JP3489397B2 - Activated sludge filtration device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an activated sludge filtration device, and more particularly to activated sludge filtration that efficiently separates activated sludge to obtain biologically treated water by a plurality of filter bodies immersed in a biological reaction tank. Regarding the device.

[0002]

2. Description of the Related Art A biological treatment apparatus for decomposing organic matter in water by a biological reaction such as activated sludge may sometimes use a sedimentation separation means such as a sedimentation tank for solid-liquid separation of the biological sludge. The conventional biological treatment device having a sedimentation tank in the latter stage has the following problems.

In the sedimentation treatment in which sludge is sedimented and separated due to the difference in specific gravity, sludge separation performance is limited, and the quality of treated water deteriorates when the inflow load changes or when bulking occurs. Therefore, if a high quality of treated water is required, further equipment such as a rapid filter and a strainer is required after the settling basin. It is also necessary to return the biological sludge separated in the final settling tank to the biological reaction tank. Even if sludge return operation and sludge concentration control are performed, water quality often deteriorates due to problems such as scum generation in the final settling tank and sludge floating. The sedimentation tank requires a large equipment space. Ultrafiltration (UF) of biological sludge instead of the above settling separation
Membrane separation may be performed using a membrane or a microfiltration (MF) membrane.
According to this membrane separation treatment, it is possible to obtain high-quality treated water from which SS is highly removed, without requiring a large space such as a sedimentation tank.

However, in the membrane separation treatment using the UF membrane or the MF membrane, the consumption power is large and the substance blocked by the membrane (the membrane contaminant is mainly composed of macromolecular microbial metabolites and the like). ) Contaminates the membrane, and the membrane pores are clogged to lower the filtration performance. Therefore, regular chemical cleaning is essential.

In order to solve such a problem in the membrane separation treatment, a filter body provided with a filter cloth is immersed in a biological reaction tank and the filtered water that has passed through the filter cloth of the filter body is taken out as treated water. , An activated sludge filtration device for solid-liquid separation of biological sludge has been proposed. Usually, the filter body is
Plural units are immersed in the biological reaction tank and treated water is taken out from each filter.

[0006] The filtration by the filter body is actually a layer of deposits of activated sludge particles formed on the surface of the filter cloth of the filter body by the progress of filtration (dynamic filter layer; hereinafter simply referred to as "filter layer"). There is). That is, the filter cloth of the filter body is made of a non-woven fabric of metal or polymer fiber and has a thickness of 1 mm or less, which substantially allows activated sludge particles to pass therethrough. An adhered layer of activated sludge particles is formed on the surface of the
This layer of adhering matter can prevent the passage of activated sludge particles.

In the treatment with such an activated sludge filtration device, the adhering material layer of activated sludge particles as a filtration layer on the surface of the filter cloth of the filter body has a thickness and a pressure density suitable for the filtration of the activated sludge. Such efficient formation is important for surely blocking the passage of activated sludge particles and stably obtaining treated water of good water quality.

[0008]

In such an activated sludge filtration device, by increasing the number of filter bodies to be immersed and arranged in the biological reaction tank, the amount of water taken increases, the treatment efficiency is improved, and the unit Although the number of filter bodies per area increases, space can be saved as a result, but if the number of filter bodies installed in the biological reaction tank becomes excessively large, a filter layer effective for filtration of activated sludge is formed. Unable to
There has been a problem that the quality of treated water is deteriorated or the amount of treated water is significantly reduced.

The present invention solves the above-mentioned conventional problems and efficiently separates the activated sludge by forming a good adherent layer of the activated sludge on a plurality of filter bodies immersed in the biological reaction tank. An object of the present invention is to provide an activated sludge filtration device that can stably obtain high-quality treated water.

