JP3815615B2 - High-speed filtration device using fiber filter media - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to improvement of untreated sewage in rainy weather by a high-speed filtration device using a floatable synthetic resin fiber filter medium.
[0002]
[Prior art]
Conventionally, a filtering device using a levitating filter medium having a specific gravity of 1.0 or less is provided with a screen for preventing the loss of filter medium in the upper part of the filtration tank, and a filter medium layer is formed by loading a levitating filter medium below the screen. However, the raw water is passed in an upward flow for filtration, and when washing the filter medium, the washing water is supplied to the filter medium layer, and air is supplied from the lower part of the filter medium layer to stir and wash the filter medium. Are known. The invention described in Patent Document 1 is an example. In the present invention, in order to remove high-concentration SS in wastewater, a method of capturing SS in a gap between filter media using a hollow cylinder type or spherical floatable filter media having different diameters and specific gravity. In the present invention, a filtration rate of 50 to 250 m / day is achieved with wastewater having an SS concentration of 600 mg / L. In addition, sand filtration devices have been conventionally used as a method for removing SS of low-concentration wastewater, but in recent years, a filtration method using a fiber filter medium that captures SS by gaps between fibers has been performed. The inventions described in Patent Document 2 and Patent Document 3 are examples.
[0003]
In the invention of Patent Document 2, a fiber filter medium composed of heat-fusible fibers is used, and a filtration rate of 900 m / day is obtained by passing a low concentration raw water with an SS concentration of 5 mg / L in a downward flow. Has achieved. In the invention of Patent Document 3, a fiber bundle in which two types of heat-fusible fibers having different melting points are mixed together is heat-treated, and a rod-shaped fiber bundle molded body having a feather-like surface cut is used as a filter medium. The activated sludge-treated wastewater is used as raw water and water is passed in a downward flow to achieve a filtration rate of about 800 m / day. All of these fiber filter media are treated for 5 to 10 mg / L of raw water having a relatively low concentration, such as sewage secondary treated water, and the water is passed in a downward flow for 800 to 900 m / day. The maximum filtration rate is achieved, high-speed filtration 3 to 4 times that of sand filtration is possible, and the SS removal rate is also high.
[0004]
[Patent Document 1]
JP 2001-219209 A [Patent Document 2]
Japanese Patent Laid-Open No. 11-262609 [Patent Document 3]
Japanese Patent Laid-Open No. 11-151405
[Problems to be solved by the invention]
However, in the conventional filtration method described above, a fiber filter medium is used as described in Patent Document 2 and Patent Document 3 for low-concentration raw water such as sewage secondary treated water. For such high-concentration raw water, a spherical or cylindrical filter medium as described in Patent Document 1 is used, and an appropriate filter medium is selected for the raw water to be treated. Needed to be used. Therefore, if the filter medium for high-concentration raw water is used for the treatment of low-concentration raw water, or if the filter medium for low-concentration raw water is used for the treatment of high-concentration raw water, the filtration rate decreases or the turbidity of the treated water increases. There is a problem. On the other hand, in a large city where sewerage has been popular for a long time, a combined sewer system in which sewage and rainwater flow through the same pipe is often used. However, in this combined sewer, a large amount of rainwater flows into the treatment plant during heavy rain, and the sewage that exceeds the treatment capacity of the treatment plant is discharged into the public water area without being treated, causing water pollution. This is a social problem. If it can be processed at high speed with the filter medium for high-concentration raw water described in Patent Document 1, it can be used for the above-mentioned untreated water during rainy weather. There is also a problem that it cannot be effectively used throughout the year because it is not so many.
