JP2001321609A - Settling tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To overflow only a clarified treated water without being accompanied by scum in the treated water. SOLUTION: In a settling tank constituted so that raw water containing a settleable suspended solid is supplied into the tank and the treated water after the suspended solid is settled and separated is discharged outside the tank from an overflow weir, the treated water is taken in from a flow-in port 40 provided in the underwater and opened in the vertical direction, introduced to the overflow weir through a communication passage 42 and discharged from a discharge gutter 36.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sedimentation tank, and in particular, feeds raw water containing a settling suspended substance into a tank, and discharges the treated water obtained by separating and separating the suspended substance from an overflow weir to the outside of the tank. The present invention relates to a sedimentation tank adapted to be discharged.

[0002]

2. Description of the Related Art As a conventional sedimentation tank of this type, a circular one shown in FIG. 6 is well known. The sedimentation tank 10 includes a cylindrical side wall 12 and a bottom part 14 inclined downward toward the center. The upper end of the side wall 12 is formed as an overflow weir 16, and the treated water overflowing from the overflow weir 16 is discharged out of the tank from a ring-shaped drain gutter 18 provided on the upper part of the side wall 12. A cylindrical center well 20 is provided at the center of the tank, and raw water containing a settled suspended substance is supplied into the center well 20. A scraper 24 that is slowly rotated by a motor 22 is disposed at the center of the tank. The scraping machine 24 includes a scraping plate 26 that moves along the bottom portion 14. The scraping plate 26 collects the sediment in the collecting portion 28 at the center of the bottom portion 14, and then discharges the sediment out of the tank. I do.

In this type of sedimentation tank, raw water often contains floating scum called scum. Usually, a means for removing the scum floating on the water surface is provided by a sedimentation tank. It is attached to.

[0004]

However, when the raw water is raw water containing activated sludge obtained by biologically treating sewage, a large amount of scum is generated. In particular, in the case of human wastewater excreted from livestock farms, excessive aeration is performed in the aeration tank in the preceding stage to cope with high-concentration organic matter. Due to this excessive aeration, fine air bubbles adhere to the sludge, and these sludges hardly settle in the sedimentation tank, and float in large quantities as scum. For this reason, it is difficult to deal with the ordinary scum removing means, and there is a problem that the scum overflows from the overflow weir 16 together with the treated water to deteriorate the quality of the treated water.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art. Even when raw water that generates a large amount of scum is supplied, scum does not accompany the treated water and only clear treated water is used. It is an object of the present invention to provide a sedimentation tank which can overflow.

[0006]

In order to achieve the above object, a sedimentation tank according to the present invention supplies raw water containing a sedimentable suspended substance into a tank and precipitates and separates the suspended substance. In a sedimentation tank configured to discharge water from the overflow weir to the outside of the tank, the treated water is introduced below the water surface through an inlet vertically opened, and then guided to the overflow weir. It is characterized by. In the present invention, the vertical direction means a direction substantially perpendicular to the horizontal direction, and specifically, can be interpreted within a range in which a tilt of 30 degrees or less is allowed.

In the sedimentation tank according to the present invention, the inflow port communicates with an overflow portion provided at a water surface position, and the overflow portion is connected to a partition plate that shuts off the water surface in the tank and the inflow port. And an overflow weir for taking in the treated water.

[0008] Further, the sedimentation tank according to the present invention is characterized in that the lower side of the inflow port is protruding outward compared to the upper side.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view showing a main part of a first embodiment of the present invention. The overflow 30 is the side wall 12 of the settling tank.
, And comprises a partition plate 32 for blocking the water surface A in the tank, an overflow weir 34, and a drain gutter 36 integrally provided below the overflow weir 34. A straightening member 38 having a triangular cross section is provided on the side wall 12 below the drain gutter 36 along the side wall 12. The lower end of the partition plate 32 and the tip of the flow regulating member 38 form a vertical opening, and the opening below the water surface serves as an inlet 40 for the treated water. Also,
The outer surface of the drain gutter 36, the inner surface of the partition plate 32, and the rectifying member 38
A region surrounded by the upper surface of the upper surface forms a communication path 42 between the overflow portion 30 and the inlet 40.

