JP4195867B2 - Method of suppressing hydrogen sulfide in pressure-type sewerage facilities and pressure-type sewerage facilities - Google Patents

Description

  The present invention relates to a pressure-feed sewerage facility such as a manhole pump station and a method for suppressing hydrogen sulfide in the facility.

  Conventionally, a pressure-type sewerage facility that pumps sewage using a pump or the like is known. In this type of sewerage facility, when sewage stays in the pumping pipe for a long time, anaerobization of the sewage proceeds and hydrogen sulfide is generated. However, hydrogen sulfide causes a bad odor. Further, when hydrogen sulfide is generated in the facility, sulfuric acid is generated from the hydrogen sulfide, which easily causes corrosion of the concrete.

  In view of this, various methods for suppressing the generation of hydrogen sulfide have been proposed in order to prevent malodor and prevent corrosion of concrete. As one of such hydrogen sulfide suppression methods, a method of preventing anaerobic wastewater by injecting an oxygen-containing gas into a pressure feeding pipe is known (for example, see Patent Document 1).

The sewerage facility disclosed in Patent Document 1 includes a sewage pump and an air injection compressor. In this sewerage facility, the anaerobic compressor and the sewage pressure pump are always operated in parallel, and air is supplied to the sewage being pumped to prevent anaerobic sewage in the pressure feed pipe. However, if only the air injection compressor and the sewage pressure pump are operated in parallel, and the operation stop state of the sewage pressure pump continues for a long time, the air injection compressor will also be stopped for a long time. Air will not be supplied to the sewage for a long time. Therefore, in the sewerage facility, when the operation stop state of the sewage pressure feeding pump continues for a predetermined time, the air injection compressor is driven alone to forcibly supply air into the pressure feeding pipe.
Japanese Patent Laid-Open No. 11-172756

  However, in a sewerage facility that injects air or oxygen into a pressure feeding pipe, additional equipment such as a compressor for injecting air or an oxygen generator is required. For this reason, there is a problem that the construction cost of the entire facility becomes high. In addition, the installation space for these additional facilities must be secured, which may increase the size of the facility.

  As described above, in the sewerage facility disclosed in Patent Document 1, when the operation stop state of the sewage pump is continued for a predetermined time, the air injection compressor is driven alone. However, since the sewage is stopped in the pumping pipe, the effect of air injection performed with the sewage pump being stopped is not sufficient. Therefore, the above-mentioned sewerage facilities cannot be expected to have a sufficient effect at a pumping station where the sewage pump is often stopped, that is, at a pumping station with a low pump operation rate.

  In addition, in the method of injecting air or oxygen into the pressure feed pipe, gas is inevitably mixed in the pressure feed pipe, which may increase the pressure loss in the pressure feed pipe. In particular, if there are many ascending slopes and descending slopes in the pressure feed pipe, the pressure loss tends to increase. Therefore, the load of the pump for pressure feeding becomes large, and there is a possibility that it is difficult to smoothly pump sewage. In addition, gas accumulates in a part of the pressure feeding pipe, and the so-called airlock phenomenon may hinder the smooth flow of sewage.

  The present invention has been made in view of such points, and the object of the present invention is to prevent the smooth flow of sewage in the pumping pipe without causing a significant increase in cost and size of the facility. It is to suppress the generation of hydrogen sulfide.

  A pressure-feed sewerage facility according to the present invention includes a water tank for storing sewage, a water level meter for detecting the level of sewage in the water tank, a pump for pumping sewage in the water tank, and a discharge side of the pump. A pressure feed pipe connected to discharge the sewage discharged from the pressure feed pump to the outside of the water tank, a return pipe branched from the pressure feed pipe and opened in the water tank, and an opening / closing to open and close the flow path of the return pipe A pressure-feed type sewerage facility having a mechanism and a control means for controlling the pressure-feed pump and the opening / closing mechanism, and the control means starts operation of the pressure-feed pump when the water level of the water tank becomes a predetermined water level or higher. A normal operation that opens, opens and closes the opening and closing mechanism, returns a part or all of the sewage in the pressure feeding pipe to the water tank through the return pipe, then closes the opening and closing mechanism, and then starts the operation of the pressure feeding pump water And it executes the suppression operation.

  According to the pumping sewerage facility, part or all of the sewage in the pumping pipe is once returned to the water tank during the hydrogen sulfide suppression operation. Therefore, even if the operation stop state of the pressure pump continues for a long time, by executing the hydrogen sulfide suppression operation, the sewage that has become anaerobic in the pressure supply pipe is returned to the water tank and comes into contact with the air. Then, the sewage whose dissolved oxygen concentration has increased due to contact with air is sent again to the pumping pipe by the pump. This prevents the sewage from becoming anaerobic and suppresses the generation of hydrogen sulfide.

  In the above-mentioned pressure feed type sewerage facility, an air injection compressor and an oxygen generator for injecting air into the pressure feed pipe are not required. Further, unlike the method in which air or oxygen is directly fed to the pressure feed pipe, there is no need to mix gas into the pressure feed pipe. Therefore, generation of hydrogen sulfide can be suppressed without causing an increase in pressure loss in the pumping pipe and an air lock phenomenon.

  Preferably, the control means includes a timer, and executes the hydrogen sulfide suppression operation when the water level of the water tank is lower than the predetermined water level after a predetermined time has elapsed since the operation stop of the pumping pump.

