JP2011115702A - Backwashing method of long fiber filtration apparatus and long fiber filtration apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a backwashing method of a long fiber filtration apparatus and the long fiber filtration apparatus performing efficient backwashing even without running backwashing water at high flow speed. <P>SOLUTION: The backwashing method of a long fiber filtration apparatus is provided in which raw water is passed downward in a filtration tank where long fiber bundles with free upper ends and lower ends fixed to a support set in the filtration tank are erected and filtration treatment is performed. The backwashing method includes: air washing step of washing long fiber bundles by introducing air from a lower part of the filtration tank while water is stored in the filtration tank; discharging step of discharging the water in the filtration tank from the lower part of the filtration tank after the air washing step; and backwashing step of washing the long fiber bundles by passing the backwashing water upward from the lower part of the filtration tank and discharging the backwashing water from an upper part of the filtration tank. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a technique for a long fiber filtration device, and more particularly to a technique for a backwashing method for a long fiber filtration device.

  Conventionally, in various treatment processes such as water treatment facilities, sewage treatment facilities, industrial wastewater treatment facilities, industrial water treatment facilities, etc., long fiber bundles have been used as filter media as filtration treatments for removing suspended matter in raw water. The filtration process used is known.

  For example, in Patent Document 1 and Patent Document 2, a support body is installed inside the filtration tank, and the lower end of the long fiber bundle is fixed to the upper part of the support body, and a filter body having the upper end as a free end is formed. A long-fiber filtration device is described in which raw water is passed in a downward flow from the upper end to the lower end of a long-fiber bundle, and suspended substances in the raw water are captured by voids in the long-fiber bundle. Filtration using a long fiber bundle as a filter medium has less head loss compared to sand filtration and can be filtered at high speed.

  In this long fiber filtration device, if the suspended solids trapped in the long fiber bundles increase with the continuation of the treatment, the filtration capacity decreases. Therefore, in order to recover the filtration capacity, washing water (back washing water) and air are introduced from the lower part of the filtration tank, and back washing is discharged from the upper part of the filtration tank to wash the long fiber bundle. That is, backwashing is performed when a filtration process for a predetermined period is performed or when the head loss is increased.

JP-A-63-315110 Japanese Laid-Open Patent Publication No. 1-304011

  However, in the case of performing a filtration process for a predetermined period or when the head loss increases, backwashing water and air are introduced from the lower part of the filtration tank and discharged from the upper part of the filtration tank. In order to discharge the suspended solids out of the filtration tank, the backwash water must flow at a high speed. And in order to flow backwashing water by high-speed flow, the pump and piping for flowing backwashing water must be enlarged, and there are problems such as increase in equipment size and increase in equipment cost.

  Then, the objective of this invention is providing the backwashing method and the long fiber filtration apparatus of the long fiber filtration apparatus which can perform backwash efficiently, even if it does not flow backwash water by a high-speed flow.

  The present invention is a long fiber filtration in which raw water is passed in a downward flow into a filtration tank in which a long fiber bundle fixed to a support body having an upper end at a free end and a lower end fixed to a support installed in the filtration tank. A backwashing method for an apparatus, in which water is stored in the filtration tank, air is introduced from the lower part of the filtration tank, and the long fiber bundle is washed, and after the air washing process A draining process for draining the water in the filtration tank from the lower part of the filtration tank, and passing backwash water from the lower part of the filtration tank in an upward flow, draining from the upper part of the filtration tank, And a backwashing step for washing the fiber bundle.

  Moreover, in the backwashing method of the said long fiber filtration apparatus, it is preferable to implement in order of the said air washing process, the said discharge process, and the said backwashing process.

  Moreover, in the backwashing method of the said long fiber filtration apparatus, it is preferable to implement the said backwashing process, after repeating the said air washing process and the said discharge process in multiple times.

  Moreover, in the backwashing method of the said long fiber filtration apparatus, it is preferable that the amount of backwashing water of the said backwashing process shall be 3 times or more of the volume of the said long fiber bundle.

  Moreover, in the backwashing method of the said long fiber filtration apparatus, it is preferable that the water in the said filtration tank in the said discharge process and the treated water in the said filtration process are each discharged | emitted from a separate discharge port.

  Further, the present invention is directed to flowing raw water in a downward flow into a filtration tank comprising a support body installed in the filtration tank, and a long fiber bundle having an upper end as a free end and a lower end fixed to the support body. A long fiber filtration device for performing filtration treatment, wherein air is introduced from the lower part of the filtration tank, and the lower discharge port for discharging the water in the filtration tank after washing the long fiber bundle is the filtration In order to backwash the long fiber bundles installed in the lower part of the tank, an upper outlet for discharging the backwash water that has flowed upward from the lower part of the filtration tank is installed in the upper part of the filtration tank. Yes.

