Transfer system

Abstract

To provide an inexpensive transfer system.SOLUTION: A transfer system 6 is provided in sand sedimentation 1 in which sand mixed in drainage settles and is accumulated on a bottom part 1a. The transfer system 6 includes: a tank 62 arranged upward from the bottom part 1a and stores liquid for sand collection; a first water supply pipe 63 extending from the tank 62 to the sand sedimentation 1; a discharge port 632 installed in the sand sedimentation 1; a container 71 that receives mixed liquid in which sand is mixed in drainage, into a space inside a container through an inflow port, and discharges from discharge port concentrated liquid in which density of sand with respect to drainage is high; and a storage tank 72 having the discharge port arranged inside the tank and storing the concentrated liquid obtained by the container 71. The discharge port 632 discharges the liquid for sand collection that has flowed through the first water supply pipe 63 and transfers a mixed object accumulated on the bottom part 1a. The container 71 sends liquid in the received mixed liquid, from a delivery port to the tank. An aperture area of the delivery port is equal to or greater than an aperture area of the discharge port.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a transfer system installed in a pond where contaminants entrained in a liquid settle and accumulate at the bottom. [Background technology]

[0002] Sewage treatment facilities are equipped with ponds such as grit basins and sedimentation basins. A grit basin receives wastewater, such as sewage or rainwater, settles sand contained in the wastewater, transports the sand deposited at the bottom to a sand collection pit, and removes the sand collected in the sand collection pit using a sand pump. A sedimentation basin receives wastewater from which sand has been removed in the grit basin, settles sludge contained in the received wastewater, transports the sludge deposited at the bottom to a sludge pit, and removes the sludge collected in the sludge pit using a sludge pump. Hereinafter, sand, sludge, and the like contained in wastewater may be referred to as contaminants. Some transport systems for transporting contaminants deposited at the bottom of ponds use mechanical devices such as screw conveyors and scrapers. However, because mechanical devices can wear out due to friction with the contaminants or be corroded by the wastewater, systems that transport contaminants using water currents have been developed in recent years (see, for example, Patent Document 1). In the transfer system of Patent Document 1, liquid is discharged from a discharge outlet into a space formed by a space-forming member, generating a water current within the space, and impurities deposited on the bottom of the pond can be sucked into the space and moved to the pit by the water current. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-165701 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the transfer system described in Patent Document 1, a pump for the transfer system is placed in a pump well formed in a pond, and the wastewater in the pump well is sucked up by the pump for the transfer system and used as a liquid to be discharged from the discharge port, which poses a problem that the transfer system becomes expensive.

[0005] In view of the above circumstances, an object of the present invention is to provide an inexpensive transport system. [Means for solving the problem]

[0006] The transport system of the present invention that solves the above object comprises: A transfer system installed in a pond where contaminants contained in a liquid settle and accumulate at the bottom, a tank disposed above the bottom for storing a contaminant collection liquid; A liquid supply pipe extending from the tank to the pond; an outlet located within the pond; A container that receives a contaminated liquid obtained by mixing the contaminants into the liquid through an inlet into a container space X1 and discharges a concentrated liquid in which the concentration of the contaminants in the liquid has increased from an outlet; a storage tank in which the outlet is disposed and which stores the concentrated liquid obtained in the container; the discharge port discharges the impurity-collecting liquid that has flowed down through the liquid transfer pipe and transfers the impurities that have accumulated on the bottom, the container delivers the liquid contained in the received mixed liquid from a delivery port to the tank; The opening area of ​​the delivery port is equal to or larger than the opening area of ​​the discharge port.

[0007] The opening area of ​​the outlet may be equal to or greater than the opening area of ​​the inlet. [Effects of the Invention]

[0008] According to the present invention, an inexpensive transport system can be provided. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a plan view of a sedimentation basin in which a transfer system corresponding to one embodiment of the present invention is arranged, viewed from above. [Figure 2] 2 is a cross-sectional view of the settling basin shown in FIG. 1 along the line AA. [Figure 3] 2(a) is a plan view of the container shown in FIG. 1, and FIG. 2(b) is a cross-sectional view taken along line BB in FIG. 2(a). [Figure 4] 2 is a front view showing a lower portion of the discharge device shown in FIG. 1, a container, and a storage tank. FIG. [Figure 5] 2 is a right side view showing the lower part of the discharge device shown in FIG. 1, a container, and a storage tank. FIG. [Figure 6] 2 is a flowchart showing the operation of the transfer system shown in FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the description of this embodiment, an example in which the transfer system of the present invention is installed in a settling basin is used. The settling basin is located upstream of a sewage treatment facility, and allows sand contained in wastewater such as sewage or rainwater to settle, and then moves the settled sand to a sand collection pit for removal.

[0011] Fig. 1 is a plan view of a settling basin in which a transfer system according to one embodiment of the present invention is disposed, as seen from above, and Fig. 2 is a cross-sectional view of the settling basin taken along line AA of Fig. 1.

[0012] As shown in Figure 1, the settling basin 1 is a rectangular basin in plan view, equipped with a bottom slope 2, a trough 3, a sand collection pit 4, a pump well 5, and a transfer system 6. Hereinafter, the long side direction of the settling basin 1 will be referred to as the longitudinal direction, and the short side direction will be referred to as the width direction. The settling basin 1 shown in Figure 1 receives wastewater from the right side of the figure. This wastewater corresponds to an example of a liquid. The received wastewater flows slowly toward the left side of the figure (see the straight arrows in Figures 1 and 2). In other words, the longitudinal direction of the settling basin is the direction of the wastewater flow, and in Figures 1 and 2, the right side is the upstream side and the left side is the downstream side. Furthermore, the leftward direction in Figures 1 and 2 is the direction in which sand is transported by the transfer system 6.

