Filtration Equipment

Abstract

To provide a filter device capable of quickly returning, to a filter material layer, filter materials that have flowed out.SOLUTION: A filter device 100 includes: a filter tank 10A having a filter material layer 13A; a treated water outflow portion 14A; a cleaning wastewater discharge unit 16A; and a pressure-adjusting water tank 11A having an introducing passage 11b for introducing a treatment objective water into below the filter material layer 13A. The treatment objective water introduced into the filter tank 10A from the pressure-adjusting water tank 11A, passes through the filter material layer 13A from below to above. The filter device 100 further includes: a cleaning wastewater tank 20 that stores cleaning wastewater; and a float pump 31 and a reflux pipe 32 that suck up filter materials 13 flowing into the cleaning wastewater tank 20 together with the cleaning wastewater and return them to the pressure-adjusting water tank 11A. An outlet of the reflux pipe 32 is disposed in the introduction passage 11b. A flow passage cross-sectional area of the introduction passage 11b is designed so that a speed of a water flow passing through the introduction passage 11b is higher than floating speeds of the filter materials 13.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a filtration device capable of filtering water to be treated. [Background technology]

[0002] Conventionally, there is known a filtration device that forms a filter layer using a filter medium that floats in water and filters the water to be treated. In such a filtration device, dirt adheres to the filter medium during the filtration process, so the filter medium is periodically backwashed to clean it. However, if the filter medium flows out together with the washing wastewater during the backwash and the thickness of the filter medium layer decreases, the filtration performance decreases. Therefore, a process is performed in which the filter medium that flows out during the backwash is returned to the filtration tank.

[0003] For example, Patent Document 1 discloses a moving bed filtration device in which a filter media layer is formed in a filtration tank, raw water is passed from top to bottom through the filter media layer to be filtered, and part of the filter media is withdrawn from the filtration tank together with the raw water through a filter media withdrawal pipe to be purified, and then the filter media is returned to the filtration tank. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2005-7301 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the moving bed filtration apparatus of Patent Document 1, the filter medium is returned from below the filtration tank through an opening in the guide wall, so that only small amounts can be returned at a time, and the return process takes a certain amount of time, which is a problem.

[0006] The present invention has been made in consideration of the above problems, and has an object to provide a filtration device that can quickly return the flowing-out filter medium to the filter medium layer. [Means for solving the problem]

[0007] In order to achieve the above object, the filtration device of the present invention comprises a filtration tank in which a filter layer is formed by accumulating a predetermined thickness of a plurality of filter media, each of which is buoyant in the water to be treated, with its upward movement restricted by a screen but its downward movement not restricted, an outlet portion for water treated by filtration provided above the filter layer in the filtration tank, a discharge portion for washing wastewater provided below the filter layer in the filtration tank, and a pressure adjusting tank having an inlet path for introducing the water to be treated below the filter layer in the filtration tank, In a filtration device configured such that the water to be treated introduced from the pressure adjusting tank to the filtration tank passes through the filter layer from the bottom to the top due to a water level difference between the water level of the water to be treated introduced into the pressure adjusting tank and the water level of the filtration tank, The system comprises a cleaning drain tank for storing the cleaning drainage water flowing out from the discharge section, and a pump and return piping for sucking up the filter material that has flowed into the cleaning drain tank together with the cleaning drainage water and returning it to the pressure-regulating water tank, wherein the outlet of the return piping is arranged within the inlet passage of the pressure-regulating water tank, and the flow path cross-sectional area of ​​the inlet passage is set so that the speed of the water flow passing through the inlet passage is faster than the floating speed of the filter material.

[0008] In the filtration tank of the present invention, a plurality of filter media, which are buoyant in the water to be treated, are restricted in their upward movement by a screen, but are not restricted in their downward movement, and are piled up to a predetermined thickness to form a filter media layer, which can eliminate clogging of the screen below that occurs when a screen is provided below. Meanwhile, since there is no screen below the filter media layer, the filter media may flow out into the cleaning wastewater tank together with the cleaning wastewater during backwashing, but it can be returned to the pressure adjusting tank by a pump and return piping.

[0009] The outlet of the return pipe is placed in the inlet of the pressure adjusting tank, and the cross-sectional area of ​​the inlet is set so that the speed of the water flow passing through the inlet is faster than the floating speed of the filter media. Therefore, the filter media is pushed out of the outlet by the water flow that overcomes the floating speed, and the filter media can be quickly returned to the filter media layer (below).

[0010] In the filtration device of the present invention, it is preferable to have a filter medium detection means for detecting filter medium floating on the water surface of the cleaning drainage tank, and a control means for operating the pump to circulate the filter medium when the filter medium detection means detects a predetermined amount or more of filter medium.

[0011] When the filter media detection means detects that a predetermined amount or more of filter media is floating on the water surface of the cleaning drainage tank, the control means operates the pump to return the filter media. This allows the filter media that has flowed out during the backwash process to be appropriately returned.

