Filtering material washing device

Abstract

To provide a filtering material washing device that rubs and washes a filtering material arranged inside a filter tank or the like by a rotary screw put therein, which is formed to be light at low cost.SOLUTION: Provided is a filtering material washing device 200 for a filtering device 100 which has a layer of a filtering material 110 inside a filtering tank 106 or the like and performs filtering by passing supplied raw water through the layer of the filtering material 110. The filtering material washing device 200 has a spiral screw 204 erected and arranged in the layer of the filtering material 110 and screw driving means 206 and 208 rotating the screw 204 around a screw shaft, and rubs and washes the filtering material 110 by rotating the screw 204, wherein the filtering material 110 is transferred upward while making an outer peripheral edge of the screw 204 having a plurality of screw blade parts directly contact the layer of the filtering material 110 after removing an external cylinder surrounding the screw 204.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a device for cleaning a filter medium in a filtration device that purifies raw water by passing it through the filter medium. [Background technology]

[0002] Conventionally, as shown in Patent Documents 1 and 2, for example, raw water is filtered. past Filtration devices that purify water by using a filter are known. These filtration devices basically have a layer of filter material inside a filter tank made of metal or the like, and raw water is filtered by passing it through the layer of filter material. With repeated use of this type of filtration device, the filter material becomes dirty with captured fine suspended matter, etc., and therefore the filter material must be disposed of or cleaned as appropriate. Conventionally, methods widely used to clean this filter material include surface cleaning, in which a water stream sprayed from a nozzle hits the surface of the filter material layer, and backflow cleaning, in which purified water is forced into the filter material layer from below to knead and clean the filter material.

[0003] However, the surface washing and backwashing methods described above have been recognized to have problems, such as requiring a long time for cleaning due to their weak cleaning effects. Therefore, the present applicant has previously proposed and put into practical use a filter media cleaning device that uses a screw conveyor, as shown in the above-mentioned Patent Documents 1 and 2, for example, as a filter media cleaning device that can solve the above-mentioned problems. This filter media cleaning device basically has a spiral screw (more specifically, a screw blade) arranged upright within the layer of filter media, and a screw drive means that rotates this screw around the screw axis, and by rotating the screw, the filter media is transported from bottom to top, kneading and cleaning it.

[0004] Here, the filter media cleaning device using the screw conveyor is described in detail with reference to FIG. 6, taking the device disclosed in Patent Document 1 as an example. First, a filter device 1 equipped with this filter media cleaning device 14 will be described. Note that the figure also shows some schematic representations, such as the cross-sectional shape of thick components being indicated by a single line. As shown in the schematic side view of the figure, the filter device 1 comprises a substantially cylindrical filter tank 2 closed at the top and bottom, a filter bed 4 with numerous micropores (not shown) located at the bottom inside the filter tank 2, and a filter media 6 stacked on the filter bed 4. The filter tank 2 is fitted with multiple support legs 8 (only one is shown in the figure), which allow the filter tank 2 to be placed on a floor surface 10. The filter bed 4 is fitted with multiple short cylindrical filters 12 made of ceramic with micropores. The filters 12 allow only purified water 16 to permeate downward through the filter bed 4.

[0005] A circular mounting opening 22 is formed in the center of the filter tank upper wall 20, and the filter media cleaning device 14 is attached to this mounting opening 22. The periphery of the mounting opening 22 is formed into a mounting rim 24. A base 28, to which a motor 26 and a speed reduction mechanism 27 are attached, is attached on the rim 24. A holding section 36 having bearings 30 in three locations is formed on this base 28, and these three bearings 30 are configured to support the rotating shaft 34 of the screw conveyor 32 so that it can rotate freely and without wobble.

[0006] In the filter media cleaning device 14, a cylindrical tubular member 38 constituting the cleaning tank body has a disk-shaped partition wall 29 at its top. A flange 31 on the outer periphery of the partition wall 29 is attached to the rim 24, and is attached to the rim 24 together with the base 28 with bolts. In this way, the top of the tubular member 38 is attached to the rim 24, and substantially the entire tubular member 38 hangs down from the upper wall 20. A hole 33 is formed in the center of the flange 31, into which the retaining portion 36 is tightly fitted. This makes it possible to maintain a sealed state inside the filter tank 2 during filtration.

