JPS61271090A - Treating device for waste water using immobilized microorganism - Google Patents

Abstract

PURPOSE:To obtain a waste water treating device capable of removing BOD substance and turbid substance simultaneously generating only small amt. of excess sludge, and easy separation of solid from liquid and having high performance by packing pellets of immobilized microorganism suspending in water in a waste water treating device. CONSTITUTION:In a waste water treating device using pellets 3 comprising immobilized microorganism such as bacteria by entrapping with a high molecular material such as polyurethane, etc., pellets 3 comprising immobilized microorganism having <1 true specific gravity being suspended in water is used. Thus, the pellets are floated in water and gathered to the top of a treating tank 1 forming a filtration zone. Substances increasing SS and BOD are removed in the filtration zone, and a settling zone where substanced unadsorbed to the pellets relating to increase of SS or excess sludge are settled is formed below the filtration zone. As the result, the degree of generation of excess sludge is small, moreover, the separation of solid from liquid is facilitated. Thus, high performance of treatment is attained.

Description

[Detailed description of the invention] Main job is Retired Emperor and Duke! The present invention relates to a device for biologically treating organic and inorganic substances in wastewater, and particularly to a wastewater treatment device that generates a small amount of excess sludge.

The wastewater treatment method using blood-immobilized microorganisms has attracted attention because it has advantages such as generating a small amount of surplus sludge and being able to decompose recalcitrant organic matter (Kadono et al., ``Immobilization Methods''). "Sewage Reuse Technology Using Microorganisms," Collection of Abstracts from the 19th Research Presentation of the Japan Industrial Water Association, published in March 1982, and the specification of Japanese Patent Application No. 1526-1983).

Conventional equipment for carrying out this method consists of a wastewater treatment tank in which the immobilized microbial pellets are brought into contact with the wastewater, and a solid-liquid separation tank in which excess sludge is separated from the treated water.

Natural sedimentation separation and membrane separation are used for solid-liquid separation.

I'll do <7. However, in the above method, although the amount of surplus sludge generated is small, the sludge conversion rate (the amount of sludge generated per removed BOD) is 7 to 12%, and surplus sludge is generated. Also,
A large-scale solid-liquid separator is required to separate this excess sludge from treated water. Therefore, it is desired to develop a treatment method and device that generates less surplus sludge and facilitates solid-liquid separation.

Therefore, the present invention overcomes the drawbacks of the prior art mentioned above and provides B.
It is an object of the present invention to provide a wastewater treatment device that can remove turbidity at the same time as OD removal, generate a small amount of surplus sludge, facilitate solid-liquid separation, and have high treatment performance.

In the present invention, a pellet having a true specific gravity of less than 1 and floating in water is used as an immobilized microorganism pellet, and a settling zone is formed below a two-layer zone formed by the pellet in water. , - a water supply pipe to be treated below the filtration zone;
The above problem is solved by providing a treated water discharge pipe above.

That is, the wastewater treatment apparatus according to the present invention is characterized in that it is filled with immobilized microorganism pellets that have a true specific gravity of less than 1 and float in water.

The microorganisms to be immobilized in the present invention may be pure cultures or mixed cultures of any microorganisms such as bacteria, actinomycetes, molds, and yeasts, or microorganisms attached to activated sludge or soil.

In the present invention, the immobilizing materials include polyurethane, polyacrylamide, calcium alginate, carrageenan, methoxytetraethylene glycol methacrylate, 2,2-bis[4-(methacryloxypolyethoxy)]
-Phenyl]-propane, polyethylene glycol diacrylate, polypropylene glycol diacrylate, or other known immobilization material, carbon dioxide gas,
It is possible to use a material mixed with fine bubbles of nitrogen gas or the like or fine pieces of expanded polystyrene.

The immobilized microorganism pellet used in the present invention is produced by comprehensively immobilizing microorganisms on the above-mentioned immobilization material using a conventional method, and has a cylindrical or spherical shape, and has an equivalent sphere diameter in the range of 0.5 to 10 mm. It is preferable to select the particle size within the range.

According to the present invention, when the immobilized microorganism pellets having a true specific gravity of less than 1 are filled, the pellets float in the water and collect at the upper part of the treatment tank, forming an overflow zone. This permeable zone acts to remove SS and BOD. Below the filtration zone, a settling zone is formed in which SS and excess sludge that do not adhere to the pellets settle. That is, biological treatment of wastewater and solid-liquid separation are performed simultaneously in one treatment tank.

In the treatment of wastewater using immobilized microorganisms, the possible causes of excess sludge are (1) leakage of microorganisms from pellets of immobilized microorganisms, and (2) growth of floating bacteria. In the present invention, excess sludge generated due to (1) is stored in the f-filtration zone. is passed through and adheres to the pellet,
The attached sludge will self-extinguish. A part of the surplus sludge generated due to the cause of (2) is passed through the trough zone, and a part of it settles into the settling zone. Therefore, the amount of surplus sludge generated is reduced.

1 algae■ Next, the present invention will be explained in detail based on the drawings.

