JPH0233440B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aeration device used for treating sewage including highly concentrated wastewater such as industrial wastewater and human urine.

Generally, wastewater such as sewage and wastewater is stored in an activated sludge aeration tank, and air is injected from an aeration device installed in the aeration tank to convert pollutants in the sewage that have adhered to the activated sludge into nutrients. Purification treatment is performed by absorbing and oxidizing the activated sludge.

FIG. 1 is a sectional view of such a conventional air diffuser. In the figure, 1 is an air diffuser, 2 is a porous plate in which many small holes 3 are formed, and 4 is a branch pipe, which communicates with an air supply pipe whose one end is connected to a compressor (not shown). The root portion 1a of the air diffuser 1 is incorporated into the hole 4a formed in the tube 4.

The small holes 3 of the porous plate 2 have a diameter of
Since it is relatively large at about 100 to 400 μm, it is easy for pollutants to enter the inside of the small hole 3 and cause clogging.
It had the disadvantage that it was likely to be impossible to reuse. Moreover, in order to prevent clogging, the air volume per unit area sent from the compressor to the porous plate 2 is
The air volume must be 100 ml/min·cm ² or more, and this air volume reduces the dispersion of air bubbles and requires a large compressor, which consumes a large amount of electricity, which is contrary to recent energy conservation efforts. Furthermore, under the air volume of 100 ml/min・cm ² or more, when air is diffused from the small hole 3, the air bubbles 5a coming out of one small hole and the air bubbles 5b coming out from another small hole adjacent to the small hole are separated. A so-called coalescence phenomenon in which large bubbles 5c are formed is likely to occur. When this bubbling phenomenon occurs, the ideal microbubbles cannot be generated, and the proportion of oxygen used to purify pollutants, that is, the oxygen dissolution efficiency, decreases and becomes less than 10% at most, making it difficult to carry out efficient wastewater treatment. Can not. In addition, since the porous plate 2 is formed in a single layer, the thickness of the porous plate must be made considerably thick in order to maintain durability and obtain fine bubbles, and as a result, the blower requires a large amount of thickness. This causes significant energy loss.

From the above, it is an object of the present invention to provide an air diffuser that can prevent clogging of the air diffuser, reduce power consumption, eliminate the bubbling phenomenon, and further reduce pressure loss while maintaining durability. purpose.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

Fig. 2 is a sectional front view of the sewage treatment equipment, Fig. 3 is a sectional side view of the aeration section according to the present invention, Fig. 4 is a sectional view showing the passage process of air in the aeration section, and Fig. 5 is for protection. It is a front view of the net.

In FIG. 2, 11 is an aeration tank.
Inside is a mixed liquid such as activated sludge and pollutant aqueous solution 1
2 are stored. Reference numeral 13 denotes an aeration device installed at the bottom of the aeration tank 11, through which air pressurized by a compressor 14 is sent under pressure through an air supply pipe 15. Note that the air that has been pressure-fed through the air supply pipe 15 reaches the air diffuser 18 via a collecting pipe 16 connected to the air pipe and a branch pipe 17 led out from the collecting pipe 16, and then reaches the air diffuser 18. The bubbles are injected from the surface into the mixed liquid 12.

FIG. 3 is an enlarged cross-sectional side view of the air diffuser according to the present invention. In the figure, the air diffuser 18 has a funnel-shaped cross section that opens upward, and a check valve 19 is provided at the base of the air diffuser 18. be. The check valve 19 is
Allowing air to flow in the direction of arrow A, but in the opposite direction
This is to prevent water flow from flowing in from the direction A', and is generally made of a rubber material or the like, and is biased in the direction of the arrow A' by a spring 20. Reference numeral 21 is a cap portion that holds a plurality of porous plates, which will be described later, inside the cap portion, and is provided so as to be screwable to the main body of the air diffuser 18, and a circular flange 22 is provided at one end. , a plurality of slip-off prevention members 23 are provided at the other end. 24 is a flat plate-shaped first porous body. The porous plate 24 is made of porous resin such as plastic, for example, after compression molding powder of thermoplastic resin such as polyamide resin, polyethylene resin, polypropylene resin, vinyl chloride resin, ACS resin, etc. into a flat plate shape, the compression molding is performed. The product is baked in an inert atmosphere such as nitrogen gas at about 250°C for about 30 minutes while still in the mold, and has numerous fine holes 24a as shown in Figure 4. 25 is a second porous plate disposed on the first porous plate 24. The second porous plate 25 is also manufactured in the same manner as the first porous plate 24, but the second porous plate 25 is made by mixing the resin powder before manufacturing with the first porous plate 25. It is made finer than the porous plate 24. The second porous plate 25 thus produced has numerous small holes 25a that are smaller than the first porous plate 24.

26 is a third porous plate disposed on the second porous plate 25;
It is a porous board. Although the porous plate 26 is manufactured in the same manner as the porous plates 24 and 25, the resin powder before manufacture is made finer than that of the second porous plate 25. Therefore, the third porous plate 26 has numerous small holes 26a that are smaller than the second porous plate 25. Reference numeral 27 denotes a nonwoven fabric made of a porous material disposed on the third porous plate 26, and one surface (diffusing surface) of the nonwoven fabric 27 is coated with a fluororesin film 28. In addition,
As shown in FIG. 4, the fluororesin film 28 is provided with countless small holes 28a of approximately 3 to 5 μm in size. 29 is a net for protecting the air diffuser surface, and this net is formed in a cross shape as shown in FIG. 5A. In addition, this net is shown in Figure 5 B,
As shown in FIG. 3, it may be provided in an I-shape in a circle.

