JPS60150807A - Settling tank - Google Patents

Abstract

PURPOSE:To obtain concentrated sludge of high concentration by constructing a stirring blade with a net material to prevent generation of bridge without disturbing the flow of the sludge. CONSTITUTION:Filthy water contg. sludge is fed from a feed pipe 3. The direction of the flow is once deflected upward by a feeding port 15, but is straightened thereafter in a flow straightening cylinder 4. The raised water, i.e. the water to be treated flows over an overflow weir 2 and is gathered in a discharging groove 5 and is discharged to the outside of the system from an outlet port 6. On one hand, the sludge is stirred during settling by the stirring blade 13, splitted finely by the net material 14 in the vertical, and horizontal direction and also in the composite direction. Thus, upward passage of water flow is secured, and formation of bridge by the sludge particles with each other is eliminated. Further, the dispersed sludge gathers again and settles as sludge of high concn. The sludge settling to the bottom surface of the settling tank 1 is collected by a sludge collecting blade 12 and is withdrawn to the outside from a discharge pipe 8.

Description

[Detailed description of the invention] This invention relates to a settling tank.

Sedimentation tanks are used, for example, to separate water from sludge produced by biological treatment of sewage. Therefore, in such a settling tank, the performance of separating sludge and water is of course extremely important.

That is, if the sedimentation and separation of sludge is not performed well, the sludge will flow out of the sedimentation tank together with the treated water, and the treatment performance will not improve. Furthermore, since the concentration of sludge that is sedimented and concentrated becomes low, the amount of sludge that is drawn out increases, which not only increases the power cost of the drawing pump but also increases the cost of sludge treatment such as incineration.

Conventionally, as a sedimentation tank, a vibrator, an angle, a round bar, or other bits are attached vertically and in the form of a fence to a sludge collector installed inside the tank, and these are rotated together with the sludge collector to gently collect the sludge. A so-called settling tank with pickets is known, in which the sludge is separated by sedimentation by stirring the water to promote the rise of the water. However, such conventional settling tanks have drawbacks as explained below.

In other words, since the above-mentioned conventional settling tank uses the above-mentioned bucket as a so-called stirring blade, it is not possible to cut the sludge in the settling tank into concentric cylinders and stir it to ensure an upward flow path for water. Even if it is possible, the sludge becomes nY and is stirred,
Concentration efficiency is low because it is difficult to eliminate cross-linking between sludges and the stirring action only affects almost the same area. When stirring is performed uniformly over a wide area and the pickets are placed densely in an attempt to eliminate crosslinking,
Since the gaps between the buckets become smaller, a sludge co-rotation phenomenon occurs, and strong agitation disturbs the flow of the entire sludge, and in either case, the concentration efficiency does not improve.

An object of the present invention is to provide a settling tank that can solve the above-mentioned drawbacks of conventional devices, can prevent the occurrence of crosslinking without disturbing the flow of sludge, and can obtain thickened sludge with a high fA degree. It is in.

In order to achieve the above object, the present invention includes a tank body, a sewage supply part provided in the center of the tank body, a treated water discharge part provided in the peripheral part of the tank body, and a A settling tank is provided, which has a sludge drawing part provided at the bottom and a stirring blade rotatably provided in the tank body, and the stirring blade is formed of a net member.

To explain one embodiment of the sedimentation tank of this invention, FIG.
In the schematic front view including a sectional view), 1 is a tank body. This tank body 1 has a circular shape as a whole, but its bottom part is formed into an inverted conical shape. In the center of the tank body 1, there is a sewage supply section consisting of a rectifier tube 4 and a supply pipe 3 having an upward supply port 15, and in the periphery, there is an overflow weir 2, a discharge groove 5, and a discharge port 6. A treated water discharge section and a sludge extraction section having a withdrawal lower and a withdrawal pipe 8 are provided at the bottom. Further, inside the tank body 1, a drive shaft 10 is provided.
A set of stirring blades 1 driven by a motor 11 via
3 is provided. This stirring blade 13 has a rope member 14 extending over the frame body 9. The net member 14 is made of a perforated metal or plastic plate, a woven or knitted fabric of metal or relatively thick synthetic fiber, and has a large number of square, rectangular, triangular, hexagonal, circular, and oval shapes. Further, a mud collecting blade 12 made of metal, plastic, rubber, etc. is attached to the lower part of the frame 9. In addition,
The stirring blade 13 has an upper end 0.1 to 0.1 m below the liquid level of the settling tank.
It is installed at a height of 2 m, preferably 0.5 to 1.5 m.

To explain the operation of the sedimentation tank described above, sewage containing sludge is supplied from the supply pipe 3, and after being changed into an upward flow by the supply port 15, the flow is adjusted in the rectifying tube 4, and is then directed downward. Flowing down to J: Flowing down. However, since there is a difference in specific gravity between sludge and water, the sludge gradually settles in the process of flowing down, and the sewage changes its flow upward. The rising water, that is, the treated water, passes through the overflow weir 2, is collected in the discharge groove 5, and is discharged from the system through the discharge port 6.

