JP3251233B2 - Coagulation sedimentation equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for coagulating and sedimenting suspended substances and the like in a liquid to be treated in a sedimentation tank to clarify the liquid to be treated.

[0002]

2. Description of the Related Art Conventionally, techniques in such a field include:
One disclosed in Japanese Patent Publication No. 38523/1993 is known. The conventional coagulation and sedimentation apparatus described in this publication has a mixing chamber (feed supply pipe) rotatably provided upright in a sedimentation tank, and a blow-off pipe provided at a lower end portion of the mixing chamber. . In recent years, a coagulating sedimentation apparatus has been known in which a mixing chamber is fixed in an upright state in a sedimentation tank, and a distributor having a blowing pipe is rotatably provided at a lower end of the mixing chamber.

When a clear supernatant is obtained by using these coagulation and sedimentation apparatuses, a predetermined additive is introduced into a mixing chamber together with a liquid to be treated such as raw wastewater, and both are provided in the mixing chamber. Mix and stir with a turbine. As a result, suspended substances and the like in the liquid to be treated are aggregated to form flocs, and the liquid to be treated including the aggregated flocs is distributed and supplied into the sedimentation tank from the rotating blowing pipe. Then, the flocculated flocs in the liquid to be treated settle and separate in the settling tank, and the clear supernatant liquid rises and flows out from the upper part of the settling tank.

[0004]

The above-mentioned coagulation sedimentation apparatus is used for various purposes such as wastewater treatment and papermaking white water recovery. In recent years, however, from the viewpoint of improving the quality of various industrial products and protecting the environment, For example, if the suspended particle concentration is 10
There is a growing need for a coagulating sedimentation apparatus capable of obtaining a very clarified supernatant liquid of not more than ppm.

Accordingly, an object of the present invention is to provide a coagulation sedimentation apparatus capable of obtaining a very clarified supernatant.

[0006]

According to a first aspect of the present invention, there is provided a coagulation / sedimentation apparatus for mixing and stirring a liquid to be treated and an additive in a mixing chamber which is set upright in a sedimentation tank, and a central shaft of the mixing chamber. In a coagulation and sedimentation device that clarifies the liquid to be treated by discharging the liquid to be treated into the sedimentation tank from a discharge pipe that can rotate around, the upper surface of the discharge pipe, and the inner peripheral surface of the sedimentation tank and the outer peripheral surface of the mixing chamber And at least one swirl flow prevention member extending in a direction perpendicular to the central axis.

A coagulating sedimentation apparatus of the type in which a liquid to be treated and an additive are mixed and stirred in a mixing chamber and a liquid to be treated including flocculated flocs is distributed and supplied from a rotating blow-off pipe into the sedimentation tank. Since the ascending flow can be equalized, it has a high sedimentation separation efficiency. On the other hand, there is a growing need for a coagulating sedimentation device that can obtain an extremely clear supernatant,
The present inventors have intensively studied to further improve the performance of such a coagulating sedimentation apparatus of the rotary distribution type.

As a result, in the coagulating sedimentation apparatus of the rotary distribution type, a swirling flow is generated above the blowing pipe in the sedimentation tank due to the rotation of the blowing pipe, and it is possible to obtain extremely clarified treated water. In this case, it has been found that this swirling flow greatly affects the clarity of the supernatant. That is, when the flow velocity (rising speed) of the swirling flow generated in the sedimentation tank due to the rotation of the blowing pipe is faster than the sedimentation speed of the flocculated floc settling in the sedimentation tank, the fine flocculent floc is formed in the sedimentation tank. And rises with the swirling flow and floats in the supernatant without settling. As a result, it was found that it was difficult to reduce the concentration of suspended particles in the supernatant to a desired level.

