JP2023168406A - Sand sedimentation pond - Google Patents

Abstract

To provide an inexpensive sand sedimentation pond.SOLUTION: A sand sedimentation pond 2 in which sands contained in received water settle to a pond bottom, comprises: a main trough 8 which is provided on the pond bottom, and extends in a prescribed direction; a trough first discharge port 831a which discharges a fluid in the prescribed direction in water accumulated in the main trough 8; a bottom plane 71 and a small trough 72 which are provided on the pond bottom, are formed between a side wall and the main trough 8 of the sand sedimentation pond 2, and are connected to the main trough 8; a second discharge port 911 which discharges the fluid for flowing sands accumulated on the bottom plane 71 and in the small trough 72 toward the main trough 8 from the side wall side into atmosphere; a first covering member 13 which covers circumference of a virtual axis VL extending in the prescribed direction from a center of the first discharge port 831a, and has an opening 13a at a lower end portion; and a feed water pump 33 which selectively feeds the fluid into the first discharge port 831a and the second discharge port 911. The second discharge port 911 discharges the fluid at a discharge pressure lower than the first discharge port 831a.SELECTED DRAWING: Figure 5

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 are equipped with a settling basin that collects sand into a sand collection pit at the bottom of the pond and removes it from the wastewater. For example, Patent Document 1 discloses that by performing a sand removal operation at a predetermined time, accumulated sand is collected in a sand collection pit, and the sand is pumped up along with wastewater by a sand pump installed in the sand collection pit. It is disclosed that the sand is transported through a pipe and sent to a sand separator located outside the sand settling basin. This pipe consists of a conveyor pipe that extends above the sand settling basin toward a sand separator installed outside the pond, and a conveyor pipe that extends from the sand pump toward the conveyor pipe that extends above the sand settling basin. It consists of a sand pumping pipe connected to the This sand pumping pipe is provided with a backflow prevention valve to prevent the sewage and sand in the pipe from flowing back into the sand settling pond when the sand pump is not being driven. There are two types of backflow prevention valves: one type that opens and closes using the driving force of an electric actuator (hereinafter referred to as an electric valve), and the other type that opens and closes automatically depending on the flow of fluid (hereinafter referred to as a check valve). There is.

JP2014-95290A

By the way, an inexpensive sand settling basin is desired.

In view of the above circumstances, an object of the present invention is to provide an inexpensive sand settling basin.

The sand settling basin of the present invention, which solves the above object, has the following features:
a groove provided at the bottom of the pond and extending in a predetermined direction;
a first discharge port that discharges fluid in the predetermined direction in the water collected in the groove;
a bottom surface provided at the bottom of the pond, formed between the side wall of the settling basin and the groove, and connected to the groove;
a second discharge port for discharging fluid into the atmosphere for flowing sand accumulated on the bottom surface from the side wall side toward the groove;
a cover member that covers the periphery of the virtual axis extending from the center of the first discharge port toward the predetermined direction and has an opening at a lower end portion;
a pump that selectively supplies fluid to the first discharge port and the second discharge port;
The second discharge port is characterized in that the fluid is discharged at a lower discharge pressure than the first discharge port.

The first discharge port discharges fluid while the inside of the cover member is filled with water received by the settling basin,
The second discharge port may discharge the fluid after draining the water received by the settling basin.

The first discharge port discharges the fluid at a discharge pressure of 0.05 MPa or more and 0.3 MPa or less,
The second discharge port may discharge the fluid at a discharge pressure of 0.0002 MPa or more and 0.005 MPa or less.

According to the present invention, an inexpensive sand settling basin can be provided.

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. (a) is an enlarged view showing the Z section of FIG. 3, and FIG. 4(b) is a schematic perspective view showing the first cover member and the first upstream trough nozzle. FIG. 3 is a sectional view taken along line AA of the sand settling basin shown in FIG. 2. FIG. 6 is an enlarged view showing part B in FIG. 5; (a) is a sectional view for explaining a 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. 3 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. 6, and (b) is a cross-sectional view similar to (a) for explaining the change in the discharge direction by the sand collection nozzle. It is a schematic sectional view of four sewage treatment facilities cut in the pond width direction at a sand collection pit part and seen in the longitudinal direction. It is a skeleton diagram showing a sand pump, a sand pump, a conveyance pipe, and a sand separator. 9(a) is an enlarged view showing section E in FIG. 9, and FIG. 9(b) is an enlarged view of FIG. 9(a) viewed from the upstream side of the transport pipe in the transport direction. It is a water supply system diagram in a sewage treatment facility. It is an explanatory view showing a water level of a settling basin and a water level sensor. It is a flowchart which shows the flow of sand removal operation in a sewage treatment facility. 6 is a sectional view of the sand settling basin similar to FIG. 5, 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. 8, and (b) is a diagram showing a second modification of the supply pipe and sand collection nozzle shown in FIG. 8. be. FIG. 6 is a cross-sectional view similar to FIG. 5 showing a modification of the main trough, the covering member, and the bottom plane. 19 is a sectional view similar to FIG. 8(a) showing a bottom plane near the upstream end of the sand settling basin and a bottom plane near the sand collection pit in the modification shown in FIG. 18. FIG. FIG. 14 is an explanatory diagram similar to FIG. 13 showing an example of water level detection when the height of the main trough is increased.

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. Four sewage treatment facilities 1 of this embodiment are provided in parallel with respect to the flow direction of sewage. Since each of the sewage treatment facilities 1 has a similar configuration, one of them will be explained first. 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 from the dam device 4 from flowing into the settling basin 2. Further, 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 passes through the sand pump 64 and is sent to the sand separator SS (see FIG. 10) provided outside the sand settling basin 2. 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. A lift pump 31 and a water supply pump 33 are arranged in the pump well 3. 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 pond (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 plane 71, a small trough 72, a connecting surface 73, and a main body between the left side wall Wa and the right side wall Wb. The pond is generally rectangular in plan view and includes a trough 8 and sand collection means 9. The bottom plane 71 and the small trough 72 correspond to an example of the bottom surface. Further, the main trough 8 corresponds to an example of a groove. 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 collecting pit 6, the bottom plane 71, the small trough 72, the connecting surface 73, and the main trough 8 are provided at the bottom of the sand settling basin 2, respectively. This bottom plane 71 is formed by the surface of concrete poured at the bottom of the pond. The main trough 8 extends in the longitudinal direction 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 whose rear ends are connected to the sand collecting pit 6, and a second upstream main trough 816. The main trough 82 extends longitudinally from near the downstream end of the pond 2 and has a rear end connected to the sand collection 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 basin 2 discharges fluid into a bottom plane 71 and a small trough 72 after draining the sewage in the settling basin 2, and collects the sand settled in the bottom plane 71 and small trough 72, so-called low-pressure sand collection. This is a sand 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 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. On the other hand, the bottom plane 71 is formed horizontally in the longitudinal direction. 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 made of a stainless steel plate and having an arc shape with a 2/3 circle cross section. . However, the first upstream main trough 815, the second upstream main trough 816, and the downstream main trough 82 may be formed integrally with the bottom plane 71 from concrete. The first upstream main trough 815, the second upstream main trough 816, and the downstream main trough 82 are arranged horizontally over the entire length in the longitudinal direction from near the end of the settling basin to the part connected to the sand collection pit 6. ing.

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 first upstream main trough 815 and the second upstream main trough 816 both have a total length of 10 m and have the same shape. 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 having a trough first discharge port 831a is provided at the upstream end portion of the upstream first main trough 815 (the tip portion of the upstream first main trough 815). Further, an upstream trough second nozzle 832 having a trough second discharge port 832a is provided at the upstream end portion of the upstream second main trough 816 (the tip portion of the upstream second main trough 816). The first trough outlet 831a and the second trough outlet 832a correspond to an example of a first outlet. The first cover member 13 is arranged inside the first main trough 815 on the upstream side. Further, the second cover member 14 is arranged inside the upstream second main trough 816. The first cover member 13 and the second cover member 14 extend along the upstream first main trough 815 and the upstream second main trough 816, respectively. The total length of the first cover member 13 and the second cover member 14 is approximately the same as the total length of the upstream first main trough 815 and the upstream second main trough 816. As shown in FIG. 2, the first cover member 13 extends from upstream of the trough first discharge port 831a to just a little downstream beyond the part of the upstream first main trough 815 connected to the sand collection pit 6. There is. The sand accumulated in the first upstream main trough 815 is moved to the sand collection pit 6 by discharging fluid from the trough first discharge port 831a with wastewater accumulated in the first upstream main trough 815. I can do it. Further, the second cover member 14 extends from upstream of the trough second discharge port 832a to just a little downstream beyond the part of the upstream second main trough 816 connected to the sand collection pit 6. The sand accumulated in the upstream second main trough 816 is moved to the sand collection pit 6 by discharging fluid from the trough second discharge port 832a with waste water accumulated in the upstream second main trough 816. I can do it. A detailed explanation of the movement of sand within the first upstream main trough 815 and the second upstream main trough 816, as well as the first cover member 13 and the second cover member 14 will be described later.