[0006]
[Means for Solving the Problems]
The present invention solves the above-described problems of the prior art, and the gist of the present invention is that a filter medium layer is formed by filling a processing tank having a filter medium loss prevention screen stretched thereon with a floatable fiber filter medium. In a filtration tank that performs filtration in an upward flow, a dividing plate made of a perforated plate that divides the filtration tank into a plurality of equal parts is suspended, and a foamable resin is used as a fiber filter medium that forms the filter medium layer High speed using a fiber filter medium that uses a plate that is made by sandwiching a plurality of synthetic resin fibers with different fiber diameters and pasting them together , and adjusting the specific gravity to 0.2 to 0.8. A filtration device, wherein the fiber filter medium is a non-woven fiber filter medium composed of three types of synthetic resin fibers having different fiber diameters, and the first filament is a heat-fusible composite fiber having a polypropylene core coated with polyethylene. There is a fineness of 18-65 denier The second filament is a polypropylene fiber with a fineness of 3 to 10 denier, and the third filament is a heat-fusible composite fiber with a polypropylene core coated with polyethylene and blends each fiber with a fineness of 1.5 to 6 denier the web is fabric formulated by needle punching method has the web brushed state by heat treatment without smoothing the plate body causes Awa bonded across the foamable resin plate in said plate member, 3 is the thickness A 30 mm, a width of 5 to 30 mm and a length of 5 to 30 mm are cut into a rectangular or cubic shape.
[0007]
Then, a pretreatment device is provided in the preceding stage of the filtration tank, and after removing impurities using any one of a gravity precipitation device, a coarse filtration device, or a screen device as the pretreatment device, the filtration is performed. Of these pretreatment devices, the coarse filtration device uses a resin floating hollow cylindrical filler having a diameter of 5 to 20 mmΦ and a length of 10 to 30 mm. The apparatus is a high-speed filtration apparatus using a fiber filter medium using a screen in which a porous plate having a pore diameter of 1 to 10 mmΦ is stretched.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The apparatus which concerns on this invention is comprised as mentioned above, and can use the first sedimentation place in the terminal treatment plant of a combined sewer as a filtration tank. The filtration device of the present invention may be installed alone, or may be installed using a part of the existing first sedimentation site. Hereinafter, the case where raw water is treated using the first sedimentation site as a filtration tank will be described. A filter tank made of concrete is equally divided into multiple rooms, a screen for preventing the loss of filter medium is stretched at the top of the filter tank, and each room is filled with an equal amount of the same type of floatable fiber filter medium. Form a layer. And the division | segmentation plate which divides each room | chamber of a filtration tank uses the perforated plate, Since this perforated plate passes water, but a fiber filter medium cannot pass, there is no fluctuation | variation of the amount of filter media between each room. The filter medium filled in this filtration tank is a non-woven fiber filter medium composed of three types of synthetic resin fibers with different fiber diameters, and the first filament is a heat-fusible composite fiber with a polypropylene core coated with polyethylene. There is a fineness of 18 to 65 denier, the second filament is polypropylene fiber and the fineness is 3 to 10 denier, and the third filament is a heat-fusible conjugate fiber with a polypropylene core coated with polyethylene and a fineness of 1. A web mixed with 5 to 6 denier fibers is made into a cloth by needle punching method, heat-treated without smoothing the web raised state, and a foamed resin plate is sandwiched between the plates. was Awa bonding to adjust the specific gravity to 0.2 to 0.8, a thickness of 3 to 30 mm, a width of 5 to 30 mm, length discretion the rectangular-shaped or cuboid 5 to 30 mm One in which the.
[0009]
In addition, when treating raw water containing high concentrations of untreated sewage in rainy weather, a pretreatment device is installed in front of the filtration tank to remove the impurities, and then the raw water is filtered through the filtration tank. It is something to process. The pretreatment device is a gravity precipitation device using the first half of the first settling basin as a settling tank, or the first half of the first settling basin is a coarse filtration tank with a diameter of 5 to 20 mmΦ and a length of 10 to 30 mm. Using a coarse filtration device that removes impurities by filling a resin-made floating hollow cylindrical filter medium into the coarse filtration tank, or a perforated plate having a pore diameter of 1 to 10 mmΦ was stretched at the inflow portion of the first sedimentation basin There is a screen device that removes impurities by a screen. Note that the pretreatment device is used when treating untreated sewage in rainy weather including contaminants, and since it filters low-concentration secondary treatment water during fine weather, it does not pass through the pretreatment device. In addition, the low concentration raw water is directly supplied to the filtration tank to perform the filtration treatment. In addition, since the high-speed filtration apparatus using the fiber filter medium of the present invention performs the treatment without chemical injection, equipment such as chemical injection equipment becomes unnecessary.
