JP2016016371A - Sludge scraper and sludge scraping method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sludge scraper in which the breaking of a notch chain can be effectively prevented.SOLUTION: The sludge scraper of the present invention is installed under an environment where an aqueous solution containing a strong acid or a strong alkali may adhere to the sludge scraper. This sludge scraper comprises: an endless notch chain 7 comprised of ring plates 41 each having notches 41b; a drive wheel 3, having a plurality of pins 3a, engaged with notches 41b of the notch chain 7 and rotated by a driving source; driven wheels 4,5,6 rotating with the notch chain 7; and a flight movable body 8 having a flight plate 20 for raking sludge and fixed to the notch chain 7. The notch chain 7 is trained around the drive wheel 3 and the driven wheels 4,5,6 and is configured so as to circulate under the rotation of the drive wheel 3 and is composed of a metal having corrosion resistance and acid resistance.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a sludge scraper that is installed in a sedimentation basin and scrapes sludge accumulated on the bottom of the sedimentation basin and scrapes scum floating on the water surface of the sedimentation basin. The present invention also relates to a sludge scraping method using the sludge scraper.

  As the chain travels, a long flight board circulates inside the sedimentation basin, and when the flight board travels along the bottom of the sedimentation basin, the sludge that accumulates on the bottom of the pond is scraped and the flight board stays in the sedimentation tank. There is known a sludge scraping machine that scrapes scum floating on the water surface when traveling on the water surface. In this sludge scraper, as described above, the sludge and scum are traveled along the guide rail while the flight plate runs along the guide rail in the settling basin as the chain runs between the drive wheel and the driven wheel. Scraping is performed.

  As a chain used in this sludge scraping machine, a notch chain constituted by a link plate having a notch (notch) is known. The drive wheel for driving the notch chain is provided with a plurality of pins, and the notch chain is driven by rotating the drive wheel with these pins engaged with the notches of the notch chain.

  This notch chain is formed from a synthetic resin such as polyacetal. Polyacetal has been widely used as a material constituting the notch chain of a sludge scraper because it has a large advantage that it is lighter than metal and has excellent formability.

  In the first sedimentation basin where the sludge scraper is installed, hydrogen sulfide is generated by bacteria and bacteria. Hydrogen sulfide has a strong irritating odor, and the upper part of the first sedimentation basin is often covered with a lid member as a countermeasure against odors in the vicinity.

  Condensed water adheres to the wall surface above the water surface in the first sedimentation tank sealed by the lid member, the back surface of the lid member, etc., and hydrogen sulfide is dissolved in this condensed water. The water in which hydrogen sulfide is dissolved is weakly acidic, but the water in which this hydrogen sulfide is dissolved is first converted into strongly acidic sulfuric acid by bacteria and bacteria present in the sedimentation basin. The sulfuric acid changed from the hydrogen sulfide is concentrated as the water evaporates. This concentrated sulfuric acid may come into contact with the notch chain. Furthermore, dew condensation water may be generated on the surface of the notch chain exposed from the water surface, and hydrogen sulfide may dissolve in the dew condensation water to generate sulfuric acid. Polyacetal, which is the material of the notch chain, is weak against strong acids and may be broken due to deterioration when sulfuric acid adheres. Moreover, sodium hypochlorite may be added to water to be treated as a water treatment chemical. In this case, since high concentration sodium hypochlorite is dripped at a sedimentation basin, high concentration sodium hypochlorite may adhere to a notch chain. Polyacetal is weak against strong alkali, and when sodium hypochlorite adheres to the notch chain, the notch chain may deteriorate and break. If the operation of the sludge scraper is continued while the notch chain is broken, the notch chain and the flight plate may be damaged due to dropping off of the flight plate.