[0012] In addition, in the filtration device of the present invention, a plurality of sets of the filtration tank and the pressure adjusting tank are provided, and the discharge portion of each filtration tank is connected to a common cleaning drain tank, The control means The filter media flowing out from the filter media layer of each of the filtration tanks amount A leaked information acquisition means for acquiring leaked information related to the above, and based on the leaked information acquired by the leaked information acquisition means, To prevent unevenness in the thickness of the filter media layers in each of the filtration tanks, It is preferable that the washing system further comprises an adjusting means for adjusting the amount of the filter medium that has flowed into the washing wastewater and is returned to each of the filtration tanks.

[0013] The outflow information acquisition means acquires outflow information (e.g., outflow amount) related to the filter media that has flowed out from the filter media layer of each filter tank. The adjustment means adjusts the return amount of the filter media that has flowed into the cleaning wastewater to each filter tank based on the outflow information, so that the amount of filter media in each filter tank can be kept uniform.

[0014] In addition, in the filtration device of the present invention, The thickness of the filter medium layer of each of the filtration tanks is By light Inspection The outflow information acquisition means is provided with a light detection means for emitting light detected by the light detection means. The thickness of each filter layer is used to determine the filter medium of each filter tank. It is preferable to obtain leaked information.

[0015] The position of the filter media in each filter layer is detected by the light detection means, and the detected value reflects the thickness of the filter media layer. Therefore, when the outflow information acquisition means receives the outflow information, the amount of filter media returned is controlled to be greater in a filter tank with a thinner filter media layer. This makes it possible to keep the amount of filter media in each filter tank equal.

[0016] In addition, in the filtration device of the present invention, a water level difference detection means is provided for detecting a water level difference between the water level of the water to be treated introduced into the pressure adjusting tank and the water level of the filtration tank when the filtration process is resumed after the backwash process and the inflow rate of the water to be treated is made constant, The outflow information acquisition means is The filtration loss resistance of each filtration tank is calculated based on the water level difference, and the thickness of the filter layer of each filtration tank is calculated based on the filtration loss resistance. It is preferable to obtain leaked information.

[0017] When the filtration process is resumed after the backwash process and the inflow rate of the water to be treated is made constant, the water level difference between the water level of the water to be treated introduced into the pressure adjusting tank and the water level of the filtration tank is detected by the water level difference detection means, and this water level difference reflects the filtration loss resistance (water flow resistance) of the washed filter layer. Since the filtration loss resistance increases according to the thickness of the filter layer, the larger the water level difference, the thicker the filter layer.

[0018] Therefore, when the outflow information acquisition means receives the outflow information, it is estimated that the smaller the water level difference is, the thinner the filter layer is, and the smaller the water level difference is, the larger the return amount of the filter material is controlled. This makes it possible to keep the amount of filter material in each filter material tank uniform.

[0019] In the filtration device of the present invention, the pump is preferably a float pump.

[0020] By using a float pump, the filter media floating on the water surface of the cleaning drainage tank can be efficiently sucked up and returned. [Brief description of the drawings]

[0021] [Figure 1] 1 is an overall configuration diagram showing a first embodiment of a filtration device of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view showing one of the filtration tanks in FIG. 1. [Diagram 3] FIG. 2 is a block diagram showing functional blocks of the filtering device according to the first embodiment. [Figure 4] 4 is a flowchart showing the overall process of the filtration device. [Diagram 5] 5 is a flowchart showing a subroutine of the reflux process in FIG. 4. [Figure 6] FIG. 11 is a cross-sectional view showing a filtration device (one of the filtration tanks) of a second embodiment. [Figure 7] FIG. 6 is a block diagram showing functional blocks of a filtering device according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, an embodiment of a filtering device according to the present invention will be described with reference to the drawings.

[0023] [First embodiment] Fig. 1 is an overall configuration diagram showing a first embodiment of a filtration device of the present invention, and Fig. 2 shows a cross-sectional view of one of the filtration tanks of Fig. 1.

[0024] 1, the filtration device 100 has three filtration tanks 10A, 10B, and 10C, a cleaning drainage tank 20 capable of storing the cleaning wastewater and filter media 13 discharged from each of the filtration tanks 10A, 10B, and 10C, and a return means 30 for returning the filter media 13 in the cleaning drainage tank 20 together with the cleaning wastewater to the pressure adjustment tanks 11A, 11B, and 11C provided in each of the filtration tanks 10A, 10B, and 10C. Note that, although the present embodiment describes a case in which there are three filtration tanks, there may be one or two or more filtration tanks, and the number is not limited.

[0025] Each of the filtration tanks 10A, 10B, and 10C includes a pressure-adjusting water tank 11A, 11B, and 11C into which the water to be treated flows, a filter layer 13A, 13B, and 13C in which a plurality of filter media 13 that are buoyant in the water to be treated are restricted in their upward movement by screens 12A, 12B, and 12C and accumulated to a predetermined thickness, and a filter layer 13A, 13B, and 13C in which the water to be treated flowing in from the pressure-adjusting water tank 11A, 11B, and 11C is filtered by the filter layer 13A, 13B, and 13C. The system has ascending flow paths 15A, 15B, 15C for passing water from below to above, treated water outlet portions 14A, 14B, 14C for extracting treated water that has passed through filter media layers 13A, 13B, 13C, aeration means 18A, 18B, 18C arranged below filter media layers 13A, 13B, 13C, and washing wastewater discharge portions 16A, 16B, 16C arranged below filter media layers 13A, 13B, 13C.