[0013] The bottom inclined surface 2 and trough 3 are formed on the bottom 1a (see Figure 2) on the upstream side of the settling basin 1. The bottom inclined surface 2 and trough 3 are located upstream of the sand collection pit 4. The trough 3 is located in the center of the settling basin 1 in the width direction and extends along the sand transport direction. This sand transport direction coincides with the flow direction of the wastewater received by the settling basin 1. The trough 3 has an open cross section with a three-quarter arc shape at the top. However, the cross section of the trough 3 may also be U-shaped, V-shaped, or the like. The total length of the trough 3 in this embodiment is 20 m. The downstream end of the trough 3 is connected to the sand collection pit 4. The bottom inclined surfaces 2 are formed on both sides of the trough 3 in the width direction so as to connect to the trough 3. Sand mixed in the wastewater flowing into the settling basin 1 settles toward the bottom 1a as it slowly flows through the upstream part of the settling basin 1. Sand that has settled toward the bottom 1a of the settling basin 1 flows down the bottom slope 2 or is directly deposited in the groove defined by the trough 3. The sand deposited in the groove defined by the trough 3 is transported to the sand collection pit 4 by the flow of water discharged from the discharge port 632.

[0014] The sand collection pit 4 is provided at the bottom 1a (see Figure 2) downstream of the settling basin 1. The sand that has settled at the bottom 1a of the settling basin 1 is collected in the sand collection pit 4. This sand corresponds to an example of contaminants, and the sand collection pit 4 corresponds to an example of an accumulation section. Inside the sand collection pit 4, an agitation nozzle 651 and a sand lifting pump 61 are provided. A total of four agitation nozzles 651 are located near each corner of the bottom of the sand collection pit 4. The agitation nozzles 651 are used to agitate the sand inside the sand collection pit 4. The sand inside the sand collection pit 4 can be agitated by discharging fluid from the tip of the agitation nozzle 651 before driving the sand lifting pump 61. The sand lifting pump 61 is located near the bottom of the sand collection pit 4 and pumps the sand collected in the sand collection pit 4 to the separator 7, which is located above the settling basin 1. One end of a sand lifting pipe 611 is connected to the sand lifting pump 61. The sand sucked by the sand lifting pump 61 is pumped up to the separation device 7 through the sand lifting pipe 611. The sand lifting pump 61 also pumps up wastewater along with the sand. Hereinafter, the sand and wastewater pumped up by the sand lifting pump 61 will be collectively referred to as sand-containing water.

[0015] The pump well 5 stores wastewater from which sand has been removed. The pump well 5 is located at the most downstream side of the settling basin 1. As shown in FIG. 2, the bottom of the pump well 5 is the deepest part of the settling basin 1. A lifting pump 51 is located inside the pump well 5. This lifting pump 51 discharges the wastewater stored in the pump well 5 out of the settling basin 1. A lifting pipe 511 is connected to the lifting pump 51. The wastewater sucked by the lifting pump 51 is sent to a settling basin (not shown) through this lifting pipe 511. FIG. 2 also shows the pond water level WL1 formed by the wastewater flowing through the settling basin 1. The position of this pond water level WL1 changes in height from the bottom of the trough 3, for example, within a range of 1 m to 5 m, depending on the amount of wastewater flowing into the settling basin 1.

[0016] The transfer system 6 includes the sand lifting pump 61 and sand lifting pipe 611, the tank 62, the first water supply pipe 63, the space forming member 64, the second water supply pipe 65, and the separator 7. The separator 7 includes a container 71, a storage tank 72, a discharge device 73, and a separation pipe 74. The separator 7 separates the sand from the wastewater contained in the sand-containing water. The separator 7 is located on the ground near the grit basin 1. The lower portion of the container 71 is located within the storage tank 72, and the upper portion of the container 71 protrudes above the storage tank 72. The container 71 is a so-called liquid cyclone to which the other end of the sand lifting pipe 611 is connected. The sand-containing water pumped up by the sand lifting pump 61 flows into the container 71. The container 71 separates the sand from the sand-containing water and sends the wastewater to the separation pipe 74. Furthermore, container 71 discharges concentrated water with an increased sand concentration into storage tank 72. Container 71 and storage tank 72 will be described in detail later. The wastewater sent directly from container 71 to separation tube 74 is sent to tank 62 through separation tube 74 together with supernatant liquid (wastewater) pumped up from storage tank 72, which will be described later. Hereinafter, the wastewater sent directly from container 71 to separation tube 74 and the supernatant liquid pumped up from storage tank 72 and sent to separation tube 74 will be collectively referred to as separated water. Furthermore, the sand and supernatant liquid stored in storage tank 72 will be collectively referred to as stored water. Note that while impurities may also be mixed in the stored water, in this embodiment, the stored water mixed with these impurities will be simply referred to as stored water, and the supernatant liquid mixed with impurities will sometimes be simply referred to as supernatant liquid. One end of the separation tube 74 is connected to the container lid 7112 of the container 71 , and the other end is inserted into the tank 62 from the upper end of the tank 62 .

[0017] The unloading device 73 is connected to the lower end of the storage tank 72 and extends diagonally upward. The unloading device 73 has a screw conveyor 731 and a drop port 732. The screw conveyor 731 is disposed within the unloading device 73. The axial direction of the screw conveyor 731 coincides with the extension direction of the unloading device 73. A motor 733 and a drive transmission mechanism 734 are fixed to the upper end portion of the unloading device 73. When the motor 733 is driven, the screw conveyor 731 rotates via the drive transmission mechanism 734. The drive transmission mechanism 734 is composed of sprockets fixed to the drive shaft of the motor 733 and the screw conveyor 731, and chains wound around each sprocket, but may also be composed of other mechanical transmission elements such as gears. Alternatively, the motor 733 and the screw conveyor 731 may be directly connected without providing the drive transmission mechanism 734. The sand contained in the concentrated water discharged into storage tank 72 settles within storage tank 72 and flows into discharge device 73 connected to storage tank 72, where it is drained and transported diagonally upward as screw conveyor 731 rotates. Drop port 732 is located near the upper end of screw conveyor 731. The sand drained by screw conveyor 731 is dropped downward from drop port 732. In other words, discharge device 73 discharges the sand contained in the water stored in storage tank 72 to the outside of storage tank 72. Note that instead of screw conveyor 731, another transport mechanism such as a belt conveyor may be used.

