JP2001269688A - Drain cleaning device using floating filter medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drain cleaning device using a floating filter medium capable of reducing backwashing frequency than that in conventional one and capable of preventing the activity deterioration of bacteria body due to the backwashing. SOLUTION: A granular floating filter medium 2 carrying a biological membrane is packed in a tank, and a drain is passed in upflow from the lower part of the tank while diffusing air by a middle step air diffusing means 3 of a packed layer. The part lower than the air diffusing means 3 becomes a denitrifying part 6 and the part above the air diffusing means 3 becomes a nitrifying part 7, and a floating filter medium 2a at the denitrifying part 6 is made of a material having larger particle size and larger specific gravity than that of the floating filter medium 2b at the nitrifying part 7. Since filtering resistance becomes low and suspended substance capturing capacity becomes large, the backwashing frequency is reduced. Since the floating filter medium 2a and 2b return to an original place, the activity deterioration of the bacteria body can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a waste water purifying apparatus using a floating filter.

[0002]

2. Description of the Related Art As a wastewater purifying apparatus capable of performing nitrification and denitrification in one tank, a wastewater purifying apparatus using a floating filter material as shown in FIG. 2 is known.
In this apparatus, a tank 1 is filled with a floating filter medium 2 made of expanded polystyrene or the like having a uniform particle size, a biofilm is supported on the surface thereof, and air is diffused from an air diffusion means 3 in a middle stage of the packed layer. Of structure. The drainage is passed upward through the raw water supply pipe 4 into the tank 1 from the lower part of the tank, taken out from the upper end of the tank 1 as treated water, and part of the treated water is returned to the tank bottom by the return pipe 5. .

[0003] Since oxygen is not supplied to the lower part of the diffusing means 3, the lower part of the packed bed becomes an anaerobic denitrification part 6, and conversely, sufficient oxygen is supplied to the upper part of the diffusing means 3. Therefore, the upper part of the packed bed becomes the aerobic nitrification part 7. For this reason, nitrate nitrogen in the wastewater flowing into the denitrification section 6 from the lower part of the tank is converted into nitrogen gas by the denitrifying bacteria and removed from the water, and the BOD component is also removed. Also in the drainage
s is also captured and removed by the floating filter medium 2 below the packed bed. Next, the wastewater flows into the nitrification section 7 at the upper part of the packed bed, the ammonia nitrogen in the wastewater is converted into nitrate nitrogen by the nitrifying bacteria, and the BOD component remaining by the denitrification reaction is removed. Part of the treated water containing nitrate nitrogen is sent again to the denitrification section 6 by the return pipe 5, and the nitrification denitrification by the nitrification liquid circulation method is performed. A perforated plate 9 is provided in the upper part of the tank so that the floating filter medium 2 does not flow out.

However, in such a wastewater purifying apparatus, ss in the wastewater is caught by the floating filter medium 2 at the lower part of the packed bed and the filtration resistance increases, so that backwashing must be performed. There was a problem that drainage occurred. In addition, when the backwash is performed, the floating filter medium 2 in the denitrification section 6 and the floating filter medium 2 in the nitrification section 7 are replaced by the backwash because the floating filter medium 2 in the entire tank is vigorously stirred. However, there is a problem that the biological activities of the denitrifying bacteria and nitrifying bacteria adhering to the floating filter medium 2 decrease with this environmental change.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems in the prior art, can reduce the frequency of backwashing, and reduce the biological activity of denitrifying bacteria and nitrifying bacteria by backwashing. The purpose of the present invention is to provide a wastewater purifying apparatus using a floating filter medium having a low density.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention fills a tank with a particulate floating filter medium carrying a biofilm and diffuses the medium through an air diffuser in the middle stage of the packed bed. In a wastewater purification device that drains wastewater in an upward flow from the lower part of the tank, the floating filter material in the denitrification section below the diffuser is
It is characterized in that it has a larger particle size and a higher specific gravity than the floating filter medium in the nitrification section above the diffuser. The particle size of the floating filter medium in the denitrification part is 4.0 to 5.0 m.
m, the particle size of the floating filter medium in the nitrification section is 3.0-4.5 mm, the specific gravity of the former is 0.05-0.08, and the specific gravity of the latter is 0.035-0.065.
It is preferable that