[0026] Each of the filtration tanks 10A, 10B, and 10C is formed in a tank shape with a bottom. Each of the filtration tanks 10A, 10B, and 10C is provided with a partition wall that is formed from top to bottom and divides the inside into two. Each of the filtration tanks 10A, 10B, and 10C is formed so that the insides divided by the partition wall at the bottom are connected to each other.

[0027] One side divided by the partition wall is pressure-adjusting water tanks 11A, 11B, and 11C. As shown in Fig. 2, pressure-adjusting water tank 11A (11B, 11C) is formed so as to obtain a flow rate of the water to be treated that can move filter medium 13 to the bottom side against the buoyancy of filter medium 13.

[0028] In this embodiment, the pressure adjusting tank 11A is formed in a cone shape so that the opening diameter narrows toward the bottom. Specifically, the pressure adjusting tank 11A is composed of a cone-shaped water receiving portion 11a (flow speed: 1 to 2 m / min) and a cylindrical introduction passage 11b (flow speed: approximately 20 m / min) connected to the lower part of the water receiving portion 11a.

[0029] The cross-sectional area of ​​the introduction passage 11b is set so that the speed of the water flow passing through is faster than the floating speed of the filter medium 13 (1 / 10 to 1 / 20 of the bottom area of ​​the filtration tank 10A), and the water to be treated is introduced into the filtration tank 10A at a position lower than the filter medium layer 13A (13B, 13C) of the filtration tank 10A (10B, 10C). That is, the treated water flows out of the treated water outlet 14A (14B, 14C) at the same flow rate as the water to be treated flowing in from the inlet 19A (19B, 19C), so the smaller the cross-sectional area of ​​the introduction passage 11b, the faster the flow rate of the downward flow becomes. And, because the flow rate of the downward flow becomes faster than the floating speed of the filter medium 13, the filter medium 13 flows down the introduction passage 11b.

[0030] Returning to Fig. 1, the pressure adjusting water tanks 11A, 11B, and 11C are provided with inflow sections 19A, 19B, and 19C into which the water to be treated flows in, respectively. In addition, the pressure adjusting water tanks 11A, 11B, and 11C are provided with reflux piping 32 of reflux means 30 so as to be able to merge with the water to be treated flowing in from the inflow sections 19A, 19B, and 19C.

[0031] In particular, the outlet (tip) of the return pipe 32 is disposed in the introduction passage 11b of the pressure-adjusting water tanks 11A, 11B, and 11C, respectively. This is because if the outlet of the return pipe 32 is disposed in the water receiving section 11a and the filter medium 13 is returned, the filter medium 13 will not reach the filtration tanks 10A, 10B, and 10C due to the buoyancy of the filter medium 13. As a result, the filter medium 13 is pushed out by the water current that overcomes the floating speed, and the filter medium 13 can be quickly returned to the bottom of the filtration tanks 10A, 10B, and 10C.

[0032] On the other side divided by the partition, treated water outflow portions 14A, 14B, and 14C are provided at the top. Screens 12A, 12B, and 12C are disposed between treated water outflow portions 14A, 14B, and 14C and the bottom.

[0033] There are no particular limitations on the screens 12A, 12B, and 12C as long as they are capable of restricting the upward movement of the filter medium 13. For example, punched metal having a large number of holes smaller than the filter medium 13 may be used.

[0034] The filter medium 13 is buoyant in the water to be treated and has a shape capable of capturing solid matter contained in the water to be treated as the water passes through. The filter medium 13 is preferably formed in a cylindrical or plate shape and has a large surface area by forming a plurality of protrusions, protruding pieces, etc. on the outer periphery. For example, the filter medium 13 may be formed in a windmill shape having blade-like protruding pieces protruding in four directions perpendicular to each other from the central axis toward the outer periphery. The filter medium 13 is not limited to such a shape, and may be, for example, a cylindrical filter medium.

[0035] The size of the filter medium 13 can be appropriately selected depending on the material to be filtered. For example, when the material is SS (Suspended Solid), the maximum diameter is preferably about 5 to 50 mm. For example, the windmill type is preferably 7.5 mm (length) x 7.5 mm (width) x 4 mm (thickness). The filter medium 13 may be made of any material that has buoyancy in the water to be treated, such as foamed resin. The specific gravity of the filter medium 13 may be lower than 1.0, but is preferably 0.1 or more and less than 0.8.

[0036] Therefore, upward movement of the filter media 13 is restricted by the screens 12A, 12B, and 12C. The filter media 13 are accumulated below the screens 12A, 12B, and 12C to form filter media layers 13A, 13B, and 13C.

[0037] The thickness of the filter layers 13A, 13B, and 13C is not particularly limited, but is preferably about 20 to 120 cm, and most preferably 70 cm. The porosity of the filter layers 13A, 13B, and 13C (the ratio of the volume of the voids formed by the gaps in the filter 13 to the volume of the entire filter layer) is preferably about 20 to 80%, and most preferably about 50%. The porosity can be measured by a water displacement method.