  If the notch chain is always submerged in the water in the initial sedimentation basin, the sulfuric acid or dripped sodium hypochlorite is diluted with water and does not directly contact the notch chain, so sulfuric acid or hypochlorous acid The possibility of chain breakage due to sodium is reduced. However, in recent sewage treatment, operations such as stopping the sludge scraper in the first sedimentation basin and increasing the load on the aeration tank (aeration tank) or the final sedimentation basin located after the first sedimentation basin are performed. Sometimes done. In this case, in order to prevent chain breakage, the amount of sewage flowing into the first settling basin and the amount of sewage discharged from the first settling basin should be adjusted so that the water level in the first settling basin is always above the notch chain. Need to control. This control is very cumbersome and difficult. In addition, it was necessary to operate the sludge scraper even if the inflow of sewage to the settling basin was stopped first so that the notch chain was submerged.

JP 2013-52347 A

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a sludge scraper that can effectively prevent the notch chain from being broken. Moreover, an object of this invention is to provide the sludge scraping method using this sludge scraping machine.

  In order to achieve the above-described object, one aspect of the present invention is an endless notch that is a sludge scraper to which an aqueous solution containing a strong acid or a strong alkali may adhere, and includes a link plate having a notch. A chain, a plurality of pins that engage with the notches of the notch chain, a drive wheel that is rotated by a driving device, a driven wheel that rotates with the notch chain, and a flight plate that scrapes sludge. A flight movable body fixed to the notch chain, and the notch chain is stretched over the drive wheel and the driven wheel, and is configured to circulate by rotation of the drive wheel, The notch chain is made of a metal that has corrosion resistance and acid resistance. It is a machine.

  In a preferred aspect of the present invention, the metal having corrosion resistance and acid resistance is selected from austenitic stainless steel, duplex stainless steel, titanium, and precipitation hardening stainless steel.

In a preferred aspect of the present invention, attachment pieces are attached to both ends of the flight plate, the notch chain is fixed to a base fixed to the attachment piece, and a portion of the attachment piece where the notch chain is fixed A notch is provided on the opposite side.
In a preferred aspect of the present invention, the attachment piece and the base are made of a metal having the corrosion resistance and acid resistance, and the attachment piece and the base fold the metal having the corrosion resistance and acid resistance. Or by pressing or casting with a mold.

  In a preferred aspect of the present invention, a tooth skip prevention member that prevents tooth skipping of the notch chain is provided on the outer side in the radial direction of the drive wheel, and the tooth skip prevention member follows the movement locus of the notch chain. It has an arcuate outer shape.

In a preferred aspect of the present invention, the apparatus further comprises a tension adjusting device for adjusting the tension of the notch chain.
In a preferred aspect of the present invention, the notch chain is fixed to the flight movable body at substantially the same height as an intermediate position in the height direction of the flight plate.

  Another aspect of the present invention is a flight movable body fixed to the notch chain by circulating a notch chain made of a metal having corrosion resistance and acid resistance, spanned between a drive wheel and a driven wheel. The sludge scraping method is characterized by scraping sludge accumulated at the bottom of the first sedimentation basin and scum floating on the water surface of the first sedimentation basin.

  According to the sludge scraper of the present invention, the notch chain is made of a corrosion-resistant and acid-resistant metal. Therefore, even if a small amount of aqueous solution containing strong acid or strong alkali such as sulfuric acid generated by the action of bacteria or bacteria adheres to the notch chain, the surface of the notch chain corrodes or the pores are locally opened, Since the strength of the notch chain can be maintained with the remaining healthy part, the notch chain does not break. Further, since the notch chain is made of metal, the chain strength can be increased as compared with a synthetic resin such as polyacetal. In this way, a notch chain composed of corrosion-resistant and acid-resistant metals does not cause a significant decrease in strength due to corrosion even when a small amount of an aqueous solution containing a strong acid or strong alkali adheres, and the mechanical strength also increases. Can be effectively prevented.

