JPH10314792A - Sewage treatment equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a batch type activated sludge treating device which can maintain activated sludge at high concentration. SOLUTION: In the batch type waste water treating device in which a biological reaction tank 2 which is partitioned into an anaerobic tank 4 for denitrifying raw water, an aerobic tank 5 for nitrifying denitrified liquid, and an aeration tank 6 for aerating nitrified liquid is provided and after settling sludge, supernatant water is discharged, a filter member 11 having a filter supporting membrane is disposed in a partition wall 7a separating the tank 4 and tank 5 and in a partition wall 7b separating the tank 5 and tank 6, and a filter unit 10 having a filter supporting membrane is disposed in the tank 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for biologically treating sewage by a batch activated sludge method, and more particularly to an apparatus for sewage treatment in which a filtration unit is immersed in a biological reaction tank.

[0002]

2. Description of the Related Art In a sewage treatment apparatus using activated sludge that decomposes organic matter in wastewater by a biological reaction, first, microorganisms are eaten by organic matter in the wastewater in an aeration tank in the presence of air.
The organic matter is removed from the sewage, and then the organic matter is eaten in the sedimentation basin to sediment the vegetated microorganisms as sludge and separate from the water, and the supernatant water is collected and sent to the next step, while the sedimentation basin The settled sludge is collected and sent to, for example, a dehydration step.

As this activated sludge method, there is a continuous type, but a batch type activated sludge method which is easier to maintain and manage than the continuous type and is suitable for small-scale wastewater treatment is also used. . The batch type activated sludge method is a treatment method in which each step of inflow, aeration, and settling is performed repeatedly as one cycle in a single treatment tank. For example, an anaerobic tank (denitrification tank),
In this method, nitrification and denitrification are performed in a single treatment tank (biological reaction tank) partitioned into an aerobic tank (nitrification tank) and an aeration tank (denitrification tank).

[0004]

In the above-mentioned batch type activated sludge treatment apparatus using the activated sludge process, it is necessary to perform appropriate sludge extraction control in order to maintain stable and high treatment performance. Alternatively, sludge is extracted every cycle. However, in the conventional device,
Inability to cope with changes in sludge generation rate due to inflow load fluctuations,
Therefore, MLSS which is an important index of sludge treatment function
There is a problem that the concentration of (sludge mixed liquid suspended solids) decreases and the treatment performance deteriorates.

[0005] In order to perform activated sludge treatment of wastewater with high efficiency, a carrier for immobilizing the activated sludge (fine particles of earth and sand, activated carbon particles or porous organic polymer particles) is charged into an aeration tank of a biological treatment apparatus. It has also been practiced to make these particles flow in an aeration tank by aeration and to attach activated sludge to the particles, thereby maintaining a high concentration of activated sludge. However, in the sludge treatment apparatus based on the carrier charging method, it takes a long time for the activated sludge to stably adhere to the carrier, and the MLSS concentration cannot be maintained at a high level, thereby deteriorating the treatment performance. .

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a sewage treatment apparatus capable of performing batch activated sludge treatment while maintaining activated sludge at a high concentration. Another object of the present invention is to provide a sewage treatment apparatus capable of performing batch activated sludge treatment using a microorganism carrier while maintaining activated sludge at a high concentration.

[0007]

In order to achieve the above object, according to a first aspect of the present invention, there is provided a treatment tank for inflowing wastewater for biological treatment, and a treatment tank for discharging sludge after settling sludge. A sedimentation tank, and the treatment tank is an anaerobic tank that is divided into an anaerobic tank that performs denitrification, an aerobic tank that performs nitrification of the denitrification liquid, and an aeration tank that aerates the nitrification liquid. Along with disposing a filtration member having a filtration support membrane in a partition between the aerobic tank and between the aerobic tank and the aeration tank, and a filter member having a filtration support membrane in the aeration tank, The technical means that was adopted. In the first invention, the filtration support membrane is desirably made of a metal nonwoven fabric or a nonwoven fabric.

