JPS6229118B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for biologically treating organic wastewater such as sewage by passing the water through a fixed bed catalytic oxidation tower configured in a serpentine tube shape and having a filler on which aerobic microorganisms are attached. It is something.

In recent years, in the treatment of organic wastewater, catalytic oxidation towers, which are relatively easy to operate and manage, have come to be used instead of activated sludge equipment.

There is a fixed-bed catalytic oxidation tower in which biological treatment is performed by flowing upward flow of water and air into the catalytic oxidation tower from the bottom of a layer of packing material on which aerobic microorganisms have grown. Such fixed-bed catalytic oxidation towers are usually open to the atmosphere, but in order to increase the BOD volumetric load, there is a method of using a closed fixed-bed catalytic oxidation tower and performing biological treatment under pressure higher than atmospheric pressure. .
But high BOD volumetric loads can be obtained,
Even in such a pressurized catalytic oxidation tower, the bed height of the packing material on which aerobic microorganisms are attached is at least 2
~4m is required, and if this is done with one tower, the tower will be high-rise and the installation location will be limited.

The present invention solves the drawbacks of the conventional biological treatment method using a pressurized catalytic oxidation tower, and is a fixed bed catalytic oxidation method in which a plurality of pipes are connected with a U-shaped tube to form a serpentine tube. The purpose is to perform biological treatment efficiently using a simple tower by performing biological treatment under pressure using a tower. That is, in biologically treating organic wastewater, the present invention converts the water to be treated in which air is dissolved under high atmospheric pressure into a U-shaped pipe having a layer of filler on which aerobic microorganisms are attached. The feature is that the water is passed through a fixed bed catalytic oxidation tower connected in a meandering tube shape.

Embodiments of the present invention will be described below with reference to the drawings. The figure is an explanatory diagram of a flow showing an example of the biological treatment method of organic wastewater of the present invention, and the fixed bed catalytic oxidation tower 3 is configured, for example, in a spiral tube shape by connecting four pipes 5 with a U-shaped pipe 4. , Seal completely airtight. In addition, the lower part of both ends of the oxidation tower 3,
A reverse inlet pipe 15 is communicated with the U-shaped pipe 4 that connects the lower end of the pipe 5, and a backwash outlet pipe 16 is communicated with the U-shaped pipe 4 that connects the upper end of the pipe 5. Further, each pipe 5 is filled with granular materials such as gravel or crushed stone, or a filler material 6 such as a Raschig ring, a mesh body, or a honeycomb tube.

A pressurized tank 2 that dissolves air 12 in the water to be treated 11 under pressure is connected to the inlet side of the fixed bed catalytic oxidation tower 3, and a flotation separation device is connected to the outlet side of the oxidation tower 3 via a pressure control valve 10. Connect 9. The pressurized tank 2 is equipped with a pressure gauge 18, a safety valve 19, and a gas blowing device 20, and the pressure inside the pressurized tank 2 and the oxidation tower 3 is lowered from atmospheric pressure by the pressure regulating valve 10, the safety valve 19, and the gas blowing device 20. Maintain high pressure. 1 is a storage tank for the water to be treated 11; 7 is a compressor; 8 is an ejector; 17 is a pump; 21 is a support screen for the filler 6, which allows water and air to pass through; is of a structure that does not allow it to pass through.

Next, the operation of the present invention will be explained. First, pump 17
is driven to cause the water 11 to be treated in the storage tank 1 to flow into the pressurized tank 2 via the ejector 8. At this time, the air 12 compressed by the compressor 7 is mixed with the water 11 to be treated in the ejector 8. Note that since the pressure inside the pressurized tank 2 is adjusted to be higher than atmospheric pressure, a larger amount of air 12 mixed with the water to be treated 11 is dissolved in the pressurized tank 2 than under atmospheric pressure. Next, the water to be treated 11 in the pressurized tank 2 in which a large amount of air 12 has been dissolved is transferred to the fixed bed catalytic oxidation tower 3.
It flows from the lower end and passes through the layer of packing material 6 of each pipe 5 of the oxidation tower 3 configured in a serpentine tube shape while alternating upward and downward flows. Since the fixed bed catalytic oxidation tower 3 is pressurized by the pressure control valve 10, the air 12 dissolved in the water to be treated 11 is not released as bubbles. Therefore, the layer of the filler 6 is not disturbed by the bubbles of the air 12, and the efficiency is improved by bringing the water 11 to be treated containing a large amount of dissolved air into contact with the aerobic microorganisms that have grown on the filler 6. Can be easily treated biologically. Furthermore, by changing the pressure inside the pressurized tank 2 and the fixed bed catalytic oxidation tower 3, the amount of air 12 dissolved in the water to be treated 11 can be changed, so that the organic components of the water to be treated 11 can be reduced. The amount of air 12 can be freely controlled depending on the degree of contamination, so that catalytic oxidation can always be carried out under ideal conditions. Note that the amount of air 12 dissolved in the water to be treated 11 is proportional to the pressure of the system, but the higher the pressure in the pressurized tank 2 and the fixed bed catalytic oxidation tower 3, the faster the pump 17 that supplies the water to be treated 11 will be. Since the discharge pressure of the compressor 7 of the air 12 becomes large and the power cost increases, the pressure in the pressurized tank 2 and the fixed bed catalytic oxidation tower 3 is approximately 1.5~
It is good to adjust to 5Kg/cm ² , preferably 2 to 3Kg/cm ² .

