JP7396734B2 - sand pond - Google Patents

Description

The present invention relates to a settling pond in which sand contained in received water settles to the bottom of the pond.

Sewage treatment facilities receive wastewater such as sewage and rainwater, and after settling the sand contained in the wastewater into the bottom of the pond or in the grooves provided at the bottom of the pond, the sand is deposited on the bottom or in the grooves. Some have a settling basin that collects sand in a sand collection pit and removes it from the wastewater. As this settling basin, after draining the wastewater in the settling basin and exposing the sand accumulated on the bottom to the atmosphere, the sand is directed toward the groove by fluid discharged from multiple outlets installed near the side walls of the settling basin. There are some known sand collection systems that are equipped with a means to collect sand. This groove is composed of a long gutter-like member made from a stainless steel plate with a U-shaped or arc-shaped cross section. It extends in a perpendicular direction that is orthogonal to the direction. The sand swept into the trench is transported to the sand collection pit by the flow of fluid supplied into the trench, and is discharged to the outside of the sand settling basin by a sand pump disposed within the sand collection pit.

Incidentally, the settling basin is sometimes equipped with a dust remover for removing contaminants (sludge) mixed into the sewage that has flowed into the settling basin. The dust remover is formed to have approximately the same width as the width of the sand settling basin so that there is no gap between the dust remover and the side wall of the sand settling basin. However, some settling ponds are more than 4 meters wide. If you use a dust remover with the same width as the pond width in such a wide settling basin, the load on the dust remover will increase when the amount and flow velocity of wastewater flowing into the settling basin increases due to heavy rain, etc. If you do too much, there is a risk that the dust remover will be damaged. In order to prevent this damage, a sand settling basin has been proposed in which a protruding wall is formed at the center of the settling basin in the width direction of the basin, and two dust removers are arranged side by side in the basin width direction with the protruding wall in between. As a result, even if the amount and flow rate of wastewater flowing into the settling basin increases, the load applied to each dust remover can be reduced, making the dust remover less likely to be damaged. Furthermore, even if a dust remover is not present, a protruding wall may be provided for the purpose of supporting the ceiling.

When a protruding wall is formed, the arrangement of the grooves in the settling basin becomes a problem. That is, since there is a region where a protruding wall exists in the center of the settling basin in the width direction of the basin, it is not possible to arrange a groove in the center of the basin in that area. On the other hand, a Y-shaped groove is formed when viewed from above the settling basin, consisting of a bifurcated part and a single straight part, and the bifurcated part is the width of the protruding wall. A sand settling pond arranged on both sides of the direction has been proposed (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 2011-245393

Since the Y-shaped groove has a complicated shape, it is difficult to process it from a single plate. Therefore, there is a problem in that it is necessary to create at least three parts, each bifurcated part and a straight part, and to join them by welding or the like to form a Y-shape, which is a complicated process. Another problem is that in order to align the heights of the parts and join them together, a jig or the like is required to maintain the height of each part. Furthermore, when transporting a trench created in a factory or the like to a settling basin, the Y-shaped trench is bulky, so there is a problem in that the transporting devices that can load it are limited.

To solve these problems, instead of using a Y-shaped groove, we adopted two straight grooves that extend from the edge of the sand settling basin to the sand collection pit, and lined up the two grooves in the width direction of the basin with a protruding wall in between. It is possible to arrange it. By employing two linear grooves, the complicated work of creating a Y-shaped groove becomes unnecessary. Furthermore, when conveying the grooves to the sand settling basin, it is possible to carry two linear grooves in an overlapping manner, so it is possible to expand the selection of transport devices that can be loaded.

However, when two straight grooves are used, even if fluid is discharged from the discharge port provided near the side wall of the settling basin, the fluid is blocked by the grooves, so that some of the sand that has settled on the bottom surface is blocked by the grooves. A new problem arises in that the sand that settles between the grooves cannot be washed away with fluid and remains behind.

In view of the above circumstances, an object of the present invention is to provide a sand settling basin that can collect settled sand in the groove without leaving it on the bottom surface between two grooves.

The settling basin of the present invention which solves the above object allows the received water to flow down in a direction orthogonal to the width direction of the pond between one side wall and the other side wall constituting the end face in the width direction of the pond. In the settling pond that settles the sand contained in it,
a first groove and a second groove provided in the pond bottom at intervals in the pond width direction;
a protruding wall formed between the first groove and the second groove and protruding upward from the pond bottom;
A ridgeline portion extending along the orthogonal direction between the first groove and the second groove in the pond bottom portion, a first connection surface connecting the ridgeline portion and the first groove; A second connection surface connecting the ridgeline portion and the second groove is connected to the protruding wall, and
The first connection surface is an inclined surface that slopes downward from the ridgeline toward the first groove,
The second connection surface is an inclined surface that slopes downward from the ridgeline toward the second groove,
The first groove is provided on the one side wall side,
The second groove is provided on the other side wall,
a first bottom surface formed between the one side wall and the first groove and inclined downward toward the first groove;
a second bottom surface formed between the other side wall and the second groove and inclined downward toward the second groove;
Each of the first connection surface and the second connection surface is characterized in that the angle of inclination is steeper than the angle of inclination of the first bottom surface and the second bottom surface.

In this sand settling basin, a first discharge port that discharges a fluid for flowing sand settled on the first bottom surface from the one side wall side toward the first groove;
A second discharge port may be provided for discharging a fluid for causing the sand settled on the second bottom surface to flow from the other side wall toward the second groove.

According to the present invention, it is possible to provide a sand settling basin that can collect settled sand in the groove without leaving it on the bottom surface between two grooves.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional view of a sewage treatment facility including a settling basin corresponding to one embodiment of the present invention. FIG. 1 is a plan view of a sand settling basin, seen from above, according to an embodiment of the present invention. FIG. 3 is a cross-sectional view taken along line XX of the sand settling basin shown in FIG. 2. FIG. 3 is a sectional view taken along line AA of the sand settling basin shown in FIG. 2. FIG. 5 is an enlarged view showing part B in FIG. 4; (a) is a sectional view for explaining the state in which one pipe provided with a lap joint is connected to the other pipe, and (b) is a sectional view showing one pipe provided with a lap joint by loosening the bolt. FIG. 2 is a cross-sectional view for explaining a state in which one tube is rotatable about the other tube in its axial direction. (a) is a cross-sectional view taken along the line CC in FIG. 5, and (b) is a cross-sectional view similar to (a) showing the bottom near the upstream end of the sand settling basin and the bottom near the sand collection pit. (c) is a sectional view similar to (a) for explaining the change in the discharge direction by the sand collecting nozzle. It is a water supply system diagram in a sewage treatment facility. It is an explanatory view showing a water level of a sand settling pond and a water level sensor. 5 is a cross-sectional view of the sand settling basin similar to FIG. 4, showing a case where the sand collecting means is arranged in the upper part of the sand settling basin and a case where the sand collecting means is arranged near the bottom of the sand settling basin. FIG. 4 is a cross-sectional view similar to FIG. 3 showing a modification of the connection surface. (a) is a diagram showing a first modification of the supply pipe and sand collection nozzle shown in FIG. 7, and (b) is a diagram showing a second modification of the supply pipe and sand collection nozzle shown in FIG. 7. be.

Embodiments of the present invention will be described below with reference to the drawings. A settling basin, which is an embodiment of the present invention, is placed in a sewage treatment facility, and after settling sand contained in wastewater such as sewage and rainwater, the settled sand is moved to a sand collection pit and removed from the wastewater. It is something.

FIG. 1 is a schematic sectional view of a sewage treatment facility including a settling basin according to an embodiment of the present invention.

As shown in FIG. 1, the sewage treatment facility 1 includes a settling basin 2, a pump well 3, and a dam device 4. Wastewater such as sewage and rainwater flows into the sewage treatment facility 1. The sewage treatment facility 1 receives sewage from the left side in FIG. The received sewage flows slowly toward the pump well 3 on the right side of the figure in the settling basin 2, while settling the sand contained in the sewage (see the straight arrow shown in Fig. 1). Hereinafter, the upstream side of the flow of received wastewater will be simply referred to as the upstream side, and the downstream side of the flow of the received wastewater will be simply referred to as the downstream side.

A dam device 4 is arranged in the sewage treatment facility 1 upstream of the settling basin 2. This dam device 4 has an opening wall 41, an inflow gate 42, and a gate drive device 43. The downstream wall surface of the opening wall 41 defines the upstream end of the sand settling basin 2 . An inlet 411 is opened at the lower end of the opening wall 41 . The inflow gate 42 is provided so as to be movable up and down along the wall surface on the upstream side of the opening wall 41 . When the inlet gate 42 is in the lower position shown by the solid line in FIG. 1, it closes the inlet 411 and prevents wastewater located upstream of the dam device 4 from flowing into the settling basin 2. Furthermore, when the inflow gate 42 is pulled up to the upper position shown by the two-dot chain line in FIG. 1, sewage is allowed to flow into the settling basin 2. The gate drive device 43 has a drive mechanism (not shown) therein, and moves the inflow gate 42 up and down in response to a command from a control device that controls the dam device 4 . By this vertical movement, the inflow gate 42 is selectively placed in either the upper position or the lower position.

The sand settling basin 2 is provided with a dust remover 5 disposed on the upstream side thereof, a sand collecting pit 6 disposed near the midstream, and a sand pump 61 for transporting the sand in the sand collecting pit 6 to the outside of the pond. It is being A sand pump 61 is connected to a sand pump 64 . The sand sucked by the sand pump 61 is sent to a sand separator (not shown) provided outside the sand settling basin 2 through the sand pump 64. The dust remover 5 is for removing contaminants (sludge) mixed into the wastewater that has flowed into the settling basin 2. The configuration of the sand settling basin 2 will be detailed later.