[0038] The treated water outflow sections 14A, 14B, and 14C are provided at a predetermined distance above the positions where the screens 12A, 12B, and 12C are provided. The predetermined distance from the height of the screens 12A, 12B, and 12C to the treated water outflow sections 14A, 14B, and 14 is set so as to provide a water pressure necessary to wash away dirt from the filter media 13 of the filter media layers 13A, 13B, and 13C toward the bottom during backwashing. The predetermined distance is preferably about 0.5 to 1.5 m, and most preferably about 1 m.

[0039] The inflow sections 19A, 19B, and 19C are provided at a higher position than the treated water outflow sections 14A, 14B, and 14C. The height difference between the two is set so that the water to be treated that flows into the pressure-adjusting water tanks 11A, 11B, and 11C can rise through the ascending flow paths 15A, 15B, and 15C and pass through the filter layers 13A, 13B, and 13C. In other words, the treated water that passes through the filter layers 13A, 13B, and 13C of the filtration tanks 10A, 10B, and 10C flows out from the treated water outflow sections 14A, 14B, and 14C, so that the water level of the filtration tanks 10A, 10B, and 10C is at the height of the treated water outflow sections 14A, 14B, and 14C.

[0040] In contrast, the inlet sections 19A, 19B, 19C are located at a higher position than the treated water outlet sections 14A, 14B, 14, so that the water level in the pressure regulating tanks 11A, 11B, 11C is higher than the water level in the filtration tanks 10A, 10B, 10C, and the difference in water level creates water pressure that rises up the ascending flow paths 15A, 15B, 15C.

[0041] And, since the treated water flows out of the treated water outlets 14A, 14B, 14C at the same flow rate as the water to be treated flowing in from the inlets 19A, 19B, 19C, the higher the filtration loss resistance of the filter layers 13A, 13B, 13C, the larger the water level difference becomes, and the water level of the pressure adjusting water tanks 11A, 11B, 11C rises. Therefore, the height of the inlets 19A, 19B, 19C must be at a height that allows the water level of the pressure adjusting water tanks 11A, 11B, 11C to rise, and is therefore set at a position preferably about 50 to 300 cm higher than the treated water outlets 14A, 14B, 14C.

[0042] The water level difference creates a water current, and the water to be treated flows in from inlets 19A, 19B, 19C, passes through pressure-adjusting tanks 11A, 11B, 11C, and moves upward from the bottom of filtration tanks 10A, 10B, 10C. In other words, the upward flow paths 15A, 15B, 15C run from the bottom of filtration tanks 10A, 10B, 10C to treated water outlets 14A, 14B, 14C.

[0043] Therefore, the water to be treated flowing in from the inflow portions 19A, 19B, and 19C is finally filtered by the filter layers 13A, 13B, and 13C to become treated water. Then, the treated water is discharged to the outside from the treated water outflow portions 14A, 14B, and 14C.

[0044] The washing wastewater discharge parts 16A, 16B, 16C are provided near the bottoms of the filtration tanks 10A, 10B, 10C. The washing wastewater discharge parts 16A, 16B, 16C are provided with washing drain valves 17A, 17B, 17C, respectively.

[0045] The cleaning drain valves 17A, 17B, and 17C each control the discharge of cleaning drain from the filtration tanks 10A, 10B, and 10C during backwashing. Each of the cleaning drain valves 17A, 17B, and 17C can be opened and closed in response to a signal from a control unit (not shown). Each of the cleaning drain discharge parts 16A, 16B, and 16C is connected to a cleaning drain tank 20 by a pipe 17.

[0046] Each of the aeration means 18A, 18B, 18C includes a pipe having an outlet hole (not shown) at the tip thereof through which air can be ejected, an on-off valve (not shown), and a compressor (not shown). When the filtration loss resistance (also called filtration head loss, which corresponds to the difference in water level between the water surface of the pressure adjustment water tank 11A, 11B, 11C and the water surface of the filtration tank 10A, 10B, 10C) of the filter medium layers 13A, 13B, 13C reaches a predetermined value, each of the aeration means 18A, 18B, 18C opens the on-off valve to aerate and stir the filter medium 13, thereby separating and dropping the captured SS (Suspended Solids) attached to the filter medium 13.

[0047] In addition, when backwashing the filtration tanks 10A, 10B, and 10C, the aeration means 18A, 18B, and 18C perform pulse aeration by intermittently opening and closing the on-off valve and intermittently ejecting compressed air supplied from the compressor from the ejection holes. This agitates and disperses the filter medium 13 located below the filter medium layers 13A, 13B, and 13C, making it easier to peel off the SS (Suspended Solid) attached to the surface of the filter medium 13. In addition, the filter medium 13 is dispersed and leveled, making it less likely to flow out of the cleaning wastewater discharge parts 16A, 16B, and 16C.

[0048] The cleaning drain tank 20 is formed in a tank shape so that it can store the cleaning drain and the filter media 13 flowing out from each of the cleaning drain discharge parts 16A, 16B, 16C during backwashing of the three filtration tanks 10A, 10B, 10C. The cleaning drain tank 20 is also provided with a camera 60 capable of capturing an image of the filter media 13 flowing out from each of the filtration tanks 10A, 10B, 10C.

