JP4584887B2 - Sludge scraping device - Google Patents

Description

  The present invention relates to a sludge scraping device for removing sludge accumulated on the bottom of a tank and scum on the water surface.

Conventionally, as a sludge scraping device, a sludge scraping blade that scrapes the sludge accumulated on the bottom by circulating movement in a tank, and a cam that can be reciprocated as the sludge scraping blade moves is provided. A sludge scraping device that removes scum on the water surface by transmitting and closing the cam movement to scum attracting / stopping means installed on the pond is known (for example, Patent Document 1).
JP 2000-84549 A

  Here, the amount of scum on the water surface is likely to change depending on the time, and it is necessary to adjust the swallowing amount according to the amount. However, in the sludge scraping device, the amount of scum swallowed is uniquely fixed by the structure of the sludge scraping blade, the scum attracting / stopping means, and the cam, so that the amount of scum swallowing can be changed. I can't. Therefore, there is a problem that the mechanism itself must be replaced in order to adjust the swallowing amount.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a sludge scraping device capable of easily adjusting the swallowing amount in accordance with the amount of scum on the water surface.

According to the sludge scraping device according to the present invention, a scraping base that reciprocates in the longitudinal direction of the tank in the tank, and a plurality of sludge scrapes that are supported by the scraping base and scrape the sludge accumulated on the bottom of the tank. The scum has an opening for sucking the scum that floats on the surface of the treated water contained in the tank, and is laid across the tank in the short direction of the tank at the height of the water surface. e Bei and Sukamupaipu rotatably supported to infested to water, and a power conversion mechanism for converting the reciprocating motion of the raking frame to the rotation of Sukamupaipu, a power conversion mechanism is rotatable at one end The lift bar pivotally supported on the lift bar, the reciprocating motion integrally with the cradle and the lower surface of the lift bar, the lift pin rotating the lift bar, one end connected to the other end of the lift bar, the other end Connected to the scum pipe, according to the rotation of the lift bar A link mechanism that links the two so as to rotate the scum pipe, and the lift pin is provided at a position that is not locked to the lift bar at the normal retreat limit position of the stroking base, The lift pin is locked to the lift bar when retracted from the limit position .

  According to this sludge scraping device, the scum pipe can be efficiently rotated without introducing a power source only for rotating the scum pipe by using the reciprocating motion of the scraping base for moving the sludge scraping blade. Can be made. Further, since the cradle and the scum pipe are linked by the power conversion mechanism, the swallowing amount of the scum pipe can be changed by changing the movement of the cradle. This makes it possible to easily adjust the swallowing amount in accordance with the amount of scum on the water surface.

  In the sludge scraping device according to the present invention, the power conversion mechanism reciprocates integrally with the lift bar pivotally supported at one end and the scraping base, and is engaged with the lower surface of the lift bar. A lift pin that rotates, and a link mechanism that has one end connected to the other end of the lift bar and the other end connected to the scum pipe, and links the two so as to rotate the scum pipe according to the rotation of the lift bar. It is preferable to have.

  According to this sludge scraping device, when the lift pin moves in the direction of the lift bar with the movement of the scraping base, the lift bar is engaged with the lower surface of the lift bar and pushed up, thereby rotating the lift bar about one end side as an axis. When the rotation is transmitted to the scum pipe via the link mechanism, the scum pipe also rotates, and the opening portion that has been exposed on the water surface is submerged in the water and sucks the scum. Also, when the lift pin moves in the opposite direction along with the scraper, the lift bar lifted returns to its original position by its own weight, and in conjunction with this, the scum pipe opening also comes out of the water surface and the scum suction is interrupted. . With such a configuration, it is possible to efficiently rotate the scum pipe without introducing a power source only for rotating the scum pipe by using the reciprocating operation of the scraper for moving the sludge scraping blade. it can. Moreover, the swallowing amount of the scum pipe can be changed by adjusting the stop time of the scraping table and the stroke of the reciprocating motion of the lift pins to change the lift height and time of the lift bar. This makes it possible to easily adjust the swallowing amount in accordance with the amount of scum on the water surface.

  In the sludge scraping device according to the present invention, the link mechanism includes a scum bar that rotates integrally with the scum pipe, one end pivotally supported by the other end of the lift bar, the other end pivotally supported by the scum bar, and extending in the vertical direction. According to this, when the lift bar is pushed up, the scum pipe rotates through the lift shaft and the scum bar to swallow the scum, so that the scum can be reliably removed with a simple structure. It can be carried out.