A pump well 3 is formed downstream of the settling basin 2 in the sewage treatment facility 1 . The pump well 3 stores wastewater from which sand has been removed by the settling basin 2. The bottom of the pump well 3 is the deepest part in the wastewater treatment facility 1. In the pump well 3, a lift pump 31 and a water supply pump 33 are arranged. The pump 31 moves the wastewater stored in the pump well 3 to the outside of the wastewater treatment facility 1 . A lift pipe 32 is connected to the lift pump 31 . The sewage sucked by the pump 31 is sent through the pump pipe 32 to a sedimentation tank (not shown) or the like where the next stage of sewage treatment is performed. The water supply pump 33 is located closer to the bottom of the pump well than the water pump 31 described above. A water supply pipe 34 is connected to the water supply pump 33 . Dirty water sucked by the water supply pump 33 is sent to each nozzle, etc., which will be described later, through this water supply pipe 34. The dirty water sucked by the water supply pump 33 will be referred to as fluid in the following description.

FIG. 2 is a top plan view of a sand settling basin according to an embodiment of the present invention. In FIG. 2, the dust remover is shown by a rectangular double-dashed line. In addition, the flow direction of wastewater is indicated by a straight arrow.

As shown in FIG. 2, the sand settling basin 2 includes a dust remover 5, a sand collecting pit 6, a bottom surface 7, a main trough 8, and a sand collecting means 9 between the left side wall Wa and the right side wall Wb. In addition, the pond is approximately rectangular in plan view. Hereinafter, the left side wall Wa and the right side wall Wb may be collectively referred to as a side wall W. A protruding wall 10 for supporting the dust remover 5 is provided at the center in the width direction of the sand settling basin 2 on the upstream side. The sand collection pit 6, the bottom surface 7, and the main trough 8 are each provided at the bottom of the sand settling basin 2. The main trough 8 extends longitudinally from near the upstream end of the sand settling basin 2 and includes a first upstream main trough 815 and a second upstream main trough 816 connected to the sand collection pit 6 , and a second upstream main trough 816 . The main trough 82 extends longitudinally from the vicinity of the downstream end and is connected to the sand collecting pit 6. The first upstream main trough 815 corresponds to an example of a first groove, and the second upstream main trough 816 corresponds to an example of a second groove. This sand settling tank 2 collects the sand settled on the bottom surface 7 by discharging low pressure water of less than 3 kg/cm2 onto the bottom surface 7 after draining the wastewater in the sand settling tank 2. It is a settling pond. Hereinafter, the long side direction of the sand settling basin 2 will be referred to as the longitudinal direction, and the short side direction will be referred to as the pond width direction. This longitudinal direction is also an orthogonal direction orthogonal to the pond width direction.

A building, piping, etc. (not shown) may be arranged above the settling basin 2 (on the front side of the page in FIG. 2). A column 11 may be formed adjacent to the settling basin 2 for the purpose of supporting the building or the like. In the sand settling basin 2 shown in FIG. 2, a column 11 is formed near the left side wall Wa. A portion of the left side wall Wa that becomes the base of the pillar 11 is formed with a convex wall portion Wa1 that protrudes toward the center in the pond width direction. Conversely, it can be said that in a portion of the left side wall Wa where the column 11 is not present on the left side wall Wa, a recessed wall portion Wa2 recessed toward the outside in the pond width direction is formed. In addition, an inclined wall portion Wa3 inclined with respect to the longitudinal direction and the pond width direction is formed at a portion connecting the convex wall portion Wa1 and the recessed wall portion Wa2. Note that since there is no pillar 11 near the right side wall Wb, the right side wall Wb is formed into a substantially straight line in plan view.

The sand collection pit 6 is arranged at a position slightly downstream of the center of the sand settling basin 2 in the longitudinal direction. This sand collection pit 6 is constituted by a recess formed in the center of the sand settling basin 2 in the width direction of the basin. Inside the sand collecting pit 6, a sand pump 61 and a stirring nozzle 62 are arranged. This sand collecting pit 6 is the deepest part of the settling basin 2. This sand collection pit 6 has a rectangular shape in plan view. Between the side wall W and the sand collection pit 6, there is a sand collection pit slope surface 6b that is inclined so as to gradually become deeper toward the sand collection pit 6 side located at the central part in the pond width direction.

A total of four stirring nozzles 62 are arranged near each corner of the sand collecting pit 6. This stirring nozzle 62 is for stirring the sand collected in the sand collecting pit 6. By discharging fluid from the discharge port 62a of the stirring nozzle 62 while the sand pump 61 is being driven, the suction efficiency of the sand collected in the sand collection pit 6 by the sand pump 61 can be increased. Two pit sand collecting nozzles 63 are arranged at each end of the sand collecting pit slope 6b in the pond width direction. By discharging fluid from the outlet 63a of the pit sand collection nozzle 63 with the water level of the sand settling basin 2 lower than a predetermined value, the sand accumulated on the sand collection pit slope 6b is removed from the sand collection pit 6. can be collected in.

The bottom surface 7 includes a planar bottom surface 71, a plurality of small troughs 72, and a connecting surface 73. The bottom plane 71 includes a first bottom surface 711 formed between the left side wall Wa and the first upstream main trough 815, and a second bottom surface 712 formed between the right side wall Wb and the upstream second main trough 816. , a third bottom surface 713 formed between the left side wall Wa and the downstream main trough 82, and a fourth bottom surface 714 formed between the right side wall Wb and the downstream main trough 82. The bottom plane 71 and the small trough 72 are connected to the main trough 8 at the center of the sand settling basin 2 in the width direction. The bottom plane 71 is inclined downward by about 5 degrees from the side wall W at the outer end in the pond width direction toward the main trough 8 so that the end on the side of the main trough 8 is deepest. Further, the bottom plane 71 is inclined downward by about 1 degree in the longitudinal direction so that the end on the side of the sand collecting pit 6 is the deepest. The small trough 72 is a gutter-shaped thing with a U-shaped cross section, and extends in the pond width direction from the vicinity of the side wall W. A plurality of small troughs 72 are arranged at regular intervals in the longitudinal direction. In this embodiment, a total of 56 small troughs 72, 28 small troughs 72, are arranged on one side and the other side in the pond width direction with the main trough 8 in between. Similar to the bottom plane 71, this small trough 72 is also inclined downward by about 5 degrees from the side wall W side toward the main trough 8 side so that the part connected to the main trough 8 is located closest to the pond bottom. There is.

The first upstream main trough 815, the second upstream main trough 816, and the downstream main trough 82 are grooves formed by a trough forming body that is a stainless steel plate with a U-shaped cross section. The first upstream main trough 815, the second upstream main trough 816, and the downstream main trough 82 are inclined downward by about 1 degree toward the sand collection pit 6, similar to the bottom plane 71, and are The part connected to pit 6 is the deepest.

As shown in FIG. 2, the upstream first main trough 815 is provided on the left wall Wa side with respect to the center in the pond width direction, and extends in the longitudinal direction. Further, the upstream second main trough 816 is provided on the right side wall Wb side with respect to the center in the pond width direction, and extends in the longitudinal direction. The downstream ends of the first upstream main trough 815 and the second upstream main trough 816 are connected to the sand collection pit 6. An upstream trough first nozzle 831 is provided at the upstream end of the upstream first main trough 815 . Further, an upstream trough second nozzle 832 is provided at the upstream end of the upstream second main trough 816. By discharging fluid from the discharge port 831a of the upstream trough first nozzle 831 while the water level of the sand settling basin 2 is lower than a predetermined value, the sand accumulated in the upstream first main trough 815 is transferred to the sand collection pit 6. It can be moved. In addition, by discharging fluid from the discharge port 832a of the upstream trough second nozzle 832 while the water level of the sand settling basin 2 is lower than a predetermined value, the sand accumulated in the upstream second main trough 816 can be removed from the sand collection pit. It can be moved to 6.

The downstream main trough 82 extends linearly in the longitudinal direction at the center of the sand settling basin 2 in the width direction. The upstream end of the downstream main trough 82 is connected to the sand collection pit 6. A downstream trough nozzle 84 is provided at the downstream end of the downstream main trough 82 . To move the sand accumulated in the downstream main trough 82 to the sand collection pit 6 by discharging fluid from the discharge port 84a of the downstream trough nozzle 84 while the water level in the sand settling basin 2 is lower than a predetermined value. I can do it.

A protruding wall 10 for supporting the dust remover 5 is formed between the first upstream main trough 815 and the second upstream main trough 816 in the upstream portion of the sand settling basin 2 . This protruding wall 10 is a concrete wall that rises to near the upper end of the sand settling basin 2. The connecting surface 73 is located between the first upstream main trough 815 and the second upstream main trough 816 and at the bottom of the pond on the downstream side of the projecting wall 10 . That is, the connection surface 73 is formed between the first upstream main trough 815 and the second upstream main trough 816, excluding the area where the protruding wall 10 is provided. The connection surface 73 includes a ridgeline portion 731 extending along the longitudinal direction, a first connection surface 732 that connects the ridgeline portion 731 and the upstream first main trough 815, and a first connection surface 732 that connects the ridgeline portion 731 and the upstream second main trough 815. and a second connection surface 733 that connects to the trough 816. Note that the extending direction of the ridgeline portion 731 does not have to be completely the same as the longitudinal direction, and may be, for example, a direction slightly inclined in the pond width direction and the vertical direction with respect to the longitudinal direction. Moreover, the ridgeline portion 731 may meander somewhat in the pond width direction and the vertical direction. That is, "extending along the longitudinal direction" is a concept that includes some inclination and meandering.

FIG. 3 is a cross-sectional view taken along line XX of the sand settling basin shown in FIG.

