JP2011104549A - Filtration system and filtration method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filtration system of which a filter medium is easily back-washed. <P>SOLUTION: The filtration system is for obtaining treated water by filtering object water and includes a filtration apparatus having a filter medium, an ejector for suctioning treated water from the filtration apparatus by generating negative pressure by operating water, and a back-washing means for backward passing the operating water to back-wash the filter medium by closing the flow channel in the discharge side of the ejector. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a filtration system and a filtration method using a particulate material such as sand or a membrane as a filter medium.

  A filtration method that captures and separates SS components, etc., with a filter medium through the water to be treated containing suspended substances (SS component), etc., through a filtration device having particulate matter such as sand or a membrane as a filter medium is for solid-liquid separation. It is known as a general technique. The sand filtration method using sand as the filter medium is an extremely simple filtration method, but as the filtration treatment time elapses, SS components, etc. in the water to be treated are trapped in the gaps of the filter medium, etc., gradually clogging, filtration flow rate and filtration performance Reduction may occur.

  Also, if the concentration of SS component, etc. of the water to be treated is high, or if the water to be treated contains a lot of highly viscous SS components, etc., a mud cake layer is formed on the surface of the filter medium to become an impermeable layer, Again, the filtration flow rate and filtration performance may be reduced.

  In order to eliminate such a blockage state, the filtration process is stopped after a predetermined filtration process time, and the filter medium is appropriately washed to recover its function. Normally, the SS component adhering to the surface of the filter medium or the gap is separated and floated from the filter medium by so-called reverse cleaning, in which the wash water is passed through the filtration device in the direction opposite to the water flow direction in the filtration process. To recover the filtration function.

JP 2008-000720 A

  Backwashing usually takes a lot of time and work, and there is a need for a filtration system and a filtration method that can perform backwashing efficiently. In addition, it is well known that effective reverse cleaning can be performed when air and cleaning water are used in combination for reverse cleaning, but conventionally, equipment such as a compressor has been separately required.

  The present invention is a filtration system and a filtration method that use particulate matter such as sand or a membrane or the like as a filter medium, which can easily backwash the filter medium.

  The present invention is a filtration system for filtering treated water to obtain treated water, a filtration device having a filter medium, and an ejector that draws treated water from the filtration device by generating a negative pressure by driving water. And a reverse cleaning means for reversely cleaning the filter medium by closing the flow path on the discharge side of the ejector to reversely flow the driving water.

  Moreover, it is preferable that the filtration system further includes a circulation unit that circulates at least part of the treated water and driving water discharged from the ejector and uses the circulating water as driving water for the ejector.

  In the filtration system, it is preferable that two or more filtration devices are connected in series or in parallel as the filtration device, and each of the filtration devices has one or more filter media.

  Further, the present invention is a filtration method for obtaining treated water by filtering the treated water, wherein the treated water is drawn by using a filter medium while sucking the treated water by an ejector that generates negative pressure by driving water. The filtration method includes a filtration step of performing a filtration treatment to obtain treated water, and a reverse washing step of backwashing the filter medium by causing the driving water to flow backward by closing a flow path on the discharge side of the ejector.

  In the present invention, in a filtration method for obtaining treated water by filtering treated water using a filter medium while sucking treated water with an ejector that generates negative pressure by driving water, the discharge-side flow path of the ejector is closed. Thus, it is possible to provide a filtration system and a filtration method that can easily perform reverse cleaning of the filter medium by reversely cleaning the filter medium by causing the drive water to flow backward.

It is a schematic structure figure showing an example of a filtration system concerning an embodiment of the present invention. It is a schematic block diagram which shows an example of the ejector in the filtration system which concerns on embodiment of this invention. It is the schematic which shows the mode of the flow of the drive water at the time of backwashing in the ejector of the filtration system which concerns on embodiment of this invention, and air. It is a schematic block diagram which shows the other example of the filtration system which concerns on embodiment of this invention. It is a schematic block diagram which shows the other example of the filtration system which concerns on embodiment of this invention. It is a schematic block diagram which shows the filtration system used in the Example of this invention.