  In the sludge scraping device according to the present invention, the lift pin is provided at a position not locked to the lift bar at the normal retract limit position of the scraper base, and when the scraper base is retracted from the normal retract limit position, the lift pin It is preferable to be locked to the lift bar. According to this, normally, the sludge is squeezed without sucking the scum, and the scraper is moved backward from the normal retreat limit position only when necessary to suck the scum. Therefore, the amount of scum swallowed can be adjusted more easily.

  In the sludge scraping device according to the present invention, it is preferable that the scraper base is moved backward from the normal retreat limit position every predetermined number of reciprocations of the scraper base. The scum swallowing amount can be easily adjusted simply by adjusting the number of times of retreating from the retreat limit position.

  In the sludge scraping device according to the present invention, the sludge scraping blade that is farthest from the sludge pit among the plurality of sludge scraping blades, during the forward movement after the scraping base is moved backward from the normal retreat limit position, It is preferable that the sludge accumulated behind the scraping limit position scraped at the normal retreat limit position is scraped. According to this sludge scraping device, it is possible to efficiently scrape the bottom of the rear side from the scraping limit position where sludge is difficult to collect without adding a new sludge scraping blade at a necessary frequency. .

  According to the sludge scraping apparatus according to the present invention, the swallowing amount can be easily adjusted according to the amount of scum on the water surface.

  Hereinafter, a preferred embodiment of a sludge scraping apparatus according to the present invention will be described with reference to FIGS.

  1 is a diagram showing a sludge scraping device according to an embodiment of the present invention, FIG. 2 is an enlarged view of the vicinity of the flight (sludge scraping blade) and lift bar in FIG. 1, and FIGS. FIG. 8 and FIG. 9 are explanatory diagrams of each state of the lift bar, and FIG. 10 and FIG. 11 are control flowcharts of the sludge scraping device. 3 to 7 show the state of the flight farthest from the sludge pit of the tank, and the configuration of the scum removal unit is omitted for convenience of explanation.

  As shown in FIG. 1, the sludge scraping apparatus 1 of this embodiment is arrange | positioned at the sedimentation basin etc. of a sewage treatment plant, for example, and sews the sludge etc. which accumulate on the bottom part 2b of the tank 2 toward the sludge pit 2a. At the same time, scum and the like floating on the water surface 3 of the tank 2 are removed.

  The sludge scraping device 1 is supported by a scraping base 10 that reciprocates in the longitudinal direction in the tank 2 and swingably supported on the lower side of the scraping base 10, and collects the sludge accumulated on the bottom 2 b of the tank 2. The scum is removed by using the flight (sludge scraping blade) 30 for scraping, the driving device 40 for reciprocating the scraping base 10 substantially parallel to the bottom 2b of the tank 2, and the reciprocating motion of the stirring base 10 And a control unit 60 for controlling the driving device 40.

  As shown in FIG. 1, the tank 2 has a substantially rectangular cross section cut vertically along the longitudinal direction, and sewage is supplied from the left side of FIG. 1 (sewage is supplied toward the longitudinal direction of the tub 2. The sludge pit 2a is provided at the bottom of the sewage supply side of the tank 2, and the sewed sludge is collected in the sludge pit 2a. The downstream bottom 2c of the tank 2 deposits less sludge than the normal bottom 2b.

  As shown in FIGS. 1 and 2, the structure and operation of the scraper 10 that reciprocates in the longitudinal direction of the tank 2, the guide unit 20 that supports the scraper 10 and guides the reciprocation, and the flight 30 are as follows: This is almost the same as that described in Japanese Patent Laid-Open No. 2003-181209. Specifically, the stroking table 10 includes a plurality of main roller support shafts 12 having main rollers 11 at both ends constituting the wheels of the stroking table 10, and two parallel driving direction members 13 extending in the longitudinal direction. As shown in FIG. 2, these main roller support shaft 12 and drive direction member 13 are configured in a ladder shape by intersecting at right angles via coupling plates 12a and 13a. As shown in FIG. 1 and FIG. 2, the main roller 11 is a guide unit 20 having two upper and lower rails each having a substantially U-shaped cross section installed on a pair of side walls 2 d parallel to the longitudinal direction of the tank 2. It is accommodated and supported in the upper main guide rail 21 and its travel is guided. As shown in FIG. 1, the motor 41 constituting the driving device 40 rotates, so that the driving force is transmitted via the chain 42. It is transmitted to the cradle 10 and the cradle 10 reciprocates.