As shown in FIG. 3, the first connection surface 732 is an inclined surface that slopes downward toward the upstream first main trough 815. Further, the second connecting surface 733 is an inclined surface that slopes downward toward the upstream second main trough 816. The first connection surface 732 and the second connection surface 733 are made of concrete surfaces. The inclination angle of the first connection surface 732 and the second connection surface 733 is about 45 degrees with respect to the horizontal plane. Since the connecting surface is inclined, sand that settles on the connecting surface 73 can be collected in the upstream first main trough 815 or the upstream second main trough 816 without leaving it on the connecting surface 73. . If the inclination angle of the first connection surface 732 and the second connection surface 733 is 15 degrees or more, most of the sand that settles on the connection surface 73 in the waste water in the settling basin 2 will be transferred to the connection surface 73 due to its own weight. slip down. Further, it is preferable that the inclination angle of the first connecting surface 732 and the second connecting surface 733 is 30 degrees or more, since the sand that settles on the connecting surface 73 will more easily slide down the connecting surface 73. However, if the inclination angle is made too large, the thickness of the concrete constituting the connection surface 73 in the pond width direction becomes too thin near the ridgeline portion 731, and the ridgeline portion 731 portion is likely to be damaged. Therefore, the angle of the ridgeline portion 731 formed by the first connection surface 732 and the second connection surface 733 is set so that the angle of the ridgeline portion 731 formed by the first connection surface 732 and the second connection surface 733 is 30 degrees or more. It is preferable to do so. Note that one or both of the first connection surface 732 and the second connection surface 733 does not need to be configured as a single plane, and may be configured as a plurality of surfaces with different inclination angles, for example. In this case, the inclination angles of all the surfaces may be 15 degrees or more. Moreover, one of the first connection surface 732 and the second connection surface 733 may be a vertical surface, and the other may be a slope surface. However, by making each of the first connecting surface 732 and the second connecting surface 733 an inclined surface as in this embodiment, the sand is distributed to the upstream first main trough 815 and the upstream second main trough 816 and is slid off. Therefore, it is preferable to make each surface sloped. Further, as in the present embodiment, by providing the ridgeline portion 731 in the center portion between the upstream first main trough 815 and the upstream second main trough 816, the upstream first main trough 815 and the upstream second main trough 816 The amount of sand sliding into the main trough 816 can be made uniform. By doing this, it is possible to prevent a large amount of sand from accumulating on one of the upstream first main trough 815 and the upstream second main trough 816, so that the upstream first main trough 815 and the upstream second main trough 815 are It is possible to prevent sand from being unable to be transported to the sand collection pit 6 due to sand transport resistance within the second main trough 816.

As shown in FIG. 2, two dust removers 5 are provided in the upstream portion of the sand settling basin 2 in parallel in the basin width direction with a protruding wall 10 in between. In other words, one dust remover 5 is disposed between the left side wall Wa and the protruding wall 10, and one between the right side wall Wb and the protruding wall 10. These two dust removers 5, 5 have the same configuration. The dust remover 5 is for removing contaminants (sludge) mixed into the wastewater that has flowed into the settling basin 2. One dust remover 5 shown on the upper side of FIG. 2 is supported by the left side wall Wa and the protruding wall 10, and the other dust remover 5 shown on the lower side of FIG. 2 is supported by the right side wall Wb. It is supported by a protruding wall 10. By arranging the two dust removers 5, 5 side by side in the pond width direction, the width of each dust remover 5 in the pond width direction can be shortened. By shortening the width of the dust remover 5 in the pond width direction, the strength of the dust remover 5 is increased, and even if the amount and flow rate of sewage flowing into the settling tank 2 increases due to heavy rain, etc., the dust remover 5 will not be damaged. It can prevent you from putting it away.

FIG. 4 is a sectional view taken along line AA of the sand settling basin shown in FIG. In FIG. 4, the columns and the sand pump are not shown, and the shape of the protruding wall is shown by a chain double-dashed line. In addition, the flow direction of wastewater is indicated by a straight arrow. Note that the water surface WL of the settling basin changes depending on the amount of rain and sewage flowing in, but under normal conditions when the amount of rain and sewage is expected, the water surface WL of the settling basin 2 changes in the height direction of the settling basin 2, as shown in Figure 4. It is located at a medium height.

As shown in FIG. 4, the dust remover 5 includes an endless chain 51, a plurality of rakes 52 attached to the endless chain 51 at intervals, and a filter screen 53. The endless chain 51 is provided in an oblique manner on both sides of the sand settling basin 2 in the width direction, and is wound around the ground side sprocket 511 and the pond bottom side sprocket 512. The upper part of the endless chain 51 and the above ground sprocket 511 are arranged in the above ground part of the sand settling basin 2. When the water surface WL is in a normal state, when the ground side sprocket 511 is driven by a motor (not shown) in the rotational direction indicated by an arcuate arrow R, the endless chain 51 circulates and the rake 52 moves in and out of the water. FIG. 4 shows the water surface WL in a normal state. The protruding wall 10 protrudes above the water surface WL. However, especially when the protruding wall 10 is formed for a purpose other than supporting the dust remover 5, the protruding wall 10 may be lower than the water surface WL. The filter screen 53 is arranged downstream of the endless chain 51. The filtration screen 53 has vertically extending bars arranged at predetermined intervals (for example, 25 mm to 75 mm) in the pond width direction, and blocks the passage of contaminants larger than the predetermined interval. The contaminants blocked by the filter screen 53 are scraped up by the rake 52, and the scraped up contaminants are placed on a conveying means such as a belt conveyor (not shown) on the ground side. Note that the lower ends of the pond bottom side sprocket 512 and the filtration screen 53 are arranged upstream of the bottom surface 7 and the main trough 8. On the other hand, the upper ends of the ground side sprocket 511 and the filter screen 53 are located above the bottom surface 7 and the upstream portion of the main trough 8. That is, the upper portions of the endless chain 51 and the filter screen 53 overlap the bottom surface 7 and the main trough 8 in the longitudinal direction.

The sand collecting means 9 includes a first nozzle header 9a, a second nozzle header 9b, and a third nozzle header 9c arranged on the left side wall Wa of the sand settling basin 2, and a fourth nozzle header 9d arranged on the right side wall Wb. , a fifth nozzle header 9e, and a sixth nozzle header 9f (see FIG. 2). In FIG. 4, the sand collection means 9 on the left side wall Wa is shown. Since the sand collecting means 9 on the right side wall Wb side has a similar configuration, the description of the sand collecting means 9 on the right side wall Wb side will be omitted. Each of the first nozzle header 9a, the second nozzle header 9b, and the third nozzle header 9c includes ten sand collection nozzles 91, a supply pipe 92, and a main pipe 93. The supply pipe 92 is arranged to face the left side wall Wa and extends in the longitudinal direction. The main pipe 93 includes a single pipe 931 extending above the sand settling basin 2 and a branch pipe 932 connected to the end of the single pipe 931 on the pond bottom side. The single pipe 931 and the branch pipe 932 are fixed to the left side wall Wa using fixing fittings (not shown).

FIG. 5 is an enlarged view of section B in FIG. 4. FIG. In FIG. 5, the flow direction of wastewater is shown by a straight arrow. Also shown in FIG. 5 are side walls. Further, although FIG. 5 shows one of the six nozzle headers, the other five nozzle headers also have the same configuration as the nozzle header shown in FIG. 5.

As shown in FIG. 5, the branch pipe 932 is connected to the single pipe 931 by a flange joint 933. The branch pipe 932 branches into two parts below the part connected to the single pipe 931, and the branched parts each extend in the longitudinal direction of the sand settling basin 2. Supply pipes 92 each having a lap joint 934 fixed thereto are connected to the distal end portions of the branch portions. In this embodiment, with respect to one main pipe 93, an upstream supply pipe 921 disposed upstream of the branch pipe 932, a downstream supply pipe 923 disposed downstream of the branch pipe 932, Three supply pipes 92 are provided, an intermediate supply pipe 922 disposed between an upstream supply pipe 921 and a downstream supply pipe 923. The other end of the upstream supply pipe 921 and the downstream supply pipe 923, which is opposite to the one end connected to the branch pipe 932, is closed by a lid 97. Both ends of the intermediate supply pipe 922 are connected to a branch pipe 932.

Three sand collecting nozzles 91 are fixed to each of the upstream supply pipe 921 and the downstream supply pipe 923 at equal intervals. Further, four sand collection nozzles 91 are fixed to the intermediate supply pipe 922 at equal intervals. A total of ten sand collection nozzles 91 are arranged at equal intervals. Furthermore, the interval between the most downstream sand collecting nozzle 91 of the first nozzle header 9a (see FIG. 2) and the most upstream sand collecting nozzle 91 of the second nozzle header 9b is also the same as that of the ten sand collecting nozzles described above. The interval is the same as the interval. That is, all the sand collection nozzles 91 are arranged at equal intervals in the longitudinal direction of the sand settling basin 2. Note that the number of sand collection nozzles 91 arranged in each supply pipe 92 may be determined as appropriate depending on factors such as the length of the supply pipe 92. A discharge port 911 is formed at the tip of each sand collection nozzle 91 . Among the respective discharge ports 911, the discharge ports 911 provided in the first nozzle header 9a (see FIG. 2) and the second nozzle header 9b correspond to an example of the first discharge ports, and the discharge ports 911 provided in the fourth nozzle header 9d and the fifth The discharge port 911 provided in the nozzle header 9e (see FIG. 2) corresponds to an example of a second discharge port. By lowering the water level of the sand settling basin 2 below a predetermined value and exposing the sand accumulated on the bottom surface 7 and the discharge port 911 to the atmosphere, the fluid is discharged from the discharge port 911 into the atmosphere. Sand deposited on the bottom surface 7 shown in FIGS. 2 and 4 can be collected in the main trough 8.