In view of the above research results, in the present invention, at least one swirling flow preventing member is provided above the blowout pipe in the settling tank and between the inner peripheral surface of the settling tank and the outer peripheral surface of the mixing chamber. It is stretched. Thus, during the operation of the coagulating sedimentation apparatus, the swirling flow generated due to the rotation of the blow-out pipe collides with the swirling flow prevention member when rising while rotating in the sedimentation tank from near the blow-out pipe. . Therefore, the curling of fine flocs above the blow-out pipe and below the clarified liquid level in the settling tank is suppressed, so that the suspended particle concentration of the supernatant liquid can be reduced to a desired level.
Further, since the swirling flow prevention member is stretched in a direction orthogonal to the center axis of the mixing chamber, the swirling flow prevention member and the swirling flow are substantially orthogonal to each other, and the occurrence of further drift is suppressed. Is done.

In this case, it is preferable that the swirl flow preventing member is formed of a sheet material. By employing such a configuration, the swirl flow prevention member can be simply configured, and its manufacturing cost can be reduced. Further, the swirl flow preventing member may be formed of a steel plate, and is effective when it is desired to secure the rigidity of the swirl flow preventing member.

Further, the swirling flow prevention member is formed as a rectangular sheet having a cylindrical portion at an upper edge and a lower edge, a wire is inserted into each cylindrical portion, and the wire is stretched between the settling tank and the mixing chamber. It is preferable to install in the sedimentation tank by installing. If such a configuration is adopted, the wire used for positioning (centering) of the mixing chamber is
It can also be used for attaching a swirling flow prevention member.
In addition, workability when attaching the swirl flow prevention member to the settling tank is improved, and the overall cost associated with providing the swirl flow prevention member can be reduced. Further, depending on the operation mode of the coagulation and sedimentation apparatus, the swirl flow prevention member may not be necessary. However, even in such a case, the swirl flow prevention member can be easily removed. Performance can be improved.

Here, it is preferable that the distance between the lower edge of the swirling flow preventing member and the blow-out pipe is 200 mm to 1000 mm. By adopting such a configuration, it is possible to suppress the swirling flow without impairing the smooth rotation of the blow-out pipe.

It is preferable that four swirl flow preventing members are provided, and each of the swirl flow preventive members is attached at 90 ° intervals around the mixing chamber. By adopting such a configuration, it is possible to effectively suppress the swirling flow particularly in a large-sized coagulation-sedimentation apparatus.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the coagulation and sedimentation apparatus according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a partial sectional view showing a coagulating sedimentation apparatus according to the present invention. The coagulating sedimentation apparatus 1 shown in the figure can perform so-called sludge circulation operation and sludge blanket operation according to the characteristics of the liquid to be treated, and can perform wastewater treatment, papermaking white water recovery, DIP wastewater recovery, and caustic greening. It can be applied to various uses such as liquid clarification, water treatment, and inorganic precipitate washing treatment. The coagulating sedimentation apparatus 1 has a sedimentation tank 2 for clarifying a liquid to be treated such as raw wastewater.
Is formed in a bottomed cylindrical shape having a tank depth of about 4000 to 5000 mm. The diameter of the sedimentation tank 2 is set to 1500 to 3000 in accordance with the installation space and the characteristics and amount of the liquid to be treated.
It is set arbitrarily within a range of about 0 mm. The sedimentation tank 2
It is fixed on a base portion 3 provided in a space where the coagulation and sedimentation device 1 is installed. The base 3 is formed of concrete or the like.

The coagulating sedimentation apparatus 1 has a gantry 4 installed on the upper edge of the sedimentation tank 2. The gantry 4 is mainly used as a work space for workers during various maintenance work. A mixing chamber 5 is suspended from the center of the gantry 4. The mixing chamber 5 is formed in a cylindrical shape, and has a height of, for example, about two thirds of the tank depth of the settling tank. Mixing chamber 5
Is fixed to the gantry 4 with its central axis aligned with the central axis of the sedimentation tank 2. As a result, the mixing chamber 5 is fixed upright in the sedimentation tank 2 and
A predetermined space (space) is formed between the lower edge of the mixing chamber 5 and the bottom of the sedimentation tank 2.