  Moreover, the said long fiber filtration apparatus WHEREIN: It is preferable that the said lower discharge port is installed in the said support body.

  Moreover, the said long fiber filtration apparatus WHEREIN: It is preferable that the said lower discharge port is a discharge port different from the discharge port of the treated water in the said filtration process.

  According to the present invention, backwashing can be performed efficiently without flowing backwashing water at a high speed.

It is a schematic diagram which shows an example of a structure of the long fiber filtration apparatus which concerns on embodiment of this invention. It is an upper surface schematic diagram which shows an example of a structure of a support body. It is a figure which shows the relationship between the filtration continuation time of 3rd cycle (filtration-backwashing 3 times), and a loss head.

  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.

  Drawing 1 is a mimetic diagram showing an example of composition of a long fiber filtration device concerning an embodiment of the present invention. 1 includes a filtration tank 10, a raw water inflow pipe 12, a treated water outflow pipe 14, a backwash water inflow pipe 16, a backwash drainage outflow pipe 18, a water collection pipe 20, an air inflow pipe 22, and a raw water storage. A tank 24, a treated water tank 26, a raw water pump 28, a backwash pump 30, and a backwash blower 32 are provided.

  A support 34 is installed in the filtration tank 10. FIG. 2 is a schematic top view illustrating an example of the configuration of the support. The support 34 includes a support plate 36 in which a plurality of openings are formed, and a support nozzle 38 (strainer) fitted in each of the openings. The lower end of the long fiber bundle 40 is fixed to the support nozzle 38, and the upper end of the long fiber bundle 40 is a free end. That is, the long fiber bundle 40 is fixed to the support 34. The support plate 36 is formed with a plurality of small holes different from the plurality of openings, and the small holes serve as the lower discharge port 42.

  However, the support 34 used in the present embodiment is not limited to the above configuration as long as it supports the long fiber bundle 40. Steel wool or the like that fixes the lower end of the long fiber bundle 40, steel wool, or the like. It may be composed of a support plate 36 or the like for fixing. The support plate 36 is provided with a lower discharge port 42 and a discharge port through which treated water passes.

  Raw water is stored in the raw water storage tank 24. One end of the raw water inflow pipe 12 is connected to the raw water storage tank 24, and the other end is connected to the upper part of the filtration tank 10 via the raw water pump 28 and the valve 44. In addition, when raw | natural water can flow into the filtration tank 10 by natural flow, the raw | natural water pump 28 is unnecessary. As described above, the filtration tank 10 is filled with a large number of long fiber bundles 40 each having a lower end fixed to a support body 34 (substantially a support nozzle 38) provided in the lower part. One end of the treated water discharge pipe is connected below the support 34 of the filtration tank 10, and the other end is connected to the treated water tank 26 via a valve 46. Further, one end of the backwash water inflow pipe 16 is connected to the treated water tank 26, and the other end is connected to the lower side of the support body 34 of the filtration tank 10 via the backwash pump 30 and the valve 48. Further, one end of the air inflow pipe 22 is connected to the lower side of the support 34 of the filtration tank 10, and the other end is connected to the backwash blower 32 through the valve 50. A backwash drainage pipe 18 provided with a valve 56 is connected to the upper side surface of the filtration tank 10. Further, one end of the water collecting pipe 20 is connected to the lower discharge port 42 described above, and the other end is connected to the backwash drainage outflow pipe 18 via a valve 54.

  Next, the operation (filtration and backwashing method) of the long fiber filtration device 1 according to this embodiment will be described.

  Raw water containing suspended substances such as industrial water, secondary sewage water, tertiary sewage water, river water, lake water, coagulated sediment supernatant water, various process intermediate waters, various recovered waters, various waste waters, etc. After being stored in the storage tank 24, the raw water pump 28 passes through the raw water inflow pipe 12 and is introduced into the filtration tank 10. The raw water introduced from above the filtration tank 10 passes downward from the upper part of the filtration tank 10, that is, toward the long fiber bundle 40, and the suspended matter is suspended by the voids of the long fiber bundle 40. The treated water that has been captured and clarified passes through the support nozzle 38 and is sent to the treated water outflow pipe 14. Then, the treated water passes through the treated water discharge pipe and is stored in the treated water tank 26. During the filtration process, the valves 44 and 46 are opened, and the valves 48, 50, 54 and 56 are closed. The treated water is then subjected to sterilization treatment or the like.