It is a figure which shows the outline | summary of the sludge scraping machine which concerns on one Embodiment of this invention. FIG. 2A is a top view of a part of the notch chain, and FIG. 2B is a side view of a part of the notch chain. FIG. 3A is a front view of the drive wheel, and FIG. 3B is a top view of the drive wheel. It is a figure which shows a flight movable body. It is a figure which shows a flight movable body and a water surface guide rail. It is the figure which looked at the flight movable body and water surface guide rail which were shown in FIG. 5 from the top. It is a figure which shows a tooth skip prevention member and a notch chain. It is a side view of a tension adjusting device. It is the enlarged view which showed the state in which the flight movable body has passed the underwater wheel. It is an example of the schematic flow of the standard activated sludge method which processes sewage.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram showing an outline of a sludge scraping machine. The sludge scraper in the illustrated example is disposed in the first sedimentation basin of the sewage treatment plant. In addition, a sludge scraper may be arrange | positioned in the first settling basin of a factory wastewater treatment facility. Further, the sludge scraper may be disposed in the final sedimentation basin of these sewage treatment plants and factory wastewater treatment facilities. Or you may arrange | position to the sedimentation basin of a water purification plant. Under these exemplified sedimentation basin environments, the sludge scraper may come into contact with an aqueous solution containing a strong acid or strong alkali. In particular, since the sulfuric acid, which is a strong acid, is likely to be produced in the first sedimentation basin of the sewage treatment plant and the sedimentation basin of the factory wastewater treatment facility, It is preferable to arrange in a sedimentation basin of a wastewater treatment facility. This sludge scraper includes a drive device 2, a drive wheel 3, a water surface wheel 4, submersible wheels 5 and 6, and a pair of endless belts spanned between these wheels. And a plurality of flight movable bodies 8 fixed to the notch chain 7 at a predetermined interval.

  The pair of notch chains 7 is initially arranged in parallel in the settling basin 1, and these notch chains 7 are circulated by the drive wheel 3 connected to the drive device 2. As the notch chain 7 circulates, the flight movable body 8 initially travels inside the settling basin 1.

  When the flight movable body 8 first travels on the pond bottom side of the settling basin 1, as shown in FIG. 1, the flight movable body 8 scrapes the sludge accumulated on the pond bottom to the sludge storage section 1a and travels on the water surface side. When doing so, the scum floating on the water surface is raked up to the scum clearance 9. In order to guide the traveling of the flight movable body 8, for example, a water surface guide rail 27 and an underwater guide rail 11 that are light and have excellent corrosion resistance are disposed along the side wall of the settling basin 1. Further, a pond bottom guide rail 12 for guiding the travel of the flight movable body 8 is laid on the pond bottom.

  The drive wheel 3 is connected to a sprocket wheel (not shown) that receives power from the drive device 2 via a drive chain 2a. The water surface wheel 4, the underwater wheel 5, and the underwater wheel 6 are all driven wheels. Therefore, the water surface wheel 4, the underwater wheel 5, and the underwater wheel 6 are rotated according to the circulating notch chain 7. The underwater wheel 5 is configured to be able to adjust the tension of the notch chain 7 by moving back and forth in the horizontal direction.

  An overflow dam is attached to the scum skimmer 9 so that it can be opened and closed. The scum that is initially floating on the liquid surface of the settling basin 1 is caused to flow into the trough 9 a together with water by the flight movable body 8. Yes. The scum clearance 9 may be a pipe clearance that rotates a pipe having a notch. An overflow dam 14 is provided in the first sedimentation basin 1. Initially, the water in the settling basin 1 is discharged beyond the overflow weir 14.

  FIG. 2 is a drawing in which a part of the notch chain 7 is extracted and drawn. More specifically, FIG. 2A is a top view of a part of the notch chain 7, and FIG. 2B is a side view of a part of the notch chain 7. 2A and 2B, the notch chain 7 is configured to be endless by connecting a plurality of link units 40 including a pair of link plates 41 and 41 with connecting pins 43. As shown in FIG. The A bent portion 41 a formed by bending a part of the link plate 41 is formed on one end side of the link plate 41. A first pin hole 41c into which the connection pin 43 is inserted is formed on the distal end side of the link plate 41 with respect to the bent portion 41a. A second pin hole 41 d into which the connecting pin 43 is inserted is also formed on the other end side of the link plate 41. A fixing pin 44 for fixing the notch chain 7 to the base 10 fixed to the attachment piece 21 of the flight movable body 8 described later is inserted between the bent portion 41a and the second pin hole 41d. A pin hole 41e is formed. In the illustrated example, one third link plate 41 is provided with two third pin holes 41e.

