JP2013078713A - Filter device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a filter device which can display prescribed filtration performance by effectively utilizing a whole filter medium layer without involving selection of a filter medium matched to liquid to be treated.SOLUTION: The filter device carries out filtration treatment by allowing the liquid to be treated to pass through the filter medium layer constituted of an indefinite form filter medium, wherein the filter medium 4 which captures suspended solids and a filtering aid 5 which allows the liquid to be treated including suspended solids to pass therethrough are mixed to form the filter medium layer 3. In a filtration step, the liquid to be treated is easily allowed to pass through even to the inside of the filter medium layer via the filtering aid. Thereby both a filter medium layer surface and the inside of the filter medium layer can be effectively utilized for a filtration action to attain mass capturing of suspended solids, prevention of filtering pressure rise and increase in filtration duration time. Further the filter device is adaptable to various water to be treated only by changing a ratio of the filtering aid and SS ( Suspended Solid) concentration in the treated water can be adjusted too.

Description

  This invention is, for example, a filtration device that forms a filter medium layer using an irregular filter medium when separating and removing suspended substances contained in liquids to be treated such as domestic waste water (waste water) and factory waste water (waste water). Regarding improvements.

2. Description of the Related Art Conventionally, a filtration apparatus in which a filter medium layer is formed of an irregular granular filter medium has been widely used for solid-liquid separation and biological treatment apparatuses. Surface filtration that traps suspended substances in the liquid to be treated mainly on the surface of the filter medium layer. The suspended medium trapped on the surface of the filter medium layer accumulates, and even when the entire filter medium layer is not effectively used. Since clogging occurs in the layer and the filtration pressure rises in a short time, it is necessary to frequently wash the filter medium. When the water passage of the filter medium layer (the gap between adjacent filter media) is narrow, the balance of the filter medium layer becomes poor and surface layer filtration tends to occur. In depth filtration in which suspended substances in the liquid to be treated are trapped not only on the surface of the filter medium layer but also inside the filter medium layer, the filtration pressure of the filter medium layer is difficult to increase, and the amount of solid content captured per cycle is large. When the water passage through which the suspended substance can pass is formed up to the inside of the filter medium layer, the entire filter medium layer can be used effectively.
As an example of the filter medium constituting the filter medium layer, a filter medium layer with a certain thickness is formed with an irregular granular fiber filter medium with voids inside, and the suspension contained in the liquid to be treated inside and on the surface of the filter medium A filter device for capturing a substance has been proposed by the present applicant in Patent Document 1.
Sands and anthracites with different specific gravity and particle sizes are composed of multiple layers to capture large suspended solids with large gaps formed with large effective diameter particles, and small with small gaps formed with small effective diameter particles. Japanese Patent Application Laid-Open No. 2004-228867 proposes a filtration device that captures suspended substances.
In addition, by mixing a suitable amount of two types of filter media having different particle sizes (particle size a and particle sizes 3 to 5a) to form a filter medium layer, the filtration pressure is not increased so much and the filtration capacity is maintained for a long time. A filtration method capable of satisfying the requirements is proposed in Patent Document 3.

JP 2002-011305 A JP-A-7-284355 Japanese Patent Laid-Open No. 7-232007

When filtering with an irregular granular fiber filter medium, it is difficult to select a filter medium for the liquid to be treated. In the filter medium layer composed of the filter medium, the trapping zone for the suspended solids gradually advances from the surface of the filter medium layer along the flow direction of the liquid to be treated as time passes. Since the fiber filter medium is consolidated by the filtration pressure, the water passage is reduced.
When a fiber filter medium having a narrow water passage between the fibers constituting the filter medium is used, clarification filtration capable of capturing a large amount of suspended substances becomes possible. However, it becomes surface layer filtration which captures a large amount of suspended solids with the filter medium near the surface of the filter medium layer, and it is clogged early and the filtration pressure rises. Based on a predetermined filtration pressure or a predetermined filtration duration, the process proceeds to the cleaning step. However, since it is not effectively used for the filtering action up to the deepest part of the filter medium layer, the number of washing steps increases with respect to the amount of suspended substances trapped, and the processing amount decreases.
When a fiber filter medium having a wide water passage between the fibers constituting the filter medium or a fiber filter medium having a strength that does not compress by filtration pressure is used, depth filtration in which the trapping zone proceeds to the deepest part of the filter medium layer becomes possible. Although the filtration pressure does not rise very much, the water quality of the treatment liquid is poor, and suspended substances contained in the treatment liquid flow out together with the treatment liquid from the beginning of filtration (break-through phenomenon).