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

  A schematic configuration of an example of a filtration system according to an embodiment of the present invention is shown in FIG. 1, and the configuration will be described. The filtration system 1 includes a filtration device 12 having a particulate material as a filter medium, and an ejector 14 that has an intake port 42 for sucking a gas, generates negative pressure by driving water, and sucks treated water from the filtration device 12. Prepare. The ejector 14 also functions as a reverse cleaning means for back-cleaning the filter medium by closing the flow path on the discharge side of the ejector 14 and causing the drive water to flow backward together with the gas sucked from the intake port 42. The filtration system 1 may include a water tank 10 to be treated on the upstream side of the filtration device 12.

  In the filtration system 1 of FIG. 1, the water pipe 24 to be treated is connected to the inlet of the water tank 10 to be treated, and the outlet of the water tank 10 to be treated is connected to the top of the filtration device 12 via the valve 16 by the water pipe 26 to be treated. Connected to the entrance. The lower outlet of the filtration device 12 is connected to the suction port 44 of the ejector 14 via the valve 18 by the treated water pipe 28, and the outlet on the discharge side of the ejector 14 is connected to the outlet 20 via the valve 20 that also functions as a reverse cleaning means. The treated water piping 30 is connected. A drive water pipe 46 is connected to the drive water inlet of the ejector 14. A backwash water discharge pipe 32 is connected to the upper part of the filtration device 12 via a valve 22. From the outlet of the water tank 10 to be treated of the filtration system 1 to the suction port 44 of the filtration device 12 and the ejector 14, a sealed structure is provided by valves 16, 18, and 22.

  The filtration device 12 is a downward flow type filtration tower having a particulate material, a membrane, or the like as a filter medium. The filtration device 12 includes, for example, at least one filtration layer 36 configured to contain a particulate material as a filter medium. The filtration layer 36 is provided between screen members 38 and 40 having a mesh smaller than the particle size of the particulate material, and includes a particulate material having a coarser particle diameter than the particulate material of the filtration layer 36 on the front side of the filtration layer 36. You may have the prefiltration layer 34 comprised by these.

  To-be-treated water including suspended substances (SS component) and the like is treated and stored in the to-be-treated water tank 10 through the to-be-treated water pipe 24 as necessary. When the valve 22 is closed and the valves 16, 18, 20 are opened, and the drive water is supplied to the drive water inlet of the ejector 14 through the drive water pipe 46 at a predetermined flow rate and drive pressure, negative pressure is generated. Then, the water to be treated passes through the water pipe 26 to be treated and is sent to the filtration device 12.

  In the filtration device 12, the water to be treated passes through the prefiltration layer 34 and the filtration layer 36 in a downward flow, and SS components and the like contained in the water to be treated are captured and separated by the filtration layer 36 to obtain treated water. (Filtration step). The treated water is sucked into the ejector 14 from the suction port 44 through the treated water pipe 28 from the lower outlet of the filtration device 12, and together with the drive water from the outlet on the discharge side of the ejector 14 through the treated water pipe 30. Discharged.

  FIG. 2 is a schematic configuration diagram illustrating an example of the ejector 14 in the filtration system according to the embodiment of the present invention. The ejector 14 is provided on the inlet side of the main pipe 60 having a cylindrical shape or the like, the nozzle 62 having an outlet inner diameter smaller than the inlet inner diameter for introducing driving water, an inlet side of the main pipe 60, Gas provided between the outlet side and the inlet port 44 for sucking in the treated water, and between the inlet port 44 and the inlet side of the main pipe 60 and downstream of the outlet of the nozzle 62. And an intake port 42 for sucking air. The ejector 14 may have a cavityless tube 64 that is a cylindrical tube having an inner diameter D that is located a predetermined distance L away from the outlet of the nozzle 62 and has an inner diameter D that is larger than the inner diameter d of the outlet of the nozzle 62. Good.

  In the ejector 14, when driving water is introduced from the inlet side of the ejector 14, the driving water passes through the nozzle 62 whose diameter is narrowed inside and is jetted as a high-pressure jet from the outlet of the nozzle 62. In the high-pressure jet jet ejected from the nozzle 62, the jet core diffuses as it advances in the straight direction, and its momentum diffuses and becomes thin. However, the air sucked from the intake port 42 in the cabless tube 64 is the jet core. While maintaining the momentum with almost no reduction in the flow velocity with the air flow caused by the vacuum region formed around the water, it goes straight to the suction port 44 side to form a new negative pressure suction region, Sucked. That is, the cabless tube 64 has a nozzle function of a jet (a mixed fluid of gas (air etc.) and liquid (driving water)), and can maintain a stable suction performance.