  As a result, when the water level reaches a predetermined water level before a predetermined time has elapsed since the operation stop of the pump, the normal operation is performed and the sewage is pumped to the pump. Accordingly, sewage is prevented from staying in the pressure feeding pipe. On the other hand, when the water level has not yet reached the predetermined water level after a predetermined time has elapsed since the operation stop of the pressure pump, the hydrogen sulfide suppression operation is executed without waiting for the water level to rise. Therefore, sewage is prevented from staying in the pressure feed pipe for a long time, and generation of hydrogen sulfide is suppressed.

A pressure feed pipe water quality detector that detects the quality of sewage in the pressure feed pipe may be provided, and the control means may perform the hydrogen sulfide suppression operation based on a detection result of the pressure feed pipe water quality detector.
Thereby, the hydrogen sulfide suppression operation can be executed based on the water quality state of the sewage in the pumping pipe. For example, the dissolved oxygen concentration of sewage in the pressure feeding pipe may be detected, and the hydrogen sulfide suppression operation may be executed when the dissolved oxygen concentration becomes a predetermined value or less. As a result, the generation of hydrogen sulfide is efficiently suppressed.

  The pressure-feed sewerage facility preferably includes an oxygen supply means for supplying an oxygen-containing gas to sewage in the water tank before the operation of the pressure-feed pump in the hydrogen sulfide suppression operation is started.

  Thus, during the hydrogen sulfide suppression operation, oxygen is supplied to the sewage returned from the pressure feed pipe, and the anaerobization of the sewage is further suppressed. Accordingly, hydrogen sulfide is more difficult to be generated.

  The oxygen supply means preferably comprises a self-priming aeration mixer.

  By providing an aeration mixer in this manner, anaerobic wastewater can be effectively suppressed. Moreover, sewage can be purified to some extent. Furthermore, since the aeration mixer is a self-priming type, it is not necessary to provide a device for supplying an oxygen-containing gas (for example, air or oxygen) in addition to the mixer, and the size and cost of the equipment can be suppressed. . Moreover, since the anaerobization countermeasure of sewage can be performed in a water tank, the enlargement of a facility can be suppressed.

  The pressure-feed type sewerage facility is installed in the water tank, and engages with the pressure-feed pump to guide the raising and lowering of the pressure-feed pump, and is fixed to the aeration mixer and engaged with the guide bar. And a guide member for guiding the raising and lowering of the aeration mixer.

  Accordingly, the aeration mixer can be easily and quickly installed by diverting the guide rod that guides the raising and lowering of the pressure pump. Therefore, the construction of the facility becomes easy. Moreover, the sewerage facility can be easily realized by newly installing an aeration mixer for the existing facility.

  The water level gauge is preferably fixed to the aeration mixer.

  Thus, although the sewage in the water tank is agitated with aeration, the water level meter is fixed to the aeration mixer, and thus the water level meter is prevented from swinging. Therefore, the water level is detected with high accuracy. Further, since the water level gauge can be raised and lowered as the aeration mixer is raised and lowered, the maintenance of the water level gauge becomes easy.

  A water tank water quality detector for detecting the quality of sewage in the water tank is provided, and the control means adjusts the operation time of the aeration mixer based on the detection result of the water tank water quality detector during the hydrogen sulfide suppression operation. It is preferable to do.

  Thus, the aeration mixer can be operated while checking the quality of the returned sewage. Therefore, the operation of the aeration mixer can be continued until the quality of sewage is reliably improved. For example, by detecting the dissolved oxygen concentration of the sewage in the water tank and operating the aeration mixer until the dissolved oxygen concentration exceeds a predetermined value, the anaerobization of the sewage can be reliably prevented. In addition, excessive operation of the aeration mixer is prevented, and operation efficiency is improved.

  In the hydrogen sulfide suppression operation, the control unit preferably starts the operation of the pressure pump after a predetermined time has elapsed since the aeration mixer was stopped.

  As a result, bubbles generated in the sewage due to aeration naturally disappear when a predetermined time elapses after the operation of the aeration mixer is stopped. Therefore, almost no bubbles are contained in the sewage transported from the pressure feed pump to the pressure feed pipe. As a result, the mixing of bubbles in the pressure feeding tube is suppressed, so that an increase in pressure loss of the pressure feeding tube and an air lock phenomenon are suppressed. Therefore, even if the pumping pipe has an upward slope or a downward slope, there is no possibility that the smooth flow of sewage is hindered.

  A bubble detector for detecting bubbles contained in the sewage in the water tank is provided, and the control means stops bubbles in the sewage in the water tank after the aeration mixer is stopped during the hydrogen sulfide suppression operation. It is preferable to start the operation of the pumping pump after the amount is below the fixed amount.

  As a result, mixing of bubbles into the pressure feed pipe is suppressed with high accuracy, and an increase in pressure loss and an air lock phenomenon in the pressure feed pipe are more reliably prevented.

  The water tank may be embedded in the ground, and the pressure-feed sewerage facility may constitute a manhole pump station.

  The manhole pumping station is a pumping station with a relatively small scale among pumping stations that transport sewage to other pumping stations or sewage treatment plants. In general, the manhole pumping station has a problem that there are many restrictions on the installation space of the facility and a large cost cannot be spent compared to the relay pumping station or the like. In general, the amount of inflow of sewage is relatively small and the pump operation rate is low. Furthermore, since it is buried in the ground, an ascending slope and a descending slope are likely to occur in the pumping pipe. Therefore, if the pressure-feed sewerage facility is applied to a manhole pump station, the above-described effects are remarkably exhibited.