  As shown in FIG. 2A, the pair of link plates 41, 41 are such that the bent portions 41 a, 41 a of the link plates 41, 41 are based on the center line CL between the link plates 41, 41. It arrange | positions facing so that it may become symmetrical. Therefore, the distance between the pair of first pin holes 41c and 41c in the pair of link plates 41 and 41 of the link unit 40 is the distance between the pair of second pin holes 41d and 41d in the pair of link plates 41 and 41. Shorter than.

  When connecting the two link units 40, 40 having such a configuration, the second pin hole 41d of the other link unit 40 is positioned outside the first pin hole 41c of the one link unit 40. Two link units 40, 40 are arranged in Then, the connecting pin 43 is inserted into the first pin holes 41 c and 41 c in one link unit 40 and the second pin holes 41 d and 41 d in the other link unit 40. By fixing a stopper (not shown) or the like to the connecting pin 43, the connecting pin 43 is prevented from falling off the first pin holes 41c and 41c and the second pin holes 41d and 41d. In this way, by connecting the plurality of link units 40, 40,... Using the connecting pin 43, and finally connecting the link unit at the front end to the link unit at the rear end, an endless notch A chain 7 is constructed.

  As shown in FIG. 2B, notches (notches) 41b are formed on the outer periphery of the link plate 41. The notches 41b engage with a plurality of pins 3a arranged on the peripheral edge of the drive wheel 3 described later. The notch 41b is disposed close to the second pin hole 41d. With the notch 41b engaged with the pin 3a of the drive wheel 3, the drive wheel 3 rotates, whereby the notch chain 7 is circulated.

  FIG. 3A is a front view of the drive wheel 3, and FIG. 3B is a top view of the drive wheel 3. The drive wheel 3 has a plurality of pins 3 a that engage with notches (notches) formed in the notch chain 7. These pins 3 a are arranged at the peripheral edge of the drive wheel 3 and are arranged at equal intervals in the circumferential direction of the drive wheel 3.

  FIG. 4 is a diagram showing the flight movable body 8. As shown in FIG. 4, the flight movable body 8 includes a flight plate (scraping plate) 20 that scrapes sludge and scum, attachment pieces 21 attached to both ends of the flight plate 20, and each attachment piece 21. A first guide shoe 23 fixed to the upper part, a base 10 fixed to the lower part of each attachment piece 21, and a second guide shoe 24 fixed to the lower part of each attachment piece 21 are provided. The notch chain 7 is coupled to the base 10 so that the flight movable body 8 is pulled by the notch chain 7 and travels. A notch 25 is formed on the opposite side of the attachment piece 21 where the notch chain 7 is fixed.

  As shown in FIG. 4, the notch chain 7 is connected to the flight movable body 8 at substantially the same height as the intermediate position in the height direction of the flight plate 20. When the notch chain 7 is attached at such a position, the driving force transmitted from the notch chain 7 to the flight movable body 8 is added to the substantially intermediate position in the height direction of the flight plate 20 in order to circulate the flight movable body 8. It is done. In other words, the flight board 20 travels in the first settling basin 1 by being pulled by the notch chain 7 at a substantially intermediate position in the height direction of the flight board 20. By configuring the flight plate 20 so as to be pulled at a substantially intermediate position in this way, it is possible to reduce the fact that the flight plate 20 is inclined obliquely due to the action of the driving force transmitted from the notch chain 7.