  For example, when driving water is jetted from the nozzle 62 as a high-pressure jet at a high speed with a driving pressure of 3 MPa or more, a negative pressure close to vacuum is generated at the outlet (jet port) of the nozzle 62. In general, when a high-pressure jet is injected in a closed pipe, turbulent flow is generated around the nozzle injection port (also called cavitation phenomenon), which may damage components and obstruct the straight flow of the jet. Therefore, the air inlet 42 is provided as in the present embodiment, and the outside air is sucked from the air inlet 42 to prevent the occurrence of cavitation phenomenon and the diffusion of the jet flow.

  The filtration rate can be increased by generating a negative pressure using an ejector-type device and suctioning the filtration device with a negative pressure. Further, by adopting an ejector type device as a negative pressure suction means for generating a negative pressure, aeration of treated water is promoted by a suction function of the ejector. Furthermore, even when harmful volatile substances such as volatile organic compounds (VOC) are mixed in the water to be treated, vaporization of the volatile substances is promoted by the negative pressure generating function of the ejector. For example, when drinking water is secured by this system, if sterilization is performed by mixing a volatile disinfectant such as chlorine gas on the front side of the filtration device 12 and then processing is performed by this system, the negative load of the ejector Residual volatile substances such as residual chlorine in the treated water can be reduced by the pressure generation function.

  After performing the filtering process for a predetermined time, the filter medium of the filtering device 12 is back-washed. When the valves 16 and 18 in FIG. 1 are opened, the valve 22 is closed, the valve 20 on the discharge side of the ejector 14 that sucks treated water is closed, and the ejector 14 is operated, the drive water and the intake 42 are sucked. As shown in FIG. 3, the air flows back through the treated water pipe 28 from the suction port 44, and the jet cleaning of the filter medium is performed in the filtration device 12 of FIG. 1 (reverse cleaning step). The filter medium is agitated by the jet between the screen members 38 and 40, and the SS component and the like adhering to the surface of the filter medium and the gap are separated, and the SS component and the like are floated and separated through the mesh of the screen member 38. The SS component floated and separated is discharged through the backwash water discharge pipe 32 by closing the valve 16 and opening the valve 22, and the filtration function is restored. At this time, it is preferable to open the valves 18 and 22 so as to reduce the water pressure and to discharge the floating separation from the backwash water discharge pipe 32 as quietly as possible.

  When the floating separator is almost recovered, when the ejector 14 is stopped, when the filter medium is a granular material, the filter medium settles down due to gravity and becomes a laminated state. At this time, when the filtration layer 36 is configured using one type of filter medium without providing the pre-filtration layer 34, the filter medium settles down due to gravity and is almost in the original laminated state. For example, when the filter layer 36 or the pre-filter layer 34 and the filter layer 36 are configured with the filter medium having a heavy weight as the upper layer and the filter medium having the small weight as the lower layer, the filter medium settles from the filter medium with the heavy weight after the reverse cleaning is completed. There is a case where the filter medium is in a layered state opposite to the original before washing. In this case, the main body of the filtration device 12 can be turned upside down so that the layered state can be substantially restored.

  Thus, by using the ejector type apparatus for negative pressure suction not only for suction at the time of filtration but also for backwashing, no additional equipment such as a compressor is required. Even when the filtration medium becomes clogged with the SS component in the water to be treated and the filtration flow rate is reduced with the passage of the filtration process time, the filter medium surface, gaps, etc. The SS component adhering to is peeled off and washed, and the filtration function is restored. In addition, even when the slurry concentration of water to be treated is high, or when a lot of highly viscous SS components are contained, even if a mud cake layer is formed on the surface of the filter medium and becomes an impermeable layer, The filtration function is restored by backwashing efficiently with a short backwashing treatment time.

  Although the filtration apparatus 12 is a substantially downward flow type filtration tower having a particulate material as a filter medium, it may be of a substantially upward flow type and is not particularly limited. Usually, a shape having a straight body portion can be used, but flexible piping may be used, for example, piping that can withstand negative pressure may be used.