  The method for suppressing hydrogen sulfide according to the present invention is a method for suppressing hydrogen sulfide in a pressure-feed sewer facility that pumps sewage stored in a water tank through a pressure-feed pipe, and returns a part or all of the sewage in the pressure-feed pipe to the water tank. The method includes an oxygen supply step of supplying an oxygen-containing gas to the sewage returned to the water tank, and a re-pumping step of pumping the sewage after the oxygen is supplied to the pumping pipe.

  According to the above method, the sewage that is becoming anaerobic in the pressure feeding pipe is once returned to the water tank. And oxygen is supplied to the sewage returned to the water tank. As a result, the sewage that has become anaerobic is aerobic. Then, the aerobic sewage is sent to the pressure feeding pipe again. In this way, anaerobic generation of sewage in the pumping pipe is prevented, and generation of hydrogen sulfide is suppressed.

  The method for suppressing hydrogen sulfide detects whether or not a predetermined time has elapsed since the sewage in the water tank was pumped to the pumping pipe and the water level of the water tank is lower than a predetermined water level before the returning step. A step may be provided, and the return step may be executed when a predetermined time has elapsed since the sewage was pumped to the pumping pipe and the water level of the water tank is lower than the predetermined water level.

  Thus, even when the amount of inflow of sewage is small and the water level does not rise above the predetermined water level, when the predetermined time has elapsed since the sewage was pumped to the pumping pipe, the return step, the oxygen supply step, and the A re-pumping process is performed. For this reason, the sewage is prevented from staying in the pumping pipe for a long time, and the generation of hydrogen sulfide is suppressed.

  Preferably, the method for suppressing hydrogen sulfide includes a step of detecting the quality of sewage in the pressure feed pipe before the return step, and the return step is executed based on the quality of sewage in the pressure feed pipe.

  As a result, the returning step, the oxygen supplying step, and the re-pressing step are performed based on the quality of the sewage in the pressure-feeding pipe, so that generation of hydrogen sulfide is efficiently suppressed.

  The oxygen supply step includes a step of aerating the sewage in the water tank by a self-priming aeration mixer, and the re-pressure feeding step is preferably executed after a predetermined time has elapsed from the oxygen supply step. .

  As a result, oxygen is efficiently supplied to the sewage, and aerobicization of the sewage is promoted. Moreover, sewage can be purified to some extent. Furthermore, since the aeration mixer is a self-priming type, it is not necessary to provide an air injection compressor or the like, and it is possible to suppress an increase in facility size and a significant increase in cost. In addition, since the re-pumping process is not performed immediately after the oxygen supply process is completed, but the re-pumping process is performed after a lapse of a predetermined time from the oxygen supply process, the sewage remains in a state where bubbles are mixed in the sewage in the water tank. It can prevent being conveyed to a pressure feeding pipe. Therefore, it is possible to suppress bubbles from being mixed into the pressure feeding pipe, and it is possible to prevent an increase in pressure loss and an air lock phenomenon in the pressure feeding pipe.

  The oxygen supply step comprises a step of aerating the sewage in the water tank by a self-priming aeration mixer, and after the oxygen supply step, the step of detecting bubbles contained in the sewage in the water tank, It is preferable that the re-pressing step is executed after the amount of bubbles contained in the sewage in the water tank becomes a predetermined amount or less.

  As a result, the sewage is suppressed from being conveyed to the pressure feed pipe while the bubbles are mixed in the sewage in the water tank. Therefore, it is possible to prevent an increase in pressure loss and an air lock phenomenon in the pressure feeding pipe.

  According to the present invention, part or all of the sewage in the pumping pipe is once returned to the water tank, and the sewage is brought into contact with air and then pumped again to the pumping pipe. In addition, without causing an increase in pressure loss in the pressure feed pipe and without causing an air lock phenomenon, anaerobic sewage in the pressure feed pipe can be prevented and generation of hydrogen sulfide can be suppressed.

  When the water level in the tank reaches or exceeds the predetermined water level, normal operation is performed.On the other hand, if the water level is lower than the predetermined water level even after a predetermined time has elapsed since the stoppage of the pump, the hydrogen sulfide suppression operation is performed. , Generation of hydrogen sulfide can be suppressed.

  If the hydrogen sulfide suppression operation is performed based on the quality of the sewage in the pumping pipe, the hydrogen sulfide suppression operation can be performed at a more appropriate time, and hydrogen sulfide can be efficiently suppressed.

  If oxygen supply means for supplying oxygen-containing gas to the sewage in the water tank is provided, oxygen can be efficiently supplied to the sewage returned to the water tank, and generation of hydrogen sulfide can be more reliably suppressed. it can.

  If a self-priming aeration mixer is provided as the oxygen supply means, sewage can be aerobic, and in addition to suppressing hydrogen sulfide, sewage can be purified. In addition, since the aeration mixer is self-priming, it is not necessary to provide dedicated oxygen supply means (air injection compressor, etc.) etc. outside the water tank, and the cost and size of the facility are suppressed accordingly. be able to.

  If the aeration mixer is provided with a guide member that engages with a guide rod that guides the raising and lowering of the pump, the installation of the aeration mixer can be facilitated. In addition, the aeration mixer can be easily installed in an existing facility.