[0010]

In the activated sludge filter of the present invention, a plurality of filter bodies each having a filter cloth through which the activated sludge passes are immersed in an activated sludge mixed solution in a biological reaction tank, and the activated sludge is filtered.
In the activated sludge filtration apparatus for filtering the active sludge mixture to form a deposit layer of biological sludge to the surface of the fabric, filtrate cloth
Is a metal or polymer material and has a separation particle size of 30 to 10
Non-woven with openings of 00 μm and thickness of 0.1 to 1 mm
The cloth is a cloth, the distance between the filter bodies is 8 mm or more, and the crossflow flow velocity passing between the filter bodies is 0.05 to
It is characterized by being 0.3 m / sec.

For filtration by the dynamic filtration layer, it is necessary to form a layer of activated sludge particles or flocs gently on the surface of the non-woven fabric (filter cloth) of the filter body. If the flow velocity is too high, the shearing force will be strong on the non-woven fabric surface, and a good dynamic filtration layer will not be formed. Therefore, activated sludge particles and suspended matter will pass through the non-woven fabric and be mixed into the filtered water, resulting in good water quality treatment. I can't get water.

The upper limit of this flow velocity is around 0.4 m / sec with respect to the cross-sectional area between the filters, and if the flow velocity is less than this, particles of activated sludge and flocs form a layer gently on the surface of the nonwoven fabric. And good treated water can be obtained.

The inventors of the present invention have conducted extensive studies on the intervals between filter bodies, the cross flow velocity, and the state of formation of a dynamic filter layer. As a result, when a plurality of filter bodies are installed in a biological reaction tank, the adjacent filter bodies are filtered. It was found that when the space between the bodies is narrow, the dynamic filtration layer is not formed unless the crossflow velocity is reduced. This is the stress (shear rate) on the dynamic filtration bed depending on the cross flow velocity.
This is because the stress is inversely proportional to the distance between the filter bodies, and if the distance between the filter bodies is 8 mm or more, the dynamic filter layer is less affected by the stress and can be used at a practical cross flow velocity. It was found that it could be done.

That is, if the distance between the plurality of filter bodies immersed in the biological reaction tank is narrow, the flow rate must be lowered to form the dynamic filter layer. The upper limit of the flow velocity at which the dynamic filtration layer can be formed becomes lower in proportion to the distance between filter bodies of 8 mm or less. This is because a stress called shear rate acts on the nonwoven fabric surface. This shear rate is expressed by the following equation (1) (WF
Blatt et al., Membrane Science and Technology, Ed.by
JEFlinn, Prenum Press, 47 (1970)), it is found that the shear rate increases as the distance between the filter bodies decreases.

Shear velocity (sec ⁻¹ ) = 3 du / dy (1) However, u; Cross flow velocity y; Distance from the center of the flow The shear velocity is 150 to 200 sec ⁻¹ or less, which is good dynamic. A filtration layer can be formed and good filtered water can be obtained.

Even if the distance between the filter bodies is narrower than 8 mm, a dynamic filtration layer can be formed by slowing the cross-flow velocity. For example, if the flow velocity is less than 0.05 m / sec, the biological reaction in which the filter bodies are immersed. Activated sludge may be deposited in the tank, which interferes with operation. For this reason,
The flow velocity in which a filtration layer can be formed and there is no problem of activated sludge sedimentation is in a very limited range. It is not desirable that the filtration flow rate that can be adopted is limited to a narrow range because operation management becomes difficult. In addition, the amount of aeration varies with the load in ordinary activated sludge treatment methods such as sewage treatment, but when the filter is immersed in the descending flow velocity part of the aeration tank, the crossing that passes between the filters is performed. Flow velocity
Of 0.05 to 0.3 m / sec gives a stable filter.
In the present invention, this filtration flow rate forming the dynamic filtration layer is set to 0.05 to 0.3 m / s.
ec.

In the conventional activated sludge membrane filtration method, it is necessary to increase the flow rate of the activated sludge mixed solution in order to form a cake layer on the membrane surface and prevent the deposition of membrane contaminants. 1000 by extra-tank type UF membrane filtration of human waste treatment
~ 2500sec ^-1 , MF, which is said to be energy saving
Even with immersion suction filtration using a membrane, it is 400 to 500 sec ⁻¹ or more.