[0008] In order to achieve the above object, the second invention has a treatment tank for inflowing sewage for biological treatment, and a sedimentation tank for discharging sludge after discharging sludge. The treatment tank is an anaerobic tank that performs denitrification, an aerobic tank that performs nitrification of the denitrification liquid, and a microorganism carrier that is charged with the aerobic tank that is divided into an aeration tank that aerates the nitrification liquid. A filter member having a filtration support membrane is disposed on a partition wall between the aerobic tank and between the aerobic tank and the aeration tank, and a filtration member having a filtration membrane is immersed in the aeration tank. , The technical means of adopting. In the second invention, the filtration support membrane is preferably made of a metal nonwoven fabric or a nonwoven fabric.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic sectional view of a sewage treatment apparatus according to one embodiment of the present invention. In the figure, 1 is a raw water tank for storing sewage (sewage, wastewater, etc.), 2 is a biological reaction tank for treating the sewage fed from the raw water tank 1, and 3 is a separator for separating biologically treated sewage from sludge. It is a precipitation tank for separating into liquids. The biological reaction tank 2 is an anaerobic tank 4 for denitrifying sewage (reducing oxidized nitrogen to nitrogen gas by an oxidation reaction of organic matter in sewage) and nitrifying the denitrification liquid (to convert ammoniacal nitrogen to nitrous acid). Aerobic tank 5 for oxidizing to nitric acid or nitric acid) and aeration tank 6 for aerating the nitrification liquid (treating organic substances not treated in the previous step and activating sludge). It is partitioned. The filtering member 11 is immersed in the partition wall 7a that partitions the anaerobic tank 4 and the aerobic tank 5 and the partition wall 7b that partitions the aerobic tank 5 and the aeration tank 6. Inside the aeration tank 6, a filtration unit 10 and a diffuser tube 8 are immersed.

FIG. 2 is an AA sectional view of the aeration tank shown in FIG. The aeration tank 6 is divided into two by a partition 9 provided at the center thereof, and an upper communication part 6a and a lower communication part 6b are provided at an upper part and a lower part of the partition 9 so that water in the two divisions can communicate with each other. Are formed. In the right section of the aeration tank 6, a filtration unit 10 is disposed. The discharge end of the water collecting pipe 20 communicating with the filtration unit 10 falls into the settling tank 3, and the air diffusion pipe 8 connected to the blower 21 is provided in the left section. Are located. Here, by setting the water level of the sedimentation tank 3 lower than the water level of the sedimentation tank 6, a negative pressure due to the head difference always acts inside the filtration unit 10 due to the siphon effect of the water collecting pipe 20.

FIG. 3 is a plan view in which a part of a filtration member constituting the filtration unit 10 is cut away, and FIG. 4 is a sectional view taken along line BB of FIG. In both figures, reference numeral 11 denotes a filter member, which includes a filter plate 12 (a spacing member) and spacer members 13 on both sides thereof.
Support membrane 1 fixed by a frame-shaped holding plate 14
And 5. On the surface of the filter plate 12, water collecting grooves 16 are formed vertically and horizontally. At the uppermost part of the filter plate 12, a horizontal hole 17 communicating with the water collecting grooves on both sides is formed, and a screw hole 18 is provided from the end face of the filter plate 12 to the horizontal hole 17, and the filtered water is inserted into the screw hole 18. A suction tube 19 for pulling out the screw is screwed. The suction pipe 19 is connected to the water collecting pipe 20, and the water filtered by the filtration member 11 is conveyed to the precipitation tank 3 via the water collecting pipe 20.