On the other hand, the sludge increases its concentration as it further settles, but in the process it is stirred by the stirring blades 13 and cut into thin pieces by the net member 14 in the vertical direction, horizontal direction, or a combination thereof in FIG. The water flow path towards the sludge is secured, and the crosslinks between the sludge are eliminated.
Furthermore, the sludge gathers again and settles as highly concentrated sludge.

The sludge that has reached the bottom of the settling tank 1 is collected by the sludge collecting blade 12 in the lower drawer and drawn out of the system through the drawing pipe 8. Note that the rotational speed of the stirring blade 13 is 0.02 to 10
The rotation/min and circumferential speed are adjusted to about 0.3 m/sec.

Furthermore, various flocculants may be added to the sedimentation tank during operation.

In the embodiment described above, it is preferable that the mesh member has a diameter of 60 to 1000 mm in terms of circumferential length. More preferably 200 to 600 mn
It is +. Also, the thickness of the legs forming the eyes is 0.
It is preferably about 5 to 3QllllIl. Further, the porosity of the net member is preferably 80% or more.

More preferably, it is 90% or more. In short, it is preferable that the mesh member has as small a mesh as possible without causing sludge rotation or disturbing the overall flow of the sludge, the mesh member forming the mesh is thin, and the opening ratio is high. However,
The net member may be stretched flat over the entire frame as shown in FIG. 1, or may be stretched over a part of the frame as shown in FIG. It's good. When spreading the net over a part of the frame, change the type and size of the net material in each part, or change the spreading position so that the stirring blades are aligned with the axis 1.
It may be configured to be asymmetric with respect to 0. Also,
As shown in Fig. 3, a large number of net members, so-called units, are attached to the frame at an angle to the plane they form to form three-dimensional stirring blades. It's okay. Furthermore, in Figure 1, there are only 11 stirring blades.
'], but multiple sets of stirring blades may be provided.

FIG. 4 shows a settling tank of a different embodiment from that shown in FIG. 1 above. In the sedimentation tank of this embodiment, the sewage supply port 15 in the embodiment of FIG.
The flocculation tank 17 is opened into the flocculation tank 17.
A coagulation stirrer 18 coupled to a drive shaft 10 is provided in 7,
Furthermore, a number of concentric inverted conical guide plates are provided above the stirring blades 13 to guide the sludge and promote its settling. The sedimentation tank of the present invention may be such a so-called coagulation sedimentation tank.

The sedimentation tank of the present invention as described above can be used for various purposes. For example, it is used to separate sludge and water produced by various sewage treatments such as the activated sludge method, rotating disk method, trickling filter method, and contact oxidation method, which are known as biological sewage treatment methods, as well as other sewage treatments. can do. Furthermore, it can be used for solid-liquid separation in various manufacturing industries, such as paper pulp manufacturing, food manufacturing, sake brewing, and miso brewing, and for recovery of valuables in chemical processes.

As explained above, in the settling tank of the present invention, since the stirring blades are constructed of a net member, the net member allows the sludge to be moved vertically, horizontally, or in a combination thereof without disturbing the overall flow. Not only can crosslinking of sludge be prevented, but also retained water between sludge can be well separated, and small but dense and highly concentrated sludge can be obtained. Therefore, while the quality of the treated water is improved, the amount of sludge m to be drawn out is also reduced, and not only the power required for sludge usage can be reduced, but also the cost of sludge treatment such as incineration can be significantly reduced.

In addition, due to local agitation by the net members, gases such as nitrogen generated in the tank rise smoothly and are degassed, so sludge is not entrained by these gases and scum is not formed. . Furthermore, since the stirring is performed microscopically, drifting in the tank is less likely to occur, and sludge deterioration and decay due to abnormal stagnation are also prevented.

[Brief explanation of drawings]

FIG. 1 is a schematic front view including a sectional view of an embodiment of the sedimentation tank of the present invention, and FIG. 2 is a schematic diagram showing a different aspect from the above-mentioned FIG. 1 of the stirring blade used in the present invention. A front view, FIG. 3 is a schematic perspective view showing a stirring blade in a further different embodiment, and FIG. 4 is a schematic diagram including a sectional view showing the settling tank of the present invention in an actual M embodiment different from that in FIG. 1 above. It is a front view. 1: Tank body 2: Overflow weir 3: Supply pipe 4: Straightening cylinder 5: Discharge groove 6: υ1 output lower: Pull-out port 8: Pull-out pipe 9: Frame 10: Drive shaft 11: Motor 12: Sludge collection blade 13 : Stirring blade 14: Net member 15: Supply port 16: Supply port/medicine spout 17: Coagulation tank 18: Coagulation stirrer 19: Guide plate Patent applicant Toshi Co., Ltd. Figure 2 Figure 3 β

Claims (1)

[Claims] a tank body, a sewage supply part provided in the center of the tank body, a treated water discharge part provided in the peripheral part of the tank body, a sludge extraction part provided in the bottom part of the tank body, and a sludge extraction part provided in the bottom part of the tank body; What is claimed is: 1. A settling tank comprising a rotatably provided stirring blade, the stirring blade comprising a net member.