rotates clockwise in FIG. 4(a). The supply ports 30 are formed on the side surface opposite to the rotation direction of the blade 31, at the central portion in the height direction of the blade 31, five for each blade 31. Note that the number of the supply ports 30 may be more than five or less than five. The supply ports 30 open in a direction inclined obliquely upward along the side surface shape of the blade 31. And in the blade internal flow path 31a formed in the blade 31 as shown in FIG. 4(a), a plurality of blade internal branch flow paths 31b, 31b ··· that branch into the respective supply ports 30, 30, ··· are formed.

[0030] The fine bubble liquid sucked up by the pump 51 (see FIG. 2) and sent out to the shaft internal flow path 32a is discharged into the aeration tank 2 (see FIG. 2) from each supply port 30 through the blade internal flow path 31a and the blade internal branch flow paths 31b.

[0031] Each supply port 30 discharges the fine bubble liquid in the direction opposite to the rotation direction of the blade 31. In FIG. 4(a), the discharge direction of the fine bubble liquid is indicated by a straight arrow. Also in this second modification, since the supply ports 30 face the direction opposite to the rotation direction of the blade 31, a force is exerted on the fine bubble liquid in the blade internal flow path 31a from the supply ports 30 as the blade 31 rotates. Also, due to the centrifugal force caused by the rotation of the blade 31, a force acts on the fine bubble liquid in the blade internal flow path 31a toward the supply ports 30. Furthermore, since there are a plurality of supply ports 30 for each blade 31, the resistance during the discharge of the fine bubble liquid is small. Due to these factors, even if the suction force of water in the pump 51 is small, the fine bubble liquid can be discharged from the supply ports. Therefore, the power of the pump 51 can be further reduced. Also, since each supply port 30 is formed on the side surface opposite to the rotation direction of the blade 31, when the blade 31 is rotating, it is difficult for sludge in the sewage, etc. to enter the supply ports 30.

[0032] Next, a third modification example of the stirring device 3 will be described. In the description of this third modification example, mainly the differences from the second modification example will be described, and the descriptions overlapping with the second modification example may be omitted.

[0033] FIG. 5(a) is a plan view showing a third modification example of the stirring device shown in FIGS. 1 and 2, and FIG. 5(b) is a front view of the stirring device shown in FIG. 5(a). Also in FIGS. 5(a) and 5(b), the motor 33 is not shown.

[0034] As shown in FIGS. 5(a) and 5(b), the stirring device 3 of this third modification example is different from the stirring device 3 shown in FIG. 4 in that a plurality of supply ports 30, 30,... are provided at the lower end portion of the blade 31. Similar to the second modification example, in this third modification example, the blade 31 rotates clockwise in FIG. 5(a). The supply port 30 is on the side surface opposite to the rotation direction of the blade 31, and five supply ports are formed for each blade 31 at the lower end portion of the blade 31. Note that the number of the supply ports 30 may be more than five or less than five. The lower end portion of the blade 31 is formed in a vertical plane, and the plurality of supply ports 30, 30,... open horizontally and laterally.

[0035] Each supply port 30 discharges the fine bubble liquid in a direction opposite to the rotation direction of the blade 31. In FIG. 5(a), the discharge direction of the fine bubble liquid is indicated by a straight arrow. Also in this third modification, since the supply port 30 faces in a direction opposite to the rotation direction of the blade 31, as the blade 31 rotates, a force is exerted on the fine bubble liquid in the blade internal flow path 31a and released from the supply port 30. Further, due to the centrifugal force caused by the rotation of the blade 31, a force acting toward the supply port 30 is also exerted on the fine bubble liquid in the blade internal flow path 31a. Furthermore, since there are a plurality of supply ports 30 for each blade 31, the resistance during the discharge of the fine bubble liquid is small. Due to these factors, even if the suction force of water in the pump 51 is small, the fine bubble liquid can be discharged from the supply port. Therefore, the power of the pump 51 can be further reduced. Also, since each supply port 30 is formed on the side surface opposite to the rotation direction of the blade 31, when the blade 31 is rotating, it is difficult for sludge in the sewage to enter the supply port 30. Furthermore, in the stirring device 3 of the third modification, since the supply port 30 is opened horizontally, even if viscous substances or solids such as sludge settle from above, these viscous substances or solids do not enter the supply port 30. This can further reduce the risk of the supply port 30 being blocked.

