JP4532297B2 - Filtration apparatus and filtration method - Google Patents

Description

  The present invention relates to a filtration device and a filtration method for removing suspensions in raw water such as sewage secondary treated water and sewage tertiary treated water.

  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, Patent Document 1 and Patent Document 2 include a filter body in which a support body is horizontally installed or filled in the filtration device, the lower end of the long fiber bundle is fixed to the upper part of the support body, and the upper end is a free end. Is formed, the raw water is passed in a downward flow from the upper end to the lower end of the long fiber bundle, and the suspension in the raw water is captured by the voids in the long fiber bundle. The filtration process using a long fiber bundle as a filter medium has less head loss than sand filtration, and can be filtered at a high flow rate. In addition, since the lower end of the long fiber bundle is fixed to the support, high-flow backwash water can be introduced, and the suspended matter captured by the long fiber bundle can be removed by a short backwash. be able to. Filtration using such a long fiber bundle as a filter medium is performed in tertiary treatment of sewage.

  Patent Document 3 describes a sewage treatment contact material in which a crimped fiber assembly in which upper and lower ends are bound is housed inside a shape-retaining mesh container.

JP-A-63-315110 Japanese Laid-Open Patent Publication No. 1-304011 Japanese Utility Model Publication No. 7-21196

  However, in the filtration devices described in Patent Document 1 and Patent Document 2, the filtration speed capable of stable filtration with a low loss head is 800 m / day or less, and when the filtration speed is high, the loss head tends to increase. Filtration duration is reduced. The reason for the decrease in the filtration duration is that when the filtration speed is high, the aggregate density of the filter medium of the long fiber bundle at the time of passing water is large. For example, the filter medium is consolidated by about 500 mm per 1000 mm filling length, and the effective volume of the filter medium is reduced. It is thought to do.

  Patent document 3 uses a crimped fiber assembly as a sewage treatment contact material for supporting microorganisms, and the upper and lower ends of the contact material are bound to perform physical filtration. There is no.

  The present invention is a filtration device and a filtration method that can be operated at a fast filtration rate and can increase the filtration duration in a filtration treatment in which a suspension in raw water is removed by a long fiber bundle.

The present invention is a filtration device for capturing a suspension in raw water with a long fiber bundle, a filtration tower, a support horizontally or packed inside the filtration tower, and a lower end fixed to the support. Rutotomoni has a long fiber bundles in which the upper end as a free end, the long fibers constituting the long fiber bundle has been crimped, number of crimps Ri der 9 / 25mm or more, the material of the long fibers Ru polyester der.

  Moreover, the said filtration apparatus WHEREIN: It is preferable that the thickness of the said long fiber is 20 micrometers or more and less than 80 micrometers.

  Moreover, the said filtration apparatus WHEREIN: It is preferable that the speed of the said filtration is 1000 m / day or more.

Further, the present invention is a filtration method for capturing a suspension in raw water with a long fiber bundle, the lower end of the long fiber bundle is fixed to a support, the upper end is a free end, and the long fiber bundle filtration by passed through the raw water in the downflow in the long long fibers forming the fiber bundle has been crimped, number of crimps Ri der 9 / 25mm or more, the length the material of the fiber is Ru polyester der.

  Moreover, in the said filtration method, it is preferable that the thickness of the said long fiber is 20 micrometers or more and less than 80 micrometers.

  Moreover, in the said filtration method, it is preferable that the speed of the said filtration is 1000 m / day or more.

  According to the present invention, in the filtration process for removing the suspension in the raw water by the long fiber bundle, the lower end is fixed to the support and the long fiber constituting the long fiber bundle having the upper end as a free end is crimped. By applying and setting the number of crimps to 7 pieces / 25 mm or more, it is possible to operate at a high filtration rate and increase the filtration duration.

  Hereinafter, embodiments of the present invention will be described.

  An example of a filtration device according to an embodiment of the present invention is shown in FIG. The filtration device 1 according to this embodiment includes a filtration tower 10, a support 12, and a long fiber bundle 14.

