JPH10128358A - Biological treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waste water treatment apparatus wherein enough quality of treated water can be achieved even when filtration speed of a filter body is high in a waste water treatment apparatus wherein a filter body with a water-permeable sheet is arranged on the upper part of an aeration part. SOLUTION: A bag-like filter body 1(1A) is prepd. by inserting and laminating a water-permeable porous material 3 for holding an interval such as a sponge between two water-permeable sheets 2 and 2 such as nonwoven fabrics or woven fabrics with the min. reserved particle diameter or 30-1,000μm and sealing tightly the peripheral edges with these water-permeable sheets 2 and 2 to constitute it into a bag shape. A suction pipe 4 is pulled out upward from the top part of a filter body 1A and the apex part is curved downward into an approximately reverse U-shape and is communicated with a sedimentation basin 9. An immersion filter floor 6 consisting of a contact material is provided in a contact aeration tank 5. An aeration pipe 7 is arranged below the immersion filter material 6 and water in the tank is elevated while water in the tank is aerated by air bubbles generated from this aeration pipe 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biological treatment apparatus for treating wastewater, and more particularly to a water treatment apparatus in which water in a biological reaction tank such as an aeration tank or a contact aeration tank is taken out through a filter. Regarding improvement.

[0002]

2. Description of the Related Art Conventionally, as a method of separating activated sludge from water treated in an aeration tank or a contact aeration tank, a method of introducing treated water in an aeration tank to a sedimentation tank to precipitate and remove suspended substances in the treated water, A method of filtering treated water using an ultrafiltration membrane or the like is employed.

[0003] In the method of treating in a sedimentation tank, a sedimentation tank must be installed in addition to the aeration tank.
Not only a large installation area is required, but also construction costs are incurred, and the method using an ultrafiltration membrane has a problem that the apparatus becomes large and expensive.

[0004] To solve such problems, a low-cost filtration device having a simple structure without requiring a sedimentation tank is disclosed in
JP-A-185078 discloses a bag-shaped filter formed by sealing the periphery of a water-permeable sheet 2 stacked with a water-permeable porous material 3 interposed therebetween for maintaining a gap as shown in FIGS. 1
Is disposed above the air diffuser 7 in the aeration tank 5 and provided with a suction pipe 4 for extracting filtered water from the filter 1. Reference numeral 6 denotes a immersion filter bed.

In the biological treatment apparatus shown in FIGS. 2 to 4, the head difference between the treated water surface and the tip of the suction pipe 4 is relatively small,
By suctioning at a gentle speed with a low suction force, the aerated water penetrates the filter 1 and is drawn out of the aeration tank 5 by the suction pipe 4 with a head difference.

[0006] The suspended matter in the treated water is separated by filtration by the filter 1 having the water-permeable sheet 2, and a concentrated sludge cake layer is formed on the outer surface of the filter 1 when the filtration is continued. Then, fine particles in the treated water are captured by the filter action of the cake layer. If the head difference between the treated water surface and the tip of the suction pipe is large and the suction power is high, the thickness of the cake layer increases with time and the consolidation of the cake layer progresses, so that the filtration speed decreases rapidly. . However, by keeping the suction force low with a low head difference, the cake layer becomes fragile and repeatedly adheres to and separates from the filter body, maintaining a nearly constant thickness. Speed can be maintained.

[0007]

The above-mentioned JP-A-5-18
In the filtration device disclosed in Japanese Patent No. 5078, the cake layer on the surface of the water-permeable sheet 2 of the filter body 1 needs to be weak, and the filtration speed needs to be kept low. In addition, in the paragraph No. 0010 of the same publication, "the filtration speed is 1 to 10 m
Slow speed of about ³ / m ² days. "a. For this reason, the sedimentation tank can be omitted, but the amount of treated water decreases.

The present invention relates to a biological treatment apparatus in which a filter having a water-permeable sheet is disposed above an aeration section as disclosed in Japanese Patent Application Laid-Open No. 5-185078, even if the filtration speed of the filter is increased. It is an object of the present invention to provide a biological treatment apparatus capable of obtaining an amount of treated water and reducing a load on a subsequent solid-liquid separation unit.

[0009]

A biological treatment apparatus according to the present invention comprises a biological reaction tank, aeration means provided in the reaction tank, and a water-permeable sheet provided above the aeration means. And a solid-liquid separating means for solid-liquid separating water passing through the filter.

[0010] In such a biological treatment apparatus, since the filtered water from the filter is subjected to solid-liquid separation, a certain amount of SS (suspension material) is allowed to pass through as a water-permeable sheet of the filter. It becomes possible to adopt a coarse one. In addition, the aeration from the aeration means is strengthened so that the amount of cake adhering to the filter body is significantly reduced, and a certain amount of SS can be allowed to pass. By making the water-permeable sheet coarse or reducing the amount of cake adhering to the filter as described above, it is possible to increase the filtration speed of the filter.

The filtered water from the filter is separated into solid and liquid by a solid-liquid separation means such as a sedimentation separation device, a membrane separation device (for example, an ultrafiltration membrane separation device, a microfiltration device, etc.), a centrifugal separation device, and a filtration device. You. By returning the separated sludge into the biological treatment tank, the sludge concentration in the biological treatment tank can be maintained at a high value.

Since most of the filamentous bacteria are blocked by the water-permeable sheet of the filter, the filtered water of the filter does not contain a filamentous substance and is easily subjected to a solid-liquid separation treatment.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of a biological treatment apparatus according to an embodiment, and is similar to the apparatus shown in FIGS.
Is a bag-shaped filter, having a minimum retention particle diameter of 30 μm to 10 μm.
Two water-permeable sheets 2 and 2 such as a nonwoven fabric or a woven cloth of 00 μm are overlapped by inserting a water-permeable porous material 3 for maintaining a space such as a sponge therebetween, and the periphery of the water-permeable sheets 2 and 2 is It is sealed and formed into a bag shape.