The distance from the supply pipe 92 to the left side wall Wa is different between the part of the supply pipe 92 that faces the protruding wall Wa1 and the part that faces the recessed wall Wa2. That is, the supply pipe 92 includes a first region 92a extending from the left wall Wa in the pond width direction at a first interval, and a second region 92a extending from the left wall Wa in the pond width direction at a second interval. There is a region 92b. In addition, since the sand settling basin 2 of this embodiment has an inclined wall portion Wa3 formed at a portion connecting the convex wall portion Wa1 and the concave wall portion Wa2, the supply pipe 92 has the first region and the concave wall portion Wa2. There is a third region 92c that is a region connecting the second regions. Each sand collection nozzle 91 and its discharge port 911 are arranged facing the left side wall Wa, and are fixed to the supply pipe 92 in line with the longitudinal direction. In the second nozzle header 9b shown in FIG. 5, the upstream supply pipe 921 is arranged to face the convex wall portion Wa1. That is, the area where the upstream supply pipe 921 is located corresponds to the first area 92a. On the other hand, a region of the intermediate supply pipe 922 where the discharge port 911 is located closest to the upstream supply pipe 921 is arranged to face the inclined wall portion Wa3. That is, this area corresponds to the third area 92c. Also, in the intermediate supply pipe 922, there is a region where three discharge ports 911 are arranged from the downstream supply pipe 923 side, and in the downstream supply pipe 923, two discharge ports 911 are arranged from the intermediate supply pipe 922 side. The arranged region is arranged facing the recessed wall portion Wa2. That is, those areas correspond to the second area 92b. Further, in the downstream supply pipe 923, a region where the discharge port 911 located on the most downstream side is arranged is arranged to face the inclined wall portion Wa3. That is, this area corresponds to the third area 92c. Direction changing means using lap joints 934 is provided between each of these regions.

FIG. 6(a) is a cross-sectional view for explaining the state in which one pipe provided with a lap joint is connected to the other pipe, and FIG. 6(b) is a sectional view for explaining the state in which one pipe provided with a lap joint is connected to the other pipe, and FIG. 6(b) shows that the lap joint can be opened by loosening the bolt. FIG. 3 is a cross-sectional view for explaining a state in which one of the provided tubes is rotatable about the other tube in its axial direction. In FIG. 6, a supply pipe is shown as one pipe, and a branch pipe is shown as the other pipe, but the configuration is similar when the supply pipes are connected by providing a lap joint.

As shown in FIGS. 6(a) and 6(b), a lap joint 934 is welded to the end of the supply pipe 92. This lap joint 934 is composed of a small diameter part 934a welded to the supply pipe 92 and a large diameter part 934b arranged on the branch pipe 932 side. The outer diameter of the small diameter portion 934a is formed to be the same as the outer diameter of the supply pipe 92. A free flange 935 is arranged around the outer periphery of the lap joint 934. The free flange 935 has a ring shape with an inner diameter slightly larger than the outer diameter of the lap joint 934. In the free flange 935, eight free flange through holes 935a into which the bolts 95 are inserted are formed evenly in the circumferential direction. The free flange 935 is coupled to the lap joint 934 so as to be rotatable and movable in the axial direction relative to the lap joint 934. A fixed flange 9322 is welded to the outer diameter portion of the tip of the branch pipe 932. This fixed flange 9322 is formed with eight fixed flange through holes 9322a into which bolts 95 are inserted, similarly to the free flange 935. A ring-shaped packing 94 is arranged between the lap joint 934 and the fixed flange 9322. This packing 94 is for preventing the fluid passing through the supply pipe 92 and the branch pipe 932 from leaking when the supply pipe 92 and the branch pipe 932 are connected.

The bolts 95 are inserted into fixed flange through holes 9322a of the fixed flange 9322 and free flange through holes 935a of the free flange 935. When the bolts 95 and nuts 96 are tightened, the lap joint 934 and the packing 94 are sandwiched between the fixed flange 9322 and the free flange 935, as shown in the supply pipe 92 shown in FIG. A supply tube 92 is fixed to 932. On the other hand, when the bolt 95 is loosened, the supply pipe 92 becomes rotatable about its axial direction with respect to the branch pipe 932, as shown in the supply pipe 92 shown in FIG. 6(b). That is, in this embodiment, since the main pipe 93 (see FIG. 4) and the supply pipe 92 are connected using the lap joint 934 and the free flange 935, the supply pipe 92 is It is configured to be able to rotate steplessly with respect to the main pipe 93. Note that even if another loose flange such as a loose flange is used in place of the lap joint 934, the supply pipe 92 can be connected to the main pipe 93 in a continuously rotatable manner.

Further, as shown in FIG. 5, between the discharge ports 911 arranged in the first region 92a and the discharge ports 911 arranged in the third region 92c, and between the discharge ports 911 arranged in the second region 92b and the third A lap joint 934 is arranged between each of the discharge ports 911 arranged in the region 92c. Therefore, the discharge ports 911 disposed in the first region 92a, the second region 92b, and the third region 92c are configured to be able to rotate steplessly about the axial direction of the supply pipe 92 independently of each other. With this configuration, the direction in which fluid is discharged from the discharge port 911 in each area can be set depending on the distance from the supply pipe 92 to the left side wall Wa. The lap joint 934 arranged between the discharge port 911 arranged in the first region 92a and the discharge port 911 arranged in the third region 92c corresponds to an example of a first direction changing means. Moreover, the lap joint 934 arranged between the discharge port 911 arranged in the second region 92b and the discharge port 911 arranged in the third region 92c corresponds to an example of the second direction changing means. Furthermore, in the first region 92a of the supply pipe 92 shown in FIG. The discharge direction can be easily adjusted. In the second region 92b of the supply pipe 92 shown in FIG. Since the outlets 911 can be changed all at once, the discharge direction in the second region 92b can be easily adjusted. That is, the lap joint 934 in the case where the discharge directions of the plurality of discharge ports 911 can be changed at once corresponds to an example of a collective direction changing means. Note that if the third region 92c is short in the longitudinal direction and the discharge port 911 does not exist in the third region 92c, or if the third region 92c does not exist, there is no overlap between the first region 92a and the second region 92b. A joint 934 may be placed.

FIG. 7(a) is a cross-sectional view taken along line CC in FIG. The side walls and bottom plane are also shown in FIG. 7(a).

As described above, the left side wall Wa has a convex wall portion Wa1 and a recessed wall portion Wa2. In FIG. 7A, the convex wall portion Wa1 is shown by a solid line, and the recessed wall portion Wa2 is shown by a two-dot chain line. In the discharge port 911 shown by a solid line in FIG. 7A, the fluid is discharged in a direction toward the center in the pond width direction rather than a direction directly downward from the center of the supply pipe 92 (vertical direction). In this discharge port 911, the angle θ at which the fluid is discharged with respect to the bottom plane 71 is approximately 50 degrees. By setting the angle θ to about 50 degrees, the fluid that has reached the bottom plane 71 can be divided into a direction toward the main trough 8 and a direction toward the convex wall portion Wa1. This angle θ may be any angle that allows the discharged fluid to separate into a direction toward the main trough 8 and a direction toward the convex wall portion Wa1, and specifically, is between 30 degrees and 60 degrees with respect to the bottom plane 71. Good to have. By setting this angle, when the supply pipe 92 and the left side wall Wa are close like the convex wall part Wa1, that is, in the first region 92a (see FIG. 6), the bottom between the supply pipe 92 and the left side wall Wa is The divided fluid also reaches the sand deposited on the plane 71 and can wash away the sand. In addition, since the discharge direction of the fluid is directed toward the main trough 8 at the center in the pond width direction rather than the vertical direction of the supply pipe 92, the fluid flowing toward the main trough 8 has a greater momentum than the fluid flowing toward the left wall Wa. becomes stronger. Due to the force of this fluid, the sand accumulated on the bottom plane 71 between the supply pipe 92 and the main trough 8 can be efficiently flowed toward the main trough 8.

On the other hand, in the concave wall portion Wa2 indicated by the two-dot chain line in FIG. 7(a), the supply pipe 92 and the left side wall Wa are separated from each other. Therefore, in the discharge direction of the discharge port 911 shown by the solid line, even if the discharged fluid is divided, it does not reach the vicinity of the recessed wall portion Wa2, or even if it does, only a very small amount of fluid reaches there. If the amount of fluid reaching the vicinity of the recessed wall Wa2 is small, the sand near the recessed wall Wa2 among the sand accumulated between the supply pipe 92 and the recessed wall Wa2 cannot be sufficiently washed away.

In this embodiment, since the supply pipe 92 is configured to be rotatable about its axial direction, the direction of fluid discharge from the sand collecting nozzle 91 can be changed freely. In FIG. 7A, the sand collection nozzle 91 whose discharge direction of the fluid discharged from the discharge port 911 is adjusted in accordance with the position of the recessed wall portion Wa2 is shown by a two-dot chain line. In the sand collecting nozzle 91 shown by the two-dot chain line, the discharge direction of the fluid discharged from the discharge port 911 is directed outward in the pond width direction from the direction directly downward from the center of the supply pipe 92 (vertical direction). There is. By adjusting the discharge direction of the fluid discharged from the discharge port 911 according to the distance from the supply pipe 92 to the left side wall Wa, the supply pipe 92 and the left side wall Wa are adjusted as shown in the second region 92b (see FIG. 6). Even if they are separated from each other, the sand accumulated near the left side wall Wa can be sufficiently washed away. In addition, in this embodiment, since the main pipe 93 and the supply pipe 92 or the supply pipes 92 are connected using the lap joint 934 and the free flange 935, the connected supply pipe 92 can be freely moved around its axis. Can be rotated in stages. Since it can be rotated steplessly, the supply pipe 92 (third region 92c) located at a position facing the inclined wall Wa3 (see FIG. 2) between the convex wall Wa1 and the concave wall Wa2 can rotate as shown in FIG. ) The discharge direction of the fluid can also be set to an intermediate direction between the discharge direction of the sand collection nozzle 91 shown by a solid line and the discharge direction of the sand collection nozzle 91 shown by a two-dot chain line.

