JPS6261699A - Fluidized bed type waste water treatment apparatus - Google Patents

Abstract

PURPOSE:To facilitate maintenance control, by forming an aerobic zone and an anaerobic zone in a treatment tank to perform BOD treatment, nitration treatment and denitrification treatment of waste water. CONSTITUTION:An inner cylindrical pipe 22 is arranged to the upper part in a treatment tank 21 and air is blown in said pipe 22 in a bubble from by a blower 24. The upper part in the treatment tank 21 is packed with floatable carriers 25 comprising plastic to fluidize said carriers 25. The lower part in the treatment tank 21 is packed with sedimenting carriers 30 such as sand to fluidize said carriers 30 in the lower part of the tank 21. When raw water is introduced into the treatment tank 21 from the lower part thereof, said raw water passes through the lower anaerobic zone to enter the upper aerobic zone where BOD in waste water is decomposed and removed by BOD oxidizing bacteria in aerobic bacteria adhered to and propagated on the surfaces of the floatable carriers 25. Further, NH4-N in waste water is oxidized to NO3-N by the action of nitriding bacteria in aerobic bacteria.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention forms an aerobic zone and an anaerobic zone in one treatment tank, and performs BOD treatment, nitrification treatment, and denitrification treatment in wastewater in one treatment tank. It relates to a device that allows the work to be carried out within the facility.

[Prior art and its problems]

BACKGROUND ART Conventionally, circulating activated sludge treatment using an activated sludge method has been used to treat BOD, nitrification, and denitrification of nitrogen-containing organic wastewater such as sewage. However, this method has the disadvantage that there is a limit to the amount of microorganisms per unit volume (υ), and that it requires a large area because the processing speed cannot be increased.

Therefore, in recent years, fluidized bed systems, particularly circulating fluidized bed systems, have been proposed and developed, which allow a large amount of microorganisms per unit volume and high-speed processing.

In this method, as shown in FIG. 3, raw water 1 is first introduced into an anaerobic fluidized bed apparatus 3 by a pump 2. In this device, a precipitated carrier 4 having a specific gravity heavier than water is fluidized by a stirrer 5. A part of the treated liquid 6 after the aerobic treatment is returned to this device as a circulation stream 7 by a pump 8, and the No and -N in the circulation stream are transferred to the surface of the settling carrier using the BOD content in the raw water as an organic carbon source. The grown anaerobic bacteria reduce and decompose it into N2 gas, and denitrification is performed. Next, the treatment liquid 9 is introduced into the aerobic fluidized bed apparatus 10. In this device, air is blown into the inner cylindrical pipe 1 through an aeration tube 12 to form a circulation flow, and a sedimentation carrier 13 having a specific gravity heavier than water is caused to flow along with this circulation flow. Aerobic BOD oxidizing bacteria grew on the surface of the sedimentation carrier 13, and the oxidizing bacteria decomposed and removed BOD in the treatment solution, and at the same time, N1 (4-N) in the solution to be treated grew on the surface of the carrier. Due to the action of nitrifying bacteria, which are aerobic bacteria, No.
Oxidized to 3-H. A part of the treated liquid containing No. and -N is returned to the anaerobic fluidized bed apparatus 3 as described above.

However, this method requires two devices, an anaerobic fluidized bed and an aerobic fluidized bed, which makes the process complicated and difficult to maintain, and has the disadvantage that the entire facility becomes large.

[Purpose of the invention]

This invention was made in view of the above circumstances, and its purpose is to form an aerobic zone and an anaerobic zone in one tank, thereby facilitating maintenance and management, and making the device compact. The aim is to obtain a floor-type wastewater treatment device.

[Structure of the invention]

This invention consists of an inner cylinder 6 disposed in the upper part of the processing tank, an aeration pipe that sends bubbly air into the inner cylinder pipe to form a circulating flow inside and outside the inner cylinder pipe, and water flowing along with this circulating flow. A floating carrier having a lighter specific gravity, a raw water introduction pipe and a circulating fluid introducing pipe provided at the bottom of the treatment tank, and a settling carrier having a higher specific gravity than the water that flows with the flow of the circulating fluid introduced into the processing tank. This is a fluidized bed type wastewater treatment equipment that has an aerobic zone in which floating carriers flow in the upper part of the treatment tank and an anaerobic zone in which settled carriers flow in the lower part.