  In the filtration device 1, a support body 12 is provided horizontally inside the filtration tower 10, and the lower end of one or a plurality of long fiber bundles 14 is fixed to the support body 12. The upper end of the long fiber bundle 14 is a free end. In FIG. 1, it is described that the long fiber bundles 14 are sparsely installed in the filtration tower 10, but actually, the long fiber bundles 14 are filled so as to fill the filtration tower 10.

  Moreover, an example of the water treatment apparatus containing the filtration apparatus 1 which concerns on this embodiment is shown in FIG. 2, and the structure is demonstrated. The water treatment device 3 includes a filtration device 1, a raw water inflow pipe 16, a treated water outflow pipe 18, a backwash water inflow pipe 20, a backwash drainage outflow pipe 22, an air inflow pipe 24, a raw water storage tank 26, and a treated water tank 28.

  Raw water is stored in the raw water storage tank 26. One end of the raw water inflow pipe 16 is connected to the raw water storage tank 26, and the other end is connected to the upper part of the filtration tower 10 via the raw water pump 42 and the valve 32. In addition, the raw water pump 42 is unnecessary when it can flow in under natural flow. As described above, the filtration tower 10 is filled with a number of long fiber bundles 14 whose lower ends are fixed to the support 12 provided at the lower portion. One end of the treated water outflow pipe 18 is connected to the lower side of the support 12 of the filtration tower 10, and the other end is connected to the treated water tank 28 through a valve 34. One end of the backwash water inflow pipe 20 is connected to the treated water tank 28, and the other end is connected below the support 12 of the filtration tower 10 via the backwash pump 44 and the valve 36. One end of an air inflow pipe 24 is also connected to the lower side of the support 12 of the filtration tower 10, and the other end is connected to the blower 30 via a valve 40. Further, a backwash drainage pipe 22 provided with a valve 38 is connected to the upper end of the filtration tower 10.

  Next, operation | movement of the water treatment apparatus 3 containing the filtration apparatus 1 which concerns on this embodiment is demonstrated. Raw water including suspensions such as waterworks water, secondary treated water, tertiary treated water, river water, lake water, coagulation sediment supernatant water, various process intermediate water, various recovered water, various waste water, After being retained in the raw water storage tank 26, the raw water pump 42 or the like passes through the raw water inflow pipe 16 and is introduced into the filtration tower 10 of the filtration device 1. Initially, the long fiber bundle 14 that has been almost upright in the water is bent by its own weight and the flow of raw water, and its height is reduced. The raw water that has flowed in from above the filtration tower 10 passes from the upper part to the lower part of the filtration tower 10, that is, in a downward flow toward the long fiber bundle 14, and the suspended matter is formed by the voids of the long fiber bundle 14. Captured and clarified treated water flows out from the lower part of the filtration tower 10 and flows into the treated water tank 28 through the treated water outflow pipe 18. At this time, the valves 32 and 34 are opened, and the valves 36, 38, and 40 are closed. Thereafter, the treated water is subjected to a disinfection treatment or the like.

  In the flow of raw water, the long fiber bundle 14 is contracted in the height direction as described above, but the lower part is more bent than the upper part of the long fiber bundle 14, so the lower part As a result, the long fiber bundle 14 is densely packed, and as a result, the suspension in the raw water is effectively trapped in the voids, the surface and the like of the entire long fiber bundle 14 in the height direction. However, when the long fiber bundles 14 are totally sunk and consolidated inside the filtration tower 10 and the aggregate density of the long fiber bundles 14 becomes too high, filtration is almost performed at the upper part of the long fiber bundles 14 in the raw water. The effective volume for suspension capture is reduced, reducing the amount of suspension that can be captured and reducing the efficiency of filtration. Therefore, in order to improve the filtration efficiency, the long fibers constituting the long fiber bundle 14 are required to have a firm strength that maintains a certain degree of uprightness with respect to the downward water flow.

  Therefore, in the present embodiment, the long fibers constituting the long fiber bundle 14 are crimped, and the number of crimps is defined to be a specific number or more. That is, the long fibers constituting the long fiber bundle 14 are crimped, and the number of crimps is 7 pieces / 25 mm or more. Here, “crimping” means “crimping of fibers” as described in JIS L0208. The “crimp number” means “the number of crimps per unit length of fiber” as described in JIS L0208, and the crimp number is a method described in JIS L1015. According to the above, “the number of crimps per 25 mm length of the long fiber” is obtained.