  Examples of the filter medium include particulate substances, membranes, screens, and the like, and any material that can capture and separate suspended substances such as SS components from the water to be treated is not particularly limited. What is necessary is just to select a filter medium according to the property of the to-be-processed water used as a process target, properties, such as contained SS component. As the particulate material, anthracite, garnet, activated carbon, zeolite and the like can be used in addition to sand. As the membrane and the screen, for example, a flat membrane or a flat plate having an opening of about several mm to (several / 100) mm can be used, and a hollow fiber membrane, a spiral membrane, a tubular membrane or the like is used. Also good. Further, a microfiltration membrane (MF membrane), an ultrafiltration membrane (UF membrane), a reverse osmosis membrane (RO membrane), or the like may be used.

  The particle size of the particulate material may be selected according to the properties of the water to be treated, the properties of the contained SS component, etc., and is not particularly limited. Usually, for example, a material in the range of several mm to (several / 10) mm may be used.

  Moreover, you may use as a multilayer structure which laminated | stacked two or more filtration layers of the granular material of a different kind and particle size, and it is good also as a filtration layer by mixing two or more granular materials of a different kind and particle size. For example, by subjecting sand as a filter medium to sand filtration and then performing zeolite treatment or the like, water to be treated containing harmful substances can be treated to a discharge level or the like.

  As the filtering device 12, two or more filtering devices may be connected in series and used, or two or more filtering devices may be connected in parallel. For example, as shown in FIG. 5 described later, two or more filtration devices each having one filter medium of the same type or different types may be connected in series or used in parallel. . Again, at least one of the two or more filtration devices can be backwashed as described above. If two or more filtration devices are connected in series, the filtration process can be performed step by step for each required filtration function. Filters containing filter media with different filtration functions, filter flow rate, device inner diameter (effective cross-sectional area in the flow line direction of the filter media), filter layer thickness, type and particle size of particulate matter, type of filter membrane / screen, They can be used by being connected in an effective order by changing the mesh opening or the like. Further, by using two or more filtration devices connected in series or in parallel, for example, in one or more filtration devices, clogging of the filter medium occurs, the filtration flow rate decreases, When backwashing or replacement becomes necessary, it is possible to efficiently perform filtration by detouring the filtration device, etc., and clogged filter media can be easily replaced. .

  The screen members 38 and 40 are used when the filter medium is a particulate material, and may have any mesh that is smaller than the particle size of the particulate material. Examples thereof include those made of metal and resin. In order to perform reverse cleaning efficiently, the size of the mesh of the screen members 38 and 40 may be, for example, about 0.25 mm to 1 mm.

  Even if it has the to-be-processed water tank 10 which stores a to-be-processed water in the front | former stage side of the filtration apparatus 12, it does not need to be provided. The water tank 10 to be treated may be provided, and the SS concentration of the water to be treated may be adjusted in the water tank 10 to be treated.

  The ejector 14 is not limited to the above-described method and is not particularly limited as long as it generates a negative pressure by driving water. The ejector 14 may have an intake port for sucking a gas as shown in FIGS. 2 and 3 or may not have an intake port. Even if the intake port is not provided, the filter medium can be backwashed by causing the drive water to flow backward by closing the flow path on the discharge side of the ejector. When the intake port is provided, air and cleaning water can be used in combination for back cleaning, and more effective back cleaning can be performed. Further, as described above, the ejector 14 is a vacuum suction pump for the water to be treated of the filtration device 12 and also serves as a jet pump for back-cleaning the filter medium.

  By the ejector 14, the pressure inside the filtration device 12 is reduced to, for example, about 0.01 MPa to 0.02 MPa.

  The drive water of the ejector 14 is not limited to water but may be liquid, but is usually water. Driving water may be prepared separately, or at least a part of the treated water may be circulated and used as will be described later.

  In the ejector 14, the gas sucked from the air inlet 42 is, for example, air, bactericidal gas such as chlorine gas, ozone, or the like, but is usually air (outside air). When a sterilizing gas such as chlorine gas or ozone is used as the gas sucked from the air inlet 42, the treated water can be sterilized easily.

  The inner diameter D of the cavityless tube 64 shown in FIG. 2 may be, for example, 2.5 to 5 times the inner diameter d of the outlet of the nozzle 62. Further, the distance L from the outlet of the nozzle 62 to the inlet of the cabless tube 64 may be, for example, 5 to 10 times the inner diameter d of the outlet of the nozzle 62.

  In the vacuum suction type filtration system 1 as shown in FIG. 1, a negative pressure is generated using the ejector 14, and the treated water from the filtration device 12 is discharged together with the drive water of the ejector that sucks the treated water. As shown in FIG. 4, the treated water from the filtration device 12 may be circulated together with the driving water discharged from the ejector 14 and used as the driving water for the ejector 14.