FIG. 1 is a schematic cross-sectional view of a wastewater treatment device showing one embodiment of the present invention. In FIG. 1, the inside of a wastewater treatment tank 1 is filled with immobilized microorganism pellets whose true specific gravity is less than 1, and when water is introduced, an immobilized microorganism pellet layer 3 is formed under a wire mesh 2. is formed. At the top of the tank,
A treated water discharge pipe 4 and a wash water supply pipe 5 are provided, and a wash water discharge pipe 6 is provided at the bottom of the tank. Further, below the immobilized microorganism pellet layer 3, a waste water supply pipe 7 was provided in the middle of the tank.

When treating wastewater using this treatment device, the wastewater is supplied from the wastewater supply pipe 7 to the wastewater treatment tank 1, and first, turbid substances with a high sedimentation rate are sedimented and removed in the sedimentation zone, and then the floating solids are removed. By passing the wastewater through the filtration zone of the microorganism pellet layer 3 in an upward flow, the BOD components of the wastewater are removed, and at the same time, turbidity is removed, and the wastewater is discharged through the treated water discharge pipe 4 to the outside of the apparatus. The treatment process generally ends when the turbidity concentration of the treated water reaches an acceptable limit, and then the cleaning process begins.

In the cleaning process, cleaning water is introduced into the device from the cleaning water supply pipe 5, and the immobilized microorganism pellet layer 3 is vibrated and stirred to separate the captured suspended solids from the pellets, and at the same time, the cleaning water is passed through in a downward flow. It is entrained in water, enters the settling zone, and is discharged from the washing water discharge pipe 6 together with the settled turbidity to the outside of the apparatus. The feature of this cleaning method is that the washing water flows in a downward flow direction, which is the same direction as the sedimentation direction of suspended matter, and the amount of washing water used is smaller than that in an upward flow washing method. Furthermore, in the case of downward flow, the floating immobilized microorganism pellets are effectively vibrated and stirred. Furthermore,
Since the suspended solids deposited in the settling zone are discharged by the washing water of the immobilized microorganism pellet layer, new washing water is unnecessary.

FIG. 2 shows an embodiment in which an aeration section 8 is provided in the wastewater treatment tank 1. Wastewater is supplied from above the aeration section 8, and an air supply pipe 9 is installed below the aeration section 8.

In this embodiment, the wastewater is aerated and then purified and filtered through a layer 3 of immobilized microorganism pellets.

FIG. 3 shows an embodiment in which the aeration section 8 is also filled with immobilized microorganism pellets having a true specific gravity of less than 1, and the processing efficiency is better than that of the apparatus shown in FIG. 2.

Figure 4 shows a wire mesh attached to the bottom of the aeration section 8.
An embodiment is shown in which immobilized microorganism pellets 11 having a true specific gravity of more than 1 are filled in the container. In this embodiment, the aeration section 8
A traverse is also carried out in the immobilized microbial pellet layer within.

Example 1 Activated sludge from a sewage treatment plant was concentrated to an MLS of 320,000 μ/l in Bere. This concentrated activated sludge has polyethylene glycol and polypropylene glycol as main chains, and molecules ii40
00 to 5000, 8% of urethane prepolymer having isocyanate groups at both ends was added, polymerized, and the diameter was 1.
．． It was molded into 5fi pellets. The true specific gravity of the obtained pellets was 0.98.

The pellets obtained in 11 plates of Leprosy were placed in the wastewater treatment tank 1 shown in Figure 1 for 30 minutes.
% filling rate.

When food wastewater with a BOD of 54-65 .mu./1.5S23-35 .mu./l was continuously treated for 20 days with a residence time of 15 minutes, treated water with a BOD of 8-12 .mu./1ss3.mu./1 or less was obtained.

The SS discharged from the wash water discharge pipe 6 is treated as surplus sludge, and B
The sludge conversion rate is calculated from the OD treatment amount using the following formula: 5~
It was 8%.

When the activated sludge method was used as a conventional method, the sludge conversion rate was 40 to 53%.

As described above, according to the treatment apparatus of the present invention, the amount of surplus sludge generated is small, solid-liquid separation is easy, and high treatment performance is achieved. Furthermore, according to the present invention, biological treatment and solid-liquid separation of wastewater are performed in one treatment tank, making it unnecessary to provide a separate solid-liquid separation tank.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a waste water treatment device showing one embodiment of the present invention, FIG. 2 is a schematic cross-sectional view of a waste water treatment device showing another embodiment of the present invention, and FIG. 4 is a schematic sectional view of a wastewater treatment device showing another embodiment of the present invention, and FIG.
FIG. 2 is a schematic cross-sectional view of a wastewater treatment device showing another embodiment of the present invention.

Claims (4)

[Claims] (1) In a wastewater treatment device using immobilized microorganism pellets in which microorganisms are encased and immobilized in a polymeric substance, the immobilized microorganism pellets are filled with immobilized microorganism pellets that have a true specific gravity of less than 1 and float in water. A wastewater treatment device using immobilized microorganisms, comprising: (2) A treated water supply pipe and a washing wastewater discharge pipe are provided below the filtration zone formed by the immobilized microbial pellets floating in the water, and a treated water discharge pipe and a washing water supply pipe are provided above the filtration zone. A wastewater treatment device according to claim 1. (3) The wastewater treatment device according to claim 1 or 2, wherein an aeration section is provided in the device, and an oxygen supply device is provided at a lower part of the aeration section. (4) The wastewater treatment device according to claim 1, 2 or 3, wherein the aeration section is also filled with immobilized microorganisms.