Furthermore, in this embodiment, since the main pipe 93 is provided with the branch pipe 932, one main pipe 93 has a total of three pipes: the upstream supply pipe 921, the intermediate supply pipe 922, and the downstream supply pipe 923. Supply pipes 92 are connected to the sand settling basin 2 in parallel in the longitudinal direction. On the other hand, when there is no branch pipe 932 and the supply pipe 92 is connected to a single pipe 931, there are only two supply pipes 92 at most in the longitudinal direction of the sand settling basin 2 for one main pipe 93. can not connect. That is, there are two supply pipes, one extending from the tip of the main pipe 93 to the upstream side of the sand settling basin 2 and the other extending to the downstream side. The discharge direction of the fluid discharged from the discharge port 911 can be set for each supply pipe 92. Therefore, compared to the case where there is no branch pipe 932, when the branch pipe 932 is provided, the discharge direction of the fluid discharged from the discharge port 911 can be adjusted at many points in the longitudinal direction of the sand settling basin 2. It becomes possible to respond flexibly to the shape of the side wall W.

FIG. 7(b) is a cross-sectional view similar to FIG. 7(a) showing the bottom surface near the upstream end of the sand settling basin and the bottom surface near the sand collecting pit. The side walls and bottom plane are also shown in FIG. 7(b).

As described above, the bottom plane 71 is inclined downward by about 1 degree toward the sand collection pit 6 so that the end on the sand collection pit 6 side is the deepest (see FIG. 4 reference). Therefore, the bottom plane 71 exists at a lower position near the sand collection pit 6 than the bottom plane 71 near the upstream end of the sand settling basin 2 . In FIG. 7B, the bottom plane 71 near the upstream end of the sand settling basin 2 is shown by a solid line, and the bottom plane 71 near the sand collection pit 6 is shown by a two-dot chain line. As shown in the figure, even if the fluid is discharged from the discharge port 911 located at the same position, the upstream end of the sand settling basin 2 and the vicinity of the sand collecting pit 6 are located in the height direction of the bottom plane 71. Since the positions are different, a difference in distance Y occurs at the point where the ejected fluid reaches the bottom plane 71. Especially in the sand settling tank 2, which has a long length in the longitudinal direction, the distance Y becomes long, and even if the discharge direction is optimal for one of the upstream end of the sand settling tank 2 and the vicinity of the sand collection pit 6, it is inefficient for the other. It may end up being in the discharge direction. In this embodiment, since the direction in which the fluid is discharged from the discharge port 911 can be changed, the fluid can be discharged in the optimal direction corresponding to the depth of the bottom plane 71 (the height from the supply pipe 92 to the bottom plane 71). can be discharged.

FIG. 7(c) is a cross-sectional view similar to FIG. 7(a) for explaining the change in the discharge direction by the sand collecting nozzle. The side walls and bottom plane are also shown in FIG. 7(c).

As shown in FIG. 7(c), the sand collection nozzle 91 is bent at the middle portion, and in the state shown by the solid line, is formed in an inverted dogleg shape when viewed in the longitudinal direction. Since it is formed in an inverted dogleg shape, if the sand collection nozzle 91 shown by the solid line is rotated 180 degrees around the axis L of the attachment part with the supply pipe 92, it will become as shown by the two-dot chain line. , the fluid discharge direction can be changed from the center side in the pond width direction to the outside in the pond width direction. By forming the sand collecting nozzle 91 in an inverted dogleg shape and configuring the connecting portion between the sand collecting nozzle 91 and the supply pipe 92 to be rotatable, it is possible to change the fluid discharge direction for each discharge port 911. become. That is, the shape of the sand collecting nozzle 91 and the configuration in which the sand collecting nozzle 91 is rotatable relative to the supply pipe 92 in this embodiment correspond to an example of the individual direction changing means.

FIG. 8 is a water supply system diagram in a sewage treatment facility.

As shown in FIG. 8, the water supply pump 33 pumps water from the pump well 3 through a stirring nozzle 62, a pit sand collection nozzle 63, an upstream trough first nozzle 831, an upstream trough second nozzle 832, a downstream trough nozzle 84, and selectively supplied to the sand collection means 9. The water supply pipe 34 connected to the water supply pump 33 includes a supply switching valve Va for switching whether or not to supply fluid to each nozzle and the sand collection means 9 side described above, and a pump well for the fluid sucked up by the water supply pump. A relief switching valve Vb for switching whether or not to return to 3 is provided. A conduit between the supply switching valve Va and the stirring nozzle 62 is provided with a stirring switching valve Vc that switches whether or not to supply fluid to the stirring nozzle 62. A pit sand collection switching valve Vd that switches whether or not to supply fluid to the pit sand collection nozzle 63 is provided in the pipeline between the supply switching valve Va and the pit sand collection nozzle 63. An upstream trough first switching valve Ve1 that switches whether or not to supply fluid to the upstream trough first nozzle 831 is provided in the pipeline between the supply switching valve Va and the upstream trough first nozzle 831. An upstream trough second switching valve Ve2 that switches whether or not to supply fluid to the upstream trough second nozzle 832 is provided in the pipeline between the supply switching valve Va and the upstream trough second nozzle 832. A downstream trough switching valve Vf that switches whether or not to supply fluid to the downstream trough nozzle 84 is provided in the pipeline between the supply switching valve Va and the downstream trough nozzle 84. In addition, in each pipe line between the supply switching valve Va and each nozzle header 9a, 9b, 9c, 9d, 9e, 9f of the sand collection means 9, each nozzle header 9a, 9b, 9c, 9d, 9e, 9f is provided. Sand collection switching valves Vg1, Vg2, Vg3, Vg4, Vg5, and Vg6 for switching whether or not to supply fluid are provided, respectively. These switching valves are composed of electromagnetic valves, and opening and closing of the valves are controlled by a control device (not shown).

FIG. 9 is an explanatory diagram showing the water level of the settling basin and the water level sensor.

As shown in FIG. 9, a water level sensor 99 is arranged in the sand collection pit 6 of the sand settling basin 2. This water level sensor 99 detects the first high water level HHWL when the water level of the sand settling basin 2 is above the upper end 6c of the sand collecting pit 6, and the lower end of the main trough 8 when the water level is below the upper end 6c of the sand collecting pit 6. A second high water level HWL located above 8a, a low water level LWL whose water level is below the sand collection pit 6, an intermediate water level MWL between the second high water level HWL and the low water level LWL, and a low water level LWL. It detects and outputs that the interlock water level has reached an even lower interlock water level LLWL.

The operation of the sewage treatment facility 1 having the above-described configuration will be explained with reference to FIGS. 1, 2, and the like. At a predetermined time when a certain amount of sand has accumulated at the bottom of the sand settling basin 2, the sewage treatment facility 1 performs an operation to remove the accumulated sand. This period may be regular, such as once a month, or may be when the total flow of wastewater flowing into or discharged from the settling basin 2 reaches a certain amount. In the sand removal operation, first, the inflow gate 42 of the dam device 4 shown in FIG. Next, the pump 31 is driven to lower the water level in the settling basin 2. When the water level in the pump well 3 drops to a predetermined value, the lift pump 31 is stopped. Then, the water supply pump 33 is driven for several minutes to discharge fluid from the stirring nozzle 62 shown in FIG. After the water supply pump is stopped, the sand pump 61 is driven. When the water level in the sand settling basin 2 falls to the second high water level HWL (see FIG. 9), the water supply pump 33 is driven again to discharge fluid from the stirring nozzle 62 shown in FIG. 2. Thereafter, this sand pump 61 stops driving according to the output from the water level sensor 99 indicating the low water level LWL (see FIG. 9), and starts driving according to the output indicating the second high water level HWL (see FIG. 9). Control to restart is automatically executed. On the other hand, the water supply pump 33 shown in FIG. 1 continues to be driven until the sand removal operation is completed. The sand poured into the sand collection pit 6 is carried by the sand pump 61 to a sand separator (not shown) outside the sand settling basin 2 while the sand pump 61 is operating. Note that if the water level sensor 99 detects that the water level has reached the first high water level HHWL or the interlock water level LLWL (see Figure 9), it is considered that some abnormality has occurred, so an alert is displayed and the sewage treatment facility 1 Stop the sand removal operation.

After that, fluid is discharged for a certain period of time from the stirring nozzle 62, the first upstream trough nozzle 831, and the second upstream trough nozzle 832 shown in FIG. is poured into the sand collection pit 6. After a certain period of time has elapsed, the discharge of fluid from the agitation nozzle 62, the first upstream trough nozzle 831, and the second upstream trough nozzle 832 is stopped, and a constant amount of fluid is discharged from the discharge port 911 (see FIG. 6) provided in the fifth nozzle header 9e. Discharge fluid for a time. This discharge allows the sand accumulated on the bottom surface 7 between the right side wall Wb near where the fifth nozzle header 9e is arranged and the upstream second main trough 816 to flow into the upstream second main trough 816. can. After a certain period of time has elapsed, the ejection of fluid from the ejection port 911 provided in the fifth nozzle header 9e is stopped. Then, fluid is discharged from the stirring nozzle 62 and the upstream trough second nozzle 832 for a certain period of time, and the sand flowing into the upstream second main trough 816 is sent to the sand collecting pit 6. Thereafter, the discharge of fluid from the stirring nozzle 62 and the second upstream trough nozzle 832 is stopped, and the fluid is discharged for a certain period of time from the discharge port 911 provided in the second nozzle header 9b. In this embodiment, the discharge port 911 in the vicinity of the recessed wall Wa2 and the inclined wall Wa3 of the left side wall Wa allows a certain amount of fluid to flow into the left side wall Wa depending on the distance from the supply pipe 92 to the left side wall Wa. The direction of fluid discharge is adjusted so that the fluid reaches the target. Therefore, all the sand accumulated on the bottom surface 7 between the left side wall Wa near where the second nozzle header 9b is arranged and the upstream side first main trough 815 can be flowed to the upstream side first main trough 815. can. After a certain period of time has elapsed, the ejection of fluid from the ejection port 911 provided in the second nozzle header 9b is stopped. Then, fluid is discharged from the stirring nozzle 62 and the first upstream trough nozzle 831 for a certain period of time, and the sand flowing into the first upstream main trough 815 is sent to the sand collecting pit 6. After that, similarly to the above-described operation, the fluid is discharged in the order of the fourth nozzle header 9d, the stirring nozzle 62, the upstream trough second nozzle 832, the first nozzle header 9a, the stirring nozzle 62, and the upstream trough first nozzle 831. All the sand deposited on the bottom of the pond on the upstream side of the sand collecting pit 6 is carried out to the outside of the settling basin 2. Note that the order in which fluid is discharged from each nozzle header 9a, 9b, 9d, and 9e may be any order. However, if the sand accumulated on the side far from the sand collection pit 6 is flushed first, the sand accumulated on the side closer to the sand collection pit 6 will flow into the main trough 8 together with the sand to be flushed, and the sand will be deposited in the main trough. may accumulate, making it difficult to send the sand in the main trough 8 to the sand collection pit 6. Therefore, after the fluid is discharged from the second nozzle header 9b and the fifth nozzle header 9e on the side closer to the sand collection pit 6, the fluid is discharged from the first nozzle header 9a and the fourth nozzle header 9d on the side far from the sand collection pit 6. It is desirable to discharge.

