JP2006272253A - Sedimentation tank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sedimentation tank relating to the sedimentation tank (precipitation equipment) for settling to separate raw water and excellent in solid-liquid separation efficiency. <P>SOLUTION: The raw water is supplied in a field well 12, mainly flows in a radial direction, then rises along the inside perimeter wall face 11b of a tank body, overflows an overflow dam 15 and is discharged from a clarified water discharge pipe 16. A flocculent overflows from a downward overflow hole 14a of a pipe 14 placed circumferentially along the inside perimeter wall face 11b of the tank body. Since the flocculent is uniformly loaded into water rising along the inside perimeter wall face 11b, sedimentation treatment is efficiently carried out. A sediment flows from the inside perimeter wall face 11b along the bottom face 11a of the tank body, flows into a pit-like discharge part 13 and is discharged outside the tank body 11 from there. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sedimentation tank (sediment separation apparatus) for subjecting raw water to sedimentation separation, and in particular, at least part of the raw water supplied into the tank body rises along the inner wall surface of the tank body to become clarified water, The present invention relates to a sedimentation tank configured so that the clarified water flows out from the overflow portion. More specifically, the present invention relates to a precipitation tank in which a flocculant is added to water in the precipitation tank through a pipe having a plurality of flocculant outflow holes in the longitudinal direction.

  A sedimentation tank in which a feed well is arranged at the center of a circular tank body, an overflow weir is provided at the upper part of the inner periphery of the tank body, and the clarified water is taken out from the overflow weir. Is well known.

In JP-A-7-80211, a mixing section is provided in this feed well section, suspension water and a flocculant as water to be treated are introduced into the mixing chamber, mixed by a mixer to obtain a mixed solution, and the mixing chamber A coagulating sedimentation apparatus is disclosed in which a mixed solution flows into a sedimentation tank through a plurality of holes provided in a pipe extending from the lower end of the sedimentation tank.
Japanese Patent Laid-Open No. 7-80211

  When a mixing chamber is provided in the settling tank as described in JP-A-7-80211, it is necessary to increase the volume of the settling tank, and a large installation space is required. In addition, there is a problem that it is necessary to provide a mixer in the center, which requires a large installation cost.

  An object of the present invention is to provide a sedimentation tank in which a flocculant is reliably supplied to raw water to be subjected to sedimentation separation and is excellent in solids sedimentation separation characteristics.

  In the sedimentation tank of the present invention (Claim 1), at least a part of the raw water supplied from the raw water supply section into the tank body rises along the inner wall surface of the tank body, and from the overflow section at the top of the tank body. The settling tank that flows out as clarified water is characterized by comprising a pipe provided with a flocculant outflow hole that is submerged in the settling tank.

  The sedimentation tank according to claim 2 is the sedimentation tank according to claim 1, wherein the pipe is provided with a plurality of flocculant outflow holes at intervals in the longitudinal direction, and the pipe is provided between the raw water supply unit and the inner wall surface. It is characterized by being provided substantially horizontally.

  A sedimentation tank according to claim 3 is characterized in that, in claim 2, the pipe is extended from the raw water outlet of the raw water supply section toward the inner wall surface and in a crossing direction.

  A sedimentation tank according to claim 4 is characterized in that, in any one of claims 1 to 3, a feed well for raw water supply is installed as the raw water supply section at the center of the tank body, and an upper part of the inner wall surface of the tank body. The overflow portion is provided, and the pipe is provided around the feed well.

  The precipitation tank according to claim 5 is characterized in that, in claim 4, the pipe is provided around the wall surface of the tank body between the overflow portion and the bottom surface of the tank body. .

  The sedimentation tank of claim 6 is characterized in that, in claim 4, the pipe circulates around the raw water outlet at the lower end of the feed well.

  The sedimentation tank according to claim 7 is the precipitation tank according to any one of claims 1 to 3, wherein the tank body has a square planar shape, the raw water supply unit is provided on one end side of the tank body, and the other tank body. The overflow portion is provided on the upper side of the end side, and the pipe extends in a tank body width direction substantially orthogonal to a direction connecting the one end side and the other end side of the tank body. It is characterized by.

  The sedimentation tank according to claim 8 is characterized in that, in claim 7, the pipe is provided along the wall surface of the tank body on the other end side between the overflow portion and the bottom surface of the tank body. Is.

  The sedimentation tank of claim 9 is characterized in that, in claim 7, the pipe is provided in the vicinity of the raw water supply section.

  A sedimentation tank according to claim 10 is characterized in that, in any one of claims 1 to 9, the outflow hole of the pipe is provided on a lower surface of the pipe.