Further, the residence time of the water to be treated 11 in the pressurized tank 2 is 1 to 10 minutes, usually 2 to 3 minutes.

For example, when using granular materials as the filler 6, the smaller the diameter, the larger the surface area, and the larger the amount of aerobic microorganisms that can attach to it. If the diameter is large, the surface area will be small and the purification efficiency will be reduced, so the diameter is preferably 1 to 50 m/m, preferably 6 to 50 m/m.

Next, the outlet water 13 of the fixed bed catalytic oxidation tower 3 is made to flow into the flotation separator 9 through the pressure regulating valve 10 and released to atmospheric pressure. When released to the atmosphere in the flotation separator 9, the air 12 dissolved under pressure in the outlet water 13 becomes fine bubbles, and suspended substances contained in the outlet water 13 adhere to these minute bubbles. It floats on the water surface of the flotation separation device 9. Therefore, by removing these floating substances, clear treated water 14 can be obtained.
can be obtained.

If the packing material 6 of the fixed bed catalytic oxidation tower 3 becomes clogged, the flow of the water to be treated 11 is interrupted, the catalytic oxidation tower 3 is opened to atmospheric pressure, and the backwash inlet pipe 15 is opened.
Water or water and air is passed through each pipe 5 in an upward flow to backwash the filling material 6, and backwash wastewater is discharged from a backwash outlet pipe 16.

Since the fixed bed catalytic oxidation tower 3 of the present invention forms a layer of filler 6 in each of the plurality of pipes 5,
The bed height of the filler material 6 per one pipe 5 can be lowered, and therefore it can be installed in places where the conventional one-column type cannot be installed because the device is too high-rise, such as inside an existing building. Furthermore, since commercially available pipes 5 and U-shaped tubes 4 can be used, the device can be manufactured compactly and at low cost.

As shown in the figure showing an example of the embodiment, the fixed bed catalytic oxidation tower 3 is constructed by vertically erecting pipes 5 and connecting them with a U-shaped pipe 4, or by arranging the pipes 5 horizontally and connecting them with a U-shaped pipe 4. They may be configured by being connected by a pipe 4, and the method of connecting the pipe 5 and the U-tube 4 can be selected depending on the installation location.

Furthermore, since the fixed bed catalytic oxidation tower 3 has a meandering pipe structure, each pipe 5 can be backwashed individually, which is more effective than when backwashing is performed from the bottom of a high packing layer as in a single tower type. Backwashing can be done reliably in a short time without causing insufficient washing. Further, it has various advantages over the conventional method in that only one pipe 5 can be selectively backwashed.

Examples of the present invention will be described below.

Example A closed fixed-bed catalytic oxidation tower was used, in which four commercially available pipes with a diameter of 1 m and a length of 1.5 m were erected vertically and connected with a commercially available U-shaped pipe to form a serpentine tube. A steel pressurized tank for dissolving air in the water to be treated and a flotation separation device in the latter stage were arranged as shown in the diagram showing an example of an embodiment of the present invention. Each pipe was filled with 20 to 30 mm C/gravel as a filler to a layer height of 1 m. General building wastewater with a BOD value of 200mg/cm2 is used as the water to be treated, and air compressed to 5Kg/ ^cm2 by a compressor is mixed with the water by an ejector, and the mixture flows into a pressurized tank with a residence time of 2 to 3 minutes. The inside of the pressurized tank was 3 to 5 kg/
Pressurize to cm ² to completely dissolve air in the water to be treated.
Oxygen in the water to be treated was approximately 30 to 50 ppm. The water to be treated that flowed out of the pressurized tank was flowed into a fixed bed catalytic oxidation tower at a flow rate of about 16 m ³ /h, and brought into contact with the gravel on which aerobic microorganisms had grown to perform biological treatment. The pressure inside the fixed bed catalytic oxidation tower was set to 3 at the outlet side of the oxidation tower.
Kg/ ^cm2 was maintained. Fixed bed catalytic oxidation tower outlet water
The BOD value was 40 mg/, and the BOD value of the treated water that passed through the flotation separator was 20 mg/, indicating that it was clear. A high BOD volumetric load of 5 kg/BODm ³ /day was achieved in the fixed bed catalytic oxidation tower.

[Brief explanation of the drawing]

The figure is an explanatory diagram showing a flow of an example of an embodiment of the present invention. 1... Storage tank, 2... Pressurized tank, 3... Fixed bed catalytic oxidation tower, 4... U-shaped pipe, 5... Pipe, 6
...Filling material, 9...Flotation separation device, 10...Pressure control valve, 11...Water to be treated, 12...Air, 15
...Backwash inlet pipe, 16...Backwash outlet pipe.

Claims (1)

[Claims] 1. When biologically treating organic wastewater, the water to be treated with dissolved air under pressure greater than atmospheric pressure is
A living body of organic wastewater, characterized in that water is passed through a fixed bed catalytic oxidation tower configured in a serpentine tube shape by connecting a plurality of pipes with a layer of filler on which aerobic microorganisms are attached by a U-shaped tube. Processing method.