Since the filtration method using the dynamic filtration layer is performed by forming a gentle filtration layer of activated sludge on the surface of the non-woven fabric, the conventional UF filtration outside the tank or the aeration layer immersion type using the MF membrane is used. Unlike the membrane filtration method, it is not necessary to apply a strong shearing force due to strong aeration from below in order to prevent the contamination of the membrane surface, and on the contrary, such a shearing force hinders the filtration.

As described above, the filtration method using the dynamic filtration layer is a preferable method from the viewpoint that an operation requiring little energy for obtaining filtered water and preventing pollution can be performed.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an activated sludge filtration device of the present invention will be described below with reference to the drawings.

First, the filter body used in the activated sludge filter of the present invention will be described with reference to FIGS.

FIGS. 1 and 2 are views showing an example of a filter body suitable for the activated sludge filter of the present invention, in which (a) is a partially cutaway front view and (b) is (a). ) A schematic cross-sectional view taken along the line BB in the figure.

In the filter body 1 of FIG. 1, a nonwoven fabric 4 is attached to both sides of a plate-like support body 2 via spacers 3 and fixed by an attachment frame 5. The support body 2 is provided with two communication pipes 21 at two locations in the thickness direction thereof, the communication tubes 21 communicating with both plate surfaces. The communication pipe 21 is communicated from the end face side of the bottom of the support body 2,
A filtered water take-out pipe 22 which also serves as a wash water inflow pipe is provided.

In the filter body 1A shown in FIG. 2, the support body 2A is
The portion facing the non-woven fabric 4A is made of a frame-shaped member that becomes the hollow portion 2B. Spacer 3 so as to cover this cavity 2B
The nonwoven fabric 4A is attached via A and is fixed by the attachment frame 5A. Further, two cleaning water inflow pipes 22A are provided which communicate with the cavity 2B of the support body 2A from the end surface side of the upper portion of the support body 2A, and the support body 2 is provided from the end surface side of the bottom portion of the support body 2A.
Two filtered water extraction pipes 22B communicating with the hollow portion 2B of A are provided.

The support is not particularly limited as long as it supports a non-woven fabric as a filtration member and has sufficient rigidity to withstand water pressure when immersed in an activated sludge filtration device. For example, a plate-shaped body or a frame-shaped body made of metal such as copper, ABS resin, synthetic resin such as polyester, or ceramics such as aluminum oxide is preferable.

The non-woven fabric is made of a metal such as copper or a polymer material such as polyester or polypropylene, has a mesh size of 30 to 1000 μm, and has a thickness of 0 . 1 to 1 mm is used. Such non-woven fabric
Is preferable for preventing clogging of the nonwoven fabric and performing stable filtration.

As the spacer, various kinds such as a net spacer can be used. When the plate-shaped support 2 is used as shown in FIG. 1, the nonwoven fabric 4 and the support 2 are used.
In order to secure the flow path of the filter body between and, a material such as a honeycomb net spacer is suitable. In the case of the support 2A having the cavity 2B as shown in FIG. 2, a wire mesh spacer may be used.

In the filter bodies 1 and 1A, the filtered water that has passed through the nonwoven fabrics 4 and 4A has a communication pipe 21 and an extraction pipe 2.
2 or through the hollow portion 2B of the support 2A and the extraction pipe 22B.

When the filtration is continued, turbidity and activated sludge particles are gradually accumulated in the portion of the filter body where the flow of filtered water is bad, and when the filtration performance is deteriorated, these are removed from the filter body. In order to do so, wash water is supplied to wash the inside of the filter body. That is, in the filter body 1 of FIG. 1, the wash water is supplied from the extraction pipe 22, and the nonwoven fabric 4 is passed through the communication pipe 21, so that the extraction pipe 22, the communication pipe 21, the spacer 3 or the spacer 3 and the support 2 are provided. Alternatively, suspended matter or the like with the non-woven fabric 4 is discharged to the reaction liquid side of the activated sludge filter through the non-woven fabric 4. Further, in the filter body 1A shown in FIG. 2, washing water is supplied from the inflow pipe 22A and discharged from the take-out pipe 22B to wash out suspended matters and the like in the filter body 1A.