[0007] The lower part of the cylindrical member 38 is an open circular lower opening 40, and the upper part has multiple upper openings 42 formed therein. The multiple upper openings 42 are formed at predetermined intervals around the circumference of the cylindrical member 38 and each extends in the vertical direction. The position of the lower opening 40 relative to the filter material 6 is determined so that it is located within the filter material 6. The screw conveyor 32 is disposed inside the cylindrical member 38. The screw conveyor 32 is formed from a rotating shaft 34, for example, in the form of a hollow pipe, whose upper and lower parts have different diameters, and a helical screw blade portion 43 fixed to the outer peripheral surface of the lower part (relatively large diameter portion) of the rotating shaft 34. The screw blade portion 43 is formed all the way up to the lower end 44 of the rotating shaft 34.

[0008] The upper end of the rotating shaft 34 of the screw conveyor 32 is connected to the speed reducer mechanism 27 of the motor 26 via a joint 52. When the screw blade portion 43 is disposed in the tubular member 38 in this manner, the upper end of the screw blade portion 43 is located near the lower edge 42a of the upper opening 42. Furthermore, the lower end 35 of the screw conveyor 32 protrudes downward from the lower opening 40 of the tubular member 38, and the lower end 44 of the rotating shaft 34 is located near the filter bed 4. Therefore, when the filter media 6 is washed, the filter media 6 near the filter bed 4 is also efficiently transported upward by the screw blade portion 43 and washed.

[0009] A purified water discharge pipe 60 extending downward is attached to the center of the curved bottom wall 58 of the filtration tank 2, and water that has passed through the filter material 6, filter bed 4, and filter 12 and been purified is discharged through this purified water discharge pipe 60. Also, on the right side of the filtration tank 2 in the drawing, there is a raw water inlet (turbidity discharge means) 62, through which raw water, i.e., water before filtration 16, is injected into the filtration tank 2 during filtration, and a water level adjustment port 64 installed below it. The water level adjustment port 64 also functions as a discharge port through which water 16 is discharged in order to adjust the water level to an optimum level for washing the filtration material 6.

[0010] An inspection hatch 68 is provided on the top wall 20 of the filter tank 2, and is used to check the condition inside the filter tank 2, such as the top surface 66 of the filter material 6. An air vent valve 70 is located to the left of the top wall 20 of the filter tank 2. In addition, a filter material insertion port 72 for inserting the filter material 6 is provided on the side of the filter tank 2.

[0011] Next, we will explain filtration and cleaning of the filter material in the filter tank 2. First, raw water to be filtered is pumped into the raw water inlet 62 by a pump (not shown). As the water level 74 rises, air in the filter tank 2 is expelled through the air vent valve 70. The water level 74 ,original The water is set so that it passes through the water inlet 62 and reaches the top of the filter tank 2, that is, so that the filter tank 2 is almost entirely filled with water (raw water) 16. 6 The water level 74 shown in the figure indicates an intermediate position before the tank is full. The water 16 permeates the filter material 6 and also enters the tubular member 38 through the upper opening 42 to permeate the filter material 6 inside the tubular member 38, allowing filtration to occur within the tubular member 38. The water that has permeated the filter material 6 and been filtered is discharged to the outside through the purified water discharge pipe 60 at the bottom of the filter tank 2 and is available for use.

[0012] Next, a method for cleaning the filter media 6 using the filter media cleaning device 14 when the filter media 6 becomes clogged after long-term use will be described. When the motor 26 is driven and the screw conveyor 32 rotates, the blades 43 of the screw conveyor 32, particularly the blades 43 on the portion exposed at the bottom of the tubular member 38, push the filter media 6 upward into the tubular member 38. The particles of the pushed-up filter media 6 rub against each other as the blades 43 rotate, kneading and washing them as they rise, and are then discharged from the upper opening 42 into the filter tank 2. The impact of the filter media 6 falling onto the surface of the water 16 promotes the separation of turbidity from the filter media 6. The dropped filter media 6 is again pushed up into the tubular member 38 by the blades 43 and kneaded and washed. In this way, the filter media 6 is repeatedly cleaned within the tubular member 38, and contaminants are separated. As described above, the lower end 44 of the screw conveyor 32 is located near the filter bed 4, so that the filter media 6 close to the filter bed 4 are also pushed up, and all the filter media 6 are washed evenly.