  The attachment piece 21, the base 10, the first guide shoe 23, and the second guide shoe 24 constitute an attachment unit. This attachment unit is detachably attached to the flight board 20. Therefore, the sludge scraper can be installed in the first sedimentation basin 1 having various pond widths simply by attaching the attachment unit to the prepared flight boards 20 having different lengths.

  FIG. 5 is a diagram showing the flight movable body 8 and the water surface guide rail 27, and FIG. 6 is a view (plan view) of the flight movable body 8 and the water surface guide rail 27 as seen from above. As shown in FIGS. 5 and 6, the water surface guide rail 27 is supported by a water surface guide rail support member 30 that is first fixed to the side wall 1 b of the settling basin 1. The water surface guide rail support members 30 are arranged at equal intervals along the water surface guide rail 27. The second guide shoe 24 is fixed to the lower part of the attachment piece 21 and is located on the water surface guide rail 27.

  The base 10 fixed to the lower part of the attachment piece 21 has a U-shaped cross section, and the bottom surface of the base 10 is fixed to the attachment piece 21. On both side surfaces of the base 10, through holes (not shown) into which the fixing pins 44 are inserted are provided. When connecting the base 10 and the notch chain 7, the base 10 is positioned so that the through hole of the base 10 is located outside the third pin hole 41 e (see FIG. 2B) of the notch chain 7. 10 and the notch chain 7 are arranged. Then, the fixing pin 44 is inserted into the through hole of the base 10 and the third pin hole 41e. The notch chain 7 is fixed to the base 10 by attaching a stopper (not shown) or the like to the fixing pin 44.

  When the notch chain 7 is driven by the drive wheel 3 and the flight movable body 8 travels on the water surface, the second guide shoe 24 slides on the water surface guide rail 27 and the second guide shoe 24 is guided by the water surface guide rail 27 to travel. To do. When the flight movable body 8 travels on the underwater guide rail 11, the second guide shoe 24 slides on the underwater guide rail 11, and the second guide shoe 24 travels while being guided by the underwater guide rail 11. The first guide shoe 23 is for traveling by being guided by the pond bottom guide rail 12 when the flight movable body 8 travels on the pond bottom.

  As described above, the flight movable body 8 has two types of guide shoes 23 and 24 for the pond bottom, the water surface, and the underwater, and the flight movable body 8 includes the pond bottom guide rail 12, the underwater guide rail 11, The vehicle travels while sliding on the water surface guide rail 27. The water surface guide rail 27 and the second guide shoe 24 for the underwater guide rail 11 are attached to the end of the flight movable body 8 so that the water surface guide rail support member 30 extending from the side wall 1b of the first settling basin 1 can be formed. Only to make it smaller.

  Since the first guide shoe 23 for the pond bottom guide rail 12 is installed inward from the end of the flight movable body 8, the flight movable body 8 remains on the pond bottom guide rail 12 even if derailed once. It is in. For this reason, as long as the notch chain 7 does not come off the wheel, the flight movable body 8 travels while being pulled by the notch chain 7, and therefore, when the first guide shoe 23 of the derailed flight movable body 8 travels close to the wheel. The first guide shoe 23 automatically returns onto the pond bottom guide rail 12.

  As described above, the water level of the initial sedimentation basin 1 is determined by the overflow weir 14 and the like, and the water level is usually slightly below the upper end of the flight movable body 8 as shown in FIG. The water surface guide rail 27 is located below the water surface. Furthermore, the water surface guide rail support member 30 is also located below the water surface.

  FIG. 7 is a view showing a tooth skip prevention member and a notch chain. The tooth skip prevention member 16 is disposed radially outward of the drive wheel 3 so as to surround a part of the drive wheel 3. The tooth skipping prevention member 16 is first fixed to the wall surface of the settling basin 1 through the bracket 18. The portion of the tooth skipping prevention member 16 that faces the notch chain 7 has an arc shape along the movement locus of the notch chain 7 that travels on the drive wheel 3. Further, the tooth skipping prevention member 16 is disposed in the vicinity of the notch chain 7 or between the link plates 41, and is disposed at a position where it is not in contact with the notch chain 7 in a normal state.