[0049] Furthermore, the washing drainage tank 20 is provided with an outlet 21 on the bottom side through which the washing drainage can be discharged to the outside. With this configuration, solid matter that has settled and accumulated at the bottom of the washing drainage tank 20 can be discharged to the outside together with the washing drainage.

[0050] Therefore, when the cleaning drain valves 17A, 17B, and 17C are opened, the water in the ascending flow paths 15A, 15B, and 15C flows down to backwash the filter layers 13A, 13B, and 13C. The cleaning drain that passes from above to below the filter layers 13A, 13B, and 13C flows out of the cleaning drain discharge parts 16A, 16B, and 16C together with the filter media 13, and is stored in the cleaning drain tank 20 through the pipe 17.

[0051] The return means 30 can return the filter medium 13 flowing out from the cleaning wastewater discharge portions 16A, 16B, 16C to each of the three pressure adjustment tanks 11A, 11B, 11C together with the cleaning wastewater.

[0052] The reflux means 30 is composed of a float pump 31 provided in the cleaning drainage tank 20, a reflux piping 32 connecting the float pump 31 to the pressure regulating tanks 11A, 11B, and 11C, and a valve 33 capable of switching the connection direction of the reflux piping 32 to any one of the pressure regulating tanks 11A, 11B, and 11C.

[0053] The float pump 31 is provided so as to be able to float on the cleaning wastewater stored in the cleaning wastewater tank 20. The float pump 31 is capable of sucking in the cleaning wastewater and the filter media 13 in the cleaning wastewater tank 20, and sends out the sucked in cleaning wastewater and the filter media 13 to the return pipe 32.

[0054] The float pump 31 is started upon receiving a signal from a control unit, which will be described later. A camera 60 capable of capturing an image of the water surface of the cleaning drain tank 20 is installed as a filter medium detection means, so that the captured image data can be analyzed by another device, and when it is determined that a predetermined amount of filter medium 13 has accumulated, the float pump 31 can be started. Another sensor may be used as the filter medium detection means, or the float pump 31 may be started at an appropriate time of day (for example, 5 p.m.).

[0055] It is difficult to recover the lumps of filter media 13 that have settled to the bottom of the cleaning drainage tank 20. In other words, only the filter media 13 floating on the water surface of the cleaning drainage tank 20 is recovered, and the water surface of the cleaning drainage tank 20 is kept clean by the reflux process.

[0056] The valve 33 as a distribution control means can switch the connection destination of the return pipe 32 to any one of the filtration tanks 10A, 10B, 10C (pressure adjustment tanks 11A, 11B, 11C) upon receiving a signal from a control unit described later. The valve 33 can also switch the connection destination of the return pipe 32 based on the lapse of a predetermined period of time.

[0057] The valve 33 need only be capable of adjusting the flow rate of the cleaning wastewater flowing into each of the filtration tanks 10A, 10B, and 10C, and may, for example, have a plurality of valves that can independently adjust the degree of opening and closing of the flow paths leading to each of the filtration tanks 10A, 10B, and 10C.

[0058] 2, the filtration tank 10A (10B, 10C) has a detection means 40 capable of detecting the thickness of the filter layer 13A (13B, 13C). The detection means 40 is not particularly limited, but in this embodiment, it is composed of light-emitting elements 41A, 41B capable of emitting emitted light, and light-receiving elements 42A, 42B capable of receiving the emitted light L emitted from the light-emitting elements 41A, 41B.

[0059] The detection means 40 is not limited to an optical sensor, and may be, for example, a sensor using ultrasonic waves. The filtration tank 10A may be partially glassed so that the thickness of the filter layer 13A can be visually ascertained. By coloring the filter layers 13A, 13B, and 13C of the filter medium 13 in different colors, it is possible to easily confirm which filter tank the filter medium 13 has flowed out from. Information on the thicknesses and outflow amounts of the filter layers 13A, 13B, and 13C (outflow information) is also used in the reflux process in which the filter medium 13 is refluxed.

[0060] The light emitting elements 41A and 41B can be configured using, for example, light emitting diodes, laser diodes, etc. The light emitting elements 41A and 41B are provided at different positions in the vertical direction on the inner wall of the filtration tank 10A. The light emitting elements 41A and 41B are provided below the screens 12A (12B and 12C).

[0061] The light receiving elements 42A and 42B may be formed using, for example, photodiodes. The light receiving elements 42A and 42B are provided at different positions in the vertical direction on the inner wall of the filtration tank 10A and are provided opposite the light emitting elements 41A and 41B.

[0062] The light emitting elements 41A and 41B and the light receiving elements 42A and 42B are provided according to their vertical positions. In other words, the light receiving elements 42A and 42B are capable of receiving the emitted light L according to the thickness of the filter layer 13A.

[0063] 2, the light receiving element 42B receives the emitted light L emitted from the light emitting element 41B. The light receiving element 42A cannot receive the emitted light L because the emitted light L from the light emitting element 41A is blocked by the filter medium 13. Therefore, in this example, it can be seen that the thickness of the filter medium layer 13A is thinner than the position where the light receiving element 42B is provided and thicker than the position where the light receiving element 42A is provided.