  In this embodiment, when the filtration process for a predetermined period is performed, or when the loss head in the filtration tank 10 rises to a predetermined height, the backwash process is performed, and the long fiber bundle 40 is washed.

<Air cleaning process>
Specifically, the valves 44 and 46 are closed, the raw water flow is stopped and water is accumulated in the filtration tank 10, the valve 50 is opened, and the compressed air is blown by the blower through the air inflow pipe 22. Is introduced from the lower part of the filtration tank 10, passes through the support nozzle 38, and is supplied to the upper part of the filtration tank 10. In this way, the water inside the filtration tank 10 is agitated by the inflow of compressed air, and the long fiber bundle 40 vibrates and expands, whereby the suspension trapped in the voids and the surface of the long fiber bundle 40 and the like. The material is peeled off. In addition, after draining the raw water in the filtration tank 10, the valves 48 and 50 are opened, and the backwash water is caused to flow into the filtration tank 10 through the backwash water inflow pipe 16 by the backwash pump 30. Compressed air may be introduced into the filtration tank 10 while water is accumulated, or compressed air is introduced into the filtration tank 10 while allowing the backwash water to flow into the filtration tank 10 through the backwash water inflow pipe 16. May be.

<Discharge process>
After the operation of the backwash pump 30 is stopped and the valves 48 and 50 are closed, the valve 54 is opened and the suspended matter separated by the water and air backwash in the filtration tank 10 is removed from the lower discharge port 42. To discharge from. The water and suspended matter discharged from the lower discharge port 42 are discharged from the backwash drainage outflow pipe 18 through the water collection pipe 20 to the outside of the long fiber filtration device 1. By this discharge process, most of the suspended solids (particularly heavy suspended solids) are discharged out of the long fiber filtration device 1 through the lower discharge port 42. As a result, since the suspended solids in the filtration tank 10 are very small (especially suspended solids with a low specific gravity), it is not necessary to flow backwash water at a high speed in the backwashing process described later, and used in the backwashing process. Thus, the capacity of the backwash pump 30, the diameter of the backwash water inflow pipe 16 and the backwash drainage outflow pipe 18 can be reduced.

  The lower outlet 42 in the present embodiment is installed at the lower part of the filtration tank 10. Here, in this specification, the bottom from the filtration tank 10 to the height of the upper end of the long fiber bundle 40 is referred to as the lower part of the filtration tank 10. The upper part of the filtration tank 10 is referred to as the upper part of the filtration tank 10. That is, the lower discharge port 42 may be installed at any position as long as it is the lower part of the filtration tank 10, but in order to efficiently discharge suspended substances separated by back air washing, It is preferable to install on the side surface of the filtration tank 10. When installing the lower discharge port 42 on the side surface of the filtration tank 10 near the support 34, it is desirable to install it on the side of the filtration tank 10 up to 20 cm above the support 34, and up to 10 cm above the support 34. It is more desirable to install on the side surface of the filtration tank 10. Moreover, in order to discharge | emit the suspended solid peeled off by air backwashing more efficiently, providing in the support body 34 like this embodiment is more preferable.

  The outlet of the filtration tank 10 to which one end of the treated water discharge pipe 46 is connected may be the lower outlet 42. In this case, the treated water discharge pipe 46 is branched, and one is connected to the treated water tank 26 and the other is connected to the backwash drainage outflow pipe 18. However, if the lower discharge port 42 is made the same as the treated water discharge port in this way, the suspended matter is trapped by the long fibers in the discharge process and cannot be discharged efficiently. It is preferable to install the discharge port 42 and the treated water discharge port separately.

<Backwash process>
In the backwashing process, the valve 54 is closed, the valves 48 and 56 are opened, and the backwash water is caused to flow into the filter tank 10 through the backwash water inflow pipe 16 by the backwash pump 30. Then, the backwash water is passed upward from the lower portion of the filtration tank 10 through the support nozzle 38 and discharged from the backwash drainage pipe 18 to the outside of the long fiber filtration device 1.

  The amount of backwash water in the backwashing step is not particularly limited, but the (effective) volume of the long fiber bundle 40 is that the suspended matter in the filtration tank 10 can be efficiently removed. It is preferable that the amount is 3 times or more.

  Wastewater discharged from the backwash drainage pipe 18 is transferred to a wastewater treatment facility. In addition, it is preferable to use the treated water etc. which are stored in the treated water tank 26 as backwash water.

  In the present embodiment, as described above, the backwashing step is preferably performed after the air washing step and the discharging step, that is, the backwashing step is preferably performed at the end, and the air washing step and the discharging step are repeated a plurality of times. It is more preferable to perform a backwashing process later. However, in the backwashing method of this embodiment, it is not restricted to what was demonstrated above, For example, you may perform an air washing process and a discharge process after a backwashing process. Further, the backwashing step and the air washing step may be performed simultaneously, and then the discharge step may be performed (preferably, the backwashing step is performed thereafter).

