JPS60139394A - Biological treatment of waste water by employing fluidized bed - Google Patents

Abstract

PURPOSE:To eliminate the damage of particles and the abrasion of a pump, by allowing a part of waste water containing microorganism adhered grown particles to pass through the liquid cyclone on the recirculation line provided to the outside of a fluidized bed while taking out the same through said line. CONSTITUTION:Microorganism adhered particles grown by the propagation of microorganisms are floated above the interface 7 of a fluidized bed 2 and a solid-liquid separation zone 3. These particles are taken out of a tank along with a part of recirculated waste water through a recirculation line 5 and allowed to forcibly pass through the liquid cyclone 8 provided on the way of the recirculation line 5 by the sucking action of a recirculation pump 9 to peel off adhered microorganisms from grown particles mainly in the liquid cyclone 8. The particles are fallen into a precipitation type hermetically closed separation tank 11 and further fallen into a hermitically closed particle storage tank 14 through a falling pipe 13 under their own wt. and accumulated therein.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a fluidized bed biofilm process comprised of microbially attached particles.

A fluidized bed biofilm method is known, in which a fluidized bed is formed by particles to which microorganisms are attached, wastewater is treated within the fluidized bed, and the microorganism-adhered particles and treated water are separated above the fluidized bed.
In such a fluidized bed biological removal method, if the microorganisms attached to the particles grow and become too large, the particles will flow out of the treatment tank, so the excessively attached microorganisms must be peeled off from the particles. In this case, the conventional method has the following drawbacks.

(i) When particles are sucked through the pump, they are damaged and the pump is also worn.

(11) When attaching a stirrer to the upper part of the treatment tank and mechanically removing attached microorganisms, particle breakage and abrasion of the stirrer also occur.

The present invention was made with the aim of eliminating such conventional problems. Specifically, the present invention forms a fluidized bed in a treatment tank using particles to which microorganisms are attached, and treats wastewater within the fluidized bed. In a fluidized bed biological treatment method for wastewater that separates enlarged microorganism-adhered particles from treated water above the fluidized bed, a portion of the wastewater containing enlarged microorganism-adhered particles is passed from the top of the treatment tank through a circulation line installed outside the layer. While taking it out through
The adhering microorganisms are separated from the particles by passing through a liquid cyclone installed on the line, and the separated microorganism mixture from the upper outlet of the liquid cyclone is returned to the lower part of the processing tank through the circulation line, while the liquid from the main outlet is The particle mixture is subjected to solid-liquid separation in a closed settling type solid-liquid separation tank,
The separated liquid is combined with the liquid from the upper outlet of the hydrocyclone,
On the other hand, the sedimented particles are deposited in a closed particle storage tank, and after a predetermined amount of particles have been deposited in the storage tank, a part of the circulating fluid that has passed through the circulation pump is passed through the tank, and the sedimented particles are deposited in this tank. The present invention relates to a fluidized bed treatment method for wastewater, which is characterized in that wastewater is returned to the lower part of a treatment tank while being accompanied by wastewater.

The present invention will be described in detail below with reference to flow diagrams shown in the drawings.