As the filtration support membrane 15, a non-woven fabric or a woven fabric made of a thermoplastic resin such as polyester resin or polypropylene can be used. In order to capture sludge efficiently, a nonwoven fabric having a flat surface and easily forming a bridge on the surface is preferable, but a woven fabric having a raised surface can also be used effectively.
If the above nonwoven fabric is too thick, sludge accumulates in the filtration membrane and clogging is likely to occur. On the other hand, if it is too thin, the mechanical strength decreases, so it is desirable that the nonwoven fabric has a thickness of 0.1 to 1 mm. The aperture of the filtration membrane preferably has a separation particle size of 10 μm or more (preferably 10 to 100 μm).

As the filtration support membrane 15, for example, a stainless steel plain woven wire mesh and a 10-20 μm stainless steel wire or a stainless steel fiber
m, cut into short fibers, and the density ratio is 90
%, And a metal nonwoven fabric formed by applying a load of 5 to 50 g / cm ² and sintering in a hydrogen atmosphere at 1020 ° C. for 30 minutes may be used.
Since the metal nonwoven fabric has the crossed portions of the short fibers fixed by sintering, a strong nonwoven fabric can be obtained. Further, since the metal nonwoven fabric is supported by a wire net, the filtration membrane has high strength. Therefore, when a filtration support membrane formed of a metal nonwoven fabric is used, the spacer member can be omitted.

The above metal nonwoven fabric has a thickness of 0.2 to 4 m.
m, the cross-sectional direction has the same textile structure as the surface direction, and the size of the opening in the surface direction is larger than 20 μm. If the thickness of the filtration membrane is too thick, sludge accumulates in the filtration membrane and clogging is likely to occur. On the other hand, if the thickness is too small, the mechanical strength decreases, so that the thickness is desirably about 0.2 to 4 mm. The size of the filter membrane is 2
It is desirable that the thickness be 0 μm or more (preferably 20 to 100 μm).

According to the sludge treatment apparatus having the above configuration, sewage is treated as follows. Raw water flowing from the raw water tank 1 into the biological reaction tank 2 is denitrified in the anaerobic tank 4, the denitrification liquid is nitrified in the aerobic tank 5, and the nitrification liquid is aerated in the aeration tank 6.
That is, the nitrification liquid that has flowed into the aeration tank 6 is aerated by the air diffuser 8 to become a mixed water of activated sludge fine particles and water. When the mixed water reaches the section in which the filtration unit 10 is immersed, the mixed water becomes an ascending flow in the left section by air bubbling from the air diffuser 8 and passes through the upper communication portion 6a of the partition 9 to the left section. The water then flows downward and circulates through the lower communication portion 6b so as to return to the left section again. During this circulation, the activated sludge fine particles in the mixed water are captured by the filtration unit 10 by the filtration unit 10 immersed in the right compartment.

That is, initially, the activated sludge fine particles pass through the opening of the filtration support membrane, but gradually adhere to the surface of the filtration support membrane and close the opening, and the cake layer (not shown) is formed by the grown sludge fine particles. Are formed, and the activated sludge fine particles in the water are captured by the filtering action of the cake layer made of the activated sludge fine particles, and the filtering action proceeds. On the other hand, the permeated water is sent to the sedimentation tank 3 via the water collecting pipe 20 provided in the filtration unit 10. The driving force for sending water from the filtration unit 10 to the settling tank 3 via the water collecting pipe 8 is the siphon effect described above, and no special power source is required. Filtration unit 1
Within 0, suction filtration is performed due to the pressure difference due to the head difference, but by setting this pressure difference to 100 mm with a water column, a permeation flux of about 1 m / day can be obtained.

The filtering member 11 is also provided on a partition wall 7a for partitioning the anaerobic tank 4 and the aerobic tank 5 of the biological reaction tank 2 and a partition wall 7b for partitioning between the aerobic tank 5 and the aeration tank 6. Since they are arranged, the same filtering action as described above is performed in these partition portions 7a and 7b. Therefore, according to the above-mentioned sewage treatment apparatus, the concentration of activated sludge (MLSS concentration) in each tank can be greatly increased as compared with the conventional one, and since there is a self-nitrification effect, the excess sludge is reduced to about half of the conventional one. Can be. Therefore, the operation time is only about half of the conventional case, and the volume of the processing tank is about half of the conventional case, so that the installation space can be reduced.