[0036] Subsequently, a fourth modification of the stirring device 3 will be described. In the description of this fourth modification, the differences from the stirring device 3 shown in FIGS. 1 and 2 will be described, and descriptions overlapping with the description of the stirring device 3 shown in FIGS. 1 and 2 may be omitted.

[0037] FIG. 6(a) is a front view showing a fourth modification of the stirring device shown in FIGS. 1 and 2, and FIG. 6(b) is a cross-sectional view taken along line B - B of the stirring device shown in FIG. 6(a). Also in FIG. 6(a), the motor 33 is not shown.

[0038] As shown in Fig. 6(a), the stirring device 3 of this fourth modification is different from the stirring device 3 shown in Figs. 1 and 2 in that two supply pipes 34, 34 are fixed to the shaft 32, and a plurality of supply ports 30, 30, ··· are provided in each of the supply pipes 34. In this modification, the blades 31, the shaft 32, and the two supply pipes 34, 34 correspond to an example of the rotating part. Note that also in this fourth modification, the blades 31, the shaft 32, and the two supply pipes 34, 34 rotate clockwise in Fig. 6(b). As shown in Fig. 6(a), the shaft 32 has a shaft internal flow path 32a formed only in the upper part. Also, inside the supply pipe 34, a supply pipe internal flow path 34a with its upper and lower ends closed is formed. And at the upper part of the shaft 32 and the upper part of the supply pipe 34, a connecting part 32b for connecting and fixing the shaft 32 and the supply pipe 34 is formed, and a through hole connecting the shaft internal flow path 32a and the supply pipe internal flow path 34a is formed inside the connecting part 32b. The supply ports 30 are opened four in number for each supply pipe 34 toward the outside of the supply pipe 34 in the radial direction of rotation. Note that the number of the supply ports 30 may be more than four or less than four. These supply ports 30, 30 ··· are each continuous with the supply pipe internal flow path 34a. The fine bubble liquid flowing into the shaft internal flow path 32a through the rotary joint 321 is discharged from each supply port 30 in the radial direction of rotation of the shaft 32. In Fig. 6(a), the discharge direction of the fine bubble liquid is indicated by a straight arrow.

[0039] In the stirring device 3 of this fourth modification, since the supply port 30 faces the radial direction of the rotation radius of the supply pipe 34, as the supply pipe 34 rotates, a force that is discharged from the supply port 30 by centrifugal force acts on the fine bubble liquid in the supply pipe internal flow path 34a. Further, since there are a plurality of supply ports 30 for each supply pipe 34, the resistance during the discharge of the fine bubble liquid is small. Due to these factors, even if the suction force of the fine bubble liquid in the pump 51 is small, the fine bubble liquid can be discharged from the supply port. Therefore, the power of the pump 51 can be reduced. Also, since each supply port 30 is formed in the supply pipe 34 that moves by rotation, when the blades 31 are rotating, it is difficult for sludge and the like in the sewage to enter the supply port 30. Furthermore, since the supply port 30 opens laterally, even if viscous substances and solids such as sludge settle from above, those viscous substances and solids do not enter the supply port 30. Thereby, the risk of the supply port 30 being blocked can be further reduced.

[0040] Next, a fifth modification of the stirring device 3 will be described. In the description of this fifth modification, mainly the differences from the fourth modification will be described, and the descriptions overlapping with the fourth modification may be omitted.

[0041] FIG. 7(a) is a plan view showing a fifth modification of the stirring device shown in FIGS. 1 and 2, and FIG. 7(b) is a cross-sectional view taken along the line C-C of the stirring device shown in FIG. 7(a). Also in this FIG. 7(a), the motor 33 is not shown.

[0042] As shown in FIG. 7(a), the stirring device 3 of this fifth modification is different from the stirring device 3 of the fourth modification in that only one supply pipe 34 is fixed to the shaft 32. Also in this fifth modification, the blades 31, the shaft 32, and the supply pipe 34 rotate clockwise as in FIG. 6(b). As shown in FIG. 7(a), all of the fine bubble liquid that has flowed into the shaft internal flow path 32a via the rotary joint 321 flows into the supply pipe internal flow path 34a in one supply pipe 34, and is discharged from the four supply ports 30, 30,... formed in the supply pipe 34 in the radial direction of the rotation radius of the shaft 32. In FIG. 7(a), the discharge direction of the fine bubble liquid is indicated by a straight arrow.

