JPH11253982A - Method and apparatus for treating waste water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waste water treatment apparatus capable of preventing the sedimentation of a carrier the lower part of the air diffusion device arranged in a reaction tank or to the lower part of the air diffusion device of an aeration tank and an apparatus therefor. SOLUTION: Air diffusing devices 3 are arranged to an aeration tank 1 receiving a carrier 2 growing bacteria to biologically treat waste water or to aeration sub-units connected by partition walls containing screens capable of separating the carrier 2, and an underwater stirrer 5 generating water streams in the parts under the air diffusion devices 3 is arranged and the carrier 2 under the air diffusion devices 3 is fluidized by the water streams from the underwater stirrer 5 to be prevented from sedimentation under the air diffusion devices 3. In the waste treatment apparatus thus constituted, the sedimentation of the carrier 2 under the air diffusion devices 3 is eliminated and the treatment efficiency as the aeration tank is kept and the treatment capacity corresponding to a plan value can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for treating wastewater, and more particularly to biologically purifying organic and inorganic substances in wastewater. The present invention relates to a wastewater treatment method and a device using a microorganism-immobilized carrier immobilized, attached, or bonded and immobilized on a particulate carrier mainly composed of an inorganic substance.

[0002]

2. Description of the Related Art As is well known, a wastewater treatment apparatus includes a reaction tank in a standard activated sludge method and a reaction tank charged with a microorganism-immobilized carrier. In a reaction tank containing a microorganism-immobilized carrier, it is possible to maintain a high concentration of microorganisms compared to a reaction tank in the standard activated sludge method, and to increase the treatment efficiency of decomposing organic and inorganic substances in wastewater. It has the advantage that it can be. A device provided with a diffuser for supplying oxygen for promoting decomposition by microorganisms in a reaction tank is called an aeration tank.

FIG. 4 is a schematic view of a wastewater treatment apparatus using a microorganism-immobilized carrier. FIG. 4A is a plan view of the apparatus, and FIG. 4B is a sectional view taken along the line XY. FIG.
The wastewater treatment apparatus shown in FIG. 1 includes an aeration tank 1 having a depth of about 5 m into which a microorganism-immobilized carrier 2 is charged, and a diffuser 3 connected to a diffuser pipe 3a for diffusing air from the bottom of the tank. It is formed with a pneumatic aeration tank. Normally, the diffuser 3 of the full-surface diffusion method is 200 mm to 600 mm from the bottom of the tank.
It is installed above. In addition, the air diffuser 3 has a low stirring effect due to the blowing of air from the bottom of the tank, so that the water flow rate required for the flow of the carrier 2 cannot be sufficiently obtained.
Tend to deposit as deposits 6 on the bottom of the tank.

[0004] Such deposition of the carrier 2 in the lower portion of the aeration device 3 of the aeration tank 1 results in the generation of dead space in the aeration tank 1 and a decrease in the amount of the carrier contributing to the treatment. This will reduce the processing capacity of the processing equipment. Conventionally, in order to prevent such carrier deposition in the lower part of the air diffuser 3, a method of filling the space below the air diffuser 3 with urethane resin or the like is performed, or a carrier having an amount corresponding to the amount of the carrier to be deposited is used. In order to prevent a decrease in processing capacity.

[0005]

In the conventional aeration tank, as a method for preventing the deposition of the carrier on the lower portion of the air diffuser, a method of filling the space below the air diffuser with urethane resin or the like has been used. There is a problem that a material cost and a labor cost for performing the filling work of the resin or the like are required. In addition, since the lower region of the air diffuser filled with urethane resin or the like becomes a dead space, a large reaction tank is constructed in advance in consideration of the dead space to secure a necessary volume as a reaction tank. And the construction cost increases.

Further, in the conventional aeration tank, the amount of the carrier deposited in the lower part of the aeration device is replenished to prevent a reduction in the processing capacity. In such a method, the amount of the carrier is increased as the required amount of the carrier increases. There is a problem that the cost becomes large. In addition, the volume occupied by the carrier deposited in the lower part of the aeration device becomes a dead space, and the actual volume of the reaction tank is reduced, resulting in deterioration of the treatment water quality. There is a problem that sludge accumulates and decomposes in the space to be treated, resulting in deterioration of treated water quality.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and prevents deposition of a microorganism-immobilized carrier on the lower part of an aeration device installed in a reaction tank or an aeration tank. The present invention provides a wastewater treatment method and a device therefor.