[0018] Fig. 3(a) is a plan view of the vessel shown in Fig. 1, and Fig. 3(b) is a cross-sectional view taken along line BB in Fig. 3(a). Fig. 3(a) and Fig. 3(b) also show a part of the sand lifting pipe 611.

[0019] As shown in FIG. 3(b), the container 71 includes a fluid introduction section 711, a throttle section 712, a discharge section 713, a fluid inlet pipe 714, and a separation tube 74. The fluid introduction section 711 is provided in the upper portion of the container 71. The upper end of the throttle section 712 is connected to the lower end of the fluid introduction section 711. The upper end of the discharge section 713 is connected to the lower end of the throttle section 712. The inner circumferential surface 71a of the container 71 is made up of the inner circumferential surface 711a of the fluid introduction section 711, the inner circumferential surface 712a of the throttle section 712, and the inner circumferential surface 713a of the discharge section 713. The inner circumferential surface 71a of the container 71 defines an internal space X1 of the container.

[0020] The fluid introduction part 711 includes a cylindrical part 7111 having a cylindrical inner circumferential surface 711a, and a container lid 7112 that closes the upper end of the cylindrical part 7111. The cylindrical part 7111 is made by processing a steel plate with a thickness of 3.2 mm into a cylindrical shape with an inner diameter of 500 mm. The container lid 7112 is made by processing a steel plate with a thickness of 6.0 mm into a ring shape with an outer diameter of 586 mm and an inner diameter of 216 mm. The shape, material, and thickness of the cylindrical part 7111 and the container lid 7112 may be selected appropriately depending on the size of the container space X1, etc.

[0021] A fluid inlet pipe 714 is connected to the upper portion of the cylindrical portion 7111. The sand lifting pump 61 and the fluid inlet pipe 714 shown in FIG. 1 are connected via the sand lifting pipe 611. The sand lifting pipe 611 and the fluid inlet pipe 714 are detachably coupled by fastening flanges at their connecting ends together with bolts. The fluid inlet pipe 714 is a pipe with an inner diameter of 100 mm. An inlet 7141 is formed at the connection between the fluid inlet pipe 714 and the cylindrical portion 7111. As indicated by the straight arrow pointing right in FIGS. 3(a) and 3(b), sand-containing water sucked up by the sand lifting pump 61 is introduced into the container space X1 through the inlet 7141 in the tangential direction of the inner circumferential surface 711a of the cylindrical portion 7111. This creates a swirling flow of sand-containing water in the container space X1.

[0022] The throttle portion 712 is disposed between the inlet 7141 and the outlet 713. In this throttle portion 712, the cross-sectional area of ​​the internal space X1 of the container decreases toward the outlet 713. In other words, the throttle portion 712 has an inverted conical inner surface 712a whose diameter gradually decreases with increasing distance from the cylindrical portion 7111. This throttle portion 712 is formed by processing a steel plate having a thickness of 3.2 mm into a conical shape, and has an inner diameter of 500 mm at the upper end and an inner diameter of 100 mm at the lower end. The material and thickness of the throttle portion 712 may be appropriately selected depending on the size of the internal space X1 of the container, the amount of narrowing, and the like. Furthermore, the throttle portion 712 may be formed so that the cross-sectional area of ​​the internal space X1 of the container decreases stepwise with increasing distance from the cylindrical portion 7111. That is, the throttle portion 712 may be formed so that the cross-sectional area of ​​the internal space X1 of the container is smaller on the outlet 7131 side than on the inlet 7141 side. The cross-sectional area of ​​the lower end of the throttle portion 712 is equal to the opening area of ​​the outlet 7131. In this embodiment, the cross-sectional area of ​​the lower end of the throttle portion 712, i.e., the opening area (cross-sectional area) of the outlet 7131 is made equal to the opening area (cross-sectional area) of the inlet 7141, but the opening area of ​​the outlet 7131 may be equal to or greater than the opening area of ​​the inlet 7141. However, if the opening area of ​​the outlet 7131 is made too small, the pressure loss in the container 71 increases, so the opening area of ​​the outlet 7131 is preferably equal to or greater than the opening area of ​​the inlet 7141. In addition, if the opening area of ​​the outlet 7131 is made too small or too large, the suction action from the storage tank 72 to the container 71, which will be described later, decreases, so it is desirable to set the opening area of ​​the outlet 7131 to be 50% or more and 150% or less of the opening area of ​​the inlet 7141. A container flange 7121 that protrudes toward the outside of the container 71 is formed at the upper end of the narrowed portion 712.

[0023] The discharge portion 713 is connected to the opposite side of the throttle portion 712 to the side to which the fluid introduction portion 711 is connected. In other words, the discharge portion 713 is connected to the lower end of the throttle portion 712. The discharge portion 713 is cylindrical with a flange 7132 formed at the lower end. The opening at the lower end of this discharge portion 713 becomes the discharge port 7131. Note that the discharge portion 713 may be omitted. In that case, the opening at the lower end of the throttle portion 712 becomes the discharge port. The flange 7132 is annular and has an outer diameter of 200 mm.

[0024] Separation pipe 74 is a pipe with an inner diameter of 200 mm. One end of separation pipe 74 is watertightly connected to container lid 7112 by welding. Alternatively, one end of separation pipe 74 may protrude into container space X1. The opening at one end of separation pipe 74 serves as outlet 741. The separated water discharged from outlet 741 is sent through separation pipe 74 to tank 62 shown in FIG. 1. In FIGS. 3(a) and 3(b), the direction of flow of the separated water is indicated by a straight arrow pointing left. The opening area of ​​outlet 741 is preferably equal to or larger than the opening area of ​​outlet 7131. This increases the amount of separated water discharged from outlet 741 and reduces pressure loss in container 71. Furthermore, the opening area of ​​outlet 741 is preferably equal to or larger than the opening area of ​​inlet 7141. This allows a larger amount of fluid to be discharged from outlet 741 than the sand-containing water flowing in from inlet 7141. In this embodiment, the opening area of ​​the outlet 741 is four times the opening area of ​​the outlet 7131 and the inlet 7141 .