Now, in order to install the above-mentioned porous plates 24, 25, 26 and non-woven fabric 27 inside the air diffuser 18, remove the cap part 21 from the main body, and sequentially install the net 29, non-woven fabric 27 on the flange 22 side of the cap part. , third,
The second porous plates 26 and 25 are stored, and finally the first
A porous plate 24 may be provided therein, and the plurality of slip-out prevention members 23 may be engaged with the porous plate 24. At this time, since the falling-off preventing members 23 have sloped surfaces that gradually protrude toward the flange 22, the porous plate can be easily attached and will not easily fall off. Thereafter, the cap portion 21 may be screwed onto the main body.

Then, the air conveyed from the branch pipe 17 presses the check valve 19, and the air chamber 18 of the air diffuser 18
a, and then each porous plate 24, 25,
26, the nonwoven fabric 27, and the fluororesin film 28, and are injected into the mixing plate 12 as a small bubble flow.

Therefore, to explain the state of the bubble flow using FIGS. 3 and 4, the air flowing into the air chamber 18a (FIG. 3) first flows through the first porous plate 2.
In the process of passing through the small hole 24a of No. 4, it becomes small bubbles. The air bubbles are formed in the small holes 25 of the second porous plate 25.
The bubbles are made even smaller by the small holes 26a of the third porous plate 26. Finally, it is sprayed from the small holes 28a of the nonwoven fabric 27 and the fluororesin film 28.
At this time, as the air bubbles pass through each of the porous plates 24, 25, and 26, they are gradually atomized, so that the air (air bubbles) has good dispersibility, and the air bubbles generate a coalescence phenomenon as in the conventional case. Never.

Further, even if the inflow of air into the air diffuser 18 (Fig. 3) is stopped, the pollutants adhering to the surface of the fluororesin membrane 28 will be removed due to the small holes 28a provided in the membrane 28 being very fine. Because there is no intrusion inside,
Does not cause clogging. Further, what enters the inside of the micropores is close to completely filtered fresh water, and this fresh water does not cause any trouble in the present air diffuser. Further, the pollutants attached to the membrane 28 are easily peeled off by the bubbles when the bubbles B are injected again.

As described above, according to the present invention, a porous membrane with a small pore size of 10 μm or less is provided, which functions to prevent the intrusion of pollutants present in the air diffuser tank, thereby eliminating the bubbling phenomenon and increasing power consumption. Therefore, it is possible to provide an aeration device that can perform wastewater treatment while increasing oxygen dissolution efficiency. Therefore, it is possible to generate extremely small microbubbles compared to the conventional example, and as a result, the air sent from the compressor can be used even at an air flow rate of 100ml/min・cm ² or less, which improves the dispersibility of the bubbles and improves the oxygen dissolution efficiency. It can bring about dramatic results that can more than double the amount. Further, even if the air flow into the air diffuser 18 is stopped, the pollutants 12 will not enter the air diffuser 18 because the small holes provided in the fluororesin membrane 28 are extremely fine. Furthermore, when the air bubbles O are again injected onto the pollutants adhering to the surface of the air diffuser, they can be easily peeled off due to their dispersibility, which has a great effect.

In addition, it completely eliminates the harmful effects caused by clogging and has excellent bubble dispersion properties, so it is extremely effective for treating highly concentrated wastewater such as human urine and industrial wastewater, and has great effects such as reducing power consumption. It has the following.

[Brief explanation of drawings]

FIG. 1 is a sectional side view showing a conventional example. 2 to 5 show one embodiment of the present invention, FIG. 2 is a sectional front view of the sewage treatment equipment, and FIG. 3 is a diffuser 18.
FIG. 4 is an enlarged sectional side view showing the passage of air, and FIG. 5 is a sectional side view of the main part showing the air passage process. In the figure, 13 is an air diffuser, 18 is an air diffuser,
24, 25, 26 are porous plates, 24a, 25a,
26a is a small hole, 27 is a nonwoven fabric, 28 is a fluororesin film, and 28a is a small hole.

Claims (1)

[Claims] 1. Air is forced into a diffuser section that includes a porous plate,
In the air diffuser which causes the air to pass through the small holes of the porous plate to generate fine bubbles from the air diffuser in the air diffuser tank, the air diffuser has a plurality of porous plates, The pore diameter of each of these porous plates is such that the average pore diameter of the porous plates arranged toward the air outflow side is smaller than the average pore diameter of the porous plates on the air inflow side, and these porous plates are arranged in order. The aeration surface side of the porous plate, which is arranged at intervals and located at the most extreme point on the air outflow side, has small pores with a diameter of 10 μm or less to prevent the entry of pollutants present in the aeration tank. An air diffuser characterized by being covered with a porous membrane. 2. The air diffuser according to claim 1, wherein the porous membrane on the air diffuser surface is formed of a nonwoven fabric and a fluororesin film covering the surface of the nonwoven fabric.