In the filtration device configured with multiple layers of particulate matter such as sand and anthracite with different specific gravity and particle size as filter media, the suspended particles contained in the liquid to be treated have a large particle size first captured by the coarse filter media layer, Sequentially, small particles are captured toward the fine filter medium layer. Although the depth filtration is performed effectively using the entire filter medium layer, the water passage in the filter medium tank is only the gap between the filter mediums, and the processing speed is slow. In the filter medium cleaning, it is necessary to inject a high-pressure fluid in the cleaning by backwashing. Further, in the cleaning by stirring, the specific gravity difference between the filter media must be increased so that the filters are formed in multiple layers after the cleaning. In this case, a large power is required for stirring the filter medium having a large specific gravity. There is a possibility that a lump of suspended solids in the gaps that cannot be loosened when washing the filter medium may remain in the packed bed.
A filter medium layer in which an appropriate amount of two types of filter mediums having different particle diameters (particle diameter a and particle diameters 3 to 5a) are mixed together adjusts the gap distribution between the filter media and efficiently traps suspended substances in the entire filter medium layer. Is. In the filter medium layer having only a large particle size (3 to 5a), the gap between the filter mediums is large, so that the depth filtration is performed. However, the trapped amount of suspended substances is small, and the breakthrough phenomenon is likely to occur. Conversely, a filter medium layer with only a small particle size (a) has a large amount of trapped suspended matter, but because the gap between the filter medium is narrow, surface filtration occurs, the filtration pressure increases in a short time, and frequent filter medium cleaning is required. It becomes. However, by mixing large and small particle sizes, the gaps between the filter media are averaged, and eventually the filtration performance is equivalent to that of the filter media layer composed of two types of average particle sizes.

By selecting a filter medium suitable for the properties and conditions of the liquid to be treated, it becomes a deep layer filtration and can exhibit a predetermined filtration performance. However, the liquids to be treated are various, including inorganic and organic. It is necessary to prepare a filter medium suitable for the porosity, filter medium strength, and the like inside the filter medium, which makes production and inventory management difficult.
The present invention provides a filtration device that does not easily cause a breakthrough phenomenon and that can be clarified and filtered while performing deep layer filtration with a long filtration duration without selecting a filter medium that matches the liquid to be treated.

The filtration apparatus according to the present invention is a filtration apparatus that performs filtration by passing a liquid to be treated through a filter medium layer constituted by an irregular shaped filter medium, and a liquid to be treated containing a suspended medium and a filter medium that captures the suspended substance. Because the filter aid that allows water to pass through forms a filter medium layer in a mixed state, the liquid to be treated is easily passed through the filter aid to the inside of the filter medium layer, so that not only the surface of the filter medium layer but also the filter medium layer The inside can be effectively used for filtering.
Specifically, the filter medium layer has a strength and a fiber filter medium having a function of adhering wave-shaped filaments to each other, having a large gap inside, and having a function of trapping suspended solids between the fibers. Since the filtration aid is configured by mixing filter aids with coarse fibers, the liquid to be treated is appropriately allowed to flow into the filter medium layer, and depth filtration using the entire filter medium layer can be performed.

Moreover, since the said filter aid has an internal space | gap larger than a filter medium during filtration operation, even if a filtration pressure rises and a filter medium layer is consolidated, the water flow path to the inside of a filter medium layer can be ensured through a filter aid. If fibers are raised on a part of the filter aid and the suspended substances can be captured by the fibers, the suspended substances can be effectively captured in the gap between the filter medium and the filter aid, and clarification filtration can be promoted.

Since the filter medium and the filter aid are mixed evenly in the filter medium layer, the to-be-treated liquid containing the suspended substance can be appropriately introduced into the filter medium layer, and the depth filtration using the entire filter medium layer can be performed. When a large amount of filter aid is mixed in the upstream surface layer of the filter medium layer, it is possible to prevent an increase in the filtration pressure near the surface layer where the filter medium is likely to be clogged. Deep layer filtration using the entire filter medium layer can be performed.

