Filtration pond

Abstract

To provide a filter basin which can simplify piping and flow paths around the filter basin and is easy to construct. [Solution] A water collection device (23) consisting of multiple rows of water collection blocks (31) arranged in parallel is placed at the bottom of the tank, and filter media is placed above the water collection device (23) to filter raw water using a downward flow and clean the filter media with backflow cleaning water and air. In this filtration basin (12), the system is characterized by the following: an air distribution tank (41) arranged perpendicularly below the multiple rows of water collection blocks (31) and equipped with multiple air distribution nozzles (42) that supply air to the water collection blocks (31) of each row; an air cleaning pipe (43) that supplies air to the air distribution tank (41); a communication passage (50) that connects each water collection block (31) to the lower part of the air distribution tank (41); and a waste water valve (45) that discharges waste water from the water collection blocks (31) into a drainage culvert via the air distribution tank (41).

Description

[Technical Field]

[0001] The present invention relates to a filter basin. [Background technology]

[0002] For example, Patent Document 1 discloses a filter basin. In the filter basin, a water collection device consisting of multiple rows of water collection blocks arranged in parallel is placed at the bottom of a tank, and a filter medium is placed above the water collection device to filter raw water by a downward flow. In addition, in the filter basin, the filter medium used for filtration is washed with backwash water and air washing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-174805 Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional filters, air is supplied to each collection block through a header pipe for air distribution. This structure requires separate channels for draining wastewater from each collection block into a drainage culvert, which increases the amount of piping and complicates construction.

[0005] The present invention has been made in view of the above points, and an object of the present invention is to provide a filter basin which can simplify the piping and flow paths around the filter basin and which is easy to install. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides a filter basin in which a water collecting device consisting of multiple rows of water collecting blocks arranged in parallel is placed at the bottom of the basin, a filter medium is placed above the water collecting device to filter raw water by a downward flow, and the filter medium is washed with backwash water and air, the filter basin is characterized by comprising: an air distribution tank arranged perpendicularly below the multiple rows of water collecting blocks and equipped with multiple air distribution nozzles for supplying air to the water collecting blocks of each row; an air cleaning pipe for supplying air to the air distribution tank; a communication passage connecting each of the water collecting blocks with the lower part of the air distribution tank; and a waste water valve for discharging waste water from the water collecting blocks via the air distribution tank into a drainage culvert.

[0007] Furthermore, it is preferable that the water collection block comprises a lower outer shell body, an upper outer shell body that is formed longer in the extension direction than the lower outer shell body and is placed on top of the lower outer shell body, and a step portion formed by the lower outer shell body and the upper outer shell body, and that the air distribution tank is arranged in an installation space formed by each of the step portions of multiple rows of the water collection blocks. [Effects of the Invention]

[0008] According to the filter of the present invention, the piping and flow paths around the filter can be simplified and construction can be easily performed. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of a filtration basin facility provided with a filtration basin according to an embodiment of the present invention. [Figure 2] FIG. 2 is a plan view showing a filter basin according to the present embodiment. [Figure 3] FIG. 2 is a side view showing the water collection block according to the embodiment. [Figure 4] FIG. 2 is a cross-sectional view showing the water collecting block according to the present embodiment. [Figure 5] FIG. 2 is a perspective view showing an air distribution device for a filter basin according to the present embodiment. [Figure 6] FIG. 2 is a cross-sectional view showing the air distribution device and its surroundings of the filter basin according to the present embodiment. [Figure 7]FIG. 7 is a view taken along the line VII-VII in FIG. 6. [Figure 8] FIG. 2 is a schematic cross-sectional view showing the operation of the filter basin according to the present embodiment. [Figure 9] FIG. 2 is a schematic cross-sectional view showing the operation of the filter basin according to the present embodiment. [Figure 10] FIG. 2 is a schematic cross-sectional view showing the operation of the filter basin according to the present embodiment. [Figure 11] FIG. 2 is a schematic cross-sectional view showing the operation of the filter basin according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Next, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate. A filtration basin equipment 10 according to the embodiment of the present invention is provided in a water purification treatment system that purifies water. In addition to the filtration basin equipment 10, the water purification treatment system is configured to include a grit basin (not shown), a receiving well (also called a raw water tank in some equipment), a rapid mixing tank (mixing tank), a flocculation basin, a sedimentation basin, and a purified water basin.

[0011] As shown in FIG. 1, the filtration facility 10 includes a plurality of filtration basins 12, a raw water conduit 16, a drainage conduit 18, and a purified water conduit 19.

[0012] Each filter basin 12 is equipped with a drainage trough 21 located in the vertical middle of the filter basin 12, a filter layer 22 located below the drainage trough 21, a water collection device 23 located below the filter layer 22, and an air distribution device 24 that distributes and supplies air.