[0064] For convenience, only two sets of light-emitting elements 41A, 41B and light-receiving elements 42A, 42B are shown, but in reality, multiple sets are installed at a predetermined interval in the vertical direction, and the distance of the filter material 13 located at the bottom from the screen 12A, i.e., the thickness of the filter material 13, can be determined depending on which set of light-receiving elements is able to receive the transmitted light.

[0065] 3 shows functional blocks of the control unit 50 of the filtration device 100. As shown in the figure, the input section 51 of the control unit 50 is an interface section connected to the camera 60, the detection means 40, and the cleaning and drainage valves 17A, 17B, and 17C.

[0066] The storage unit 52 is configured with a storage device such as a flash memory. The storage unit 52 stores various programs such as a BIOS (Basic Input Output System) and software. The storage unit 52 can also store the imaging data transmitted from the camera 60 and the detection data transmitted from the detection means 40, that is, outflow information related to the outflowed filter medium 13. The outflow information includes data linking the outflow information transmitted from the detection means 40 with the time at which the outflow information was received. For example, the outflow information records the time at which the light receiving elements 42A and 42B received the emitted light L.

[0067] The output unit 53 is an interface unit connected to the cleaning and draining valves 17A, 17B, and 17C, the valve 33, and the aeration means 18A, 18B, and 18C. The filtration device 100 can control the operation of the cleaning and draining valves 17A, 17B, and 17C, the valve 33, and the aeration means 18A, 18B, and 18C via the output unit 53.

[0068] The control unit 54 is realized by a computer having a CPU (Central Processing Unit) as an arithmetic processing device, a ROM (Read Only Memory) as a main storage device, and a RAM (Random Access Memory). The CPU reads out a program corresponding to the processing contents from the ROM or the storage unit 52, loads it into the RAM, and cooperates with the loaded program to realize various functions.

[0069] The input section 51 , the storage section 52 , the output section 53 and the control section 54 of the control unit 50 are connected to each other via a system bus 55 .

[0070] The outflow information acquisition means 54a is one of the functional blocks of the control unit 54. The outflow information acquisition means 54a can acquire outflow information stored in the memory unit 52. Therefore, the control unit 54 acquires outflow information related to the filter media 13 that has flowed out from the cleaning wastewater discharge units 16A, 16B, and 16C of the filtration tanks 10A, 10B, and 10C, respectively.

[0071] The adjustment means 54b is also one of the functional blocks of the control unit 54, and can adjust the operation of the valve 33 based on the outflow information. Therefore, the control unit 54 adjusts the amount of filter media 13 to be returned from the return means 30 to each of the filtration tanks 10A, 10B, 10C (pressure-adjusting tanks 11A, 11B, 11C) based on the outflow information. The adjustment means 54b can, for example, switch each connection destination or adjust the degree of opening and closing (flow rate) of each connection destination.

[0072] The operation control section 54c is also one of the functional blocks of the control section 54, and can control the cleaning and drainage valves 17A, 17B, and 17C and the aeration means 18A, 18B, and 18C.

[0073] Next, a description will be given of the overall process of the above-mentioned filtration device 100. Fig. 4 is a flowchart showing the overall process of the filtration device 100. The overall process is executed when the value of the filtration loss resistance of the filter media layers 13A, 13B, and 13C reaches a predetermined value.

[0074] As mentioned above, the filtration loss resistance of the filter media layers 13A, 13B, 13C corresponds to the water level difference between the water surface of the pressure regulating tanks 11A, 11B, 11C and the water surface of the filtration tanks 10A, 10B, 10C. Therefore, when this water level difference reaches a predetermined value, the main process including backwashing can be started.

[0075] When this process is started, first, the operation control section 54c (see FIG. 3) of the filtration device 100 transmits a signal to start the opening operation of the cleaning drain valves 17A, 17B, 17C, and transmits a signal to start the aeration means 18A, 18B, 18C to perform backwashing (step S101). In other words, backwashing is performed by passing the treated water from above to below the filter media layers 13A, 13B, 13C while performing pulse aeration from below the filter media layers 13A, 13B, 13C of the filtration tanks 10A, 10B, 10C at predetermined time intervals.

[0076] Next, the operation control unit 54c of the filtration device 100 stores the cleaning wastewater in the cleaning wastewater tank 20 (step S102). In other words, the operation control unit 54c discharges the cleaning wastewater that has passed through the filter media layers 13A, 13B, and 13C to the outside and stores it in the cleaning wastewater tank 20. The operation control unit 54c transmits a signal to start the closing operation of the cleaning wastewater valves 17A, 17B, and 17C after a predetermined time has elapsed.

[0077] Next, the operation control unit 54c of the filtration device 100 judges whether or not the backwash has been completed based on the opening and closing operations of the cleaning drain valves 17A, 17B, and 17C (step S103). This judgment is made, for example, based on receiving a signal from the cleaning drain valves 17A, 17B, and 17C indicating that the closing operation has been completed. This judgment may be made, for example, based on the elapsed time after the signal to open the cleaning drain valves 17A, 17B, and 17C was sent, the position of the water surface on the side where the screens 12A, 12B, and 12C of the filtration tanks 10A, 10B, and 10C are arranged, etc.