  If the notch chain 7 extends with time, the notch chain 7 may be lifted from the drive wheel 3 and the notch 41 b of the notch chain 7 may be disengaged from the pin 3 a of the drive wheel 3. When the notch chain 7 is detached from the pin 3a, the notch chain 7 jumps so-called. If the tooth skipping prevention member 16 is provided, the top surface of the notch chain 7 and the tooth skipping prevention member 16 come into contact with each other even if the notch chain 7 is about to come off the drive wheel 3. As a result, the notch chain 7 cannot move further away from the drive wheel 3, and the tooth skipping of the notch chain 7 can be effectively prevented. In addition, by arranging the tooth skipping prevention member 16 at a position where the tooth skipping prevention member 16 enters between the link plates 41, the trajectory of the notch chain 7 can be controlled.

  When the flight movable body 8 travels around the drive wheel 3, the tooth skip prevention member 16 enters the notch 25 formed in the attachment piece 21 described above. A minute gap is formed between the notch 25 and the tooth skip prevention member 16 so that the flight movable body 8 can travel without contacting the tooth skip prevention member 16.

  In place of the tooth skipping prevention member 16 or in combination with the tooth skipping prevention member 16, a tension adjusting device (tensioner) 50 that applies tension to the notch chain 7 by its own weight may be provided. FIG. 8 is a side view of the tension adjusting device. In FIG. 8, the notch chain 7 is drawn with a dashed-dotted line.

  As shown in FIG. 8, the tension adjusting device 50 includes an idle roller 51 that can rotate as the notch chain 7 travels, a support member 52 that rotatably supports the idle roller 51, and a support member 52. And a weight 54 fixed to the upper end portion. The support member 52 extends in the vertical direction, and a guide member 53 that guides the movement of the support member 52 in the vertical direction is first fixed to the wall surface of the settling basin 1 or the like. The idle roller 51 passes through the notch 25 provided in the attachment piece 21 described above.

  In the tension adjusting device 50 having such a configuration, the idle roller 51 and the support member 52 are urged downward by the weight of the weight 54. As a result, the notch chain 7 is pressed downward by the idle roller 51. Therefore, even if the notch chain 7 extends with time, the tension adjusting device 50 can press the notch chain 7 downward and apply an appropriate tension to the notch chain 7.

  In conventional sludge scraping machines, polyacetal has been widely used because the notch chain has a great advantage that it is lighter than metal and has excellent formability. However, polyacetal has the disadvantage of being weak against strong acids and strong alkalis. In the embodiment described so far, the notch chain 7 is made of a metal having corrosion resistance and acid resistance. In the present specification, the metal having corrosion resistance and acid resistance refers to corrosion resistance and acid resistance such as painting in an environment where an aqueous solution containing a strong acid or strong alkali such as the first settling basin 1 is in contact with a small amount of the notch chain 7. It is a generic term for metals whose materials themselves have corrosion resistance and acid resistance without performing surface treatment for improvement.

  The metal having corrosion resistance and acid resistance constituting the notch chain 7 is selected from, for example, austenitic stainless steel represented by SUS304, duplex stainless steel, titanium, and precipitation hardening stainless steel. If the sludge does not contain seawater, hot spring water, etc., it is preferable from the viewpoint of cost and the like to use SUS304. In a sedimentation basin that requires more corrosion resistance and acid resistance than SUS304, it is preferable to use SUS316. In addition to SUS304 and SUS316, SCS13 or SCS16 can be used as an austenitic stainless steel. For austenitic stainless steels such as SUS304 and SUS316, duplex stainless steels may be used if the corrosion resistance, acid resistance, and strength are insufficient.