[0013] The above-mentioned filter media cleaning device has the effect of efficiently cleaning dirty filter media in a short time of about 7 minutes, compared to the 15 minutes required for conventional surface cleaning or backflow cleaning. The above description has been made on the application of the filter media cleaning device to a filtration tank, but filtration basins such as those shown in Patent Document 3 are also well known, and the above-mentioned filter media cleaning device can also be applied to such basins, and in this case too, the filter media can be efficiently cleaned in a short time. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-121885 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-160432 [Patent Document 3] Japanese Patent Application Laid-Open No. 2000-350994 Summary of the Invention [Problem to be solved by the invention]

[0015] In constructing the above-mentioned screw conveyor, it has been conventionally considered necessary to provide a cylindrical member (outer cylinder) that surrounds the screw from the outside and extends in the axial direction of the screw. This cylindrical member must be precisely formed so that its inner circumferential surface maintains a predetermined distance from the outer circumferential edge of the screw, and it must also be made sturdy enough to withstand friction with the transported filter media. For these reasons, conventional filter media cleaning devices that use screw conveyors have room for improvement in terms of cost and weight reduction. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a filter media cleaning device that can be formed at low cost and lightweight. [Means for solving the problem]

[0016] The filter cleaning device according to the present invention comprises: A filter cleaning device for a filtration device that has a layer of filter material inside a filtration tank or filtration basin and filters supplied raw water by passing it through the layer of filter material, A filter material cleaning device having a spiral screw disposed upright within a layer of filter material and a screw driving means for rotating the screw around a screw axis, wherein the filter material is kneaded and washed by rotating the screw, The screw used is a screw in which the spiral screw flight portion constituting the screw is a plurality of screw flight portions that are not continuous with each other and are arranged apart from each other in the screw axial direction, The filter is transported upward while the outer periphery of the screw is in direct contact with the layer of filter material.

[0017] The phrase "while the outer peripheral edge of the screw is in direct contact with the layer of filter material" means that a cylindrical member is not present around the outer periphery of the screw and the filter material that has entered between the cylindrical member and the screw does not come into contact with the outer peripheral edge of the screw; in other words, the aforementioned cylindrical member is not provided. It is most desirable that the range where no cylindrical member is provided extends over the entire length of the screw. However, this is not a limitation, and the cylindrical member may be provided only in a partial range within the entire length of the screw.

[0018] In the filter media cleaning device of the present invention having the above-mentioned configuration, the screw arranged upright in the layer of filter media is most preferably arranged upright in the vertical direction, but is not limited to this and may be arranged at a slight angle inclined to the vertical direction. In this case, the angle of inclination is preferably at most about 10 degrees.

[0019] In the filter media cleaning device of the present invention having the above-mentioned configuration, it is preferable that the screw used be a screw having a coil spring shape. More specifically, this "coil spring shape" refers to a shape in which the helical screw blades constituting the screw form a ring at a position spaced apart from the screw axis when viewed from the screw axial direction (the direction in which the screw axis extends). [Effects of the Invention]

[0020] The inventors discovered for the first time that when a rotating screw transports a filter material upward while kneading and washing the filter material, the filter material can be transported and washed without the need for the aforementioned tubular member. Based on this finding, the filter material washing device of the present invention eliminates the tubular member, thereby ensuring the same filter material washing effect as conventional devices, while allowing for a lower cost and lighter weight due to the omission of the tubular member. This effect is most pronounced when the area without the tubular member extends along the entire length of the screw. Furthermore, the filter material cleaning device according to the present invention uses a screw in which the spiral screw blade portion constituting the screw is a plurality of screw blade portions that are not continuous with each other but are arranged apart from each other in the screw axial direction. Therefore, compared to when a screw with a single screw blade portion is used, a larger amount of filter material can be transported, resulting in higher filter material cleaning efficiency. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a schematic side view showing a filtration device having a filter media cleaning device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a plan view showing a part of the filter cleaning device of FIG. 1; [Figure 3] FIG. 1 is a schematic side view showing a filtration device having a filter media cleaning device as a comparative example of the present invention. [Figure 4] Photograph showing filter media cleaned by the filter media cleaning device of Figure 1 [Figure 5]Photograph showing filter media cleaned by the filter media cleaning device of Figure 3 [Figure 6] 1 is a schematic side view showing a filtration device having a conventional filter media cleaning device; [Figure 7] 1 is a schematic side view showing another example of a filtration device using a filtration media cleaning device according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic side view of a filtration device 100 having a filter media cleaning device according to one embodiment of the present invention. Note that the figure also shows some schematic representations, such as the cross-sectional shapes of thick members being indicated by single lines. First, the filtration device 100 will be described. As shown in the schematic side view of the figure, the filtration device 100 includes a substantially cylindrical filtration tank 106 having an upper end member 102 surrounding a circular opening and a bottom wall 104, a filter bed 108 with numerous micropores (not shown) disposed at the bottom inside the filtration tank 106, and a filter media 110 layered on the filter bed 108, the filter media 110 being made of sand or the like having a specific gravity greater than that of water. The filter bed 108 is provided with a plurality of short cylindrical strainers 112 made of ceramic or the like with micropores.

