JPH0681699U - Oxygen supply device for deep aeration tank - Google Patents

Abstract

(57) [Summary] [Purpose] Both oxygen supply capacity and stirring capacity are sufficient,
An oxygen supply device for a deep depth aeration tank having high power efficiency is provided. [Structure] Introducing pipe 5 vertically provided in aeration tank 1
And a mechanical air diffuser 7 located in the upper part of the intake pipe 5 for dispersing the oxygen-containing gas in the water to be treated, and a lower part in the intake pipe 5 for introducing the water to be treated into the intake pipe 5. An oxygen supply device is configured with the circulation pump 8 that causes downward flow. [Effect] Since the amount of the oxygen-containing gas dispersed in the upper part of the intake pipe dissolved in the water to be treated increases as the water depth increases, a sufficient amount of oxygen is supplied to the water to be treated.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an oxygen supply device for a deep depth aeration tank used for treating wastewater such as sewage.

[0002]

[Prior art]

2. Description of the Related Art Conventionally, various biological treatment methods have been carried out in wastewater treatment plants such as sewage. For example, in the floating type treatment such as the activated sludge method, the water to be treated flows in the biological reaction tank by supplying the water to be treated to the biological reaction tank, causing the water to flow in the reaction tank and performing aeration. In the meantime, the nitrogen content in the water to be treated is removed by the action of microorganisms. The reaction tank for that purpose is usually designed and operated at a water depth of about 10 m at the maximum, and aeration devices such as a diffuser plate, a diffuser pipe, and a mechanical aerator for supplying oxygen to such a reaction tank have a depth of water. It is installed around 4m. The discharge pressure of the blower at this time is about 5000 mmAq, and the maximum aeration capacity of one aeration device is about 1000 m ³ .

[0003]

[Problems to be solved by the device]

However, in a large city where the land for the treatment plant cannot be secured sufficiently, if the aeration tank capacity needs to be increased, the reaction tank must be deepened to a depth of about 20 to 30 m. The maximum capacity is 3000 m ³ and the conventional aerator does not have sufficient oxygen supply capacity and stirring capacity. Moreover, the discharge pressure of the blower becomes very high, and as a result, the power efficiency (kWh / kg -O ₂ ) of the aeration device becomes low.

The present invention solves the above problems, and an object of the present invention is to provide an aerator having sufficient oxygen supply ability and stirring ability and high power efficiency.

[0005]

[Means for Solving the Problems]

 The oxygen supply device for a deep depth aeration tank of the present invention is an oxygen supply device that is installed by immersing it in the water to be treated in the aeration tank. An inlet pipe that is open and has a lower end that opens at the bottom of the tank, and a mechanical diffuser that is located above the inlet pipe and that disperses the oxygen-containing gas supplied from the air supply means outside the tank into the water to be treated. An apparatus and a circulation pump, which is located in the lower part of the intake pipe, allows the water to be treated in which the oxygen-containing gas is dispersed by the mechanical diffuser to flow downward in the intake pipe.

[0006]

[Action]

 With the above configuration, the water to be treated has the oxygen-containing gas dispersed by the mechanical air diffuser in the upper part of the intake pipe, and is drawn downward in the intake pipe by the circulation pump provided in the lower part of the intake pipe and the guide function of the intake pipe. Allow to flow to the bottom of the tube. At this time, the oxygen-containing gas is supplied as fine bubbles by the air diffuser, and the amount of the oxygen-containing gas dissolved in the water to be treated increases as the water depth increases. The amount of oxygen dissolved in the water increases. Further, the water to be treated flowing out from the lower end of the intake pipe rises on the outer peripheral side of the intake pipe, so that a circulating flow is generated in the tank. As a result, the water to be treated in the tank is agitated and mixed with the activated sludge in a state where oxygen is sufficiently supplied, so that the water to be treated can be treated even by using a deep aeration tank.

[0007]