FIG. 5 is a schematic sectional view of a sewage treatment apparatus according to another embodiment of the present invention, and the same parts as those in FIG. 1 are denoted by the same reference numerals. This sewage treatment apparatus has a raw water tank 1 storing sewage, a biological reaction tank 2 for treating sewage, and a sedimentation tank 3 for separating treated sewage into sludge and a separated liquid. A filtering member 11 is disposed on a partition wall 7a for partitioning the tank 4 and the aerobic tank 5 and a partition wall 7b for partitioning the aerobic tank 5 and the aeration tank 6, and a filtration unit 10 is further disposed inside the aeration tank 6. At the same time, the fixed carrier 30 for activated sludge is put into the aeration tank 6. According to this device, the immobilized carrier particles flow in the aeration tank by aeration, and the activated sludge adheres to the carrier particles, so that the activated sludge can be maintained at a higher concentration. In addition, since nitrifying bacteria proliferate and can be stably processed, the operation time can be reduced. Further, the removal rates of nitrogen and phosphorus can be increased.

[0019]

【Example】

(Example 1) Sewage treatment was performed using the apparatus shown in FIGS. Raw water is BOD180mg / L, SS1
Using 30 mg / L of sewage, the capacity of the raw water tank 1 is 1 m ³
The effective capacity of each of the aerobic tank 4, the anaerobic tank 5 and the aeration tank 6 is set to 2 m ^3, and a filtration unit having a filter member having a side surface area of 40 mm × 40 mm is immersed in the partition walls 7 a and 7 b and the aeration tank 6. Then, batch activated sludge treatment was performed on a scale of 1 m ³ / Hr. The filtration module is provided with a polyester resin non-woven fabric (amount per unit area: 30 g / m ² , fiber diameter: 18 μm, separation particle diameter: 50 μm, thickness: 0.2 mm) on the surface of a spacing member formed of an ABS resin via a corrugated spacer. The fixed one (No. 1 member) was used. Further, as a filtration member, a surface having a diameter of 20 μ
SUS316L fiber with a length of 5 mm
Metallic non-woven fabric created by spraying and sintering on a 316L hand-woven wire mesh (thickness: 2 mm, opening size in the surface direction: 50 μm)
An experiment was performed under the same conditions as described above, using a material (No. 2 member) to which was fixed. For comparison, an experiment was performed under the same conditions as above except that the filtration member was removed from the biological reaction tank 2. As a result of the above experiment, when the filtration module was not used, the MLSS concentration in each tank was about 2,000 mg.
/ L, processing time is 8 hours, and BOD 25m
g / L, SS 30 mg / L. On the other hand, the filter member of the present invention (No. 1 member, N
o. When (2 members) were used, the MLSS concentration in each tank reached about 18,000 mg / L, the treatment time was reduced to 6 hours, and the treated water quality was improved to BOD 5 mg / L and SS 10 mg / L.

(Example 2) Sewage treatment was performed using the apparatus shown in FIG. 5 under the following conditions. Sewage treatment was performed under the same conditions as in Example 1 except that zeolite having a particle size of 1 to 2 mm was charged as a microorganism carrier into the aeration tank. For comparison, an experiment was performed under the same conditions as above except that the filtration module was removed from each of the biological reaction tanks. As a result of the above experiment, when the filtration module was not used, the MLSS concentration in each tank was about 2,000 mg / L, the treatment time was 8 Hr, and the quality of the treated water was BOD 25 mg / L, SS 30 mg / L, The P removal rate was only 70%, and the N removal rate was only 70%. On the other hand, according to the apparatus of the present invention, M
The LSS concentration is about 18,000 mg / L, the treatment time is reduced to 6 hours, and the treated water quality is BOD 5 mg / L.
L, SS10mg / L, P removal rate 80%, N removal rate 90
% Was significantly improved.