In the upper part of the mixing chamber 5, an inlet pipe 6 communicating with a processing liquid inlet pipe 6 connected to an external pump or the like is provided.
a is connected. That is, in the coagulation sedimentation apparatus 1, a liquid to be treated such as raw wastewater is first introduced into the mixing chamber 5 via the introduction pipe 6a. The introduction pipe 6a is provided for clarifying the liquid level during the operation of the coagulation and sedimentation apparatus 1,
And, it is provided below the liquid level in the mixing chamber 5. This prevents generation of bubbles and the like due to the introduction of the liquid to be treated.

The mixing chamber 5 is provided with a plurality of injection nozzles 7 for injecting various additives for coagulating suspended substances and the like in the liquid to be processed. As the additive to be introduced into the mixing chamber 5, various polymer coagulants or the like are employed depending on the characteristics of the liquid to be treated. Each injection nozzle 7 is disposed along the height direction of the mixing chamber 5, and is provided, for example, one at a time in the upper, middle, and lower stages of the mixing chamber 5. Further, an additive introduction pump (not shown) is connected to the injection nozzle 7, and the injection amount of the additive can be controlled for each injection nozzle 7.

Further, as shown in FIG. 1, the mixing chamber 5 has a built-in stirring turbine 8 for mixing and stirring the liquid to be treated and the additive. The stirring turbine 8
It is formed as a hollow cylinder with a plurality of stirring blades,
The center axis is aligned with the center axis of the mixing chamber 5 and is rotatably suspended from the gantry 4. During the operation of the coagulation and sedimentation apparatus 1, the stirring turbine 8 is rotated by the turbine drive unit 8a mounted on the gantry 4. Further, a center shaft 9 is inserted into the stirring turbine 8. The center shaft 9 is also rotatably suspended from the gantry 4 with its central axis coinciding with the central axis of the mixing chamber 5, and is rotationally driven by a drive unit 9a mounted on the gantry 4. .

A distributor 10 is fixed to the center shaft 9. Distributor 1
0 is connected to the lower end of the mixing chamber 5,
It functions as a bottom for the mixing chamber 5 and is rotatable around the center axis of the mixing chamber 5 by rotation of the center shaft 9. The distributor 10 has a plurality of (for example, four) outlet pipes 11, and a plurality of outlet holes 11 a is formed below each of the outlet pipes 11. During the operation of the coagulation and sedimentation apparatus 1, the distributor 10 is rotated by the driving unit 9a, and the liquid to be treated including the coagulation flocs in the mixing chamber 5 is discharged into the sedimentation tank 2 from each of the outlets 11a. Thereby, a uniform ascending flow can be obtained without generating a drift or a short circuit in the sedimentation tank 2.

A baffle plate 12 is mounted below each of the outlet pipes 11a. As a result, the liquid to be treated discharged from the outlet 11 a is supplied to the lower part of the sedimentation tank 2 through the baffle plate 12, so that the liquid to be treated discharged from the outlet pipe 11 may agitate the flocculated flocs. Thus, the sedimentation and separation efficiency of the coagulation and sedimentation apparatus 1 is further improved. If the diameter of the blowing pipe 11 is increased, a swirling flow may be excessively generated in the sedimentation tank. Therefore, the blowing pipe 11 may be formed to have a small diameter. When the tank diameter of the settling tank 2 is large,
It is advisable to increase the number of outlet pipes 11 such as 6, 8, 10, or 12 pipes.

Here, in a rotary distribution type coagulation and sedimentation apparatus such as the coagulation and sedimentation apparatus 1, since the distributor 10 must be rotated smoothly, a certain gap is provided between the mixing chamber 5 and the distributor 10. Need to be formed. However, the inventors of the present invention have conducted intensive studies, and found that the liquid to be treated, when being sent from the mixing chamber 5 to the blow-out tube 11, does not pass between the mixing chamber 5 and the distributor 10 without passing through the blow-out tube 11. It has been found that discharge (short circuit) may occur directly into the precipitation tank 2 from the gap. And
The amount of the liquid to be treated that is short-circuited in this way is not small at all, and this short-circuit phenomenon has a great effect on the clarity of the supernatant when attempting to obtain extremely purified treated water. That was found.