  By applying a crimping process to the long fibers constituting the long fiber bundle 14, it is possible to maintain a certain degree of uprightness with respect to the water flow in the downward flow, and to reduce the effective volume for capturing the suspension in the raw water. Can be suppressed. Moreover, by performing the crimping process, the voids due to the entanglement of the fibers increase, and the suspension in the raw water can be captured more effectively.

  In this embodiment, the number of crimps of the long fibers is 7/25 mm or more, preferably 8/25 mm or more, and more preferably 9/25 mm or more. When the number of crimps is less than 7 pieces / 25 mm, the long fiber bundle 14 becomes weak and cannot maintain uprightness with respect to the downward flow of the raw water. The effective volume for capture is reduced and the filtration efficiency is reduced. A larger number of crimps is preferable because the uprightness of the long fiber bundle 14 is improved and the effective volume is increased, and the suspension in the raw water can be captured more effectively. In order to perform crimping, the upper limit is about 25 pieces / 25 mm.

  The thickness of the long fiber is not particularly limited as long as it is determined so as to satisfy the uprightness of the long fiber bundle 14 and the uniformity of crimp, but is preferably 20 μm or more and less than 80 μm, preferably 30 μm or more and less than 50 μm. It is more preferable that When the length of the long fiber is less than 20 μm, the long fiber bundle 14 is bent and the uprightness is lowered, so that the assembly density of the long fiber bundle 14 is increased, the effective volume is reduced, and the processing efficiency is lowered. In some cases, if it is 80 μm or more, it may be difficult to uniformly crimp the number of crimps to 7 pieces / 25 mm or more.

In addition, the thickness of the long fiber is obtained by converting into the fiber thickness (μm) from the fineness (denier) of the fiber (JIS L0208) and the specific gravity of the fiber. For example, in the case of a fiber with 2 denier (2 × 9,000 m / g) and a specific gravity of 1.3, the length per cm ³ is
[2 × 9,000 (m / g) × 100] /1.3=1,384,620 cm / cm ³
From this, the cross-sectional area A of the fiber is
A (cm) ² = 1/1, 384, 620
It becomes. Since the thickness R (diameter: cm) of the fiber is A = (R / 2) ² × π,
R = [(1 / 1,384,620) × 4 / π] ^1/2
= 0.00096 cm → 9.6 μm
It becomes.

  The length of the long fiber bundle 14 is not particularly limited as long as it is determined according to the height of the filtration tower 10 to be used, but is preferably 500 mm or more and less than 3000 mm, and more preferably 1000 mm or more and less than 1500 mm. . When the length of the long fiber bundle 14 is less than 500 mm, the effective efficiency of the filter medium is small, so that the processing efficiency may be lowered. When the length is 3000 mm or more, the bending of the long fiber bundle 14 becomes large and the uprightness is lowered. For this reason, the aggregate density of the long fiber bundles 14 is increased, and the effective volume may be reduced to lower the processing efficiency. The length of the long fiber bundle 14 is from the upper end to the lower end (upper part of the support 12) of the long fiber bundle 14 in a state of being almost upright in the water in a state where there is no water flow when the filtration tower 10 is filled. Length.

  Here, as an index representing the uprightness of the long fiber bundle 14, the upper end to the lower end (the support 12) of the compacted long fiber bundle 14 in the water flow with respect to the length 1000 mm of the long fiber bundle 14 in the water before the water flow. The consolidation length (mm) up to (upper part) can be used. In order to ensure the effective volume of the filter medium, the consolidation length is preferably 200 mm to 900 mm, and more preferably 300 mm to 600 mm.

