JP2924439B2 - Sludge refining mixing tank - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of adding a flocculant to a slurry sludge discharged from a purification facility for sewage, night soil, industrial waste, clean water and the like, mixing the sludge and flocculating the sludge. The present invention relates to a sludge refining and mixing tank for forming a sludge.

[0002]

2. Description of the Related Art The treatment of sewage discharged from purification facilities such as sewage, human waste, industrial waste, and tap water has been conventionally performed by the following method. That is, the sewage is guided to a sedimentation basin, and in the sedimentation basin, sludge such as earth and sand in the sewage is settled and primary separated. Next, the sewage from which the sludge has been primarily separated is guided to an aeration tank, and the sewage is aerated in the aeration tank. In this way, the aerated sewage is guided to the final sedimentation basin, where the sludge remaining in the sewage is sedimented and separated. Next, the slurry sludge taken out from the final sedimentation basin is led to a temper mixing tank, in which a coagulant is added and mixed into the slurry sludge, and the slurry sludge is coagulated to form flocs. I do. Next, the flocculated sludge is dewatered and then dumped or incinerated.

FIG. 5 is a schematic vertical sectional view of a conventional temper mixing tank, and FIG. 6 is a sectional view taken along line AA of FIG. As shown in FIGS. 5 and 6, the conventional tempering mixing tank 1 is of a cylindrical or square tube type, in which a stirring shaft 3 having a plurality of plate-like stirring blades 2 is rotated. Mounted vertically as possible. The stirring shaft 3 is rotated about its axis by a motor 4 provided outside the tank.

A sludge supply port 5 is provided on the bottom wall 1a of the tempering mixing tank 1.
The coagulant supply port 6 is provided below the side wall 1b. Further, a discharge port 7 for floc sludge is provided in an upper portion of the side wall 1b of the temper mixing tank 1.

The slurry-like sludge a is deposited on the bottom wall of
1a, the flocculant passes through the flocculant supply port 6 provided at the lower part of the side wall 1b of the temper / mixer tank 1 and enters the temper / mixer tank 1 respectively. Supplied. The slurry sludge and the flocculant supplied into the temper mixing tank 1 rise toward the upper part of the temper mixing tank 1 while being mixed and stirred by the rotating stirring blades 2, during which the slurry sludge a Flock b is formed.

[0006] The formed floc b is subjected to a consolidation action by rolling on the inner wall 1c of the temper mixing tank 1, and by this consolidation action, the floc b discharges water contained therein and increases its density. Grow up. The floc b thus grown is discharged out of the tempering mixing tank 1 through the discharge port 7 attached to the upper portion of the side wall 1b.

[0007]

As described above, the density of the floc b is increased by the consolidation effect of rolling the inner peripheral surface 1c of the temper mixing tank 1, thereby increasing the specific gravity of the floc b. Can be increased and its water content reduced. When the inside diameter of the temper mixing tank 1 is small, the area of the tank inner wall occupying a unit volume of the tank is large, so that the probability that the floc b rolls on the inner wall 1c of the temper mixing tank 1 is high.

However, in the case of a large temper mixing tank, the inner diameter of the tank is large, so that the area of the tank inner wall per unit volume of the tank is small. As a result, flock b
However, it is not possible to sufficiently roll the inner wall 1c of the temper mixing tank 1, and therefore, there is a problem that the density of the floc b is reduced.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems and to sufficiently roll the flocks even if the tempering mixing tank is enlarged and the area of the tank inner wall per unit volume of the tank is reduced. Accordingly, an object of the present invention is to provide a sludge refining and mixing tank capable of increasing the density of flocs.

[0010]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems. As a result, the agitating shaft having the agitating blade therein, the agitating blade in the tempering mixing tank in which the agitating blade having the agitating shaft rotatably mounted about the axis thereof is curved outwardly in the rotational direction. A plurality of spiral baffles which are formed in a spiral shape in a direction orthogonal to the rotation axis and, if necessary, are curved on the inner peripheral surface of the refining mixing tank in the rotation direction of the stirring blade. It has been found that if the plates are provided at predetermined intervals, the stirring blades and the baffle plate can act as rolling surfaces of the flocks, and thereby the flocs can be sufficiently rolled.