[0025] Fig. 4 is a front view showing the lower part, container, and storage tank of the carry-out device shown in Fig. 1. Fig. 5 is a right side view showing the lower part, container, and storage tank of the carry-out device shown in Fig. 1.

[0026] As shown in FIG. 4 , the storage tank 72 includes a sidewall 721 that is disposed outside the container 71 and extends above the discharge port 7131, and a tank lid 722 that closes the upper end of the sidewall 721. In this embodiment, the sidewall 721 extends from below the discharge port 7131 to the height of the connection between the throttled portion 712 and the fluid introduction portion 711. A hole having the same diameter as the outer periphery of the fluid introduction portion 711 of the container 71 is formed in the center of the tank lid 722 in a plan view. The container 71 is joined to the storage tank 72 by welding the container flange 7121 to the tank lid 722 with the upper end portion of the throttled portion 712 inserted into the hole. A deodorizing pipe 7221 is provided on the tank lid 722. The storage tank 72 is supported by legs 723. The legs 723 are located at the four corners of the storage tank 72 in a plan view. 4, only the upper and lower end portions of the legs 723 are shown, with the middle portion omitted. The lower end portions of the legs 723 are in contact with the ground, so that the storage tank 72 is positioned at a predetermined height above the ground. Note that a support member for supporting the unloading device 73 is also provided at the middle portion of the extension direction of the unloading device 73, but this support member is not shown.

[0027] The upper portion of the storage tank 72 is formed as a rectangular cylinder with a substantially square shape in a plan view. As shown in FIG. 5, a tank inclined surface 721a is formed on the lower portion of the storage tank 72. The lower end of this tank inclined surface 721a is connected to the discharge device 73. Also, as shown in FIG. 4, the lower end of the storage tank 72 is notched obliquely upward at the same angle as the inclination angle of the discharge device 73. Sand contained in the concentrated water discharged from the discharge port 7131 of the container 71 slides down the tank inclined surface 721a or is deposited directly below the discharge device 73 connected to the lower end of the storage tank 72. As described above, the sand deposited in the discharge device 73 is discharged to the outside of the separation device 7 by the screw conveyor 731. A discharge pipe 735 is provided at the lower end of the discharge device 73 for discharging liquid and sand remaining in the storage tank 72 and the discharge device 73 during inspection, etc. A valve (not shown) is provided on the discharge pipe 735. 4 and 5 also show the tank water surface WL2 formed at a height facing the outlet 7131 by the supernatant liquid of the stored water discharged from the outlet 7131.

[0028] As shown in FIG. 1, the tank 62 is a rectangular carbon fiber water tank in a plan view. The tank 62 can store more than 3,000 liters of liquid. The tank 62 may be made of a metal such as stainless steel or resin. The top of the tank 62 is open, but a lid may be provided to close the top. If a lid is provided, it is desirable to provide an air inlet in the lid or the top of the tank 62, or to provide a gap between the tank 62 and the lid to allow air to pass through. As described above, the other end of the separation pipe 74 extends into the tank 62. As shown in FIG. 2, the other end of the separation pipe 74 is formed with a discharge port 742 for discharging separated water into the tank 62. The tank 62 also has a supply port 91 for supplying treated water. This treated water is water that has been treated in an aeration tank or a final sedimentation tank downstream of the grit basin 1. It is pumped up by a pump in the final sedimentation tank and supplied through a treated water supply pipe 9 by opening a valve (not shown). By providing the supply port 91, purified water can be supplied to the tank 62 without driving the sand pump 61. Purified water from a water supply system may be supplied instead of treated water. When using purified water, a water pipe may be used instead of the treated water supply pipe 9, and a faucet may be installed on top of the tank 62 instead of the valve. In other words, the tank 62 stores separated water, treated water, purified water, or a mixture of these as a sand collection liquid. Because separated water is composed of wastewater containing organic matter, it will corrode if stored in the tank 62 for a long period of time. However, storing treated water or purified water as the sand collection liquid prevents the sand collection liquid from corroding even if stored in the tank 62 for a long period of time. The tank 62 is supported by tank legs (not shown) so that its bottom is located 10 m above the water level WL1 of the settling basin 1 when it is at its highest water level. An overflow pipe 621 is connected to the upper end of the tank 62. The tip of the overflow pipe 621 is located within the settling basin 1. The overflow pipe 621 returns the sand collecting liquid near the upper end of the tank 62 to the settling basin 1 when the sand collecting liquid has been supplied up to near the upper end of the tank 62 so that the sand collecting liquid does not overflow from the tank 62. In addition, a water level sensor 622 is provided in the tank 62 to detect the water level of the sand collecting liquid stored in the tank.

[0029] The first water supply pipe 63 is connected to the underside of the tank 62. This first water supply pipe 63 corresponds to an example of a liquid supply pipe. The first water supply pipe 63 extends into the sedimentation basin 1. In this embodiment, the first water supply pipe 63 extends to near the bottom 1a of the sedimentation basin 1, and its tip is bent downstream near the bottom 1a, which is the direction of sand transport. This bent tip forms a sand collection nozzle. The first water supply pipe 63 is provided with a first electric valve 631. When the first electric valve 631 is opened, the sand collecting liquid stored in the tank 62 is sent to the bottom 1a of the sedimentation basin 1 through the first water supply pipe 63. That is, the sand collecting liquid flows down through the first water supply pipe 63 due to potential energy. A discharge port 632 is formed at the tip of the first water supply pipe 63. The flowing sand collecting liquid is discharged from the discharge port 632 in the direction of sand transport. This discharge port 632 extends into the internal space defined by the space forming member 64. The discharge port 632 is an elongated hole formed by flattening the tip of the first water supply pipe 63, which has a diameter of 80 mm. The discharge port 632 has a flat shape that is flattened in the height direction and expanded in the width direction. The opening length W of the discharge port 632 in the width direction is 120 mm, and the height H of the discharge port 632 is 20 mm. By making the discharge port 632 in this flat shape, the flow rate of the discharged sand collecting liquid can be increased compared to a circular shape.