In Figure 1, the wastewater treatment tank (1) has a fluidized bed zone (
2) and a solid-liquid separation zone (3) are formed. The fluidized bed is formed by adhering microorganisms to particles of sand, activated carbon, coke, anthracite, plastic, glass, silica gel, silica-alumina, etc. in advance and suspending them. The particle size of the particles for microbial adhesion varies depending on the material, but in the case of sand, which is optimal in terms of cost, ease of availability, ease of microbial adhesion, etc., it is usually about 0.1 to 3 a+m. Wastewater treatment tank (1)
The amount of particles that should be retained in the tank varies depending on the amount of microorganisms attached to the particles, but usually the sludge concentration in the tank (MLvSS)
It is preferable that the resistance is about 5000 to 4000 IIlΩ/Q. The wastewater flows from the supply line (4) to the circulation line (5).
), and in the treatment tank (1), the BOD components and/or nitrogen are added to the microorganism-adhered particles forming the fluidized bed while rising through the fluidized bed zone (2). components, and a part of them is also transferred to the solid-liquid separation zone (3
) and is taken out of the system as treated water through line (6). The microorganism-attached particles enlarged due to the production of microorganisms float above the interface (7) between the fluidized bed (2) and the solid-liquid separation zone (3), so they are circulated together with part of the recycled wastewater. It is taken out of the premises through the line (5) and forced to pass through the liquid cyclone (8) installed in the middle of the circulation line (5) by the suction action of the circulation pump (9) installed behind the cyclone (8). The attached microorganisms are separated from the manure particles mainly in the liquid cyclone (8). The liquid containing detached microorganisms rises to the upper part of the liquid cyclone (8), so it is returned to the lower part of the treatment tank (1) from the upper outlet through the circulation line (5), while the liquid containing the detached microorganisms rises to the upper part of the liquid cyclone (8). As particles fall to
This, along with some of the liquid, is lowered under its own weight from the lower outlet through the downcomer pipe (1o) into the sedimentation type sealed separation tank (11). In the separation tank (11), as the liquid rises within the premises, it is made to join the circulation line (5) behind the cyclone (8) through the line (12), while the particles descend within the tank. The particles are automatically lowered and deposited in a closed particle storage tank (14) through a downcomer pipe (13). After a predetermined amount of particles have accumulated in the reservoir tank (14), the downcomer pipe (14)
3) is closed to stop the automatic descent of particles, while a part of the circulating liquid after passing through the circulation pump (9) is sent to the reservoir tank (14) through the branch line (15).
) from the upper part to the lower part, and the deposited particles are entrained in this circulating liquid and returned to the lower part of the processing tank (1) via the downcomer pipe (16) and the circulation line (5). After returning the accumulated particles, close the valve (15a) of the branch line (15).
Then, the valve (16a) of the downcomer pipe (16) is closed to stop particle return, while the valve (13a) of the downcomer pipe (13) is opened to restart particle deposition. By repeatedly performing such a particle return operation, the particles can be regenerated and recycled. Valve (13a) in particle return operation
, (15a) and (16a) can be periodically performed by a combination of a solenoid valve and a timer.

In addition, for the purpose of increasing the amount of circulating fluid flowing through the reservoir tank (14), a constriction part (not shown) is installed in the middle of the circulation line (5) between the branch line (15) and the downcomer pipe (16). can be formed.

According to the treatment method of the present invention, the particles regenerated in the hydrocyclone (8) can be processed 4! without passing through the circulation pump (9) by making good use of a part of the circulating liquid. (1
), which eliminates problems such as particle damage and pump wear.

[Brief explanation of drawings]

FIG. 1 is a flow diagram showing one embodiment of the present invention, and FIG. 2 is an enlarged view of the main part of FIG. In the figure, (1) is a treatment tank, (2) is a fluidized bed zone,
(3) is a solid-liquid separation zone, (4) is a wastewater supply line,
(5) is a circulation line, (6) is a line, (7) is an interface,
(8) is a hydrocyclone, (9) is a circulation pump, (10
) is a downcomer, (11) is a solid-liquid separation tank, (12) is a line, (13) is a downcomer, (14) is a reservoir, (15) is a branch line, and (16) is a downcomer. (That's all) Figure 1 Figure 2

Claims (1)

[Claims] ■ Fluidized biological treatment of wastewater in which a fluidized bed is formed in the treatment tank using particles with microorganisms attached, the wastewater is treated in the fluidized bed, and the treated water is separated from the enlarged microorganism-adhered particles above the fluidized bed. In this method, a part of the wastewater containing enlarged microorganism-adhering particles is removed from the upper part of the treatment tank through a circulation line installed outside the layer, and the wastewater is passed through a liquid cyclone installed on the line, thereby removing the adhering microorganisms from the particles. The separated microorganism mixture from the upper outlet of the hydrocyclone is returned to the lower part of the treatment tank through the circulation line, while the particle mixture from the main outlet is separated into solid and liquid in a closed sedimentation type solid-liquid separation tank, and the separated microorganisms are separated into separated liquid. The particles are mixed with the liquid from the upper outlet of the hydrocyclone, while the sedimented particles are deposited in a closed particle reservoir, and after a predetermined amount of particles have accumulated in the reservoir, part of the circulating fluid after passing through the circulation pump is A fluidized bed treatment method for wastewater, characterized in that the wastewater is passed through a storage tank and returned to the lower part of the treatment tank while being accompanied by deposited particles.