JP3237639B2 - Biological filtration tank for sewage purification tank - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biological filtration tank for a sewage purification tank which employs a biological filtration method for performing wastewater treatment.

[0002]

2. Description of the Related Art A conventional sewage treatment tank will be described with reference to FIG. The sewage purification tank 28 is divided into anaerobic filter bed tanks 1 and 3 by partition walls, anaerobic filter bed tanks 2 and 7, biological filtration tanks 10, and
The treatment water tank 12 and the disinfecting tank 13 are partitioned, and the contact material 4 is provided in each of the first chamber 3 and the second chamber 7 of the anaerobic filter bed tank. In addition, the biological filtration tank 10 is provided with a carrier bed filled with the granular carriers 16 so that biological filtration can be performed.

[0003] The water to be treated 1 enters the first chamber 3 of the anaerobic filter bed from the inflow port 2 and then flows to the second chamber 7 of the anaerobic filter bed, the biological filtration tank 10, the treated water tank 12, and the disinfection tank 13 in that order. It is supposed to. In the biological filtration tank 10, the granular carrier 1
Microorganisms 6 are attached to 6 and simultaneously perform biological decomposition of organic matter in wastewater and physical filtration of SS. Therefore, when the sewage purification tank 28 is continuously operated, the biological filtration tank 10 is gradually closed by the SS. In order to remove the SS from the biological filtration tank 10, it is necessary to temporarily suspend the normal operation and to backwash the granular carrier 16 by causing the treated water in the treated water tank 12 to flow backward by the transfer pump 26 or the like.

[0004]

However, in order to carry out back washing of the granular carrier 16, a large amount of washing water is applied to the treatment tank 1.
Therefore, a high-power pump is required for good backwashing. Therefore, an object of the present invention is to provide a biological filtration tank for a sewage purification tank that reduces the amount of washing water (water stored in a treated water tank) used for backwashing the granular carrier 16 and that requires a small amount of power. And

[0005]

The biological filtration tank for a sewage purification tank according to the present invention comprises, for example, an anaerobic filter bed tank in a first chamber 3 and a second chamber 3.
The contact material 4 is divided into chambers 7, each of which is provided with a contact material 4, and a biological filtration tank 10 is provided with upper and lower perforated plates. 30
The air diffusion members 11 and 20 are provided below the upper and lower carrier beds, respectively, and are used for the sewage purification tank 28.
Normally, the boundary 31 between the upper carrier bed 29 and the lower carrier bed 30 and the upper part of the first chamber 3 of the anaerobic filter bed are connected by a washing drainage pipe 21 having a transfer pump 26. In the present invention, the capacity of the treated water tank 12 at a portion higher than the height of the boundary 31 between the upper carrier bed 29 and the lower carrier bed 30 is set to be larger than the capacity of the lower carrier bed 30.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The transfer pump 26 mentioned here may be an air lift pump or a submersible pump as long as it can transfer water. The upper carrier bed 29 and the lower carrier bed 30
The capacity of the treatment water tank 12 above the height of the boundary portion 31 indicates the capacity between the position corresponding to the height of the boundary portion 31 in the treatment water tank 12 and the outlet 15.

The air diffusing members 11 and 20 provided below the upper carrier bed 29 and the lower carrier bed 30, respectively, feed air so that the air diffusing members 11 corresponding to the upper carrier bed 29 promote biological decomposition. On the other hand, the air diffusing member 20 corresponding to the lower carrier bed 30 does not operate during normal operation but only operates during backwashing.

In the present invention, the carrier bed installed in the biological filtration tank 10 is divided into two stages, so that most of the SS can be collected in the lower carrier bed 30, and the lower carrier bed 30 is mainly inverted. Means for avoiding blockage by washing is used.
Then, by setting the capacity of the treatment water tank above the boundary portion 31 to be larger than the capacity of the lower carrier bed 30, the treatment water in the lower carrier bed 30 can be completely replaced, and sufficient washing can be performed. It is.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view and a sectional view of a sewage purification tank of the present invention. The water 1 to be treated is supplied from the inlet 2 and enters the first chamber 3 of the anaerobic filter tank, where coarse solids are removed by the contact material 4 and at the same time, anaerobic decomposition and denitrification are carried out by the returned treated water. It is. The space above the contact member 4 is preferably provided with a fixed position of the contact member at a middle position or less of the height of the first anaerobic filter tank 3 in order to provide a flow rate adjusting function for absorbing inflow fluctuations. The returned treated water means treated water returned from the treated water tank 12 to the first anaerobic filter tank 1 chamber 3 by the anaerobic filter tank circulation pipe 32.