[0023] As an example, this filtration device 100 is a so-called upflow filtration device, and has a raw water inlet chamber 114 between the filter bed 108 and the bottom wall 104 inside the filtration tank 106. Connected to this raw water inlet chamber 114 are a raw water inlet pipe 115 that opens at a position close to the peripheral wall on the left side of the figure, and a backwash water inlet pipe 116 that opens at a position close to the peripheral wall on the right side of the figure. Meanwhile, connected to the filtration tank 106 at a position slightly below the upper end member 102 is a treated water outlet pipe 118 that communicates with the interior of the filtration tank 106. Also connected to the filtration tank 106 is a filter material outlet 120 that opens into the interior of the filtration tank 106 at a position slightly above the filter bed 108. The filtration device 100 is also provided with a horizontal cleaning port pipe that opens into the raw water inlet chamber 114, a water level adjustment outlet pipe that connects to the cleaning port pipe from above, and other components, but these are not directly related to the present invention and can be formed in the same way as in conventional devices, so they will not be shown in the figures or described in detail. A filter media cleaning device 200 according to one embodiment of the present invention is attached to the center of the filtration tank 106. Details of this filter media cleaning device 200 will be described later.

[0024] In this filtration device 100, raw water to be filtered is sent from a raw water inlet pipe 115 into a raw water inlet chamber 114 under a predetermined pressure. The raw water passes through a plurality of strainers 112 and then passes through a layer of filter media 110 from bottom to top. During this process, contaminants contained in the raw water are absorbed by the filter media. 110 The filtered treated water 122 overflows the weir plate 124 and is discharged from the filtration tank 106 through the treated water outlet pipe 118.

[0025] Next, the filter media cleaning device 200 will be described. The filter media cleaning device 200 has a rotating shaft 203 extending vertically through the center of the filter tank 106, and a spiral screw blade 204 fixed to the outer circumferential surface of the rotating shaft 203. The rotating shaft 203 is composed of an upper shaft portion 201 with a relatively small diameter and a lower shaft portion 202 with a relatively large diameter, and the screw blade 204 is specifically fixed to the outer circumferential surface of the lower shaft portion 202. The rotating shaft 203 and the screw blade 204 form a screw conveyor. Note that in this embodiment, the screw blade 204 is composed of two screw blades that are not continuous with each other and are spaced apart from each other in the screw axial direction.

[0026] A motor 206 and a speed reduction mechanism 208 that reduces the rotation speed of the motor 206 are disposed above the filter tank 106. The motor 206 and speed reduction mechanism 208 constitute a screw drive means, and an output shaft 208a of the speed reduction mechanism 208 is connected to an upper shaft portion 201 of the rotating shaft 203 via a joint 210. The motor 206 and speed reduction mechanism 208 are integrated and held on a holding member 212. The holding member 212 is fixed to the filter tank 106 via a plurality of supports 214 extending in the vertical direction and a support 216 fixed to the inside of the upper part of the filter tank 106. With the above configuration, a screw conveyor consisting of the rotating shaft 203 and the screw blade portion 204 is suspended within the filter material 110 at the center of the filter tank 106.

[0027] The shaft upper portion 201 of the rotating shaft 203 is rotatably supported by, for example, four bearings 218 arranged at intervals in the axial direction. This allows the rotating shaft 203 to rotate without wobbling. Inside the filtration tank 106, one set of filter material flow prevention plates 220 is provided, the planar cross section of which is shown in FIG. 2, surrounding the screw blade portion 204 from eight positions on the outer periphery. These filter material flow prevention plates 220 are provided in, for example, three sets at intervals in the direction in which the spiral of the screw blade portion 204 repeats, i.e., in the axial direction of the rotating shaft 203. Each filter material flow prevention plate 220 is inclined with respect to the axial direction, with the inclination directions opposite to each other in adjacent sets.