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 total length of the downstream main trough 82 is 5 m. The upstream end of the downstream main trough 82 is connected to the sand collection pit 6. A downstream trough nozzle 84 having a third trough discharge port 84a is provided at the downstream end of the downstream main trough 82 (the tip portion of the downstream main trough 82). This trough third outlet 84a also corresponds to an example of the first outlet. The third cover member 15 is arranged inside the downstream main trough 82 . This third cover member 15 extends along the downstream main trough 82. The total length of the third cover member 15 is approximately the same as the total length of the downstream main trough 82. As shown in FIG. 2, the third cover member 15 extends from downstream of the third trough discharge port 84a to just a little upstream beyond the part of the downstream main trough 82 connected to the sand collection pit 6. ing. With wastewater accumulated in the downstream main trough 82, the sand accumulated in the downstream main trough 82 can be moved to the sand collection pit 6 by discharging fluid from the trough third discharge port 84a. A detailed explanation of the movement of sand within the downstream main trough 82 and the third cover member 15 will be given later.

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. In FIG. 3, the dust remover is not shown.

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.

4(a) is an enlarged view showing the Z section of FIG. 3, and FIG. 4(b) is a schematic perspective view showing the first cover member and the first upstream trough nozzle. In FIG. 4(a), the horizontal direction of the figure is the width direction of the pond, and the direction perpendicular to the page is the longitudinal direction. Further, in FIG. 4(a), hatching representing the cross section of the upstream first main trough and the first cover member is omitted.

FIG. 4A shows the upstream first main trough 815, the upstream trough first nozzle 831, and the first cover member 13. The upstream second main trough 816, the upstream trough second nozzle 832, and the second cover member 14, as well as the downstream main trough 82, the downstream trough nozzle 84, and the third cover member 15 are connected to the bottom plane 71. Alternatively, since they have the same shape except for the connection surface 73, the explanation will be omitted. As described above, the upstream first main trough 815 of this embodiment has a 2/3 circular cross-sectional shape. That is, it has a circular arc shape with its center point being the trough arc center 815c, which is the center in the radial direction. However, the cross-sectional shape of the upstream first main trough 815 is not limited to an arc shape, but may be U-shaped, V-shaped, or the like. The first upstream main trough 815 is shaped like a cylindrical body with an inner diameter of 300 mm with the upper part cut out, and is open upward over its entire length. Hereinafter, this open portion may be referred to as a first trough opening 815b. The small trough 72 is connected to the first trough opening 815b, and the position of the first trough opening 815b in the height direction is the same as the position of the lower end of the small trough 72 in the height direction. The upper portion 815a of the upstream first main trough 815 above the trough arc center 815c has a width in the pond width direction that becomes narrower toward the first trough opening 815b at the upper end. Thereby, even if sand is blown up within the first main trough 815 on the upstream side, the upper portion 815a acts as a barb, and the sand that has been blown up can be returned into the first main trough 815 on the upstream side.

The first cover member 13 has a 5/6 circular cross-sectional shape with an opening 13a at its lower end. That is, it has an arc shape with the center point of the covering arc center 13c being the center in the radial direction. The first cover member 13 is made of a stainless steel plate with a thickness of 3 mm and is formed into an arcuate cross-section with an inner diameter of 150 mm. The opening 13a is provided over the entire length of the first cover member 13. The first cover member 13 partitions the internal space of the first main trough 815 on the upstream side. The space inside the first cover member 13 becomes a transport space FS, which is a space covered by the first cover member 13. Since the first cover member 13 has an arcuate shape with a closed upper part, the sand that has settled in the settling basin 2 toward the upper part of the first cover member 13 is removed from the upper part of the first cover member 13. easy to slide over the outer surface of the The sand that has slipped is deposited below the first main trough 815 on the upstream side. Further, the conveyance space FS below the cover arc center 13c of the first cover member 13 becomes narrower in the width direction toward the lower opening 13a. The first cover member 13 is supported by a support fitting 131 (see FIG. 5) fixed to concrete cast on the bottom of the sand settling basin 2 with a chemical anchor (registered trademark). The height position of the upper end of the first cover member 13 is located at approximately the same height as the first trough opening 815b. It is desirable that the height position of the upper end of the first cover member 13 be approximately the same height as the first trough opening 815b or a position lower than the first trough opening 815b. With this position, if the upstream first main trough 815 is filled with water, the inside of the first cover member 13 can be filled with water. By filling the inside of the first cover member 13 with water when the fluid is discharged into the water from the trough first discharge port 831a, a strong flow of fluid can be created inside the first cover member 13. Further, the opening 13a of the first cover member 13 is arranged below the center 815h of the upstream first main trough 815 in the height direction. With this arrangement, the opening 13a of the first cover member 13 and the sand deposited below the upstream side first main trough 815 can be brought closer together, so that the upstream side The sand accumulated in the first main trough 815 can be easily sucked up into the first cover member 13. Note that since both ends of the first cover member 13 in the extending direction are open, if the water level of the settling basin 2 is higher than the upper end position of the first cover member 13, air will not remain in the conveyance space FS. Therefore, the transport space FS is filled with dirty water. Further, the first cover member 13 of the present embodiment has an arc-shaped cross section, but it may also have a polygonal cross-section, or one in which a circular arc and a linear portion are continuous. It may be. However, it is desirable that the cross-sectional shape of the upper portion of the first cover member 13 be an inclined surface that is inclined downward in the width direction of the groove. By making the upper part of the first cover member 13 an inclined surface, the sand that has settled in the upper part of the first cover member 13 can easily slide down the upper part, so that the sand inside the first main trough 815 on the upstream side can easily slide down the upper part. It tends to accumulate downward.

The trough first discharge port 831a is arranged within the conveyance space FS within the first cover member 13. The trough first discharge port 831a is in the shape of a long hole made by flattening the tip of a pipe with an inner diameter of 80 mm from above and below. The maximum opening length of the trough first discharge port 831a in the pond width direction is 117 mm, and the maximum height in the vertical direction is 18 mm. The trough first discharge port 831a may have another shape such as a perfect circle. However, by making the trough first discharge port 831a flat, the fluid can be discharged over a wider range than if it were a perfect circle before being crushed. The discharge flow rate of the fluid discharged from the trough first discharge port 831a is preferably 8 m/sec or more. If it is less than 8 m/sec, the flow velocity may be insufficient and the sand may not be moved a predetermined distance. Further, it is desirable that the discharge pressure of the fluid discharged from the trough first discharge port 831a is 0.05 MPa or more and 0.3 MPa or less. The center of the trough first outlet 831a coincides with the covering arc center 13c. The trough first discharge port 831a discharges fluid in the longitudinal direction that is the extending direction of the first cover member 13. As shown in FIG. 4(b), the first cover member 13 extends in the fluid discharge direction so as to cover the trough first discharge port 831a and the fluid discharged from the trough first discharge port 831a. ing. An axis extending in the flow direction of the fluid discharged from the trough first discharge port 831a starting from the center of the trough first discharge port 831a (covering arc center 13c) becomes the virtual axis VL. That is, the first cover member 13 extends so as to cover the virtual axis VL extending in the longitudinal direction from the center of the trough first discharge port 831a. The extending direction of the first cover member 13 and the discharge direction of the fluid discharged from the trough first discharge port 831a do not need to completely match the longitudinal direction, but by making them coincide, sand is conveyed more efficiently. can. Note that even if the discharge direction of the fluid discharged from the trough first discharge port 831a and the extending direction of the first cover member 13 are slightly different, the discharged fluid is guided by the first cover member. , the flow direction of the fluid coincides with the extending direction of the first cover member. Therefore, the virtual axis VL in this case becomes the extending direction of the first cover member. However, in this case, the fluid may collide with the first cover member and the flow may be weakened, so the discharge direction of the fluid discharged from the trough first discharge port 831a and the extending direction of the first cover member 13 should match. This is desirable. Further, the center of the trough first outlet 831a may be located at a different position from the covering arc center 13c, for example, it may be located below the covering arc center 13c and above the opening 13a. However, by aligning the center of the trough first outlet 831a with the covering arc center 13c, it is possible to minimize the loss of the flow of the fluid discharged from the trough first outlet 831a. On the other hand, by arranging the center of the trough first discharge port 831a below the cover arc center 13c, it is possible to increase the suction force for sucking sand into the conveyance space FS from the opening 13a. Therefore, it is desirable that the center of the trough first outlet 831a be located between the cover arc center 13c and the opening 13a of the first cover member 13.