  In the precipitation tank of the present invention, for example, when a feed well is provided at the center of the tank body, most of the raw water supplied to the feed well flows radially from the feed well toward the wall surface of the tank body, It rises along the inner wall surface, and during this time, solids are settled and separated, and the clarified water overflows the overflow portion at the upper part of the tank body.

  When the sedimentation tank of the present invention is a square tank, the raw water is supplied to the raw water supply section on one end side of the tank, flows toward the other end side of the tank, and then rises along the inner wall surface of the tank body, Minute sedimentation treatment is performed, and clear water overflows the overflow part at the upper part of the tank body.

  In the settling tank of the present invention, a pipe provided with a flocculant outflow hole is provided in the settling tank, and in order to add the flocculant directly into the tank body, the raw water and the flocculant are efficiently added by the flow in the tank body. And are mixed.

  Further, in the sedimentation tank of the present invention, a flocculant addition pipe is provided in the cross direction with the flow direction in the raw water tank, or agglomerates from a plurality of holes provided in the pipe at intervals in the longitudinal direction. When the agent is allowed to flow out, the flocculant is uniformly added to the raw water, and the solids separation efficiency is improved.

  In the present invention, when the flocculant addition pipe is provided along the wall surface of the tank in which the water to be treated rises, the flocculant is added to the water to be treated that rises along the wall surface of the tank. Solids rising with water are efficiently aggregated.

  By providing the flocculant addition pipe so as to surround the feed well in the vicinity of the feed well, the flocculant can be uniformly added to the raw water.

  In addition, in the square tank, the flocculant is uniformly added to the raw water even when the flocculant addition pipe is extended in the tank width direction in the vicinity of the raw water supply section.

  As the flocculant, a polymer flocculant is suitable. Since this flocculant solution has a specific gravity greater than that of water, providing the flocculant outflow hole on the lower surface of the pipe allows the flocculant to smoothly flow out of the pipe.

  Hereinafter, preferred embodiments of the present invention will be described. 1 (a) is a longitudinal sectional view of a sedimentation tank according to an embodiment, FIG. 1 (b) is an enlarged view of a part of FIG. 1 (a), and FIG. 2 is a sectional view taken along the line II-II in FIG. FIG.

  In the sedimentation tank 10 according to this embodiment, the tank body 11 is circular, and the feed well 12 is installed at the center thereof. The feed well 12 has a cylindrical shape whose upper and lower ends are open, and the upper end of the feed well 12 protrudes upward from the water level in the tank body 1. The lower end of the feed well 11 is a raw water outlet, and a circular plate 12a is provided so as to face the lower end surface of the feed well 12 so that the raw water flow direction from the raw water outlet is a horizontal radial direction.

  A pit-shaped discharge portion 13 is provided at the center bottom of the tank body 1 for collecting and discharging the settled solid content.

  The bottom 11a of the tank body 11 has a conical shape with a downward gradient from the inner peripheral wall surface 11b of the tank body 11 toward the center. In this embodiment, a rake 17 for scraping the sediment rotating along the bottom portion 11a is provided. In some cases, the bottom can be made flat by devising the mud collecting rake structure, but the shape of the bottom is not particularly limited.

  An overflow weir 15 as an overflow portion is provided along the upper portion of the inner peripheral wall surface 11 b of the tank body 11.

  Along the inner peripheral wall surface 11b, a flocculant addition pipe 14 made of a pipe having a circular cross section extending in the circumferential direction is provided between the tank bottom 11a and the overflow weir 15. A plurality of coagulant outflow holes 14 a are provided on the lower surface of the pipe 14 at intervals in the longitudinal direction. The pipe 14 makes one round of the inner periphery of the tank body 11 and is supported by the tank body 11 by a support member (not shown). In this embodiment, only one pipe 14 is provided, but a plurality of pipes 14 may be provided.

  A suitable position of the pipe 14 will be described with reference to FIG.

Water depth _{H 1} of the peripheral wall portion of the tank body 11 is preferably about 100~400cm particularly 150～250Cm. Depth of _{H 2} pipe 14 is preferably about 50~350cm particularly 100～250Cm. Preferably the pipe water depth H ₂ is the difference between the lower end of the depth of the feed well 12 is within particularly 50cm within 100 cm, especially preferably located at the lower end the pipe 14 and is substantially the same depth of the feed well 12.

  The inner diameter of the pipe 14 is preferably about 2 to 10 cm. The arrangement pitch of the holes 14a in the longitudinal direction of the pipe 14 is preferably about 1 to 15 cm, particularly about 2 to 10 cm.

  The inner diameter of the hole 14a is preferably selected so that the linear velocity of the flocculant from the hole 14a is 10 to 100 cm / sec, particularly 20 to 50 cm / sec.

  The distance D between the pipe 14 and the inner wall surface 11b is preferably 100 cm or less, particularly 15 to 50 cm.