〔Example〕

The present invention will be explained below with reference to the embodiments shown in FIGS. 1 and 2. FIG. 1 shows a continuous fluidized bed wastewater treatment apparatus, in which an inner tube 22 is disposed at the upper part of a treatment tank 21, and an aeration tube 23 is disposed opposite the lower end of the inner tube 22. The air diffuser 23 blows bubble-like air into the inner tube 22 using a blower 24, and its air lift effect produces a circulating flow as shown by the arrow. Also, in the upper part of the treatment tank 21, there is plastic, which has a lighter specific gravity than water.

Floating carriers 25 such as pumice are filled, and flow along with the circulation flow.

On the other hand, a raw water introduction pipe 26 and a circulating water introduction pipe 27 are provided at the bottom of the treatment tank 21, and raw water and circulating water (part of the aerobically treated liquid) are introduced by pumps 28 and 29, respectively. There is.

In the lower part of the treatment tank 21, there is sand that has a higher specific gravity than water.

Sedimentation carriers such as activated carbon, anthracite, plasti, lily etc. 3
0, which flows at the bottom of the tank as the raw water and circulating water rise.

In this way, an aerobic zone in which the floating carriers 25 flow is formed in the upper part of the tank, and an anaerobic zone in which the sedimented carriers 30 flow in the lower part of the tank. In this case, the interface of the anaerobic zone is the diffuser pipe 23
Adjust the specific gravity of the carrier by adjusting the particle size of the carrier, the amount of circulating fluid, etc. so that it is below .

Note that oxygen may be blown into the air diffuser 23 instead of air, or a compressor may be used in place of the blower 24.

Raw water is introduced from the lower part into the treatment tank 21 in which the floating carriers 25 and settling carriers 30 are flowing in this manner. After passing through the anaerobic zone, the raw water enters the aerobic zone, where the BOD in the wastewater is decomposed and removed by BOD oxidizing bacteria, which are aerobic bacteria that adhere to and propagate on the surface of the floating carrier 25. Furthermore, NH4-N in the wastewater is oxidized to No and -N by the action of nitrifying bacteria, which are aerobic bacteria that adhere to and propagate on the surface of the floating carrier 25.

Then, a part of the treated liquid passes through the drain 31,
It is introduced into the anaerobic zone from the bottom of the treatment tank as a circulating fluid.

Here, No and -N in the circulating fluid are reduced and decomposed into N2 gas by the action of denitrifying bacteria, which are anaerobic bacteria, that adhere to and propagate on the surface of the sedimentation carrier 30, using the BOD content in the raw water as an organic carbon source. The treated liquid that has been denitrified in this way passes through the aerobic zone and the drain 31 again, and is discharged from the drainage system 32 to the outside of the system as treated water. If the treated water contains floating surplus sludge (sludge not attached to the carrier) generated inside the treatment tank 21, the treated water is gravity-sedimented outside the system.

It is necessary to perform solid-liquid separation treatments such as coagulation sedimentation and sand filtration.

Figure 2 shows a batch type wastewater treatment device. The difference from the one in Figure 1 is that a water level gauge 41 is provided and the treated water drainage system 42V.
A solenoid valve 43 for extraction is provided which is interlocked with the valve.

In this batch-type device, first, a certain amount of treated water that has undergone BOD, nitrification, and denitrification treatment is drawn out by a solenoid valve 43 that is linked to a water level gauge 41. Next, raw water is introduced into the treatment tank 21. The amount introduced is controlled by a water level meter 4JK. When the inflow of raw water is finished, the blower 24 is operated, and bubble-like air is introduced into the inner cylinder pipe 22 from the aeration pipe 23.

Due to the air lift effect of this air, a circulating flow as shown by the arrow is formed in the upper part of the processing tank 21.