Therefore, in the coagulating sedimentation apparatus 1, as shown in FIG. 2, a so-called non-contact type sealing portion 1 is provided in a gap between the mixing chamber 5 and the distributor 10.
4 are provided. The seal portion 14 includes an engaging portion 15 provided at an upper portion of the distributor 10 and a drainage flange 16 provided at a lower portion of the inner peripheral surface of the mixing chamber 5.
And formed as a labyrinth. Engaging part 1
5 is formed in a low cylindrical shape having an outer diameter smaller than the inner diameter of the mixing chamber 5. The distributor 10 is fixed to the center shaft 9 with the engaging portion 15 inserted into the lower end of the mixing chamber 5, and functions as a bottom for the mixing chamber 5.

The drainage flange 16 is a ring-shaped plate formed of a steel plate or the like, has an outer diameter that is substantially the same as the inner diameter of the mixing chamber 5, and has an inner diameter smaller than the inner diameter of the engaging portion 15. The drainage flange 16 is horizontally fixed to the lower portion of the inner peripheral surface of the mixing chamber 5 by means such as welding. The lower surface of the drainage flange 16 is opposed to the upper end surface of the engaging portion 15, and a predetermined interval is formed between the two. In addition, the draining flange 16
, A draining lip 17 is fixed as shown in FIG. The draining lip 17 is formed by forming a narrow long plate into a ring shape, and is fixed to the inner peripheral portion of the draining flange 16 so that the outer peripheral surface is along the inner peripheral surface of the engaging portion 15. A predetermined interval is also formed between the outer peripheral surface of the drain lip 17 and the inner peripheral surface of the engagement portion 15.

The lower edge of the mixing chamber 5 is
As shown in FIG. 2, it is formed as a flange portion 5a. Two packings 19 are fixed to the flange portion 5 a via bolts and nuts and a holding plate 20.
The packing 19 is formed by forming a synthetic resin sheet or the like into a ring shape. The inner peripheral portion of each packing 19 is bent downward, and the upper packing 19 contacts the outer peripheral surface of the engaging portion 15. When the distributor 10 is rotating, the packing 19 fixed to the mixing chamber 5 slides with respect to the engagement portion 15. Thereby, the sealing effect is further improved.

Each packing 19 is provided in the mixing chamber 5.
After connecting the distributor 10 to the lower end of the flange 5a, the distributor 10 is attached to the flange portion 5a. In this case, first, FIG.
As shown in (1), a slit 19a is formed at one location in the circumferential direction of the packing 19. And the slit 19
a each packing 19 using the distributor 10
Along the engaging portion 15 of the second member. When two packings 19 are stacked, the slits 19a of each packing 19 are prevented from overlapping each other. Then, each packing 19 is fixed to the flange portion 5a via the bolt / nut and the holding plate 20. Thereby, the mountability of the packing 19 can be improved while maintaining the sealing effect of the packing 19 well. In the case where the diameter of the mixing chamber 5 is large, a packing 19 formed in a semicircular ring shape may be used and fixed to the flange portion 5a so as to sandwich the engaging portion 15 from both sides. Also in this case, each packing 19
Make sure that the butted parts do not overlap each other.

As described above, by forming the seal portion 14 in the gap between the mixing chamber 5 and the distributor 10, the liquid to be treated flows directly into the precipitation tank 2 from the gap between the mixing chamber 5 and the distributor 10. Discharge is prevented, and the liquid to be treated is reliably discharged from the outlet pipe 11.
Is distributed and supplied into the sedimentation tank 2 from the blowout hole 11a. Therefore, the sedimentation and separation efficiency in the sedimentation tank 2 is improved, and a supernatant liquid with extremely high clarity can be obtained. The packing 19 is connected to the engaging portion 1 of the distributor 10.
5 may be fixed to the outer peripheral surface and slid with respect to the inner peripheral surface of the mixing chamber 5.

