JP6536657B2 - Settling tank - Google Patents

Description

  The present invention relates to a settling tank for settling and separating sludge, and more particularly to a settling tank in which water to be treated is supplied to the lower portion of the settling tank via a center well.

  Conventionally, in activated sludge treatment facilities, coagulation sedimentation treatment facilities, etc., sedimentation separation using a solid-liquid separation tank (precipitation tank) is generally used as a means for separating the sludge mixed liquid (coagulation treatment liquid) into treated water and sludge. It is adopted. In this sedimentation separation, a sludge zone (sludge blanket layer) is formed in the sedimentation tank in order to efficiently remove suspended solids and fine SS in the sludge mixed liquid to obtain good treated water, and The sludge blanket filtration system is used to filter and separate suspended solids and fine SS in the sludge mixed solution by passing the sludge mixed solution from the lower part of this sludge zone through the feed well and passing through the sludge zone. There is.

  It is known that a plate is provided horizontally as opposed to the lower end of the center well in the central portion of the tank body as a center well type settling tank, and the flow direction of the effluent water from the center well is changed in the radial direction. (Patent Document 1).

  In order to effectively perform solid-liquid separation in the sedimentation tank and obtain highly-clear treated water in the coagulation / sedimentation apparatus, it is important to introduce the produced flocculated flocs into the sedimentation tank without breaking it. That is, when the flocculated floc is broken down and refined, its sedimentation property deteriorates, and it flows out to the treated water side to deteriorate the water quality of the treated water.

  In Patent Document 2, a cylindrical inflow portion having a diameter larger than that of the center well is formed in the upper portion of the cylindrical center well, and the aggregation treated water is supplied from the inflow pipe in the tangential direction of the peripheral wall of the inflow portion. At the inflow portion, a swirling flow is formed along the peripheral wall, and introduced into the center well as it is to form a downward flow while swirling in the center well, thereby generating turbulent flow when introducing coagulation treatment water. It is disclosed to prevent and inhibit the destruction of the flocculated floc.

  When the tank body is cylindrical, the flocculated treated water which descends while swirling the center well flows out into the tank while forming a swirling flow, and as it swirls in the tank as it is, the uniform upward flow causes sedimentation separation. I do. However, when the plan view shape of the tank is a square, the upward flow is different between the corner far from the center well and the center of the wall near the center well (central part in the side direction). Formation of uniform upward flow is inhibited.

JP 2005-66533 A JP 2017-87090 A

  An object of the present invention is to provide a settling tank which can introduce the water to be treated into the center well while stopping its swirling.

  In the settling tank of the present invention, the water to be treated supplied from the center well at the central portion of the tank body to the lower portion inside the tank body rises in the tank body and becomes clear water from the overflow portion at the top of the tank body. And a center well upper member forming an annular water channel at the top of the center well, and the water to be treated is introduced into the annular water channel by the introduction member in the circumferential direction along the peripheral wall In the settling tank introduced into the center well, the upper portion of the center well is provided with a pivot stop member for stopping pivoting of the water to be treated.

  In one aspect of the present invention, the turn stopping member is formed of a plurality of plates extending in the centripetal direction from the inner circumferential surface of the center well, the plate surfaces being in the vertical direction.

  In one aspect of the present invention, the width in the centripetal direction of the plate is 5 to 20% of the inner diameter of the upper portion of the center well.

  In one aspect of the present invention, the turning stop member is a plate disposed in two orthogonal directions with the plate surface in the vertical direction.

  In one aspect of the present invention, the pivoting stop member is composed of a plurality of cylinders or columns extending in the vertical direction.

  In one aspect of the present invention, the pivot stop member is detachably attached to the center well.

  In one aspect of the present invention, a plate is provided to face the lower end of the center well to change the flow direction of water.

  In one aspect of the present invention, the tank body has a rectangular shape in a plan view.