[0028] Next, the operation of the filter media cleaning device 200 will be described. As described above, when raw water passes through the filter media 110 and is filtered, contaminants contained in the raw water are captured by the filter media 110. Therefore, in order to continue using the filter media 110 without discarding it, it is necessary to remove the contaminants from the filter media 110, that is, to periodically clean the filter media 110. As one method of cleaning the filter media, the filtration device 100 of this example performs so-called backflow cleaning (backwashing). When performing this backwashing, purified water as backwash water is sent under a predetermined pressure from the backwash water inlet pipe 116 into the raw water inlet chamber 114 during a period when raw water filtration is suspended. This purified water passes from bottom to top through the filter media 110 and is discharged from the filtration tank 106 through the treated water outlet pipe 118. At this time, the contaminants captured by the filter material 110 are removed from the filter material 110 by the purified water and are discharged together with the purified water from the treated water outlet pipe 118 to the outside of the filter tank 106 .

[0029] In addition to this backwashing, cleaning of the filter media can also be performed as appropriate using a filter media cleaning device 200. When cleaning the filter media using this filter media cleaning device 200, the motor 206 is driven during the period when the filtration of raw water is stopped and the backwashing is being performed, and the rotational force is transmitted to the rotating shaft 203 of the screw conveyor via a speed reducer mechanism 208. When the rotating shaft 203 rotates in this manner, the helical screw blade portion 204 rotates, and the filter media 110 are transported upward by the screw blade portion 204. During this process, the individual filter media 110 rub against each other, causing the captured contaminants to be torn off from the filter media 110. In this case, the contaminants are discharged together with the backwash water from the treated water outlet pipe 118 to the outside of the filtration tank 106.

[0030] Unlike conventional screw conveyors that perform kneading and washing of the filter material, this embodiment does not have a tubular member (outer cylinder) surrounding the screw blade portion 204 from the outside. Therefore, in this embodiment, the outer periphery of the screw, or more specifically, the outer periphery of the screw blade portion 204, is kneaded and washed while being brought into direct contact with the layer of filter material 110. In other words, unlike conventional devices, where a tubular member is present outside the periphery of the screw blade portion 204 and the filter material 110 that has entered between the tubular member and the screw comes into contact with the outer periphery of the screw blade portion 204.

[0031] According to the inventor's research, even if the above-mentioned cylindrical member is not provided, the screw blade portion 204 functions as a component of the screw conveyor, and the filter media 110 can be kneaded and washed while being transported upward by the rotating screw blade portion 204. This function is believed to be achieved as follows.

[0032] As the screw blade 204 continues to rotate within the layer of filter material 110, the portion of the filter material 110 in contact with its outer periphery is scraped away, creating a roughly cylindrical space within the layer of filter material 110. In other words, the screw blade 204 rotates within the space with its outer periphery facing the circumferential surface of the space. If the filter material 110 is primarily composed of sand, the circumferential surface of the space becomes a wall, which could be called a "sand wall," and functions similarly to the cylindrical member (outer cylinder) in a conventional device. Therefore, even the filter material 110 scattered outward by the centrifugal force generated by the rotation of the screw blade 204 bounces off this "sand wall" and returns to the upper surface of the screw blade 204, where it is transported upward by the screw blade 204 and kneaded.

[0033] It should be noted that although the peripheral surface of the space (the space in which the screw blade portion 204 rotates) functions like the cylindrical member (external cylinder) in the conventional device as described above, it is ultimately formed from the sand-like filter material 110, and therefore also exhibits the properties inherent to sand-like materials. That is, even if the filter material 110 scattered around the outer periphery of the screw blade portion 204 collides with this peripheral surface as described above, the peripheral surface is only slightly deformed, and the scattered filter material 110 is not crushed. In contrast, in a conventional device in which a cylindrical member (external cylinder) is disposed so as to surround the screw blade portion from the outer periphery, the filter material scattered around the outer periphery from the screw blade portion may collide with the cylindrical member made of metal or the like and be crushed.