[0010]
If clogging occurs in the filter medium due to continued filtration operation and the processing capacity decreases, it is necessary to clean and regenerate the filter medium. The cleaning time of the filter medium is detected when the pressure loss reaches the set value or by the set value of the timer, and the water flow and air are used in combination for cleaning. The raw water can be used as it is for the filtration of the secondary treated water. In the case of the secondary treated water or combined rainwater, the treated water held in the upper part of the filtration tank is made to flow backward from the filter media prevention screen. You may wash. Whether to clean or regenerate the filter medium using either raw water or treated water can be selected depending on the target raw water or the like. In addition, after the filtration treatment of untreated water in rainy weather, in order to switch to filtration for secondary treated water, the filter medium is washed with secondary treated water before switching, and then the raw water is switched. To do. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0011]
【Example】
FIG. 1 is a flow sheet diagram of a high-speed filtration device according to the present invention, and high-concentration raw water containing impurities such as untreated sewage in rainy weather is removed by a pretreatment device 6 installed in the previous stage of the filtration tank 1. After the removal, the raw water is evenly supplied from the inverted U-shaped raw water supply tank 10 disposed in the lower part of the filtration tank 1, and the solid matter in the raw water is passed through the filter medium layer 3 in an upward flow. The treated water captured by the filter medium layer 3 and passed through the filter medium layer 3 is taken out from the upper part of the filter tank 1 to the outside. FIG. 2 shows a gravity precipitation device 6a among the pretreatment devices 6 installed in the preceding stage of the filtration tank 1, and high-concentration raw water containing impurities flows into the precipitation tank 9, and is contaminated in the precipitation tank 9. After the sediment is removed, the material is supplied into the filter tank 1 from the lower part of the filter tank 1 and passes through the filter medium layer 3 composed of the fiber filter medium 4 in an upward flow. At this time, the solid material contained in the raw water is captured by the filter medium layer 3 and flows into the upper portion of the filtration tank 1 as clear treated water, overflows from the treated water trough 11 and is discharged to the outside.
[0012]
FIG. 3 shows a coarse filtration device 6b of the pretreatment device 6, and high-concentration raw water containing contaminants enters the coarse filtration tank 12 from an inlet 14 provided at the lower part of the coarse filtration tank 12. Inflow. In the coarse filtration device 6b disposed in the coarse filtration tank 12, a filter medium layer is formed by a resin floating hollow cylindrical filler 7 having a diameter of 5 to 20 mmΦ and a length of 10 to 30 mm. The raw water flowing in from the inlet 14 ascends the filter medium layer. At this time, contaminants in the raw water are captured by the floating hollow cylindrical filler 7, pass through the floating hollow cylindrical filler 7 flow prevention screen 13, and flow into the filtration tank 1 provided therewith. About the process in the filtration tank 1, since it is the same as the process after the above-mentioned gravity precipitation apparatus, description is abbreviate | omitted. The floatable hollow cylindrical filler 7 uses a material having a specific gravity slightly smaller than that of water, and if impurities accumulate in the hollow cylinder, it becomes heavier than the specific gravity of water and settles downward. The contaminants in the hollow cylinder are peeled off by the collision between the filter media and the impact at the bottom, and rise again to form the filter media layer.