The filter medium layer forming the filtration device of the present invention includes a filter medium that captures suspended substances contained in the liquid to be treated, and a filter aid that allows the liquid to be treated containing suspended substances to flow downstream of the filter medium layer. It is composed by mixing. In the filtration process, the liquid to be treated is easily passed through the filter aid to the inside of the filter medium layer, so that not only the surface of the filter medium layer but also the inside of the filter medium layer can be effectively used for the filtration action, and a large amount of suspended matter can be obtained. Capturing, preventing increase in filtration pressure, increasing filtration duration, and clarifying filtration become possible. Moreover, it can respond to various to-be-processed water only by changing the ratio which mixes a filter aid, it is not necessary to change to the filter material of a different specification, and adjustment of SS concentration of treated water is also possible.

It is a schematic block diagram of the filter medium layer of the filtration apparatus concerning this invention. Similarly, it is a downward flow type filtration device. Similarly, it is the upflow type filtration apparatus of another Example. Similarly, it is the schematic of a rectangular fiber filter medium. Similarly, it is the schematic of a spherical fiber filter medium. Similarly, it is a schematic view of a molding fiber filter medium. Similarly, it is the schematic of a cylindrical fiber filter medium. Similarly, it is a schematic diagram of a rectangular filter aid. Similarly, it is the schematic of a spherical filter aid. Similarly, it is a schematic diagram of a molding filter aid. Similarly, it is the schematic of a cylindrical filter aid. Similarly, it is a partially enlarged view of the filter medium layer. Similarly, it is a schematic block diagram of the filter medium layer disperse | distributed to the surface layer of another Example. It is a comparison table of the filtration pressure and filtration continuation time concerning this invention and a prior art.

The filtration device according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of a filter medium layer, in which a filter medium 4 is filled with a filter medium 4 and a filter aid 5 and mixed. Is forming. When the specific gravity of the filter medium 4 and the filter aid 5 is 1.0 or more, the filter medium layer 3a is formed below the filter tank 2, and it becomes the downward flow type filter apparatus 1a shown in FIG. When the specific gravity of the filter medium 4 and the filter aid 5 is less than 1.0 respectively, the filter medium layer 3b is formed above the filter tank 2, and it becomes the upward flow type filter apparatus 1b shown in FIG.

4 to 7 are schematic views of the irregular shaped filter medium according to the present invention. In this embodiment, the filter media 4 are bonded to each other with wave-like filaments and are composed of fiber filter media having a large gap inside. Since the liquid to be treated can pass through the internal space of the filter medium 4 together with the suspended substance, high-speed filtration can be performed. Between the fibers inside the filter medium 4 is densely configured, and suspended substances can be captured between the fibers inside the filter medium 4. Since fibers are raised on the surface of the filter medium 4, suspended substances passing through the gaps between the filter media 4 and 4 can be captured also on the surface of the filter medium 4.
When forming the filter medium layer 3 and passing the liquid to be treated, the fiber filter medium 4 having voids therein is appropriately compressed and filled, so that the gap between the filter media 4 and 4 can be kept uniform, It can be filtered efficiently.

FIG. 4 shows an irregular rectangular fiber filter medium, which can be formed into a rectangular shape by cutting the medium into a regular shape from a large mat-shaped medium. Since the filter medium 4 is composed of fibers, suspended substances can be captured between the napped fibers on the surface of the rectangular fiber filter medium 4a or the fibers inside the rectangular filter medium 4a. When the filter medium layer 3 is formed by filling the rectangular fiber filter medium 4a into the filter tank 2, a large and small gap is formed between the filter mediums 4a and 4a, and the liquid to be treated is brought into the filter medium layer 3 while trapping suspended substances. And let water through.
FIG. 5 shows an irregular filter medium according to another embodiment, in which the filter medium is formed in a spherical shape. Since it is composed of fibers in the same manner as the rectangular fiber filter medium 4a, suspended substances can be captured between the napped fibers on the surface of the spherical fiber filter medium 4b or the fibers inside the spherical fiber filter medium 4b.

FIG. 6 shows an irregular filter medium according to another embodiment, in which the filter medium is formed in a molding shape. Like the rectangular fiber filter medium 4a, it is composed of fibers, so that suspended substances can be captured between napped fibers on the surface of the molding fiber filter medium 4c or fibers inside the molding fiber filter medium 4c.
FIG. 7 shows an irregular filter medium according to another embodiment, in which the filter medium 4 is formed in a cylindrical shape. Since it is composed of fibers in the same manner as the rectangular fiber filter medium 4a, suspended substances can be captured between the napped fibers on the surface of the cylindrical fiber filter medium 4d or between the fibers in the cylindrical fiber filter medium 4d.