In the above configuration, the treated water is supplied to the inlet 40
Then, the water reaches the overflow portion 30 through the communication passage 42, overflows the overflow weir 34, and is discharged to the drain gutter 36. Inflow 40 of treated water
Is an opening in the vertical direction, so that it is unlikely that the scum that floats will flow in from the inflow port 40.

FIG. 2 shows a preferred positional relationship of the inlet 40. As shown in FIG. It is preferable that the inflow port 40 formed by the lower end of the partition plate 32 and the front end 38B of the straightening member 38 has the front end 38B of the straightening member 38 projecting outward by a predetermined dimension L. The scum S floating from below the rectifying member 38 rises along the lower surface 38A of the rectifying member 38 and reaches the tip 38B of the rectifying member 38. Where scum S
Assuming that the ascending speed is V1 and the horizontal inflow speed at the inflow port 40 of the treated water is V2, the scum S rises obliquely in the direction of V3 and reaches the lower end of the partition plate 32. Thereafter, the scum S rises along the outer surface 32A of the partition plate 32 and floats on the water surface A shown in FIG. Therefore, the possibility that the scum S flows from the inflow port 40 to the communication passage 42 side of the treated water is low. Therefore, according to this embodiment, even when raw water that generates a large amount of scum is supplied, scum does not accompany the treated water, and only the clear treated water can overflow from the overflow weir 34. .

If the dimension L is too small, the scum S becomes V
When it rises obliquely in the direction of 3, it becomes easier to flow from the inflow port 40 into the communication passage 42 side of the treated water. When the dimension L is excessively large, the possibility that the scum S flows into the communication passage 42 side is further reduced, but the chance of the sediment C to settle and deposit on the upper surface 38C of the rectifying member 38 is increased, which is preferable. Absent. The upper surface 38C is set so that the sediment C settled on the upper surface 38C of the rectifying member 38 easily slides down along the inclination of the upper surface 38C.
It is preferable to make the inclination angle of the as large as possible. When the inflow velocity V2 in the horizontal direction at the inflow port 40 is high, the scum and suspended matter are more likely to accompany the treated water flowing into the inflow port 40. Therefore, the opening area of the inflow port 40 is designed to be as large as possible to reduce the inflow velocity V2.

The depth of the inlet 40 from the water surface A is
It is preferably an intermediate site between the interface and the precipitate. If the depth from the water surface A to the interface of the sediment is grasped empirically in advance, the depth of the inlet 40 can be easily obtained.

FIG. 3 is a sectional view showing a main part of a second embodiment of the present invention. The overflow portion 44 is provided along the side wall 12 of the sedimentation tank, and includes a partition plate 46 for blocking the water surface A in the tank, an overflow weir 48, and a drain gutter 50 provided outside the overflow weir 48. Consists of One end of a communication pipe 54 is connected to the bottom surface 52 of the partition plate 46. Further, the other end of the communication pipe 54 forms a vertical opening, and the opening below the water surface is an inlet 56 for the treated water. A large number of such communication tubes 54 are connected to the bottom surface 52 of the partition plate 46 at predetermined intervals.

Also in this embodiment, since the inflow port 56 of the treated water is opened below the water surface and in the vertical direction, scum and suspended matter flow into the communication pipe 54 from the inflow port 56 together with the treated water. Unlikely. Therefore, even when supplying raw water that generates a large amount of scum,
The scum does not accompany the treated water, and only the clean treated water can overflow from the overflow weir 48 via the communication pipe 54.

In this embodiment, the end of the communication pipe 54 is formed as a trumpet-shaped inlet 58 as shown in FIG.
It is preferable to adopt a structure in which the lower side of the inflow port 58 protrudes outward compared to the upper side. According to such a structure, the inflow speed of the treated water at the inflow port 58 is reduced.
The scum tends to float upward against the inflow speed of the treated water.
For this reason, the possibility that scum or suspended matter flows into the communication pipe 54 together with the treated water from the inflow port 56 is further reduced.

