JPS62121697A - Treatment of waste water by fluidized bed - Google Patents

Abstract

PURPOSE:To well perform the release of adhered microorganisms from particles, by arranging a static mixer between treated water and a liquid cyclone and passing waste water preliminarily mixed with air through the static mixer. CONSTITUTION:Waste water is supplied to a treatment tank from a line 13 along with a recirculation liquid passing through a recirculation line 5. Waste water rises through a fluidized bed zone 2 in the treatment tank 1 and, during this time, a BOD component and a nitrogen component are given to microorganisms adhered particles. Grown particles with adhered microorganisms float to the interface of the fluidized bed zone 2 and a solid-liquid separation zone 3 and are taken out of the tank through the recirculation line 5 along with a part of recirculated waste water to be passed through a static mixer 4 from a line 14 in a state mixed with air. Waste water is violently stirred to perform the release of adhered microorganisms from particles. By this method, release can be efficiently performed.

Description

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

A fluidized bed biofilm method is known in which a fluidized bed is formed with 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 the particles are drawn through the pump,
The particles are damaged and the pump is also worn out.

(i) If a stirrer is attached to the top of the treatment tank and attached microorganisms are mechanically removed, multi-particle breakage and abrasion of the stirrer may occur.

The inventors of the present invention have repeatedly conducted various studies to eliminate the drawbacks of the prior art as described above, and have found that by using a liquid cyclone as a means to remove attached microorganisms from particles, the objective can be almost achieved. They discovered this and have already filed a patent application (Japanese Unexamined Patent Publication No. 139394/1983). This prior invention by the present inventors is an excellent invention with practicality, but it also has an alkaline agent that is used to more efficiently separate particles from attached microorganisms and to adjust the amount of water circulating in the treatment system. If the amount used can be reduced, its usefulness will be further improved.

Means for Solving the Problems In view of the above-mentioned current situation, the present inventor has conducted research to further improve and develop the above-mentioned prior invention. If wastewater mixed with air is passed through the static tank, particles and attached microorganisms can be separated more effectively, and the alkaline agent can be used more easily. It was also found that there was a significant decrease in That is, the present invention relates to the following wastewater treatment method.

[A fluidized bed treatment method for wastewater in which a fluidized bed is formed in a treatment tank using particles to which microorganisms are attached, the wastewater is treated in the fluidized bed, and the enlarged microorganism-adhered particles are separated from the treated water above the fluidized bed. In this method, a part of the wastewater containing enlarged microorganism-adhering particles is taken out from the upper part of the treatment tank through a circulation line installed outside the layer, and air is mixed with the taken out wastewater. The attached microorganisms are separated from the particles by sequentially passing through the liquid cyclone and the liquid cyclone, and the mixed gas is dissipated from the upper opening of the liquid cyclone, and the separated microorganism mixture from the upper outlet of the liquid cyclone is processed through a circulation line. The particle mixture from the bottom outlet is returned to the bottom of the tank, while the particle mixture from the bottom outlet is sent to the circulation tank.
) in the treatment tank y together with a part of the circulating fluid after passing through λ■l.
T! A fluidized bed treatment method for wastewater, characterized in that the wastewater is returned to the rs. '' The present invention will be described in detail below with reference to the F-17 frame shown in the drawings.

In Figure 1, the wastewater treatment tank (fluidized bed lean)
2) and solid-liquid separation lean (3) are formed.

