JP2008303558A - Sand collecting equipment and sand collecting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide sand collecting equipment for a wastewater sand basin which can perform a sand collecting operation under low pressure in a normal water-flowing state with a high degree of efficiency with low energy consumption, and a sand collecting method. <P>SOLUTION: The plurality of sand basins are juxtaposed in the flowing direction of wastewater. A sand collecting pit 20 is formed on the bottom surface of each of the sand basins. Since the sand collecting operation is performed by means of a low-pressure sand-collecting system while the flow of the wastewater is constantly maintained, an entrance gate 12 is provided at the inflow side so that the inflow of the wastewater into the sand basin 10 can be individually inhibited, and an exit gate 14 is provided at the outflow side so that the sand basin during the sand collecting operation can be separated from the other sand basins during the passage of the water. The entrance gate 12 and the exit gate 14 are closed only in one sand basin 10 at a low flow rate at night etc.; and sedimentary sand accumulated in the sand basin 10 is accumulated in the sand collecting pit 20 by means of a spray of water from a nozzle 26, and discharged by a sand lifting pump 32, so that the sand collecting operation can be performed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sand collecting device and a sand collecting method in a sewer always under water flow, and can be used for efficient sand collection in a sewage settling basin in a combined sewer or a divert sewer. Here, sand collection refers to a series of operations from collecting sand accumulated in a settling basin to a sand collection pit, which is a predetermined part of the settling pond, and discharging it from the sand collection pit to a settling collection site such as a sand set separator. Means an operation.

  The sewage sedimentation basin in the combined sewerage system and the diversion sewerage system is constantly passing water. Conventionally, a screw conveyor type sand collection device is used to collect and discharge the sediment collected in the sedimentation basin (Patent Document 1). In addition, a so-called high-pressure sand collecting device or medium-pressure sand collecting device (Patent Document 2) using a jet water pressure from a nozzle has been used. That is, in the screw conveyor type sand collecting device, the sand settling on the lower surface of the settling basin is pumped together with the sewage by the screw conveyor, and the settling separator separates the settling sand. In addition, in high-pressure sand collectors and medium-pressure sand collectors using jet water pressure, spraying pressurized water along the bottom of the sand basin collects sediment in the sand collection pit by water pressure, and sewage is collected by a jet pump installed in the sand collection pit. At the same time, the sand was lifted and the sand was separated by a sand set separator.

On the other hand, as a method for collecting sand at a low pressure, a type (so-called low-pressure sand collecting method) proposed by the applicant of this application is used for a rainwater settling basin in a diversion type or combined sewer system. Yes. That is, in the case of a rainwater settling basin, in normal cases, when the weather recovers, there is no water flow, and on the other hand, a sand collection pit provided in the longitudinal direction at the center of the bottom of the settling basin is provided with a sand pump. And the bottom of a sand basin is inclined so that both sides may become high, and the watering nozzle is opening in the both sides site | part of this heightened bottom of a sand basin. Water is sprayed along the bottom of the sand basin from the water nozzle, and the sand collected on the bottom of the sand basin is made to flow down along the inclined surface by spray water, and the sand is collected in the sand collection pit, and the sand is mixed with water. The system is configured to perform sand suction separation by sucking and transporting (sand lifting) to a sand settling machine using a sand pump provided in the sand collecting pit. Since the sand basin is empty at the time of sand collection, the sand can flow down to the sand collection pit along the bottom of the sand basin even with low-pressure water flow (spray water). A low-pressure pump can be used as a sand pump that can collect the sand collected in the sand collecting pit together with the sewage (Patent Document 3). As described above, the low-pressure sand collection method is to collect the sediment deposited on the bottom of the settling basin by collecting water in the sand collection pit by spraying water along the bottom of the settling basin in a substantially empty state. This is a sand collection method in which sand is pumped together with sewage collected in the pump.
JP 2004-160417 A JP-A-8-229310 Japanese Patent Laid-Open No. 7-100306

  Since the screw conveyor type sand collecting device is a mechanical type, there is a problem that maintenance is complicated as a sand collecting device for a sewage settling basin through which water always flows. The so-called high-pressure sand collection device and medium-pressure sand collection device collect sediment in the sand collection pit by the jet water pressure and discharge it by a jet pump. Therefore, maintenance is easy, but a high-lift pump is required and power consumption is large. Also, there was a problem that sand collection efficiency was not high.