After the sand accumulated on the upstream side is removed by the above-described operation, fluid is discharged from the stirring nozzle 62 and the downstream trough nozzle 84 for a certain period of time to flow the sand accumulated on the downstream main trough 82 into the sand collecting pit 6. Thereafter, the discharge of fluid from the stirring nozzle 62 and the downstream trough nozzle 84 is stopped, and the fluid is discharged for a certain period of time from the discharge port 911 provided in the sixth nozzle header 9f. After a certain period of time has elapsed, the discharge of fluid from the discharge port 911 provided in the sixth nozzle header 9f is stopped. Then, fluid is discharged from the stirring nozzle 62 and the downstream main trough 82 for a certain period of time, and the sand flowing into the downstream main trough 82 is sent to the sand collecting pit 6. Next, in the same manner as described above, by discharging fluid from the third nozzle header 9c, the stirring nozzle 62, and the downstream trough nozzle 84 in this order, all the sand accumulated on the bottom of the pond downstream from the sand collection pit 6 is settled. It is carried out to the outside of pond 2. Finally, by discharging fluid from the pit sand collection nozzle 63, the sand accumulated on the sand collection pit slope 6b is flowed into the sand collection pit 6. When all these operations are completed, the water supply pump 33 is stopped, and after a predetermined period of time, the sand pump 61 is also stopped.

Note that in this embodiment, when the sand removal operation described above is being performed, the amount of fluid pumped by the sand pump 61 is set to be slightly larger than the amount of fluid pumped by the water supply pump 33. ing. For this reason, the sand pump 61 repeats stopping and restarting multiple times while performing the removing operation. However, if the sand pump 61 is repeatedly driven and stopped, the life of the pump will be shortened due to the rush current at the start of driving. As a countermeasure for this, the change in water level during the sand removal operation may be minimized by bringing the pumping capacity of the water supply pump 33 closer to the fluid pumping capacity of the sand pump 61. Further, when the water level sensor 99 detects that the water level has reached the intermediate water level MWL, fluid may be additionally ejected from other nozzles in addition to the nozzle that is ejecting fluid at that time. By increasing the number of nozzles that discharge fluid, the load (throttling resistance) on the fluid flow is reduced, so the fluid sucked up by the water supply pump 33 increases, and as a result, more fluid can be supplied to the sand settling basin 2. This makes it difficult for the water level to reach the low water level LWL, so the number of times the sand pump 61 stops and restarts can be reduced. Here, it is desirable that the other nozzle is the sand collection nozzle 91 provided in the nozzle header that is scheduled to discharge the sand next. By discharging the fluid from the nozzle header that is scheduled to be discharged next, it is possible to preliminarily flush out the sand on the bottom surface that will be discharged next, so that it is possible to further suppress the remaining sand. Moreover, the fluid to be additionally discharged may be fluid stored in other equipment. Furthermore, even if the water level reaches the low water level LWL, the sand pump 61 is not stopped, and instead of stopping, the fluid pumped up by the water supply pump 33 and the fluid stored in other equipment are supplied to the sand settling basin 2. may be configured. When configured in this way, the supply of fluid stored in other equipment to the sand settling basin 2 may be stopped when the second high water level HWL is reached. By reducing the number of times that the sand pump 61 repeats stopping and driving, it is possible to suppress deterioration of the sand pump 61 and extend its life.

By the way, in this embodiment, the discharge port 911 is arranged near the bottom of the sand settling basin 2. On the other hand, for example, in Japanese Patent Laid-Open No. 2011-245391, a sand collecting means 9 having a discharge port 911 is disposed in the upper part of the sand settling basin 2, and fluid is discharged toward the side wall W, so that the wall surface of the side wall W is covered with the fluid. A sand settling pond 2 has been proposed in which the sand flows down.

FIG. 10 is a cross-sectional view of the sand settling basin similar to FIG. 4, showing a case where the sand collecting means is arranged in the upper part of the sand settling basin and a case where the sand collecting means is arranged near the bottom of the sand settling basin. In this FIG. 10, the sand collection means arranged in the upper part of the sand settling basin is shown by a chain double-dashed line. Moreover, among the lines indicating the piping and the side walls, the lines that intersect with the sand collection means arranged in the upper part of the sand settling basin are shown with the intersecting portions omitted.

In FIG. 10, a virtual upper nozzle header 90 is shown in the upper part of the sand settling basin 2. As shown in FIG. This upper nozzle header 90 is used in place of the first nozzle header 9a shown in FIG. At the upstream end of the sand settling basin 2, a dust remover 5 that stands obliquely is arranged. The sand collecting means 9 needs to be arranged so as not to interfere with the dust remover 5. Therefore, the upper nozzle header 90 arranged in the upper part of the sand settling tank 2 is located on the downstream side compared to the case where it is arranged near the bottom of the sand settling tank 2 as shown in FIG. In other words, the upper nozzle header 90 has to be placed downstream of the first nozzle header 9a by a distance S. As described above, the upper portions of the endless chain 51 and the filtration screen 53 that constitute the dust remover 5 overlap the bottom surface 7 and the main trough 8 in the longitudinal direction. Therefore, even if fluid is discharged from the upper nozzle header 90, there will be a portion of the bottom plane 71 on the most upstream side where the discharged fluid does not reach. If the dust remover 5 and the upper nozzle header 90 are disposed upstream by a distance S than shown in FIGS. 4 and 10, the fluid can reach the most upstream portion of the bottom plane 71. However, with this arrangement, the length of the settling basin 2 in the longitudinal direction becomes long. As a result, the sand settling tank 2 becomes large, requiring a large amount of land to install the sand settling tank 2, and the sand settling tank 2 becomes expensive. In the sand settling tank 2 of this embodiment, the first nozzle header 9a is arranged near the bottom of the sand settling tank 2, so compared to the case where the upper nozzle header 90 arranged in the upper part of the sand settling tank 2 is used. This has the effect of suppressing the increase in size of the sand settling tank 2 and providing the sand settling tank 2 at a low cost.

Next, a modification of the connection surface 73 will be described. In the modified examples described below, differences from the embodiment shown in FIGS. 1 to 9 will be mainly explained, and components having the same names as those in the embodiment shown in FIGS. 1 to 9 will be described. will be explained using the reference numerals used so far, and redundant explanations will be omitted.

FIG. 11 is a sectional view similar to FIG. 3 showing a modification of the connection surface.

This modification differs from the example shown in FIG. 3 in that the connection surface 73 is formed into a curved surface. The connection surface 73 includes a ridgeline portion 731 extending in the longitudinal direction, a first connection surface 732, and a second connection surface 733. As shown in FIG. 11, the first connection surface 732 and the second connection surface 733 have a quadrant arc shape in cross section. In other words, the connecting surface 73 is formed as a semi-cylindrical surface that projects upward as a whole. The ridgeline portion 731 is constituted by a line at the upper end of the cylindrical shape. In this modification as well, as in the example shown in FIG. 3, the sand that settles on the connection surface 73 in the waste water in the settling basin 2 tends to slide off the connection surface 73 due to its own weight. However, since the angle of inclination of the tangential plane of the connection surface 73 becomes gentle near the ridgeline portion 731, there is a risk that sand may remain in the vicinity. On the other hand, since the thickness of the concrete constituting the connection surface 73 in the pond width direction is thick even in the vicinity of the ridgeline portion 731, there is an effect that the ridgeline portion 731 portion is less likely to be damaged. Note that one of the first connecting surface 732 and the second connecting surface 733 is formed into a flat shape as in the example shown in FIG. 3, and the other is formed in a curved shape as in the modified example shown in FIG. may be formed. Furthermore, one or both of the first connecting surface 732 and the second connecting surface 733 may be formed into a surface that is a combination of a curved surface and a flat surface.

Next, a modification of the sand collecting means 9 will be explained. In the modified examples described below, differences from the embodiment shown in FIGS. 1 to 9 will be mainly explained, and components having the same names as those in the embodiment shown in FIGS. 1 to 9 will be explained. will be explained using the reference numerals used so far, and redundant explanations will be omitted.

12(a) is a diagram showing a first modification of the supply pipe and sand collection nozzle shown in FIG. 7, and FIG. 12(b) is a diagram showing a second modification of the supply pipe and sand collection nozzle shown in FIG. FIG.