On the other hand, the center shaft 9 to which the distributor 10 is fixed as shown in FIG.
Furthermore, it extends below the distributor 10 and reaches the bottom of the settling tank 2. A rake 21 and a cone scraper 22 that rotate together with the distributor 10 are attached to the tip of the center shaft 9. The rake 21 is for agitating sludge formed by settling of flocculated flocs in the liquid to be treated discharged from the blowing pipe 11. Thereby, a concentrated sludge layer is formed in a region below the distributor 10 in the settling tank 2.

Further, the sedimentation tank 2 communicates with a sludge extraction pipe 23 provided in the base part 3 at the center of the bottom surface thereof.
The cone scraper 22 includes the sedimentation tank 2 and the sludge extraction pipe 2.
3 is provided at the connection portion. The sludge extraction pipe 23 is connected to a sludge extraction pump 24 and a sludge return pump 25.
When performing the sludge blanket operation, the sludge extraction pump 24 is operated based on the indication value of an interface detector (not shown) provided in the sedimentation tank 2 to move the concentrated sludge in the sedimentation tank 2 out of the system. By discharging, the interface height of the sludge blanket layer is kept within a certain range. At this time, since the cone scraper 22 is rotating, the concentrated sludge in the settling tank 2 is uniformly discharged. When performing the sludge circulation operation, the sludge return pump 2
5 is operated to return and circulate the sludge. On the other hand, the supernatant is
It flows out of the system from an outlet 26 provided in the upper part of the settling tank 2.

Meanwhile, the coagulating sedimentation apparatus 1 adopting the rotary distribution system has a high sedimentation separation efficiency because the ascending flow in the sedimentation tank 2 can be equalized. On the other hand, there is a growing need for a coagulating sedimentation apparatus capable of obtaining an extremely clarified supernatant. Therefore,
The present inventors have intensively studied to further improve the performance of such a rotary distribution type coagulation and sedimentation apparatus. As a result, in the coagulating sedimentation apparatus of the rotary distribution type, when the blowing pipe is rotated, a swirling flow is generated above the blowing pipe in the sedimentation tank, and it is intended to obtain extremely clarified treated water. ,
It has been found that this swirling flow has a great effect on the clarity of the supernatant.

That is, when the flow velocity (rising speed) of the swirling flow generated in the sedimentation tank with the rotation of the blowing pipe is faster than the sedimentation speed of the flocculated floc settling in the sedimentation tank, the fine flocculent floc Instead of settling in the settling tank, it rises with the swirling flow and floats in the supernatant. As a result, it was found that it was difficult to reduce the concentration of suspended particles in the supernatant to a desired level. Based on the results of this research, as shown in FIG. 1, a swirling flow prevention member 27 is provided between the inner peripheral surface of the sedimentation tank 2 and the outer peripheral surface of the mixing chamber 5 for the coagulation sedimentation apparatus 1. It was decided to.

The swirling flow prevention member 27 is formed in a rectangular sheet shape from a sheet material such as a nylon sheet or cloth coated with vinyl. As shown in FIG. 4, the swirling flow prevention member 27 has a tubular portion 28 formed by folding back and suturing the upper edge and the lower edge thereof. Thus, the swirl flow preventing member 27 can be simply configured, and its manufacturing cost can be reduced.
In order to mount the swirl flow preventing member 27 in the settling tank 2, a wire 30 having a turnbuckle 29 is used as shown in FIG.