  The so-called low-pressure sand collection system is intended for use in rainwater settling basins, and in order to collect and discharge sediments with virtually no empty sedimentation basins in the absence of water flow, In addition to being able to lower the pressure, there is an advantage that a pump with a low head is good. However, it is necessary to prevent the inflow of sewage into the settling basin during sand collection and to empty the settling basin, and it has been considered to use this method for sewage settling basins that require constant water flow. There was no.

  The present invention has been made in view of the problems of the prior art, and in a sewage and sand basin of a combined sewer or a shunt sewer that is constantly flowing, it can be collected with low energy consumption and high efficiency without complicating maintenance. The purpose is to be able to do sand.

  The sewer where the sand collecting device of the present invention is installed is always under water flow. A plurality of sand basins are provided in parallel with the sewage flow direction. Each sand basin has a sand collecting pit formed on the bottom surface, and includes a sand collecting means by a water flow to the sand collecting pit and a sand discharging means from the sand collecting pit. In order to collect the low-pressure sand collection method while maintaining the flow of sewage at all times, the sedimentation basin is provided with an inlet gate on the inflow side to prevent the inflow of sewage individually, and the outflow side is a pump. If the well is individualized, or if the pump well is shared by multiple sand basins, an outlet gate is provided in each sand basin to separate the sand basins, and in combination with the prevention of inflow of sewage, Can be empty. By sequentially closing the entrance gate at low flow rates such as at night, the inflow of sewage into the settling basin is prevented, and the settling basin is substantially emptied. Sand collection operation is performed by accumulating the sediment deposited in the pond in a sand collection pit by low-pressure water flow along the bottom of the sand basin and discharging it with a sand pump.

  Sand collection from multiple sand basins is performed at specific times when the amount of water is low, such as at night. When this time zone is detected by the timer, the sand collecting operation from the sand basin is sequentially performed. For example, only one settling basin is closed, the remaining settling basins are opened, and sand collection, that is, accumulation and discharge of settling sand is performed in the closed settling basins. Since the entrance gates of the settling basins other than the settling basin in the sand remain open, the circulation and discharge of sewage continues in other settling ponds. After the sand collection work from the closed sand basin is completed, the gate of the sand collection pond that has completed sand collection is opened, the inflow of sewage is resumed, and the gate of the sand basin that collects sand is then closed and the sand basin Evacuate and perform sand collection work in the same way. In this way, sand collection from the sand basins is sequentially performed, and when the sand collection from all the sand basins is completed, the work in this time zone is completed.

  Multiple sand basins are installed in parallel, and the inflow of sewage into each sand basin can be controlled individually, and the flow of sewage into multiple sand basins is sequentially stopped at low flow rates such as at midnight, and the remaining By separating from the sedimentation basin, the sedimentation basin is substantially emptied during the stoppage of the sewage sewage. By collecting in a pit and discharging with a sand pump, it is possible to collect sand using the low-pressure sand collection method while ensuring the circulation of waste water. And efficient sand collection work can be realized.

  Hereinafter, the case where the present invention is applied to a sewage settling basin of a diversion sewer will be described. However, the present invention is also applicable to a sewage settling basin in a combined sewer. In FIG. 1, reference numeral 8 denotes a sewage inflow pipe in a diversion sewer, and three sand basins 10 are provided in parallel in the direction of flow of sewage from the sewage inflow pipe 8 (arrow). When distinguishing the three sand basins 10, subscripts such as 10a, 10b, 10c shall be attached. An inlet gate 12 (12a, 12b, 12c) is provided at the inlet of each sand basin 10, and an outlet gate 14 (14a, 14b, 14c) is provided at the outlet. In the diversion sewer, sewage is always in a water-flowing state, and the inflow gate 12 and the outlet gate 14 are normally open. The inflow gate 12 and the outlet gate 14 are electrically operated, and an electric motor for opening / closing control thereof is provided. The electric motor for driving the gates 12 and 14 is not shown in FIG. 1, but is schematically indicated by M12 and M14 in FIG. In FIG. 1, a pump well 16 is arranged downstream of the exit gate 14 from each sand basin. In this embodiment, the pump well 16 is shared by the sand basins 10a, 10b, 10c. The sewage after passing through the sand basin 10 is sent to a sewage treatment facility such as an activated sludge treatment facility by a drainage pump 18. In this embodiment, the exit gates 14a, 14b, and 14c function as separation means for separating the sewage settling basin during sand collection from the sewage settling basin under water in the present invention.