【Example】

 An oxygen supply device for a deep aeration tank according to an embodiment of the present invention will be described below with reference to FIG. Reference numeral 1 denotes an aeration tank, and the tank 1 is configured to be able to store the water to be treated having a water depth of 20 to 30 m, and the water to be treated in the tank 1 is mixed with activated sludge. Above the aeration tank 1, there are opened a raw water supply pipe 2 for supplying raw water and a sludge return pipe 3 for returning the activated sludge collected in a sedimentation pond at a later stage (not shown) to the aeration tank 1, An outflow pipe 4 for outflowing a part of the water to be treated in the tank 1 is provided above the tank 1. Inside the tank 1, a lead-in pipe 5 having a length of 14 to 24 m is installed in a substantially central position in the horizontal direction of the tank 1 so as to extend upward and downward, and the upper end of the lead-in pipe 5 is a tank. It opens below the water surface in the upper part of 1 and the lower end opens about 2 m from the bottom of tank 1. A mechanical air diffuser 7 is provided in the upper part of the intake pipe 5 and at a position 2 to 4 m below the water surface, connected to an air supply means such as a blower 6 outside the tank 1, and the mechanical air diffuser 7 is provided. The vaporizer 7 is adapted to disperse the oxygen-containing gas supplied from the blower 6 in the water to be treated at the upper part of the intake pipe 5. Further, a circulation pump 8 is provided at a lower portion of the intake pipe 5 and at a water depth of 10 to 20 m, and the treated water in the intake pipe 5 is 1.5 m / sec by the circulation pump 8. It is configured to flow downward at the above flow rate and to flow out from the lower end of the intake pipe 5. At this time, the water to be treated flowing out from the lower end of the intake pipe 5 rises on the outer peripheral side of the intake pipe 5, so that an in-tank circulation flow is generated in the aeration tank 1.

The operation of the above configuration will be described below. In the tank 1, raw water is supplied from the raw water supply pipe 2 and sludge is returned from the sludge return pipe 3, the treated water in the tank 1 is biologically treated, and the treated water in the tank 1 is treated. Part of the water flows out from the outflow pipe 4. The water to be treated in the tank 1 flows into the intake pipe 5 from the upper end of the intake pipe 5, and is mixed with the oxygen-containing gas supplied from the blower 6 through the mechanical diffuser 7 in the upper part of the pipe 5. Then, the water to be treated flows downward in the intake pipe 5 by the action of the circulation pump 8, flows out from the lower end thereof, and rises outside the intake pipe 5. At this time, the oxygen-containing gas is dispersed as fine bubbles by the mechanical air diffusing device 7, and is dispersed into the water to be treated flowing downward at a flow velocity faster than the ascending velocity of the bubbles, thereby forming fine bubbles. To be done. Since the fine bubbles dissolve in the water to be treated with high efficiency due to the increase in solubility according to the water depth, a sufficient amount of oxygen is supplied to the water to be treated. As a result, the water to be treated is sufficiently and surely supplied with oxygen in the intake pipe 5, and is well agitated and mixed with the activated sludge inside and outside the intake pipe 5, so that the aeration tank 1 with a deep water depth is provided. Even in Japan, the activated sludge method can be sufficiently performed.

In the above, since the bubbles of the oxygen-containing gas use the water depth twice from the upper part to the lower part of the tank 1 and from the lower part to the upper part, the oxygen dissolution efficiency is increased from the conventional maximum of 20% to 50%. and it increases the power efficiency increases to conventional maximum 2.0kwh / kg -O ₂ Hekara 3.5kwh / kg -O _2.

[0010]

[Effect of device]

 As described above, according to the present invention, oxygen as fine bubbles is supplied to the water to be treated at the upper part of the intake pipe by the mechanical air diffuser, and the water to be treated is lowered in the intake pipe by the circulation pump. With the configuration in which the amount of oxygen dissolved in the water to be treated is increased, sufficient oxygen can be supplied to the water to be treated in the tank. Further, a downward flow in the intake pipe causes a circulating flow in the tank, and the water to be treated and the activated sludge are well mixed with stirring. As a result, in an aeration tank with a large depth, activated sludge treatment can be performed in a state where oxygen is sufficiently and reliably supplied to the treated water and the treated water and the activated sludge are well stirred and mixed. At this time, power efficiency is also high.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an oxygen supply device for a deep depth aeration tank according to an embodiment of the present invention.

[Explanation of symbols]

 1 Aeration tank 5 Intake pipe 6 Blower (air supply means) 7 Mechanical air diffuser 8 Circulation pump

Claims (1)

[Scope of utility model registration request] 1. An oxygen supply device provided by being immersed in water to be treated in an aeration tank, the oxygen supply device being provided in the aeration tank in a vertical direction, with an upper end opening at an upper part of the tank and a lower end being a bottom part of the tank. An opening intake pipe, a mechanical air diffuser located in the upper part of this intake pipe to disperse the oxygen-containing gas supplied from the air supply means outside the tank into the water to be treated, and a lower part inside the intake pipe An oxygen supply apparatus for a deep depth aeration tank, comprising: a circulation pump that causes the water to be treated in which the oxygen-containing gas is dispersed by the mechanical air diffuser to flow downward in the intake pipe.