  As the material of the long fiber constituting the long fiber bundle 40, synthetic fibers such as acrylic, polyester, polypropylene, polyamide, polyacrylamide, and Kevlar, natural fibers such as cotton and wool, synthetic fibers thereof, and the like Is mentioned. Synthetic fibers are preferred from the standpoint of high strength, etc., and polyester-based synthetic fibers that have good processability are preferred.

  The length of the long fiber bundle 40 is not particularly limited as long as it is determined according to the height of the filtration tank 10 to be used, but is preferably 500 mm or more and less than 3000 mm, and is 1000 mm or more and less than 1500 mm. Is more preferable. When the length of the long fiber bundle 40 is less than 500 mm, the processing efficiency may decrease because the effective volume of the filter medium is small. When the length is 3000 mm or more, the bending of the long fiber bundle 40 increases and the uprightness decreases. For this reason, the aggregate density of the long fiber bundles 40 is increased, and the effective volume may be reduced to lower the processing efficiency. In addition, the length of the long fiber bundle 40 is the length from the upper end to the lower end of the long fiber bundle 40 in a state in which the long fiber bundle 40 is almost upright in water in a state where no water is passed when the filtration tank 10 is filled. That's it.

The filling density of the long fiber bundle 40 is not particularly limited as long as it is determined according to the flow rate of raw water, but is preferably 15 kg or more and less than 200 kg per 1 m ² of the cross-sectional area of the filtration tank 10. More preferably, it is 30 kg or more and less than 100 kg per 1 m ² of the cross-sectional area of the tank 10. When the packing density of the long fiber bundle 40 is less than 15 kg per 1 m ² of the cross-sectional area of the filtration tank 10, the pressure loss becomes small, but the effective volume of the long fiber bundle 40 is small, and thus the filtration efficiency may decrease. If it is as described above, the aggregate density of the long fiber bundle 40 is increased, the effective volume is decreased, and the filtration efficiency may be decreased, or the pressure loss may be increased. The filling density of the long fiber bundle 40 is obtained from the dry weight of the long fiber bundle 40 and the cross-sectional area of the filtration tank 10 filled with the long fiber bundle 40.

  In the long fiber filtration device 1 according to the present embodiment, the filtration rate can be 1000 m / day or more, preferably 1200 m / day or more, more preferably 1500 m / day or more.

  The long fiber filtration device 1 according to the present embodiment is used in various treatment processes such as a water treatment facility, a sewage treatment facility, an industrial wastewater treatment facility, and an industrial water treatment facility. It can be used for the treatment of secondary treated water, river water, lake water, coagulated sediment supernatant water, various process intermediate water, various recovered water, various waste water, and the like.

  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.

  In Example 1, the test was conducted under the following conditions using the long fiber filtration device shown in FIG. Well water Kanto Loam (JIS test powder 1-7 type) added to about 100 mg / L is used as raw water, and polyaluminum chloride (flocculating agent) 14 mg / L is added to the raw water. Water was passed through (φ280 mm × 2000 mm) at a filtration rate (LV) of 1000 m / day. The height of the fiber bundle installed in the filtration tank was 1 m from the support. The lower outlet was installed on the support. In the backwash, when the head loss reaches 1000 mm, the air washing step and the discharging step are performed three times, and then the backwashing step is performed with 180 L of backwashing water corresponding to three times the volume of the long fiber bundle. Carried out. The flow rate (LV) of backwash water was 45 m / h, the flow rate (LV) of backwash air was 150 m / h, and the amount of wash water (total) was 510 L.

  In Example 2, the test was performed under the same conditions as in Example 1 except that the lower discharge port was provided on the side surface of the filter tank (about 10 cm above the support).

  In Example 3, the test was performed under the same conditions as in Example 1 except that the air washing step and the discharge step were each performed once.

  In Example 4, the backwashing process was performed with 60 L of backwashing water corresponding to the amount of water that was one time the volume of the long fiber bundle, and the amount of washing water (total) was 390 L. The test was conducted under conditions.

  In the comparative example, backwashing water and air were introduced from the lower part of the filtration tank, and backwashing was performed by a method of discharging from the upper part of the filtration tank (the discharge process was not performed). The total amount of washing water was 510 L as in Example 1.