  When this scraping base 10 moves forward, as shown in FIGS. 3 to 7, it is connected to the main roller support shaft 12 of the scraping base 10 via a flight arm 31 that can swing around this axis. The flight 30 thus squeezed the sludge accumulated on the bottom 2b of the tank 2 toward the sludge pit 2a at the first swinging position where the flight 30 hangs down. At this time, the auxiliary roller 32 protruding from the flight arm 31 toward the side wall 2d is swingably provided on the lower surface of the auxiliary guide rail 22 installed at the lower stage of the guide unit 20, as shown in FIG. As shown in FIG. 4, the lower guide flap 33 protruding so as to form an inclined surface of approximately 30 degrees below the auxiliary guide rail 22 pushes away against the spring force and moves forward.

  When the sub-roller 32 passes under the opening 34 formed on the lower surface of the sub-guide rail 22 and adjacent in the forward movement direction (the position of the scraping base 10 at this time is set as the forward limit position), the motor 41 rotates in the reverse direction. (Counterclockwise in the figure), the scraping base 10 starts to move backward, and the sub roller 32 rises along the inclined surface of the lower guide flap 33 and enters the sub guide rail 22 through the opening 34. At this time, the flight arm 31 is rotated in the clockwise direction in the drawing to be inclined, and as shown in FIG. 5, the flight 30 is separated from the bottom portion 2b to remove the sludge that has been scraped in the reverse direction (recovery). The scraping base 10 moves backward without scraping back in the movement direction). When the sub roller 32 approaches the opening 34 adjacent in the backward movement direction, the upper guide flap 35 is swingably installed on the lower surface of the sub guide rail 22 and extends upward against the spring force to open the opening. Pass over 34. When the sub roller 32 passes over the opening 34 (the position of the cradle 10 at this time is set as the retreat limit position), the motor 41 further rotates in the reverse direction and rotates clockwise in the figure, so that the cradle 10 is As shown in FIG. 6, the secondary roller 32 descends along the inclined surface of the lower guide flap 33 and is guided out of the secondary guide rail 22. Such a series of operations is repeated, and the sludge accumulated on the bottom 2b is carried to the sludge pit 2a. Here, in FIGS. 3 to 7, a limit position at which the flight 30 can normally scrape at the bottom 2 b of the tank 2 is a scratch limit position L.

  The main guide rail 21 may be omitted, and the upper surface of the sub guide rail 22 may be used as the main guide rail.

  Further, the spring of the lower guide flap 33 may be omitted, and the lower guide flap 33 may be automatically operated.

  Further, instead of the spring of the upper guide flap 35, a counterweight may be installed at the end of the upper guide flap 35 to operate.

  Here, the characteristic operation of the present invention will be described. The downstream bottom 2c with less sludge accumulation does not need to be scraped at the same frequency as other regions, and is therefore scraped only once in a predetermined number of scraping operations. That is, when the above-described reciprocation is repeated a predetermined number of times, the returning carriage 10 continues to move backward as shown in FIG. 7 even if it passes through the backward limit position. When the upper guide flap 35a disposed farthest from the sludge pit 2a is pushed down and passes through the opening 34a, and the sub roller 32 passes over the opening 34a, the motor 41 further rotates in the reverse direction and rotates clockwise in the figure. And the scraper 10 starts to move forward again, and the sub roller 27 descends along the inclined surface of the lower guide flap 33a and is guided to the outside of the sub guide rail 22, and the sludge accumulated on the downstream bottom 2c. Is raked toward the sludge pit 2a.

  By performing the above-described operation (hereinafter referred to as “scum suction operation”) every predetermined number of reciprocations, the downstream bottom 2c is less likely to collect sludge behind the scraping limit position. Without adding a new flight 30, it is possible to scrape efficiently at a necessary frequency.

  As shown in FIGS. 2 and 3 to 7, the fixing plate 12 a fixed to the main roller support shaft 12 has an arm that prevents further turning counterclockwise from the suspended state of the flight arm 31. The stopper 36 is fixed, and the lower guide flap 33 is provided with a stopper 36 for preventing further rotation in the counterclockwise direction shown in the figure from the inclined state. As shown in FIGS. The flaps 33 and 35 are respectively provided with springs 37 and 38 for smoothly returning from the position rotated by the sub roller 32 to the original position (position shown in FIGS. 3 to 7). A weight may be provided in place of the springs 37 and 38.