[0030] The discharge port 632 and the space-forming member 64 are disposed in a groove defined by the trough 3. The space-forming member 64 extends along the trough 3. Although the overall length of the space-forming member 64 is approximately the same as the overall length of the trough 3, it is disposed slightly downstream relative to the trough 3, so that its downstream end protrudes slightly into the sand collection pit 4. The extension direction of the space-forming member 64 also corresponds to the direction of sand transport. The space-forming member 64 is a stainless steel flat plate formed to have an arc-shaped cross section. However, the space-forming member 64 may also be formed by processing a plate of another material, or by injection molding or extrusion molding. In this embodiment, the space-forming member 64 is a cylinder with an inner diameter of 156 mm, with the lower portion cut out. An opening is provided at the bottom facing the bottom of the trough 3, with a gap between the bottom and the space-forming member 64. The radial center of the space-forming member 64 approximately coincides with the radial center of the trough 3. The cross-sectional shape of the space forming member 64 may be a rectangle or the like with an opening at the center of the lower side in the width direction.

[0031] The second water supply pipe 65 is also connected to the underside of the tank 62. The agitation nozzle 651 described above is formed at the tip of the second water supply pipe 65. A second electric valve 652 is provided on the second water supply pipe 65. When the second electric valve 652 is opened, the sand collecting liquid stored in the tank 62 is sent out toward the agitation nozzle 651 through the second water supply pipe 65. That is, the sand collecting liquid stored in the tank 62 flows down inside the second water supply pipe 65 due to potential energy. The flowing sand collecting liquid is discharged from the tips of the agitation nozzles 651 located near the four corners of the sand collection pit 4 toward the center of the sand collection pit 4 in the width direction. This agitates the sand in the sand collection pit 4.

[0032] Next, we will explain the driving method and operation of this transfer system 6. Figure 6 is a flowchart showing the operation of the transfer system shown in Figure 1.

[0033] The operation of the transfer system 6 is controlled by a control device (not shown). The transfer system 6 performs a transfer operation at a predetermined time when a certain amount of sand has accumulated on the bottom of the settling basin 1 shown in FIG. 1 . The predetermined time may be periodically, such as once a month, or may be when the total flow rate of wastewater flowing into or discharged from the settling basin 1 reaches a certain amount. In the transfer operation, the water level of the tank 62 is first detected by the water level sensor 622 (step S1). If the water level in the tank 62 is below a predetermined level (NO in step S1), treated water is supplied from the treated water supply pipe 9 until the water level reaches the predetermined level (step S2). The predetermined water level here refers to the water level at which the sand collection liquid stored in the tank 62 is sufficient to stir the sand collection pit 4 twice and to transfer the sand accumulated in the groove defined by the trough 3 to the sand collection pit 4. However, as described below, separated water begins to be supplied to the tank 62 shortly after the sand raising pump 61 begins operating. Therefore, the predetermined water level need only be higher than the water level storing the amount of water required to stir the sand collection pit 4 once. When the water level in the tank 62 reaches or exceeds the predetermined water level (YES in step S1), the supply of treated water is stopped, and the second electric valve 652 is opened (step S3). As described above, when the second electric valve 652 is opened, the sand collection liquid stored in the tank 62 flows down the second water supply pipe 65 and is discharged by water pressure from the tip of the stirring nozzle 651 toward the center of the width of the sand collection pit 4. This stirs the sand in the sand collection pit 4, allowing the sand accumulated at both ends of the width of the sand collection pit 4 to move toward the sand raising pump 61. Furthermore, if the sand raising pump 61 is submerged in sand, stirring the sand can raise the sand that is submerging the sand raising pump 61, thereby reducing the concentration of sand around the sand raising pump 61. This allows the sand to be stirred up. This prevents the sand lifting pump 61 from becoming clogged when the sand lifting pump 61 is started. After a first predetermined time has elapsed since the second electric valve 652 was opened (YES in step S4), the second electric valve 652 is closed (step S5). This first predetermined time is set to a time sufficient for the sand in the sand collection pit 4 to be stirred. Steps S3 to S5 described above correspond to an example of the first stirring step.

[0034] Next, the operation of the discharge device 73 is started (step S10), and the first electric valve 631 is opened (step S21). While the discharge device 73 is being driven, sand accumulated in the lower portion of the discharge device 73 is transported diagonally upward along the discharge path of the discharge device 73. The sand transported by the screw conveyor 731 is drained in the latter half of the discharge path, which is higher than the tank water level WL2, while being transported. Then, the sand that reaches the upper end of the discharge path of the discharge device 73 is dropped downward from the drop port 732. After the discharge device 73 is started to be driven, the sand lifting pump 61 is then started to be driven. This start of driving starts the inflow of sand-containing water into the container 71 (step S11). Because the sand-containing water flows in from the tangential direction of the inner circumferential surface 711a of the cylindrical portion 7111, a swirling flow of sand-containing water is formed near the inner circumferential surface 71a of the container 71 in the container interior space X1. The sand contained in the sand-containing water has a greater specific gravity than the wastewater, and is therefore pressed against the inner circumferential surface 71a of the container 71 by centrifugal force, and gradually falls downward while circulating along the inner circumferential surface 71a. Meanwhile, the wastewater from which the sand has been removed from the sand-containing water gathers in the radial center of the container 71, generating an upward flow. This upward flow causes the wastewater that has gathered in the center to be discharged as separated water from a discharge port 741 at the top end of the container 71. The separated water that has been discharged passes through a separation pipe 74 and is discharged into the tank 62 from a discharge port 742 at the other end of the separation pipe 74.

[0035] In the container space X1, the sand gradually falls downward while swirling along the inner circumferential surface 71a, and begins to be discharged as concentrated water from the discharge port 7131 together with a certain amount of wastewater (step S12). The concentrated water is discharged radially from the discharge port 7131 due to the centrifugal force of the swirling flow. In FIGS. 4 and 5, the direction of concentrated water discharge is indicated by curved arrows. If the storage tank 72 is empty when the discharge of concentrated water begins, the water level WL2 in the storage tank 72 gradually rises. Furthermore, the sand contained in the water stored in the storage tank 72 settles toward the bottom of the storage tank 72 due to its own weight and accumulates in the lower portion of the discharge device 73. Note that as the amount of accumulated sand increases, the sand that does not fit into the lower portion of the discharge device 73 also accumulates in the lower portion of the storage tank 72.