In the present invention, a plurality of such filter bodies are arranged in parallel in a biological reaction tank and immersed therein. In that case, the following method may be adopted as the method for installing the filter bodies. it can.

A plurality of filter bodies are fixed to each other. The upper and lower parts of the plurality of filter bodies are fixed by a supporting member. As shown in FIG. 3 (plan view), a rectangular tubular frame member 6 supports and fixes the filters 6A, 6B, 6C and 6D as shown in FIGS. As shown in FIGS. 4 (a) (plan view) and (b) (side view), the filter bodies 11A, 11B, 11C, 11D are arranged in parallel at appropriate intervals, and are provided above the respective filter bodies 11A-11D. Cleaning water inflow collecting pipe 13 communicating with the cleaning water inflow pipes 12A, 12B, 12C and 12D, and the respective filtration bodies 11A to 11D.
Filtered water extraction pipes 14A, 14B, 14 provided in the lower part of the
The filter body 1 is provided with a filtered water extraction collecting pipe 15 that communicates C and 14D.
Connect 1A-11D.

The filter body is not limited to the plate-like one as described above, but may be a cylindrical filter body 7A, 7B, 7C obtained by molding a filter cloth into a cylindrical shape as shown in FIG. .

In the present invention, the distance between the filter bodies (the distance d between the filter cloth surfaces of the adjacent filter bodies in the plate-like filter bodies of FIGS. 3 and 4 and the shortest of the cylindrical surface in the cylindrical filter body of FIG. 5). The distance d) is a value of 8 mm or more and is determined depending on the raw water quality, the permissible water quality (turbidity) of treated water, other water flow conditions, etc., but preferably 10 mm or more, more preferably 1
It is 2 mm or more. When the distance between the filter bodies is 8 mm or more, a good dynamic filtration layer is formed in a filtration flow rate range of 0.05 to 0.3 m / sec, and filtered water of high quality can be efficiently obtained.

It should be noted that the larger the spacing between the filter bodies is, the more advantageous it is for the formation of the dynamic filter layer. However, from the standpoint of space saving by arranging a large number of filter bodies in the biological reaction tank, The distance between them is preferably 100 mm or less.

A treatment method by the activated sludge filter of the present invention will be described below with reference to FIG. 6 showing an embodiment of the activated sludge filter of the present invention.

In this embodiment, four filter bodies are connected so that the distance between the filter bodies is 8 mm or more to form a filter body unit 30, which is immersed in one side of the biological reaction tank 31. I placed it. The structure of each filter used is as shown in FIG. The connecting structure is as shown in FIG. In addition, 30A of FIG. 6 is a filtered water extraction collecting pipe, and 30B is a wash water inflow collecting pipe.

On the other side of the biological reaction tank 31, there is provided an air diffusing pipe 32 for supplying oxygen necessary for biological reaction. A ventilation pipe 33 is provided below the filter body unit 30.
Is provided. 34 is a partition wall.

Reference numeral 35 denotes a treated water (filtered water) tank. The treated water in the treated water tank 35 is pumped up by a water supply pump 36 and stored in a water supply tank 37, and this water is passed through a wash water inflow collecting pipe 30B to a filter body. It is configured to supply each filter body of the unit 30.

V ₁ , V ₂ , V ₃ , and V ₄ are valves.