[0013]
FIG. 4 shows a screen device 6c of the pretreatment device 6. A high-concentration raw water containing impurities flows into the screen device 6c, and the raw water is fed by the screen 8 disposed in the screen device 6c. After the impurities are removed, it flows into the filtration tank 1. About the process in the filtration tank 1, since it is the same as the process after the above-mentioned gravity precipitation apparatus, description is abbreviate | omitted. FIG. 5 shows an embodiment of the screen device 6c and is a longitudinal sectional view of a cylindrical rotary automatic screen device. The raw water flows into a cylindrical screen 8 provided with a perforated plate such as a punching plate having a hole diameter of 1 to 10 mmΦ. Large solid matter such as foreign matters adheres to the inner surface of the screen 8, is scraped up by the scraper 16 rotating by the driving machine 19, and moves to the upper part. And it falls in the drainage trough 17 with the washing water spouted from the washing pipe 21 arranged in the upper part. The contaminants that have fallen on the drainage trough 17 are taken out from the discharge port 18, and the raw water that has passed through the screen 8 flows into the filtration tank 1 from the outlet 20. Since the cleaning water is jetted from the fixed cleaning pipe 21 while rotating the screen 8, the amount of cleaning water in the screen 8 can be very small.
[0014]
If the filtration process as described above is continued, the fiber filter medium 4 will be clogged with foreign substances and the processing capacity will be reduced. Therefore, the fiber filter medium 4 needs to be washed and regenerated. The cleaning time is detected by a pressure rise in the filtration tank 1 or a timer, and air is supplied into the filtration tank 1 from the air supply pipe 24 in FIG. The washing water to be used can be washed with raw water, but it is also possible to wash the filtered water held in the upper part of the filtration tank 1 by flowing it back from the screen 2 and can be selected depending on the installation conditions. Is. Then, after the sewage treatment in rainy weather, before the switching to the filtration of the secondary treated water, the fiber filter medium 4 is washed again with the secondary treated water, and then the raw water is switched. The cleaning wastewater is collected in the cleaning drainage tank 23 from the cleaning drainage water collecting pipe 22 disposed in the lower part of the filtration tank 1.
[0015]
Next, the fiber filter medium 4 used in the embodiment of the filtration device of the present invention will be described in detail with reference to FIG. The fiber filter medium 4 is a rectangular parallelepiped having a thickness of 3 to 30 mm, a width of 5 to 30 mm, and a length of 5 to 30 mm. Or it is cut into cubes. As the material of the foamable resin plate 4a, a foamed sheet is formed by including bubbles in a resin such as polypropylene, polyethylene, or polyester, and the specific gravity is adjusted to about 0.1 to 0.5. And the fiber filter medium which comprises the said plate-shaped object is comprised with the thing of three types of different fiber diameters, and the 1st filament 4b is the heat-fusible composite fiber which coat | covered the polypropylene core with polyethylene, and the fineness is 18 ~ 65 denier, the second filament 4c is made of polypropylene fiber and has a fineness of 3 to 10 denier, and the third filament 4d is a heat-fusible composite fiber in which a polypropylene core is coated with polyethylene and has a fineness of 1.5 to 6 A web in which each fiber of denier is mixed is formed into a sheet by a needle punching method and heat-treated without smoothing the web raising state, and has an apparent specific gravity of about 0.9. The fiber filter medium 4 thus molded can be arbitrarily adjusted to have a specific gravity of 0.2 to 0.8 in accordance with the raw water to be treated. Moreover, by using the fiber filter medium 4 having a large porosity, high-concentration raw water such as untreated sewage during rainy weather can be processed at a high speed of 1000 to 2000 m / day.
[0016]
【The invention's effect】
In the high-speed filtration device of the present invention, a high-concentration raw water such as untreated sewage can be treated at high speed by combining a floatable synthetic resin fiber filter medium with a large porosity and a pretreatment device. Furthermore, since low-concentration raw water such as sewage secondary treated water in fine weather can be treated, the discharge load can be reduced and the equipment can be used effectively throughout the year. Further, since the fiber filter medium used in the present invention is formed on the basis of polypropylene fiber, it has high strength, excellent wear resistance, and stable treated water can be obtained over a long period of time. And since this fiber filter medium can perform raw water treatment without chemical injection, no chemical injection equipment is required, running costs and initial costs can be reduced, and maintenance management becomes easy.