The effluent 8 from the first anaerobic filter tank 1 chamber whose flow rate has been adjusted by the first anaerobic filter tank 3 is transferred by the transfer pump 6 to the second anaerobic filter tank 2. Here, the decomposition of the organic matter which could not be decomposed in the first anaerobic filter tank 1 and the further denitrification are performed, and then the effluent 9 from the second anaerobic filter tank 2 flows to the upper part of the biological filter 10 under natural flow. Be transported.

The biological filtration tank 10 has two upper and lower carrier beds filled with granular carriers 16 to which aerobic microorganisms are adhered in spaces separated by perforated plates. A diffuser members 11 and 20 are provided below each carrier bed, and the diffuser members 11 below the upper carrier bed 29 exhaust air required for aerobic microorganisms to perform biological treatment. ing. Therefore, in the upper carrier bed 29, although the decomposition of organic substances and the nitrification of ammonia are performed, the capture of SS is rarely performed by bubbling due to air discharge (the granular carrier swings due to air bubbles).

On the other hand, the diffusing member 20 below the lower carrier bed 30 is
Since air is ejected only at the time of backwashing, SS can be sufficiently captured without swinging of the granular carrier 16 during normal operation. Furthermore, in the lower carrier bed 30, even if there is no air supply from the air diffuser 20 below the lower carrier bed 30, the upper carrier bed 29
Since the treated water flowing down from the column contains air (dissolved oxygen) sufficiently, it is possible to decompose organic substances and to nitrify ammonia.

[0013] The water to be treated by the above treatment steps is
Since organic matter, SS, and nitrogen are sufficiently removed, the treated water becomes transparent and highly treated water. The treated water is transferred to the treated water tank 12, sterilized in the disinfecting tank 13, and discharged from the outlet 15 as treated water 14.

Next, the operation during the normal operation and during the backwash will be described with reference to FIG. FIG. 2A shows a processing state during normal operation. As described above, the biological filtration tank 10 is provided with the upper carrier bed 29 and the lower carrier bed 30, and the air diffusion members 11 and 20 are provided below each of them. At the boundary 31 between the upper carrier bed 29 and the lower carrier bed 30, a washing drainage pipe 21 connected to the upper part of the first anaerobic filter tank 3 is provided. The washing drainage pipe 21 has a transfer pump 26 for pulling water out of the biological filtration tank 10, and the biological filtration tank 10 and the treatment water tank 12 are communicated by an opening 22 provided at a lower part. .

Water 23 to be treated from the anaerobic filter tank second chamber 7
Is transferred to the upper carrier bed 29 installed in the biological filtration tank 10. The granular carrier 16 of the upper carrier bed 29 is
Is filled to the extent that it swings with air bubbles discharged from the upper carrier bed 29 so that the air bubbles spread over the entire upper carrier bed 29. Aerobic microorganisms are adhered to the granular carrier 16 and air (actually, oxygen in the air) from the diffusing member 11.
As a result, the biological treatment (BOD decomposition and nitrification) of the water 23 proceeds. However, the capture of SS is performed by the air diffusing member 11.
It cannot be completely performed by air discharge from the air.

Therefore, the SS is sufficiently captured by the lower carrier bed 30 and the biological treatment (BOD) of the water 23 to be treated is performed.
Decomposition and nitrification). As described above, the lower carrier bed 3
The air diffusing member 20 provided at the lower portion of the lower carrier bed 30 in normal operation is used to discharge air only during backwashing.
6 is stationary. Therefore, sufficient SS can be captured. The biological treatment (BOD decomposition and nitrification) of the treated water 23 proceeds because dissolved oxygen is carried over from the upper carrier bed 29.

FIG. 2B is a cross-sectional view of the vicinity of the biological filtration tank for explaining the situation at the time of back washing. When the operation shifts from the normal operation to the backwash operation, the air diffusion is started from the air diffusion member 20 below the lower carrier bed 30. The granular carrier 16 packed in the lower carrier bed 30
Oscillates due to aeration and separates the SS between the granular carriers 16. At this time, for example, the washing wastewater containing SS is drawn into the first anaerobic filter bed tank 3 by the washing wastewater discharge pipe 21 having one end connected to the boundary 31 between the upper carrier bed 29 and the lower carrier bed 30. In order to extract the washing wastewater, an air lift type pump is preferable in structure, but other submersible pumps and the like can be used.

