JPH1128490A - Fluidized bed type sewage treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily execute the sepn. of microorganism adhesion carriers and to facilitate maintenance and control by providing the device with a means for withdrawing the microorganism adhesion carriers in the treated water gathered in the bottom of a carrier sepn. tank and returning the carriers to an aeration tank by the vortex generated by a means of admitting the treated water to the carrier sepn. tank and forming the vortex. SOLUTION: The sewage introduced into the aeration tank 1 is decomposed by microorganisms and purified within the tank where the microorganism adhesion carriers flow by blowing air therein from an air diffuser 2. The treated water flows together with the microorganism adhesion carriers and the suspended sewage through an inflow channel 11 into the carrier sepn. tank 10. At this time, the inflow rate and flow velocity of the treated water are adequately set by the control of a valve 12 and the vortex is formed in the carrier sepn. tank 10 by this inflow, by which the microorganism adhesion carriers are gathered to the center of the vortex and are stagnated at the bottom. The floating up microorganism adhesion carriers are gathered together with the floating materials by a trap and are dropped downward of a water collecting tray 14 where the carriers settle and accumulate at the bottom. The accumulated microorganism adhesion carriers 40 and solid contents are withdrawn and are returned from a carrier return pipe 19 to the upstream side of the aeration tank 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluidized bed type sewage treatment apparatus for aerobically treating sewage while fluidizing particles (hereinafter referred to as microorganism-adhered carriers) having microorganisms attached thereto in a tank.

[0002]

2. Description of the Related Art A fluidized bed for biologically decomposing organic substances in sewage by bringing microbial-adhered carriers into a tank, blowing air into the tank, and bringing the microorganism-adhered carriers into contact with sewage while flowing. The sewage treatment system has a very large surface area of the carrier particles to which the microorganisms are attached, and therefore can hold a large amount of microorganisms in the tank. Therefore, the device is compact and capable of high-load operation. It is a device that has many advantages such as, for example, attention.

FIG. 5 is a sectional view showing an example of a conventional fluidized bed type sewage treatment apparatus. In this device, an air diffuser 2 is provided at the bottom of an aeration tank 1 so that air is blown into sewage in the tank. Reference numeral 40 denotes a microorganism-adhering carrier flowing in sewage. At the outlet of the treated water, a screen 30 for preventing the microorganism-adhering carrier 40 from flowing out is provided.

[0004] In a fluidized bed type sewage treatment apparatus,
In order to save energy for flowing the microorganism-adhering carrier, the material of the particles to which the microorganisms are attached is selected from substances having a specific gravity as small as possible.For example, in plastics or activated carbon, the specific gravity is slightly larger than the specific gravity of water. Things are used. The particles have a size of about several mm.

When sewage is treated by the above-described apparatus, sewage is introduced into the aeration tank 1, and air is blown from the aerator 2 to purify the sewage while flowing the microorganism-attached carrier 40. The purified treated water is discharged together with the suspended sludge through the screen 30 and sent to a sedimentation basin for separating and removing the sludge. The microorganism-adhering carrier 40 is prevented from flowing out, remains in the tank, and circulates in the tank while flowing again to purify sewage.

[0006]

As described above, the microorganism-attached carriers are small particles, and therefore, the screen width for separating the microorganism-attached carriers is very narrow.
Sewage contains various solids. For this reason, in the above-mentioned conventional apparatus, there is a problem that the screen is clogged and the operation is hindered.

[0007] When the solids start to clog the screen, a microbial membrane is formed on the clogged solids, and other solids tend to adhere thereon. Then, the degree of clogging becomes increasingly severe. When the screen is clogged, the water passing area decreases, the water level in the aeration tank rises, and it becomes impossible to maintain a predetermined processing capacity. Therefore, the screen must often be cleaned. At this time, since the portion of the screen that needs to be cleaned is underwater, the work requires a lot of labor. Also, if the screen is clogged, there is a fibrous material such as hair, and the fibrous material is not easily removed because it is entangled with the screen. In particular, in a large-scale sewage treatment apparatus, since the screen is large and the number of the screens is large, the cleaning work of the screen requires much more labor.

[0008] An object of the present invention is to provide a fluidized bed type sewage treatment apparatus in which a microorganism-adhered carrier can be easily separated and maintenance is easy.

