JPS5938834B2 - Rotating disc type activated sludge equipment - Google Patents

Description

Detailed Description of the Invention The present invention aims to prevent activated sludge from falling off the disc, improve treatment capacity, and reduce excess sludge in water treatment using a rotating disc contact device. It is characterized by making it possible to supply gas to the sludge from the surface of the disk.

Activated sludge treatment using the rotating disk method has low power costs, a large amount of microorganisms attached to the disk, a low food to microorganism ratio, and a high level of purification with extremely short contact times. It is also used for secondary and tertiary treatment of wastewater because it produces less sludge compared to other methods.

However, as it has been used in a wide range of fields for a long time, its shortcomings have begun to become noticeable.

One of the major disadvantages is that there are many microorganisms attached to the disc, which is also an advantage.ζ On the other hand, as the microbial layer attached to the disc increases in thickness, it is necessary to aerate the disc sufficiently even after it is exposed to the atmosphere. Instead, microorganisms near the disk surface die and fall off the disk surface.

As a result, not only is a large amount of sludge produced in the septic tank, but it also takes several days or weeks for microorganisms to re-adhere to the disks where they have fallen off, and during this time, the processing capacity is significantly reduced. descend.

The major advantage of the rotating disk method is that it produces less surplus sludge than other activated sludge methods, but as it comes to be used in urban sewage treatment, cafeterias, pig farms, and other businesses close to urban areas, It is desirable to further reduce excess sludge and downsize the equipment.

As a result of intensive studies by the present inventors to solve these problems, it is basically necessary to solve the lack of oxygen or lack of nutrients for the microorganisms inside the layer of microorganisms attached to the disk. This discovery led to the present invention.

Examples of the present invention will be described below based on the drawings, but the present invention is not limited only to the examples.

Figure 1 shows a contact device incorporating a conventional flat plate rotating body.
1 is a processing tank, 2 is a rotating disk, and 3 is a cover.

FIG. 2 shows an overview of a rotating disk device based on the present invention.

That is, on the rotating disk 2, a hollow fiber bundle 4, which is a hollow object through which gas can pass, and which has pores on its outer surface through which gas can pass, is arranged, and both ends of the hollow fiber bundle 4 are arranged. is connected to the distribution pipe 8 installed on the rotating disk 2,
Each distribution pipe is connected to a hollow thick-walled rotating shaft 5.

Oxygen or a gas containing oxygen is sent to the rotating shaft 5 through the air supply pipe 7, through the rotary joint 6, through the distribution pipe 8, to the hollow fiber bundle 4, and from its surface as fine gas bubbles to the rotating plate. Supplied to the activated sludge above.

To connect the distribution tube 8 and the hollow fiber bundle 4, the ends are concentrated with adhesive and fixed to the base 9 as shown in FIG.

In addition, in order to utilize the surface area of the hollow fibers more effectively, the hollow fiber bundles 4 are spread out on a flat plate and the ends are joined with adhesive, as shown in Figures 5 and 6.
It is also possible to attach the hollow fiber support frame 11 to the distribution pipe 8 and fix it with bolts 12.

As shown in FIG. 3, the distribution pipe 8 distributes and supplies the gas sent from the air supply pipe to the hollow fiber bundle 4, and is connected to a hollow rotary shirt 5.

In order to send gas to the sludge adhering to the rotating disk, a flat gas-permeable membrane may be used in addition to the method using the hollow fiber bundle shown in the above embodiment.

An example of this will be described with reference to the drawings.

FIG. 7 shows an external view of the rotating disk activated sludge method based on the present invention.

Reference numeral 15 indicates a gas-permeable membrane holding plate, and 16 indicates a gas-permeable membrane.

The gas is sent through the air pipe I to the hollow rotating shaft 5 and into the rotating disk.

The air inside the disk will be blown out from both surfaces of the disk.

The surface of the membrane is held down by the holding plate 15, and the activated sludge grows on the support and the membrane, so that gas is directly supplied into the activated sludge.

FIG. 8 shows a side view of the disk, and FIG. 9 shows a plan view.

As shown in FIG. 8, gas is sent into the inside of the disc through the air pipes of the rotating shafts 5 to 19.

Insert the upper part of the disk 17 and tighten the bolt nut 18
The membrane is tightened so that the gas has no escape other than the membrane.

The holding plate that presses down the disc surface may be designed to utilize the surface of the gas-permeable membrane as widely as possible and to have the strength of the disc, for example, a board with many holes as shown in Fig. 9. etc. are used.

FIG. 10 shows an embodiment of a rotating disk device in which hollow fibers are uniformly arranged on a disk.

By doing so, it becomes possible to make the sludge adhere to the disk uniformly and further improve the treatment effect.

In FIG. 10, 23 indicates a hollow fiber, and 2 indicates a rotating disk.

Reference numeral 25 indicates an end of a hollow fiber hardened with resin, and this is placed inside a spacer 26 on the rotating shaft 5.