  In FIG. 4, schematic structure of the other example of the filtration system which concerns on embodiment of this invention is shown. In addition to the system configuration of FIG. 1, the filtration system 3 circulates at least a part of the treated water tank 48, treated water and drive water discharged from the ejector 14, and uses the circulating water as drive water for the ejector 14. And a pump 52.

  In the filtration system 3 of FIG. 4, the outlet of the ejector 14 of the treated water pipe 30 and the valve 20 and the inlet of the treated water tank 48 are connected via the valve 50 by the treated water pipe 54. The treated water tank 48 is connected to the drive water pipe 46 by a circulating water pipe 56 via a pump 52.

  To-be-treated water including suspended substances (SS component) and the like is treated and stored in the to-be-treated water tank 10 through the to-be-treated water pipe 24 as necessary. When the valve 22 is closed and the valves 16, 18, 20, 50 are opened, and the drive water is supplied to the drive water inlet of the ejector 14 through the drive water pipe 46 at a predetermined flow rate and drive pressure, a negative pressure is generated. The water to be treated passes through the water pipe 26 to be treated and is fed to the filtration device 12.

  In the filtration device 12, the water to be treated passes through the prefiltration layer 34 and the filtration layer 36 in a downward flow, and SS components and the like contained in the water to be treated are captured and separated by the filtration layer 36 to obtain treated water. (Filtration step). The treated water is sucked into the ejector 14 from the suction port 44 through the treated water pipe 28 from the lower outlet of the filtration device 12, and together with the drive water from the outlet on the discharge side of the ejector 14 through the treated water pipe 30. Discharged. Here, at least a part of the treated water and the drive water discharged from the ejector 14 is stored in the treated water tank 48 through the treated water pipe 54. The treated water and the drive water stored in the treated water tank 48 are circulated and supplied at a predetermined flow rate and drive pressure to the drive water inlet of the ejector 14 as drive water for the ejector 14 through the circulating water pipe 56 by the pump 52 ( Circulation process).

  After performing the filtering process for a predetermined time, the filter medium of the filtering device 12 is back-washed. When the ejector 14 is operated with the valves 16 and 18 in the open state, the valve 22 in the closed state, and the valves 20 and 50 on the discharge side of the ejector 14 that sucks the treated water in the closed state, the drive water and the intake port 42 are sucked. The air flows back through the treated water pipe 28 from the suction port 44, and the filter medium is jet-washed in the filtering device 12 (back washing process). The SS component floated and separated is discharged through the backwash water discharge pipe 32 by closing the valve 16 and opening the valve 22, and the filtration function is restored. Also in the filtration system 3 of FIG. 4, the ejector 14 may have an intake port for sucking gas as shown in FIGS. 2 and 3 or may not have an intake port. Even if the intake port is not provided, the filter medium can be backwashed by causing the drive water to flow backward by closing the flow path on the discharge side of the ejector.

  As described above, the treated water is circulated together with the drive water discharged from the ejector 14 and is used as the drive water for the ejector 14, whereby the filtration process can be performed more efficiently.

  In FIG. 5, schematic structure of the other example of the filtration system which concerns on embodiment of this invention is shown. The filtration system 5 includes three filtration devices 12a, 12b, and 12c connected in series as filtration devices.

  In the filtration system 5 of FIG. 5, the outlet of the water tank 10 to be treated is connected to the inlet of the upper part of the filtration device 12 a via the valve 16 by the water pipe 26 to be treated. The lower outlet of the filtration device 12a is connected to the upper inlet of the filtration device 12b via the valve 18a by the treated water piping 28a, and the lower outlet of the filtration device 12b is filtered to the filtration device 12c via the valve 18b by the treated water piping 28b. The lower outlet of the filtration device 12c is connected to the suction port 44 of the ejector 14 through the valve 18c by the treated water pipe 28c, and the outlet on the discharge side of the ejector 14 also functions as a back cleaning means. The treated water piping 30 is connected through the valve 20 to be used. Backwash water discharge pipes 32a, 32b, and 32c are connected to the upper portions of the filtration devices 12a, 12b, and 12c via valves 22a, 22b, and 22c, respectively. From the outlet of the water tank 10 to be treated of the filtration system 1 to the filtration devices 12a, 12b, 12c and the suction port 44 of the ejector 14, a sealed structure is provided by valves 16, 18a, 18b, 18c, 22a, 22b, 22c.