[0013] The drainage trough 21 is configured, for example, as a U-shaped drainage groove. The lower bottom wall of the drainage trough 21 is configured as an inclined surface that slopes downward from the raw water conduit 16 side toward the drainage conduit 18 side. The lower bottom wall of the drainage trough 21 may also be configured as a flat surface without being inclined.

[0014] A drain outlet 12a, which is opened and closed by a drain gate G2, is formed in the center of the height direction of the wall K2 of the body K that constitutes the filter basin 12. The end of the drain trough 21 faces the drain outlet 12a. The drain gate G2 is connected to an operating unit S3 via an operating shaft S3a. The drain gate G2 can be opened and closed by operating the operating unit S3. When the drain gate G2 is opened, the water in the filter basin 12 (water above the drain outlet 12a) can be drained into the drainage culvert 18.

[0015] The filter bed 22 is a layer of filter media such as filter sand, and is provided on the water collecting device 23. The filter media preferably has an appropriate particle size distribution, is resistant to wear, and is capable of stable and efficient filtration. The thickness of the filter bed 22 is approximately 70 to 90 cm.

[0016] The water collecting device 23 is disposed below the filter basin 12, and is a device that collects filtered water and uniformly disperses backwash water. By uniformly dispersing the backwash water, the water collecting device 23 can exert an excellent cleaning effect on the filter layer 22. As shown in Figs. 1 and 2, the water collecting device 23 is composed of a plurality of water collecting blocks 31 arranged side by side. Each water collecting block 31 is disposed on a support part 30 provided on the bottom wall (bottom) K1 of the body K. As shown in Figs. 3 and 4, the water collecting block 31 includes a lower outer shell body 32, an upper outer shell body 33, inner shell bodies 34, 34, and a perforated plate 35.

[0017] The lower shell body 32 is a groove with a U-shaped cross section, and is formed to allow filtered water to flow through it. The upper shell body 33 is connected to the top of the lower shell body 32 and has an inverted U-shaped cross section. The lower shell body 32 and the upper shell body 33 are combined to form a cylindrical body with a rectangular cross section. As shown in FIG. 3 , the lower shell body 32 is shorter in the extension direction than the upper shell body 33, and a step portion 36 is formed between the lower shell body 32 and the upper shell body 33.

[0018] 4, a support plate 33a that supports the perforated plate 35 is formed on the top of the upper shell body 33. A plurality of holes 33b are formed in the support plate 33a and penetrate the plate in the thickness direction.

[0019] As shown in Figure 4, the inner shell bodies 34, 34 are provided on the upper outer shell body 33 and are plate-like sections with an inverted V-shaped cross section. The inner shell body 34 extends in the longitudinal direction of the water collection block 31. The inner shell body 34 also has a plurality of holes 34a that penetrate through the plate thickness direction and have different hole diameters. The provision of the inner shell bodies 34, 34 increases the strength for supporting the filter layer 22. The upper inside portions of the inner shell bodies 34, 34 are sections that serve as air reservoirs for air supplied from the air cleaning pipe 43.

[0020] The perforated plate 35 is a perforated plate-like member disposed on the upper shell body 33. The perforated plate 35 is a member that allows filtered water, backwash water, and air to pass through, and also supports the filter medium of the filter layer 22.

[0021] As shown in Fig. 2, the air distribution device 24 is disposed at the lower end of the water collecting device 23 in a direction perpendicular to the water collecting blocks 31. The air distribution device 24 distributes air uniformly to each of the water collecting blocks 31. As shown in Fig. 5, the air distribution device 24 includes an air distribution tank 41, a plurality of air distribution nozzles 42, an air cleaning pipe 43, a communication passage 50 (see Fig. 6), a water discharge pipe 44, and a water discharge valve 45.

[0022] The air distribution tank 41 has side walls 46, 47 and an upper wall 48. The side walls 46, 47 are arranged parallel to each other and facing each other. The upper ends of the side walls 46, 47 are connected by the upper wall 48. As shown in FIG. 6, the air distribution tank 41 is arranged in the step portion 36 of each water collection block 31. More specifically, the air distribution tank 41 is arranged so as to be perpendicular to the water collection blocks 31 in an installation space formed by the step portions 36 of multiple rows of water collection blocks 31.

[0023] The upper wall 48 of the air distribution tank 41 abuts against the lower part of the upper outer shell body 33. The side wall 46 is arranged along the wall part K2 of the body K. The height dimension of the side wall 47 is formed shorter than that of the side wall 46. As a result, a communication passage 50 is formed between the bottom wall K1 of the body K and the lower end of the side wall 47. In other words, the communication passage 50 is a flow path that communicates between each water collection block 31 and the lower part of the air distribution tank 41.