The floating carrier 25 is thus fluidized by air and forms an aerobic zone. BOD in the wastewater is oxidized and decomposed by BOD oxidizing bacteria grown on the surface of the floating carriers 25, and NH4-N in the wastewater is also oxidized and decomposed by aerobic bacteria grown on the surface of the floating carriers 25. It is oxidized to No3-N by nitrifying bacteria. When the BOD and nitrification reactions are completed, the timer stops the operation of the blower 24,
A floating carrier 25 floats above the aerobic zone. Note that the floating carriers 25 are filled in advance so that their lower interface is above the drainage system 42. Next, the circulation pump 29 is operated, and the water to be treated that has undergone aerobic treatment is introduced from the bottom of the treatment tank 2 as a circulating liquid. The sedimentation carrier 30 is fluidized by the water flow of the circulating fluid, and an anaerobic zone is formed.

Note that the upper interface of the anaerobic zone may reach the lower interface of the floating carrier 25. In this anaerobic sea/, No3-N in the circulating fluid is reduced and decomposed into N2 gas by denitrifying bacteria, which are anaerobic bacteria that adhere and propagate on the surface of the sedimentation carrier 30. At this time, as the organic carbon source for denitrification, the BOD content in the raw water that has been retained in the anaerobic zone after the raw water is introduced is used.

Further, while the anaerobic treatment is being performed, the floating carrier 25 blocks the atmosphere and prevents oxygen from entering from the atmosphere.

When the denitrification reaction is completed, the circulation pump 29 is stopped by the timer, and the settling carrier 30 settles to the lower part of the processing tank 21.

Note that the sedimentation carrier 30 is filled in advance so that its upper interface is below the drainage system 42.

Next, the solenoid valve 43 is opened and the treated water is drawn out of the system. The withdrawal of the treated water ends when the electromagnetic valve 43 closes in response to a signal from the water level gauge 41 when the water surface of the treatment tank reaches a set level.

All of the above-mentioned operations are automatically controlled by a water level gauge, timer, etc.

In addition, if surplus sludge (sludge not attached to a carrier) in a suspended state is mixed in the treated water, it is necessary to perform solid-liquid separation treatment such as gravity sedimentation, coagulation sedimentation, sand-filtration, etc. outside the system.

〔Effect of the invention〕

According to this invention, BOD of wastewater can be achieved with one device.

Since nitrification and denitrification are performed, maintenance is easy and the equipment can be made more compact. Furthermore, both continuous and batch processing methods can be employed.

Furthermore, since the floating carriers are made to flow throughout the entire aerobic zone due to the air lift effect, even if the specific gravity of the floating carriers is relatively light, the fluidity is good (improving the reaction efficiency regarding BOD removal and nitrification).

[Brief explanation of drawings]

FIGS. 1 and 2 are schematic illustrations of a fluidized bed wastewater treatment apparatus showing an embodiment of the present invention, and FIG. 3 is a schematic illustration of a conventional fluidized bed wastewater treatment apparatus.21. - Processing tank, 22... Inner cylinder pipe, 23... Diffusion pipe, 24... Blower, 25... Floating carrier, 26...
・Raw water introduction pipe, 27... Circulating water introduction pipe, 28.29.
... Pump, 30... Sedimentation carrier, 31... Mogushizeki, 32... Drainage system, 4)... Water level gauge, 42...
Drainage system, 43...Solenoid valve.

Claims (1)

[Claims] An inner cylindrical pipe disposed at the upper part of the processing tank, an aeration pipe that sends bubble-like air into the inner cylindrical pipe to form a circulation flow inside and outside the inner cylindrical pipe,
Floating carriers having a specific gravity lighter than water flowing with this circulation flow, a raw water introduction pipe and a circulating fluid introduction pipe provided at the bottom of the treatment tank, and at least a floating carrier having a specific gravity lighter than water flowing with the flow of the circulating fluid introduced into the treatment tank. A fluidized bed wastewater treatment device comprising a settling carrier having a specific gravity heavier than flowing water, and forming an aerobic zone in the upper part of the treatment tank in which the floating carrier flows and an anaerobic zone in the lower part in which the settling carrier flows.