By discharging the fluid into the conveyance space FS from the trough first discharge port 831a, a fluid flow is generated in the conveyance space FS inside the first cover member 13. A pressure difference is generated between the transfer space FS and the outside of the first cover member 13 due to the fluid flow. That is, negative pressure is generated in the transfer space FS where fluid flow is occurring. The sand accumulated in the first upstream main trough 815 is sucked into the conveyance space FS from the opening 13a by negative pressure, as indicated by the curved arrow shown in FIG. 4(a). Further, the fluid discharged from the trough first discharge port 831a is prevented from spreading in the radial direction perpendicular to the longitudinal direction by the first cover member 13, so that the flow is maintained within the conveyance space FS over a long distance. The sucked sand is transported toward the sand collection pit 6 side by the flow of fluid generated within the transport space FS. In this embodiment, by forming the transport space FS with the first cover member 13, it can be utilized for transporting sand without impairing the flow of the fluid discharged from the trough first discharge port 831a. As a result, the sand accumulated in the upstream first main trough 815 can be efficiently transported toward the sand collection pit 6. As described above, the area below the covering arc center 13c in the conveyance space FS becomes narrower in the width direction toward the lower opening 13a. By forming the width of the opening 13a narrow in the pond width direction, sand being transported within the transport space FS is less likely to leak out from the transport space FS. Further, since the fluid in the transport space FS is difficult to flow out of the transport space FS, the flow of the fluid can be maintained over a long distance, and the sand can be moved further. Then, it becomes easier to maintain the negative pressure in the conveyance space FS even at a position away from the trough first discharge port 831a.

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 between the right side wall Wb and the protruding wall 10, respectively. 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. 5 is a sectional view taken along line AA of the sand settling basin shown in FIG. In FIG. 5, the pillars 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 5. It is located at a medium height.

As shown in FIG. 5, 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. 5 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 on the upstream side of the bottom plane 71 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 plane 71 and the upstream portion of the main trough 8. That is, the endless chain 51 and the upper portion of the filter screen 53 overlap the bottom plane 71 and the main trough 8 in the longitudinal direction. Note that FIG. 5 also shows a support fitting 151 that supports the third cover member 15.

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. 5, the sand collecting 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 collecting 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).

As shown in FIG. 5, one end of a sand pump 64 is connected to the sand pump 61. Further, the other end of the sand pumping pipe 64 is connected to a conveying pipe 66 above the sand settling basin 2 . The sand pumping pipe 64 is a pipe that connects the sand pumping pump 61 and the conveying pipe 66. Further, the conveying pipe 66 is a pipe extending above the sand settling basin 2 in a substantially horizontal direction. A check valve 641 and a gate valve 642 are installed in the sand pumping pipe 64. The conveyance pipe 66 is supported by a suspension stand 67 provided on the ground and extends in the pond width direction. The sand pumping pipe 64 and the conveying pipe 66 will be described in detail later. The sand pump 61, the sand pump 64, and the transport pipe 66 correspond to an example of sand transport equipment.

FIG. 6 is an enlarged view of section B in FIG. 5. FIG. In FIG. 6, the flow direction of wastewater is shown by a straight arrow. Also shown in FIG. 6 are side walls. Further, although FIG. 6 shows one of the six nozzle headers, the other five nozzle headers also have the same configuration as the nozzle header shown in FIG. 6.

As shown in FIG. 6, 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 . This outlet 911 corresponds to an example of a second outlet. Among the 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 one side discharge ports, and the discharge ports 911 provided in the first nozzle header 9a (see FIG. The discharge port 911 provided in the nozzle header 9e (see FIG. 2) corresponds to an example of the other side discharge port. The fluid is discharged from the discharge port 911 into the atmosphere while the water level of the sand settling basin 2 is lowered below a predetermined value to expose the sand deposited on the bottom plane 71 and the small trough 72 and the discharge port 911 to the atmosphere. By doing so, the sand accumulated on the bottom plane 71 and the small trough 72 shown in FIGS. 2 and 5 can be flowed into the main trough 8. The discharge pressure of the fluid injected from one discharge port 911 is, for example, 0.005 MPa, preferably 0.0002 MPa or more and 0.005 MPa or less. That is, the discharge pressure of the fluid discharged from the discharge port 911 is lower than the discharge pressure (0.05 MPa or more and 0.3 MPa or less) of the fluid discharged from the trough first discharge port 831a. By doing this, while securing a flow rate that allows the sand accumulated on the bottom plane 71 and the small trough 72 to flow into the main trough 8, an inexpensive and small-sized water pump 33 for supplying fluid can be used. can.

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. 6, 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. 7(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. 7(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. 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. 7, 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. 7(a) and 7(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 relative to the branch pipe 932, as shown in the supply pipe 92 shown in FIG. 7(b). That is, in this embodiment, since the main pipe 93 (see FIG. 5) 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 instead of the lap joint 934, the supply pipe 92 can be connected to the main pipe 93 so as to be able to rotate continuously.

Further, as shown in FIG. 6, 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. 8(a) is a sectional view taken along line CC in FIG. The side walls and bottom plane are also shown in FIG. 8(a).

As described above, the left side wall Wa has a convex wall portion Wa1 and a recessed wall portion Wa2. In FIG. 8A, 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. 8A, the fluid is discharged in a direction toward the center in the pond width direction rather than a direction directly below from the center of the supply pipe 92 (vertical direction). In this discharge port 911, the angle θ1 at which the fluid is discharged with respect to the bottom plane 71 is approximately 50 degrees. By setting the angle θ1 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 θ1 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. 8(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 collection nozzle 91 can be changed freely. In FIG. 8A, 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 collection 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. 8(b) is a cross-sectional view similar to FIG. 8(a) for explaining the change in the discharge direction by the sand collection nozzle. The side walls and bottom plane are also shown in FIG. 8(b).

As shown in FIG. 8(b), 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. 9 is a schematic cross-sectional view of four sewage treatment facilities cut in the pond width direction at the sand collection pit portion and viewed in the longitudinal direction. In FIG. 9, the sand collecting pit, the sand pumping pipe, and the conveying pipe are shown, and the background is omitted. Moreover, FIG. 10 is a skeleton diagram showing a sand pump, a sand pump, a conveying pipe, and a sand separator.

As mentioned above, four of the sewage treatment facilities 1 described so far are provided in parallel with respect to the flow direction of sewage. Therefore, as shown in FIG. 9, four settling basins 2 are also provided side by side in the basin width direction. The sand pump 61 and the sand pump 64 are provided in the sand settling basin 2, respectively. The sand pumping pipe 64 extends from the bottom of the settling basin 2 to above the settling basin 2. The conveying pipe 66 is supported by a suspension stand 67, and extends in a straight line almost horizontally so as to straddle above the three settling basins 2 on the right side in FIG. That is, the conveying pipe 66 extends in a direction intersecting with the sand pumping pipe 64. Note that the conveyance pipe 66 may extend in a direction inclined with respect to the horizontal direction. One end 66a of the conveyance pipe 66 is constituted by a lid that closes the conveyance pipe 66 and is disposed above the left side wall Wa of the leftmost sand settling basin 2 in FIG. Moreover, as shown in FIG. 10, the other end of the conveyance pipe 66 is connected to a sand settling separator SS placed on the ground apart from the sand settling basin 2. The sand that has passed upward through the sand lifting pipe 64 is fed into the transport pipe 66, and is transported within the transport pipe 66 from the left side to the right side in FIG.