  The sand collection method in the sand settling basin 10 is the same as that proposed and widely adopted by the same applicant as the present applicant as a so-called low pressure sand collection method in the rainwater settling basin. This sand collection method has been devised so that it can also be used for collecting sand in a sewage settling basin where water is constantly passed. The sand collection method in the sand basin 10 will be described in detail. A sand collection pit 20 (FIG. 2) extends in the longitudinal direction on the bottom surface of the sand basin 10. The sand collecting pit 20 is located at the lowest part of the sand basin, and both sides have inclined surfaces 22 (FIG. 3) extending to the side of the sand basin 10-1. Narrow and shallow troughs 24 extend in the width direction on the inclined surface 22 at intervals, and water spray nozzles 26 are opened near the side of the sand basin 10-1 between the troughs 24. The nozzle 26 communicates with a water supply source such as a sedimentation basin (not shown) via a water supply pipe 28 (which constitutes the sand collection means of the present invention with the water spray nozzle 26 shown in FIG. 2) for water spraying during sand collection. The water supply pipe 28 is provided with a water supply pump (sand sediment discharge means of the present invention) 30. A sand pump 32 (sand discharge means for discharging sand and sewage according to the present invention) is provided at the center of the sand collecting pit 20 in the longitudinal direction. The suction port 32-1 of the sand pump 32 is open near the bottom of the sand collection pit 20, and the discharge port 32-2 is connected to a sand settling machine (not shown) via a sand lifting pipe 34.

  In FIG. 2, a control circuit 36 is provided for controlling the gates 12 (12a, 12b, 12c), 14 (14a, 14b, 14c), motors M12, M14 and pumps 18, 30, 32 in the sand basin. The control circuit may be constituted by a microcomputer. The timer 38 is provided for controlling sand collection at night according to the embodiment of the present invention.

  Next, the sand collecting work of the present invention will be described with reference to the schematic flowchart of FIG. 4. When the processing is started, in step 50, it is checked by the timer 38 whether or not the time for starting the sand collecting work is reached. The sewage settling basin always has water flow, while the sand basins 10a, 10b, and 10c collect sand and prevent the sewage from flowing into the respective settling basins. In this invention, the inflow of sewage to the sand basins 10a, 10b, and 10c is sequentially blocked at night when the amount of water flow is low, for example, between 2 am and 4 am. By draining the sand basin where the water is blocked to become empty, low pressure sand collection is performed. In step 50, it is determined whether or not the start time of the sand collection work has come. If not, normal control is performed in step 52. Normally, the gates 12a, 12b, 12c and the gates 14a, 14b, 14c are open, and the sewage flows through all the sewage settling basins 10a, 10b, 10c. It is carried out to the processing part.

  When it is determined that the specific time for performing the sand collection work is reached, the process proceeds from step 50 to step 54a and the subsequent steps, and the sand collection work is performed in the first sand settling basin 10a. First, in step 54a, in order to close the entrance gate 12a to the sand basin 10a, the gate is closed as indicated by an imaginary line 12 'in FIG. 2 by the drive signal to the drive motor M12 of the entrance gate 12a, and the sewage to the sand basin 10a is closed. Stop inflow. Next, in step 56a, the gate 14a is closed as indicated by an imaginary line 14 'in FIG. 2 by a drive signal to the drive motor M14 of the exit gate 14a, and the sand basin 10a is separated from the other sand basins 10b and 10c. Sand collection by the low-pressure sand collection system is performed in a state where the inflow of sewage into the sand basin 10a is blocked and separated from the other sand basins 10b and 10c. That is, in step 58a, the sand pump 32 is driven, and initially, the sewage remains in the sand basin 10a although the water level is low, but the sewage in the sand basin 10a is discharged by the rotation of the sand pump 32 and the liquid level is raised. When the sand pump 32 is lowered slightly before the suction port 32-1 of the sand pump, the sand pump 32 is temporarily stopped. In step 60 a, a signal is sent from the control circuit 36 to drive the water supply pump 30, and water is injected from the watering nozzle 26. The water sprayed from the watering nozzle 26 flows down on the slope 22, and the sand settling on the slope 22 is collected in the sand collecting pit 20. The water pressure for water spraying from the nozzle 26 for sand collection is 0.3 MPa or less, more preferably 0.0002 to 0.005 MPa. Next, at step 62a, a signal is sent from the control circuit 36 to drive the sand pump 32 again, and the sand collected in the sand collecting pit 20 on the bottom surface of the sand basin 10a is sent to the ground (not shown) by the sand pump 32 together with sewage. Water is transported to the sedimentation facility, where the sediment is separated from the water, and the sediment is transported to the disposal site by truck. In step 64a, the gate is opened as shown by the solid line in FIG. 2 by the drive signal to the drive motor M12 of the inlet gate 12a, and the gate 14a is shown by the drive signal to the drive motor M14 of the exit gate 14a as shown by the solid line in FIG. Open. That is, it returns to the original state where both the inflow gate 12a and the exit gate 14a are opened, and the sewage from the sewage inflow pipe 8 flows again into the sand basin 10a. During the sand collection operation of the sand basin 10a as described above, the gates 12b, 12c, 14b, and 14c are left open in the remaining sand basins 10b and 10c, and drainage by the water flow and drain pump 18 is performed as usual. Yes.