  If the water level meter is fixed to the aeration mixer, unlike the case where the water level meter is suspended and installed, the water level meter can be prevented from swinging due to the agitation of sewage. Therefore, the water level can be detected with high accuracy.

  If the operation time of the aeration mixer is adjusted based on the detection result of the quality of the sewage in the aquarium, the generation of hydrogen sulfide can be more reliably suppressed and the excessive operation of the aeration mixer can be prevented. Can be made more efficient.

  In the hydrogen sulfide suppression operation, if the operation of the pressure pump is started after a lapse of a predetermined time after the operation of the aeration mixer is stopped, it is possible to more reliably suppress bubbles from being mixed into the pressure tube. . Therefore, an increase in pressure loss and an air lock phenomenon in the pressure feeding pipe can be further suppressed.

  In the hydrogen sulfide suppression operation, if the operation of the pumping pump is started after the amount of bubbles contained in the sewage in the water tank falls below a predetermined amount, it is more reliably suppressed that bubbles are mixed into the pumping tube. Therefore, an increase in pressure loss and an air lock phenomenon in the pressure feeding pipe can be further suppressed.

  If the pressure-feed type sewerage facility according to the present invention is applied to a manhole pump station, the above effects can be exhibited more remarkably.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the pressure-type sewerage facility according to the embodiment is a manhole pump station 1 embedded in the ground 5. The manhole pump station 1 includes a pump well 10 as a water tank for storing sewage, a submersible pump 11 and an aeration mixer 12 installed inside the pump well 10. In this embodiment, two submersible pumps 11 are provided. However, the number of submersible pumps 11 is not limited at all.

  An inflow pipe 14 that guides sewage to the inside of the pump well 10 is disposed at the side of the pump well 10. In addition, a pumping pipe 13 for conveying sewage to the outside is disposed in the pump well 10 so as to penetrate inside and outside of the pump well 10.

  An air vent valve 9 for discharging air contained in the discharged water is attached to the discharge pipe 15 of each submersible pump 11. A check valve 16 and an on-off valve 17 are sequentially connected to the tip of each discharge pipe 15. The root side of the pressure feed pipe 13 is branched into three branch pipes, and the open / close valves 17 of both discharge pipes 15 are connected to the two branch pipes of the pressure feed pipe 13 respectively. Thereby, the sewage discharged from both submersible pumps 11 merges in the pressure feed pipe 13 and is discharged to the outside of the pump well 10 through the pressure feed pipe 13. The pressure feed pipe 13 extends from the side of the pump well 10 to the outside and is connected to another manhole pump station or a water treatment facility (not shown).

  A return pipe 18 for returning the sewage in the pressure feed pipe 13 is connected to the other branch pipe of the pressure feed pipe 13. The return pipe 18 opens downward in the pump well 10. That is, the return pipe 18 is opened inside the pump well 10. The return pipe 18 is provided with an open / close valve 19. The on-off valve 19 is composed of an electromagnetic valve, for example, and is controlled to be opened / closed by the controller 20. The on-off valve 19 is normally closed.

  The controller 20 is provided on a control panel (not shown) installed on the ground, and includes a timer 37. The controller 20 performs ON / OFF control of the submersible pump 11 and ON / OFF control of the aeration mixer 12 in addition to the control of the on-off valve 19. In addition, various sensors such as a water level gauge 30 described later are connected to the controller 20.

  As shown in FIGS. 2 and 3, a pair of guide rods 21 extending in the vertical direction are installed inside the pump well 10. The guide rod 21 may be fixed to the side wall of the pump well 10 via a support member or the like, or may be fixed to the bottom surface. In this embodiment, both guide rods 21 are each formed in a columnar shape and are arranged in parallel to each other. However, the cross-sectional shape of the guide bar 21 is not limited to a circular shape, and may be a rectangular shape or an elliptical shape. The shape of the guide bar 21 is not limited at all. The guide rod 21 may not be a solid rod-shaped body, but may be a hollow rod-shaped body (guide pipe). Further, the number of guide bars 21 is not limited at all. In the present embodiment, a pair of guide rods 21 is installed for each submersible pump 11. Therefore, although not shown, a total of four guide rods 21 are installed in the manhole pump station 1.

  As shown in FIG. 3, a guide member 22 that engages with both guide rods 21 is attached to the submersible pump 11. The guide member 22 is composed of a substantially block body in which a semicircular recess corresponding to the shape and size of each guide bar 21 is formed on both sides. Therefore, when the submersible pump 11 is moved up and down while the guide members 22 are engaged with the two guide rods 21, the guide member 22 slides in the longitudinal direction (that is, the vertical direction) of the two guide rods 21. As a result, the submersible pump 11 is guided to the guide rod 21 and stably moves up and down without swinging back and forth and left and right. Since the guide member 22 and the guide rod 21 guide the vertical movement of the submersible pump 11 as described above, the submersible pump 11 is installed at a predetermined position by a simple operation of hanging the submersible pump 11 with the chain 23 or the like. can do.

  As shown in FIGS. 2 and 4, the aeration mixer 12 includes a submersible motor 24, an impeller 25 fixed to the rotating shaft of the submersible motor 24, and a casing 26 that covers the outer periphery of the impeller 25. The aeration mixer 12 is a self-priming aeration mixer that sucks air by the rotation of the impeller 25, and includes an intake pipe 27 for sucking air.