[0043] In the stirring device 3 of this fifth modification, in addition to having the same effects as the stirring device 3 of the fourth modification, since there is only one supply pipe 34, the stirring device 3 can be configured at low cost. However, in the fifth modification, since there is only one supply pipe 34, the center of gravity is greatly eccentric with respect to the rotation axes of the blades 31, the shaft 32, and the supply pipe 34, and vibrations will occur when the blades 31, the shaft 32, and the supply pipe 34 are rotated at high speed. For this reason, when rotating the blades 31, the shaft 32, and the supply pipe 34 at high speed, it is preferable to use the stirring device 3 of the fourth modification rather than the stirring device 3 of the fifth modification.

[0044] From the bubble supply facility 1 of the embodiments and modifications described above, a storage tank for storing a liquid, a stirring device for stirring the liquid stored in the storage tank, and a supply port for supplying a fine bubble liquid to the storage tank, it is possible to derive the concept of a bubble supply facility characterized in that the supply port is provided in an operating part that operates.

[0045] Here, the operating part may be something that rotates or something that moves linearly. By providing the supply port in the operating part, it is possible to prevent the supply port from becoming clogged.

[0046] Next, the bubble supply facility 1 of the second embodiment will be described.

[0047] FIG. 8 is a cross-sectional view similar to FIG. 2 showing the bubble supply facility of the second embodiment.

[0048] As shown in FIG. 8, the bubble supply facility 1 of the second embodiment is different from the previous bubble supply facility 1 shown in FIGS. 1 and 2 in that the stirring device 3 is not provided with a rotary joint 321, a driven pulley 322, a driving pulley 332, and a V-belt 333, and the fine bubble liquid is directly supplied from the liquid feeding device 5 to the aeration tank 2. The shaft 32 of the stirring device 3 is composed of a solid shaft. This shaft 32 is connected to the output shaft 331 of the motor 33 by a shaft coupling 334 and rotates in synchronization with the rotation of the motor 33. Note that the output shaft 331 of the motor 33 may be formed to be long and used as the shaft 32.

[0049] The water sucked up from the liquid tank 50 by the pump 51 of the liquid feeding device 5 is generated as a fine bubble liquid with fine bubbles added by the bubble liquid generating device 53. Then, the generated fine bubble liquid is discharged from the tip of the bubble liquid delivery pipe 52 into the aeration tank 2. In this embodiment, the opening at the tip of the bubble liquid delivery pipe 52 serves as the supply port 30. The tip side portion of the bubble liquid delivery pipe 52 extends vertically below the water surface WL of the sewage stored in the aeration tank 2. The fine bubble liquid sucked up by the pump 51 is discharged downward from the supply port 30 disposed in the aeration tank 2 into the stored sewage. In FIG. 8, the discharge direction of the fine bubble liquid is indicated by a straight arrow.

[0050] Also in the bubble supply facility 1 of this second embodiment, the control device 7 controls the pump 51 to adjust the supply amount of the fine bubble liquid to the aeration tank 2 according to the dissolved oxygen concentration in the sewage stored in the aeration tank 2. Thereby, the power consumption of the pump 51 can be suppressed. Further, since the supply port 30 opens downward, even if viscous substances or solids such as sludge settle from above, the supply port 30 will not be blocked and clogged. In addition, since the fine bubble liquid is directly supplied from the liquid feeding device 5 to the aeration tank 2, a rotary joint 321 or the like becomes unnecessary, and the bubble supply facility 1 can be configured at low cost.

[0051] Next, a modification of the bubble supply facility 1 of the second embodiment will be described. In the description of this modification, mainly the differences from the second embodiment will be described, and the descriptions overlapping with the second embodiment may be omitted.

[0052] FIG. 9 is a cross-sectional view similar to FIG. 8 showing a bubble supply facility according to a modification of the second embodiment.