[0008]

Means for Solving the Problems The present invention has been made in view of the above problems, and the invention of claim 1 is directed to an aeration tank or a tank for biologically treating wastewater by adding a carrier for growing microorganisms. An aeration device for supplying oxygen is disposed in an aeration tank subunit connected by a partition wall including a separable screen of the carrier, and a water flow is generated by an underwater agitator disposed below the aeration device. The wastewater treatment method is characterized in that the carrier is caused to flow to prevent the carrier from depositing in the lower part of the air diffuser. According to this configuration, the carrier at the lower part of the diffuser is caused to flow by the water flow of the underwater stirrer, and the deposition of the carrier in the underwater stirrer at the lower part of the diffuser is eliminated, and the processing efficiency as a reaction tank is maintained. , And a processing capacity as designed.

[0009] The invention of claim 2 provides an aeration tank for introducing a carrier for growing microorganisms and biologically treating wastewater or an aeration tank subunit connected by a partition wall including a separable screen for the carrier. A wastewater treatment apparatus, comprising: an aeration device for supplying oxygen arranged in the aeration tank and the aeration subunit; and a submersible agitator arranged below the aeration device. According to this configuration, the carrier in the lower part of the air diffuser is caused to flow by the water flow by the underwater agitator, and the deposition on the carrier in the underwater agitator below the air diffuser is eliminated, and the processing efficiency as a reaction tank is maintained. ,
In addition, it is an apparatus capable of obtaining a processing capacity as designed without generating dead space.

The invention according to claim 3 is the wastewater treatment apparatus according to claim 2, wherein the underwater stirrer is installed at an interval of 2 m to 20 m at the bottom of the tank. According to this configuration, since a water flow can be generated over the entire lower surface of the air diffuser, the carrier can be floated without waste and dispersed throughout the tank. Has the ability to maintain the ability.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a wastewater treatment method and apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing an embodiment of the wastewater treatment device of the present invention. FIG. 1A is a plan view thereof, and FIG. 1B is a cross-sectional view thereof along the line XY. In FIG. 1, a wastewater treatment apparatus includes an aeration tank 1 into which a microorganism-immobilized carrier 2 is charged, an oxygen supply air diffusion apparatus 3 connected by an air diffusion pipe 3a through which air is supplied to the entire bottom of the aeration tank 1, A lower part of the air diffuser 3 and an underwater stirrer 5 installed substantially at the center of the bottom of the aeration tank 1. The microorganism-immobilized carrier 2 is a particulate substance mainly composed of an organic polymer substance or an inorganic substance, and is used for immobilizing or binding and immobilizing microorganisms.

FIG. 2 is a schematic diagram showing another embodiment of the wastewater treatment apparatus of the present invention. FIG. 1A is a plan view thereof, and FIG. 1B is a cross-sectional view thereof along the line XY.
In the wastewater treatment apparatus shown in the figure, the aeration tank 1 has a subunit 1a,
1b. A partition wall 4 including a carrier separation screen is installed at the outflow portion of the aeration tank at the boundary between the subunits 1a and 1b to separate the carrier 2 and the water to be treated.
Subunit 1a is an aeration tank subunit. The air diffuser 3 and the underwater stirrer 5 are arranged under the same conditions as in FIG.

The wastewater treatment apparatus according to these embodiments includes an aeration tank 1 or a partition wall 4 including a separable screen of a carrier.
This is an aeration tank of the whole-surface aeration method in which the aeration device 3 is installed on the entire bottom surface of the aeration tank subunit 1a connected by the air. The air is sent from the aeration device 3 to the treated water in the tank. The environment suitable for growing microorganisms is maintained on the carrier 2 which is suspended and dispersed. The underwater stirrer 5 has a function of preventing the carrier 2 from being deposited on the bottom by the water flow. The underwater stirrer 5 is installed in a space having a depth of about 200 mm to 600 mm extending from the bottom of the tank below the air diffuser 3 to the lower part of the air diffuser 3. A sufficient water flow rate for the flow of the carrier 2 is generated to prevent deposition of the carrier 2 at the lower portion of the air diffuser 3.

The underwater stirrer 5 needs to have a water flow rate such that the carrier 2 flows sufficiently at the bottom of the diffuser 3. , And blow up to stir. Conversely, the water to be treated above the underwater stirrer 5 is blown downward to give a sufficient water flow to the bottom of the diffuser 3 to obtain the dispersion effect of the carrier 2.

The length and width of the aeration tank 1 into which the carrier 2 is charged or the length and width of the aeration tank subunit 1a connected by a partition wall 4 including a separable screen of the carrier 2 are set to 2.
If it is within 20m from m, as shown in FIGS. 1 and 2,
The underwater stirrer 5 can generate a sufficient water flow by being arranged at substantially the center of the tank bottom.