  The intake pipe 27 is formed of a rigid pipe, and here is formed of stainless steel. However, the material of the intake pipe 27 is not particularly limited, and other materials may be used. For example, the weight of the aeration mixer 12 may be reduced by forming the intake pipe 27 with vinyl chloride. As shown in FIG. 2, the intake pipe 27 extends substantially in the vertical direction, and a flange 28 is provided at the upper end thereof. The lower end of the intake pipe 27 opens to the suction side of the impeller 25, and constitutes an aeration nozzle that blows out air. A flexible tube 29 having flexibility is connected to the flange 28 of the intake pipe 27. Although illustration is omitted, the upper end of the flexible tube 29 opens at a position above the surface of the sewage.

  A water level gauge 30 is fixed to the intake pipe 27. The water level gauge 30 is a so-called pressure-type water level gauge that detects the water level based on the water pressure. However, the type of the water level gauge 30 is not particularly limited. In the present embodiment, the water level gauge 30 is fixed to the intake pipe 27 by a binding band 31 together with the motor cable 32. However, the fixing method of the water level gauge 30 is not limited at all as long as the water level gauge 30 can be stably fixed. In FIG. 2, the binding band 31 is exaggerated, but actually, the binding band 31 is tightly fixed to the intake pipe 27 and the like. The signal line 34 of the water level gauge 30 and the motor cable 32 of the submersible motor 24 are also fixed to the flexible tube 29 by a binding band 31. Therefore, the signal line 34, the motor cable 32, and the flexible tube 29 are bundled together.

  As shown in FIG. 4, the aeration mixer 12 is also provided with a guide member 35 that is substantially the same as the guide member 22 of the submersible pump 11. That is, the guide member 35 of the aeration mixer 12 is also composed of a substantially block body in which semicircular recesses 36 corresponding to the shape and dimensions of the guide bar 21 are formed on both sides.

  Therefore, the elevation of the aeration mixer 12 can be guided by engaging the guide members 35 with the guide rods 21 and sliding the guide members 35 with respect to the guide rods 21. Therefore, according to the present embodiment, the existing guide rod 21 for guiding the submersible pump 11 can be used to guide the raising and lowering of the aeration mixer 12. In addition, since the aeration mixer 12 of this embodiment is a small and lightweight mixer, even if it does not use lifting devices, such as a crane, by pulling the chain 33 (refer FIG. 2) attached to the aeration mixer 12, people's The aeration mixer 12 can be lifted from the pump well 10 only by force. Further, the aeration mixer 12 can be easily installed at a predetermined position in the pump well 10 by being suspended by the chain 33.

  The aeration mixer 12 is suspended and supported by a chain 33. Therefore, the installation height of the aeration mixer 12 can be easily adjusted by adjusting the length of the chain 33. Although the aeration mixer 12 is suspended from the chain 33 and installed, the guide member 35 is engaged with the two guide bars 21. Is prevented by. Therefore, the aeration mixer 12 is prevented from swinging.

  The above is the configuration of the manhole pumping station 1. Next, operation control of the manhole pump station 1 will be described.

  The operation of the manhole pumping station 1 is controlled by the controller 20. In addition to the normal operation described below, the controller 20 executes a hydrogen sulfide suppression operation for suppressing the generation of hydrogen sulfide.

  The normal operation is an operation that starts pumping of sewage when the amount of sewage stored in the pump well 10 exceeds a certain amount. Specifically, the controller 20 receives a detection signal from the water level gauge 30 constantly or intermittently, and detects the water level of the pump well 10. Then, the controller 20 starts the operation of the submersible pump 11 when the water level reaches a predetermined water level (hereinafter referred to as an operation start water level). When the submersible pump 11 is operated, the sewage in the pump well 10 is sent from the discharge pipe 15 to the pressure feed pipe 13 and is discharged to the outside of the pump well 10 through the pressure feed pipe 13. As a result, the water level of the pump well 10 gradually decreases. The controller 20 stops the operation of the submersible pump 11 when the water level of the pump well 10 is equal to or lower than a predetermined lower limit water level (hereinafter referred to as a pump stop water level). Note that the water level being equal to or lower than the pump stop water level may be detected directly by the water level gauge 30 or may be detected by estimation based on the operation duration time of the submersible pump 11.

  By the way, in the normal operation, unless the water level reaches the operation start water level, the operation of the submersible pump 11 is not started, and the sewage is not pumped. However, if sewage continues to stay in the pumping tube 13 for a long time, hydrogen sulfide is likely to be generated in the pumping tube 13. In particular, in a small-scale sewerage facility such as a manhole pump station, since the amount of sewage inflow is small, the water level often does not rise to the operation start water level for a long time. Therefore, in this manhole pump station 1, when the operation stop state of the submersible pump 11 continues for a long time, the following hydrogen sulfide suppression operation is executed to suppress the generation of hydrogen sulfide.

  In the hydrogen sulfide suppression operation, first, the on-off valve 19 of the return pipe 18 is opened. As a result, the sewage that is becoming anaerobic in the pressure feed pipe 13 flows into the pump well 10. In addition, due to the nature of the manhole pumping station 1, the sewage flows into the pump well 10 by natural flow. Therefore, when returning the sewage in the pressure feed pipe 13, a drive source such as a pump is unnecessary.

  By returning such sewage, the water level of the pump well 10 rises and eventually reaches the operation start water level. When the water level reaches the operation start water level, the controller 20 closes the on-off valve 19 and starts the operation of the aeration mixer 12.