  The filtration devices 12a, 12b, and 12c are downward flow type filtration towers having a particulate material, a membrane, or the like as a filter medium. The filtration devices 12a, 12b, and 12c include, for example, one filtration layer 36a, 36b, and 36c each including a particulate material as a filter medium. The filtration layers 36a, 36b, and 36c are provided between the screen members 38a and 40a having a mesh smaller than the particle size of the particulate material, between 38b and 40b, and between 38c and 40c, respectively. For example, the filtration layer 36a on the most upstream side is a gravel layer including a granular material having a coarse particle size, and the filtration layer 36b on the downstream side contains a granular material having a particle size finer than that of the gravel layer. It is a sand filtration layer comprised including, and the most downstream filtration layer 36c is a zeolite layer comprised including zeolite. The respective filter media possessed by the filtration devices 12a, 12b, and 12c may be of different types or of the same type. In the example of FIG. 5, there are three filtration devices, but it is sufficient that there are two or more, and the number of filtration devices to be connected is not particularly limited.

  To-be-treated water including suspended substances (SS component) and the like is treated and stored in the to-be-treated water tank 10 through the to-be-treated water pipe 24 as necessary. With the valves 22a, 22b, and 22c closed and the valves 16, 18a, 18b, 18c, and 20 opened, the drive water passes through the drive water piping 46 to the drive water inlet of the ejector 14 at a predetermined flow rate and drive pressure. When supplied, negative pressure is generated, and the water to be treated passes through the water pipe 26 to be treated and is sent to the filtration device 12a.

  For example, in the filtration device 12a, the water to be treated passes through the filtration layer 36a in a downward flow and is pretreated. In the next filtration device 12b, the water to be treated passes through the filtration layer 36b in a downward flow, and SS components and the like contained in the water to be treated are captured and separated by the filtration layer 36b. In the next filtration device 12c, the water to be treated passes through the filtration layer 36c in a downward flow, and harmful substances and the like are captured by the zeolite layer to obtain treated water (filtration process). The treated water is sucked into the ejector 14 from the suction port 44 through the treated water pipe 28 c from the lower outlet of the filtration device 12 c, and together with the drive water through the treated water pipe 30 from the outlet on the discharge side of the ejector 14. Discharged.

  After performing the filtration process for a predetermined time, the filter medium 12a, 12b, 12c is subjected to a reverse cleaning process. When the ejector 14 is operated with the valves 16, 18 a, 18 b, 18 c open, the valves 22 a, 22 b, 22 c are closed, and the discharge valve 20 of the ejector 14 that sucks treated water is closed, driving water and intake air The air sucked from the port 42 flows back through the treated water pipes 28c, 28b, 28a from the suction port 44, and the filter medium is jet-washed in the filtering devices 12c, 12b, 12a (reverse cleaning step). The SS component that has been floated and separated is discharged through the backwash water discharge pipes 32a, 32b, and 32c, respectively, by closing the valve 16 and opening the valves 22a, 22b, and 22c, thereby restoring the filtration function. The In the filtration system 5 of FIG. 5, the ejector 14 may have an intake port for sucking a gas as shown in FIGS. 2 and 3, or may not have an intake port. Even if the intake port is not provided, the filter medium can be backwashed by causing the drive water to flow backward by closing the flow path on the discharge side of the ejector.

  In this way, if two or more filtration devices are connected in series, the filtration process can be performed step by step for each required filtration function. Filters containing filter media with different filtration functions, filter flow rate, device inner diameter (effective cross-sectional area in the flow line direction of the filter media), filter layer thickness, type and particle size of particulate matter, type of filter membrane / screen, They can be used by being connected in an effective order by changing the mesh opening or the like.

  The filtration system according to the present embodiment can be used for any water purification treatment. Examples of water to be treated include muddy water after washing sand in sandboxes, muddy water after washing soil in vegetable gardens, muddy water in ponds, etc., but are not limited thereto. is not. For example, various muddy water treatments from the discharge level to the securing of drinking water are possible. Further, the filtration system according to the present embodiment can be designed in a compact manner, and can be a mobile type system that can be mounted on a vehicle such as a truck.