11(a) is an enlarged view showing section E in FIG. 9, and FIG. 11(b) is an enlarged view of FIG. 11(a) viewed from the upstream side of the transport pipe in the transport direction. In FIG. 11(a), the left-right direction is the pond width direction, and the direction perpendicular to the page is the longitudinal direction of the settling basin. In addition, in FIG. 11(b), the left-right direction of the figure is the longitudinal direction of the settling basin, and the direction perpendicular to the page is the width direction of the basin. Note that the suspension stand is not shown in FIG. 11.

As shown in FIGS. 11(a) and 11(b), the sand pumping pipe 64 has a main sand pumping section 64a that extends from the sand pump 61 to the upper side beyond the conveying pipe 66, and a central axis of the pipe that extends horizontally. It has a horizontal part 64b facing toward the direction of the pipe, an inclined part 64c in which the central axis of the tube is inclined in the vertical direction with respect to the horizontal direction, and a first elbow 64e and a second elbow 64f. The first elbow 64e and the second elbow 64f are the same L-shaped parts bent at 90 degrees. Here, since elbows bent at 90 degrees are distributed on the market as general-purpose parts, the sand pumping pipe 64 can be constructed at a low cost by employing elbows bent at 90 degrees. A check valve 641 and a gate valve 642 are provided in the main sand pumping section 64a. When the sand pump 61 (see FIG. 9) is being driven, the check valve 641 is automatically opened by the flow of sand and wastewater being pumped up by the sand pump 61, and the sand pump 61 is stopped. This valve is automatically closed by the flow of wastewater that attempts to return to the sand pump 61 side. A gate valve 642 is arranged above the check valve 641. This gate valve 642 is a valve that can manually control the flow of sand and wastewater in the main sand pumping section 64a. This gate valve 642 is normally in an open state, allowing the flow of sand and wastewater. When removing the check valve 641 for inspection of the sand settling basin 2, etc., the gate valve 642 is switched to the closed state to stop the flow of sand and sewage, thereby preventing the sewage above the gate valve 642 from flowing backwards. can.

As shown in FIG. 9, one end of the main sand pumping section 64a is connected to the sand pump 61. The main sand lifting section 64a has a portion extending in the horizontal direction, a portion extending in the vertical direction, and a portion inclined with respect to the vertical direction. However, the main sand lifting section 64a may be entirely inclined with respect to the vertical direction, or may extend entirely in the vertical direction. The check valve 641 and the gate valve 642 are arranged at the other end side portion of the main sand pumping section 64a. As shown in FIGS. 11A and 11B, the other end of the main sand pumping section 64a extends in the vertical direction from the check valve 641. The first elbow 64e is integrated with the main sand lifting section 64a by welding to the other end of the main sand lifting section 64a. The first elbow 64e and the horizontal portion 64b are connected by a flange joint. The second elbow 64f is integrated with the horizontal portion 64b by being welded to the horizontal portion 64b. The second elbow 64f and the inclined portion 64c are connected by a flange joint. As shown in FIG. 11(a), the inclined portion 64c is connected to the upper portion of the conveying pipe 66 by welding while being inclined upward from the horizontal at an angle of θ2. The upper portion of the conveyance tube 66 here refers to the portion above the central axis 66c of the conveyance tube 66. The opening formed in the portion of the conveying pipe 66 to which the sand lifting pipe 64 is connected becomes a pipe connecting portion 66b. This pipe connection portion 66b corresponds to an example of a connection portion of the conveyance pipe 66 with the sand lifting pipe 64. The horizontal portion 64b is connected to the first elbow 64e by adjusting the angle around the central axis of the horizontal portion 64b so that the central axis of the flange portion 64f1 of the second elbow 64f coincides with θ2.

Sand and wastewater sucked up by the sand pump 61 (see FIG. 9) are sent into the conveying pipe 66 via the sand pump 64. The sand and wastewater sent into the transport pipe 66 are transported in the direction of arrow G shown in FIG. 11(a). When the sand pump 61 is stopped, the check valve 641 is closed, and the sand located above the check valve 641 in the main sand pumping section 64a falls and accumulates on the check valve 641. However, since the volume inside the pipe of the main sand pumping section 64a above the check valve 641 is minute, there is very little sand within the pipe. Therefore, even if the sand accumulates on the check valve 641, it hardly affects the opening and closing of the check valve 641. On the other hand, since the pipe connecting portion 66b between the sand lifting pipe 64 (sloped portion 64c) and the transporting pipe 66 is located in the upper part of the transporting pipe 66, the sand in the transporting pipe 66 is difficult to enter into the sand transporting pipe 64. This is because the sand in the transport pipe 66 is difficult to move to the upper part of the transport pipe 66 due to its own weight. Furthermore, even if the sand in the conveying pipe 66 should enter the sand pumping pipe 64, the horizontal part 64b etc. are arranged above the pipe connecting part 66b, so that the sand will fall into the slope part 64c. There is no way to climb up to reach the horizontal part 64b. That is, since the sand is dammed up by the inclined portion 64c, it is possible to prevent sand that has entered the sand pumping pipe 64 from the conveying pipe 66 from being deposited on the check valve 641. Therefore, it is possible to reliably prevent a large amount of sand from accumulating on the check valve 641 and making it impossible to open the check valve 641. In this embodiment, an example has been shown in which the horizontal portion 64b and the like are arranged above the pipe connecting portion 66b. However, if there is a portion of the sand lifting pipe 64 located above the pipe connecting portion 66b between the check valve 641 and the conveying pipe 66, the above-mentioned effect of damming up sand can be obtained. Hereinafter, the portion disposed above this may be referred to as an upper disposed portion. The term "arranged above" as used herein means that the lowermost part of the internal space of the sand pumping pipe 64 in the upper part is located at a higher position than the lowermost part in the pipe connecting part 66b. However, it is more desirable that the entire internal space of the sand pumping pipe 64 in the upper portion is located above the top of the pipe connecting portion 66b. According to this aspect, the effect of damming up sand becomes more reliable.

In this embodiment, the angle θ2 formed by the conveying pipe 66 and the inclined portion 64c is 45 degrees. By setting θ2 to be greater than 0 degrees and less than 90 degrees, the sand lifting pipe 64 (slanted portion 64c) can be connected to the conveying pipe 66 while gradually approaching the conveying pipe 66 in the conveying direction of the conveying pipe 66. can. This has the effect of suppressing the sand that has been sucked up in other sand settling basins 2 and is being transported inside the transport pipe 66 from the side opposite to the transport direction of the pipe connection portion 66b from entering into this sand pumping pipe 64. be. Furthermore, the sand moving from inside the sand pumping pipe 64 into the transporting pipe 66 is fed into the transporting pipe 66 in a direction close to the transporting direction, and is carried as it is along with the flow of sewage generated inside the transporting pipe 66. Since it moves in the direction, it also has the effect of preventing it from returning into the sand pumping pipe 64. These effects can prevent a large amount of sand from accumulating on the check valve 641 and making it impossible to open the check valve 641. In addition, since the wastewater in the sand pumping pipe 64 is sent into the transport pipe 66 in a direction close to the transport direction of the transport pipe 66, the flow of the wastewater in the transport pipe 66 in the transport direction is promoted by the sent wastewater. It also has the effect of being able to do things. However, θ2 is preferably 30 degrees or more and 60 degrees or less. If the angle is less than 30 degrees, it becomes difficult to connect the sand pumping pipe 64 and the conveying pipe 66. Moreover, if the angle exceeds 60 degrees, the above-mentioned effect will be halved.

FIG. 12 is a water supply system diagram in a sewage treatment facility.

As shown in FIG. 12, 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. 13 is an explanatory diagram showing the water level of the settling basin and the water level sensor.

As shown in FIG. 13, a water level sensor 99 is arranged in the sand collection pit 6 of the sand settling basin 2. This water level sensor 99 is located at a first high water level HHWL where the water level of the sand settling basin 2 is above the bottom plane 71, and at an upper end position 13b (main position) of each cover member 13, 14, 15 below the first high water level HHWL. The second high water level THWL is located above the upper end 8b of the trough 8, that is, the opening of the main trough 8, and the lower end 72b of the small trough 72. , 15, the first intermediate water level TMWL between the second high water level THWL and the first low water level TLWL, and the main water level below the upper end 8b of the main trough 8. A third high water level HWL above the lower end 8a of the trough 8, a second low water level LWL below the sand collection pit 6, and a second high water level HWL between the third high water level HWL and the second low water level LWL. It detects and outputs the interlock water level LLWL, which is lower than the intermediate water level MWL and the second low water level LWL.