[0078] When it is determined in step S103 that the backwashing has not been completed (step S103: NO), the operation control unit 54c waits until the backwashing is completed.

[0079] On the other hand, when the operation control unit 54c determines in step S103 that the backwashing is completed (step S103: YES), it determines whether or not the return of the filter medium is necessary (step S104). This determination is made based on, for example, whether or not a predetermined amount or more of the filter medium 13 is confirmed in the cleaning drain tank 20 in the image data captured by the camera 60.

[0080] When it is determined in step S104 that the return of the filter medium is not necessary, that is, when the confirmed amount of the filter medium 13 is less than the predetermined amount (step S104: NO), the operation control unit 54c ends the entire process.

[0081] On the other hand, when the operation control unit 54c determines in step S104 that the filter medium needs to be returned, that is, when the confirmed filter medium 13 is equal to or greater than a predetermined amount (step S104: YES), the operation control unit 54c performs a return process (step S105). The details of the return process will be described later. After that, the entire process ends.

[0082] Fig. 5 shows a subroutine of the reflux process in step S105 in Fig. 4. As shown in Fig. 5, the outflow information acquisition means 54a reads outflow information related to the filter medium from the storage unit 52 and acquires the outflow information (step S201).

[0083] The adjusting means 54b judges whether or not there is a bias in the thickness of each filter layer based on the outflow information acquired in step S201 (step S202). This judgment is performed, for example, by checking whether or not the absolute value of the difference in thickness between the filter layers 13A, 13B, and 13C is equal to or greater than a predetermined value.

[0084] When it is determined in step S202 that there is a deviation in the thickness of each of the filter media layers 13A, 13B, 13C (step S202: YES), the adjusting means 54b ranks the filter media layers in order of thickness (step S203).

[0085] Next, the adjustment means 54b returns the filter media 13 together with the cleaning wastewater to the filtration tanks 10A, 10B, 10C (pressure-regulating tanks 11A, 11B, 11C) according to the ranking performed in step S203 (step S204). Specifically, the adjustment means 54b can adjust the return amount of the filter media 13 by controlling the open time of the valve 33 for returning the water to each of the filtration tanks 10A, 10B, 10C according to the thickness (ranking order) of the filter media layers 13A, 13B, 13C.

[0086] On the other hand, when it is determined in step S202 that there is no bias in the thickness of each of the filter media layers 13A, 13B, and 13C (step S202: NO), the adjusting means 54b performs uniform reflux for each of the filtration tanks 10A, 10B, and 10C (step S205). That is, the adjusting means 54b controls the valves 33 to be open for the same time for each of the pressure adjustment tanks 11A, 11B, and 11C.

[0087] As described above, according to the filtration device 100 of the first embodiment, the amount of filter media 13 returned to each of the multiple filtration tanks 10A, 10B, 10C can be adjusted based on the outflow information, so that it is possible to prevent unevenness in the thicknesses of the filter media layers 13A, 13B, 13C in the multiple filtration tanks 10A, 10B, 10C. In other words, the filtration device 100 can prevent unevenness in the filtration performance in the filtration tanks 10A, 10B, 10C.

[0088] [Second embodiment] In the above-described first embodiment, an example has been described in which the thicknesses of the filter layers 13A, 13B, and 13C are detected by the detection means 40. The thicknesses of the filter layers 13A, 13B, and 13C may be calculated based on the filtration loss resistances of the filtration tanks 10A, 10B, and 10C. In the following, the same components as those in the first embodiment are denoted by the same reference numerals and will not be described.

[0089] 6 shows a filtration tank 10A (10B, 10C) of a filtration device 200 according to the second embodiment. Each of the filtration tanks 10A, 10B, 10C is provided with a water level sensor 70 (water level difference detection means) that measures the water level of the pressure adjustment tanks 11A, 11B, 11C in order to detect the filtration loss resistance.

[0090] When the flow rate of the water to be treated flowing into the pressure regulating tanks 11A, 11B, and 11C is the same, the water level difference between the water level measured by this water level sensor 70 and the height of the treated water outflow sections 14A, 14B, and 14C is a value representing the filtration loss resistance of each filtration tank 10A, 10B, and 10C at the above-mentioned flow rate of the treated water.

[0091] 7 shows functional blocks of a control unit 50' of a filtration device 200 according to embodiment 4. As shown in the figure, a water level sensor 70 measures the water levels of the pressure adjustment tanks 11A, 11B, and 11C of the filtration tanks 10A, 10B, and 10C when the flow rates of treated water flowing into the pressure adjustment tanks 11A, 11B, and 11C are the same, and outputs the measured values ​​to the control unit 50'. The measured values ​​are stored in a memory unit 52.

[0092] The calculation means 54d of the control unit 54' calculates the filtration loss resistance of each filtration tank 10A, 10B, 10C at the flow rate of the treated water based on the water level difference between the water level measured by the water level sensor 70 and the height of the treated water outflow portions 14A, 14B, 14C.