  According to the present invention, even when operating at a high LV in a square sedimentation tank, the formation of non-uniform upward flow in the sedimentation tank is suppressed while suppressing the destruction of aggregated floc when flowing into the center well And the treated water SS can be lowered. That is, in the sedimentation tank of the present invention, the water to be treated that has flowed into the annular water channel in the circumferential direction flows into the center well while forming a swirling flow in the annular water channel. Since the turning stop member is provided on the upper inner circumferential surface of the center well, the water to be treated is lowered without turning in the center well. Therefore, even if the tank body is rectangular, inhibition of uniform upward flow can be suppressed in the sedimentation tank, and sludge can be efficiently separated.

It is a longitudinal cross-sectional view of the sedimentation tank which concerns on embodiment. It is a top view of the sedimentation tank of FIG. It is a perspective view of the center well upper part of the sedimentation tank of FIG. (A) is a top view of the center well of the sedimentation tank which concerns on another embodiment, (b) is a perspective view of a rotation stop member. It is a top view of the rotation stop member which concerns on another embodiment. It is a top view of the rotation stop member which concerns on another embodiment. It is a top view of the rotation stop member which concerns on another embodiment. It is a top view of the rotation stop member which concerns on another embodiment.

  Hereinafter, embodiments will be described with reference to the drawings. 1 to 3 show a settling tank according to the first embodiment.

  In the sedimentation tank according to this embodiment, the tank body 1 is a quadrangle (a square such as a square). A center well 2 is installed at the center of the tank body 1. The center well 2 has a cylindrical shape with open upper and lower ends.

  A center well upper 3 having a diameter larger than that of the center well 2 is provided on the top of the center well 2 as a center well upper member. The center well upper 3 is connected to the upper end portion of the center well 2 and has a flat bottom surface 3a which spreads in the horizontal direction, and a peripheral wall 3b standing up from the outer peripheral edge of the bottom surface 3a. A portion surrounded by the bottom surface 3 a and the peripheral wall 3 b is an annular water channel C surrounding the upper outer periphery of the center well 2.

  An introduction pipe 8 is provided as a member for introducing the water to be treated so that the water to be treated flows into the annular water passage C in the circumferential direction. The end portion of the introduction pipe 8 extends along the peripheral wall 3b as shown in FIG. 2, and the water to be treated flows into the annular water channel C along the peripheral wall 3b and is swirled in the annular water channel C. , Flows into the center well 2.

  A plurality of pivot stop plates 5 are provided on the upper inner peripheral surface of the center well 2 as a pivot stop member for stopping the swirl of water flowing from the annular water channel C into the center well 2. Each turning stop plate 5 has a plate surface in the vertical direction, and protrudes from the inner peripheral surface of the center well 2 in the centripetal direction (direction toward the center of the center well 2). The width of the center stop plate 5 in the centripetal direction is preferably 5 to 20%, particularly 8 to 15%, of the diameter of the inner peripheral surface of the upper portion of the center well 2. The vertical length of the swing stop plate 5 is preferably 5 to 40%, particularly 10 to 30% of the diameter of the inner peripheral surface of the upper portion of the center well 2. When the diameter of the center well 2 is 100 to 200 cm, the number of installed turning stop plates 5 is preferably 12 to 36, particularly 18 to 30 or so. From the lower end of the swirling flow stop member to the lower end of the center well 2 in order to change the downward flow, at which the swirling has stopped, to a more even flow rate extrusion flow from the lower end of the swirling flow stop member to the lower end of the center well 2 It is preferable to set it as 150 cm or more. Moreover, in order to realize this, it is preferable to reduce the length of the turning stop member in the depth direction as much as possible, for example, 10 to 50 cm.

  A plate 4 commonly referred to as a flat baffle is provided facing the lower end of the center well 2 to make the flow direction of the raw water from the center well 2 a radial direction. In this embodiment, the plate 4 is in the form of a horizontal disk. The plate 4 is located below the lower end of the center well 2 by a predetermined distance. The plate 4 and the center well 2 are coaxially arranged.

