Contaminant removal screen device

Abstract

To provide an impurity removing screen device capable of efficiently transferring impurities.SOLUTION: An impurity removing screen device 6 for raw sludge includes a plurality of first movable screen members 61 which are arranged with a distance in a thickness direction, have a plurality of first stage parts 611 in a transfer direction of impurities X, and are repeatedly moved to upper and lower sides, a plurality of second movable screen members 62 which are arranged between the first movable screen members 61, have a plurality of second stage parts 621 in the transfer direction of the impurities X and are repeatedly moved to the upper and lower sides, and a driving mechanism 65 having a first frame 651 to which the plurality of first movable screen members 61 are fixed and a second frame 652 to which the plurality of second movable screen members 62 are fixed, wherein the driving mechanism 65 moves a first frame 651 and a second frame 652, and thereby moves the first movable screen members 61 and the second movable screen members 62 to the upper and lower sides at different timings.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an impurity removal screen device that transfers impurities contained in sewage upward.

Background Art

[0002] In a sewage treatment system, generally, sewage composed of sewage flows and is purified in the order of a grit chamber, a primary sedimentation tank, a reaction tank, and a final sedimentation tank. Among these, for example, in the primary sedimentation tank, sewage (raw sludge) containing sludge deposited at the bottom of the tank is transferred outside the primary sedimentation tank by a sludge pump or the like, concentrated, dehydrated, and then incinerated. Here, since the raw sludge contains impurities such as scum, generally, before being concentrated and dehydrated, the impurities are removed from the raw sludge by an impurity removal screen device for raw sludge. In addition, sewage (scum water) containing scum of impurities floating near the water surface of the primary sedimentation tank is collected in a scum pit, and then transferred outside the primary sedimentation tank from the scum pit by a scum pump. The scum water transferred outside the primary sedimentation tank is returned to the sewage treatment plant after the scum is removed by a scum removal screen device. These impurity removal screen devices are arranged in a water tank that receives raw sludge and scum water from the primary sedimentation tank (see, for example, Patent Document 1 and Patent Document 2).

[0003] The impurity removal screen device described in Patent Document 1 and Patent Document 2 includes a plurality of fixed screen members and an operating screen member disposed between these plurality of fixed screen members. The fixed screen members each extend obliquely upward, and the uppermost part protrudes from the water surface of the water tank. In addition, the fixed screen members have a stepped shape in which a plurality of fixed step portions are arranged side by side in the extending direction. The operating screen member also extends obliquely upward and has a stepped shape in which a plurality of operating step portions are arranged side by side in the extending direction. The operating screen member transfers impurities toward the uppermost part of the fixed screen member by repeatedly moving upward and downward with respect to the fixed screen member. [[ID= 17]]

Prior Art Documents

[0004] [Patent Document 1] Japanese Patent Publication No. 2014-114574 [Patent Document 2] Japanese Patent Publication No. 2015-017462 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The contaminant removal screen devices described in Patent Documents 1 and 2 transfer contaminants to one level above the fixed step of the fixed screen member by having the movable screen member move upward and downward in one cycle. Therefore, in order to transfer contaminants to the top of the fixed screen member, it is necessary to move the movable screen member many times. However, in recent years there has been a demand for contaminant removal screen devices that can transfer contaminants more efficiently.

[0006] In view of the above circumstances, the present invention aims to provide a contaminant removal screen device that can efficiently transport contaminants. [Means for solving the problem]

[0007] The present invention, which solves the above problems, is a contaminant removal screen device that transports contaminants contained in wastewater upward, Multiple first movable screen members are arranged at intervals in the thickness direction, and each has multiple stepped sections in the direction of transporting impurities, and moves repeatedly upward and downward. A plurality of second movable screen members are arranged between the first movable screen members, and each has multiple steps in the direction of transport of impurities, and moves repeatedly upward and downward. The drive mechanism comprises a first frame to which a plurality of the first movable screen members are fixed, and a second frame to which a plurality of the second movable screen members are fixed. The drive mechanism may be characterized in that it moves the first movable screen member and the second movable screen member upward and downward at different timings by moving the first frame and the second frame.

[0008] Furthermore, in the impurity removal screen device of the present invention, the drive mechanism may be configured to include a common actuator that moves the first movable screen member and the second movable screen member upward and downward, respectively.

[0009] Furthermore, in the impurity removal screen device of the present invention, the first movable screen member and the second movable screen member may be arranged alternately. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a contaminant removal screen device that can efficiently transfer contaminants. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram showing some of the facilities within a sewage treatment plant. [Figure 2] This is a front view of a screen unit for raw sludge equipped with the raw sludge contaminant removal screen device of this embodiment. [Figure 3] Figure 2 is a cross-sectional view (AA) of the screen unit for raw sludge shown in Figure 2. [Figure 4] Figure 2 is a front view of the screen device for removing impurities from raw sludge. [Figure 5] This is a partially enlarged cross-sectional view showing the area around the first and second spacing spacers. [Figure 6] This diagram shows the operation of the first and second operating screen members in a step-by-step manner. [Modes for carrying out the invention]

[0012] Embodiments of the present invention will be described below with reference to the drawings.

[0013] Figure 1 is a schematic diagram showing some of the facilities within a sewage treatment plant. Figure 1 shows a sedimentation tank 1, a screen unit for raw sludge 2, a scum pit 3, and a screen unit for scum 4.