  When the operation of the aeration mixer 12 is started, air is injected into the sewage of the pump well 10. As a result, the dissolved oxygen concentration of sewage increases and anaerobic formation is prevented. Further, since the sewage is agitated by the aeration mixer 12, unlike the case of simply injecting air, the dissolution of oxygen in the sewage is promoted. In addition, the sewage is purified to some extent inside the pump well 10.

  The controller 20 stops the operation after operating the aeration mixer 12 for a predetermined time. By the way, immediately after the operation of the aeration mixer 12 is stopped, the sewage in the pump well 10 contains a large number of bubbles. Therefore, if the submersible pump 11 is started in that state, bubbles may flow into the pressure feed pipe 13 together with the sewage. However, the bubbles in the pressure feeding tube 13 are not preferable because they cause a pressure loss and may cause an air lock phenomenon. Therefore, in this embodiment, after the operation of the aeration mixer 12 is stopped, the operation of the submersible pump 11 is started after waiting for a predetermined time. As a result, sewage containing a large amount of dissolved oxygen and containing almost no bubbles is pumped to the pumping tube 13. The operation of the submersible pump 11 is performed until the water level reaches the pump stop water level.

  Next, the overall flow of the operation control combining the normal operation and the hydrogen sulfide suppression operation will be described with reference to the flowchart of FIG. 5 and the time chart of FIG. However, in this example, the aeration mixer 12 is operated even during normal operation, and the sewage in the pump well 10 is aerobically treated.

  In the present operation control example, first, in step S1, the controller 20 determines whether or not the current water level of the pump well 10 is equal to or higher than the operation start water level. Then, when it is determined that the water level is lower than the operation start water level (when the determination result of step S1 is NO), the process proceeds to step S2, and it is determined whether or not a predetermined time T1 has elapsed since the operation of the submersible pump 11 was stopped. If the determination result of step S2 is YES, the process proceeds to step S3, and the hydrogen sulfide suppression operation is started. On the other hand, if the decision result in the step S2 is NO, the process returns to the step S1 again.

  In step S3, the opening / closing valve 19 of the return pipe 18 is opened (see time B in FIG. 6). As a result, the sewage in the pressure feed pipe 13 is returned to the pump well 10. After opening the on-off valve 19, the process proceeds to step S4 to determine whether the water level is equal to or higher than the operation start water level. When the water level is lower than the operation start water level, the open / close valve 19 is kept open to further return the sewage in the pressure feed pipe 13. On the other hand, if the decision result in the step S4 is YES, the process advances to a step S5 to close the on-off valve 19 of the return pipe 18 and the return of sewage is ended (see time C in FIG. 6).

  When the determination result in step S1 is YES or after the on-off valve 19 is closed in step S5, the process proceeds to step S6, and the operation of the aeration mixer 12 is started (see time C in FIG. 6). After starting the operation of the aeration mixer 12, it is determined in step S7 whether or not a predetermined time T2 has elapsed since the start of the operation of the aeration mixer 12. If it is determined that the predetermined time T2 has elapsed, the process proceeds to step S8, and the operation of the aeration mixer 12 is stopped (see time D in FIG. 6).

  Next, it progresses to step S9 and it is determined whether predetermined time T3 has passed since the operation stop of the aeration mixer 12. FIG. If it is determined that the predetermined time T3 has elapsed, the process proceeds to step S10, and the operation of the submersible pump 11 is started (see time E in FIG. 6). That is, re-pumping of sewage is started. The predetermined time T3 is set to a time sufficient for the bubbles contained in the sewage after aeration to disappear.

  The water level of the pump well 10 decreases with the pumping of sewage. In step S11, it is determined whether the water level is equal to or lower than the pump stop water level. And if it judges that a water level is below a pump stop water level, it will progress to Step S12 and will stop operation of submersible pump 11 (refer to time F of Drawing 6).

  When the operation of the submersible pump 11 is stopped, the controller 20 resets the timer 37 and executes the processes after step S1 again. The operation control of the manhole pump station 1 in the present embodiment is performed as described above.

  As described above, according to the manhole pump station, in addition to the normal operation, when the submersible pump 11 has been stopped for a long time, the hydrogen sulfide suppression operation is executed, so that the generation of hydrogen sulfide is suppressed. can do. Therefore, even in a sewerage facility with a low pump operation rate, it is possible to prevent the generation of malodor and corrosion of concrete in the facility.

  In the hydrogen sulfide suppression operation, the sewage in the pressure feed pipe 13 is once returned to the pump well 10 and supplied with oxygen and then pumped again. Therefore, unlike the method in which air or oxygen is directly injected into the pressure feed pipe 13. The gas can be prevented from flowing into the pressure feeding tube 13. Therefore, even when the pressure feed pipe 13 has many ascending and descending slopes, an increase in pressure loss in the pressure feed pipe 13 can be suppressed, and an air lock phenomenon can be prevented. Therefore, the smooth flow of sewage in the pressure feeding pipe is not hindered.

  In the hydrogen sulfide suppression operation, the sewage in the pressure feed pipe 13 is returned by natural flow, so that a special drive source for returning the sewage is unnecessary. Further, the sewage in the pressure feed pipe 13 can be easily returned by a simple configuration in which the return pipe 18 is branched from the pressure feed pipe 13 and the opening / closing valve 19 is provided in the return pipe 18. Therefore, it is possible to suppress an increase in the size and cost of facilities associated with hydrogen sulfide countermeasures.