  The material of the long fiber constituting the long fiber bundle 14 includes synthetic fibers such as acrylic, polyester, polypropylene, polyamide, polyacrylamide, and kevlar; natural fibers such as cotton and wool, and a mixture thereof. It may be a fiber. Synthetic fibers are preferred from the standpoint of high strength, etc., and polyester-based synthetic fibers that are said to have good processability are preferred. In particular, polyester fibers having a crimp number of 8 or more are more preferable because the uprightness of the long fiber bundle 14 is high and filtration efficiency is high, and polyester fibers having a crimp number of 9 or more are more preferable.

The packing density of the long fiber bundle 14 is not particularly limited as long as it is determined according to the flow rate of raw water and the like, but is preferably 15 kg or more and less than 200 kg per 1 m ^{2 of} the filter cross-sectional area, and the cross-sectional area of the filter is 1 m ^2. More preferably, it is 30 kg or more and less than 100 kg. When the packing density of the long fiber bundle 14 is less than 15 kg per 1 m ^{2 of the} cross-sectional area of the filter, the pressure loss becomes small, but the effective volume of the long fiber bundle 14 is small, so the filtration efficiency may decrease. In some cases, the aggregate density of the long fiber bundles 14 becomes high, the effective volume decreases, and the filtration efficiency decreases, or the pressure loss increases. The packing density of the long fiber bundle 14 is determined from the dry weight of the long fiber bundle 14 and the cross-sectional area of the filtration tower 10 packed with the long fiber bundle 14.

  Moreover, by using the filtration apparatus 1 which concerns on this embodiment, a filtration rate can be 1000 m / day or more, Preferably it is 1200 m / day or more, More preferably, it can be 1500 m / day or more. The long fibers constituting the long fiber bundle 14 are crimped and the number of crimps is set to 7 pieces / 25 mm or more, so that the uprightness of the long fiber bundle 14 is improved, and for a high filtration rate of 1000 m / day or more. However, since the rise of the loss head is suppressed more than before and the filtration continuation time is improved, the filtration rate can be made faster than the conventional 800 m / day.

In this embodiment, in particular, as the long fiber bundle 14, a polyester fiber having a crimp number of 8 pieces / 25 mm or more, a thickness of 30 μm or more and less than 50 μm, and a length of 1000 mm or more and less than 1500 mm is used. The filtration process can be performed in an optimum state by setting the pressure to 15 kg or more and less than 200 kg per 1 m ^{2 of the} cross-sectional area of the filter.

  The support 12 is not particularly limited as long as it supports the long fiber bundle 14, but, for example, a perforated plate or the like is provided inside the lower portion of the filtration tower 10, and the lower end of the long fiber bundle 14 is disposed on the perforated plate or the like. May be fixed, or steel wool or the like may be filled inside the filtration tower 10 and the lower end of the long fiber bundle 14 may be fixed to the steel wool or the like. In addition, when using steel wool, the screen which fixes and supports steel wool is installed in the lower part of steel wool. Further, as the other support 12, a porous laminate such as sintered metal or ceramic may be used.

  When steel wool or a porous laminate is used as the support 12, the fine suspension in the raw water that passes through the long fiber bundle 14 during the passage of water is captured by the steel wool or the porous laminate. Therefore, the quality of treated water can be further improved.

  In the present embodiment, when the suspension in the raw water is fine particles, for example, when the average particle diameter of the suspension is less than 10 μm, before passing through the filtration device 1, for example, the raw water storage tank 26 or in a treatment tank (not shown) provided between the raw water storage tank 26 and the filtration device 1 or the like, an inorganic flocculant such as an aluminum salt or an iron salt, or a cationic, anionic or nonionic polymer. A flocculant or the like may be added. Specifically, polyaluminum chloride flocculant (PAC), iron-silica inorganic polymer flocculant (PSI) combining iron and polymerized silicic acid (silica) which is an inorganic anionic polymer, polyferric sulfate (poly Iron) and the like.

  As the raw water continues to flow, suspensions or aggregates of suspensions are trapped in the voids of the long fiber bundle 14 and the pressure loss gradually increases. When the pressure loss becomes a preset value or when the quality of the treated water is lower than the preset value, the flow of raw water is stopped and the long fiber bundle 14 is washed with backwash water.