[0014] The sedimentation tank 1 shown in Figure 1 receives wastewater (sewage) from one end in the longitudinal direction (left side in Figure 1), allows the sludge contained in the received wastewater to settle at the bottom of the tank, and drains from the other end (right side in Figure 1). Hereinafter, the left direction in Figure 1 will be referred to as upstream, and the right direction in Figure 1 will be referred to as downstream. A sludge pit 11 is provided at the bottom of the upstream side of the sedimentation tank 1, and a drainage pipe 12 is installed near the water surface on the downstream side. In the sedimentation tank 1, the sludge that has settled at the bottom of the tank is collected in the sludge pit 11 by a sludge scraper (not shown). The sludge collected in the sludge pit 11 is sent by a sludge pump 13 to a raw sludge screen unit 2 installed outside the sedimentation tank 1. The sludge collected in the sludge pit 11 contains impurities such as debris. Hereinafter, the wastewater containing sludge that is sent from the sludge pit 11 to the raw sludge screen unit 2 may be referred to as raw sludge. The raw sludge screen unit 2 is equipped with a raw sludge contaminant removal screen device 6. As will be described in detail later, this raw sludge contaminant removal screen device 6 removes contaminants contained in the raw sludge. The raw sludge from which contaminants have been removed by the raw sludge contaminant removal screen device 6 is then sent to a sludge thickening treatment facility or a sludge dewatering treatment facility. In the sedimentation tank 1, scum floating near the water surface is scraped up to the drainage trough 12 by a scum scraper (not shown). The drainage trough 12 is connected to the scum pit 3, and the wastewater containing scum (scum water) is collected in the scum pit 3 and then sent from the scum pit 3 to the scum screen unit 4 installed outside the sedimentation tank 1 by a scum pump 31. The scum water collected in the scum pit 3 also contains contaminants such as sludge. The scum screen unit 4 is equipped with a scum contaminant removal screen device 7. This scum-removing contaminant screen device 7 removes scum, which is a contaminant contained in the scum water. The wastewater from which the scum has been removed by this scum-removing contaminant screen device 7 is returned to the sewage treatment plant.

[0015] Next, the sludge screen unit 2 provided with the impurity removal screen device 6 for raw sludge will be described as an example. The same applies to the scum screen unit 4 provided with the impurity removal screen device 7 for scum. These impurity removal screen devices 6 for raw sludge and 7 for scum both correspond to an example of an impurity removal screen device. Also, the sludge screen unit 2 and the scum screen unit 4 both correspond to an example of a screen unit.

[0016] FIG. 2 is a front view of the sludge screen unit provided with the impurity removal screen device for raw sludge of the present embodiment. <(

[0017] As shown in FIG. 2, the sludge screen unit 2 includes a water tank 5 and an impurity removal screen device 6 for raw sludge. The sludge screen unit 2 shown in FIG. 2 receives raw sludge from the left side of the figure (see the thick arrow in the figure). Hereinafter, the left side in FIG. 2 is referred to as the upstream side, and the right side is referred to as the downstream side. Also, in FIG. 2, the direction perpendicular to the plane of the paper is referred to as the width direction. The impurity removal screen device 6 for raw sludge includes a screen body 60, which will be described in detail later. In FIG. 2, only the upstream side surface of the screen body 60 is shown by a thick dashed line. <000009l>

[0018] In Figure 2, the lower half of the upstream side wall of the tank 5 has a sloping section 51 that slopes downstream toward the bottom 5a, and the lower half of the downstream side wall has a sloping section 52 that slopes upstream toward the bottom 5a. Therefore, the tank 5 is narrower towards the bottom 5a. This tank 5 receives the sludge collected in the sludge pit 11 shown in Figure 1 as raw sludge. An inlet pipe 53 is provided on the upstream side of the tank 5. Raw sludge is supplied to the inlet pipe 53 by driving the sludge pump 13, flows into the tank 5 from the tip 531 of the inlet pipe 53, and flows downstream (see the numerous thin arrows in the figure). The tip 531 of the inlet pipe 53 is formed in a fan shape that widens toward the downstream when viewed from above. Furthermore, impurities X such as sludge contained in the raw sludge are blocked by a screen body 60 provided by the raw sludge impurity removal screen device 6, and accumulate near the water surface upstream of the screen body 60. The screen body 60 is driven by a motor 654 controlled by a control unit 66. This motor 654 is an example of an actuator. A gearbox 655 is attached to the motor 654. The gearbox 655 is fixed to a mounting base 56 formed at the upper downstream end of the water tank 5.

[0019] The raw sludge screen unit 2 is provided with an emergency overflow unit 54 upstream of the screen body 60 in the raw sludge impurity removal screen device 6. Further, a drainage overflow unit 55 is provided downstream of the screen body 60. Both the emergency overflow unit 54 and the drainage overflow unit 55 have drainage troughs 541, 551 and weir plates 542, 552. These drainage troughs 541, 551 are both provided so as to project outward in the width direction of the water tank 5. The weir plate 552 of the drainage overflow unit 55 is provided at the boundary between the inside of the water tank 5 and the inside of the drainage trough 551, and the inside of the water tank 5 and the inside of the drainage trough 551 are connected at a portion above the weir plate 552 and not connected at a portion below the upper end of the weir plate 552. When the water level of the water tank 5 exceeds the height position of the upper end of the weir plate 552, the sewage in the water tank 5 flows over the weir plate 552 and into the drainage trough 551. The sewage in the water tank 5 here is the raw sludge that has passed through the screen body 60, that is, the sewage containing the sludge from which impurities X have been removed by the raw sludge impurity removal screen device 6, and this sewage is sent to the sludge thickening treatment facility and the sludge dewatering treatment facility, which are facilities in the post-treatment process. Thus, the raw sludge that has passed through the screen body 60 provided in the raw sludge impurity removal screen device 6 is drained outside the raw sludge screen unit 2 by the drainage overflow unit 55.