In the first modification, a lap joint 934 is not arranged in the supply pipe 92, the supply pipe 92 and the branch pipe 932 are joined by a flange, and a ball joint 912 is provided in the sand collecting nozzle 91. This point differs from the example shown in FIG. 7(a). In FIG. 12A, the sand collecting nozzle 91 corresponding to the convex wall portion Wa1 is shown by a solid line, and the sand collecting nozzle 91 corresponding to the recessed wall portion Wa2 is shown by a two-dot chain line. In this modification, a ball joint 912 is provided between the supply pipe 92 and each discharge port 911. This ball joint 912 allows the fluid discharge direction to be changed steplessly not only in the direction of rotation about the axis of the supply pipe 92 but also in various other directions. Therefore, the ejection direction can be finely adjusted for each ejection port 911. Note that a lap joint 934 may be arranged on the supply pipe 92 and a ball joint 912 may be further provided on the sand collection nozzle 91. In this case, the lap joint 934 corresponds to an example of a collective change means, and the ball joint 912 corresponds to an example of an individual direction change means.

In the second modification, the lap joint 934 is not arranged in the supply pipe 92, the supply pipe 92 and the branch pipe 932 are joined by a flange, and the sand collection nozzle 91 is arranged in the circumferential direction of the supply pipe 92. This example differs from the example shown in FIG. 7A in that a plurality of mounting portions 924 are formed. In FIG. 12(b), the sand collecting nozzle 91 corresponding to the convex wall portion Wa1 is shown by a solid line, and the sand collecting nozzle 91 corresponding to the recessed wall portion Wa2 is shown by a two-dot chain line. In this modification, the mounting portions 924 of the sand collection nozzle 91 are formed at six locations in the circumferential direction of the supply pipe 92. Thereby, after the supply pipe 92 is fixed to the branch pipe 932, the sand collection nozzle 91 can be attached to any one of the six attachment parts 924. In addition, before the sand collection nozzle 91 is attached, plug members are attached to all the attachment parts 924. When installing the sand collecting nozzle 91, the plug member is removed before installing the sand collecting nozzle 91. Note that a lap joint 934 may be disposed on the supply pipe 92 and a mounting portion 924 may be further formed on the supply pipe 92. In this case, the lap joint 934 corresponds to an example of a collective change means, and the mounting part 924 corresponds to an example of an individual direction change means. In this modification, six mounting portions 924 are formed in the circumferential direction, but the number of mounting portions 924 may be two to five, or seven or more.

The present invention is not limited to the above-described embodiments and modifications, but can be modified in various ways within the scope of the claims. For example, in this embodiment, the present invention is used in the settling basin 2 of the sewage treatment facility 1 into which sewage and rainwater flows, but it can also be applied to the settling basin in the rainwater treatment facility into which only rainwater flows. Furthermore, in the present embodiment, after the sand accumulated on the bottom surface 7 on the upstream side of the sand collection pit 6 is washed away, the sand accumulated on the bottom surface 7 on the downstream side of the sand collection pit 6 is washed away. Sand accumulated on the bottom surface 7 on the downstream side may be washed away. Further, in this embodiment, an example was shown in which the dust remover 5 and the protruding wall 10 were arranged at the upstream end of the settling basin 2, but the dust removing machine 5 and the protruding wall 10 were arranged at the downstream end of the settling basin 2. You may. When the dust remover 5 and the protruding wall 10 are arranged at the downstream end of the sand settling basin 2, two downstream main troughs 82 are provided and arranged on the left side wall Wa side and the right side wall Wb side with respect to the protruding wall 10, respectively. do it. Then, the ridgeline portion, the first connecting surface, and the second connecting surface may be formed between the two downstream main troughs 82 except for the area where the protruding wall 10 is provided.

According to this embodiment or its modification, the sand deposited on the bottom surface 7 can be flushed away with a fluid without remaining. Moreover, since the linear supply pipe 92 can be used even in a sand settling basin in which the left side wall Wa or the right side wall Wb is not formed in a straight line, the sand settling basin 2 can be provided at low cost. In addition, even if the shape of the side wall W is unknown when designing the settling basin 2 or creating the supply pipe 92, the discharge direction can be adjusted when constructing the settling basin 2, so it can be applied to various shapes of the settling basin 2. Able to respond flexibly. Furthermore, the sand that has settled on the connection surface 73 slides down the first connection surface 732 or the second connection surface 733 and is deposited on the upstream first main trough 815 or the upstream second main trough 816, Sand does not remain between the main trough 815 and the upstream second main trough 816. In addition, in this embodiment, the inclination angle of the first bottom surface 711 and the second bottom surface 712 is set to a gentle inclination angle (approximately 5 degrees) that allows the accumulated sand to be flowed away by the fluid discharged from the discharge port 911. There is. Thereby, the settling basin 2 can be created without digging deeply into the ground. On the other hand, by making the connection surface 73 at a steeper angle than the first bottom surface 711 and the second bottom surface 712, the fluid discharged from the discharge port 911 does not reach the connection surface 73. The sand that has settled can be deposited in the upstream first main trough 815 or the upstream second main trough 816.

The following inventive concept can also be extracted from the sand settling basin of this embodiment.

In the settling pond where the sand contained in the received water settles,
A groove provided at the bottom of the pond below the side wall and extending in a predetermined direction;
a bottom surface provided at the bottom of the pond and connected to the groove;
a plurality of discharge ports that discharge fluid for flowing sand settled on the bottom surface from the side wall side toward the groove;
and a supply pipe provided with the discharge port,
The plurality of discharge ports include those that discharge fluid toward the center in the pond width direction from the axis of the supply pipe in which the discharge ports are provided, and those that discharge fluid toward the outside in the pond width direction from the axis of the supply pipe. A settling pond characterized by having a part that discharges fluid.

Furthermore, the following inventive concept can be extracted from the sand settling basin of this embodiment.

In the settling pond where the sand contained in the received water settles,
A groove provided at the bottom of the pond below the side wall and extending in a predetermined direction;
a bottom surface provided at the bottom of the pond and connected to the groove;
a discharge port for discharging a fluid for flowing sand settled on the bottom surface from the side wall side toward the groove;
A sand settling basin characterized in that the discharge direction of the fluid discharged from the discharge port can be changed.

In this settling basin,
a supply pipe provided with the discharge port;
a main pipe that supplies fluid to the supply pipe;
The supply pipe may be rotatable with respect to the main pipe around the axial direction of the supply pipe.

In addition, in the above-mentioned settling basin,
The supply pipe may include a plurality of discharge ports.

Furthermore, in the above-mentioned settling basin,
having a supply pipe provided with the discharge port;
The discharge port may be capable of changing the fluid discharge direction by a ball joint disposed between the supply pipe and the discharge port.

In addition, in the above-mentioned settling basin,
The discharge port has a supply pipe provided in a detachable manner,
The supply pipe may have a plurality of mounting parts to which the discharge ports are mounted in a circumferential direction of the supply pipe.

Furthermore, the following inventive concept can be extracted from the sand settling basin of this embodiment.

In the settling pond where the sand contained in the received water settles,
A groove provided at the bottom of the pond below the side wall and extending in a predetermined direction;
a bottom surface provided at the bottom of the pond and connected to the groove;
a discharge port for discharging fluid for flowing sand settled on the bottom surface from the side wall toward the groove; and a plurality of discharge ports arranged in the center in the pond width direction relative to the side wall, and the plurality of discharge ports are arranged in the predetermined direction. and a supply pipe;
The supply pipe has a first region extending from the side wall in the pond width direction at a first interval, and a second region extending from the side wall in the pond width direction at a second interval. ,
A sand settling basin characterized in that a discharge port arranged in the first region and a discharge port arranged in the second region are capable of changing a fluid discharge direction independently of each other.

The number of discharge ports provided in the first region may be plural or one. When a plurality of discharge ports are provided in the first region, it is preferable that the direction of fluid discharge from these discharge ports can be changed all at once. Further, the number of ejection ports provided in the second region may be plural or may be one. Even when there is a plurality of discharge ports provided in the second region, it is preferable that the direction of fluid discharge from these discharge ports can be changed all at once. Here, "can be changed all at once" means, for example, that the first region and the second region of the supply pipe can be rotated separately around the axial direction of the supply pipe. This is achieved by doing. In addition, rotatable portions may be provided at both end portions of the first region of the supply pipe, and rotatable portions may be provided at both end portions of the second region. Note that the supply pipe may be a straight pipe or may be a pipe provided with a somewhat curved portion.

The supply pipe is provided with a third region connecting the first region and the second region,
The discharge port provided in the third region is capable of changing the fluid discharge direction separately from the discharge port provided in the first region and the discharge port provided in the second region. Good too.

The third region may be an inclined region where the distance from the side wall gradually changes in the extending direction, or may be a region where the distance from the side wall changes gradually.

Further, the number of ejection ports provided in the third region may be plural or may be one. When there is a plurality of discharge ports provided in the third region, it is preferable that the direction of fluid discharge from those discharge ports can also be changed all at once. "Can be changed all at once" as used herein means, for example, that the portion of the third region of the supply pipe is changed separately from the portion of the first region and the portion of the second region of the supply pipe. This is achieved by rotating around the axial direction.

Furthermore, the following inventive concept can be extracted from the sand settling basin of this embodiment.

In the settling pond where the sand contained in the received water settles,
A groove provided at the bottom of the pond below the side wall and extending in a predetermined direction;
a bottom surface provided at the bottom of the pond and connected to the groove;
a plurality of discharge ports disposed opposite to the side wall for discharging a fluid for causing sand settled on the bottom surface to flow from the side wall toward the groove;
The side wall has a convex wall portion that protrudes toward the center in the pond width direction and extends in the predetermined direction, and a recessed wall portion that is recessed toward the outside in the pond width direction and extends in the predetermined direction,
The discharge port is arranged to face each of the convex wall portion and the concave wall portion,
The discharge direction of the fluid discharged from the discharge port disposed opposite to the concave wall portion is different from the discharge direction of the fluid discharged from the discharge port disposed opposite the convex wall portion. A settling pond characterized by being equipped with a changeable direction change means.