The present invention has been made on the basis of the above findings. The present invention provides a method for adding a coagulant to sludge, mixing the two, and coagulating the sludge to form flocs.
Inside thereof, a stirring shaft having stirring blades is vertically mounted rotatably about its axis, and is a sludge refining mixing tank, wherein the refining mixing tank is cylindrical and has a lower part. Is formed in a cone shape with a continuously decreasing diameter toward the lower end, and a flocculant supply pipe is connected to the sludge supply port at the lower end.
The agitating blade is formed in a spiral shape in a direction orthogonal to the rotation axis, the outside of which is gently curved in a convex shape toward the rotation direction, and serves as a flock rolling surface .
Further, if necessary, the inner surface of the tempering mixing tank is gently curved toward the rotating direction of the stirring blade to roll the floc.
A plurality of spiral baffle plates that become the surface ,
It is characterized in that it is provided at a predetermined interval.

Next, the temper mixing tank of the present invention will be described with reference to the drawings. FIG. 1 is a schematic vertical sectional view showing a first embodiment of the temper mixing tank of the present invention, and FIG.
FIG. 4 is a cross-sectional view taken along a line A. As shown in FIGS. 1 and 2, the temper mixing tank 8 of the present invention has a cylindrical shape and has a lower portion 8a.
Are formed in a cone shape having a continuously decreasing diameter toward the lower end.

A stirring shaft 3 having a plurality of stirring blades 11 is rotatably mounted vertically in the tempering mixing tank 8, and the stirring shaft 3 is driven by a motor 4 provided outside the tank. It rotates around its axis.

The cone-shaped lower part of the tempering mixing tank 8
A sludge supply port 5 is provided at the lower end of 8a, and a sludge supply pipe 9 is connected to the sludge supply port 5. A coagulant supply port 10 is provided in a portion of the sludge supply pipe 9 adjacent to the sludge supply port 5. At the upper part of the side wall 8b of the temper mixing tank 8, an outlet 7 for the floc sludge is provided.

In the present invention, the stirring blade 11 attached to the stirring shaft 3 has an outer side 11a directed in the rotation direction indicated by the arrow, which is curved gently in a convex shape and spirally extends in a direction perpendicular to the rotation axis. Formed and flock rolling surface
It has become.

[0016]

The slurry sludge a is supplied from the sludge supply port 5 into the temper mixing tank 8 through the sludge supply pipe 9. Then, the coagulant is injected from the coagulant supply port 10 into the slurry sludge passing through the sludge supply pipe 9. The slurry sludge and the flocculant are both supplied from the sludge supply port 5 into the temper mixing tank 8,
Then, they are mixed by the rotating stirring blade 11. Since the lower portion 8a of the refining mixing tank 8 is formed in a cone shape, the rising speed of the slurry sludge and the coagulant supplied therein is fast, and the dead zone is eliminated, and the two are efficiently mixed. Is done. In this way, the slurry sludge aggregates to form flocs b.

As described above, the stirring blade 11 attached to the stirring shaft 3 is formed in a spiral shape in which the outer side 11a directed in the rotational direction is curved in a convex shape. Also serve as the rolling surface of the floc b. Therefore, the floc b formed in the temper mixing tank 8 is:
The inner wall 8c of the mixing tank 8 and the convexly curved outer side of the stirring blade 11
As a result of the rolling of 11a, the density of the floc b is increased by the consolidation effect of the above-described rolling, and the density is increased.

FIG. 3 is a schematic vertical sectional view showing a second embodiment of the temper mixing tank of the present invention, and FIG. 4 is a sectional view taken along line AA of FIG. As shown in FIGS. 3 and 4, the mixing tank 8 according to the second embodiment of the present invention is gently placed on the inner peripheral surface of the mixing tank 8 in the rotation direction of the stirring blade 11 having the above-described structure.
A plurality of spiral baffles for curved plates 1
2 are provided at predetermined intervals and the inner peripheral surface 12a of the baffle plate 12 is also a rolling surface of the floc, which is different from the tempering mixing tank of the first embodiment.