[0009]

In order to achieve the above object, an apparatus according to a first aspect of the present invention comprises an aeration tank provided with a diffuser and a mortar-shaped conical portion extending below a cylindrical portion. A carrier separation tank for separating the microorganism-adhered carrier in the treated water flowing from the aeration tank, and a tangential direction attached to the cylindrical portion of the carrier separation tank, which flows in from the aeration tank. A means for causing the treated water to flow into the carrier separation tank to form a vortex in the carrier separation tank, and a vortex generated by the means for forming the vortex to remove the microorganism-adhered carrier in the treated water collected at the bottom of the carrier separation tank. Means for extracting and returning it to the aeration tank.

[0010] In the apparatus according to the second invention, in the first invention, the carrier separation tank and the aeration tank are installed in communication with each other.
The treated water discharge pipe of the carrier separation tank is provided at a level lower than the water level at the time of operation of the aeration tank, so that a water level difference is formed between the aeration tank and the carrier separation tank. The water is configured to flow into the carrier separation tank.

According to a third aspect of the present invention, in the second aspect, the carrier separation tank is connected to a downstream end of the aeration tank.

According to a fourth aspect of the present invention, in the second aspect, the carrier separation tank is provided in the aeration tank.

In each of the above inventions, a carrier separation tank is provided, a vortex is formed in the tank, and the microorganism-adhered carrier is separated by a method of collecting solids at the center of the vortex. Easy to do. At this time, the treated water discharged from the aeration tank contains sludge in addition to the microorganism-attached carrier, and these solids are introduced together into the carrier separation tank, but the microorganism-attached carrier and the sludge are separated, Only the microorganism-adhered carrier is withdrawn. In other words, the microorganism-adhered carrier settles and is collected at the bottom of the carrier separation tank. Discharge.

Since there is a water level difference between the carrier separation tank and the aeration tank, the treated water is introduced at an inflow velocity capable of forming a vortex without using power.

[0015]

FIG. 1 is a plan view showing an example of an embodiment of a fluidized-bed sewage treatment apparatus of the present invention, and FIG.
FIG. 2 is a diagram showing a schematic cross section thereof. 1 and 2, 1 is an aeration tank, 2 is an aerator, and 40 is a microorganism-adhering carrier. In this apparatus, a carrier separation tank 1 for separating microorganism-attached carriers in treated water is provided downstream of the aeration tank 1.
0 is continuously provided.

The carrier separation tank 10 has the structure shown in FIG. 4, and is formed in a shape in which a mortar-shaped conical part is extended below a cylindrical part. In FIG. 4, reference numeral 11 denotes an inflow culvert, which is a means for introducing treated water from an aeration tank into a carrier separation tank to form a vortex, and is attached to a cylindrical portion of the carrier separation tank in a tangential direction. 13 is a submerged weir mounted so that the upper part is located on the water surface, 14 is a catchment basin for collecting treated water to be discharged, 15 is an overflow weir formed on the upper part of the catchment basin 14, and 16 is treated water discharge. A pipe 17 is a trap for collecting the floating matter and dropping it below the catchment basin 14, and 18 is an outlet for extracting a microorganism-adhering carrier.

In the apparatus shown in FIGS. 1 and 2 in which the carrier separation tank 10 having the above structure is installed, the inflow culvert 11 is connected through the side wall of the aeration tank 1, and the carrier separation tank 10 and the aeration tank 1 are connected to each other. Communicating. Further, the treated water discharge pipe 16 of the carrier separation tank 10 is provided at a level lower than the water level during the operation of the aeration tank 1. For this reason, the treated water in the aeration tank 1 flows into the carrier separation tank 10 due to a difference in water level. Further, since the inflow culvert 11 is connected in a tangential direction of the carrier separation tank 10, a vortex is formed in the carrier separation tank 10, and the microorganism-adhered carrier is collected at the center by the vortex, and accumulates at the bottom. I have. In the figure, reference numeral 12 denotes a valve for adjusting the flow rate of the treated water.

Reference numeral 19 denotes a carrier return pipe connecting the bottom of the carrier separation tank 10 and the aeration tank 1, 20 denotes a treated water pump for injecting treated water into the carrier return pipe 19, and 21 denotes a treated water discharge pipe. , 22 are treated water injection pipes, and the microorganism return carriers collected at the bottom of the carrier separation tank 10 are extracted by the carrier return pipe 19, the treated water pump 20, the treated water extraction pipe 21, and the treated water injection pipe 22. Means for returning to the aeration tank. The treated water injection pipe 22 has a distal end inserted into the carrier return pipe 19, and the inserted portion has a structure that performs the same operation as the eductor.