[0036] As the tank water level WL2 rises and reaches a height position facing the discharge port 7131 (YES in step S13), as shown in FIGS. 4 and 5, the supernatant liquid (polluted water) of the stored water in the portion facing the discharge port 7131 is sucked into the discharge port 7131 (step S14). This supernatant liquid sucked into the discharge port 7131 corresponds to an example of a liquid component. The supernatant liquid is sucked from the radial center portion of the discharge port 7131 by the upward flow in the container 71. In FIGS. 4 and 5, the direction in which the supernatant liquid is sucked is indicated by a straight arrow. When this supernatant liquid is sucked into the discharge port 7131, the air around the discharge port 7131 is also sucked into the discharge port 7131. In other words, a volume of fluid (supernatant liquid and air) greater than the volume of concentrated water being discharged is sucked into the discharge port 7131. In this embodiment, the container 71 is formed with a delivery port 741 having a larger opening area than the discharge port 7131, allowing a large amount of fluid to be delivered from the delivery port 741. As a result, fluid can be easily sucked through the discharge port 7131. Even if a volume of fluid greater than the volume of concentrated water being discharged is sucked through the discharge port 7131, it can still be delivered through the delivery port 741. When the supernatant liquid and air are being sucked through the discharge port 7131, a balanced state is formed in which the volume of concentrated water discharged from the discharge port 7131 to the storage tank 72 and the volume of the supernatant liquid sucked through the discharge port 7131 into the container space X1 are approximately equal. The volume of air sucked into the discharge port 7131 is 1 / 5 or less of the volume of the supernatant liquid. In this embodiment, a flange 7132 extending horizontally is formed around the discharge port 7131, making it difficult for air above the discharge port 7131 to be sucked into the discharge port 7131. In addition, the flange 7132 suppresses rippling of the tank water surface WL2 near the discharge port 7131. As a result, air is less likely to be sucked into the discharge port 7131, and the ratio of supernatant liquid to air sucked into the discharge port 7131 is increased. Furthermore, the flange 7132 makes it easier for the concentrated water discharged from the discharge port 7131 to be discharged orderly in the radial direction. As a result, sand contained in the concentrated water discharged from the discharge port 7131 is prevented from mixing with the supernatant liquid sucked in from the radial center of the discharge port 7131.The height position at which the tank water surface WL2 faces the discharge port 7131 refers to the position at which the tank water surface WL2 reaches a height at which the distance between the tank water surface WL2 and the discharge port 7131 is 0 mm or more and 20 mm or less. Here, as described above, because the concentrated water is discharged radially from the discharge port 7131, it is unlikely that sand contained in the concentrated water will be sucked in from the center of the discharge port 7131. In addition, sand has a high specific gravity and tends to settle quickly to the bottom of the storage tank 72. Therefore, even if a strong upward flow is formed in the container 71 and the suction force generated at the discharge port 7131 is strong, the amount of sand sucked into the container 71 is limited to an extremely small amount. Because this extremely small amount of sand has a higher specific gravity than the supernatant liquid, most of it is repelled radially from the upward flow in the container 71, absorbed into the swirling flow, and then discharged again from the discharge port 7131 into the storage tank 72. As described above, air is also sucked in from outlet 7131, and the upward flow occurring in the center of container 71 is a flow of fluid with a low specific gravity that is mixed with the sucked air. Therefore, the difference in specific gravity between the fluid that mainly constitutes the upward flow and the sand becomes greater, and the sand with a high specific gravity is more likely to be expelled in the radial direction.

[0037] If the rate of sand-containing water flowing into container 71 is less than 2.0 m3 / min, the amount of supernatant liquid drawn into outlet 7131 will be less than the concentrated water discharged from outlet 7131, causing the tank water level WL2 to rise beyond outlet 7131. However, when tank water level WL2 reaches outlet 7131, outlet 7131 becomes blocked by the accumulated water, reducing the amount of concentrated water discharged from outlet 7131. That is, the resistance caused by the reduction in the cross-sectional area of ​​container space X1 at throttle section 712, combined with the water pressure of the accumulated water acting on outlet 7131, makes it difficult for concentrated water to be discharged from outlet 7131. As tank water level WL2 rises, the water pressure of the accumulated water acting on outlet 7131 increases, reducing the amount of concentrated water discharged from outlet 7131 and increasing the amount of separated water delivered from delivery port 741. As a result, the tank water level WL2 reaches a certain height and is maintained at that height. Furthermore, in this embodiment, the height position of the discharge port 742 is lower than the height position of the discharge port 7131 of the container 71, so when the liquid level of the sand-collecting liquid stored in the tank 62 is lower than the tank water level WL2 and the separation tube 74 is filled with separated water, the separated water tends to flow out of the discharge port 742 due to the siphon principle. This action also prevents the tank water level WL2 from rising, and further, there is a possibility that the amount of supernatant liquid greater than the amount of concentrated liquid discharged from the discharge port 7131 will be sucked into the discharge port 7131, causing the tank water level WL2 to drop.

[0038] On the other hand, by opening the first electric valve 631 in step S21 described above, the sand collecting liquid stored in the tank 62 flows down the first water supply pipe 63 and is discharged from the discharge port 632 in the sand transfer direction due to water pressure. This causes a flow of liquid within the space forming member 64, resulting in a pressure difference between the inside and outside of the space forming member 64. The sand accumulated in the groove defined by the trough 3 is sucked into the internal space of the space forming member 64 from the opening on the lower side of the space forming member 64. Furthermore, in this internal space, the sucked sand moves toward the sand collection pit 4 due to the flow of liquid. The sand accumulated in the groove defined by the trough 3 is transported to the sand collection pit 4 and collected there. When a fourth predetermined time has elapsed since the first electric valve 631 was opened (YES in step S22), the first electric valve 631 is closed (step S23). This fourth predetermined time is set to a time sufficient to transport the sand accumulated in the groove defined by the trough 3 to the sand collection pit 4. Steps S21 to S23 described above correspond to an example of a sand collection process.