In this case, first, the wires 30 are inserted through the respective tubular portions 28 of the swirl flow preventing member 27. Then, the wire 30 to be positioned on the upper side is mixed below the clarified liquid level position (for example, below the introduction pipe 6a) and between the inner peripheral surface of the sedimentation tank 2 and the outer peripheral surface of the mixing chamber 5. The mixing chamber 5 is extended in a direction perpendicular to the central axis of the chamber 5, that is, in a radial direction of the mixing chamber 5. Further, the other wire 30 is stretched just below the upper wire 30 and above the blowout pipe 11 in a direction perpendicular to the center axis of the mixing chamber 5. Thus, the swirling flow prevention member 27 is parallel to the center axis of the mixing chamber 5 and blocks the space between the inner peripheral surface of the sedimentation tank 2 and the outer peripheral surface of the mixing chamber 5 in the radial direction of the sedimentation tank 2. . In addition,
It is preferable that the wire 30 extending above the blow-out pipe 11 is used for positioning (centering) the mixing chamber 5 as the wire 30 for mounting the swirling flow prevention member 27.

Accordingly, the workability when the swirl flow preventing member 27 is mounted in the sedimentation tank 2 is improved, and the overall cost associated with the provision of the swirl flow preventive member 27 can be reduced. Furthermore, the swirling flow prevention member 27 may not be necessary depending on the operation mode of the coagulation and sedimentation apparatus 1, but even in such a case, the swirling flow prevention member 27 can be easily removed. The versatility of the device 1 can be improved.

Here, it is preferable that the distance d between the lower edge of the swirling flow prevention member 27 and the blowing pipe 11 is set between 200 mm and 1000 mm. This makes it possible to suppress the swirling flow without impairing the smooth rotation of the blowing pipe 11. As shown in FIG. 4, a vertically extending reinforcing plate 31 is fixed to the inner peripheral surface of the sedimentation tank 2 and the outer peripheral surface of the mixing chamber 5 by welding or the like. It is good to fix both side edges. Accordingly, the rigidity of the swirl flow preventing member 27 is increased, and the swirl flow can be effectively suppressed.

It is sufficient that at least one swirl-flow preventing member 27 is provided for the coagulation-sedimentation device. However, the above-described coagulation-sedimentation device 1 is provided with four swirl-flow prevention members 27 and each swirl-flow prevention member 27 is provided. 27 is 9 around mixing chamber 5
Mounted at 0 ° intervals. By providing a plurality of swirling flow preventing members in this way, it becomes possible to effectively suppress the swirling flow in a large-sized coagulation settling apparatus. Further, the swirling flow prevention member 27 may be formed of a steel plate, and is effective when it is desired to secure the rigidity of the swirling flow prevention member 27. Further, the swirling flow prevention member 27 has a blowout tube integrated with the mixing chamber, and can be employed in a coagulating sedimentation apparatus in which the mixing chamber itself is rotated.

Next, a procedure for clarifying the liquid to be treated by using the above-described coagulation / sedimentation apparatus 1 will be described. here,
The case where a sludge blanket operation is performed to obtain a clear supernatant will be described with reference to FIG. 5 and the like.

First, the liquid A to be treated is introduced into the mixing chamber 5 through the treatment liquid inflow pipe 6 and the introduction pipe 6a. The additive is injected into the liquid A to be treated in the mixing chamber 5 at any timing from any or all of the injection nozzles 7 provided in multiple stages. As a result, the effect of the additive is maintained for a long time, and an aggregate floc having good sedimentation properties is formed. The liquid A to be treated and the additive in the mixing chamber 5 are stirred by the stirring turbine 8 which is rotationally driven by the turbine driving unit 9a, and the suspended substances and the like in the liquid A to be treated are aggregated to form aggregate flocs ( (Initial floc).

The liquid A to be treated containing the flocculated flocs is distributed and supplied into the sedimentation tank 2 from the blowing pipe 11 of the distributor 10 which is driven to rotate by the driving section 9a. On this occasion,
Of the liquid to be treated A descending from the mixing chamber 5 toward the distributor 10, the mixing chamber 5
The flow of the liquid to be treated A which is going to enter the gap between the fluid A and the distributor 10 is directed inward by the drainage flange 16 forming the seal portion 14 (see FIG. 2).