[0034] By eliminating the tubular member provided in conventional devices, the filter media cleaning device 200 of this embodiment can be made lower cost and lighter than conventional devices. In particular, the tubular member is typically made of a metal such as stainless steel, and the distance between the tubular member and the screw blade must be precisely set to a predetermined value to prevent the filter media being rubbed and cleaned from being pinched between the inner surface of the tubular member and the screw blade, which tends to increase costs. Eliminating such a tubular member would significantly reduce costs. Furthermore, if the filter media cleaning device 200 can be made lightweight, the filtration device 100 equipped with it can also be made lighter.

[0035] Furthermore, if the weight can be reduced by omitting the above-mentioned cylindrical member, which is usually made of metal, then when there is a weight limit on the screw conveyor, the overall length of the rotating shaft 203 and screw blade portion 204, which together with the cylindrical member constitute the screw conveyor, can also be set to be longer, which is advantageous in forming a longer filter tank 106.

[0036] In addition, in this embodiment, three sets of filter media flow prevention plates 220 are provided to surround the screw blade portion 204 from eight locations on the periphery, thereby achieving the following effect. Specifically, as raw water containing turbidity (pollutants) continues to be filtered through the filter media layer (layer of filter media 110), the turbidity gradually clogs the layer from the bottom, applying pressure to the filter media layer during filtration. As clogging progresses and the filtration pressure increases, the filter media 110 and the turbidity at the bottom of the layer become integrated, further increasing the filtration pressure. Then, as the clumps of filter media 110 and the turbidity rise, a space (a space filled with water) is created in the filter media layer. Eventually, the floating filter media 110 and the turbidity break down and flow, causing the turbidity to leak. This prevents proper filtration, leading to the undesirable release of the turbidity all at once into the filtered treated water 122. On the other hand, if a plurality of sets of filter medium flow prevention plates 220 are provided, the flow and floating of the filter medium 110 can be prevented, and the occurrence of the above-mentioned inconvenience can be avoided.

[0037] Here, a filter material cleaning device 300 as a comparative example of the present invention will be described with reference to Fig. 3. This filter material cleaning device 300 has two screw blades 204 in the filter material cleaning device 200 of the above embodiment. vinegar In the previous example, the screw blade 304 is made up of a single blade. vinegarThe only difference between the filter element cleaning device 300 and the filter element cleaning device 200 is that it is composed of a clew blade portion. The filter element cleaning device 300 is provided inside the filter element 150, and the filter element 150 also differs from the filter element 100 of Figure 1 in that the filter element cleaning device 300 is used instead of the filter element cleaning device 200. Therefore, in Figure 3, the same elements as those in Figure 1 are assigned the same numbers as in Figure 1, and their explanation will be omitted unless particularly necessary.

[0038] In this comparative example, the filter 110 is cleaned in the same manner as in the filter cleaning device 200 of the embodiment shown in Fig. 1. However, in the filter cleaning device 200 of the embodiment, the screw blade portion 204 is made of two blades. vinegar Since the filter 110 is composed of a screw blade portion, the transfer and cleaning of the filter 110 can be performed relatively efficiently. vinegar Because the filter media cleaning device of the present invention is composed of a screw with multiple screw blades, the efficiency of transporting and cleaning the filter media 110 is lower than in the previous embodiment. This clearly shows the advantage of using a screw with multiple screw blades in the filter media cleaning device of the present invention. The photographs shown in Figures 4 and 5 show the actual state of the filter media 110 transported by the screw blades 204 and 304, respectively.

[0039] In the filter cleaning device 200 of the above embodiment, the screw blade portion 204 is vinegar It consists of a clew blade, but has three or more blades. vinegar A clew blade may be applied. vinegar By applying the clew blade, one vinegar This is advantageous in improving the efficiency of transport and cleaning of the filter medium 110 compared to when a clew blade portion is used.

[0040] Although the above has described an embodiment of a filter cleaning device installed in a filtration system having a filtration tank, the filter cleaning device of the present invention is not limited to such a filtration system and can also be installed in a filtration basin. Furthermore, although the filter cleaning devices 200 and 300 described above are applied to an upflow type filtration system, the filter cleaning device of the present invention is not limited to this and can also be applied to a downflow type filtration system as shown in Figure 6.