Further, the length and width of the aeration tank are from 2 m to 2 m.
In the case of having a relatively large volume of 0 m or more, as shown in FIG.
Is 2 m to 20 m, preferably 5 m to
The interval is 10 m. By arranging at such intervals, it becomes possible to obtain a water flow rate necessary for flowing the carrier 2 under the air diffuser on the entire bottom of the tank.
A predetermined number may be arranged according to the area of the bottom surface of the aeration tank. One underwater stirrer 5 may be arranged per predetermined area, for example, one underwater stirrer 5 may be arranged at a rate of 5 m ² .

[0017]

Next, an embodiment of the present invention will be compared with a conventional example to explain its effectiveness. This embodiment is an aeration tank of the wastewater treatment apparatus of FIG. 2 using a full-surface aeration method, and an underwater stirrer 5 is disposed at the center of the bottom of the tank. The submerged stirrer 5 was used to generate a water flow velocity over almost the entire bottom of the tank, thereby preventing the deposition of the carrier 2. The effectiveness of the present embodiment will be described by a comparative experiment between the present embodiment and a conventional example of the aeration apparatus without the underwater stirrer 5 shown in FIG. Both wastewater treatment devices have the same shape, and each aeration device has the same shape and a water area load of 10%.
A sedimentation basin satisfying m / day or less was connected and water was taken. Table 1 shows the water quality of the sewage supplied from the sedimentation basin to the water treatment apparatus. Table 2 shows the processing results of the present embodiment and the conventional example, and shows the average values of the water velocities in the x, y, and z-axis three directions of the water to be treated in the lower part of the air diffuser.

[0018]

[Table 1]

[0019]

[Table 2]

The effectiveness is clear from Table 2. In this example, it was proved that a good treatment result of the wastewater can be obtained by installing the underwater stirrer below the air diffuser. When the bubble generator as a comparative example was not installed, the mixture of the carrier and the sludge was deposited on the entire lower surface of the diffuser at the bottom of the tank as a result of observation from the side of the aeration tank made of transparent vinyl chloride. In the present example, it was found that the average water flow velocity in the lower part of the air diffuser in Table 2 was increased, and the carrier was able to flow sufficiently.

[0021]

As described above, according to the present invention,
In treating wastewater in the aeration tank charged with the microorganism-immobilized carrier, the submerged stirrer is installed below the oxygen supply diffuser for the aeration tank or the aeration tank subunit in which the carrier is charged. A water flow can be generated in the lower part, and since such a simple and easy method and apparatus can prevent the deposition of the carrier in the lower part of the diffuser, the construction cost of the wastewater treatment apparatus can be reduced. There is an advantage that an existing aeration tank or reaction tank can be easily improved.

Further, according to the present invention, since the carrier can be sufficiently dispersed in the aeration tank, there is an advantage that the volume of the aeration tank and the whole of the loaded carrier can be effectively used. It is possible to obtain the treatment capacity as designed, and to sufficiently disperse and disperse the loaded carrier, and to stably treat the wastewater by the microorganisms that parasitize the organic polymer substances and the like in the wastewater on the carrier. There is an advantage of having an effect.

[Brief description of the drawings]

FIG. 1A is a plan view showing an embodiment of an aeration tank as a wastewater treatment apparatus according to the present invention, and FIG. 1B is a cross-sectional view taken along the line XY.

FIG. 2A is a plan view showing an embodiment of an aeration tank subunit which is a wastewater treatment apparatus according to the present invention, and FIG. 2B is a cross-sectional view taken along line XY.

FIG. 3 is a sectional view showing another embodiment of the wastewater treatment apparatus according to the present invention.

FIG. 4A is a plan view showing an example of an aeration tank as a conventional wastewater treatment apparatus, and FIG. 4B is a cross-sectional view taken along the line XY.

[Explanation of symbols]

 Reference Signs List 1 aeration tank 2 carrier for immobilizing microorganisms 3 diffuser 4 partition wall 5 underwater stirrer

Continued on the front page (72) Inventor Shinichi Endo 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Yukihiko Okamoto 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Stock In company

Claims (3)

[Claims] Aeration for supplying oxygen to an aeration tank for introducing a carrier for growing microorganisms and biologically treating wastewater or an aeration tank subunit connected by a partition wall including a separable screen for the carrier. Wastewater characterized in that a device is arranged, a carrier is caused to flow by generating a water flow by an underwater stirrer arranged below the aeration device, and the carrier is prevented from being deposited at a lower portion of the aeration device. Processing method. 2. An aeration tank for introducing a carrier for growing microorganisms and biologically treating wastewater, or an aeration tank subunit connected by a partition wall including a separable screen for the carrier, and the aeration tank and aeration. A wastewater treatment apparatus comprising: an oxygen supply air diffuser arranged in a subunit; and a submersible agitator arranged below the air diffuser. 3. The underwater stirrer is provided at the bottom of the tank from 2 m to 2 m.
The wastewater treatment device according to claim 2, wherein the wastewater treatment device is installed at an interval of 0 m.