[0020] The structure of the emergency overflow unit 54 is the same as that of the drainage overflow unit 55, but the emergency overflow unit 54 is provided at a higher position than the drainage overflow unit 55. When the raw sludge impurity removal screen device 6 fails or the water level of the water tank 5 rises from the normal water level and exceeds the weir plate 542 of the emergency overflow unit 54, the raw sludge in the water tank 5 flows into the drainage trough 541 of the emergency overflow unit 54. The raw sludge in the water tank 5 here is the raw sludge before passing through the screen body 60, that is, the sewage containing the sludge before the impurities are removed by the raw sludge impurity removal screen device 6, and this sewage is returned to the upstream end of the raw sludge impurity removal screen device 6.

[0021] Next, the raw sludge contaminant removal screen device 6 will be described. The raw sludge contaminant removal screen device 6 comprises a screen body 60, a base frame 64, a drive mechanism 65, a control unit 66, and a chute 67. The screen body 60 is located inside the base frame 64, and the upper part of the upstream end of the base frame 64 is covered by a front cover 641 with a handle 6411. This front cover 641 is detachable from the base frame 64. The base frame 64 is attached to a pair of support legs 59 fixed to the edge of the water tank 5. Although one of the pair of support legs 59 is shown in Figure 2, the other support leg 59 is fixed to the opposite edge of the water tank 5, sandwiching the raw sludge contaminant removal screen device 6 in the width direction. The base frame 64 is rotatably connected to the support legs 59 by a support shaft 59a and fixed at the angle shown in Figure 2 by bolts (not shown). The configuration of the base frame 64 will be explained in more detail later.

[0022] The screen body 60 is positioned in the water tank 5 at an inclined position, with its lower part facing the upstream side of the water tank 5 and its upper part facing the downstream side. The top of the screen body 60 is positioned above the weir plate 542 of the emergency overflow unit 54. As will be described in more detail later, the screen body 60 moves repeatedly up and down, transporting the contaminants X to the top of the screen body 60. The contaminants X that reach the top of the screen body 60 are then dropped into the chute 67. The chute 67 has an outlet 671 that opens outside the raw sludge contaminant removal screen device 6. The contaminants X dropped into the chute 67 are discharged from its outlet 671.

[0023] Figure 3 is a cross-sectional view of the raw sludge screen unit shown in Figure 2. Figure 4 is a front view of the raw sludge contaminant removal screen device shown in Figure 2. Note that in Figure 3, a portion of the base frame 64 is omitted from the illustration. Also, in Figure 4, the motor 654 and gearbox 655 shown in Figure 2 are omitted from the illustration.

[0024] As shown in Figure 3, the screen body 60 is composed of a plurality of first movable screen members 61 and a plurality of second movable screen members 62. The first movable screen members 61 are arranged at a distance from each other in the width direction, which is the thickness direction, and the second movable screen members 62 are arranged between the first movable screen members 61. In other words, the first movable screen members 61 and the second movable screen members 62 are arranged alternately in their thickness direction. In this embodiment, the number of first movable screen members 61 is one greater than the number of second movable screen members 62. However, the number of first movable screen members 61 and the number of second movable screen members 62 may be the same. Also, the number of first movable screen members 61 may be one less than the number of second movable screen members 62. Each of the first movable screen members 61 and the second movable screen members 62 is an elongated stainless steel member that is inclined to be located downstream as it moves upward. However, the first operating screen member 61 and the second operating screen member 62 may be made of other metals or resins, as long as they have excellent corrosion resistance and durability against raw sludge, and may be made of different materials. The thickness of the first operating screen member 61 and the second operating screen member 62 is 2 mm each. This thickness is set to 2 mm or more and 9 mm or less, depending on the length of the screen member and the characteristics of the impurities to be removed. Also, the spacing W in the width direction between the first operating screen member 61 and the second operating screen member 62 is 2 mm. This spacing W is a gap connecting the upstream and downstream sides, set based on the balance between the flow rate of raw sludge passing through the raw sludge impurity removal screen device 6 and the size of the device, and is set to 0.5 mm or more and 25 mm or less, depending on the characteristics of the impurities to be removed.

[0025] As shown in Figure 4, the first movable screen member 61 is provided with four first spacing spacers 612 that protrude on both sides in the thickness direction, spaced apart in the longitudinal direction. The number of first spacing spacers 612 provided on the first movable screen member 61 can be any number, as long as it is set according to the length of the first movable screen member 61 in the longitudinal direction. The second movable screen member 62 is provided with four second spacing spacers 622 that protrude on both sides in the thickness direction, spaced apart in the longitudinal direction. The number of second spacing spacers 622 provided on the second movable screen member 62 can be any number, as long as it is set according to the length of the second movable screen member 62 in the longitudinal direction. These first spacing spacers 612 and second spacing spacers 622 are examples of spacing members. The gap W between the first movable screen member 61 and the second movable screen member 62 is maintained by these first spacing spacers 612 and second spacing spacers 622, and the fixed uppermost section 63. The configuration of the first spacing spacers 612, second spacing spacers 622, and fixed uppermost section 63 will be described in detail later. Of the impurities X (see Figure 2) contained in the raw sludge, the impurities X that could not pass through the gap W are captured by the screen body 60 by blocking this gap W on the upstream side of the screen body 60. Note that in Figure 3, the first movable screen member 61, the multiple second movable screen members 62, and part of the fixed uppermost section 63 are omitted in order to simplify the drawing. Also, in Figure 3, the thickness of the first movable screen member 61, the multiple second movable screen members 62, and the fixed uppermost section 63, as well as the gap W between the first movable screen member 61 and the second movable screen member 62, are exaggerated.