[0024] As shown in Fig. 5, a plurality of air distribution nozzles 42 are cylindrical and installed at predetermined intervals so as to penetrate the upper wall 48. As shown in Figs. 6 and 7, a slit 42a is formed by cutting out the side of the lower end of the air distribution nozzle 42. In addition, an air hole 42b is formed in the side of the air distribution nozzle 42, penetrating in the thickness direction. The air hole 42b is located immediately below the upper wall 48. As shown in Fig. 7, the upper end of the air distribution nozzle 42 is located inside the upper outer shell 33 of the water collecting block 31, more specifically, between the inner shells 34, 34. The lower end of the air distribution nozzle 42 is located inside the air distribution tank 41.

[0025] 5 and 6, the air cleaning pipe 43 is a pipe connected perpendicularly to the side wall 46 of the air distribution device 24. One end of the air cleaning pipe 43 is connected to the side wall 46, and the other end is connected to the outside (see FIG. 1). The air cleaning pipe 43 is a member that supplies air taken in from the outside by a blower (not shown) or the like into the air distribution tank 41.

[0026] As shown in FIG. 5, the waste water pipe 44 is a pipe connected perpendicularly to the side wall 46 of the air distribution device 24. As shown in FIG. 8, the waste water pipe 44 is arranged to penetrate the lower part of the wall portion K2 of the body K. A waste water valve 45 is provided at the end of the waste water pipe 44. As shown in FIG. 1, the waste water valve 45 is connected to an operating unit S4 provided on the upper part of the body K via an operating shaft S4a extending in the vertical direction. The waste water valve 45 can be opened and closed by operating the operating unit S4. When the waste water valve 45 is opened, water in the filter basin 12 is drained into the drainage culvert 18.

[0027] As shown in FIG. 1, the raw water conduit 16 is composed of a channel through which raw water flows and supplies the raw water to the filtration basin 12. This raw water is water that has been treated in a previous process, a sedimentation basin (not shown). The raw water conduit 16 is formed with an inlet 16a and a raw water inflow gate G1 that opens and closes the inlet 16a. The raw water inflow gate G1 is connected to an operating unit S1 via an operating shaft S1a. The raw water inflow gate G1 can be opened or closed by operating the operating unit S1.

[0028] The drainage culvert 18 is provided adjacent to the filtration basin 12 and is connected to the drainage basin. The drainage culvert 18 is configured so that wastewater flows in from a drain outlet 12a and a drainage pipe 44 (a drainage valve 45).

[0029] The purified water conduit 19 is provided adjacent to the filter basin 12 and is connected to the distribution reservoir. Filtered water flows into the purified water conduit 19 from a connecting pipe 29 (purified water valve 20).

[0030] A water purification valve 20 and a connecting pipe 29 are provided at the bottom of the wall K3 of the body K. The connecting pipe 29 penetrates the wall K3 and communicates with the filter basin 12 and the water purification culvert 19. The water purification valve 20 is a valve that opens and closes the flow path of the connecting pipe 29. The water purification valve 20 is connected to an operating unit S2 provided on the body via an operating shaft S2a that extends in the vertical direction. The water purification valve 20 can be opened and closed by operating the operating unit S2. When the water purification valve 20 is opened, filtered water flows into the water purification culvert 19.

[0031] Next, a method of using the filtration basin equipment 10 according to this embodiment will be described. <Filtration method> First, the filtration method will be described. As shown in Fig. 1, the drain outlet 12a provided in the wall portion K2 of the body K is closed by the drain gate G2. In addition, the water purification valve 20 is opened, and the waste water valve 45 is closed.

[0032] Next, the raw water inlet gate G1 is opened to allow the raw water to flow into the filter basin 12. The inflowing raw water is filtered through the filter layer 22 to remove impurities. The filtered water is collected in the water collector 23 and flows into the purified water conduit 19 through the connecting pipe 29.

[0033] <How to clean the filter layer> Next, a method for cleaning the filter layer 22 (filter material) will be described. First, the raw water inlet gate G1 is closed to stop the inflow of raw water, and the purified water valve 20 is closed. Next, the drain gate G2 is opened to lower the water level in the filter basin 12. Once the water level has dropped to the position of the drain trough 21, air is supplied from below the filter layer 22 via the air cleaning pipe 43 and air distributor 24. The water level in the filter basin 12 at which air cleaning should begin is preferably near the top of the filter layer 22 (approximately 10 to 20 cm), and if the water level does not drop when the drain gate G2 is used, the wastewater valve 45 can be opened.