The flow of the liquid to be treated A which is about to enter the gap between the mixing chamber 5 and the distributor 10 from the side, that is, the flow of the liquid A which is about to enter the gap between the drainage flange 16 and the engaging portion 15. Since the flow of the processing liquid A is blocked by the drain lip 17,
Short circuit of the liquid to be treated A is reliably prevented. Further, the liquid to be treated A that has entered the gap between the drainage flange 16 and the engaging portion 15 is filled with a packing provided between the flange portion 5 a formed on the lower edge of the mixing chamber 5 and the engaging portion 15. 1
9 (see FIG. 2).

As described above, the liquid level height (water pressure) in the mixing chamber 5 and the clarified liquid level (water pressure) in the settling tank 2 are:
Since it can be said that there is almost no change, with such a low-cost and easy-to-construct construction, it is possible to cover the gap between the mixing chamber 5 and the distributor 10 while maintaining the good rotation state of the distributor 10. It is possible to prevent the processing liquid A from being directly discharged. Therefore, the sedimentation / separation efficiency in the sedimentation tank 2 is improved, and a supernatant liquid F having extremely high clarity can be obtained.

The liquid A to be treated containing the flocculated floc is evenly distributed into the settling tank 2 from the outlet 11a of the rotating outlet pipe 11. As a result, a uniform ascending flow is generated in the sedimentation tank 2, and a sludge blanket layer C is formed above the blowing pipe 11. Among flocculated flocs in the liquid A to be treated, those flocculated and separated in the sedimentation tank 2 are stirred by the rake 21 at the lower part of the sedimentation tank 2 to form a concentrated sludge layer D. From the concentrated sludge layer D, the concentrated sludge E is drawn at any time by a sludge drawing pump 24 controlled based on the indicated value of the interface detector, so that the interface height of the sludge blanket layer C is kept within a certain range. Dripping. On the other hand, fine flocs in the upward flow are captured by large flocs of the sludge blanket layer.

On the other hand, the swirling flow generated by the rotation of the blowing pipe 11 collides with the swirling flow preventing member 27 when rising while rotating in the sedimentation tank 2 from the vicinity of the blowing pipe 11. Therefore, the winding of the fine flocculated flocs above the blowing pipe 11 and below the clarified liquid level in the sedimentation tank 2 is suppressed, so that the suspended particle concentration of the supernatant liquid F can be reduced to a desired level. . In addition, the swirl flow prevention member 27
Is stretched in a direction perpendicular to the center axis of the mixing chamber 5, and blocks a space between the inner peripheral surface of the sedimentation tank 2 and the outer peripheral surface of the mixing chamber 5 in the radial direction of the sedimentation tank 2. The member 27 and the swirling flow are substantially orthogonal to each other, and the occurrence of further drift is suppressed. Thereby, the extremely clear supernatant liquid F rises in the sedimentation tank 2 and the clarified layer B is formed. The supernatant F flows out from an outlet 26 provided in the upper part of the sedimentation tank 2.

FIG. 6 is a sectional view showing another embodiment of the seal portion. The seal portion 14A shown in FIG.
Is provided with a draining lip 18. Drip lip 18
Is a ring-shaped plate formed by a steel plate or the like,
The engaging portion 15 is fixed to the outside of the upper edge portion by welding or the like. The lower surface of the drain flange 16 and the upper surface of the drain lip 18 face each other. In this case, the flow of the liquid to be treated which is going to enter the gap between the mixing chamber 5 and the distributor 10 is directed inward by the drainage flange 16 and is also blocked by the drainage lip 18 facing the drainage flange 16. Therefore, the sealing effect can be improved. Note that such a drainer lip 18 may be provided in the seal portion 14 shown in FIG.

