JPH0312399Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a sewage aeration device that can adjust the circulation flow rate of sewage and the flow rate of gas mixed into the sewage.

(Prior art) A sewage aeration system used in the conventional activated sludge treatment method, which is commonly used for sewage treatment, is equipped with an aeration pipe at the bottom of the aeration tank. It is configured to erupt. This configuration is widely used because it has a simple structure and can be constructed at low equipment cost. However, the air diffuser pipes are easily clogged, and the fine air bubbles released from the air diffuser pipes become large lumps during the floating process and drift, resulting in insufficient mixing of wastewater and air, making it difficult to obtain a sufficient aeration effect. I had a problem where I couldn't do it.

In addition, in order to avoid performance deterioration due to the bulking phenomenon that is unique to activated sludge treatment methods, it is known that the submerged filter treatment method, which is a type of biofilm method, has been improved, and various sewage aeration devices have been proposed for this purpose. . In this immersed filter bed type wastewater aeration device, a filter bed body made of a honeycomb core or a net ring is immersed in wastewater.
A vertical pipe provided in the center of the filter bed is used as a circulation flow path, and the wastewater mixed with air is circulated through the filter bed several times and treated. As a technique for mixing air with wastewater and circulating it, for example, as shown in Utility Model Publication No. 18320/1983,
There is an air lift pump that sends compressed air into the lower part of a vertical pipe to create an upward flow within the vertical pipe, and also attempts to bring the air and wastewater into contact during the process of rising within the vertical pipe. In addition, as shown in Utility Model Publication No. 56-1439, an axial flow impeller partially immersed in the wastewater surface above the vertical pipe is rotated to create a downward flow of a gas-liquid mixture into the vertical pipe while drawing in air. There is something that makes me Furthermore, as shown in Utility Model Publication No. 58-26077, an axial flow impeller is arranged in a vertical pipe, and an air pipe communicating with outside air is opened near the suction side of this axial flow impeller. There are devices that circulate wastewater by suctioning air with the negative pressure generated by the rotation of the pump, and also mix air into the wastewater.

(Problems to be solved by the invention) By the way, in the immersion filter bed type wastewater aeration equipment, the faster the circulating flow rate, the more times the wastewater comes into contact with the filter bed body, and the treatment performance improves. performance in the spring is improved. This is illustrated by the experimental data in FIGS. 6 and 7. Figure 6 shows the winter season (January)
Fig. 7 is a characteristic diagram when the relationship between the circulation flow rate in the filter bed and the ammonia nitrogen removal rate was tested by changing the water amount load, and Fig. 7 is a characteristic diagram in the case of the spring season (May).

As is clear from Figures 6 and 7, in the winter, the higher the circulation flow rate, the higher the ammonia nitrogen removal rate, but in the spring, when the circulation flow rate exceeds a certain value, the ammonia nitrogen removal rate increases. Nitrogen removal rate does not increase with circulation flow rate. Furthermore, the processing performance in spring is superior to that in winter.

Here, in order to most economically maintain constant good treatment performance throughout the year, it is desirable to increase the circulation flow rate in winter and lower the circulation flow rate in spring than in winter.

However, conventional submerged filter bed type wastewater aeration equipment has the following drawbacks. first,
When circulating using an air lift pump that sends compressed air to the bottom of a vertical pipe, it is not possible to increase the circulation flow rate in the vertical pipe above the floating speed of the bubbles.
In addition, power costs increase due to pumping a large amount of air,
Moreover, the air bubbles become large and the sewage and air cannot be brought into contact and mixed sufficiently, making it impossible to obtain a sufficient aeration effect. In addition, with impellers, it is possible to adjust the circulating flow velocity in the vertical pipe by adjusting the rotation speed of the impeller, but it requires a speed conversion means etc. to adjust the rotation speed, and this is not enough. Equipment costs will be higher.

The purpose of the present invention was to solve the above-mentioned problems of conventional sewage aeration equipment, and to provide a sewage aeration equipment that can arbitrarily and independently adjust the circulation flow rate of sewage and the flow rate of gas sucked into the sewage. There is a particular thing.

(Means for solving the problem) In order to achieve the above object, the sewage aeration device of the present invention has an axial flow impeller and a ventilate pipe arranged in series in a water flow pipe, and a throat part of the ventilary pipe. a plurality of air holes communicating with the gas supply means are bored, and conical cones are disposed facing each other at at least one end of the water flow pipe to form a circumferential opening;
A slide gate is provided to open and close this opening.

(Function) A circumferential opening is formed by arranging conical cones facing each other at at least one end of a water pipe in which an axial impeller is installed, and adjusting a slide gate that opens and closes this opening. The discharge flow rate is adjusted, and the circulating flow rate of wastewater can be adjusted arbitrarily without providing a speed converting means or the like to the axial flow impeller. In addition, a plurality of pores are drilled in the throat of the ventilate tube installed in the water pipe, and these pores are communicated with the gas supply means, so that the negative pressure generated by the high-speed flow of wastewater passing through the throat can be applied to the pores. Gas is sucked into the wastewater. Then, by appropriately adjusting the gas supply by the gas supply means using a throttle valve or the like, the flow rate of the gas sucked into the wastewater can be arbitrarily adjusted.