  A later-described rake shaft 10 passes through the central portion of the plate 4, and the plate 4 is supported by the rake shaft 10. However, the plate 4 may be supported by the center well 2 via a support member (not shown).

  The radius of the plate 4 is not less than the radius of the center well 2 and not more than 1.5 times the radius, and preferably about 1 to 1.3 times the radius of the center well 2.

  The bottom of the tank body 1 has a downward slope toward the center, and a pit 6 for collecting and discharging the sedimented sludge is provided at the center of the bottom. The sludge in the pit 6 is discharged to the outside of the tank body 1 through the mud pipe 7. However, the bottom surface of the tank body 1 may be horizontal.

  A rake device is provided to rotate the rake plate 11 along the bottom surface of the tank body 1. The rake apparatus includes a rake shaft 10 vertically extending through an axial center portion of the center well 2, a support arm 12 radially extending from a lower portion of the rake shaft 10, and the arm 12 And a driving device (not shown) in which the upper end of the rake shaft 10 is connected.

  The rake plate 11 is disposed in a direction oblique to the longitudinal direction of each arm 12 so as to move the deposit on the bottom of the tank body to the center side of the bottom of the tank body when the rake rotates.

  An overflow weir 13 is provided along the upper part of the inner peripheral wall surface of the tank body 1 as an overflow part. The level at the upper end of the overflow weir 13 is the water level WL in the tank body 1.

  The water depth of the tank body 1, that is, the height from the bottom surface of the tank body to the water level WL is preferably 100 to 600 cm, and more preferably 200 to 450 cm.

  The height of the upper surface of the plate 4 from the bottom of the tank body (peripheral portion of the pit 6) is 20 to 150 cm, preferably 25 to 120 cm, particularly 30 to 80 cm.

  The downward flow velocity (LV) in the center well 2 is preferably 10 cm / sec or less, for example, about 1 to 6 cm / sec, particularly about 2 to 4 cm / sec.

  The vertical velocity of the raw water outlet between the lower end of the center well 2 and the upper surface of the plate 4 is such that the horizontal linear velocity of the raw water flowing out from this raw water outlet is about 1 to 10 cm / sec, especially about 2 to 6 cm / sec. It is preferable to set to.

  The rising flow rate (LV) in the tank body 1 is preferably 1 m / hr or more, for example, 1 to 15 m / hr, particularly about 2 to 8 m / hr.

  In the settling tank configured as described above, the water to be treated is supplied to the annular water channel C in the center well upper 3, swirls in the annular water channel C, flows into the center well 2, and swirls by the swirl stop plate 5. It is stopped, descends in the center well 2, and radially flows out from between the lower end of the center well 2 and the plate 4. Thereafter, the water ascends in the tank body 1, overflows the overflow weir 13, and is discharged from the clear water outlet 14.

  In this embodiment, the water to be treated descends from the lower end of the winding stop plate 5 in the center well 2 with no or almost no swirling, and after the uniform downward flow, the lower end of the center well 2 and From the raw water outlet with the plate 4 radially evenly into the sludge blanket. In addition, the difference in the rising flow velocity between the corner portion 1c of the tank body 1 and the side central portion 1f is reduced. As a result, sludge is efficiently separated and separated.

  The sludge that has settled on the bottom of the tank body 1 is scraped into the pits 6 by the lake and discharged from the sludge pipe 7.

  Other examples of the pivot stop member will be described with reference to FIGS.

  FIG. 4 shows a turning stop member 20 in which a plurality of flat plates 21 and 22 are provided in two orthogonal directions. The flat plates 21 and 22 may be installed at the upper part of the center well 2 by connecting both ends to the inner peripheral surface of the center well 2. Also, as shown in FIG. 4B, the flat plates 21 and 22 are combined in advance and combined to form a unit, and this unit is set on the top of the center well 2 by locking it on the top of the center well 2 with a hook member or the like. May be The unitized pivot stop can also be installed in the center well of the existing settling tank. The pivot stop members of FIGS. 5 to 8 which will be described next may be similarly unitized.