FIG. 14 is a flowchart showing the flow of sand removal operations in a sewage treatment facility.

The operation of the sewage treatment facility 1 having the above-described configuration will be explained with reference to FIGS. 1, 2, 14, 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. When a predetermined time is reached, the sand removal operation is performed for all four sewage treatment facilities 1 one by one in turn. This predetermined period may be regular, such as once a month, or may be when the total flow rate of the wastewater flowing into or discharged from the settling basin 2 reaches a certain amount. In the sand removal operation, first, the inlet gate 42 of the dam device 4 shown in FIG. 1 is driven to close the inlet 411, thereby damming the inflow of wastewater into the settling basin 2 (step S1). 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 water pump 31 is stopped (step S2). 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. At this time, conventionally, the sand that had accumulated on the check valve 641 for a long period of time between the previous sand removal operation and the current sand removal operation solidified and became almost solid, and the check valve 641 Sometimes it became impossible to open. However, in this embodiment, only a very small amount of sand accumulates on the check valve 641, so the check valve 641 does not become unable to open. When the water level in the sand settling basin 2 falls to the second high water level THWL (see FIG. 13), the water supply pump 33 is driven again to discharge fluid from the stirring nozzle 62 shown in FIG. 2. Then, the driving of the sand pump 61 is set to operation mode A described below (step S3). The sand pump 61 operates in either operation mode A or operation mode B. In operation mode A, the drive is stopped in response to the output from the water level sensor 99 indicating the first low water level TLWL (see FIG. 13), and the drive is resumed in response to the output indicating the second high water level THWL (see FIG. 13). control will be executed automatically. This operation mode A is a mode in which the water level is maintained above the upper end position 13b of each cover member 13, 14, 15. Therefore, in operation mode A, each cover member 13, 14, 15, the first trough outlet 831a, the second trough outlet 832a, and the third trough outlet 84a are submerged in water. In operation mode B, the driving of the sand pump 61 is stopped in response to the output from the water level sensor 99 indicating the second low water level LWL (see FIG. 13), and the drive of the sand pump 61 is stopped in response to the output indicating the third high water level HWL (see FIG. 13). Control is automatically executed to restart the drive accordingly. This operation mode B is a mode in which the water level is maintained below the lower end 72b of the small trough 72. Therefore, the bottom plane 71, the small trough 72, the sand deposited thereon, and the sand collecting means 9 are exposed to the atmosphere. 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 conveyed to the sand collection pit 6 is transported by the sand pump 61 to the sand separator SS (see FIG. 10) outside the sand settling basin 2 while the sand pump 61 is operating. The sand pump 61 repeats driving and stopping even during this sand removal operation. In this embodiment, since a large amount of sand does not accumulate on the check valve 641 during the stoppage, the check valve 641 will not become unable to open when the drive is resumed. 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 13), it is considered that some kind of 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 (step S4). In addition, in this step S4, after the fluid is discharged from one of the upstream trough first nozzle 831 and the upstream trough second nozzle 832 for a certain period of time, the fluid may be discharged from the other for a certain period of time. When the discharge of fluid from the stirring nozzle 62, the first upstream trough nozzle 831, and the second upstream trough nozzle 832 stops, the sand pump 61 is switched to operation mode B (step S5). Then, when it is detected that the water level is below the third high water level HWL, fluid is discharged from the discharge port 911 (see FIG. 6) provided in the fifth nozzle header 9e. By this discharge, the sand accumulated on the bottom plane 71 and the small trough 72 between the right side wall Wb near where the fifth nozzle header 9e is arranged and the upstream second main trough 816 is removed from the upstream second main trough. 816. After a predetermined period of time has elapsed to allow the sand to flow sufficiently, the sand pump 61 is switched to operation mode A while continuing fluid discharge from the discharge port 911 provided in the fifth nozzle header 9e. After that, when it is detected that the water level is equal to or higher than the first intermediate water level TMWL, the discharge of fluid from the discharge port 911 provided in the fifth nozzle header 9e is stopped (step S6). 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 (step S7). When the discharge of fluid from the stirring nozzle 62 and the upstream trough second nozzle 832 stops, the sand pump 61 is switched to operation mode B (step S8). Then, when it is detected that the water level is below the third high water level HWL, fluid is discharged from the discharge port 911 provided in the second nozzle header 9b. After a predetermined period of time has elapsed to allow the sand accumulated on the bottom plane 71 and small trough 72 between the left side wall Wa near where the second nozzle header 9b is arranged and the upstream first main trough 815 to be sufficiently washed away, The sand pump 61 is switched to operation mode A while continuing fluid discharge from the discharge port 911 provided in the two-nozzle header 9b. Thereafter, when it is detected that the water level is equal to or higher than the first intermediate water level TMWL, the discharge of fluid from the discharge port 911 provided in the second nozzle header 9b is stopped (step S9). Of these, the discharge ports 911 located near the recessed wall Wa2 and the inclined wall Wa3 are configured such that the fluid discharge direction is such that a certain amount of fluid reaches the left side wall Wa depending on the distance from the supply pipe 92 to the left side wall Wa. It has been adjusted. Therefore, all the sand accumulated on the bottom plane 71 and the small trough 72 between the left side wall Wa near where the second nozzle header 9b is arranged and the upstream first main trough 815 is removed from the upstream first main trough 815. It can flow up to 815. After stopping the discharge of the fluid from the discharge port 911 provided in the second nozzle header 9b, the fluid is discharged for a certain period of time from the stirring nozzle 62 and the upstream trough first nozzle 831, and then flows into the upstream first main trough 815. The collected sand is sent to the sand collecting pit 6 (step S10). When the discharge of fluid from the stirring nozzle 62 and the upstream trough second nozzle 832 is stopped, the sand pump 61 is switched to operation mode B (step S11). After that, similar to the operations in steps S6 to S10 described above, fluid is discharged from the discharge port 911 provided in the fourth nozzle header 9d, and after a predetermined time elapses, switching to operation mode A (step S12), stirring nozzle 62, fluid is discharged from the upstream trough second nozzle 832 (step S13), switching to operation mode B (step S14), fluid is discharged from the discharge port 911 provided in the first nozzle header 9a, and a predetermined time elapses. By switching to the later operation mode A (step S15) and discharging fluid from the stirring nozzle 62 and the first upstream trough nozzle 831 (step S16), the sand is deposited at the bottom of the pond upstream from the sand collection pit 6. All of the accumulated sand is carried out to the outside of the sand 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 collapse 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-mentioned operation, fluid is discharged for a certain period of time from the stirring nozzle 62 and the downstream trough nozzle 84 to flow the sand accumulated on the downstream main trough 82 into the sand collection pit 6 (step S17). When the discharge of fluid from the stirring nozzle 62 and the downstream trough nozzle 84 is stopped, the sand pump 61 is switched to operation mode B (step S18). Then, when it is detected that the water level is below the third high water level HWL, fluid is discharged from the discharge port 911 provided in the sixth nozzle header 9f. After a predetermined period of time has elapsed to allow the sand accumulated on the bottom plane 71 and the small trough 72 between the right side wall Wb near where the sixth nozzle header 9f is arranged and the downstream main trough 82 to be sufficiently washed away, the sixth nozzle The sand pump 61 is switched to operation mode A while continuing fluid discharge from the discharge port 911 provided in the header 9f. Thereafter, when it is detected that the water level is equal to or higher than the first intermediate water level TMWL, the fluid discharge from the discharge port 911 provided in the sixth nozzle header 9f is stopped (step S19). 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 collection pit 6 (step S20). When the discharge of fluid from the stirring nozzle 62 and the downstream main trough 82 is stopped, the sand pump 61 is switched to operation mode B (step S21). Then, similar to the operations in steps S19 and S20 described above, the fluid is discharged from the discharge port 911 provided in the third nozzle header 9c, and after a predetermined time elapses, the operation mode A is switched (step S22), and the stirring nozzle 62 By operating in this order: and discharging fluid from the downstream trough nozzle 84 (step S23), all the sand deposited on the bottom of the pond on the downstream side of the sand collection pit 6 is carried out to the outside of the sand settling basin 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 (step S24). 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. This series of sand removal operations is performed in order for each of the four sewage treatment facilities 1.