[0039] After the first motor-operated valve 631 is closed in step S23, the second motor-operated valve 652 is immediately opened (step S24). When the second motor-operated valve 652 is opened, the sand collection liquid stored in the tank 62 flows down the second water supply pipe 65 and is discharged by water pressure from the tip of the agitation nozzle 651 toward the center of the width of the sand collection pit 4. This agitates the sand in the sand collection pit 4, moving the sand at both ends of the width of the sand collection pit 4 toward the sand lifting pump 61. After a fifth predetermined time has elapsed since the second motor-operated valve 652 was opened (YES in step S25), the second motor-operated valve 652 is closed (step S26). This fifth predetermined time is set to a time sufficient to move the sand at both ends of the width of the sand collection pit 4 toward the vicinity of the sand lifting pump 61. This reduces the amount of sand remaining in the sand collection pit 4 after the operation of the sand lifting pump 61 is stopped. Steps S24 to S26 described above correspond to an example of the second agitation process.

[0040] After a second predetermined time has elapsed since the start of operation of the sand pump 61 (YES in step S15), the operation of the sand pump 61 is stopped (step S16). This second predetermined time is the sum of the fourth predetermined time and the fifth predetermined time plus several tens of seconds. Therefore, the processing from steps S21 to S26 described above is completed shortly before the sand pump 61 is stopped. Stopping the sand pump 61 also stops the inflow of sand-containing water into the container 71, the discharge of concentrated water into the storage tank 72, the suction of supernatant liquid, and the delivery of separated water. Separated water continues to be supplied to the tank 62 until the stop. If the amount of separated water delivered is large and the sand collecting liquid reaches near the top of the tank 62 to which the overflow pipe 621 is connected, the sand collecting liquid flows into the settling basin 1 through the overflow pipe 621. Steps S11 to S16 described above correspond to an example of an inflow process in which sand-containing liquid is introduced into the container 71. Steps S14 to S16 correspond to an example of a discharge / suction step in which the concentrated liquid is discharged from the discharge port 7131 to the storage tank 72 while the supernatant liquid in the storage tank 72 is sucked from the discharge port 7131.

[0041] When a third predetermined time has elapsed since the operation of the sand raising pump 61 was stopped (YES in step S17), the operation of the discharge device 73 is stopped (step S18). Steps S10 to S18 described above correspond to an example of a discharge step for discharging sand to the outside of the separation device 7. This third predetermined time is the total time taken for the sand contained in the concentrated water discharged from the discharge port 7131 to settle to the lower part of the discharge device 73 and the time taken for the sand to be transported from the lower part of the discharge device 73 to the drop port 732. Note that instead of determining whether the third predetermined time has elapsed, a sand presence / absence sensor that detects the presence or absence of sand in the lower part of the discharge device 73 may be provided in the discharge device 73, and whether or not such detection has occurred may be determined. This completes the operation of the transfer system 6. Except when the amount of sand-containing water flowing into the container 71 is less than 2.0 m3 / min, while the discharge device 73 is operating, the tank water level WL2 is below or approximately aligned with the discharge port 7131, so sand can be transported while draining, even if the discharge path is short. Because the discharge path extends diagonally upward, shortening the discharge path shortens the width and height of the discharge device 73. As a result, the separation device 7 can be made more compact.

[0042] According to the transfer system 6 described above, the sand collecting liquid stored in the tank 62 is discharged from the discharge port 632 by the water pressure of the sand collecting liquid, so a pump for discharge can be omitted and the transfer system 6 can be constructed inexpensively. Furthermore, since the separated water, which is obtained by separating the sand from the sand-containing water pumped up from the settling basin 1 by the separator 7, is stored in the tank 62 as the sand collecting liquid, the electricity required to pump the sand collecting liquid can be omitted. Furthermore, unlike when sand-containing water is used as the sand collecting liquid, the return of sand to the settling basin 1 can be suppressed.

[0043] The present invention is not limited to the above-described embodiment and various modifications can be made within the scope of the claims. For example, in this embodiment, the transfer system 6 is described as being applied to a settling basin 1, but it may also be applied to a settling basin. In addition, in this embodiment, sand accumulated in the trough 3 is transferred to the sand collection pit 4 by discharging a sand collection liquid into the internal space defined by the space-forming member 64. However, the space-forming member 64 may not be provided, and the sand may be transferred to the sand collection pit 4 by discharging a sand collection liquid toward the sand and pushing it with a water flow. In addition, while the transfer system 6 is described as being applied to a settling basin 1 that collects sand while retaining wastewater in the settling basin 1, the transfer system 6 may also be applied to a so-called low-pressure sand collection settling basin 1 that collects sand after draining wastewater from the settling basin 1. When applied to a low-pressure sand collection settling basin 1, the sand collection liquid may be discharged toward the sidewall surface defining the settling basin 1, and the sand at the bottom 1a may be transferred by allowing the sand collection liquid to flow down along the sidewall surface. In this case, the discharge port 632 may be located in the upper part of the settling basin 1 if it is located within the settling basin 1. The discharge pressure required for the low-pressure sand collection method is significantly lower, about 0.5%, than the discharge pressure required for the high-pressure sand collection method, in which wastewater remains in the settling basin 1 and a sand collection liquid is discharged toward the sand, forcing the sand with a water flow and transporting it to the sand collection pit 4. Therefore, the tank 62 may be located lower than in this embodiment. The tank 62 may be located above the bottom 1a of the settling basin 1, for example, within the settling basin 1. Furthermore, in this embodiment, the wastewater separated from the sand by the separator 7 is stored in the tank 62 as the sand collection liquid. However, only treated water or purified water supplied from the treated water supply pipe 9 may be stored in the tank 62. Furthermore, the separator 7 may be omitted, and sand-containing water may be stored in the tank 62 as the sand collection liquid, and the supernatant liquid of the stored sand-containing water may be discharged from the discharge port 632. In this case, a discharge device 73 may be connected to the lower end of the tank 62 .