In this activated sludge filtration device, during filtration operation (during biological reaction treatment), raw water is supplied to the biological reaction tank 31, and oxygen-containing gas such as air is diffused from the air diffuser 32 to perform biological treatment. And the biological treatment liquid is filtered by the filter unit 3
At 0, filtration is performed by the driving force based on the water head difference ΔH, and the treated water (filtered water) is introduced into the treated water tank 35 through the filtered water take-out collecting pipe 30A. That is, the water level in the treated water tank 35 is set lower than the water level in the biological reaction tank 31, and the head difference ΔH is used as a driving force to advance the filtration.

When filtration is continued for a long period of time, the filtration layer formed on the non-woven fabric surface of each filtration body of the filtration unit 30 is consolidated, filtration resistance increases, and the amount of filtered water decreases.
The filter body is regularly cleaned with gas. That is, by opening the valve V ₁ and performing aeration through the ventilation pipe 33, the filter layer on the surface of the nonwoven fabric of the filter body is washed and removed by sweeping the gas-liquid mixed flow. During the gas cleaning, air diffusion from the air diffuser 32 is usually stopped. By stopping the air diffusion during the gas cleaning in this way, the air diffuser 32 and the ventilation pipe 33 can share a blower or the like for supplying air.

The cleaning of each filter body of the filter body unit 30 may be carried out at the same time as the gas cleaning, or may be carried out independently of the gas cleaning.

In this cleaning, the supply of the raw water is stopped, the valve V ₂ is opened, and the water in the water supply tank 37 is used as the cleaning water under the natural flow through the cleaning water inflow collecting pipe 30B and the filter body unit 30. It is supplied to the inside (this cleaning water may be directly supplied from the treated water tank 35 by the water supply pump 36). A part of this washing water passes through the nonwoven fabric and flows out to the liquid side of the biological reaction tank 31, and in the process discharges suspended substances and the like in the filter body. The rest of the wash water is discharged from the filtered water extraction / collection pipe 30A, and in the process, turbid substances in the filter body are discharged to the treated water tank 35 side. When the discharged liquid needs to be treated again, the valve V ₄ is opened and the water supply pump 36 is opened.
Is returned to the raw water tank (not shown) or the biological reaction tank 31.

The activated sludge filtration device shown in FIG. 1 is an embodiment of the present invention, and the present invention is not limited to the illustrated device unless it exceeds the gist. The number of filters to be immersed in the biological reaction tank, the method of collecting filtered water, the arrangement of air diffusers and aeration tubes, etc. are optional.

[0045]

EXAMPLES The present invention will be described in more detail with reference to the following examples.

Examples 1 to 111, Comparative Example 1~ 6 Using the experimental device shown in FIG.
I investigated the relationship with qualitative.

This experimental apparatus is equipped with an anaerobic tank (effective volume 1
m ³ ) 41, an aerobic tank (effective volume 1.4 m ³ ) 42 and a precipitation tank (effective volume 0.27 m ³ ) 43, which is a nitrification / denitrification apparatus by a circulation method, A filter body 44 is dipped on the side, a diffuser pipe 45 for cleaning is provided at the lower part of the filter body 44, and a diffuser pipe 47 for aeration is provided on the other side through a partition wall 46.

The anaerobic tank 41 is provided with a stirrer 48.

49 is a synthetic sewage stock solution tank, P is a pump, B is a blower, and M is a motor.

In the aerobic tank 42, a filter body 44 is provided as shown in FIG.
Eight filter bodies having the configuration shown in FIG. The specifications of this filter are as follows.

Support: Vinyl chloride 50 cm × 50 cm × 1.5 cm Thickness spacer: DBS honeycomb net spacer Opening 3 mm Thickness 4 mm Nonwoven fabric: Unitika polyester nonwoven fabric (Product No. 2015)
7 WTD) Unit weight 15 g / m ² Separation particle size 100 μm Thickness 0.11 mm Filtration effective area of approximately 0.4 m ² per filter body The driving pressure for filtration is the water level of the aerobic tank 42 and the filtered water extraction pipe 50. The water level difference from the water level at the outlet was used, and the pressure was adjusted by the height of the take-out pipe 50.