[0093] The calculation means 54d can calculate the thickness of the filter media layers 13A, 13B, 13C based on the filtration loss resistance of each of the filtration tanks 10A, 10B, 10C measured immediately after the backwash is completed. In other words, assuming that the adhesion amount of SS (Suspended Solids) and the like is the same after the backwash, the filtration loss resistance is proportional to the thickness of the filter media layers 13A, 13B, 13C, and the larger the filtration loss resistance, the thicker the filter media layers 13A, 13B, 13C.

[0094] Therefore, by determining in advance the relationship between the filtration loss resistance and the thickness of the filter media layers 13A, 13B, and 13C, the calculation means 54d can calculate the thickness of each of the filter media layers 13A, 13B, and 13C.

[0095] In this way, in the filtration device 200 of the second embodiment, it is possible to prevent unevenness in the thicknesses of the filter media layers 13A, 13B, and 13C of the filtration tanks 10A, 10B, and 10C. This makes it possible to prevent unevenness in the filtration performance of the multiple filtration tanks 10A, 10B, and 10C.

[0096] Furthermore, according to the above method, the thicknesses of the filter media layers 13A, 13B, and 13C of the filter tanks 10A, 10B, and 10C can be kept uniform, so that the filtering capabilities of the filter tanks 10A, 10B, and 10C can be kept uniform. Note that the flow charts shown in Figures 4 and 5 are one embodiment of the processing performed in the filtration device 100, and the procedure of the filter media return processing in the present invention is not limited to the procedure shown in the flow charts. [Explanation of symbols]

[0097] 10A, 10B, 10C Filtration tank 11A, 11B, 11C Pressure adjusting tank 11a Water receiving part 11b Introductory path 12A, 12B, 12C Screen 13 Filter media 13A, 13B, 13C Filter layer 14A, 14B, 14C Treated water outflow section 15A, 15B, 15C Upward flow path 16A, 16B, 16C Washing drainage discharge section 17A, 17B, 17C Cleaning drain valve 18A,18B,18C Aeration means 19A,19B,19C Inlet 20 Washing drainage tank 31 Float Pump 32 Return piping 33 Valve 40 Detection Methods 41A, 41B Light emitting element 42A, 42B Light receiving element 50,50' control unit 60 Cameras 70 Water level sensor 100,200 Filtration equipment

Claims

1. a filtration tank in which a plurality of filter media, each of which is buoyant in the water to be treated, are stacked to a predetermined thickness to form a filter layer, the upward movement of which is restricted by a screen, while the downward movement of which is not restricted; An outlet for filtered water is provided above the filter layer of the filtration tank; A drainage section for cleaning wastewater provided below the filter layer of the filtration tank; A pressure adjusting tank having an inlet passage for introducing the water to be treated below the filter layer of the filtration tank, In a filtration device configured such that the water to be treated introduced from the pressure adjusting tank to the filtration tank passes through the filter layer from the bottom to the top due to a water level difference between the water level of the water to be treated introduced into the pressure adjusting tank and the water level of the filtration tank, A cleaning wastewater tank for storing cleaning wastewater flowing out from the discharge portion; A pump and a return pipe for sucking up the filter material flowing into the cleaning wastewater tank together with the cleaning wastewater and returning it to the pressure adjusting water tank, an outlet of the return pipe is disposed within the inlet passage of the pressure adjusting water tank; A filtering device, characterized in that a flow path cross-sectional area of ​​the inlet passage is set so that the speed of the water flow passing through the inlet passage is faster than the floating speed of the filter medium.

2. A filter medium detection means for detecting a filter medium floating on the water surface of the cleaning drainage tank; 2. The filtering device according to claim 1, further comprising a control means for operating the pump to circulate the filter medium when the filter medium detection means detects that the filter medium is present in an amount equal to or greater than a predetermined amount.

3. The water supply system includes a plurality of sets of the filtration tank and the pressure adjusting tank, The discharge portions of the respective filtration tanks are connected to a common cleaning drain tank, The control means includes an outflow information acquisition means for acquiring outflow information related to the amount of filter media outflowed from the filter media layer of each of the filtration tanks; The filtration device as described in claim 2, further comprising an adjustment means for adjusting the amount of filter media that has flowed into the cleaning wastewater returned to each of the filtration tanks based on the outflow information acquired by the outflow information acquisition means so as to prevent unevenness in the thickness of the filter media layer in each of the filtration tanks.

4. A light detection means is provided for detecting the thickness of the filter layer of each of the filtration tanks by light, 4. The filtration device according to claim 3, wherein the outflow information acquisition means acquires outflow information of the filter media in each of the filtration tanks from the thickness of each of the filtration layers detected by the light detection means.

5. In each of the multiple sets of filtration tanks and pressure-regulating tanks, a water level difference detection means is provided for detecting the water level difference between the water level of the treated water introduced into the pressure-regulating tank and the water level of the filtration tank when the filtration process is resumed after the backwash process and the inflow rate of the treated water is made constant; The filtration device described in claim 3, wherein the outflow information acquisition means calculates a filtration loss resistance of each filtration tank based on the water level difference detected by the water level difference detection means, and further acquires outflow information of the filter media of each filtration tank from the thickness of the filter media layer of each filtration tank calculated based on the filtration loss resistance.

6. The filtration device according to any one of claims 1 to 5, wherein the pump is a float pump.

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