[0021]

As described above, according to the first aspect, the MLSS concentration in the biological reaction tank can be maintained at a high level, and the processing time can be greatly reduced. According to the second invention, the MLS in the biological reaction tank
The effect is obtained that the S concentration can be maintained at a high concentration and the removal rates of N and P can be increased.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a sewage treatment apparatus according to one embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a partially cutaway plan view of a filtration module according to the present invention.

FIG. 4 is a sectional view taken along line BB of FIG. 3;

FIG. 5 is a schematic sectional view of a sewage treatment apparatus according to another embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 1 raw water tank, 2 biological reaction tank, 4 anaerobic tank, 5 aerobic tank, 6 aeration tank, 7a, 7b partition, 10 filtration unit, 11 filtration member, 12 interval holding member, 13 spacer member, 15 filtration support membrane, 30 Microbial carrier

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C02F 3/30 C02F 3/30 B (71) Applicant 000001063 Kurita Kogyo Co., Ltd. 3- 4-7 Nishishinjuku, Shinjuku-ku, Tokyo ( 71) Applicant 000006655 Nippon Steel Corporation 2-6-3, Otemachi, Chiyoda-ku, Tokyo Person Noriyuki Tajima 2-1-1 Nishi Shinjuku, Shinjuku-ku, Tokyo Tokyo Metropolitan Government Sewerage Bureau 5200 No. 3 Ichiga-shi, Ichiba, Kumagaya Plant, Hitachi Metals Co., Ltd. (72) Inventor Kazuo Suzuki 3-7, Nishi-Shinjuku, Shinjuku, Tokyo Yoshihisa Kishine Kurita Industries Co., Ltd., 3-4-7 Nishi Shinjuku, Shinjuku-ku, Tokyo (72) Inventor Kazuhisa Fukunaga 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Corporation In-house (72) Inventor Morio Sakata Tokyo 2-6-3 Otemachi, Chiyoda-ku, Tokyo Nippon Steel Corporation

Claims (6)

[Claims] 1. A treatment tank for inflowing wastewater for biological treatment, and a sedimentation tank for discharging sludge after sedimentation of sludge, wherein the treatment tank has an anaerobic tank for denitrification and a denitrification tank. In a sewage treatment apparatus divided into an aerobic tank for nitrifying a liquid and an aeration tank for aerating a nitrifying liquid, a partition for partitioning between an anaerobic tank and an aerobic tank and between an aerobic tank and an aeration tank A sewage treatment apparatus, wherein a filtration member having a filtration support membrane is disposed in a section, and a filtration member having a filtration support membrane is immersed in an aeration tank. 2. The sewage treatment apparatus according to claim 1, wherein the filtration support membrane is made of a metal nonwoven fabric. 3. The sewage treatment apparatus according to claim 1, wherein the filtration support membrane is made of a nonwoven fabric. 4. A treatment tank for inflowing sewage for biological treatment, and a sedimentation tank for discharging sludge after sedimentation. The treatment tank is provided with an anaerobic tank for denitrification and a denitrification tank. An aerobic tank for performing nitrification of the liquid and a microorganism carrier are charged, and in a sewage treatment apparatus partitioned into an aeration tank for aerating the nitrifying liquid, the anaerobic tank and the aerobic tank and between the aerobic tank and the aeration tank. A sewage treatment apparatus characterized in that a filtration member having a filtration support membrane is disposed in a wall partition section between the filtration members, and a filtration member having a filtration support membrane is immersed in an aeration tank. 5. The sewage treatment apparatus according to claim 4, wherein the filtration support membrane is made of a metal nonwoven fabric. 6. The sewage treatment apparatus according to claim 4, wherein the filtration support membrane is made of a nonwoven fabric.