[0026] On the upstream side of the first operating screen member 61, multiple first-stage sections 611 are provided along the longitudinal direction of the first operating screen member 61. Similarly, on the upstream side of the second operating screen member 62, multiple second-stage sections 621 are provided along the longitudinal direction of the second operating screen member 62. Here, the longitudinal direction of the first operating screen member 61 and the longitudinal direction of the second operating screen member 62 are the transport direction for transferring impurities, as will be described later. That is, both the first operating screen member 61 and the second operating screen member 62 are provided with stepped sections (steps) aligned in the transport direction for impurities. In addition, a fixed uppermost section 63 is provided near the top of both the first operating screen member 61 and the second operating screen member 62. The fixed uppermost section 63 is located above the water surface of the raw sludge. The fixed uppermost section 63 has a comb-like shape, with the tooth portion 631 inserted between the first movable screen member 61 and the second movable screen member 62. The base portion 632 of the fixed uppermost section 63 is stretched between a pair of side frames 642 and is detachably attached to each of the side frames 642 by screws. This fixed uppermost section 63 is intended to scoop up the foreign matter X that has been transported to the uppermost section from the first movable screen member 61 or the second movable screen member and drop it into the chute 67.

[0027] As shown in Figure 3, the base frame 64 includes a pair of side frames 642, a pair of bearings 643, a cross plate (not shown), and a pair of side covers (not shown). The pair of side frames 642 extend along the side walls 5b of the tank 5 from the bottom 5a of the tank 5 to above the top edge of the tank 5, on both ends of the tank 5 in the width direction. The side frames 642 are spaced 450 mm apart in the width direction. The spacing between the side frames 642 can be set according to the size of the tank 5 and the amount of raw sludge sent to the raw sludge screen unit 2, and can be any spacing. The spacing between the side frames 642 in the width direction is appropriately determined according to the processing capacity of the raw sludge impurity removal screen device 6 and the amount and quality of raw sludge flowing into the tank 5. The bearings 643 are fixed to each of the side frames 642. The cross plates are plate-shaped members that extend in the width direction and connect the side frames 642 together. These bearings 643 and cross plates are positioned above the tank 5. A pair of side covers are attached to each of the side frames 642. These side covers are stainless steel plates with rubber seals on their widthwise ends. These side covers seal the space between the upstream ends of the side frames 642 and the side walls 5b of the tank at both widthwise ends of the tank 5. Raw sludge flowing from the upstream side towards the side covers is gathered towards the center in the width direction by the side covers and flows between the pair of side frames 642.

[0028] The drive mechanism 65 comprises a first frame 651, a second frame 652, a drive shaft 653, a motor 654 (see Figure 2), a gearbox 655, and a shaft coupling 656. The first frame 651 comprises a first right frame 651R, a first left frame 651L, and two horizontal members 6511 for the first movable screen. The first right frame 651R and the first left frame 651L are located on the inside in the width direction of the side wall surface 5b of the water tank 5 and on the outside in the width direction of the pair of side frames 642. As shown in Figure 4, the first right frame 651R is a plate-shaped member in which a roughly triangular triangular portion and two arm portions extending downward from the triangular portion are integrally formed. The first left frame 651L is symmetrical with the first right frame 651R with respect to the center of the water tank 5 in the width direction as the plane of symmetry. Furthermore, as shown in Figure 3, the two horizontal members 6511 for the first movable screen are stretched between the first right frame 651R and the first left frame 651L. The widthwise ends of the two horizontal members 6511 for the first movable screen are fixed to the arm portions of the first right frame 651R and the first left frame 651L, respectively. Thus, the two horizontal members 6511 for the first movable screen connect the first right frame 651R and the first left frame 651L. All the first movable screen members 61 are fixed to the upstream sides of the two horizontal members 6511 for the first movable screen, spaced apart from each other in the widthwise direction.

[0029] The second frame 652 comprises a second right frame 652R, a second left frame 652L, and two horizontal members 6521 for the second movable screen. The second right frame 652R and the second left frame 652L are positioned on the inside in the width direction of the side wall surface 5b of the aquarium 5 and on the outside in the width direction of the first right frame 651R and the first left frame 651L. As shown in Figure 4, the second right frame 652R is a plate-like member in which a roughly triangular triangular portion and two arm portions extending downward from the triangular portion are integrally formed. The second left frame 652L has a plane symmetrical shape with respect to the second right frame 652R with respect to the center of the aquarium 5 in the width direction as the plane of symmetry. Also, as shown in Figure 3, the two horizontal members 6521 for the second movable screen are stretched between the second right frame 652R and the second left frame 652L. The two horizontal members 6521 for the second movable screen are fixed at both ends in the width direction to the arm portions of the second right frame 652R and the second left frame 652L, respectively. Thus, the two horizontal members 6521 for the second movable screen connect the second right frame 652R and the second left frame 652L. All the second movable screen members 62 are fixed to the upstream sides of the two horizontal members 6521 for the second movable screen, spaced apart from each other in the width direction.