[0044] The transport system of the present invention described above includes: A transfer system installed in a pond where contaminants contained in a liquid settle and accumulate at the bottom, a tank disposed above the bottom and configured to store a sand collecting liquid; A liquid supply pipe extending from the tank to the pond; a space forming member extending along the bottom portion, forming an internal space, and having an opening at a lower portion thereof spaced apart from the bottom portion; a discharge port disposed within the pond; the discharge port discharges the sand collecting liquid that has flowed down through the liquid feed pipe due to potential energy into the internal space, The opening functions as a suction port that sucks impurities deposited on the bottom into the internal space by discharging the sand collecting liquid from the discharge port, The space-forming member is characterized by functioning as a path along which impurities sucked into the internal space move downstream in the direction of discharge of the sand collecting liquid as the sand collecting liquid is discharged from the discharge outlet.

[0045] Also, a transfer system provided in a pond where impurities mixed in liquid settle and accumulate at the bottom, a tank disposed above the bottom and configured to store a sand collecting liquid; A liquid supply pipe extending from the tank to the pond; a discharge port disposed within the pond; The discharge port may be configured to discharge the sand collecting liquid that has flowed down through the liquid supply pipe and transport any impurities that have accumulated on the bottom.

[0046] Since the contaminants deposited on the bottom are transported using the sand collecting liquid stored in the tank, a pump for the transport system is not required, and the transport system can be constructed inexpensively.

[0047] Here, the discharge port may discharge the sand collecting liquid that has flowed down through the liquid supply pipe toward the impurities accumulated on the bottom, or toward a side wall surface that defines the pond. Alternatively, the discharge port may discharge the sand collecting liquid that has flowed down through the liquid supply pipe at the bottom in the direction in which the impurities are being transferred. The discharge port may also be formed at the tip of the liquid supply pipe.

[0048] The transfer system includes a pump that pumps up the impurities deposited at the bottom, The tank may be configured to store the liquid pumped up by the pump together with the impurities as a sand collecting liquid.

[0049] According to this aspect, the sand collecting liquid can be stored in the tank by using the pump.

[0050] Here, the pump may be disposed in a collection area formed in the pond where impurities are collected.

[0051] The transfer system further comprises a separation device for separating the liquid and the solid, the pump sends the impurities and the liquid pumped with the impurities to the separation device; The separation device may supply the separated liquid to the tank as the sand collecting liquid.

[0052] In this aspect, the liquid obtained in the separation device is used as the sand collecting liquid, so that contaminants can be prevented from being returned to the settling basin.

[0053] Here, the separating device may include a liquid cyclone.

[0054] The tank may also store liquid obtained from sources other than the pond as the sand collecting liquid.

[0055] This allows the sand collecting liquid to be supplied to the tank even before the pump is driven.

[0056] Here, the tank may store treated water treated in a sewage treatment facility as the sand collecting liquid. Alternatively, the tank may store purified water as the sand collecting liquid. By storing the treated water or purified water as the sand collecting liquid, corrosion of the sand collecting liquid can be suppressed even if the sand collecting liquid is stored in the tank for a long period of time.

[0057] In addition, the above-described transport system A transfer system installed in a pond where contaminants contained in a liquid settle and accumulate at the bottom, a tank disposed above the bottom and configured to store a sand collecting liquid; A liquid supply pipe extending from the tank to the pond; a discharge port disposed within the pond; The discharge outlet discharges the sand collection liquid that has flowed down through the liquid supply pipe, draining the liquid from the pond and transporting any impurities that have accumulated on the bottom.

[0058] In addition, the above-described transport system A transfer system installed in a pond where sand mixed in the liquid settles and accumulates at the bottom. , a tank disposed above the bottom and configured to store a sand collecting liquid; A liquid supply pipe extending from the tank to the pond; an outlet located within the pond; a container for receiving a sand-mixed liquid in which the sand has been mixed into the liquid, and for discharging a concentrated liquid in which the concentration of the sand in the liquid has been increased from a discharge port; a storage tank in which the outlet is disposed and which stores the concentrated liquid obtained in the container; a conveying device having a lower end portion of a conveying path extending obliquely upward and connected to a lower end of the storage tank, and an upper end portion of the conveying path being disposed above the discharge port; a separation tube having one end connected to the container and the other end extending into the tank; the discharge port discharges the sand collecting liquid that has flowed down through the liquid transfer pipe from the pond in a state in which the liquid has been drained, and transfers the sand that has accumulated on the bottom of the pond; The container sends the liquid in the received sand-containing liquid through the separation pipe to the tank, the storage tank collects the sand in the concentrated solution at a lower end portion of the discharge device; The discharge device is characterized in that the sand collected at the lower end portion of the discharge device is discharged upward from the lower end portion while draining water at a portion higher than the liquid level, with the liquid level in the storage tank lowered to a position below the discharge outlet or approximately coincident with the discharge outlet.

[0059] The liquid supply pipe may be connected to the bottom surface of the tank. [Explanation of symbols]

[0060] 1. Settling basin 1a bottom 6. Transport System 62 Tank 63 1st water supply pipe 632 Discharge port

Claims

1. A transfer system installed in a pond where contaminants contained in a liquid settle and accumulate at the bottom, a tank disposed above the bottom for storing a contaminant collection liquid; A liquid supply pipe extending from the tank to the pond; an outlet located within the pond; a container that receives a contaminated liquid obtained by mixing the contaminants into the liquid through an inlet into a space within the container, and discharges a concentrated liquid in which the concentration of the contaminants in the liquid has increased through an outlet; a storage tank in which the outlet is disposed and which stores the concentrated liquid obtained in the container; the discharge port discharges the impurity-collecting liquid that has flowed down through the liquid transfer pipe and transfers the impurities that have accumulated on the bottom, the container delivers the liquid contained in the received mixed liquid from a delivery port to the tank; A transfer system characterized in that the opening area of ​​the delivery port is equal to or greater than the opening area of ​​the discharge port.

2. 2. The transfer system according to claim 1, wherein the opening area of ​​the outlet is equal to or larger than the opening area of ​​the inlet.

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