As the raw water, the synthetic sewage stock solution having the composition shown in Table 1 was introduced through a pipe 51, and dilution water (tap water) was introduced through a pipe 52 to dilute the raw water continuously.

Table 2 shows the water quality (raw water quality) after the synthetic sewage dilution.
Introduced so that the load amount is as shown in Table 3.

[0054]

[Table 1]

[0055]

[Table 2]

[0056]

[Table 3]

The outflow water of the anaerobic tank 41 was fed to the aerobic tank 42 through the pipe 53, and a part of the liquid in the aerobic tank 42 was returned to the anaerobic tank 41 through the pipe 54.

Further, the liquid in the aerobic tank 42 was withdrawn through the pipe 55 as needed and fed to the settling tank 43, so that the raw water load was adjusted to be constant.

The supernatant water of the settling tank 43 is discharged from the system through the pipe 56. Further, a part of the separated sludge is returned to the anaerobic tank 41 through the pipe 57, and the rest is discharged out of the system through the pipe 58.

The intervals between the adjacent filter bodies and the flow velocity of the activated sludge mixed solution in the tank were changed to the values shown in Table 4, the treatment was carried out under the following conditions, and the average turbidity of the filtered water at that time was examined. The results are shown in Table 4.

MLSS of aerobic tank 42 = 5000 to 6500 mg / L Filtration water level difference = 270 mm Filtration flux: 2 m ³ / m ² / day In addition, the filter body 44 of the aeration pipe 47 is once every 3 hours for 3 minutes. Aeration was stopped, and gas was washed with air from the air diffuser 45. At this time, the removal of filtered water was stopped.

[0062]

[Table 4]

The following is clear from Table 4.

That is, when the spacing between the filter bodies is 4 mm, a dynamic filtration layer is formed on the non-woven fabric surface when the flow rate of the activated sludge mixture is 0.1 m / sec, and good filtered water is obtained, but 0.2 m / sec. No dynamic filtration layer was formed in the sample, resulting in filtered water with high turbidity.

On the other hand, the distance between the filters is 8 mm.
If so, a relatively good filtered water can be obtained up to 0.3 m / sec, and particularly, at intervals of 12 mm and 20 mm, a good dynamic filtration layer can be formed on the non-woven fabric surface up to a flow rate of the activated sludge mixed solution of 0.3 m / sec. A low turbidity filtered water is obtained which is formed. However, at a flow rate of 0.4 m / sec, a dynamic filtration layer was not formed and the filtered water had high turbidity.

Generally, the permissible turbidity of treated water is 150 or less,
Depending on the case, it is often set to 50 or less, and if the interval between the filter bodies is 8 mm or more, the flow rate is 0.05 to
It is apparent that filtered water having a turbidity of not more than a predetermined value can be obtained within a range of 0.3 m / sec, and particularly if this interval is 12 mm or more, better results can be obtained.

In the above experiment, when the distance between the filter bodies was set to 40 mm, the time-dependent change in the filtration flux and the time-dependent change in the turbidity of the filtered water (turbidity of the filter after 150 minutes of washing) were measured. This is shown in FIGS.

From FIGS. 8 and 9, the filtration fluxes 1.0, 1.5,
It can be seen that stable filtration at 2.0 m / day for 1000 hours or more is possible, and the turbidity of the filtered water is maintained well.

[0069]

As described in detail above, according to the activated sludge filtration device of the present invention, the activated sludge can be formed by forming a good activated sludge deposit layer on a plurality of filter bodies immersed in the biological reaction tank. Provided is a space-saving and energy-saving activated sludge filtration device capable of stably obtaining high-quality treated water by efficiently separating it.

[Brief description of drawings]

1A and 1B are views showing an example of an embodiment of a filter body suitable for the present invention, in which FIG. 1A is a partially cutaway front view, and FIG. 1B is taken along line BB in FIG. 1A. FIG.