  That is, the valves 32, 34, and 36 are closed, the valves 38 and 40 are opened, and compressed air is introduced from the lower part of the filtration tower 10 through the air inlet pipe 24 by the blower 30. The water inside the filtration tower 10 is agitated by the inflow of compressed air, and the long fiber bundle 14 vibrates and expands, whereby suspensions or suspensions trapped in the voids and the surface of the long fiber bundle 14 and the like. The turbid aggregates are peeled off. At this time, the valve 36 is opened with the inflow of compressed air, or the valve 36 is opened after the valve 40 is closed to stop the compressed air, and the backwash water inflow pipe is returned from the lower part of the filtration tower 10 by the backwash pump 44. Backwash water may flow through 20. The backwash water flows out through the backwash drainage outflow pipe 22 and is transferred to a wastewater treatment facility or the like. In addition, it is preferable to use the treated water staying in the treated water tank 28 as the backwash water.

  In this embodiment, in the water treatment in which the suspension in the raw water is removed by the long fiber bundle, the long fibers constituting the long fiber bundle are crimped and the number of crimps is set to 7 pieces / 25 mm or more. Since the uprightness of the long fiber bundle is improved and the effective volume is improved, it is possible to provide a filtration device that can be operated at a high filtration rate and can increase the filtration duration time. Moreover, since the upper end of the contact material is a free end, the trapped suspended matter or the like can be easily removed by washing the contact material by backwashing.

  The filtration device and the filtration method according to the present embodiment are 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. 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 wastewater, etc., especially suitable for the post-process of biological treatment and coagulation sedimentation treatment Can be used. Usable raw water SS (amount of suspended solids) can be suitably used for raw water having a water quality of 10 or more, preferably 10-20.

  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.

(Ratio Comparative Examples)
As Comparative Example 2 , a long fiber bundle of acrylic fibers having a crimp number of 7/25 mm and a fiber thickness of 43 μm. Further, as Comparative Example 1 , a long fiber bundle of acrylic fibers having a crimp number of 5/25 mm and a fiber thickness of 43 μm. Used and filtered. Table 1 shows the fiber material conditions. Moreover, the water treatment apparatus used for experiment is shown in FIG. A perforated plate is used as a support for a filtration tower having an inner diameter of 280 mm and a height of 4000 mm, and the long fiber bundle of Comparative Example 1 is used on one side, and the long fiber bundle of Comparative Example 2 is used on the other side. Each was filled at 1000 mm. The raw water was river water (SS = 17.8 mg / L) and two towers were passed simultaneously, and the filtration rate was LV = 1200 m / day. Loss head measurement and SS measurement of raw water and treated water were performed every hour. When the loss head reached 1000 mm, the long fiber bundle was washed by allowing the treated water and air to pass through the column in an upward flow.

(Example 1 and comparative example)
As Example 1 , a filtration treatment was performed in the same manner as in the comparative example , except that a polyester fiber long fiber bundle having 9 crimps / 25 mm and a fiber thickness of 39 μm was used. The raw water was river water (SS = 19.7 mg / L) and two towers were passed simultaneously, and the filtration rate was LV = 1200 m / day.

(Example 2 and comparative example)
As Example 2 , a filtration treatment was performed in the same manner as in the comparative example , except that a polyester fiber long fiber bundle having 9 crimps / 25 mm and a fiber thickness of 43 μm was used. The raw water was river water (SS = 18.7 mg / L), and two towers were passed simultaneously, and the filtration rate was LV = 1200 m / day.

The results of Example 1, 2 and Comparative Examples 1 and 2 shown in Table 1. Here, the result of Comparative Example 1 was an average value of the results of Comparative Examples 1 (Example 3 in total) in Examples 1 and 2 and Comparative Example 2 . Moreover, the time-dependent change of the loss head with respect to water flow time is shown in FIG. Here, the time when the loss head reached 1000 mm was defined as the filtration duration time. Since the filtration continuation time was significantly different between Comparative Example 1 and Comparative Example 2 , it was shown that there was a large difference in filtration efficiency depending on the number of crimps even with the same material. In Examples 1 and 2 where the number of crimps is further increased, the filtration duration time further increased. FIG. 5 shows a result of comparing the consolidated length obtained from the height of the filled fiber for each SS trapping amount. Despite the large amount of SS trapped, in Examples 1 and 2 , the consolidated length was short. It is considered that the effective volume of the filter medium (long fiber bundle) was not lost because the fibers were not consolidated, and the filtration duration was increased. Moreover, since SS of an Example was lower than the comparative example about the quality of the treated water, it was confirmed that an Example can be applied as a filter medium.