The sewage treatment by the apparatus having such a configuration is performed as follows. The sewage introduced into the aeration tank 1 is decomposed and purified by microorganisms in a tank in which air is blown from the diffuser 2 and the microorganism-adhering carrier is flowing. The treated water flows into the carrier separation tank 10 via the inflow culvert 11 together with the microorganism-adhering carrier and the suspended sludge. At this time, if necessary, the valve 12 is adjusted, and the inflow amount of the treated water and the flow speed thereof are appropriately set. Due to the inflow of the treated water, a vortex is formed in the carrier separation tank 10, and the microorganism-adhered carriers 40 are collected at the center of the vortex and accumulated at the bottom. If there is a microorganism-adhering carrier that has floated, the microorganism-adhering carrier is trapped together with the floating material in a trap 17.
And fall below the catchment basin 14 and settle and collect at the bottom. Microorganism-adhering carrier 4 accumulated at the bottom
Zero and solids are extracted and returned to the upstream side of the aeration tank 1 through the carrier return pipe 19.

At the time of returning the microorganism-adhered carrier 40, the treated water is injected into the carrier return pipe 19 by the treated water pump 20. And by the same action as the eductor,
The microorganism-adhered carrier 40 at the bottom of the carrier separation tank 10 is extracted and transported. When the microorganism-adhered carrier is transported by such a method, the occurrence of problems such as peeling of the biofilm adhered to the microorganism-adhered carrier and destruction of the carrier itself is minimized.

On the other hand, the treated water flows into the catchment basin 14 through the dive weir 13 together with the suspended sludge, and is sent from the treated water discharge pipe 16 to a sedimentation basin (not shown).

FIG. 3 is a sectional view showing another embodiment of the fluidized bed sewage treatment apparatus of the present invention. 3, the same reference numerals are given to the portions described in FIGS. 1, 2, and 4, and the description is omitted. In this embodiment, a carrier separation tank 10 is provided in an aeration tank. For this reason, there is an effect that the installation area can be reduced.

[0023]

According to the present invention, a carrier separation tank for generating a vortex is provided in the tank, and the microorganism-adhered carrier is separated by a method of collecting solids at the center of the vortex and collecting the solids at the bottom. Not easily done. Therefore, there is no need to perform operations such as cleaning, and maintenance and management of the apparatus is extremely easy.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of an embodiment according to a fluidized-bed sewage treatment apparatus of the present invention.

FIG. 2 is a schematic sectional view of the apparatus of FIG. 1;

FIG. 3 is a schematic cross-sectional view showing another embodiment of the fluidized bed sewage treatment apparatus of the present invention.

FIG. 4 is a view showing a structure of a carrier separation tank in FIGS. 1, 2 and 3;

FIG. 5 is a cross-sectional view showing an example of a conventional fluidized bed sewage treatment apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 aeration tank 2 diffuser 10 carrier separation tank 11 inflow culvert 12 valve 16 treated water discharge pipe 19 carrier return pipe 20 treated water pump 21 treated water drain pipe 22 treated water injection pipe 40 microorganism adhered carrier

Claims (4)

[Claims] 1. A microorganism-attached carrier is present in an aeration tank,
A fluidized-bed type sewage treatment system that blows air to biologically decompose organic substances in sewage, with an aeration tank equipped with an aerator and a mortar-shaped conical section below the cylindrical section. A carrier separation tank for separating the microorganism-adhered carrier in the treated water flowing from the aeration tank, and a tangential direction attached to the cylindrical portion of the carrier separation tank, which flows in from the aeration tank. A means for causing the treated water to flow into the carrier separation tank to form a vortex in the carrier separation tank, and a vortex generated by the means for forming the vortex to remove the microorganism-adhered carrier in the treated water collected at the bottom of the carrier separation tank. A fluidized bed sewage treatment apparatus, comprising: means for extracting and returning to an aeration tank. 2. A carrier separation tank and an aeration tank are provided in communication with each other, and a treated water discharge pipe of the carrier separation tank is provided at a level lower than a water level during operation of the aeration tank. The fluidized bed type sewage treatment apparatus according to claim 1, wherein a water level difference is formed between the fluidized bed and the water level difference, whereby the treated water in the aeration tank flows into the carrier separation tank. . 3. The fluidized bed sewage treatment apparatus according to claim 2, wherein the carrier separation tank is connected to a downstream end of the aeration tank. 4. The fluidized bed sewage treatment apparatus according to claim 2, wherein the carrier separation tank is provided in the aeration tank.