  Moreover, you may install an advanced water treatment apparatus by the back | latter stage side of the filtration system which concerns on this embodiment for the utilization as drinking water, the removal of a harmful substance, etc.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely in detail, the present invention is not limited to the following examples.

<Example 1>
Using the filtration system shown in FIG. 6, the filtration treatment and the back washing effect were confirmed. The experimental conditions are as follows.

[Experimental conditions]
Volume of the main body of the filtration device 12: 30L
Horizontal cross-sectional area of the main body of the filtration device 12: 637.6 cm ²
Filter sand used for the filter layer 36: coarse sand having a particle size of 1 mm to 2 mm Thickness of the filter layer 36: 20 cm
Volume of the filtration layer 36: 12.7L
Pre-filtration layer 34: Cured gravel on the upper part of the filtration layer 36 (particle size 5 to 10 mm) (provided in the case of processing a sample slurry of 0.75% concentration)
The thickness of the prefiltration layer 34: 5 cm
Distance from the upper end of the filtration layer 36 to the upper end of the main body of the filtration device 12: 20 cm
Drive pressure of ejector 14: 4 Mpa
Ejector 14 drive water volume: 30 L / min Sample slurry (water to be treated) SS concentration: 0.75% and 0.2% Sample slurry water injection method: First, 6 L sample slurry is injected at intervals of 30 seconds Then, when the water level of the sample liquid dropped to 10 cm from the upper end of the main body of the filtration device 12, water was poured and the interval was recorded.
Filtration flow rate measurement method: The time required for a 5 cm drop in water level was recorded every 5 minutes.
Confirmation of backwashing effect: When the filtration flow rate is 50% of the planned flow rate (5 m / h), close the valve 20 and back pump, perform backwashing for 3 minutes, repeat the experiment again, confirmed.

[Measurement result]
Table 1 shows the measurement results. In the case of a sample slurry having a concentration of 0.75%, since a mud cake layer was formed on the surface of the filtration layer 36 in about 5 to 10 minutes, 5 to 10 mm diameter gravel was spread on the surface of the filtration layer 36 with a thickness of 5 cm. , Prevented the formation of a mud cake layer. In the 0.2% sample slurry, a mud cake layer was hardly formed at the test time (30 minutes).

  As shown in Table 1, a sufficient recovery of the filtration function could be confirmed by back washing for 3 minutes. In addition, after reverse cleaning, a phenomenon was observed in which part of the gravel layer on the surface was buried in the filter sand material by jet stirring and cleaning, and the experiment was resumed by replenishing gravel after reverse cleaning.

  Thus, it was confirmed that the filter medium can be efficiently backwashed in a short backwashing treatment time with a simple apparatus configuration, and the filter function of the filter medium is restored.

  1,3,5 filtration system, 10 treated water tank, 12, 12a, 12b, 12c filtration device, 14 ejector, 16, 18, 18a, 18b, 18c, 20, 22, 22a, 22b, 22c, 50 valve, 24 26, treated water piping, 28, 28a, 28b, 28c, 30, 54 treated water piping, 32, 32a, 32b, 32c backwash water discharge piping, 34 pre-filtration layer, 36, 36a, 36b, 36c filtration layer, 38, 38a, 38b, 38c, 40, 40a, 40b, 40c Screen member, 42 Intake port, 44 Suction port, 46 Drive water piping, 48 Treated water tank, 52 Pump, 56 Circulating water piping, 60 Main pipe, 62 Nozzle, 64 A cabless tube.

Claims (4)

A filtration system for obtaining treated water by filtering treated water,
A filtration device having a filter medium;
An ejector that generates negative pressure by driving water and sucks treated water from the filtration device;
Backwashing means for backwashing the filter medium by backflowing the drive water by closing the discharge-side flow path of the ejector;
A filtration system comprising: The filtration system according to claim 1,
A filtration system further comprising a circulation means for circulating at least a part of treated water and driving water discharged from the ejector and using the circulating water as driving water for the ejector. The filtration system according to claim 1 or 2,
Two or more filtration devices are connected in series or in parallel as the filtration device, and each of the filtration devices has one or a plurality of filter media. A filtration method for obtaining treated water by filtration of treated water,
A filtration step of obtaining treated water by filtering the treated water using a filter medium while sucking the treated water with an ejector that generates negative pressure by driving water;
A backwashing step of backwashing the filter medium by backflowing the driving water by closing the flow path on the discharge side of the ejector;
The filtration method characterized by including.

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