8 to 11 are schematic views of the irregular filter aid according to the present invention. The filter aid 5 of the present embodiment is rough between fibers and has a sufficient gap or opening for the liquid to be treated containing suspended substances to pass from one to the other of the filter aid 5. Since the filter aid 5 is mixed in the filter medium layer 3 formed of the filter medium 4, the suspended substances not captured by the filter medium layer 3 on the upstream side of the filter aid 5 are passed along with the liquid to be treated to the downstream side. Let Then, the suspended matter that has passed through the inside of the filter aid 5 is captured by the filter medium layer 3 on the downstream side.
Even if many suspended substances are trapped on the surface of the filter medium layer 3, the filter aid 5 is mixed in the filter medium layer 3, so that a water passage to the filter medium layer 3 can be secured and the filtration pressure increases. It is hard to do. The filter aid 5 guides the liquid to be treated to the inside of the filter medium layer 3 and promotes the depth filtration inside the filter medium layer 3. One filtration time can be set longer, and the throughput increases.

The filter aid 5 is formed with a structure that can maintain its shape even after being compacted, for example, a structure having a strength or a fiber diameter is increased. Specifically, the filter aid 5 may be formed of synthetic resin such as plastic or synthetic fiber.
The inside of the filter aid 5 has a much larger gap than the filter medium 4, and the opening leading to the inside has at least two or more. The internal space and opening of the filter aid 5 are large enough to allow the liquid to be treated containing suspended substances to pass through. The liquid to be treated containing the suspended substance flows into the inside from one opening of the filter aid 5 and flows out from the other opening through the internal gap. The shape, size, etc. are not specified as long as the size allows water to pass from the opening through the internal space of the filter aid 5 to the downstream side of the filter medium layer 3. It is desirable to provide two or more openings at the symmetrical positions for communication between the inside and the outside.
Even if the members constituting the filter aid 5 are consolidated inside the filter medium layer 3, they are not easily deformed by compression. Therefore, even during the filtration operation, the filter medium layer 3 can always secure a water passage by the gap inside the filter aid 5.
If the size of the filter aid 5 is substantially the same as that of the filter medium 4, the gap between the filter media 4, 4 and the gap between the filter medium 4 and the filter aid 5 are almost equal, and the trapped amount of suspended substances in the filter medium layer 3 Is less likely to occur.
Further, a part of the filter aid 5, for example, a surface may be raised to make it possible to capture suspended substances on the surface of the filter aid 5.

FIG. 8 shows an irregular rectangular filter aid, which is produced in the same manner as the rectangular fiber filter media 4a, but the rectangular filter aid 5a roughly forms the space between the fibers. The interior has a sufficient space through which the liquid to be treated containing suspended substances can pass. The strength of the filter aid 5 may be increased by thickening the fibers constituting the filter aid 5 so that the shape of the liquid to be treated is not deformed by the water flow pressure when the liquid to be treated is passed.
FIG. 9 shows an irregular filter medium according to another embodiment, in which the filter medium aid 5 is formed in a spherical shape. Although it produces | generates similarly to the spherical fiber filter medium 4b, the spherical filter aid 5b has comprised between the fibers roughly.

FIG. 10 shows an irregular filter medium according to another embodiment, in which the filter medium assistant 5 is formed in a molding shape. Although it produces | generates similarly to the molding fiber filter medium 4c, the molding filter aid 5c comprises between the fibers roughly.
FIG. 11 shows an irregular filter medium according to another embodiment, in which the filter medium aid 5 is formed in a cylindrical shape. Although it produces | generates similarly to the cylindrical fiber filter medium 4d, the cylindrical filter aid 5d has comprised between the fibers roughly.