In this sand removal operation, when the sand pump 61 is switched from operation mode A to operation mode B, fluid is not supplied to the sand settling basin 2 until it is detected that the water level is below the third high water level HWL. It's stopped. Thereby, the speed at which the water level falls can be increased. At that time, in order to stop the supply of fluid to the sand settling basin 2, the supply switching valve Va shown in FIG. There is. By doing so, the supply of fluid to the sand settling basin 2 can be stopped while the water supply pump 33 continues to be driven. In the sand removal operation described above, steps S4, S7, S10, S13, S16, S17, S20, and S23 each correspond to an example of an underwater discharge process. Furthermore, each of steps S6, S9, S12, S15, S19, and S22 corresponds to an example of an atmospheric discharge process. That is, in this embodiment, the process of performing the underwater discharge process after the execution of the atmospheric discharge process is performed by a set of sand collection processes (steps S6 and S7, S9 and S10, S12 and S13, S15 and S16, S19 and S20, For each combination of S22 and S23), the sand collection process is executed multiple times. Moreover, before performing the first sand collection process (steps S6 and S7), an underwater discharge process (step S4) is executed. If sand remains in the main trough 8 during the atmospheric discharge process, the sand that was washed into the main trough 8 during the atmospheric discharge process will be piled on top of the remaining sand, resulting in a large amount of sand remaining in the main trough 8. There is a risk of sand accumulating. Furthermore, there is a risk that the main trough 8 will be filled with sand during the discharge process into the atmosphere, and the overflowing sand will remain on the bottom plane 71. In this embodiment, the sand flowed from the bottom plane 71 to the main trough 8 is transported to the sand collection pit 6 in a set of sand collection processes, so that there is no possibility that sand will remain in the main trough 8. There is no. In addition, since the underwater discharge process (steps S4 and S17) is executed before the first sand collection process (each combination of steps S6 and S7, and S19 and S20), even during the first sand collection process, No sand remains in the main trough 8.

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. Therefore, 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. In addition, when the water level sensor 99 detects that the water level has decreased to the first intermediate water level TMWL in operation mode A and the second intermediate water level MWL in operation mode B, in addition to the nozzle that is discharging fluid at that point, other nozzles Additional fluid may be discharged from the. 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 to reach the first low water level TLWL or the second 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 fluid from the nozzle header that is scheduled to be discharged next, the sand in the bottom plane 71 and small trough 72 that are to be discharged next can be preliminarily flushed out, so that the residual sand can be further suppressed. can. Moreover, the fluid to be additionally discharged may be fluid stored in other equipment. Furthermore, even if the first low water level TLWL or the second low water level LWL is reached, the sand pump 61 is not stopped, and instead of stopping, in addition to the fluid pumped by the water supply pump 33, the fluid stored in other equipment is It may be configured to be supplied to the sand settling basin 2. 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 THWL or the third 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 water flows down.

FIG. 15 is a cross-sectional view of the sand settling basin similar to FIG. 5, 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 FIG. 15, the sand collecting means arranged in the upper part of the sand settling basin is indicated by a chain double-dashed line. Furthermore, 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. 15 , a virtual upper nozzle header 90 is shown in the upper part of the grit settling basin 2 . This upper nozzle header 90 is used instead of the first nozzle header 9a. 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 basin 2 is located on the downstream side compared to the case where it is arranged near the bottom of the sand settling basin 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 mentioned above, the upper portions of the endless chain 51 and the filter screen 53 that constitute the dust remover 5 overlap the bottom plane 71 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 placed upstream by a distance S from the positions shown in FIGS. 5 and 15, 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 14 will be mainly explained, and components having the same names as those in the embodiment shown in FIGS. 1 to 14 will be described. will be explained using the reference numerals used so far, and redundant explanations will be omitted.

FIG. 16 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. 16, the first connection surface 732 and the second connection surface 733 have a cross-sectional shape of 1/4 circle. 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 semi-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.

17(a) is a diagram showing a first modification of the supply pipe and sand collection nozzle shown in FIG. 8, and FIG. 17(b) is a diagram showing a second modification of the supply pipe and sand collection nozzle shown in FIG. FIG.

In this first modification, a lap joint 934 is not arranged on 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 on the sand collecting nozzle 91. This point differs from the example shown in FIG. 8(a). In FIG. 17A, 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 collecting 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 installed in the circumferential direction of the supply pipe 92. This example differs from the example shown in FIG. 8A in that a plurality of portions 924 are formed. In FIG. 17(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.

Next, modifications of the main trough 8, each cover member 13, 14, 15, and the bottom plane 71 will be described.

FIG. 18 is a cross-sectional view similar to FIG. 5 showing a modification of the main trough, cover member, and bottom plane.

This modified example differs from the example shown in FIG. 5 in that the main trough 8, each cover member 13, 14, 15, and bottom plane 71 are arranged to be inclined downward toward the sand collection pit 6. . In addition, in FIG. 18, in order to show an inclination clearly, the inclination of the main trough 8, each cover member 13,14,15, and the bottom plane 71 is shown exaggeratedly. As shown in FIG. 18, the bottom plane 71 is inclined downward by about 0.5 degrees in the longitudinal direction so that the end on the side of the sand collecting pit 6 is the deepest. In addition, the first upstream main trough 815 and the downstream main trough 82 are also inclined downward by about 0.5 degrees as they go toward the sand collection pit 6, similar to the bottom plane 71, and are connected to the sand collection pit 6. The part is the deepest. Furthermore, the first cover member 13 and the third cover member 15 are also inclined downward by about 0.5 degrees toward the sand collection pit 6, and the portion connected to the sand collection pit 6 is the deepest. Note that the upstream first main trough 815 and the second cover member 14, which are not shown in FIG. In this modification, by providing each cover member 13, 14, 15, not only the conveying force of sand in the main trough 8 is increased, but also by making the main trough 8 and each cover member 13, 14, 15 incline. The flow of fluid discharged into each covering member 13, 14, 15 is assisted. Thereby, the sand accumulated in the main trough 8 can be transported over a longer distance. Note that the inclination angle may be appropriately set according to the length of the main trough 8.

FIG. 19 is a sectional view similar to FIG. 8(a) showing the bottom plane near the upstream end of the sand settling basin and the bottom plane near the sand collection pit in the modified example shown in FIG. 18. Also shown in FIG. 19 are the side walls and bottom plane.

FIG. 19 shows the height direction of the bottom plane 71 when the bottom plane 71 is inclined downward toward the sand collecting pit 6 side so that the edge on the sand collecting pit 6 side is the deepest. shows the difference in position. In FIG. 19, 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 collecting pit 6 is shown by a chain double-dashed line. As shown in FIG. 19, in this case, 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. 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 collection 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. In particular, 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 height of the bottom plane 71 (distance from the supply pipe 92 to the bottom plane 71). can be discharged.

Next, a modification example in which the height of the main trough 8 is increased will be described.

FIG. 20 is an explanatory diagram similar to FIG. 13 showing an example of water level detection when the height of the main trough is increased.

In the example shown in FIG. 13, each cover member 13, 14, 15 was formed to have a height exceeding half of the height of the main trough 8. The upper end position 13b of each cover member 13, 14, 15 was approximately the same position as the lower end 72b of the small trough 72 (the upper end 8b of the main trough 8). As described above, the operation mode A of the sand pump 61 is a control mode in which each cover member 13, 14, 15 is maintained in a submerged state, so that the upper end position 13b of each cover member 13, 14, 15 is It is necessary to set the first low water level TLWL above . In addition, the operation mode B of the sand pump 61 is a control mode in which the water level is maintained below the lower end 72b of the small trough 72. 3. It is necessary to set the high water level HWL. In the example shown in FIG. 13, in order to satisfy the conditions that the first low water level TLWL is set above the upper end position 13b and the third high water level HWL is set below the lower end position 72b, the first low water level TLWL is lower than the first low water level TLWL. There is no choice but to set the third high water level HWL below this level. As a result, there is no overlap between the water level maintenance ranges in operation mode A and operation mode B, and when switching from one mode to the other mode, there is no waiting time until the water level falls within the range of the other mode. was. As shown in FIG. 20, when the height of the main trough 8 is increased and each cover member 13, 14, 15 is arranged at the lower part of the main trough 8, the upper end position of each cover member 13, 14, 15 is 13b is located below the lower end 72b of the small trough 72. Therefore, even if the above conditions are met, the third high water level HWL can be set above the first low water level TLWL. That is, since a part of the water level range D1 in operation mode A and a part of the water level range D2 in operation mode B can be overlapped, the waiting time after mode switching can be eliminated or reduced.