2A and 2B are views showing another example of an embodiment of a filter body suitable for the present invention, in which FIG. 2A is a partially cutaway front view, and FIG. 2B is BB in FIG. 2A. It is sectional drawing which follows the line.

FIG. 3 is a cross-sectional view showing an example of the installation form of the filter body in the present invention.

4A and 4B are diagrams showing another example of the installation form of the filter body in the present invention, wherein FIG. 4A is a plan view and FIG. 4B is a side view.

FIG. 5 is a plan view showing still another example of the installation form of the filter body in the present invention.

FIG. 6 is a cross-sectional view showing an embodiment of the activated sludge filter device of the present invention.

FIG. 7 is a system diagram showing an experimental device used in Examples.

FIG. 8 is a graph showing the change over time in the filtration flux when the distance between the filter bodies is 40 mm.

FIG. 9 is a graph showing changes over time in the turbidity of filtered water when the distance between the filter bodies is 40 mm.

[Explanation of symbols]

1,1A filter 2,2A support 3,3A spacer 4,4A non-woven fabric 5,5A mounting frame 6 Frame material 30 Filter unit 30A Filtered water extraction collecting pipe 30B Wash water inflow collecting pipe 31 Bioreactor 32 Air diffuser 33 Ventilation pipe 34 Partition wall 35 treated water tank 36 Water pump 37 water tank 41 Anaerobic tank 42 aerobic tank 43 Settling tank 44 Filter 49 Synthetic sewage stock solution tank

─────────────────────────────────────────────────── ─── Continuation of front page (73) Patent holder 000006655 Nippon Steel Corporation 2-3-6 Otemachi, Chiyoda-ku, Tokyo (73) Patent holder 000005083 Hitachi Metals, Ltd. 1-chome, Shibaura, Minato-ku, Tokyo No. 2 (72) Inventor Hitoshi Daido 2-8-1, Nishi-Shinjuku, Shinjuku-ku, Tokyo Within the Tokyo Sewer Bureau (72) Inventor Eiji Aso 2-2-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo Within the Tokyo Sewer Bureau (72) Inventor Kazuo Suzuki 3-4, Nishi-Shinjuku, Shinjuku-ku, Tokyo Kurita Industry Co., Ltd. (72) Yoshihisa Kishine 3-4-7 Nishi-Shinjuku, Shinjuku-ku, Tokyo Kurita Industry Co., Ltd. (72) Inventor Kazuhisa Fukunaga 20-1 Shintomi, Futtsu City, Chiba Prefecture, Nippon Steel Co., Ltd. (72) Inventor Naoya Takahashi 20-1 Shintomi, Futtsu City, Chiba Prefecture, Nippon Steel Co., Ltd. (72) Invention Person Tetsuo Hasegawa 5200, Sankejiri, Kumagaya-shi, Saitama, Hitachi Metals Co., Ltd. (72) Inventor Mutaro Nagai 5200, Sankejiri, Kumagaya-shi, Saitama, Hitachi Metals Co., Ltd. (56) Proceedings of 34th Sewer Research Conference, Japan Sewer Association, June 25, 1997, 647-649 (58) Fields investigated (Int.Cl. ⁷ , DB name) C02F 3/02-3/10 C02F 3/12

Claims (2)

(57) [Claims] 1. A plurality of filter bodies provided with a filter cloth through which the activated sludge passes are immersed in the activated sludge mixed liquid in the biological reaction tank, and a deposit layer of the biological sludge is formed on the surface of the filter cloth. In the activated sludge filtering device for filtering the activated sludge mixed solution, the filter cloth is made of metal or polymer material, and has a separation particle size of 30.
Has an opening of ~ 1000 μm and a thickness of 0.1 to 1 mm
The non-woven fabric according to the present invention, wherein the distance between the filter bodies is 8 mm or more, and the cross flow velocity passing between the filter bodies is 0.05 to 0.3 m /
An activated sludge filtration device characterized by being sec. 2. The activated sludge filtration device according to claim 1, wherein the distance between the filters is 8 to 100 mm.