[0053] As shown in FIG. 9, the bubble supply facility 1 of this modification is different from the second embodiment shown in FIG. 8 in that the tip portion of the bubble liquid delivery pipe 52 is directed horizontally. The tip portion of the bubble liquid delivery pipe 52 extends horizontally from near the side wall of the aeration tank 2 to near the blade 31. Therefore, the supply port 30 formed at the tip of the bubble liquid delivery pipe 52 opens laterally. The water sucked up by the pump 51 is generated as a fine bubble liquid with fine bubbles added by the bubble liquid generator 53. Then, the generated fine bubble liquid is discharged laterally from the supply port 30 in the vicinity of the blade 31. In FIG. 9, the discharge direction of the fine bubble liquid is indicated by a straight arrow.

[0054] This modified bubble supply facility 1 also has the same effects as the bubble supply facility 1 of the second embodiment. Furthermore, since the supply port 30 is arranged in the vicinity of the blade 31, the stirring performance of the fine bubble liquid is enhanced.

[0055] The present invention is not limited to the above-described embodiments and can be variously modified within the scope described in the claims. For example, in this embodiment, the bubble supply facility 1 has been described by way of an example applied to a sewage treatment plant, but it may also be applied to a fish farm or the like. When used in a sewage treatment plant, the bubble supply facility of the present invention may be applied as a liquid treatment facility that switches between anaerobic biological treatment or biological treatment in an anaerobic state and aerobic biological treatment. When performing anaerobic biological treatment or biological treatment in an anaerobic state, the pump 51 of the liquid delivery device 5 may be stopped constantly. Further, in the description of this embodiment, the concentration sensor 6 was arranged in the aeration tank 2 to control the supply amount of the fine bubble liquid, but the supply amount of the fine bubble liquid may be controlled according to the inflow amount of sewage into the aeration tank 2 or the like without using the concentration sensor 6. Furthermore, in this embodiment, the supply port 30 is provided below the water surface WL of the sewage stored in the aeration tank 2, but the supply port 30 may be provided above the water surface WL and fine bubble water may be discharged from above toward the water surface WL. In addition, a flow rate adjustment valve may be provided in the middle of the bubble liquid delivery pipe 52, upstream or downstream of the bubble liquid generation device, and the opening degree of the flow rate adjustment valve may be controlled by the control device 7. Also, a solar power generation device to be used when the power supply stops due to a disaster or the like may be provided in the bubble supply facility 1. Since the bubble supply facility 1 of the present invention can be driven with less power, the bubble supply facility 1 can be driven even if the power generated by the solar power generation device is small.

[0056] According to the embodiments and modification examples described above, it is possible to provide the bubble supply facility 1 that suppresses the consumption of electric power.

[0057] Note that even constituent elements included only in the description of each of the above-described embodiments and each modification example may be applied to other embodiments and other modification examples.

[0058] The bubble supply facility described above includes a storage tank that stores a liquid containing viscous substances and solid substances, a stirring device that includes a rotating part that rotates in the storage tank and stirs the liquid stored in the storage tank, a supply port that supplies a fine bubble liquid to the storage tank, A liquid feeding device for sending out the fine bubble liquid to the supply port, and a supply amount adjusting means for adjusting the supply amount of the fine bubble liquid supplied from the supply port. The rotating part forms a circulating flow of the liquid downward in the storage tank in the vicinity of the rotating part. The supply port is characterized in that the fine bubble liquid is supplied downward along the circulating flow.

[0059] The rotating part has blades and a shaft. The supply port may be provided at the lower end of the shaft.

[0060] Also, a storage tank for storing a liquid, a stirring device for stirring the liquid stored in the storage tank, a supply port for supplying a fine bubble liquid to the storage tank, a liquid feeding device for sending out the fine bubble liquid to the supply port, and a supply amount adjusting means for adjusting the supply amount of the fine bubble liquid supplied from the supply port.

[0061] Here, the liquid feeding device may include a bubble liquid generating device for generating the fine bubble liquid. Also, the liquid feeding device has a pump, and the supply amount adjusting means may include a control means for controlling the pump. And the supply amount adjusting means may intermittently drive the pump.

[0062] According to this bubble supply facility, since the fine bubble liquid is supplied to the storage tank, the power consumption can be reduced compared to sending air to the bottom of the tank. Also, since most of the fine bubbles contained in the supplied fine bubble liquid mix with the liquid, it is not necessary to eject a large amount of bubbles into the liquid. Furthermore, since the stirring device is provided, there is no need to supply bubbles for stirring, and since the fine bubble liquid is supplied, there is also no need to supply bubbles to prevent clogging of the supply port. And since the supply amount adjusting means adjusts the supply amount of the fine bubble liquid, the power consumption in the liquid feeding mechanism can be suppressed.