[0030] The drive shaft 653 is a shaft that extends in the width direction upstream of the screen body 60. The drive shaft 653 passes through each of the pair of side frames 642 and is rotatably supported by the side frames 642 by a pair of bearings 643. One end of the drive shaft 653 is connected to a shaft coupling 656. The output shaft 655a of the gearbox 655 is also connected to the shaft coupling 656. The gearbox 655 converts the driving force (rotational force) and driving direction (direction of rotation) generated by the motor 654 (see Figure 2). The driving force of the motor 654 is transmitted to the drive shaft 653 via the gearbox 655 and the shaft coupling 656, and acts as a force that rotates the drive shaft 653. Alternatively, the motor 654 may be positioned so that the axial direction of the output shaft of the motor 654 coincides with the width direction, and the output shaft of the motor 654 and the drive shaft 653 may be directly connected without using the gearbox 655.

[0031] A first eccentric cam 6531 and a second eccentric cam 6532 are fixed to each end of the drive shaft 653, which are located outside the width direction of the pair of side frames 642. The first eccentric cam 6531 is a thick-walled disc-shaped cam whose center is eccentric with respect to the drive axis 653a, which is the axis of the drive shaft 653. The second eccentric cam 6532 has the same shape as the first eccentric cam 6531. However, the center of the second eccentric cam 6532 is located on the opposite side of the drive axis 653a from the center of the first eccentric cam 6531. In other words, the first eccentric cam 6531 and the second eccentric cam 6532 are fixed at positions that are 180 degrees out of phase with respect to the drive shaft 653 as the center of rotation. The drive shaft 653 rotates around its axis by receiving the rotational force of the motor 654 shown in Figure 2. As a result, the first eccentric cam 6531 and the second eccentric cam 6532 rotate around the drive shaft 653 as the center of rotation, with their orientations offset by 180 degrees when viewed from the width direction.

[0032] The first right frame 651R and the first left frame 651L are rotatably supported on an unillustrated shaft provided on the first eccentric cam 6531. The second right frame 652R and the second left frame 652L are rotatably supported on an unillustrated shaft provided on the second eccentric cam 6532. The shafts provided on the first eccentric cam 6531 and the shafts provided on the second eccentric cam 6532 are equidistant from the drive axis 653a and are positioned 180 degrees offset from the drive axis 653 as the center of rotation. Therefore, when the first eccentric cam 6531 and the second eccentric cam 6532 rotate in response to the rotational force of the motor 654 shown in Figure 2, the first frame 651 and the second frame 652 move in a circular orbit with a 180-degree phase difference when viewed from the width direction. As a result, the first movable screen member 61 and the second movable screen member 62 repeatedly move upward and downward at different timings.

[0033] Figure 5 is a partially enlarged cross-sectional view showing the area around the first and second spacing spacers.

[0034] In Figure 5, the two members with cross-hatching are the first movable screen members 61, and the member with downward-sloping hatching positioned between them is the second movable screen member 62. The first spacing spacer 612 and the second spacing spacer 622 have the same configuration and perform the same function, except that their mounting positions and the objects to which they are mounted differ. In the following description, the configuration and function of the first spacing spacer 612 will be mainly described, and the description of the second spacing spacer 622 will be omitted. The first spacing spacer 612 is a combination of a first male part 612m and a first female part 612f. The first male part 612m has a hemispherical head 612mh, a boss part 612mb protruding from the head 612mh, and a locking part 612ml provided at the protruding end of the boss part 612mb. The boss part 612mb has a protruding length greater than or equal to the thickness of the first movable screen member 61. The boss portion 612mb is inserted into the first mounting hole 61h provided in the first movable screen member 61 and penetrates the first movable screen member 61. The first female portion 612f is hemispherical in shape and has a locking hole 612fh into which the locking portion 612ml of the first male portion 612m fits. The edge portion defining the locking hole 612fh of the first female portion 612f and the locking portion 612ml of the first male portion 612m elastically deform relative to each other when the locking portion 612ml is inserted into the locking hole 612fh. After the locking portion 612ml is inserted into the locking hole 612fh, the locking portion 612ml is locked to the edge portion of the locking hole 612fh, thereby fixing the spacing spacer 6212 to the first movable screen member 61. The head portion 612mh of the first spacing spacer 612 contacts the second movable screen member 62, thereby maintaining the distance W between the first movable screen member 61 to which the first spacing spacer 612 is attached and the second movable screen member 62 to which the head portion 612mh contacts. Similarly, the first female portion 612f of the first spacing spacer 612 contacts the second movable screen member 62, thereby maintaining the distance W between the first movable screen member 61 to which the first spacing spacer 612 is attached and the second movable screen member 62 to which the first female portion 612f contacts. In the same way, the distance W between the first movable screen member 61 and the second movable screen member 62 is also maintained by the second spacing spacer 622.

[0035] Next, the operation of the first operating screen member 61 and the second operating screen member 62 in the raw sludge contaminant removal screen device 6 will be described.

[0036] Figure 6 is a diagram illustrating the stepwise operation of the first and second operating screen members. This Figure 6 shows the first and second operating screen members viewed from the width direction. In Figure 6, the first operating screen member 61 is shown with a thin dashed line to make the operation of the first and second operating screen members 62 easier to understand. In Figure 6, the left side of the diagram is the upstream side, and the right side is the downstream side.

[0037] Figure 6(a1) shows the first movable screen member 61 and the second movable screen member 62 in their home positions. The control unit 66 (see Figure 2) stops the motor 654 (see Figure 2) so that the first movable screen member 61 and the second movable screen member 62 are in their home positions. As a result, when the motor 654 is not being driven, the first movable screen member 61 and the second movable screen member 62 remain in this home position. In the home position, the first stage portion 611 of the first movable screen member 61 and the second stage portion 621 of the second movable screen member 62 are almost overlapping when viewed from the width direction, except for the lowest stage of the first movable screen member 61 and the highest stage of the second movable screen member 62. Also, as shown in Figure 6(a1), foreign matter X is caught from the 11th stage from the bottom of the first movable screen member 61 to the 10th stage from the bottom of the adjacent second movable screen member 62 to the second stage portion 621. In many cases, the foreign matter X is caught across the width direction between multiple first-stage sections 611 and multiple second-stage sections 621. The height position of the first-stage section 611, which is the 11th stage from the bottom of the first movable screen member 61, as shown in Figure 6(a1), and the height position of the second-stage section 621, which is the 10th stage from the bottom of the second movable screen member 62, are approximately the same.