Reference numeral 4 denotes a suction pipe, which is drawn upward from the upper portion in the filter 1A, and whose tip is bent downward in a substantially inverted U-shape and communicates with the sedimentation basin 9.

Reference numeral 5 denotes a contact aeration tank provided with an immersion filter bed 6 made of a contact material. A diffuser 7 is provided below the immersion filter bed 6.

The filter 1A is immersed and disposed above the aeration tube 7, and the suction tube 4 is drawn out of the aeration tank 5;
The difference between the height L ₁ of the process water in the aeration tank 5 and the height L ₂ of the front end of the suction tube 4, i.e., the water head difference L = L ₁ -L ₂ = 10c
The height of the suction pipe 4 is set so that the water head pressure becomes m to 100 cm. This head difference L indicates that the filtration speed of the filter 1A is 10 m ³ / m ² days or more, especially 20 to 100 m ³ /
Preferably, it is adjusted according to the concentration and properties of the sludge so as to be m ² days. .

Next, the operation of the biological treatment apparatus according to this embodiment will be described.

The raw water introduced into the contact aeration tank 5 is catalytically oxidized by the immersion filter bed 6. The water in the tank is
And rises while being aerated by bubbles generated from the air, and comes into contact with the filter 1A. It should be noted that bubbles are always ejected from the air diffuser 7. The water-permeable sheet 2 of the filter 1A,
The water that has permeated through 2 is drawn out of the aeration tank 5 by a suction head 4 due to a difference in head.

When the filtration is continued, the sludge cake layer tends to adhere to the outer surfaces of the water-permeable sheets 2 and 2. However, the water-permeable sheet 2 is coarse and the filter 1A is constantly in contact with the aerated bubbles. From there, only a very thin cake layer adheres to the surface of the water-permeable sheet 2. Therefore, the amount of permeated water of the water-permeable sheet 2 is significantly increased.

The filtered water from the filter 1A is supplied to the sedimentation basin 9
And subjected to a solid-liquid separation treatment, and the supernatant water is taken out of the system by overflow. Settled sludge is returned to pipe 1
Returned to the aeration tank 5 by 0.

It is particularly preferable that the aperture of the water-permeable sheet 2 of the filter 1A is 100 to 1000 μm. When the opening is increased in this way, the activated sludge is separated by 8
It is about 0 to 90%, and the remaining 10 to 20% is sent to the sedimentation basin 9.

As a result of various experiments, in this biological treatment apparatus, the amount of permeated water is 10 to 5 even when L = 10 cm.
0 m ³ / m ² days, and if L = 20 cm, 20 to 1
It was recognized that the number of times could be significantly increased to 00 m ³ / m ² days as compared with the conventional method (FIGS. 2 to 4). In addition, the SS concentration in the filtered water of the filter was about 100 to 1000 mg / liter.

[0023]

According to the present invention, in a biological treatment apparatus in which a filter is immersed and disposed above aeration means in a biological treatment tank such as an aeration tank or a contact aeration tank, the filtration speed is increased and the efficiency is improved. Wastewater treatment can be performed, and the amount of treated water can be kept high. In addition, since most of the sludge can be separated by the filter, the load on the subsequent solid-liquid separation means can be significantly reduced, and the size of the solid-liquid separation means can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of a biological treatment apparatus according to an embodiment.

FIG. 2 is an explanatory view of a filtration device for an aeration tank according to a conventional example.

FIG. 3 is a perspective view, partially cut away, of a filter of the apparatus of FIG. 2;

FIG. 4 is a longitudinal sectional side view of a filter.

[Explanation of symbols]

 1, 1A filter body 2 water-permeable sheet 3 water-permeable porous material 4 suction pipe 5 aeration tank 7 diffuser pipe 9 sedimentation basin 10 return pipe

 ──────────────────────────────────────────────────続 き Continuation of the front page (71) Applicant 000006655 Nippon Steel Corporation 2-6-3 Otemachi, Chiyoda-ku, Tokyo (71) Applicant 000005083 Hitachi Metals, Ltd. 2-1-1 Marunouchi, Chiyoda-ku, Tokyo No. 2 (72) Inventor Hitoshi Daido 2-8-1, Nishi-Shinjuku, Shinjuku-ku, Tokyo Inside the Tokyo Metropolitan Sewerage Bureau (72) Inventor Noriyuki Tajima 2-1-1, Nishishinjuku, Shinjuku-ku, Tokyo Inside Tokyo Metropolitan Sewerage Bureau (72 Inventor Tetsuro Fukase 3-4-7 Nishi-Shinjuku, Shinjuku-ku, Tokyo Kurita Kogyo Co., Ltd. (72) Inventor Kunihiro Iwasaki 3-4-7 Nishi-Shinjuku, Shinjuku-ku, Tokyo Kurita Kogyo Co., Ltd. (72) Invention Naoya Takahashi 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Corporation In-house (72) Inventor Mitsuo Kondo 2-6-1 Otemachi, Chiyoda-ku, Tokyo New Japan-made In stock 會社 (72) inventor Tetsuo Hasegawa Kumagaya, Saitama Prefecture Mikajiri 5200 address Hitachi Metals shares in the company (72) inventor Mutsuo Nagai Kumagaya, Saitama Prefecture Mikajiri 5200 address Hitachi Metals shares in the company

Claims (1)

[Claims] 1. A biological reaction tank, aeration means provided in the reaction tank, a filter provided on top of the aeration means for filtering water in the reaction tank by a water-permeable sheet, and the filtration A biological treatment apparatus comprising: solid-liquid separation means for performing solid-liquid separation of water that has passed through the body.