(Example) Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 3. Fig. 1 is a longitudinal sectional view of the wastewater aeration device of the present invention, Fig. 2 is an enlarged longitudinal sectional view of the slide gate portion of Fig. 1, and Fig. 3 is a discharge flow rate by adjusting the slide gate. FIG.

1 and 2, a filter bed body 2 such as a honeycomb core or a net ring is immersed below the water surface in a sewage treatment tank 1 and is placed at a predetermined distance from the bottom of the sewage treatment tank 1. A vertical pipe 3 serving as a water flow pipe is disposed in the center of the filter bed body 2 with its ends slightly protruding above and below the filter bed body 2. Further, conical cones 4 and 5 are disposed to face the openings at both upper and lower ends of the vertical tube 3, respectively. This upper conical cone 4 is provided with an axial flow impeller 7 driven and rotated by a motor 6. An opening 8 on the circumference is formed by the upper edge of the vertical pipe 3 and the upper cone 4, and the wastewater flows radially from this opening 8 in a plane substantially orthogonal to the axis of the vertical pipe 3. It is discharged.
Further, a slide gate 9 is fitted to the upper end of the vertical tube 3 so as to be slidable in the vertical direction, and the opening 8 is adjusted to open or close as appropriate depending on the vertical position of the slide gate 9.

Further, a ventilate tube 10 is provided in the middle of the vertical tube 3, and the circumferential wall of the ventilic tube 10 and the circumferential wall of the vertical tube 3 form an annular air chamber 11 serving as a gas supply means. One end of an air pipe 12 is opened in this annular air chamber 11, and the other end is opened to the atmosphere via a throttle valve 13. Furthermore, a large number of small-diameter pores 14, 14, . . . are bored in the peripheral wall of the throat portion of the ventilate tube 10, which has the narrowest inner diameter.

The opening/closing mechanism of the slide gate 9 is constructed by installing an electric device 16 and a manual device 17 on a pedestal 15 installed above the vertical pipe 3 and above the sewage treatment tank 1, and a drive rod 18 connected to these devices 16 and 17. is connected to one end of swinging arms 19, 19 which are vertically swingable, and the other ends of the swinging arms 19, 19 are connected to the slide gate 9 via operating rods 20, 20. Then, the sliding range of the slide gate 9 is appropriately limited by a limit switch or a stopper.

In addition, in FIG. 1, 21 is a sludge scraping machine for scraping up the sludge that has separated and settled from the filter bed body 2 and discharging it from a sludge discharge port (not shown).

In this configuration, by driving and rotating the axial flow impeller 7, an upward flow is generated within the vertical pipe 3. Then, the sewage sucked into the vertical pipe 3 from the bottom is discharged radially from the opening 3 at the top, descends through the filter bed body 2, and is sucked in again from the bottom of the vertical pipe 3, and the sewage flows through the filter bed body. 2 repeatedly.

Here, if the slide gate 9 is lowered to the lowest position and the opening 8 is opened wide, the fluid resistance is small and the third
As shown by the solid line in the figure, a large discharge flow rate can be obtained and water flow can be generated over a wide range. Also, if the slide gate 9 is raised to make the opening 8 smaller,
The fluid resistance increases, a small discharge flow rate is obtained as shown by the broken line in FIG. 3, and water flow can only be generated in a narrow range. Therefore, the circulation flow rate of wastewater in the wastewater treatment tank 1 can be arbitrarily adjusted by adjusting the slide gate.

Furthermore, if the throttle valve 13 is opened to allow the annular air chamber 11 to communicate with the atmosphere via the air pipe 12 with minimal resistance, then in response to the negative pressure created in the ventilate pipe 10 with the high velocity flow of waste water through the vertical pipe 3, , stomata 1
4, 14..., the faster the wastewater flows, the more air is sucked into the wastewater as bubbles, and these small bubbles are further atomized by the impeller 7 and discharged from the opening 8 as a gas-liquid mixed flow. . In addition, if the opening degree of the throttle valve 13 is made small to allow the annular air chamber 11 to communicate with the atmosphere with a large resistance, the pores 1
The amount of air sucked in from 4, 14, etc. becomes smaller. If the throttle valve 13 is closed, air will not be mixed into the wastewater.

Therefore, by adjusting the slide gate 9 and adjusting the throttle valve 13, the circulating flow rate of the waste water and the flow rate of air mixed into the waste water can be independently and appropriately adjusted.

Moreover, if the axial flow impeller 7 is rotated in the opposite direction, a downward flow is generated in the vertical pipe 3, and the lower conical cone 5
As a result, wastewater is discharged radially to the lower part of the filter bed body 2. Then, the clogging of the filter bed body 2 can be eliminated by the sewage passing upward through the filter bed body 2 in a direction opposite to the normal direction.