[0041] Next, with reference to Figure 7, another example of a filtration device in which the filter media cleaning device of the present invention is used will be described. In Figure 7, elements equivalent to those in Figure 1 described above are numbered the same as in Figure 1, and their description will be omitted unless particularly necessary. The filtration device 400 shown in Figure 7 differs from the filtration device 100 shown in Figure 1 in that the shape of the filter bed 108A is fundamentally different. That is, while the filtration device 100 in Figure 1 uses a simple circular filter bed 108, the filter bed 108A in the filtration device 400 of this example has a "funnel-like" or "mortar-like" shape that gradually tapers from the circular outer periphery toward the center and is concave downward.

[0042] By making the filter bed 108A have such a shape, the filter media 110 that is kneaded and washed while being transported upward by the rotating screw blade portion 204 of the filter media washing device 200, and the contaminants that are torn off from the filter media and discharged from the treated water outlet pipe 118, tend to naturally gather near the lower end of the screw blade portion 204. This makes it possible to more efficiently knead and wash the filter media 110 and discharge the contaminants.

[0043] In this case, the area of ​​contact between the raw water before filtration and the filter material 110 through the filter bed 108A is larger than when the raw water comes into contact with the filter material 110 through the circular filter bed 108, which is also advantageous in terms of speeding up the filtration.

[0044] While the present invention has been described as including backflow cleaning (backwashing), foam cleaning of the filter material may be performed in parallel with or independently of backwashing. Foam cleaning is a process in which foam cleaning water containing a large number of fine bubbles is flowed toward the filter material 110 from below the layer of filter material 110. When this process is performed, the foam cleaning water flows between the filter materials 110, and contaminants trapped on the surface of each filter material 110 are peeled off by the vibration, impact, and contact caused by the passing bubbles. The foam cleaning water containing the peeled contaminants is discharged from the filter tank 106 through the treated water outlet pipe 118, just as in the case of backwashing.

[0045] When the foam washing described above is performed in parallel with backwashing, the cleaning effect on the filter material 110 is enhanced. Furthermore, since the amount of backwash water required can be reduced by the amount of foam washing, the amount of backwash water consumed can also be reduced. The water used to obtain the foam washing water may be a portion of the backwash water, or may be prepared separately from the backwash water. To incorporate a large number of fine bubbles into the foam washing water, a non-positive displacement pump that rotates an impeller inside a casing can be used to pump water toward the filter material 110, and the impeller can generate bubbles by cutting the water. Alternatively, if finer bubbles, such as fine bubbles or microbubbles, are desired, a dedicated foam generator that generates such bubbles can be installed in the water pumping path. [Explanation of symbols]

[0046] 100, 150, 400 filtration equipment 102 Upper end member of filtration tank 104 Bottom wall of filter tank 106 Filtration tank 108, 108A filter bed 110 Filter material 112 Strainer 114 Raw water inflow chamber 115 Raw water inlet pipe 116 Backwash water inlet pipe 118 Treated water outlet pipe 120 Filter media outlet 122 Treated Water 124 Weir plate 200, 300 Filter cleaning device 203 Rotation axis 204, 304 screw blade 206 Motor 208 Reduction mechanism section 210 Joint 212 Retaining member 214, 216 support 218 Bearings 220 Filter material flow prevention plate

Claims

1. A filter cleaning device for a filtration device that has a layer of filter material inside a filtration tank or filtration basin and filters supplied raw water by passing it through the layer of filter material, A filter material cleaning device having a spiral screw disposed upright within the layer of the filter material and a screw driving means for rotating the screw around a screw axis, wherein the filter material is kneaded and washed by rotating the screw, The screw used is a screw in which the spiral screw flight portion constituting the screw is a plurality of screw flight portions that are not continuous with each other and are arranged apart from each other in the screw axial direction, A filter medium cleaning device characterized in that the filter medium is transported upward while the outer periphery of the screw is in direct contact with the layer of the filter medium.

2. 2. The filter media cleaning device according to claim 1, wherein the plurality of screw blades are two screw blades.

3. 3. The filter media cleaning device according to claim 1, wherein the screw used is a screw having a coil spring shape in which the spiral screw blade portion constituting the screw forms a ring at a position spaced apart from the rotation axis of the screw circumferentially outward when viewed from the axial direction of the screw.

4. 3. The filter medium cleaning device according to claim 1, wherein the area of ​​the outer peripheral edge of the screw that is in direct contact with the layer of the filter medium extends over the entire length of the screw.

5. A filter material cleaning device as described in Claim 3, wherein the area in which the outer edge of the screw is in direct contact with the layer of filter material extends over the entire length of the screw.

Images