  Table 1 summarizes the results of the SS trapping amount by filtration treatment of Examples 1 to 4 and the comparative example, the SS discharge amount by backwashing, the SS accumulation amount in the filtration tank after backwashing, and the filtration duration time. Each data in Table 1 is an average value of three tests. Here, the amount of SS captured was determined by filtration duration x raw water inflow rate x raw water SS concentration x SS removal rate. Moreover, SS discharge | emission amount was calculated | required by the SS density | concentration in backwashing water amount x backwashing drainage. The SS accumulation amount was the difference between the SS trapping amount and the SS discharge amount.

  FIG. 3 is a diagram showing the relationship between the filtration continuation time and the loss head in the third cycle (filtration-backwashing three times).

  As can be seen from Table 1 and FIG. 3, it was confirmed that Examples 1 to 4 had higher SS discharge amount, lower SS accumulation amount, and longer filtration duration than Comparative Example. As can be seen from the comparison between Example 1 and Example 2, when the lower discharge port was provided on the support, the SS discharge amount was higher, the SS accumulation amount was lower, and the filtration duration time was longer. In addition, as can be seen from the comparison between Example 1 and Example 3, the amount of SS discharged is higher when the air cleaning step and the discharging step are performed three times, and when the lower discharge port is provided on the support, the SS discharge amount is higher. The accumulated amount was low, and the filtration duration was longer. Furthermore, as can be seen from the comparison between Example 1 and Example 4, the case where the backwashing process was performed with the amount of water three times the volume of the long fiber bundle was the case where the lower outlet was provided on the support. The discharge amount was high, the SS accumulation amount was low, and the filtration duration was longer.

  DESCRIPTION OF SYMBOLS 1 Long fiber filtration apparatus, 10 Filtration tank, 12 Raw water inflow pipe, 14 Treated water outflow pipe, 16 Backwash water inflow pipe, 18 Backwash drainage outflow pipe, 20 Water collection pipe, 22 Air inflow pipe, 24 Raw water storage tank, 26 Treatment Water tank, 28 Raw water pump, 30 Backwash pump, 32 Backwash blower, 34 Support body, 36 Support plate, 38 Support nozzle, 40 Long fiber bundle, 42 Lower discharge port, 44, 46, 48, 50, 54, 56 Valve .

Claims (8)

Backwashing of a long fiber filtration device in which raw water is passed in a downward flow through a filtration tank in which a long fiber bundle fixed to a support body with the upper end being a free end and fixed at a lower end is mounted on a support body. A method,
In a state where water is stored in the filtration tank, air is introduced from the lower part of the filtration tank, and the long fiber bundle is washed, and
After the air washing step, the draining process of draining the water in the filtration tank from the lower part of the filtration tank, and passing backwash water upward from the lower part of the filtration tank and discharging from the upper part of the filtration tank And the backwashing process which wash | cleans the said long fiber bundle, The backwashing method of the long fiber filtration apparatus characterized by the above-mentioned.   It is a backwashing method of the long fiber filtration apparatus of Claim 1, Comprising: It implements in order of the said air washing process, the said discharge process, and the said backwashing process, The backwashing method of the long fiber filtration apparatus characterized by the above-mentioned.   The backwashing method for a long fiber filtration device according to claim 1, wherein the backwashing step is carried out after repeating the air washing step and the discharge step a plurality of times. Method.   It is a backwashing method of the long fiber filtration apparatus of any one of Claims 1-3, Comprising: The amount of backwashing water of the said backwashing process shall be 3 times or more of the volume of the said long fiber bundle. A method for backwashing a long fiber filtration device.   It is the backwashing method of the long fiber filtration apparatus of any one of Claims 1-4, Comprising: The water in the said filtration tank in the said discharge process and the treated water in the said filtration process are respectively separate discharge ports A method for backwashing a long fiber filtration device, characterized by being discharged from Filtration treatment is performed by passing raw water in a downward flow into a filtration tank provided with a support body installed in the filtration tank, and a long fiber bundle whose upper end is a free end and whose lower end is fixed to the support body. A long fiber filtration device,
Air is introduced from the lower part of the filtration tank, and a lower outlet for discharging the water in the filtration tank after washing the long fiber bundle is installed at the lower part of the filtration tank,
In order to backwash the long fiber bundle, an upper discharge port for discharging backwash water that has flowed in an upward flow from the lower part of the filtration tank is installed at the upper part of the filtration tank. Fiber filtration device.   It is a long fiber filtration apparatus of Claim 6, Comprising: The said lower discharge port is installed in the said support body, The long fiber filtration apparatus characterized by the above-mentioned.   It is a long fiber filtration apparatus of Claim 6, Comprising: The said lower discharge port is a discharge port different from the discharge port of the treated water in the said filtration process, The long fiber filtration device characterized by the above-mentioned.

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