  The flight 30 is swung by such a series of operations of the scraper 10 and the sub roller 32, and the sludge scraped to the sludge pit 2a side by a predetermined section (distance between the openings 34, 34) At the position on the sludge pit 2a side from the guide flap 33, it is in a state where it has been temporarily accumulated, and after that, by the flight 30 next to the sludge pit 2a which has returned and returned, it is further moved to the sludge pit 2a side. The section is scraped and the sludge is fed forward by one flight 30 every predetermined section, and is scraped and discharged to the sludge pit 2a.

  As shown in FIGS. 2, 8, and 9, the scum removing unit 50 can rotate the lift pin 51 that moves in accordance with the reciprocating motion of the scraping base 10, the lift bar 52 that is lifted by the lift pin 51, and the lift bar 52. A support member 53 that supports the shaft, a scum pipe 54 that sucks the scum, a scum bar 55 that rotates together with the scum pipe 54, and a lift shaft 56 that connects the scum bar 55 and the lift bar 52 are provided.

  As shown in FIG. 2, the lift pin 51 is formed by a cylindrical pin extending from the lift pin fixing member 51a fixed by sandwiching the driving direction member 13 of the scraping base 10 toward the side wall 2d. Has been. The lift pin 51 does not reverse and come into contact with the lift bar 52 even when the scraping base 10 moves to the normal retreat limit position, but is disposed at a position to be locked to the lower surface 52a of the lift bar 52 when the scum is sucked. Has been.

  The lift bar 52 is pivotally supported by a support member 53 fixed to the guide unit 20 so as to be rotatable about the end 52b, and toward the sludge pit 2a side while being inclined so that the lift pin 51 enters the lower surface 52a. It extends. The support member 53 is provided with a stopper 53 a for preventing the lift bar 52 from rotating downward on the lower surface 52 a side of the end 52 b of the lift bar 52.

  The scum pipe 54 is placed horizontally across the entire width in the short direction of the tank 2 on the water surface 3 on the downstream side of the tank. The scum pipe 54 is supported so as to be rotatable about an axis, and includes an opening 54a extending in the longitudinal direction on a circumferential surface. The scum pipe 54 has a C-shaped cross section, and is normally disposed so that the opening 54a faces upward from the water surface so as not to swallow the scum. Then, the scum on the water surface is swallowed by rotating and immersing the opening 54a in the water.

  The scum bar 55 is formed by extending obliquely downward from the longitudinal end portion of the scum pipe 54, is fixed integrally with the scum pipe 54, and is rotated upward to rotate the scum pipe 54. It is something to be made.

  The lift shaft 56 extends in the vertical direction and has one end pivotally supported by the end portion 52 c of the lift bar 52 and the other end pivotally supported by the end portion 55 a of the scum bar 55, thereby connecting the lift bar 52 and the scum bar 55. To do.

  In the scum removing unit 50 configured as described above, when the cradle 10 is retracted from the normal retreat limit position, the lift pins 51 that move along with the movement of the cradle 10 are the end portions of the lift bar 52. By engaging with the lower surface 52a on the 52c side and moving as it is, as shown in FIG. 9, the lift bar 52 is pushed up from the lower surface side and rotated around the end 52b.

  At this time, as the lift bar 52 rotates, the lift shaft 56 connected to the end 52c is simultaneously pushed upward, and the scum bar 55 is also pushed up, thereby rotating the scum pipe 54. By such an operation, the opening 54a that normally faces upward and exits from the water surface 3 is submerged in water, and the scum on the water surface is swallowed and removed.

  Then, after a certain time has passed, the scraping base 10 starts to move, and the lift pin 51 moves accordingly, and the lift bar 52 lifted by the lift pin 51 returns to its original position by its own weight, and in conjunction therewith. The opening 54a of the scum pipe 54 also comes out of the water again, and the scum suction is interrupted.