[0063] In this bubble supply facility, it is provided with a concentration sensor for detecting the dissolved oxygen concentration contained in the liquid stored in the storage tank. The supply amount adjusting means may be one that adjusts the supply amount of the fine bubble liquid supplied from the supply port according to the dissolved oxygen concentration detected by the concentration sensor.

[0064] By controlling the supply amount of the fine bubble liquid according to the dissolved oxygen concentration, it is possible to prevent excessive supply of the fine bubble liquid while ensuring the required amount of oxygen in the liquid, so that the power consumption in the bubble supply facility can be efficiently reduced.

[0065] Furthermore, in this bubble supply facility, the stirring device is provided with a rotating part that rotates in the storage tank. The supply port may be formed in the rotating part.

[0066] Since the supply port is formed in the rotating part, the risk of sludge or the like remaining in the supply port and causing clogging can be further reduced.

[0067] Also, in this bubble supply facility, the supply port may discharge the fine bubble liquid in a direction opposite to the rotation direction of the rotating part.

[0068] By doing so, since the fine bubble liquid is discharged into the liquid by the rotation of the rotating part, the power in the liquid feeding mechanism can be further reduced.

[0069] Also, in this bubble supply facility, the supply port may discharge the fine bubble liquid toward the radial direction of the rotation radius of the rotating part.

[0070] By doing so, since the fine bubble liquid is discharged into the liquid by the centrifugal force due to the rotation of the rotating part, the power in the liquid feeding mechanism can be further reduced.

[0071] Also, in this bubble supply facility, the supply port may be in an opening mode facing downward or horizontally.

[0072] According to this mode, viscous substances and solids such as sludge settle from above the supply port and it is also difficult to block the supply port, so clogging of the supply port can be further suppressed.

[0073] Also, the bubble supply facility described above includes a storage tank for storing a liquid containing viscous substances and solids and, a stirring device for stirring the liquid stored in the storage tank, a supply port for supplying a fine bubble liquid to the storage tank, and a liquid feeding device for sending out the fine bubble liquid to the supply port, the stirring device forms a circulating flow of the liquid having a downward flow in the storage tank and, the supply port is characterized by supplying the fine bubble liquid downward along the circulating flow.

[0074] In this bubble supply facility, a supply amount adjusting means for adjusting the supply amount of the fine bubble liquid supplied from the supply port may be provided.

[0075] ​ The bubble supply facility described above stores a liquid containing viscous substances and solids in a storage tank, a stirring device that stirs the liquid stored in the storage tank, a supply port that supplies fine bubble liquid to the storage tank, and a liquid feeding device that sends out the fine bubble liquid to the supply port, and is characterized in that the stirring device has blades arranged in a horizontally open area and a shaft fixed to the lower end portion thereof to rotate the blades, and forms a circulating flow of the liquid having a downward flow in the storage tank, and the supply port is formed at the lower end of the shaft and supplies the fine bubble liquid downward along the circulating flow in the horizontally open area.

[0076] In this bubble supply facility, it may further include a concentration sensor that detects the dissolved oxygen concentration contained in the liquid stored in the storage tank, and supply amount adjusting means that adjusts the supply amount of the fine bubble liquid supplied from the supply port according to the dissolved oxygen concentration detected by the concentration sensor.

Explanation of Reference Numerals

[0077] 1 Bubble supply facility 2 Anaerobic tank 3 Stirring device 6 Concentration sensor 30 Supply port 51 Pump 53 Flow rate regulating valve

Claims

1. A storage tank for storing a liquid containing viscous and solid matter; A stirring device that stirs the liquid stored in the storage tank; A supply port for supplying fine bubble liquid to the storage tank; A liquid delivery device having a pump for delivering the fine bubble liquid to the supply port; and a supply amount adjustment means for adjusting the amount of the fine bubble liquid supplied from the supply port by intermittently driving the pump.

2. 2. The air bubble supply facility according to claim 1, wherein the pump has a constant suction volume.

3. The stirring device has a shaft that rotates around an axis, 3. The air bubble supply facility according to claim 1, wherein the supply port is provided in a plurality of locations spaced apart from one another in the extension direction of the shaft.

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