[0038] As described above, when the motor 654 shown in Figure 2 is driven, the drive shaft 653, the first eccentric cam 6531, and the second eccentric cam 6532 shown in Figure 3 rotate, causing the first frame 651 and the second frame 652 to rotate. As the first frame 651 and the second frame 652 rotate, the first movable screen member 61 and the second movable screen member 62 move in a circular orbit when viewed from the width direction, while maintaining the inclination angle when viewed from the width direction. That is, the first movable screen member 61 and the second movable screen member 62 repeatedly move upward and downward, accompanied by movement to the upstream and downstream sides.

[0039] Figure 6(a2) shows the state when the drive shaft 653 has rotated 45 degrees clockwise from the position in Figure 6(a1). As shown in Figure 6(a2), the first movable screen member 61 has moved upstream and upward relative to the position in Figure 6(a1). The impurities X, along with the first movable screen member 61, are also moving upstream and upward on the 11th stage from the bottom, the first stage portion 611. The second movable screen member 62 has moved downstream and downward relative to the position in Figure 6(a1). In other words, in the movement from the position in Figure 6(a1) to the position in Figure 6(a2), the drive mechanism 65 moves the first movable screen member 61 upward while moving the second movable screen member 62 downward.

[0040] Figure 6(a3) shows the state after the drive shaft 653 has rotated another 45 degrees clockwise from the position shown in Figure 6(a2). As shown in Figure 6(a3), the first movable screen member 61 has moved downstream and upward relative to the position shown in Figure 6(a2). The impurities X have also moved downstream and upward along with the first movable screen member 61. The second movable screen member 62 has moved upstream and downward relative to the position shown in Figure 6(a2). In this movement from the position shown in Figure 6(a2) to the position shown in Figure 6(a3), the drive mechanism 65 moves the second movable screen member 62 downward while moving the first movable screen member 61 upward.

[0041] Figure 6(a4) shows the state after the drive shaft 653 has rotated another 45 degrees clockwise from the position shown in Figure 6(a3). As shown in Figure 6(a4), the first movable screen member 61 has moved further downstream and upward from the position shown in Figure 6(a3). The impurities X have also moved further downstream and upward along with the first movable screen member 61. The second movable screen member 62 has also moved further upstream and downward from the position shown in Figure 6(a3). In this movement from the position shown in Figure 6(a3) to the position shown in Figure 6(a4), the drive mechanism 65 moves the second movable screen member 62 downward while moving the first movable screen member 61 upward.

[0042] Figure 6(a5) shows the position after the drive shaft 653 has rotated another 45 degrees clockwise from the position in Figure 6(a4). As shown in Figure 6(a5), the first movable screen member 61 has moved downstream and downward relative to the position in Figure 6(a4). The impurities X have also moved downstream and downward along with the first movable screen member 61. The second movable screen member 62 has moved upstream and upward relative to the position in Figure 6(a4). At the position in Figure 6(a5), the first stage 611 of the first movable screen member 61 and the second stage 621 of the second movable screen member 62 are exactly swapped in the width direction relative to the position in Figure 6(a1). The impurities X have also moved one stage upward relative to the position in Figure 6(a1). In the transition from Figure 6(a4) to Figure 6(a5), the drive mechanism 65 moves the second movable screen member 62 upward while moving the first movable screen member 61 downward.

[0043] Figure 6(a6) shows the state after the drive shaft 653 has rotated another 45 degrees clockwise from the position shown in Figure 6(a5). As shown in Figure 6(a6), the first movable screen member 61 has moved further downstream and downward from the position shown in Figure 6(a5). The second movable screen member 62 has moved upstream and upward from the position shown in Figure 6(a5). The impurities X are then passed from the first stage 611, the 11th stage from the bottom of the first movable screen member 61, to the second stage 621, the 12th stage from the bottom of the second movable screen member 62, and move upstream and upward together with the second movable screen member 62. In this movement from the position shown in Figure 6(a5) to the position shown in Figure 6(a6), the drive mechanism 65 moves the second movable screen member 62 upward while moving the first movable screen member 61 downward.

[0044] Figure 6(a7) shows the state after the drive shaft 653 has rotated another 45 degrees clockwise from the position in Figure 6(a6). As shown in Figure 6(a7), the first movable screen member 61 has moved upstream and downward relative to the position in Figure 6(a6). The second movable screen member 62 has moved downstream and upward relative to the position in Figure 6(a6). The impurities X have moved downstream and upward together with the second movable screen member 62. In this movement from the position in Figure 6(a6) to the position in Figure 6(a7), the drive mechanism 65 moves the second movable screen member 62 upward while moving the first movable screen member 61 downward.

[0045] Figure 6(a8) shows the state after the drive shaft 653 has rotated another 45 degrees clockwise from the position in Figure 6(a7). As shown in Figure 6(a8), the first movable screen member 61 has moved further upstream and downward from the position in Figure 6(a7). The second movable screen member 62 has also moved further downstream and upward from the position in Figure 6(a7). The impurities X have moved downstream and upward together with the second movable screen member 62. In this movement from the position in Figure 6(a7) to the position in Figure 6(a8), the drive mechanism 65 moves the second movable screen member 62 upward while moving the first movable screen member 61 downward.