  In the sedimentation tank 10 configured in this way, raw water is supplied into the feed well 12, flows out from between the lower end of the feed well 12 and the plate 12a, flows in a radial direction toward the peripheral wall surface 11b in the tank, and then It rises along the inner wall surface 11 b, overflows the overflow weir 15, and is discharged from the clarified water discharge pipe 16.

  The flocculant is added from the pipe 14 to the water that has reached the inner peripheral wall surface 11b of the tank. Since the pipe 14 is provided with holes 14a in the entire region in the longitudinal direction, the flocculant is uniformly added to all the water reaching the inner wall surface 11b. For this reason, solid content settles efficiently. The sediment flows from the inner peripheral wall surface 11b along the tank body bottom surface 11a, flows into the pit-shaped discharge part 13, and is discharged from the tank body 11 from here.

  In the above embodiment, the pipe 14 is horizontal, but may be slightly inclined, or may be a spiral shape along the inner peripheral wall surface 11b.

  In the above embodiment, the tank body 11 has a circular shape in plan view, but may be rectangular like the tank body 10B of FIG. 3B, and may be a polygon more than a pentagon, an ellipse, or the like. May be. 14B shows the flocculant addition piping.

  In the above embodiment, the pipe 14 has an annular shape along the inner peripheral surface of the tank body 11 as shown in FIG. 2, but is a hexagonal pipe 14A like the settling tank 10A in FIG. Alternatively, it may be a polygon such as a quadrangle, pentagon, heptagon, or octagon (not shown). However, as shown in FIGS. 1 and 2, an annular shape is preferable because of high separation efficiency.

  In the present invention, a flocculant addition pipe 14 ′ may be provided so as to surround the outer periphery of the raw water outlet between the lower end of the feed well 12 and the plate 12 a as in the sedimentation tank 10 </ b> C of FIG. 4. A plurality of flocculant outflow holes 14a (not shown in FIG. 4) are also provided on the lower surface of the pipe 14 'at intervals in the longitudinal direction.

  The distance between the outer peripheral surface of the feed well 12 and the pipe 14 'is preferably 100 cm or less, particularly 10 to 50 cm.

  As described above, even when the pipe 14 ′ is provided close to the feed well 12, the flocculant is uniformly added to the raw water, and the sedimentation process is efficiently performed.

  Both the pipe 14 and the pipe 14 'may be provided.

  A sedimentation tank 20 according to another embodiment will be described with reference to FIG. 5 (a) is a longitudinal sectional view in the longitudinal direction of the settling tank 20, FIG. 5 (b) is a plan view of the settling tank 20, and FIG. 5 (c) is an enlarged view of a part of FIG. 5 (a). FIG.

  The tank body 21 of the sedimentation tank 20 has a rectangular shape in plan view, and a raw water supply section is formed by a drooping wall 22 that is suspended along one end side (front end wall) 21a in the longitudinal direction. The hanging wall 22 extends in the tank body 21 in a direction parallel to the front end wall 21 a and crosses the tank body 21.

  The lower end of the hanging wall 22 is higher than the bottom surface of the tank body 21. Below the tank body 21, a horizontal wall 22a projecting horizontally from the front end wall 21a is disposed. Raw water flows between the lower end of the drooping wall 22 and the horizontal wall 22a and flows in the tank body 21 toward the other end side (rear end wall) 21b in the longitudinal direction. The horizontal wall 22a extends to the rear end wall 21b rather than the hanging wall 22.

  The bottom surface of the tank body 21 has a downward slope from the rear end wall 21 b toward the front end wall 21 a, and a sludge pit 23 is provided below the hanging wall 22.

  An overflow weir 25 is provided in the upper part of the rear end wall 21b. The overflow weir 25 is provided so as to cross the tank body 21 in the lateral direction.

  Between the overflow weir 25 and the bottom surface 21c of the tank body 21, a flocculant addition pipe 24 is provided along the rear end wall 21b. The pipe 24 is a straight tube that crosses the tank body 21 in the lateral direction. A flocculant outflow hole 24 a is provided on the lower surface of the pipe 24 at intervals in the longitudinal direction of the pipe 24. The preferred arrangement and diameter of the holes 24a are the same as those of the holes 12a.

Water depth H ₄ of the pipe 24 shown in FIG. 5 (c) are either horizontal wall 22a and the same level, it is preferable to position the upper or lower within a range of 100cm Rather, in particular horizontal wall 22a at the same level It is preferable that

Incidentally, water depth _{H 3} in the rear end wall 21b is preferably about 100～400Cm.

  In this embodiment, only one pipe 24 is provided, but a plurality of pipes 24 may be provided substantially in parallel. In the case where a plurality of pipes 24 are provided in parallel, they may be arranged adjacent to each other in the vertical direction or may be arranged horizontally next to each other.