  As described above, in the present embodiment, the scum pipe 54 can be driven efficiently by using the reciprocating motion of the scraper 10 for moving the flight 30. Moreover, the swallowing amount of the scum pipe 54 can be changed by adjusting the stop time of the scraping base 10 and the stroke of the reciprocating operation of the lift pin 51 to change the lifting height of the lift bar 52. This makes it possible to easily adjust the swallowing amount in accordance with the amount of scum on the water surface.

  When the lift bar 52 is pushed up, the scum pipe 54 rotates through the lift shaft 56 and the scum bar 55 to swallow the scum, so that the scum can be reliably removed with a simple structure.

  Further, since the lift pin 51 is provided at a position where it is not locked to the lift bar 52 at the normal retreat limit position of the scraping platform 10, normally, the sludge is squeezed without sucking the scum, and only when necessary. Since the scum can be sucked by rotating the scum pipe 54 with the gantry 10 retracted from the normal retreat limit position, the amount of swallowing of the scum can be adjusted more easily.

  The lift pin 51, the lift bar 52, the scum bar 55, and the lift shaft 56 constitute a power conversion mechanism in the present invention.

  Next, a processing procedure executed by the control unit 60 will be described with reference to FIGS. First, as shown in FIG. 10, the state of the automatic operation switch of the sludge scraping device 1 is detected (procedure 101), and when it is confirmed that the switch is turned on, the drive device 40 is rotated clockwise to scrape. The gantry 10 is moved forward (procedure 102). Along with this movement, the flight 30 moves forward while scraping the sludge accumulated on the bottom 2b of the tank forward.

  While the scraper 10 is moving forward, the position information is detected as a numerical value, and it is monitored whether or not the preset advance limit position has been reached (procedure 103). If the set value has not been reached, the driving device 40 is continuously rotated to move the scraping base 10 forward. When the scraping base 10 moves to the forward limit position and reaches the set value, the driving device 40 is stopped (procedure 104).

  Thereafter, the forward flag is turned off and the reverse flag is turned on (procedure 106). The operation is stopped until a predetermined time elapses, and the process waits until the forward position delay timer is entered (procedure 107).

  When a predetermined time elapses and the forward position delay timer is entered, the driving device 40 is rotated counterclockwise, and the scraper 10 is moved backward. Along with this movement, the sub roller 32 is housed in the sub guide rail 22 by the lower guide flap 33 and is separated from the bottom 2b, and moves without scraping back the sludge that has been squeezed in the backward direction ( Procedure 108).

  The position information of the scraping platform 10 is detected as a numerical value, and it is monitored whether or not the preset value of the retreat limit position has been reached (procedure 109). If the set value has not been reached, the drive device 40 is continuously rotated to move the scraping base 10 backward. When the scraping base 10 moves to the retreat limit position and reaches the set value, the counter is incremented by one on the assumption that one round-trip operation has been completed (procedure 111). Note that the lift pin 51 does not come into contact with the lift bar 52 even when the scraper base 10 comes to the retreat limit position.

  Here, referring to the counter (procedure 112), if the reciprocating operation has not been performed up to the predetermined number N, the driving device 40 is stopped (procedure 113). The scraping base 10 is continuously moved back to a scum suction operation (described later).

  After stopping the driving device 40, the reverse flag is turned off and the forward flag is turned on (procedure 114), the operation is stopped until a predetermined time elapses, and the operation waits until the reverse position delay timer is entered (step 114). Procedure 116). Up to here is the normal reciprocating motion of the scraper 10.

  On the other hand, if it is determined in step 112 that the reciprocating operation has been performed a predetermined number of times N, the procedure shifts to the scum suction operation, and the scraper 10 is continuously moved backward. The position information of the scraper 10 is detected as a numerical value, and it is monitored whether or not the preset value of the scum operation limit position has been reached (procedure 117). If the set value has not been reached, the drive device 40 is continuously rotated to move the scraping base 10 backward.

  Here, when the scraping base 10 moves rearward from the retreat limit position, the lift pin 51 is locked and pushed up to the lower surface 52a of the lift bar 52, whereby the scum pipe 54 is rotated and the scum is opened from the opening 54a. Swallow. At this time, the last flight 30 retreats while maintaining an inclined state.

  When the scraping base 10 moves to the scum operation limit position and reaches the set value, the drive device 40 is stopped (procedure 118). Thereafter, the reverse flag is turned off, the forward flag is turned on (procedure 119), the operation is stopped until a predetermined time elapses, and the process waits until the scum operation delay timer is entered (procedure 121). When the predetermined time has elapsed and the scum operation delay timer is entered, the counter is reset (procedure 122). Up to here is the scum suction operation of the scraper 10.