[Brief description of the drawings]
FIG. 1 is a flow sheet diagram of a high-speed filtration device according to the present invention.
FIG. 2 is a side sectional view of a high-speed filtration device provided with a pretreatment device by gravity precipitation according to the present invention.
FIG. 3 is a side sectional view of a high-speed filtration device provided with a pretreatment device by rough filtration according to the present invention.
FIG. 4 is a side sectional view of a high-speed filtration device provided with a screen pretreatment device according to the present invention.
FIG. 5 is a longitudinal sectional view of the screen device.
FIG. 6 is a perspective view of a fiber filter medium according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Filtration tank 2 Screen 3 Filter medium layer 4 Fiber filter medium 4a Foamable resin board 4b First filament 4c Second filament 4d Third filament 5 Split plate 6 Pretreatment apparatus 6a Gravity precipitation apparatus 6b Coarse filtration apparatus 6c Screen apparatus 7 Floating hollow Cylindrical filler 8 screen

Claims (5)

Filtration tank in which a filter tank (3) is formed by filling a floatable fiber filter medium (4) in a treatment tank having a filter medium (2) for preventing the loss of the filter medium on the top, and performing an upward flow filtration process. In (1), untreated sewage from the combined sewer system is supplied to the filtration tank (1) via the pretreatment device (6) provided in the previous stage of the filtration tank (1) when it rains, and the pretreatment device ( 6) Directly supplying the secondary treated water to the filtration tank (1) without going through, and suspending a dividing plate (5) made of a perforated plate that equally divides the filtration tank (1) into a plurality of the filtration medium (1) As the fiber filter medium (4) forming the layer (3), the foamable resin plate (4a) is bonded by sandwiching a plurality of synthetic resin fibers having different fiber diameters into a cloth shape , and the specific gravity is 0.2. A high-speed filtration device using a fiber filter material, characterized by using a material that has been adjusted to ˜0.8 and cut. The fiber filter medium (4) is a non-woven fiber filter medium composed of three types of synthetic resin fibers (4b, 4c, 4d) having different fiber diameters, and the first filament (4b) is made of polyethylene at the core of polypropylene. Coated heat-sealable composite fiber with fineness of 18-65 denier, second filament (4c) made of polypropylene fiber with fineness of 3-10 denier, third filament (4d) with polypropylene core made of polyethylene A coated sheet of heat-fusible composite fiber and mixed with each fiber having a fineness of 1.5 to 6 denier is formed into a cloth by a needle punching method, and heat-treated without smoothing the web raised state to form a plate-like body and then, foaming resin plate (4a) was Awa bonded sandwich in plate-like member, a thickness of 3 to 30 mm, width 5 to 30 mm, a length walk straight square 5 to 30 mm Fast filtration apparatus using a fiber filter material according to claim 1, characterized in that cut into cuboid. As the pretreatment device (6) provided in the preceding stage of the filtration tank (1), any one of the gravity precipitation device (6a), the coarse filtration device (6b), and the screen device (6c ) is used as a contaminant. The high-speed filtration apparatus using the fiber filter material according to claim 1, wherein the filtration is performed in the filtration tank (1) after removing water.   Among the pretreatment devices (6), the coarse filtration device (6b) is characterized by using a resin floating hollow cylindrical filler (7) having a diameter of 5 to 20 mmΦ and a length of 10 to 30 mm. A high-speed filtration device using the fiber filter medium according to any one of claims 1 to 3.   Of the pretreatment device (6), the screen device (6c) is provided with a screen (8) provided with a perforated plate having a pore diameter of 1 to 10 mmΦ. A high-speed filtration device using the fiber filter medium according to any one of the above.

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