  Thus, in this embodiment, the notch chain 7 is comprised from the metal which has corrosion resistance and acid resistance. Therefore, an aqueous solution containing a strong acid such as sulfuric acid or a strong alkali (for example, a drug dripped into a settling basin of a water treatment plant or a factory wastewater treatment facility) generated in the first settling basin 1 by the action of bacteria or bacteria is notch chain 7. Even if a small amount adheres to the surface of the notch chain 7 and the surface of the notch chain 7 is corroded or locally perforated, the strength of the notch chain 7 can be maintained at the remaining healthy portion, so the notch chain 7 will not break. . Further, since the notch chain 7 is made of metal, the chain strength can be increased as compared with a synthetic resin such as polyacetal. In this way, the notch chain 7 made of a metal having corrosion resistance and acid resistance does not cause a significant decrease in strength due to corrosion even when a small amount of an aqueous solution containing a strong acid or strong alkali adheres, and mechanical strength also increases. Breakage of the notch chain 7 can be effectively prevented.

  The attachment piece 21 and the base 10 may be made of a metal having corrosion resistance and acid resistance. In this case, it is preferable that the attachment piece 21 and the base 10 are formed by bending a metal plate. Moreover, the attachment piece 21 and the base 10 may be formed by pressing a metal plate. Alternatively, the attachment piece 21 and the base 10 may be formed by casting with a mold. The metal used for the attachment piece 21 and the base 10 is preferably the same as the metal constituting the notch chain 7.

  FIG. 9 is an enlarged view showing a state in which the flight movable body 8 passes through the underwater wheel 5. The underwater wheel 5 is rotatably supported by the underwater wheel shaft 5a. The underwater wheel 5 is in contact with the notch chain 7 and is rotated with the circulation of the notch chain 7. As shown in FIG. 9, the width W <b> 1 of the region in contact with the notch chain 7 of the underwater wheel 5 is larger than the width W <b> 2 of the notch chain 7. More specifically, the width W1 of the region in contact with the notch chain 7 of the underwater wheel 5 is at least twice the width W2 of the notch chain 7.

  If the notch chain 7 is made of metal, the wear of the driven wheels 4, 5, 6 due to the notch chain 7 coming into contact with the driven wheels 4, 5, 6 increases, and the life of the driven wheels 4, 5, 6 is shortened. There is concern. As shown in FIG. 9, when the underwater wheel 5 is configured to be wide, the life of the underwater wheel 5 can be extended as described below.

  When the underwater wheel 5 is worn due to contact with the notch chain 7, the underwater wheel 5 is once extracted from the underwater wheel shaft 5a. If the underwater wheel 5 is inserted into the underwater wheel shaft 5a in the opposite direction with the insertion direction changed (that is, inserted so that the rotation direction of the underwater wheel 5 is opposite), the underwater wheel 5 is notched chain 7. The part that comes into contact with is a part that is not yet worn. As a result, the underwater wheel 5 once worn can be used again. The configuration in which the driven wheel is configured to be wide is applicable not only to the underwater wheel 5 but also to the water surface wheel 4 and the underwater wheel 6.

  The sludge scraper according to the embodiment described so far is suitably used, for example, for an initial settling basin in sewage treatment. FIG. 10 is an example of a schematic flow of a standard activated sludge method for treating sewage. As shown in FIG. 10, the sewage is first supplied to the sand basin 70, and large foreign matters (large dust, stones, etc.) are removed in the sand basin 70. The sewage discharged from the settling basin 70 is first supplied to the settling basin 1. In the first sedimentation basin 1, small foreign matters that could not be removed by the sand basin 70 are removed by sedimentation due to the foreign weight of the foreign matter. In the first sedimentation basin 1, as described above, the endless notch chain 7 spanned between the drive wheel 3 and the driven wheels 4, 5, 6 is circulated to move the flight connected to the notch chain 7. The body 8 rakes the sludge accumulated on the bottom of the first sedimentation basin 1 and the scum floating on the water surface of the first sedimentation basin 1. The notch chain 7 is made of a metal having corrosion resistance and acid resistance. Sediment sludge scraped to the sludge storage part 1a (see FIG. 1) by the sludge scraper is sent to a sludge treatment apparatus (not shown).