  In this embodiment, a pipe 24 ′ having the same configuration as the pipe 24 crossing the tank body 21 in the short direction is provided on the horizontal downstream side of the raw water outlet between the lower end of the drooping wall 22 and the horizontal wall 22 a. Also good. Only one of the pipes 24, 24 'may be provided, or both may be provided. A plurality of pipes 24 'may be provided.

  In the sedimentation tank 20 configured in this manner, raw water is supplied into the tank body 21 from between the front end wall 21a and the hanging wall 22, and passes between the lower end of the hanging wall 22 and the horizontal wall 22a to form the tank body 21. The inside flows toward the rear end wall 21b, and a part of the solid content settles during this time. The raw water hitting the rear end wall 21b then rises along the rear end wall 21b. At this time, the solid content is separated, and the clarified water gets over the overflow weir 25 and is taken out of the tank body 21.

  When the raw water rises along the rear end wall 21 b, the solid content in the raw water separates from the rising flow and settles on the bottom surface 21 c of the tank body 21. The solid content settled on the bottom surface 21 c flows down on the bottom surface 21 c toward the pit 23 and is discharged out of the tank body 21 from the pit 23.

  In this embodiment, the flocculant is added from the pipes 24 and / or 24 ′ to the water flowing in the tank body 21 in this way. Since the pipes 24 and 24 'are provided with a plurality of holes 24a in the longitudinal direction, the flocculant is uniformly added to the water to be treated, and the solid-liquid separation efficiency is improved. The solid content concentration is sufficiently low.

  In the above embodiment, the pipes 24, 24 'are provided horizontally, but may be slightly inclined.

  The present invention can be used for a sedimentation tank in various processes in addition to wastewater treatment.

FIG. 1 (a) is a longitudinal sectional view of a sedimentation tank according to an embodiment, and FIG. 1 (b) is a partially enlarged view of FIG. 1 (a). It is the II-II sectional view taken on the line of FIG. It is a horizontal sectional view of the tank concerning another embodiment. It is a longitudinal cross-sectional view of the tank which concerns on another embodiment. 5 (a) is a longitudinal sectional view in the longitudinal direction of the settling tank 20, FIG. 5 (b) is a plan view of the settling tank 20, and FIG. 5 (c) is an enlarged view of a part of FIG. 5 (a). FIG.

Explanation of symbols

10, 10A, 10B, 10C, 20 Sedimentation tank 11, 21 Tank body 11b Circumference wall surface in body 12 Feed well 14, 14A, 14B, 24, 24 'Flocculant addition pipe 14a, 24a Outflow hole 15, 25 Overflow weir 22 Hanging wall 22a Horizontal wall

Claims (10)

In a sedimentation tank in which at least part of the raw water supplied from the raw water supply part rises along the inner wall surface of the tank body and flows out as clarified water from the overflow part at the top of the tank body,
A settling tank comprising a pipe provided with a flocculant outflow hole submerged in the settling tank.   In Claim 1, the said piping is provided with the some flocculent outflow hole at intervals in the longitudinal direction, and this piping is provided substantially horizontally between the said raw | natural water supply part and the said inner wall surface. A sedimentation tank characterized by that.   The sedimentation tank according to claim 2, wherein the pipe extends in a direction crossing the direction from the raw water outlet of the raw water supply unit toward the inner wall surface. In any 1 item | term of the Claims 1 thru | or 3, the feed well for raw | natural water supply is installed as the said raw | natural water supply part in the center part of the said tank body, and the said overflow part is provided in the upper part of the inner wall surface of this tank body. And
The sedimentation tank, wherein the pipe is provided around the feed well.   5. The sedimentation tank according to claim 4, wherein the pipe is provided around the wall surface of the tank body between the overflow portion and the tank bottom surface.   5. The sedimentation tank according to claim 4, wherein the pipe circulates around a raw water outlet at a lower end of the feed well. In any one of Claims 1 thru | or 3, the planar shape of the said tank body is a square,
The raw water supply part is provided on one end side of the tank body,
The overflow portion is provided in the upper part of the other end side of the tank body,
The said piping is extended in the tank width direction substantially orthogonal to the direction which connects this one end side and other end side of this tank body, The sedimentation tank characterized by the above-mentioned.   8. The sedimentation tank according to claim 7, wherein the pipe is provided along a wall surface of the tank body on the other end side between the overflow portion and the bottom surface of the tank body.   In Claim 7, The said piping is provided in the vicinity of the said raw | natural water supply part, The sedimentation tank characterized by the above-mentioned.   The sedimentation tank according to any one of claims 1 to 9, wherein the outflow hole of the pipe is provided on a lower surface of the pipe.

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