Another embodiment of the present invention will be described with reference to FIGS. 4 and 5. FIG. 4 is a longitudinal cross-sectional view of another embodiment of the sewage aeration device of the present invention, and FIG.
5 is an external view illustrating the slide gate of FIG. 4. FIG. In FIGS. 4 and 5, the same or equivalent members as in FIGS. 1 and 2 are given the same reference numerals and redundant explanations will be omitted.

In FIGS. 4 and 5, a motor 6 and an axial impeller 7 are disposed at the top of the vertical tube 3, and the upper edge of the vertical tube 3 is opened in a bell shape. A lower conical cone 5 is disposed opposite the lower end opening of the vertical tube 3. A circumferential opening 8 is formed by this lower conical cone 5 and the lower edge of the vertical tube 3. Further, a slide gate 9 is fitted to the lower end of the vertical tube 3 so as to be slidable in the vertical direction, and the opening 8 is adjusted to open or close as appropriate depending on the vertical position of the slide gate 9.

The opening mechanism of the slide gate 9 includes a swing arm in which a drive rod 18 connected to an electric device 16 and a manual device 17 to move up and down is swingably disposed about a shaft 22 provided at the bottom of the vertical pipe 3. The swing arm 19 is connected to one end of the swing arm 19, and the other end of the swing arm 19 is connected to the slide gate 9 via an operating rod 20.

In this configuration, the axial impeller 7 is driven and rotated to generate a downward flow in the vertical pipe 3, and the high-speed flow of wastewater passing through the throat portion of the ventilate pipe 10 causes air to be sucked into the wastewater as bubbles, thereby creating a gas-liquid state. The mixed flow is discharged radially from the lower part of the vertical pipe 3 to the lower part of the filter bed body 2. Then, due to the buoyant force of the mixed air bubbles, the wastewater rises and passes through the filter bed body 2 at high speed.

If the axial flow impeller 7 is rotated in the opposite direction to the above description, the sewage will descend within the filter bed body 2, and the exfoliated sludge that clogs the filter bed body 2 can be more reliably settled.

In the above embodiment, the vertical pipe 3 serving as a water pipe was installed vertically in the center of the filter bed 2, but in order to aerate an oxygen-deficient area such as a lake or pond, A water pipe in which the axial impeller 7, the ventilate tube 10, etc. are disposed may be disposed diagonally or horizontally in the water in an oxygen-deficient portion. Further, in the above embodiment, the axial flow impeller 7 is arranged at the upper part of the vertical pipe 3, but the impeller 7 is not limited to this, and may be arranged at either the lower part or the middle part of the vertical pipe 3. The ventilator tube 10 is not limited to the one arranged in the middle part of the vertical tube 3, and the axial flow impeller 7
It may be arranged at either the upper or lower part of the vertical tube 3 so that it is arranged in series with the vertical pipe 3. Further, although the annular air chamber 11 was formed by the ventilate tube 10 and the peripheral wall of the vertical tube 3, the gas supply means may have any configuration as long as a chamber communicating with the pores 14, 14, . . . is formed. Of course, compressed air or a gas other than air may also be fed into the annular air chamber 11.

(Effects of the invention) As explained above, according to the wastewater aeration system of the invention, the circulation flow rate of wastewater and the flow rate of gas sucked into wastewater can be independently and appropriately adjusted, so that a constant treatment performance can be maintained throughout the year. you can get
Moreover, there is no waste in power costs and it is economical. Also,
Since no speed conversion means or the like is required to adjust the circulating flow speed, equipment costs are low. Furthermore, it has an excellent effect that it can be used not only for aerobic treatment of sewage, but also for anaerobic treatment of sewage by cutting off the supply of gas to the gas supply means.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view of the wastewater aeration device of the present invention, Fig. 2 is an enlarged longitudinal sectional view of the slide gate portion of Fig. 1, and Fig. 3 is a discharge flow rate by adjusting the slide gate. FIG. 4 is a longitudinal sectional view of another embodiment of the wastewater aeration device of the present invention, and FIG. 5 is an external view illustrating the slide gate of FIG. 4. Figure 6 is a characteristic diagram of the relationship between the circulation flow rate in the filter bed and the ammonia nitrogen removal rate in the winter (January) when the water volume load was changed, and Figure 7 is the characteristic diagram for the relationship between the circulation flow rate in the filter bed and the ammonia nitrogen removal rate in the winter (January). FIG. 3: vertical tube, 4, 5: conical cone, 6: motor, 7: axial flow impeller, 8: opening, 9: slide gate, 10: ventilate tube, 11: annular air chamber, 12: air tube, 13: Throttle valve, 14: Stomata.

Claims (1)

[Claims for Utility Model Registration] (1) An axial impeller and a ventilate tube are arranged in series in a water flow pipe, and a plurality of air holes communicating with a gas supply means are bored in the throat portion of the ventilate pipe, A sewage aeration system, characterized in that a conical cone is disposed facing each other at at least one end of the water pipe to form a circumferential opening, and a slide gate for opening and closing this opening is disposed. (2) The sewage aeration device according to claim 1, wherein the gas supply means includes a throttle valve that adjusts the flow rate of the gas to be supplied. (3) The sewage aeration device according to claim 1 or 2, wherein the axial flow impeller can be switched between forward and reverse rotations.