  First, the sewage discharged from the settling basin 1 is supplied to an aeration tank (aeration tank) 71. Air is fed into the sewage supplied into the aeration tank 71, and microorganisms are propagated by this air. The propagated microorganisms decompose soil in the sewage, and flocs are formed during the decomposition process. The sewage discharged from the aeration tank 71 is supplied to the final settling basin 72. In the final sedimentation basin 72, flocs formed in the aeration tank 71 are settled. The supernatant liquid of the final sedimentation basin is supplied to the disinfection facility (sterilization facility) 73 as treated water, and the treated water sterilized using chlorine or the like in the disinfection facility 73 is discharged into public water areas.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea described in the claims and the specification and drawings. Is possible.

1 First sedimentation basin 1a Sludge reservoir 1b Side wall 2 Drive device 3 Drive wheel 3a Pin 4 Water surface wheel (driven wheel)
5,6 Underwater wheel (driven wheel)
7 notch chain 8 flight movable body 9 scum clearance 10 base 11 underwater guide rail 12 pond bottom guide rail 14 overflow dam 16 tooth jump prevention member 18 bracket 20 flight plate 21 attachment piece 23 guide shoe for pond bottom guide rail 24 guard rail and underwater Guide shoe for guide rail 25 Notch 30 Water surface guide rail support member 40 Link unit 41 Link plate 41a Bent part 41b Notch (notch)
41c 1st pin hole 41d 2nd pin hole 41e 3rd pin hole 43 Connection pin 44 Fixing pin 50 Tension adjusting device 51 Free-rolling roller 52 Support member 53 Guide member 54 Weight 70 Sedimentation basin 71 Aeration tank
72 Final sedimentation basin 73 Disinfection equipment (sterilization equipment)

Claims (8)

A sludge scraping machine to which an aqueous solution containing a strong acid or strong alkali may adhere,
An endless notch chain composed of a link plate having a notch;
A drive wheel having a plurality of pins engaged with the notches of the notch chain and rotated by a drive device;
A driven wheel that rotates with the notch chain;
A flight plate for scraping sludge, and a flight movable body fixed to the notch chain,
The notch chain is spanned between the drive wheel and the driven wheel, and is configured to circulate by rotation of the drive wheel,
The said notch chain is comprised from the metal which has corrosion resistance and acid resistance, The sludge scraper characterized by the above-mentioned.   The sludge scraper according to claim 1, wherein the metal having corrosion resistance and acid resistance is selected from austenitic stainless steel, duplex stainless steel, titanium, and precipitation hardening stainless steel. Attachment pieces are attached to both ends of the flight board,
The notch chain is fixed to a base fixed to the attachment piece,
The sludge scraper according to claim 1, wherein a notch is provided on the attachment piece on a side opposite to a portion where the notch chain is fixed.   The attachment piece and the base are made of the corrosion-resistant and acid-resistant metal, and the attachment piece and the base are bent or pressed with the corrosion-resistant and acid-resistant metal, 4. The sludge scraper according to claim 3, wherein the sludge scraper is formed by casting with a mold.   A tooth skip prevention member for preventing tooth skipping of the notch chain is provided on the outer side in the radial direction of the drive wheel, and the tooth skip prevention member has an arcuate outer shape along the movement locus of the notch chain. The sludge scraper according to any one of claims 1 to 4.   The sludge scraping device according to any one of claims 1 to 5, further comprising a tension adjusting device that adjusts a tension of the notch chain.   The sludge scraping according to any one of claims 1 to 6, wherein the notch chain is fixed to the flight movable body at substantially the same height as an intermediate position in the height direction of the flight plate. Machine.   By circulating a notch chain made of corrosion-resistant and acid-resistant metal, which is stretched between a drive wheel and a driven wheel, a flight movable body fixed to the notch chain, at the bottom of the first sedimentation basin A method for scraping sludge, characterized in that the sludge that accumulates and the scum that floats on the surface of the first sedimentation basin are scraped.

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