When the sand settling process of the first sand settling basin 10a is completed in this way and the first sand settling basin 10a returns to the normal water flow state, the sand settling process in the second settling basin 10b is similarly performed in steps 54b to 64b. Done. That is, the inlet gate 12b is closed (step 54b), the outlet gate 14b is closed (step 56b), the sand basin 10b is emptied by the sand pump 32 (step 58b), and sand collection by water spraying from the nozzle 26 is collected. (Step 60b), and the sand pumping pump 32 transports the settling sand to the settling separator (Step 62b). When the sand collection process of the second settling basin 10b is completed in this way, the gates 12b and 14b are opened (Step 64b). ). When the second sand basin 10b returns to the normal water flow state, the sand settling process in the third sand basin 10c is similarly performed in steps 54c to 64c. That is, the inlet gate 12c is closed (step 54c), the outlet gate 14c is closed (step 56c), the sand basin 10c is emptied by the sand pump 32 (step 58c), and sand collection by water spray from the nozzle 26 is collected. (Step 60c), and the sand pumping pump 32 transports the settling sand to the settling separator (Step 62c). When the sand collection process of the third settling basin 10c is completed in this way, the gates 12c and 14c are opened (Step 64c). ).

  FIG. 5 shows a second embodiment of the present invention. In this embodiment, pump wells 16a, 16b, and 16c are individually provided downstream of three sand basins 10a, 10b, and 10c. That is, the pump wells 16a and 16b and the pump wells 16b and 16c are separated by the weirs 70 and 72 and are made independent. That is, there is no circulation between the pump wells 16a, 16b and 16c, and the pump wells 16a, 16b and 16c are provided with respective pumps 18a, 18b and 18c for drainage. The gates 14a, 14b, 14c on the outlet side of the sand basins 10a, 10b, 10c in the first embodiment shown in FIG. 1 are not installed in this second embodiment. The pumps 18a, 18b, 18c are provided with weirs 70, 72 between the pump wells 16a, 16b and between the pump wells 16b, 16c. It can be made to function as a separation means of the present invention which separates from a sewage settling basin.

  The operation of the second embodiment will be described. Normally, the entrance gates 12a, 12b, and 12c are opened, and sewage flows into the sand basins 10a, 10b, and 10c, and the sewage from the sand basins 10a, 10b, and 10c. Are sent to the next-stage sewage treatment facility such as a sedimentation basin by respective pumps 18a, 18b, 18c. Water flow through the sand basins 10a, 10b, and 10c is sequentially stopped at a predetermined time zone such as midnight when sand collection is performed, and the sand basins that have stopped water flow are emptied, and sand collection by a low pressure sand collection method is performed. That is, initially, the entrance gate 12a is closed for sand collection in the sand settling basin 10a, drainage is performed by the sand pump 32, and the sand settling basin 10a is emptied. Meanwhile, since the remaining gates 12b and 12c are open, the inflow of sewage into the sand basins 10b and 10c and the discharge of sewage by the pumps 18b and 18c are continued. In the state where the sand settling basin 10a is empty, the sand collecting operation of collecting sand in the sand collecting pit 20 by spraying water from the water spray nozzle and then sanding by driving the sand pump 32 is performed in the first embodiment. Done in the same way. After completion of sand collection in the sand basin 10a, the entrance gate 12a is opened again, and the inflow of sewage into the sand basin 10a is resumed. Next, the entrance gate 12b of the second settling basin 10b is closed, drainage by the sand pump 32 is performed, the settling basin 10b is emptied, and the settling into the sand collecting pit 20 by spraying water from the water spray nozzle After that, the sand collection by the low pressure sand collection method called sand collection is carried out in the sand settling basin 10b by driving the sand pump 32. During this time, the inflow of sewage into the sand basins 10a and 10c and the discharge of sewage by the pumps 18a and 18c are continued. When the sand collection by the low pressure sand collection method in the sand basin 10b is completed, finally, the entrance gate 12c of the third sand basin 10c is closed, the drainage pump 32 is drained, and the sand basin 10c is empty. Then, sand collection in the sand collection pit 20 is performed by spraying water from a water spray nozzle, and then sand collection is performed in the sand settling basin 10c by a low pressure sand collection method called sand removal by driving the sand pump 32. During this time, the inflow of sewage into the sand basins 10a and 10b and the discharge of sewage by the pumps 18a and 18b are continued. In this way, when the low-pressure sand collection method is completed in all the sand settling basins 10a, 10b, 10c, the sand collection work in this time zone is completed, and all the sand settling basins 10a, 10b, 10c are completed. It returns to the normal operation in which sewage flows in and is discharged by the pumps 18a, 18b, 18c.