Since the refining mixing tank 8 of the second embodiment is configured as described above, the floc b formed in the refining mixing tank 8 includes the inner wall 8c of the mixing tank 8 and the agitating blades 11. Outer side 11a convexly curved and baffle plate 12
Rolls on the inner side surface 12a. As a result, the density of the floc b is further increased by the consolidation effect of the above-described rolling, and the density is increased.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 3 and FIG.
8 m, a cylindrical shape with a cone-shaped lower part,
A spiral-shaped stirring blade 11 whose outer side 11a in the rotation direction is curved in a convex shape is provided, and a plurality of blades curved in the rotation direction of the stirring blade 11 are provided on the inner peripheral surface of the tank. The coagulant is injected into the slurry-like sewage-mixed sludge passing through the sludge supply pipe 9 using the temper-mixing tank 8 according to the second embodiment of the present invention, which is provided with two spiral baffle plates 12. The slurry sludge and the coagulant in the temper mixing tank 8 were mixed by the rotating stirring blade 11. The coagulant injection rate was 0.6%. The density of the generated floc was high due to the above-mentioned consolidation due to rolling, its specific gravity was 1.10, and its water content after dehydration was 72%.

For comparison, a conventional cylindrical refining and mixing tank 1 having a diameter of 1 m and a height of 1,8 m shown in FIGS. 5 and 6 was used, and a supply provided on a bottom wall 1 a thereof. The same slurry-like sewage-mixed sludge as above is supplied through a port 5, and a supply port 6 provided at a lower portion of the side wall 1b.
The coagulant was supplied through the tank, and the slurry sludge and the coagulant in the temper mixing tank 8 were mixed by the rotating flat stirring blade 2. The coagulant injection rate is 0.6% as above
Met. The density of the formed floc is low due to insufficient rolling, its specific gravity is 1.04, and
The water content after the dehydration was 76%.

As is apparent from the above, when the temper mixing tank 8 of the present invention is used, the specific gravity of the floc is 5% higher than when the conventional temper mixing tank 1 is used. Was reduced by 4%.

[0023]

As described above, according to the present invention,
Even if the tempering mixing tank becomes large and the area of the tank inner wall occupying a unit volume of the tank becomes small, the floc can be sufficiently rolled, so that its specific gravity is increased and the water content after dehydration is reduced. And industrially useful effects.

[Brief description of the drawings]

FIG. 1 is a schematic vertical sectional view showing a first embodiment of a temper mixing tank of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a schematic vertical sectional view showing a second embodiment of the temper mixing tank of the present invention.

FIG. 4 is a sectional view taken along line AA of FIG. 3;

FIG. 5 is a schematic vertical sectional view showing an example of a conventional tempering mixing tank.

FIG. 6 is a sectional view taken along line AA of FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Temper mixing tank 2 Stirrer blade 3 Stirrer shaft 4 Motor 5 Sludge supply port 6 Coagulant supply port 7 Outlet 8 Temper mixing tank 9 Sludge supply pipe 10 Coagulant supply port 11 Stirrer blade 12 Baffle plate A Slurry sludge Flock

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C02F 11/00-11/20 B01D 21/01 B01F 7/00-7/32

Claims (2)

(57) [Claims] 1. A stirring shaft having stirring blades therein for rotating a sludge by adding a flocculant to the sludge and mixing the sludge to form a floc. A sludge refining mixing tank, which is vertically attached to the sludge refining mixing tank, wherein the refining mixing tank has a cylindrical shape, and a lower portion thereof is formed in a cone shape having a continuously small diameter toward a lower end, A flocculant supply pipe is connected to the sludge supply port at the lower end ,
The stirring blade, Nada outer toward the rotational direction in a convex shape
A sludge refining mixing tank, characterized in that the sludge is formed in a spiral shape in a direction perpendicular to the rotation axis and serves as a rolling surface of flock . 2. The inner peripheral surface of the temper mixing tank is gently curved in the direction of rotation of the stirring blade to roll the flock.
A plurality of spiral baffle plates that become the surface ,
The method according to claim 1, which is provided at a predetermined interval.
Sludge refining mixing tank.