  When the normal reciprocating operation or scum operation is completed, it is detected whether or not the automatic stop switch is turned on (procedure 123). If the automatic stop switch is turned on, the drive unit is stopped (procedure 124) and waits until the automatic operation switch is turned on again. If the automatic stop switch is not turned on, the process returns to step 102 in FIG. 10 to start forward operation. At this time, the last flight 30 descends from the last lower guide flap 33a and moves forward while scraping the sludge accumulated on the downstream bottom 2c, so that it is behind the scraping limit position L. It can scrape the accumulated sludge.

  As described above, according to the present embodiment, the amount of scum swallowed can be easily adjusted only by adjusting the stop time, the scum operation limit position, and the number of scum operations of the scraper 10.

  Although the present invention has been specifically described above based on the embodiment, the present invention is not limited to the above embodiment. For example, in the above embodiment, nothing is provided near the water surface 3 of the tank 2. However, the scum pipe may easily enter the scum by arranging a blade member that moves in conjunction with the reciprocating motion of the scraper 10.

It is a figure which shows the sludge scraping apparatus which concerns on embodiment of this invention. FIG. 2 is an enlarged view of the vicinity of a flight and lift bar attachment portion in FIG. 1. It is a schematic diagram which shows the state of the flight at the time of a forward motion. It is a schematic diagram which shows the state in which a sub roller pushes down a lower side guide flap at the time of a forward motion. It is a schematic diagram which shows the state of the flight at the time of backward movement. It is a schematic diagram which shows the state in which a sub-roller descends along the inclined surface of a lower side guide flap at the time of a forward motion. It is a schematic diagram which shows the state of the flight at the time of scum suction | inhalation. It is a schematic diagram which shows the state before a lift bar is pushed up. It is a schematic diagram which shows the state by which the lift bar was pushed up. It is a control flowchart of a sludge scraping apparatus. It is a control flowchart of a sludge scraping apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Sludge scraping apparatus, 2 ... Tank, 2a ... Sludge pit, 2b ... Bottom (bottom part of tank), 3 ... Water surface, 10 ... Scratch rack, 30 ... Flight (sludge scraping blade), 51 ... Lift pin, 52 ... lift bar, 52b, 52c ... end, 52 ... lower surface, 54 ... scum pipe, 54a ... opening, 55 ... scum bar, 56 ... lift shaft.

Claims (4)

A scraper that reciprocates in the longitudinal direction of the tank in the tank;
A plurality of sludge scraping blades that are supported by the scraping stand and scrape the sludge accumulated on the bottom of the tank;
An opening for sucking up the scum that floats on the surface of the treated water contained in the tank, and is laid horizontally in the short direction of the tank at the height of the water surface, the opening being located with respect to the treated water A scum pipe that is pivotally supported so as to appear and appear,
E Bei and a power conversion mechanism for converting reciprocating motion to the rotation of the Sukamupaipu of the raking frame,
The power conversion mechanism is
A lift bar pivotally supported at one end;
A lift pin that reciprocates integrally with the scraping base, engages with the lower surface of the lift bar, and rotates the lift bar;
A link mechanism that has one end connected to the other end of the lift bar, the other end connected to the scum pipe, and links the two to rotate the scum pipe in response to the rotation of the lift bar;
The lift pin is provided at a position where the lift bar is not locked to the lift bar at a normal retreat limit position of the scraping base,
The sludge scraping device , wherein the lift pin is engaged with the lift bar when the scraping base is retracted from the normal retreat limit position . The link mechanism is
A scum bar that rotates integrally with the scum pipe;
The sludge scraping device according to claim 1 , further comprising: a lift shaft having one end pivotally supported by the other end of the lift bar and the other end pivotally supported by the scum bar and extending in a vertical direction. . The sludge scraping device according to claim 1 or 2 , wherein the scraper is moved backward from the normal retreat limit position every predetermined number of reciprocations of the scraper. The sludge scraping blade that is farthest from the sludge pit among the plurality of sludge scraping blades is in the normal retreat limit position at the time of forward movement after the scraping base is retreated from the normal retreat limit position. The sludge scraping device according to any one of claims 1 to 3, wherein the sludge accumulated behind the scraping limit position to be scraped is scraped.

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