FIG. 1 is a schematic plan view of a sewage settling basin according to the first embodiment of the present invention. FIG. 2 is a schematic longitudinal sectional view of one sewage settling basin (cross sectional view taken along the line II-II in FIG. 1). FIG. 3 is a schematic cross-sectional view (cross-sectional view taken along line III-III in FIG. 2) of one sewage settling basin. FIG. 4 is a flowchart for explaining an operation flow for sand collection in the first embodiment. FIG. 5 is a schematic plan view of a sewage settling basin according to the second embodiment of the present invention.

Explanation of symbols

8 ... Sewage inflow pipe
10 (10a, 10b, 10c) ... Sedimentation pond
12 (12a, 12b, 12c) ... Inflow gate
14 (14a, 14b, 14c) ... Outflow gate
16 (16a, 16b, 16c) ... Pump well
18 (18a, 18b, 18c) ... drainage pump 20 ... sand collecting pit 24 ... trough 26 ... sprinkling nozzle 28 ... water supply pipe 30 ... water supply pump 32 ... sand pump 34 ... sand pump 36 ... control circuit 38 ... timer
M12, M14 ... Gate drive motor

Claims (5)

  A sand collecting device in a sewer under constant water flow, which is provided in parallel with the direction of sewage flow, each of which forms a sand collecting pit on the bottom surface, and means for collecting and collecting sand by a water flow to the sand collecting pit. Multiple sedimentation basins equipped with means for discharging sewage and sedimentation from the sand pit, pump wells downstream of the sedimentation basins, drainage pumps located in the pump wells, and inflow of sewage into each sedimentation basin individually A sand collecting device comprising: an entrance gate for controlling opening and closing; and a separating means for separating a sand basin with the entrance gate closed from other sand basins.   A sand collecting device in a sewer under constant water flow, which is provided in parallel with the direction of sewage flow, each of which forms a sand collecting pit on the bottom surface, and means for collecting and collecting sand by a water flow to the sand collecting pit. Multiple sedimentation basins equipped with means for discharging sewage and sedimentation from the sand pit, common pump wells downstream of the multiple sedimentation basins, drainage pumps located in the pump wells, and inflow of sewage into each sedimentation basin A sand collecting device comprising an inlet gate for individually controlling opening and closing, and an outlet gate provided between each sand settling basin and the pump well.   A sand collecting device in a sewer under constant water flow, which is provided in parallel with the direction of sewage flow, each of which forms a sand collecting pit on the bottom surface, and means for collecting and collecting sand by a water flow to the sand collecting pit. Multiple sedimentation basins with means for discharging sewage and sedimentation from the sand pits, independent pump wells downstream of each sedimentation basin, drainage pumps located in each pump well, and inflow of sewage into each sedimentation basin A sand collecting device comprising an entrance gate for individually controlling opening and closing.   A method of collecting sand in sewers under constant water flow, which is provided in parallel with the direction of sewage flow and has multiple sand basins with sand collection pits on the bottom, and the inflow of sewage into each sand basin individually. In addition, each sedimentation basin is provided with an exit gate or a separate pump well to prevent the inflow of sewage individually. It can be separated from other sedimentation basins, and at low sewage volume, water flow to some of the sand basins is continued while water flow to the remaining sand basins The sedimentation basin is blocked and separated from the settling basin under water flow and drained. Accumulated in the sand collection pit with water flowing along the bottom, along with sewage Collecting sand method to be discharged by the sand pump.   5. The sand collection method according to claim 4, wherein the sand collection in the plurality of sand basins is sequentially performed in a specific time zone where the amount of water is low.

Images