The seal portion 14B shown in FIG. 7 fixes the two sheet-like packings 19 to the flange portion 5a formed on the lower edge of the mixing chamber 5 and also has the outer periphery of the engaging portion 15. It is configured to slide on the surface. The seal portion 14C shown in FIG.
The molded packing 19 </ b> A having a U-shape is fixed to a lower portion of the inner peripheral surface of the mixing chamber 5 and is configured to slide on the outer peripheral surface of the engaging portion 15. In any case, the packing 19 or the packing 19A is
5 and may be configured to slide on the inner peripheral surface of the mixing chamber 5. Further, the seal portion may be configured as a grant packing or a mechanical seal.

[0046]

The coagulation and sedimentation apparatus according to the present invention is configured as described above, and thus has the following effects. That is, by providing at least the swirl flow prevention member in the sedimentation tank of the coagulation and sedimentation apparatus, it is possible to realize an agglomeration and sedimentation apparatus capable of obtaining an extremely clarified supernatant.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing a coagulation-sedimentation apparatus according to the present invention.

FIG. 2 is a cross-sectional view showing a seal portion included in the coagulation-sedimentation apparatus of FIG.

FIG. 3 is a perspective view illustrating a configuration of a seal unit.

FIG. 4 is an elevational view showing a swirl flow prevention member included in the coagulation and sedimentation apparatus of FIG. 1;

FIG. 5 is a partial cross-sectional view showing an operation state of the coagulation / sedimentation apparatus of FIG.

FIG. 6 is a cross-sectional view showing another embodiment of the seal portion.

FIG. 7 is a cross-sectional view showing still another embodiment of the seal portion.

FIG. 8 is a cross-sectional view showing another embodiment of the seal portion.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Coagulation sedimentation apparatus, 2 ... Sedimentation tank, 5 ... Mixing chamber, 7 ... Injection nozzle, 8 ... Stirring turbine, 9 ... Center shaft, 10 ... Distributor, 11 ... Outlet pipe,
14, 14A, 14B, 14C ... seal part, 15 ... engagement part, 16 ... drain flange, 17, 18 ... drain lip, 1
9, 19A ... packing, 27 ... swirl flow prevention member, 28 ...
Tube part, 30: wire, A: liquid to be treated, B: clarified layer, C:
Sludge blanket layer, D: concentrated sludge layer, E: concentrated sludge, F: supernatant water.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B01D 21/00-21/34

Claims (6)

(57) [Claims] 1. A liquid mixture and an additive are mixed and stirred in a mixing chamber which is set upright in a sedimentation tank, and the liquid to be treated is supplied to the sedimentation tank from a blowing pipe rotatable around a central axis of the mixing chamber. A coagulation and sedimentation device for clarifying the liquid to be treated by discharging the liquid into the inside of the coagulation / sedimentation tank, and intersecting the central axis at right angles between the inner peripheral surface of the sedimentation tank and the outer peripheral surface of the mixing chamber. A coagulation sedimentation device comprising at least one swirling flow prevention member stretched in a direction. 2. The coagulation sedimentation apparatus according to claim 1, wherein the swirling flow prevention member is formed of a sheet material. 3. The coagulation sedimentation apparatus according to claim 1, wherein the swirl flow prevention member is formed of a steel plate. 4. The swirling flow prevention member is formed as a rectangular sheet having a cylindrical portion at an upper edge and a lower edge, and a wire is inserted into each of the cylindrical portions, and the wire is mixed with the sedimentation tank. The coagulating sedimentation apparatus according to claim 2, wherein the coagulation sedimentation apparatus is installed in the settling tank by being stretched between the chamber and the chamber. 5. The coagulation sedimentation apparatus according to claim 1, wherein a distance between a lower edge of the swirling flow prevention member and the blow-out pipe is 200 mm to 1000 mm. 6. The apparatus according to claim 6, further comprising: four swirling flow prevention members, wherein each of the swirling flow prevention members is rotated by 90 ° around the mixing chamber.
The coagulation sedimentation device according to any one of claims 1 to 5, wherein the coagulation sedimentation device is attached at intervals.