[0046] When the drive shaft 653 rotates another 45 degrees clockwise in Figure 6 from the position shown in Figure 6(a8), the first movable screen member 61 moves upstream and upward relative to the position shown in Figure 6(a8). The second movable screen member 62 moves downstream and downward relative to the position shown in Figure 6(a8). The impurities X then move downstream and downward together with the second movable screen member 62. As a result, the first movable screen member 61 and the second movable screen member 62 return to the home position shown in Figure 6(a1). The impurities X are then lifted two stages higher at the first stage 611 and the second stage 621 from the position before the drive mechanism 65 started rotating, as shown by the dashed line in Figure 6(a1). In this movement from the position shown in Figure 6(a8) to the position shown in Figure 6(a1), the drive mechanism 65 moves the first movable screen member 61 upward while moving the second movable screen member 62 downward.

[0047] The drive of the screen body 60, which returns to the position in Figure 6(a1) after one rotation of the drive shaft 653 from the position in Figure 6(a1) before the drive shaft 653 rotates, is performed repeatedly for a predetermined operating period, depending on the number of stages of the first operating screen member 61 and the second operating screen member 62, at a speed of, for example, about 13 cycles per minute.

[0048] As described above, during operation, the impurities X captured by the screen body 60 are transported two steps upward with each cycle on the upstream side of the screen body 60, and finally slide down from the uppermost section 63 shown in Figure 4 towards the chute 67, and are discharged outside the raw sludge impurities removal screen device 6.

[0049] According to this embodiment, multiple first movable screen members 61 and second movable screen members 62 are arranged alternately in the thickness direction, and the first movable screen members 61 and second movable screen members 62 are moved upward and downward at different timings, so that the contaminants X can be moved two levels upward in one cycle. In other words, compared to a conventional contaminant removal screen device that combines a fixed screen member and a movable screen member, contaminants X can be transported efficiently at twice the speed. As a result, the operating period of the motor 654 can be shortened, making it possible to save power in the raw sludge contaminant removal screen device 6. Furthermore, even if the total number of first movable screen members 61 and second movable screen members 62 is halved, for example, to half the total number of fixed screen members and movable screen members in a conventional contaminant removal screen device, the same transport capacity as before can be obtained, so the width direction of the part in which the screen body 60 is arranged can be narrowed, and the raw sludge contaminant removal screen device 6 can be made smaller. As a result, the water tank 5 can also be made smaller, allowing for a smaller raw sludge screen unit 2. Furthermore, since a common motor 654 is used to move the first operating screen member 61 and the second operating screen member 62 upward and downward at different timings, when one of the first operating screen member 61 or the second operating screen member 62 is moving upward and the other is moving downward, the load due to the weights of the first operating screen member 61 and the second operating screen member 62 cancel each other out, thus reducing the load on the motor 654. This also contributes to power saving in the raw sludge contaminant removal screen device 6. In addition, the load on the drive mechanism 65 is reduced, increasing the durability of the drive mechanism 65. Furthermore, the fluctuations in the load due to the weights of the first operating screen member 61 and the second operating screen member 62 in one cycle are reduced, resulting in smoother rotation and suppressing vibrations in the raw sludge contaminant removal screen device 6. Furthermore, in this embodiment, the drive mechanism 65 moves the second movable screen member 62 downward when the first movable screen member 61 is moving upward, and moves the first movable screen member 61 downward when the second movable screen member 62 is moving upward.Therefore, the weight of the first operating screen member 61 and the weight of the second operating screen member 62 can be almost completely offset, further reducing the load on the drive mechanism 65. In other words, when one of the first operating screen member 61 or the second operating screen member 62 is moving upward, the weight of the other acts as an assisting force in driving the drive mechanism 65, thus greatly reducing the load on the drive mechanism 65. As a result, the raw sludge contaminant removal screen device 6 can be driven with less power. In addition, since the balance of the load on the drive mechanism 65 due to the weights of the first operating screen member 61 and the second operating screen member 62 becomes almost uniform, the rotational movement of the drive mechanism 65 becomes smoother, and vibrations caused by driving are further reduced. Furthermore, since the first operating screen member 61 and the second operating screen member 62 are arranged alternately and the conventionally provided fixed screen member is omitted, the raw sludge contaminant removal screen device 6 can be made more compact. In addition, the gap W between the first movable screen member 61 and the second movable screen member 62 is maintained by the first spacing spacer 612 and the second spacing spacer 622, so that the gap W between the first movable screen member 61 and the second movable screen member 62 can be maintained at a constant interval. Furthermore, it is possible to reliably prevent the first movable screen member 61 and the second movable screen member 62 from coming into contact with each other.