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. Further, in this embodiment, after the sand accumulated on the bottom plane 71 and the small trough 72 on the upstream side of the sand collection pit 6 is poured out, the sand is deposited on the bottom plane 71 and the small trough 72 on the downstream side of the sand collection pit 6. Although the sand accumulated on the bottom plane 71 and the small trough 72 on the downstream side may be poured first. 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. In addition, in this embodiment, one discharge port for discharging fluid into the conveyance space FS is provided at the end (tip portion) of the main trough 8 on the opposite side from the sand collection pit 6, but each cover member A nozzle having a discharge port may be additionally provided at an intermediate position in the extending direction of 13, 14, 15. In particular, when the length of each cover member 13, 14, 15 in the extending direction is long or when the fluid discharge pressure is low, it is desirable to add a nozzle at an intermediate position or the like. Further, in this embodiment, the fluid was discharged into the transfer space FS with each cover member 13, 14, 15 completely submerged in water, but a portion of each cover member 13, 14, 15 was partially submerged in water. If it is submerged, the fluid may be discharged while the atmosphere remains in the transfer space FS. Further, in the present embodiment, fluid was discharged in a state where the first trough discharge port 831a, the second trough discharge port 832a, or the third trough discharge port 84a was completely submerged in water, but these discharge ports 831a, 832a , 84a may be partially submerged in water and the remaining portion may be exposed to the atmosphere, and the fluid may be discharged. However, in these cases, losses occur in the flow of the discharged fluid, especially at the interface between the atmosphere and water. Therefore, in a state where each cover member 13, 14, 15, trough first outlet 831a, trough second outlet 832a, and trough third outlet 84a are completely submerged in water, those outlets 831a, 832a, 84a are completely submerged in water. It is desirable to discharge fluid from.

Further, although this embodiment has been described using an example of four sewage treatment facilities 1 provided in parallel, the number of sewage treatment facilities 1 may be one or any number. In addition, although this embodiment has been described using the so-called low-pressure sand collection method sand settling tank 2, in which sand is collected while the sewage in the sand settling tank 2 is drained, a high-pressure sand collection method is used, in which sand collection is carried out while sewage is stored. It can also be applied to ponds. Furthermore, although this embodiment has been described using as an example a check valve 641 that opens and closes as a valve for preventing backflow by the flow of fluid sucked up by the sand pump 61, an electric actuator that opens and closes the valve by the driving force of an electric actuator A valve may also be used. In addition, although the sand lifting pipe 64 is connected to the upper part of the conveying pipe 66, the sand lifting pipe 64 may be connected to the side of the conveying pipe 66, or may be connected to the lower part. Furthermore, the sand lifting pipe 64 is connected to the transporting pipe 66 while gradually approaching the transporting pipe 66 as it goes in the transporting direction of the transporting pipe 66. The sand lifting pipe 64 may be connected to the conveying pipe 66 from the orthogonal direction so as to form a shape.

According to this embodiment or its modified example, the occurrence of problems in the sand settling basin 2 can be suppressed. In addition, sand can be collected efficiently. Moreover, the sand accumulated on the bottom plane 71, the small trough 72, and the connecting surface 73 can be flushed away with a fluid without leaving any residue. 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 pond 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.

Further, many of the sand settling basins 2 have a longitudinal length of 20 meters or more. In the conventional sand settling basin 2, the main trough 8 is inclined downward by, for example, 1 degree toward the sand collection pit 6 side. Therefore, compared to the depth position where the pond end side end (tip part) of the main trough 8 is located, the sand collecting pit 6 side end (rear end part) is deeper in proportion to the length of the sand settling basin 2. placed in position. Moreover, since the bottom plane 71 is formed with the same inclination angle as the main trough 8, the bottom plane 71 is similarly arranged at a deeper position on the sand collecting pit 6 side. When the length in the longitudinal direction of the settling basin 2 is long, the part of the main trough 8 and the bottom plane 71 on the sand collection pit 6 side is located at a deeper position than when the length in the longitudinal direction of the settling basin 2 is short. It will be placed. When constructing the settling basin 2, the ground is dug to below the deepest position of the settling basin 2, and then the settling basin 2 is shaped with concrete. If the main trough 8 and the bottom plane 71 are sloped, the sand collection pit 6 will be located at a deeper position than if it is not sloped, so it will be necessary to dig deep into the ground, making digging work time-consuming. It takes. Furthermore, when forming the bottom plane 71 with concrete from the dug position, it is necessary to gradually thicken the concrete from the sand collection pit 6 side toward the edge of the settling basin in order to make the bottom plane 71 slope. , used a large amount of concrete. As a result, there was a problem in that the sand settling basin 2 became expensive. In this embodiment, since the cover members 13, 14, and 15 are provided to improve sand collection efficiency, even if the inclination angle of the main trough 8 and the bottom plane 71 is made gentle, the sand in the main trough 8 can be removed from the sand collection pit. It can be transported to 6. This inclination angle is preferably 0 degrees or more and less than 1 degree, more preferably 0 degrees or more and 0.5 degrees or less. By making the inclination angle gentle, there is no need to dig deep into the ground, and less concrete can be used, so the settling basin 2 can be created at a low cost.

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 there are a plurality of discharge ports provided in the first region, it is preferable that the direction of fluid discharge from those 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 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, the discharge direction of the fluid being 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 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;
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 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.

The first connection 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.

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.

a one-side 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 discharge port on the other side that discharges a fluid for causing the sand settled on the second bottom surface to flow from the other side wall side toward the second groove.

Two dust removers may be provided, each disposed between the one side wall and the protruding wall and between the other side wall and the protruding wall, for removing contaminants contained in the received water.

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 pond, the sand contained in the received water settles to the bottom of the pond.
a groove provided at the bottom of the pond and extending in a predetermined direction;
a first discharge port that discharges fluid in the predetermined direction in the water collected in the groove;
a bottom surface provided at the bottom of the pond and connected to the groove;
a second discharge port that discharges a fluid into the atmosphere for causing sand accumulated on the bottom surface to flow from the side wall side of the settling basin toward the groove;
A sand settling basin comprising: a cover member that covers the periphery of the virtual axis extending from the center of the first discharge port toward the predetermined direction and has an opening at a lower end portion.

In this settling basin, the opening of the cover member may be arranged below the center of the groove in the height direction.

Furthermore, the following inventive concept can be extracted from the sand collection method shown in this embodiment.

A sand collection method for collecting sand deposited at the bottom of a settling pond in which the sand contained in received water is settled at the bottom of the pond, which has a groove extending in a predetermined direction and a bottom connected to the groove. There it is,
an underwater discharge step of discharging fluid from a first discharge port in the predetermined direction in the water collected in the groove;
an atmospheric discharging step of discharging fluid for flowing sand accumulated on the bottom surface from the side wall side toward the groove into the atmosphere from a second discharge port;
The underwater discharge step is a step of discharging the fluid into a space covered by a cover member having an opening at the lower end portion and covering the periphery of the virtual axis extending from the center of the first discharge port toward the predetermined direction. A sand collection method characterized by:

The underwater discharge step is a step performed while the water level is maintained above the cover member,
The discharge step into the atmosphere may be a step performed while the water level is maintained below the bottom surface.

The process of executing the underwater discharge process after the execution of the atmospheric discharge process may be treated as a set of sand collection processes, and the sand collection process may be performed multiple times.

The underwater discharge step may be performed before performing the sand collection process a plurality of times.

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.

The embodiments of the present invention have been described above, and will be summarized below, including the problems.