[0034] More specifically, as shown in Figures 8 and 9, air is supplied into the air distribution tank 41 from the air cleaning pipe 43. As shown in Figure 9, the air that flows into the air distribution tank 41 diffuses in the longitudinal direction of the air distribution tank 41. The upper part of the air distribution tank 41 becomes an air reservoir, and an air layer F1 is formed.

[0035] Furthermore, the air in the air layer F1 enters the air distribution nozzle 42 through the air holes 42b and is supplied to the top of the upper outer shell body 33 of the water collection block 31. The air supplied to the top of the upper outer shell body 33, that is, the air supplied between the inner shell bodies 34, 34 (see FIG. 7), diffuses in the longitudinal direction of the inner shell bodies 34, 34. An air pool forms between the inner shell bodies 34, 34, and an air layer F2 is formed.

[0036] As shown in Figure 10, when more air is supplied to the air distribution tank 41, the thickness of the air layer F1 increases, and air flows into the air distribution nozzle 42 through the slits 42a in addition to the air holes 42b. This increases the thickness of the air layer F2 above the upper outer shell 33. When the air layer F2 reaches the holes 34a in the inner shell 34 (see Figure 7), the air rises through the holes 34a and escapes upward through the holes 33b and the perforated plate 35 from below the filter layer 22. Air entering the filter layer 22 from below lifts impurities such as dirt. The lifted impurities and water flow down the drain trough 21 and are drained from the drain outlet 12a.

[0037] Next, the clean water valve 20 is opened, and water (backwash water) from the clean water conduit 19 is supplied from below the filter bed 22 via the water collection device 23 to perform backwashing. In other words, both air and water are supplied from below the filter bed 22 to remove impurities from the filter bed 22. Thereafter, the supply of air from the air cleaning pipe 43 is stopped, and backwashing is performed for a predetermined period of time using only the backwash water. It is preferable to stop the air cleaning when the water level in the filter bed 12 rises due to the backwash water and reaches near the bottom of the drainage trough 21.

[0038] After backwashing is complete, the clean water valve 20 is closed and the waste water valve 45 is opened to drain the water from the filter basin 12. As shown in Figure 11, the water from the filter basin 12 is drained from the waste water valve 45 to the drainage culvert 18. More specifically, the water collected in the water collection block 31 flows between the communication passages 50, passes through the air distribution tank 41, and is drained from the waste water pipe 44.

[0039] According to the filter basin 12 described above, the piping and flow paths around the filter basin 12 can be simplified, allowing for easier installation. Conventionally, air was distributed using a header pipe and nozzles, but this made the header pipe difficult to design and complicated to install. In this embodiment, air can be supplied evenly by connecting an air cleaning pipe 43 to the air distribution tank 41 without providing a header pipe and further providing multiple air distribution nozzles 42. Furthermore, the air distribution device 24 also has a drainage function, as a flow path for drainage water is formed by providing a communication passage 50 and a drainage pipe 44 (drainage valve 45) in the air distribution tank 41. This allows for simplified piping and flow paths with a reduced number of parts, allowing for easier installation.

[0040] In this embodiment, the air distribution tank 41 is disposed in the installation space defined by the step portions 36 of the multiple rows of water collection blocks 31. This allows air to be distributed evenly and also saves space.

[0041] Although the embodiment of the present invention has been described above, appropriate design changes are possible within the scope of the invention. For example, the communication passage 50 may be provided continuously or intermittently in the longitudinal direction. [Explanation of symbols]

[0042] 10 Filtration equipment 12 Filtration pond 21 Drainage trough 22 Filter layer 23 Water collection device 24 Air distribution device 31 Water collection block 41 Air distribution tank 42 Air distribution nozzle 43 Air Cleaning Pipe 44 Waste water pipe 45 Drain valve

Claims

1. In a filter basin, a water collecting device consisting of multiple rows of water collecting blocks arranged in parallel is placed at the bottom of a tank, a filter medium is placed above the water collecting device, raw water is filtered by a downward flow, and the filter medium is washed with backflow washing water and air. an air distribution tank provided below the plurality of rows of water collection blocks and perpendicular to the rows of water collection blocks, the air distribution tank including a plurality of air distribution nozzles for supplying air to the water collection blocks in each row; an air cleaning pipe supplying air to the air distribution tank; a communication passage that communicates each of the water collection blocks with a lower portion of the air distribution tank; a drainage valve for discharging the drainage water from the water collection block into a drainage culvert through the air distribution tank.

2. The water collecting block includes a lower shell body, an upper shell body formed longer in the extension direction than the lower shell body and provided on the lower shell body, and a step portion formed by the lower shell body and the upper shell body, 2. The filter according to claim 1, wherein the air distribution tank is disposed in an installation space defined by each of the stepped portions of the water collection blocks in a plurality of rows.

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