FIG. 12 is a partially enlarged view of the filter medium layer, and the filter aid 5 is mixed in the granular filter medium 4.
When the liquid to be treated is passed through the filter medium layer 3, a large amount of suspended substances are captured by the filter medium 4 located near the surface of the filter medium layer 3. The treated liquid from which suspended substances have been removed and the liquid to be treated containing a part of suspended substances include a gap between the filter media 4 and 4, a gap inside the filter medium 4, a gap between the filter medium 4 and the filter aid 5, or a filter aid. It passes through the voids inside the material 5 and flows into the filter medium layer 3. At that time, suspended substances are trapped in the gaps in the filter medium 4 or in the gaps between the filter media 4 and 4. Therefore, the trapped amount of suspended substances in the filter medium layer 3 decreases from the upstream side to the downstream side of the filter medium layer 3.
The filter medium 5 is mixed with the filter aid 5, and the liquid to be treated can easily pass through the filter aid 5. If the filter medium 4 is present on the downstream side after passing through the filter aid 5, suspended substances are trapped according to the gaps of the filter medium 4 or the gaps between the filter media 4 and 4. Further, the liquid to be treated passes through the gap between the filter media 4, 4, the gap inside the filter medium 4, the gap between the filter medium 4 and the filter aid 5, or the gap inside the filter aid 5, and flows into the filter medium layer 3. Suspended substances are captured by the filter medium 4 inside the filter medium layer 3.
Thus, by allowing the liquid to be treated containing suspended substances to flow through the filter medium 5 through the filter aid 5, the filter medium layer 3 can be efficiently filtered and the entire filter medium layer 3 can be effectively used. It can be an available depth filtration.

As shown in FIG. 1, the specific gravity of the filter medium 4 and the filter aid 5 is 1.0 or more and less than 3.0 in the case of the downward flow type filtration device 1a, and the case of the upward flow type filtration device 1b. If both are 0.1 or more and less than 1.0, they are appropriately dispersed.
As described above, when the difference in specific gravity between the filter medium 4 and the filter aid 5 is set to be small, and when the filter medium 4 and the filter aid 5 having the same shape are used, washing and stirring are performed as shown in FIG. Are evenly mixed to form the filter medium layer 3.

When the filter medium 4 and the filter aid 5 are set so that the specific gravity difference is greatly different, or when the filter medium 4 and the filter aid 5 having different shapes are used, if the stirring and washing are performed, the filter medium layer 3 is different due to the difference in specific gravity and shape. The filter medium 4 or the filter aid 5 can be deviated and mixed on one side (upstream side or downstream side).
Specifically, as shown in FIG. 13, when the filter aid 5 is distributed on the upstream side of the filter medium layer 3, the filtration pressure in the vicinity of the surface layer, which is likely to clog the filter medium 4, is prevented. The suspended liquid can be captured by positively flowing the liquid to be treated into the filter medium layer 3.

By adjusting the mixing ratio of the filter medium 4 and the filter aid 5, it is possible to cope with various liquids to be treated, and it is not necessary to prepare various filter media 4 having different porosity and size. By adjusting the pressure density of the filter medium layer 3 according to the conditions, the porosity inside the filter medium 4 and the gap between the filter media 4 and 4 can be set.
When the specific gravity is 1.0 or more, the filter medium layer 3a is settled in the lower part of the filtration tank 1a, so that the liquid to be treated is caused to flow by the downward flow. When the specific gravity is less than 1.0, the filter medium layer 3b floats on the upper part of the filtration tank 1b.

In FIG. 2, 1a is a downflow type filtration apparatus. A filter medium outflow prevention screen 6 for preventing the filter medium 4 and the filter aid 5 from flowing out to a predetermined height from the lower end is installed in the filtration tank 2. A filter medium layer 3 a having a predetermined thickness is formed on the upper side of the filter medium outflow prevention screen 6 by the filter medium 4 and the filter aid 5. When forming the filter medium layer 3a with the filter medium 4 and the filter aid 5, since the fiber filter medium 4 is appropriately compressed and filled, the gaps between the filter mediums 4 and 4 can be kept uniform and filtered efficiently. Can do.
The treated liquid supply pipe 7 is connected to the filtration tank 2 so as to supply the treated liquid to the upper side of the filter medium layer 3a.
The cleaning device 8 corresponds to the lower part of the filter medium layer 3a, that is, corresponds to the upper part of the filter medium outflow prevention screen 6, so that the filter medium 4 constituting the filter medium layer 3a can be stirred and cleaned with the supplied air. It is connected to the filtration tank 2.
A discharge pipe 9 that discharges a liquid to be treated (water to be treated) and the like is connected to a lower portion of the filtration tank 2 than the filter medium outflow prevention screen 6.