In the fluidized bed, microorganisms are added in advance to sand, activated carbon, coke, anthracite, plastic, glass, silica gel, silica-aluminum! It is formed by adhering to particles such as grass and floating turtles. The particle size of the particles for attaching microorganisms varies depending on the material, the size of the treatment tank (1), the type of wastewater raw water, etc., but it depends on cost, ease of acquisition,
In the case of sand, which is optimal in terms of ease of adhesion of microorganisms, the length is usually about 0.1 to 3 m. Wastewater treatment # (1) The amount of particles to be retained in the tank varies depending on the adhesion of microorganisms to the particles, but usually when the sludge concentration in the tank (MLVSS) is 1000
It is preferable to set it to about 0 to 15,000 capes/l. The wastewater is supplied from the supply line (2) into the treatment tank (1) together with the circulating liquid that passes through the circulation line (5).
In the fluidized bed, the BOD component and/or nitrogen component is given to the microorganism-adhered particles forming the fluidized bed while rising through the solid-liquid separation lean (I(2)). 3) It rises inside and is taken out from the line (6) as treated water. Microorganism-attached particles enlarged due to the growth of microorganisms are transferred to the fluidized bed (2) and solid-liquid separation leak (3).
This floats to the surface at the interface (7) with the wastewater, so it is taken out of the layer through the circulation line (5) along with a part of the recycled wastewater, and statically mixed with air from the line α. - Pass through (4). The wastewater whose speed has been increased (due to the mixing of air) is vigorously agitated by the spiral motion within the static mixer (4), and particles and attached microorganisms are separated. The wastewater that has exited the static mixer (4) continues to flow through the liquid cyclone (8) placed in the middle of the circulation line (5) and into the circulation pump (9) installed behind the cyclone (8). The suction action forces the particles to pass through, further promoting the detachment of attached microorganisms from the enlarged particles. The air mixed with the wastewater is released into the atmosphere from the upper opening of the liquid cyclone (8), accompanied by the carbon dioxide gas that had been dissolved in the wastewater, so that the circulating water and the wastewater treatment tank (1 ) The amount of neutralizing agent used to properly adjust the PLF of the liquid in the tank is reduced. To the top of the liquid cyclone (8),
As the liquid containing the detached microorganisms rises, it is returned to the lower part of the treatment tank (1) from the upper outlet through the circulation line (5). On the other hand, since particles fall to the lower part of the liquid suction line (8), a part of the circulating liquid passing through the circulation line (5) is sent to the water ejector (12) via the branch 5-in0υ.
5-The particles in the liquid cyclone (8) are removed by suction from the OQ and returned to the lower part of the wastewater treatment tank (1) together with the branch circulating liquid. By repeating this operation of returning the particles, the particles are removed. Recycle and use while regenerating.

The alkaline agent can be added at any point, such as to the circulating water in the circulation line (5) or to the treated water in the wastewater treatment tank (1). Wastewater treatment tank (1)
Supply of oxygen or oxygen-containing waste to maintain aerobic conditions within the chamber can also be carried out at any point such as the circulation line (5).

According to the present invention, the following effects are achieved.

(i) Microorganisms can be efficiently separated from microorganism-adhered particles. Incidentally, as an example, in the flow diagram shown in Fig. 1, the microbial removal rate when oxygen is not supplied from the line (14) and the static mixer (4) is not used is about 10% at maximum. In contrast, in the case of the present invention, it was 30% or more.

(i) Since the carbon dioxide scum contained in the liquid discharged from the treatment tank is effectively removed, the amount of alkaline agent used for neutralization is greatly reduced. Incidentally, as an example, the foo-4 shown in FIG.
In case of aerating the treated water using an independent aeration device without mixing air in the line αΦ, the amount of Na 0 for neutralization is about 5 times that of the method of the present invention.
11 was required.

(ii) As a result of (i) and (i) above, construction costs, operating costs, etc. are significantly reduced, and the space required for equipment is also reduced.

[Brief explanation of drawings]

FIG. 1 is a flow chart showing a part l111i aspect of the present invention.
I? It's a crumb. (1)...Treatment tank, (2)...Fluidized bed lean, (3
)...Solid-liquid separation unit, (4)...Static mixer, (5)...Circulation line, (6)...Treated wood removal line, (8)--- Fluid cyclone, (9
)---Circulating type: J'JJSa1)... Branch line, (6)... Water ejector, θ1... Waste water supply line. (That's all) Agent: Eiji Saegusa, patent attorney 9.・4-
−;j

Claims (1)

[Claims] (1) A fluidized bed of wastewater is formed by particles to which microorganisms are attached in a treatment tank, the wastewater is treated in the fluidized bed, and the enlarged particles with microorganisms are separated from the treated water above the fluidized bed. In the treatment method, a part of the wastewater containing enlarged particles attached to microorganisms is taken out from the upper part of the treatment tank through a circulation line installed outside the layer, and air is mixed with the taken out wastewater, and a static mixer installed on the line is used. By sequentially passing through the liquid cyclone, the attached microorganisms are separated from the particles, the mixed gas is dissipated from the upper opening of the liquid cyclone, and the separated microorganism mixture from the upper outlet of the liquid cyclone is passed through a circulation line to the lower part of the processing tank. A fluidized bed treatment method for wastewater, characterized in that the particle mixture liquid from the lower outlet is returned to the lower part of the treatment tank together with a part of the circulating liquid after passing through a circulation pump.