[0050] The present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the claims. For example, in the embodiments described above, a raw sludge contaminant removal screen device 6 provided in the raw sludge screen unit 2 and a scum contaminant removal screen device 7 provided in the scum screen unit 4 were used as examples, but the present invention can be applied not only to sewage treatment facilities but also to facilities that treat water such as industrial water and agricultural water. Furthermore, in the embodiments described above, a contaminant removal screen device installed in the water tank 5 was used as an example, but the contaminant removal screen device may be installed in the wastewater flowing through the flow path. In addition, the drive mechanism 65 was described as moving the first operating screen member 61 and the second operating screen member 62 in a circular orbit when viewed from the width direction, but it may be configured to perform polygonal movement such as rectangular movement or elliptical movement using a link mechanism or the like. Furthermore, in this embodiment, the screen body 60 is composed of two parts, a first movable screen member 61 and a second movable screen member 62. However, it may also be composed of three or more movable screen members that move at different timings. In this case, it is preferable to arrange multiple sets of these sets in the thickness direction, with each movable screen member moving at a different timing arranged one by one in the thickness direction. In this case, it is preferable to set the timing for moving each movable screen member upward so that the drive load of the drive mechanism 65 is uniform within one cycle, taking into account the total weight of the frame that drives the movable screen members and the movable screen members attached to that frame. This enhances the power consumption reduction effect and vibration suppression effect. In addition, fixed screen members that are fixed to the base frame 64 and do not move may be placed between the first movable screen member 61 and the second movable screen member 62. In this case, the distance between the first movable screen member 61 and the fixed screen member, and the distance between the second movable screen member 62 and the fixed screen member, are set to 0.5 mm or more and 25 mm or less, respectively, depending on the characteristics of the contaminants to be removed. Furthermore, a gap-reducing member may be provided at the lowest stage of the first movable screen member 61, which protrudes in the thickness direction and reduces the gap in the thickness direction.This prevents foreign matter X from slipping downstream through the gap in the thickness direction at the lowest stage of the first movable screen members 61 when the screen body 60 is in the home position shown in Figure 6(a1). Furthermore, at least one of the first spacing spacer 612 and the second spacing spacer 622 may be omitted.

[0051] Furthermore, even if a constituent element is included only in the description of each of the modified examples described above, that constituent element may be applied to other modified examples.

[0052] The contaminant removal screen device described above is a contaminant removal screen device that transports contaminants contained in wastewater upwards, Multiple first movable screen members are arranged at intervals in the thickness direction, and each has multiple stepped sections in the direction of transporting impurities, and moves repeatedly upward and downward. The system comprises a plurality of second movable screen members, which are arranged between the first movable screen members and have a plurality of steps in the direction of transport of impurities, and which move repeatedly upward and downward, The first movable screen member moves upward and downward at a different timing than the second movable screen member. The first movable screen member and the second movable screen member are arranged alternately without a fixed screen member being placed between them.

[0053] Furthermore, in a contaminant removal screen device that transports contaminants contained in wastewater upward, Multiple first movable screen members are arranged at intervals in the thickness direction, and each has multiple stepped sections in the direction of transporting impurities, and moves repeatedly upward and downward. The system comprises a plurality of second movable screen members, which are arranged between the first movable screen members and have a plurality of steps in the direction of transport of impurities, and which move repeatedly upward and downward, The first movable screen member may be characterized by moving upward and downward at different timings than the second movable screen member.

[0054] With this impurity removal screen device, the first and second movable screen members each transport impurities upward, so impurities can be transported efficiently.

[0055] Here, the first movable screen member may move upward when the second movable screen member is moving downward, and move downward when the second movable screen member is moving upward. Also, the first movable screen member and the second movable screen member may each move in a circular orbit. Furthermore, if the stepped portion provided on the first movable screen member is designated as the first step and the stepped portion provided on the second movable screen member is designated as the second step, the first movable screen member may transfer impurities from the first step to the second step above the first step, and the second movable screen member may transfer impurities from the second step to the first step above the second step.

[0056] Furthermore, this impurity removal screen device may also be provided with a common actuator for moving the first movable screen member and the second movable screen member upward and downward, respectively.

[0057] According to this embodiment, when one of the first and second movable screen members moves upward and the other moves downward, the weight of the first movable screen member and the weight of the second movable screen member cancel each other out, thus enabling power saving of this contaminant removal screen device. Furthermore, since there is no need to add the actuator, this contaminant removal screen device can be constructed at a low cost.

[0058] Furthermore, in this impurity removal screen device, the first operating screen member and the second operating screen member may be arranged alternately.

[0059] This allows for the omission of fixed screen components, thereby miniaturizing the impurity removal screen device.

[0060] In addition, this impurity removal screen device may be provided with a spacing maintenance member that maintains the distance between the first movable screen member and the second movable screen member.

[0061] The spacing maintenance member ensures that the distance between the first and second movable screen members is maintained at a constant distance. Furthermore, it reliably prevents the first and second movable screen members from coming into contact.

[0062] Here, the spacing maintenance member may be detachably attached to the first or second movable screen member and be replaceable. Furthermore, the spacing maintenance member may be made of resin. [Explanation of symbols]

[0063] 6. Screening device for removing impurities from raw sludge (impurity removal screening device) 61 First Operating Screen Member 62 Second Operating Screen Member 611 First Section 621 Section 2 X Miscellaneous

Claims

1. In a contaminant removal screen device that transports contaminants contained in wastewater upward, Multiple first movable screen members are arranged at intervals in the thickness direction, and each has multiple stepped sections in the direction of transporting impurities, and moves repeatedly upward and downward. A plurality of second movable screen members are arranged between the first movable screen members, and are provided with a plurality of steps in the direction of transfer of impurities, and move repeatedly upward and downward. The drive mechanism comprises a first frame to which a plurality of the first movable screen members are fixed, and a second frame to which a plurality of the second movable screen members are fixed. The impurity removal screen device is characterized in that the drive mechanism moves the first and second frames to move the first movable screen member and the second movable screen member upward and downward at different timings.

2. The impurity removal screen device according to claim 1, characterized in that the drive mechanism includes a common actuator for moving the first movable screen member and the second movable screen member upward and downward, respectively.

3. The impurity removal screen device according to claim 1 or 2, characterized in that the first operating screen member and the second operating screen member are arranged alternately.

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