Next, an example of filtration in the filtration device 1a will be described.
By supplying the liquid to be processed into the filtration tank 2 from the liquid supply pipe 7 to be processed, the liquid to be processed descends in the filter medium layer 3 a and is filtered and discharged through the discharge pipe 9.
And, for example, when the filtration pressure rises due to clogging by suspended substances trapped in the filter medium layer 3a, or when the accumulated operation time reaches a predetermined time, or the treatment liquid does not reach a predetermined standard. If so, air is supplied from the cleaning device 8.
In this way, when the liquid to be treated and air are supplied into the filtration tank 2, the filter medium 4 is agitated by the air, whereby the filter medium 4 is washed, and the suspended substances trapped by the filter medium 4 are separated and settled. , And discharged through the discharge pipe 9. Since the filter medium 4 and the filter aid 5 have substantially the same size, specific gravity, and the like, the filter aid 5 is similarly stirred when the filter medium 4 is washed. In addition, when washing | cleaning the filter medium 4, the washing | cleaning liquid (washing water) supplied in the filtration tank 2 may reach a predetermined | prescribed reference | standard, and may supply washing water, for example, a processing liquid (treatment water).

FIG. 3 is a schematic configuration diagram showing another embodiment of the filtration device of the present invention. The same or corresponding parts as those in FIG.
In FIG. 3, 1b is an upflow type filtration apparatus. A filter medium outflow prevention lower screen 6 a for preventing the filter medium from flowing out below the filter tank 2 is installed in the filter tank 2, and the filter medium for preventing the filter medium 4 from flowing out above the filter tank 2. An outflow prevention upper screen 6b is provided. A filter medium layer 3b having a predetermined thickness is formed by the filter medium 4 and the filter aid 5 below the filter medium outflow prevention upper screen 6b.
The treated liquid supply pipe 7 is connected to the filtration tank 2 so as to supply the treated liquid to the lower side of the filter medium outflow prevention lower screen 6a.
The cleaning device 8 is connected to the filtration tank 2 corresponding to the upper portion of the filter medium outflow prevention lower screen 6a so that the filter medium constituting the filter medium layer 3b can be stirred and cleaned with the supplied air.
A discharge pipe 9 that discharges a liquid to be treated (water to be treated) or the like is connected to a lower part of the filtration tank 2 from the lower screen 6a for preventing the outflow of the filter medium.
A processing liquid discharge pipe 10 for discharging the processing liquid (process water) is connected to the upper side of the filter medium outflow prevention upper screen 6 b of the filtration tank 2.
In addition, the filter medium 4 and the filter aid 5 used for this filtration apparatus 1b use the filter medium 4 and the filter aid 5 whose specific gravity is less than 1.0.

Next, an example of filtration in the filtration device 1b will be described.
By supplying the liquid to be processed into the filtration tank 2 from the liquid supply pipe 7 to be processed, the liquid to be processed is filtered upward in the filter medium layer 3 b and discharged through the processing liquid discharge pipe 10.
And, for example, when the filtration pressure increases due to clogging by suspended substances trapped in the filter medium layer 3b, or when the accumulated operation time reaches a predetermined time, or the treatment liquid does not reach a predetermined standard. If so, air is supplied from the cleaning device 8.
In this way, when the liquid to be treated and air are supplied into the filtration tank 2, the filter medium 4 is agitated by the air, whereby the filter medium 4 is washed, and the suspended substances trapped by the filter medium 4 are separated and settled. , And discharged through the discharge pipe 9. In addition, when washing | cleaning the filter medium 4, the washing | cleaning liquid (washing water) supplied in the filtration tank 2 may reach a predetermined | prescribed reference | standard, and may supply washing water, for example, a processing liquid (treatment water).
The filter medium 4 can also be applied to a closed-type upstream flow filtration device, exhibits the same filtration performance, and can obtain the same cleaning effect even when the filter medium is washed with a stirring blade.

A comparative test was performed with a downflow type filtration device using a conventional filter medium layer composed only of an irregular filter medium and a filter medium layer composed of a mixture of the irregular filter medium of the present invention and a filter aid. The filter media, the filter aid, and the filtration device have the following specifications.
Liquid to be treated: Agglomerated pond water or pond water filter medium containing algae: Mall-shaped fiber filter medium 4c
Filter aid: Mall-shaped filter aid 5c
Body tank height: 4000mm
Body tank inner diameter: Φ600mm
Water flow speed: 40 m / h

FIG. 14 is a comparison table of the filtration pressure and the filtration duration according to the present invention and the prior art, wherein the vertical axis is the filtration pressure (kPa) and the horizontal axis is the filtration duration (h). When the filtration pressure is increased to 15 kPa, in order to remove suspended substances from the filter medium 4, it is necessary to clean the filter medium.