  The turning stop members 30 and 40 in FIGS. 5 and 6 are formed of a plurality of cylindrical bodies 31 or 41 disposed with the direction of the cylinder axis as the vertical vertical direction. In FIG. 5, the cylinder 31 is a triangular cylinder, and in FIG. 6, the cylinder 41 is a cylinder. A rectangular cylinder other than a triangle may be used.

  The turning stop member 50 of FIG. 7 is composed of a plurality of arc-shaped plates 51 having a shape obtained by cutting a cylinder in a direction parallel to the axial center line. The plate 51 is disposed vertically in the vertical direction.

  The turning stop member 60 shown in FIG. 8 is provided by arranging a plurality of cylinders 61 such that the axial centers of the columns are in the vertical direction. A prism or the like may be used instead of the cylinder.

  Although illustration is abbreviate | omitted, you may combine the cylinder of FIG. 5-8, a plate, or a cylinder.

  In the above embodiment, the plate 4 is horizontal, but at least the vicinity of the center may be an inclined surface less than 15 ° in the radial direction. However, at least the outer peripheral portion is preferably horizontal.

  In the above embodiment, the tank body 1 is a square, but may be a non-circular shape, and may be a pentagon or larger polygon or an oval.

  In the said embodiment, although the introductory pipe 8 is provided as an introductory member, you may provide a weir-like water channel as an introductory member.

  In the above embodiment, the center well 2 has an equal diameter from the upper end to the lower end, but the lower portion may have a large diameter. In this case, the lower end may be tapered with a larger diameter.

1 tank body 2 center well 2t upper end 3 center well upper 3a bottom 3b peripheral wall 4 plate 5 turn stop plate 6 pit 8 introduction pipe 10 rake shaft 13 overflow weir 20, 30, 40, 50, 60 turn stop member

Claims (9)

This is a settling tank in which the water to be treated supplied from the center well of the central part of the tank body to the lower part of the tank body ascends in the tank body and clears out from the overflow part of the tank body upper part ,
There is provided a center well upper member which forms an annular channel at the top of the center well.
In the settling tank, the water to be treated is introduced into the annular water channel by the introduction member in the circumferential direction along the peripheral wall, and flows into the center well,
The upper part of the said center well, a settling tank provided with a pivot stop member for stopping the turning of the water to be treated,
The settling tank characterized in that the distance from the lower end of the swing stop member to the lower end of the center well is 150 cm or more .   The settling tank according to claim 1, wherein the swing stopping member is formed of a plurality of plates extending in the vertical direction from the inner circumferential surface of the center well in the centripetal direction.   The sedimentation tank according to claim 2, wherein the width in the centripetal direction of the plate is 5 to 20% of the inner diameter of the upper portion of the center well. According to claim 1, wherein the pivot stop member is disposed in two orthogonal directions, Ri name than the plate where the plate surface and the vertical direction,
(A) The pivoting stop member is installed in the center well by connecting both ends of each plate to the inner peripheral surface of the center well, or
(B) The pivoting stop member is a unit in which the respective plates are combined and coupled, and the unit is installed in the center well by being locked to the center well. A precipitation tank characterized by According to claim 1, wherein the pivot stop member, Ri Na from a plurality of tubular body or column body that extends in a vertical direction,
A plurality of the cylinders or columns are combined and coupled into a unit, and the unit is installed in the center well by being locked to the upper portion of the center well. Settling tank. The settling tank according to claim 4, wherein the turning stop member is installed in the center well by the method (B), and the unit is detachably locked to the center well. . The settling tank according to claim 5 , wherein the unit is detachably locked to the center well. The precipitation tank according to any one of claims 1 to 7 , wherein a plate for changing the flow direction of the water is provided at the lower end of the center well. The sedimentation tank according to any one of claims 1 to 8 , wherein the tank body has a rectangular shape in a plan view.

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