Using the polyester fiber long fiber bundle of Example 1 that was found to be suitable as a filter material in the above experiment, an experiment was performed to determine the optimum range of the filtration rate. Both columns of the water treatment apparatus used in Comparative Example 2 are filled with the polyester fiber long fiber bundle used in Example 1 , and the filtration rate is changed to 1200, 1500, 2000, 2250 m / day, and raw water is passed. I let you. The results are shown in FIG.

  As shown in FIG. 6, when the filtration rate was 1200 to 1500 m / day, the filtration duration was about the same. At a filtration rate of 2000, 2250 m / day, the initial loss head was high and the filtration duration was relatively low, but this is sufficient for operation. However, if the filtration continuation time is about 5 hr, it may not be possible to cope with fluctuations in the quality of the raw water and the amount of water, so the optimal filtration rate range can be said to be 2000 m / day or less.

  Thus, by using a long fiber bundle of fibers having a crimp number of 7 or more as a filter medium, the filtration duration time is significantly increased, and the raw water with SS of about 20 mg / L is used at a filtration rate of 1000 m / day or more. Driving is now possible.

It is a figure which shows the structure of an example of the filtration apparatus which concerns on embodiment of this invention. It is a figure which shows the structure of an example of the water treatment apparatus which concerns on embodiment of this invention. It is a figure which shows the structure of the water treatment apparatus used in Example 1 , 2 and Comparative Examples 1,2 . It is a figure which shows the time-dependent change of the loss head with respect to water flow time in Example 1 , 2 and Comparative Examples 1,2 . It is a figure which shows the relationship between the consolidated length calculated | required from the height of the filled fiber in Examples 1 and 2, and Comparative Examples 1 and 2 , and SS capture | acquisition amount. It is a figure which shows the time-dependent change of the loss head when Example 1 and 2 and Comparative Examples 1 and 2 change the filtration rate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Filtration apparatus, 3 Water treatment apparatus, 10 Filtration tower, 12 Support body, 14 Long fiber bundle, 16 Raw water inflow pipe, 18 Treated water outflow pipe, 20 Backwash water inflow pipe, 22 Backwash drainage outflow pipe, 24 Air inflow pipe , 26 Raw water storage tank, 28 Treated water tank, 30 Blower, 32, 34, 36, 38, 40 Valve, 42 Raw water pump, 44 Backwash pump.

Claims (6)

A filtration device for capturing a suspension in raw water with a long fiber bundle,
A filtration tower;
A support horizontally or packed inside the filtration tower;
The lower end is fixed to the support, and the long fiber bundle having the upper end as a free end;
Have
Long fibers constituting the long fiber bundle has been crimped, number of crimps Ri der 9 / 25mm or more, the material of the long fiber filtration device, wherein the polyester der Rukoto. The filtration device according to claim 1,
The length of the long fiber is 20 μm or more and less than 80 μm. The filtration device according to claim 1 or 2 ,
The filtration device, wherein the filtration speed is 1000 m / day or more. A filtration method for capturing a suspension in raw water with a long fiber bundle,
While fixing the lower end of the long fiber bundle to the support, the upper end of the long fiber bundle is a free end, and filtration is performed by passing the raw water through the long fiber bundle in a downward flow,
Long fibers constituting the long fiber bundle has been crimped, number of crimps Ri der 9 / 25mm or more, the material of the long fiber filtration wherein the polyester der Rukoto. The filtration method according to claim 4 ,
The length of the said long fiber is 20 micrometers or more and less than 80 micrometers, The filtration method characterized by the above-mentioned. The filtration method according to claim 4 or 5 ,
The filtration method is characterized in that the filtration speed is 1000 m / day or more.

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