  Since the self-priming aeration mixer 12 installed inside the pump well 10 is used as the oxygen supply means, it is necessary to install additional equipment such as an air injection compressor and an oxygen generator outside the pump well 10. Absent. Therefore, a space (such as a building) for installing additional equipment is unnecessary, and the facility can be prevented from increasing in size and cost. Therefore, even though it is a manhole pumping station with limited space and cost, effective hydrogen sulfide countermeasures can be taken.

  Since oxygen is supplied to the sewage of the pump well 10 by the aeration mixer 12, the dissolved oxygen concentration of the sewage can be efficiently increased in combination with the original stirring effect of the mixer. Further, the sewage can be purified to some extent inside the pump well 10.

  Since the operation of the submersible pump 11 is started after a predetermined time has elapsed from the end of the operation of the aeration mixer 12, it is possible to effectively suppress bubbles from flowing into the pressure feed pipe 13. For this reason, it is possible to more reliably prevent an increase in pressure loss or the occurrence of an air lock phenomenon due to air bubbles mixed into the pressure feeding tube 13.

  Since the guide member 35 is provided in the aeration mixer 12 and the guide rod 21 for guiding the raising and lowering of the submersible pump 11 is used when the aeration mixer 12 is raised and lowered, the aeration mixer can be provided without newly providing a special lifting device. 12 can be installed easily.

  Since the water level gauge 30 for detecting the water level of the pump well 10 is fixed to the aeration mixer 12, the water level gauge 30 can be prevented from swinging. Therefore, the water level can be detected accurately. Further, by pulling up the aeration mixer 12 along the guide rod 21, the water level gauge 30 can also be pulled up easily. Therefore, maintenance of the water level gauge 30 is facilitated.

  By the way, in the said embodiment, hydrogen sulfide suppression driving | operation was performed when predetermined time T1 passed since the driving | operation stop of the submersible pump 11. FIG. That is, the operation start condition of the hydrogen sulfide suppression operation was based on the elapsed time. However, the parameter of the operation start condition for the hydrogen sulfide suppression operation is not limited to the elapsed time.

  For example, the hydrogen sulfide suppression operation may be started based on the quality of sewage in the pressure feed pipe 13. As shown in FIG. 7, a water quality sensor 40 may be provided in the pressure feed pipe 13 and the hydrogen sulfide suppression operation may be started when the quality of sewage satisfies a predetermined condition. For example, a DO meter may be used as the water quality sensor 40, and the hydrogen sulfide suppression operation may be started when the dissolved oxygen concentration of sewage falls below a predetermined value. In addition, in order to make installation easy, it is preferable to attach the water quality sensor 40 to the pressure feeding pipe 13 located inside the pump well 10.

  In the above embodiment, the aeration mixer 12 is set to operate only for a predetermined time T2. However, the operation time of the aeration mixer 12 may be adjusted according to the quality of sewage in the pump well 10. For example, as shown in FIG. 8, a water quality sensor 41 may be provided in the pump well 10 and the water quality (for example, dissolved oxygen concentration) may be detected by the water quality sensor 41. In this case, when the water quality of the sewage satisfies a predetermined condition (for example, a condition that the dissolved oxygen concentration is equal to or higher than a predetermined value), the operation of the aeration mixer 12 is stopped. As a result, excessive or insufficient operation of the aeration mixer 12 can be prevented, and the operation efficiency can be improved. The installation location of the water quality sensor 41 is not particularly limited, but is attached to the aeration mixer 12 (particularly the intake pipe 27) so that it can be easily installed in an existing pump station and from the viewpoint of preventing vibration. Is preferred.

  Further, in the above-described embodiment, the interval of the predetermined time T <b> 3 is provided between the stop of the operation of the aeration mixer 12 and the start of the operation of the submersible pump 11 so that the bubbles are not sent to the pressure feeding pipe 13. In other words, the operation start condition of the submersible pump 11 was based on the elapsed time from when the aeration mixer 12 was stopped. However, the bubbles contained in the sewage may be detected directly or indirectly, and the operation of the submersible pump 11 may be started based on the detection result. For example, although not shown, a turbidity sensor may be provided as a bubble detector in the pump well 10 and the bubbles in the sewage may be detected by the turbidity sensor. In this case, after the operation of the aeration mixer 12 is stopped, the operation of the submersible pump 11 is started when the turbidity of the sewage falls below a predetermined value. As a result, it is possible to more reliably prevent bubbles from entering the pressure feeding tube 13.

  The said embodiment was the form which applied the pressure-feed type sewerage facility which concerns on this invention to the manhole pumping station. However, the application target of the present invention is not limited to the manhole pumping station. It is of course possible to apply the pressure-feed type sewerage facility according to the present invention to a relay pump station or other sewerage facilities.

  As described above, the present invention is useful for pressure-feed sewer facilities such as manhole pump stations and relay pump stations.

It is a whole lineblock diagram of a manhole pump station concerning an embodiment. It is a figure which shows the installation state of a submersible pump and an aeration mixer. It is a top view of a submersible pump. It is a top view of an aeration mixer. It is a flowchart of operation control of a manhole pumping station. (A) And (b) is a time chart of the operation control of a manhole pump station. It is a whole block diagram of the manhole pump station which concerns on a modification. It is a whole block diagram of the manhole pump station which concerns on another modification.