The gas sent through the rotating shaft 5 is sent to the hollow fibers 22 through the ventilation holes 19.

Gas is blown out from the surface of the hollow fibers through micropores and supplied to the activated sludge.

FIG. 11 shows a plan view of the rotating disk 2. As shown in FIG.

The hollow fibers 23 are arranged on one surface of the rotating disk along the radial direction of the disk.

It is preferable for the hollow fibers used in the present invention to have a small pressure drop with respect to the passage of gas. On the other hand, it is desirable that the practical surface area is large, and for this purpose, the fibers should have an outer diameter of 500 microfron to 1 millitorr. preferable.

Porous hollow fibers or flat membranes can be obtained by known methods.

For example, by cold-stretching and heat-treating a crystalline polymer, it is possible to create a porous structure having pores with diameters of several 100 to several 1000 pores.

It can also be obtained by adding a second component and stretching.

Crystalline polymers include polyethylene, polypropylene, polyvinyl chloride, polyester, nylon, polyfluorinated ethylene, etc., but materials that are hydrophobic or close to hydrophobic, such as having a contact angle with water of 85° or more, are preferable. .

Polyethylene, polypropylene, polyfluorinated ethylene, etc. are suitable for this purpose.

Being hydrophobic makes it difficult for water to penetrate inside the hollow fibers, making it possible to lower the air pressure, and at the same time, preventing performance deterioration due to the growth of bacteria inside the hollow fibers.

Although it is obvious, nylon or acrylic fibers, which are hydrophilic materials, may be surface-treated to make them hydrophobic.

The pore size of the porous body should preferably be such that bacteria and fungi do not invade inside, supply gas to the extent that there is no pressure loss, and do not cause sludge to be mechanically separated as a large air flow. It is desirable that the diameter is 100 to 100 people.

When using a film-like membrane, similar to hollow fibers, ICC glycylene, polypropylene, polyfluorinated ethylene, etc. are preferable, and it is desirable that the contact angle with water is 85° or more.

Being hydrophobic prevents water from entering the disc, preventing internal rot, preventing clogging of ventilation pipes, and keeping ventilation pressure low.

In order to maintain the mechanical strength of the flat membrane, it is also possible to use a laminated support with non-woven fabric or net-like material.

As described above, by making ventilation possible on the rotating disk and supplying a small amount of oxygen or a gas containing oxygen to activated sludge, the treatment capacity of activated sludge can be improved, and the treatment capacity of activated sludge can be improved by almost 3 times.
More importantly, the excess sludge is almost eliminated and the activated sludge adhering to the disks is prevented from falling off.

On the other hand, the pressure of the gas to be sent is about 0.1 to 1.0 atm, which is sufficient, and the amount of electric power required for this is also small.

As the capacity of the device improves, it becomes possible to downsize the device, and if a surplus sludge treatment unit is also included, the cost of treating activated sludge will be significantly reduced.

[Brief explanation of the drawing]

Fig. 1 shows an activated sludge device incorporating a conventional flat plate rotor, Fig. 2 shows an activated sludge device incorporating the hollow fiber bundle of the present invention, Fig. 3 is a side view of Fig. 2, and Fig. 4 shows an activated sludge device incorporating a conventional flat plate rotating body. A detailed view of the installation of the hollow fiber bundle, FIG. 5 is a sectional view when the hollow fibers are arranged in one row, and FIG. 6 is a plan view of FIG. 5. Figure 7 is an external view of a rotating disk activated sludge device using a gas-permeable flat membrane, Figure 8 is a sectional view of the same, Figure 9 is a side view of the same, and Figure 1 is a side view of the same.
Figure 0 is a cross-sectional view of another example of a rotating disk using hollow fibers.
FIG. 11 is a side view of the same. In the drawings, 1 is a treatment tank, 2 is a rotating body, 3 is a cover, 4 is a hollow fiber bundle, 5 is a hollow roller, 8 is a distribution pipe, 15 is a membrane holding plate,
17 is a spacer, and 23 is a hollow fiber.

Claims (1)

[Scope of Claims] 1. A rotating disk type activated sludge device in which one or more rotating disks are attached to a rotating shaft so that air can be blown outward from a microporous membrane provided on the surface. 2. The rotating disk type activated sludge device according to claim 1, wherein the rotating shaft is not hollow and also serves as an air pipe. 3. The rotating disk type activated sludge apparatus according to claim 1 or 2, wherein the microporous membrane is made of hollow fibers. 4. The rotating disk type activated sludge apparatus according to claim 3, wherein the hollow fibers are made of a material having a contact angle with water of 85 degrees or more. 5. The rotating disk type activated sludge apparatus according to claim 1 or 2, wherein the microporous membrane is in the form of a film sheet. 6 The contact angle of porous film or sheet with water is 85°
The rotating disk type activated sludge apparatus according to claim 5, which is made of the above-mentioned materials.