FIG. 5 is a sectional view showing a main part of a third embodiment of the present invention. The overflow portion 60 is provided at an arbitrary position in the sedimentation tank, and includes a partition plate 62 for blocking the water surface A in the tank, an overflow weir 64, and a drain gutter 66 provided outside the overflow weir 64.
Consists of A communication pipe 70 is provided on the bottom surface 68 of the partition plate 62.
Are connected at one end. The other end of the communication pipe 70 is an inflow portion 72 of the treated water. The inflow portion 72 has a conical upper member 74 and a gap G below the upper member 72.
And a lower member 76 having an inverted conical shape. An opening 78 is provided at a lower end of the lower member 76.

In the above configuration, the portion of the gap G serves as the inflow port 80 of the treated water which is opened in the vertical direction.
The treated water flowing from the inflow port 80 rises in the communication pipe 70, overflows the overflow weir 64 at the overflow section 60, and is discharged out of the tank from the drain gutter 66.

Also in this embodiment, since the inflow port 80 of the treated water is opened below the water surface and in the vertical direction, scum and suspended matter flow into the communication pipe 70 together with the treated water from the inflow port 80. Unlikely. Therefore, even when supplying raw water that generates a large amount of scum,
The scum does not accompany the treated water, and only the clear treated water can overflow from the overflow weir 64 via the communication pipe 70.

In this embodiment, since the inside of the inflow portion 72 is formed in the shape of a large abacus ball, the suspended solids C that have flowed in with the treated water settle inside the inflow portion 72. While moving along the inclined surface of the lower member 76,
It falls from the opening 78. Therefore, it is possible to easily obtain clear treated water, and it is possible to prevent troubles in operation such as suspended substances accumulating and blocking the inflow portion 72 and the communication pipe 70.

Although the above embodiments have been described mainly on the assumption of a circular sedimentation tank, the present invention can also be applied to a square type sedimentation tank. The sedimentation tank according to the present invention can be interpreted in a broad sense within a common sense, and includes a so-called sedimentation tank.

[0022]

As described above, according to the sedimentation tank of the present invention, even when raw water that generates a large amount of scum is supplied, scum does not accompany the treated water, and only clear treated water overflows. Can be washed away.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a preferred positional relationship at an inflow port of the first embodiment.

FIG. 3 is a sectional view of a main part showing a second embodiment of the present invention.

FIG. 4 is a sectional view of a main part showing a modification of the second embodiment.

FIG. 5 is a sectional view of a main part showing a third embodiment of the present invention.

FIG. 6 is a sectional view showing a general structure of a circular settling tank.

[Explanation of Signs] 12 ... side wall 30, 44, 60 ... overflow section 32, 4
2, 62 Partition plate 34, 48, 64 Overflow weir 36, 50, 66 Drain gutter 40, 56, 58, 80 Inlet 42 Communication passage
54, 70 …… Communication pipe

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Katsumi Shida 1-1-1 Uchikanda, Chiyoda-ku, Tokyo Inside Hitachi Plant Construction Co., Ltd.

Claims (3)

[Claims] In a sedimentation tank, raw water containing a suspended solid is supplied into a tank, and treated water obtained by separating and separating the suspended substance is discharged from an overflow weir to the outside of the tank. A sedimentation tank, wherein water is introduced from an inflow port provided below the water surface and opened in a vertical direction, and then guided to the overflow weir. 2. The inflow port communicates with an overflow portion provided at a water surface position. The overflow portion is a partition plate for shutting off the water surface in the tank and an overflow of the treated water introduced from the inflow port. The sedimentation tank according to claim 1, further comprising a weir. 3. The sedimentation tank according to claim 1, wherein a lower side of the inflow port projects outward compared to an upper side.