Explanation of symbols

1 Manhole pumping station (pressure-feeding sewerage facility)
5 Ground 10 Pump well (water tank)
11 Submersible pump (pressure feed pump)
12 aeration mixer 13 pressure feed pipe 14 inflow pipe 15 discharge pipe 18 return pipe 19 on-off valve (open / close mechanism)
20 controller (control means)
21 Guide rod 27 Intake pipe 30 Water level gauge 31 Binding band 32 Motor cable 33 Chain 35 Guide member 37 Timer 40 Water quality sensor (pressure feed pipe water quality detector)
41 Water quality sensor (aquarium water quality detector)

Claims (16)

A tank for storing sewage,
A water level meter for detecting the level of sewage in the water tank;
A pump for pumping the sewage in the water tank;
A pressure feed pipe connected to the discharge side of the pressure feed pump, for discharging the sewage discharged from the pressure feed pump to the outside of the water tank;
A return pipe branched from the pressure feed pipe and opened in the water tank;
An opening and closing mechanism for opening and closing the flow path of the return pipe;
Control means for controlling the pump and the opening / closing mechanism;
A pressure-feed sewerage facility,
The control means includes a normal operation for starting the operation of the pumping pump when the water level of the water tank becomes a predetermined water level or more, and opening or closing the opening / closing mechanism to pass a part or all of the sewage in the pumping pipe through the return pipe A pressure-feed type sewerage facility that closes the opening / closing mechanism after returning to the state and then performs a hydrogen sulfide suppression operation that starts operation of the pressure-feed pump.   The said control means is provided with a timer, and when the water level of the said water tank is lower than the said predetermined water level after progress for a predetermined time from the time of the operation stop of the said pressure feeding pump, the said pressure | voltage feed type sewer of Claim 1 is performed. Facilities. A pressure feed pipe water quality detector for detecting the quality of sewage in the pressure feed pipe;
The said control means is a pressure-feed type sewer facility according to claim 1, wherein the hydrogen sulfide suppression operation is executed based on a detection result of the pressure-feed pipe water quality detector.   The pumping-type sewerage facility according to any one of claims 1 to 3, further comprising an oxygen supply means for supplying an oxygen-containing gas to the sewage in the water tank before the operation of the pumping pump in the hydrogen sulfide suppression operation is started. .   The pressure-feeding sewerage facility according to claim 4, wherein the oxygen supply means is a self-priming aeration mixer. A guide rod which is installed in the water tank and engages with the pressure feed pump to guide the elevation of the pressure feed pump;
A guide member which is fixed to the aeration mixer and guides the raising and lowering of the aeration mixer by engaging with the guide rod;
The pressure-feed type sewerage facility according to claim 5.   The said water level meter is a pressure-feed-type sewer facility of Claim 5 or 6 currently fixed to the said aeration mixer. A water tank water quality detector for detecting the quality of sewage in the water tank,
The said control means adjusts the operation time of the said aeration mixer based on the detection result of the said tank water quality detector in the case of the said hydrogen sulfide suppression operation, The pressure-feed type sewer as described in any one of Claims 5-7. Facilities.   The said control means starts the operation | movement of the said pressure feed pump after the predetermined time progress, after stopping the aeration mixer in the case of the said hydrogen sulfide suppression operation, The pressure-feed type sewer as described in any one of Claims 5-8. Facilities. A bubble detector for detecting bubbles contained in the sewage in the water tank,
The control means starts the operation of the pumping pump after the aeration mixer is stopped during the hydrogen sulfide suppression operation and then the bubbles contained in the sewage in the water tank become a predetermined amount or less. The pressure-feed type sewerage facility according to any one of 8 above.   The said water tank is embed | buried in the ground and comprises the manhole pumping station, The pressure-feed type sewer facility as described in any one of Claims 1-10. A method for suppressing hydrogen sulfide in a pressure-type sewerage facility that pumps wastewater stored in a water tank through a pressure-feed pipe,
A returning step of returning a part or all of the sewage in the pumping pipe to the water tank;
An oxygen supply step of supplying an oxygen-containing gas to the sewage returned to the water tank;
A re-pumping step of pumping the sewage after oxygen is supplied again to the pumping pipe;
A method for suppressing hydrogen sulfide. Before the returning step, comprising the step of detecting whether or not a predetermined time has passed since the sewage in the water tank was pumped to the pumping pipe and whether the water level of the water tank is lower than a predetermined water level,
The method for suppressing hydrogen sulfide according to claim 12, wherein the returning step is executed when a predetermined time has elapsed since the sewage was pumped to the pumping pipe and the water level of the water tank is lower than the predetermined water level. Before the returning step, comprising a step of detecting the quality of sewage in the pressure feeding pipe,
The method for suppressing hydrogen sulfide according to claim 12, wherein the returning step is executed based on a quality of sewage in the pressure feeding pipe. The oxygen supply step comprises a step of aerating the sewage in the aquarium with a self-priming aeration mixer,
The method for suppressing hydrogen sulfide according to any one of claims 12 to 14, wherein the re-pressure feeding step is executed after a predetermined time has elapsed from the oxygen supply step. The oxygen supply step comprises a step of aerating the sewage in the aquarium with a self-priming aeration mixer,
After the oxygen supply step, comprising a step of detecting bubbles contained in sewage in the water tank,
The method for suppressing hydrogen sulfide according to any one of claims 12 to 14, wherein the re-pressure feeding step is executed after the amount of air bubbles contained in the sewage in the water tank becomes a predetermined amount or less.

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