Furthermore, the following inventive concepts can also be extracted from the sand settling basin of this embodiment.

In the settling pond where the sand contained in the received water settles,
A groove provided at the bottom of the pond below the side wall and extending in a predetermined direction;
a bottom surface provided at the bottom of the pond and connected to the groove;
a supply pipe arranged opposite to the side wall and extending in the predetermined direction;
a plurality of discharge ports disposed in the supply pipe and discharging a fluid for flowing sand settled on the bottom surface from the side wall side toward the groove;
The side wall has a convex wall portion that protrudes toward the center in the pond width direction and extends in the predetermined direction, and a recessed wall portion that is recessed toward the outside in the pond width direction and extends in the predetermined direction,
The discharge port is disposed at a position facing the convex wall portion and a position facing the concave wall portion, respectively,
The supply pipe is arranged between a discharge port disposed at a position opposite to the convex wall portion and a discharge port disposed at a position opposite to the concave wall portion, the discharge direction of the fluid discharged from the discharge port. A settling basin characterized in that it is equipped with a direction change means that can change the direction.

Also, in this settling basin,
The side wall has an inclined wall part formed between the convex wall part and the recessed wall part and extending in a direction inclined with respect to the predetermined direction and the pond width direction,
The discharge port is also arranged at a position opposite to the inclined wall portion,
The supply pipe is arranged between a discharge port disposed opposite to the convex wall portion and a discharge port disposed opposite to the inclined wall portion so as to direct the discharge direction of the fluid discharged from the discharge port. comprising a changeable first direction changing means,
The discharge direction of the fluid discharged from the discharge ports can be changed between the plurality of discharge ports arranged opposite to the recessed wall portion and the discharge ports arranged opposite to the inclined wall portion. It may also include a second direction changing means.

In addition, the following inventive concept can be extracted from the sand settling basin of this embodiment.

In the settling pond where the sand contained in the received water settles,
A groove provided at the bottom of the pond below the side wall and extending in a predetermined direction;
a bottom surface provided at the bottom of the pond and connected to the groove;
a plurality of discharge ports that discharge fluid for flowing sand settled on the bottom surface from the side wall side toward the groove;
collective direction changing means capable of collectively changing the discharge direction of fluid discharged from at least two of the plurality of discharge ports;
A sand settling basin characterized by comprising: individual direction changing means capable of changing the discharge direction of the fluid discharged from the discharge ports for each discharge port.

Furthermore, the following inventive concept can be extracted from the sand settling basin of this embodiment.

In a settling basin, the received water is allowed to flow down in a direction perpendicular to the width direction of the pond between one side wall and the other side wall constituting the end face in the width direction of the pond, and the sand contained in the water is settled.
a first groove and a second groove provided at the bottom of the pond and extending in the orthogonal direction at intervals in the pond width direction;
a sand collection pit provided at the bottom of the pond, to which the first groove is connected and the second groove is connected;
a protruding wall formed between the first groove and the second groove and protruding upward from the pond bottom;
A ridgeline portion extending along the orthogonal direction in a portion of the pond bottom between the first groove and the second groove and between the sand collection pit and the protruding wall; A sand settling basin characterized in that a first connecting surface connecting the first groove and a second connecting surface connecting the ridgeline portion and the second groove are formed.

Furthermore, the following inventive concept can be extracted from the sand settling basin of this embodiment.

In a settling basin, the received water is allowed to flow down in a direction perpendicular to the width direction of the pond between one side wall and the other side wall constituting the end face in the width direction of the pond, and the sand contained in the water is settled.
a first groove and a second groove provided at the bottom of the pond and extending in the orthogonal direction at intervals in the pond width direction;
a protruding wall formed between the first groove and the second groove and protruding upward from the pond bottom;
A ridgeline portion extending along the orthogonal direction in a portion of the pond bottom between the first groove and the second groove excluding a region where the protruding wall is provided; A sand settling basin characterized in that a first connecting surface connecting the first groove and a second connecting surface connecting the ridgeline portion and the second groove are formed.

Further, in this settling basin, the first connecting surface is an inclined surface that slopes downward from the ridgeline toward the first groove,
The second connection surface may be an inclined surface that slopes downward from the ridgeline toward the second groove.

According to this inventive concept, it is possible to provide a sand settling basin that can collect settled sand in the groove without leaving it on the bottom surface.

The sand settling basin described above allows the received water to flow down in a direction perpendicular to the width direction of the pond between one side wall and the other side wall that constitute the end face in the width direction of the pond, and removes the sand contained in the water. In the settling basin that settles
a first groove and a second groove provided at the bottom of the pond and extending in the orthogonal direction at intervals in the pond width direction;
a protruding wall formed between the first groove and the second groove and protruding upward from the pond bottom;
a sand collection pit provided at the bottom of the pond, to which the first groove is connected and the second groove is connected;
A ridgeline extending along the orthogonal direction in a portion of the pond bottom between the first groove and the second groove, connected to the protruding wall and continuous from the protruding wall to the sand collection pit. a first connection surface that connects the ridgeline portion and the first groove, and a second connection surface that connects the ridgeline portion and the second groove,
The first connection surface is an inclined surface that slopes downward from the ridgeline toward the first groove,
The second connection surface is characterized in that it is an inclined surface that slopes downward from the ridgeline toward the second groove.

Here, the first connecting surface and the second connecting surface may be a flat surface, a curved surface, or a composite surface of a flat surface and a curved surface. Moreover, one of the first connection surface and the second connection surface may be a vertical surface.

According to this settling basin, the basin bottom between the first groove and the second groove is composed of a first connecting surface and a second connecting surface connected to the respective grooves with the ridgeline section as the top. Sand that has settled on the connecting surfaces of the grooves tends to slide down the connecting surfaces due to its own weight and collect in each groove.

By forming the first connecting surface and the second connecting surface into inclined surfaces that slope downward toward the groove, sand that settles between the first groove and the second groove can be removed from the inside of the first groove and the second groove. It can be distributed and deposited. This can prevent sand from accumulating in only one groove, increasing the transport resistance of the sand within the groove and making it difficult to transport the sand within the groove.

Furthermore, in this settling basin, the first groove is provided on the one side wall side,
The second groove is provided on the other side wall,
a first bottom surface formed between the one side wall and the first groove and inclined downward toward the first groove;
a second bottom surface formed between the other side wall and the second groove and inclined downward toward the second groove;
The angle of inclination of each of the first connection surface and the second connection surface may be steeper than the angle of inclination of the first bottom surface and the second bottom surface.

If the inclination angles of the first and second bottom surfaces are different, the inclination angle of the steeper one of those bottom surfaces is used for comparison, and the inclination angle of the first and second connection surfaces is If they are different, the inclination angle of the connection surface with a gentler inclination may be used for comparison. By making the inclination angle of the first connecting surface and the second connecting surface steeper than the first bottom surface and the second bottom surface, the sand settled between the first groove and the second groove can be removed into the first groove or the second connecting surface. 2.It can be slid down securely into the groove.

Further, in this sand settling basin, a first discharge port that discharges a fluid for flowing sand settled on the first bottom surface from the one side wall side toward the first groove;
The second bottom surface may include a second outlet for discharging a fluid for causing the sand settled on the second bottom surface to flow from the other side wall toward the second groove.

According to this aspect, even if the slope of the first bottom surface and the second bottom surface is gentle, the sand deposited on the first bottom surface and the second bottom surface is removed by the fluid discharged from the first discharge port and the second discharge port. It can flow into one groove or into a second groove.

Further, in this settling basin, two dust removers are arranged between the one side wall and the protruding wall and between the other side wall and the protruding wall to remove contaminants contained in the received water. may be provided.

Since the dust remover can be arranged with a short length in the pond width direction, damage to the dust remover can be suppressed even if the amount and flow velocity of wastewater flowing into the settling basin increase. In addition, the dust remover may be formed at the upstream end of the sand settling basin, or may be formed at the downstream end of the sand settling basin.

Note that even if the constituent features are included only in the descriptions of the embodiment and each modification described above, the constituent features may be applied to the embodiment and other modifications.

2 Sand settling basin 5 Dust remover 10 Projecting wall 711 First bottom surface 712 Second bottom surface 731 Ridge line portion 732 First connection surface 733 Second connection surface 815 Upstream first main trough 816 Upstream second main trough 911 Discharge port Left side wall Wa
Right side wall Wb

Claims (2)

In a settling basin, the received water is allowed to flow down in a direction perpendicular to the width direction of the pond between one side wall and the other side wall constituting the end face in the width direction of the pond, and the sand contained in the water is settled.
a first groove and a second groove provided in the pond bottom at intervals in the pond width direction;
a protruding wall formed between the first groove and the second groove and protruding upward from the pond bottom;
A ridgeline portion extending along the orthogonal direction between the first groove and the second groove in the pond bottom portion, a first connection surface connecting the ridgeline portion and the first groove; A second connection surface connecting the ridgeline portion and the second groove is connected to the protruding wall, and
The first connection surface is an inclined surface that slopes downward from the ridgeline toward the first groove,
The second connection surface is an inclined surface that slopes downward from the ridgeline toward the second groove,
The first groove is provided on the one side wall side,
The second groove is provided on the other side wall,
a first bottom surface formed between the one side wall and the first groove and inclined downward toward the first groove;
a second bottom surface formed between the other side wall and the second groove and inclined downward toward the second groove;
A sand settling basin, wherein each of the first connecting surface and the second connecting surface has a steeper angle of inclination than the first bottom surface and the second bottom surface. a first discharge port that discharges a fluid for flowing sand settled on the first bottom surface from the one side wall side toward the first groove;
2. The sand settling basin according to claim 1, further comprising a second outlet for discharging a fluid for causing the sand settled on the second bottom surface to flow from the other side wall toward the second groove.

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