The washing wastewater drawn out from the washing wastewater discharge pipe 21 includes SS contained in the lower carrier bed 30 and SS of the upper carrier bed 29 as the water level in the biological filtration tank 10 decreases.
The amount of SS is, of course, the amount of S discharged from lower carrier bed 30.
S is larger, and backwashing of the lower carrier bed 30 is important in the present invention. At the time of back washing, since the air diffusing member 20 under the lower carrier bed 30 diffuses air, the SS is easily dispersed throughout the lower carrier bed 30, and in order to efficiently remove (discharge) SS, An extrusion flow from below the lower carrier bed 30 is preferred. In order to sufficiently remove (discharge) SS,
Processing water more than the capacity of the lower carrier bed 30 is required.

In the present invention, since the treated water having a volume equal to or larger than the capacity of the lower carrier bed 30 is secured in the treated water tank 12, it is possible to sufficiently remove (discharge) SS. Furthermore, since the treated water more than the capacity of the lower carrier bed 30 is secured above the boundary 31 to which the washing drainage pipe 21 for pulling out the washing wastewater is connected, the water level of the biological filtration tank 10 is reduced. Sufficient backwashing can be performed without lowering from the boundary. Since the pump has cleaning water above the boundary where the cleaning drainage is drawn out, it effectively uses potential energy and requires only a small amount of power.

FIG. 3 shows an embodiment of the present invention in which the treatment water tank 12 is made more compact. In this case, the biological filtration tank 10 and the treatment water tank 12 are communicated with each other through the lower opening 22 as in FIG. 2, but the capacity of the treatment water tank 12 corresponding to a position below the boundary 31 is greatly increased. It has been reduced.

[0021]

As described above, in the biological filtration tank for a sewage purification tank according to the present invention, the amount of washing water in the biological filtration tank can be reduced, and sufficient SS can be discharged. In addition, the size of the treated water tank can be reduced, and the entire sewage treatment tank can be made compact. Also, the pump used at the time of backwashing can be handled with a small required power.

[Brief description of the drawings]

FIG. 1 is a drawing for explaining a biological filtration tank for a sewage purification tank according to the present invention, wherein (a) is a plan view and (b) is a cross-sectional view along AA.

FIGS. 2A and 2B are cross-sectional views of a biological filtration tank for a sewage purification tank for explaining an embodiment of the present invention, wherein FIG.
Indicates a backwash operation.

FIG. 3 is a sectional view of a biological filtration tank for a sewage purification tank showing another embodiment according to the present invention.

FIG. 4 is a cross-sectional view of a conventionally used sewage purification tank.

[Explanation of symbols]

1. 1. Water to be treated Inlet 3. Anaerobic filter bed tank 1st room 4. Contact material 5. Volume part 6. Transfer pump
7. 7. Anaerobic filter tank 2nd room 8. Anaerobic filter bed tank 1st room effluent 9. Anaerobic filter tank second room effluent Biological filtration tank 11. Diffuser member 12. Treated water tank 13. Disinfection tank 14. Treated water 15. Outlet 16. Granular carrier 17. Perforated plate 18. Perforated plate
19. Perforated plate 20. Diffuser member 21. Wash drainage pipe 22. Opening 23. Water to be treated 24. Wash water 25. Treated water 26. Transfer pump 27.
Wash drainage 28. Sewage septic tank 29. Upper carrier bed
30. Lower carrier bed 31. Border part 32. Anaerobic filter tank circulation pipe

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-337481 (JP, A) JP-A-5-309382 (JP, A) JP-A-5-138183 (JP, A) JP-A-5-138183 269482 (JP, A) JP-A-5-212390 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C02F 3/00

Claims (1)

(57) [Claims] 1. A carrier bed having upper and lower perforated plates and having granular carriers filled in a space partitioned by the perforated plates is arranged in two stages as an upper carrier bed and a lower carrier bed, and is provided below the upper and lower carrier beds. A biological filtration tank for a sewage purification tank wherein a diffusion member is provided, and the capacity of a treatment water tank in a portion above the height of the boundary between the upper carrier bed and the lower carrier bed is larger than the capacity of the lower carrier bed.