In the filter medium layer comprised only with the conventional filter medium 4, the filtration pressure is rising to 15 kPa in 4.5 hours. This indicates that the filter medium needs to be cleaned every 4.5 hours.
On the other hand, in the filter medium layer 3 formed by mixing the filter medium 4 and the filter aid 5 of the present invention, the time until the filtration pressure rises dramatically increases.
Specifically, in the filter medium layer 3 ′ in which the filter medium 4 is 90% and the filter aid 5 is 10%, the filtration pressure rises only to 6 to 7 kPa in 4.5 hours. It takes 7 hours for the filtration pressure to rise to 15 kPa. In addition, the SS density | concentration in the process liquid after the filtration process after 7 hours did not have a difference with a prior art and this invention.
Moreover, in the filter medium layer 3 ″ in which the filter medium 4 is 80% and the filter aid 5 is 20% and mixed uniformly, it takes 8.5 hours for the filtration pressure to rise to 15 kPa. However, when 4 hours passed, the SS concentration in the treatment liquid after the filtration treatment increased rapidly, and a breakthrough phenomenon was confirmed.

The filter medium layer composed only of the conventional filter medium 4 has a narrow gap between the filter media 4 and 4 and a narrow gap inside the filter medium 4, so that a large amount of the filter medium 4 is deposited in the vicinity of the surface of the filter medium layer in a short time. Capture suspended material. However, due to the trapping of the suspended matter, the water passage area of the filter medium 4 decreases, and the filtration pressure rises in a short time as a filtration device.
On the other hand, in the filter medium layer 3 formed by mixing the filter medium 4 and the filter aid 5, the liquid to be treated is passed through the filter aid 5 into the filter medium layer 3. In particular, in the filter medium layer 3 in which 10% of the filter aid 5 is mixed, even if the suspended substances are captured by the filter medium 4 near the surface of the filter medium layer 3, water is appropriately passed through the filter aid 5 into the filter medium layer 3. A passage is secured. Then, in the liquid to be treated which is passed through the filter aid 5, suspended substances are captured by the filter medium 4 on the downstream side of the filter aid 5. As a result, since the entire filter medium layer 3 is effectively used, the filtration area is large, and the increase in the filtration pressure becomes gradual.
In addition, when the ratio of the filter aid 5 is increased, a lot of suspended substances may be trapped on the downstream side of the filter medium layer 3, and the breakthrough phenomenon is likely to occur. Moreover, the filter aid 5 may be connected from the upstream to the downstream of the filter medium layer 3 to form a water passage, and the SS concentration in the treatment liquid may increase.
The mixing ratio of the filter medium 4 and the filter aid 5 may be appropriately selected according to the properties of the liquid to be treated, the amount of treated water, and the filtration device. Considering the rise time of the filtration pressure and the breakthrough phenomenon, the mixing ratio of the filter medium 4 and the filter aid 5 is desirably 9.5 to 7.0: 0.5 to 3.0.

By adjusting the mixing ratio of the filter medium and the filter aid, the function of the filter medium layer can be optimized according to the properties of the liquid to be processed and the processing conditions. The entire filter medium layer can be effectively used for special applications that require high clarity.

1 Filtration device 3 Filter media layer 4 Filter media 5 Filter aid

Claims (6)

In a filtration device that performs filtration by passing the liquid to be treated through a filter medium layer composed of irregular shaped filter media,
The filter medium (4) for trapping suspended substances and the filter aid (5) for passing water to be treated containing suspended substances form a filter medium layer (3) in a mixed state. Filtration equipment to do. The filter medium layer (3)
A fiber filter medium (4) having a function of adhering wavy filaments to each other, having a large gap inside, and having a dense space between fibers and capturing suspended solids;
The filtration device according to claim 1, wherein the filtration device (1) is configured by mixing filter aids (5) having coarse strength between fibers. The filtration device according to claim 1, wherein the filter aid (5) has a larger internal void than the filter medium (4) during the filtration operation. The fiber is raised in a part of the filter aid (5),
The filtration device according to any one of claims 1 to 3, wherein suspended fibers can be captured by the fibers. The filtration device according to any one of claims 1 to 4, wherein the filter medium (4) and the filter aid (4) are mixed evenly in the filter medium layer (3). The filtration apparatus according to any one of claims 1 to 4, wherein a large amount of the filter aid (5) is mixed in an upstream surface layer of the filter medium layer (3).

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