When the sand removal operation is not being performed, the sand pump is stopped. Additionally, during sand removal work, the sand pump may be temporarily stopped to adjust the water level in the settling basin. When the sand pump stops, the backflow prevention valve is closed. When the sand pump stops driving and the backflow prevention valve closes, the flow of sewage in the sand pumping pipe stops, and the sand between the backflow prevention valve and the transport pipe falls and the backflow prevention valve closes. Deposits on valves. If there is only sand in the sand pumping pipe, the amount will not be large. However, the sand in the conveying pipe may further enter the sand pumping pipe, and a large amount of sand may accumulate on the backflow prevention valve. Both electric valves and check valves suffer from the problem that if too much sand accumulates on the valve, the weight of the sand makes it impossible to open the valve. That is, in the case of an electric valve, if the sand accumulated on the valve becomes heavier than the driving force of the valve by the electric actuator, the valve cannot be opened. In addition, with a check valve, if the sand accumulated on the valve becomes heavier than the power of the sand pump to pump up wastewater, the valve will not be able to open. When this problem occurs, a lot of effort is required to disassemble and clean the backflow prevention valve, or to remove the entire sand pumping pipe and remove the sand inside the sand pumping pipe. Further, if the electric actuator or the sand pump continues to be driven with the valve not opening, there is a risk that the electric actuator or the sand pump will overheat and be damaged.

Therefore, it is desired to provide sand transport equipment that is less prone to malfunctions.

The sand transport equipment is designed to prevent problems from occurring, and is installed in a sand settling pond where the sand contained in the received water settles.
A pump that sucks the settled sand,
a sand pumping pipe connected to the pump, through which sand sucked by the pump passes upward;
A conveying pipe extending in a direction intersecting the sand lifting pipe and transporting sand that has passed through the sand lifting pipe,
The sand pumping pipe is provided with a backflow prevention valve that prevents backflow from the transport pipe to the pump, and between the backflow prevention valve and the transport pipe, the sand pumping pipe in the transport pipe is provided with a backflow prevention valve that prevents backflow from the transport pipe to the pump. It is characterized by having a portion located above the connection portion with the pipe.

Here, the conveying pipe may extend across the plurality of sand settling basins, and may be connected to the sand pumping pipes arranged in each of the plurality of sand settling basins. Moreover, the said conveyance pipe may be provided above the said sand settling basin, and the said pump may be arrange|positioned at the bottom part of the said sand settling basin. Further, the sand pumping pipe may extend from the bottom of the sand settling basin toward the conveying pipe above the sand settling basin. In addition, the sand pumping pipe may have a portion extending in the vertical direction, and may also have a portion extending in the horizontal direction. In this case, the vertically extending portion and the horizontally extending portion may be connected by an L-shaped pipe.

According to this sand transport equipment, even if the sand in the conveying pipe enters the sand lifting pipe for some reason, the sand will be removed from the portion of the sand lifting pipe located above the conveying pipe. Since it is dammed in front, it is possible to prevent it from accumulating on the valve for preventing backflow. Therefore, it is possible to prevent the backflow prevention valve from being unable to open due to accumulated sand.

Further, in this sand transport facility, the sand lifting pipe may be connected to an upper portion of the conveying pipe.

According to this aspect, the sand in the conveying tube tends to collect on the lower side of the conveying tube due to its own weight and is difficult to move to the upper part, so that it is possible to suppress the sand in the conveying tube from entering the sand pumping tube. . This can more reliably prevent the sand from accumulating on the backflow prevention valve.

Furthermore, in this sand transport equipment, the connecting side portion of the sand lifting pipe to the transport pipe is inclined with respect to the transport pipe so as to gradually approach the transport pipe as it goes in the transport direction of the transport pipe. It may be arranged as follows.

By doing this, the sand being transported through the transport pipe from the upstream side of the connection between the sand transport pipe and the transport pipe will not enter the sand transport pipe unless it moves against the transport direction. , the sand is prevented from entering the sand pumping pipe. Furthermore, the sand moving from the sand pumping pipe into the transporting pipe is fed in the transporting direction and moves downstream along with the flow of wastewater in the transporting pipe, so that it does not return to the sand pumping pipe. It is suppressed from coming. Furthermore, since the sewage in the sand pumping pipe is sent into the transport pipe in the transport direction, the flow of the sewage in the transport pipe can be assisted by the sent sewage.

The sand settling pond explained above is a settling pond in which the sand contained in the received water settles to the bottom of the pond.
a groove provided at the bottom of the pond and extending in a predetermined direction;
a first discharge port that discharges fluid in the predetermined direction in the water collected in the groove;
a cover member that covers the periphery of the virtual axis extending from the center of the first discharge port toward the predetermined direction and has an opening at a lower end portion;
The cover member may be arranged such that the height position of the upper end of the cover member is lower than the height position of the opening of the groove.

Moreover, in this settling basin, the center of the first discharge port may be arranged between the center of the cover member and the opening of the cover member.

In addition, the sand settling pond explained above is a settling pond in which the sand contained in the received water settles to the bottom of the pond.
a groove provided at the bottom of the pond and extending in a predetermined direction;
a first discharge port that discharges fluid in the predetermined direction in the water collected in the groove;
a bottom surface provided at the bottom of the pond, formed between the side wall of the settling basin and the groove, and connected to the groove;
a second discharge port for discharging fluid into the atmosphere for flowing sand accumulated on the bottom surface from the side wall side toward the groove;
a cover member that covers the periphery of the virtual axis extending from the center of the first discharge port toward the predetermined direction and has an opening at a lower end portion;
The cover member is arranged such that the height position of the upper end of the cover member is below the height position of the opening of the groove,
The first discharge port may discharge the fluid while the water level is maintained above the upper end of the covering member.

In addition, this sand settling pond is equipped with a sand pump that pumps up water along with sand.
The sand pump may be configured to stop and restart driving so that the water level falls within a predetermined range while the first discharge port is discharging fluid.

By the way, a settling basin with a high ability to collect settled sand is desired.

The sand settling pond explained above is a settling pond in which the sand contained in the received water settles to the bottom of the pond.
a groove provided at the bottom of the pond and extending in a predetermined direction;
a first discharge port that discharges fluid in the predetermined direction in the water collected in the groove;
a bottom surface provided at the bottom of the pond, formed between the side wall of the settling basin and the groove, and connected to the groove;
a second discharge port for discharging fluid into the atmosphere for flowing sand accumulated on the bottom surface from the side wall side toward the groove;
a cover member that covers the periphery of the virtual axis extending from the center of the first discharge port toward the predetermined direction and has an opening at a lower end portion;
Equipped with a sand pump that pumps up water along with sand,
The cover member is arranged such that the height position of the upper end of the cover member is below the height position of the opening of the groove,
The first discharge port discharges the fluid while the water level is maintained above the upper end of the covering member,
The sand pump stops and restarts driving so that the water level falls within a first predetermined range while the first discharge port is discharging the fluid, and the second discharge port is discharging the fluid. While discharging water, the drive is stopped and the drive is restarted so that the water level falls within a second predetermined range that partially overlaps the first predetermined range.

2 Sand settling basin 61 Sand pump 64 Sand pumping pipe 64c Inclined part 66 Conveying pipe 66b Pipe connection part 641 Check valve

Claims (3)

In a settling pond, the sand contained in the received water settles to the bottom of the pond.
a groove provided at the bottom of the pond and extending in a predetermined direction;
a first discharge port that discharges fluid in the predetermined direction in the water collected in the groove;
a bottom surface provided at the bottom of the pond, formed between the side wall of the settling basin and the groove, and connected to the groove;
a second discharge port for discharging fluid into the atmosphere for flowing sand accumulated on the bottom surface from the side wall side toward the groove;
a cover member that covers the periphery of the virtual axis extending from the center of the first discharge port toward the predetermined direction and has an opening at a lower end portion;
a pump that selectively supplies fluid to the first discharge port and the second discharge port;
A sand settling basin characterized in that the second discharge port discharges fluid at a discharge pressure lower than that of the first discharge port. The first discharge port discharges fluid while the inside of the cover member is filled with water received by the settling basin,
The sand settling basin according to claim 1, wherein the second discharge port discharges the fluid after draining the water received by the sand settling basin. The first discharge port discharges the fluid at a discharge pressure of 0.05 MPa or more and 0.3 MPa or less,
The sand settling basin according to claim 1 or 2, wherein the second discharge port discharges the fluid at a discharge pressure of 0.0002 MPa or more and 0.005 MPa or less.

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