In the waste water purifying apparatus of the present invention, the floating filter medium in the denitrification section has a larger particle size than the floating filter medium in the nitrification section. Since the filtration resistance of the whole layer can be reduced and the amount of ss that can be trapped increases, clogging of the floating filter medium hardly occurs. Also, because the floating filter medium in the lower denitrification section has a higher specific gravity than the floating filter medium in the upper nitrification section, even if the entire floating filter medium in the tank mixes during backwashing, the floating filter medium will reappear due to the difference in specific gravity. Easy to separate as before. Therefore, it is possible to prevent the activity of the denitrifying bacteria and the nitrifying bacteria from decreasing.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below. FIG. 1 is a sectional view showing an embodiment of the present invention,
Inside the tank 1 having a perforated plate 9 on top, a granular floating medium 2
The configuration in which the air diffuser 3 is provided in the middle stage of the packed bed is the same as that of the conventional wastewater purification device shown in FIG. Drainage is introduced from the raw water supply pipe 4 at the lower part of the tank, and the treated water is taken out from above the perforated plate 9 through the tank 1 as an upward flow, and a part of the treated water is again returned to the lower part of the tank by the return pipe 5. Is also the same as the conventional waste water purification device shown in FIG. The packed bed below the diffuser 3 is an anaerobic denitrification section 6, and the packed bed above the diffuser 3 is an aerobic nitrification section 7 to perform nitrification denitrification by a nitrification liquid circulation system. Will be

However, in the conventional wastewater purifying apparatus, the floating filter medium 2 having a uniform particle size is filled in the entire tank,
In the present invention, as shown in FIG. 1, the floating filter medium 2a of the denitrification section 6 below the diffuser 3 has a larger particle size than the floating filter medium 2b of the nitrification section 7 above the diffuser. It has a large specific gravity. Each of these floating media 2a and 2b is made of expanded polystyrene. Denitrification part 6
The particle diameter of the floating filter medium 2a of the nitrification unit 7 is preferably 3.0 to 4.5 mm while the particle diameter of the floating filter medium 2a is 4.0 to 5.0 mm, and the specific gravity of the floating filter medium 2a is 0.05 to 0.05 mm.
While the specific gravity of the floating filter medium 2b is 0.035.
It is preferable to set it to 0.065. If the particle size is too large, the surface area of the carrier adhering in the packed bed becomes small, and if the particle size is too small, blocking tends to occur. Therefore, the above range is preferable in consideration of the balance between the two.

In the wastewater purifying apparatus of the present invention, the floating filter medium 2a in the denitrification section has a relatively large particle size, so that the filtration resistance of the entire packed bed is lower than that of the conventional wastewater purifying apparatus having a uniform particle diameter. Can be reduced. Further, ss in the drainage introduced from the raw water supply pipe 4 is mainly captured in the lower part of the packed bed. However, since the floating filter medium 2a of the denitrification part 6 has a relatively large particle diameter as described above, The ss amount that can be captured becomes larger than before. Therefore, clogging of the packed bed is less likely to occur, and the frequency of backwashing can be reduced as compared with a conventional wastewater purification device.

More specifically, when the ss load of the wastewater is made equal and the backwashing frequency is compared, the conventional method requires one backwash once every 28 hours, whereas the present invention requires one backwash. Then one backwash every 39 hours improved. For this reason, while the washing wastewater ratio to the treated water amount was conventionally 11.5%, the present invention has made it possible to reduce the washing wastewater amount ratio to 8.3%.

Backwashing is carried out by combining water washing for flowing down the treated water downward and air washing for blowing air from the washing air supply pipe 8 at the bottom of the tank. In this case, the floating filter media 2a and 2b are removed. It will be vigorously stirred while mixing as in the past. However, in the present invention, the floating medium 2a,
2b has a different specific gravity as well as a particle size, so after the backwashing, it is naturally separated due to a difference in specific gravity, and a floating filter medium 2a having a relatively large specific gravity is gathered at a lower portion of the packed bed, and a floating filter medium having a relatively small specific gravity. 2b will collect at the top of the packed bed.
As a result, the floating filter medium 2a to which the denitrifying bacteria have adhered returns to the denitrification section 6 again, and the floating filter medium 2b to which the nitrifying bacteria have adhered returns to the nitrifying section 7 again. In addition, a decrease in biological activity is prevented.

[0013]

As described above, the wastewater purifying apparatus using the floating filter medium of the present invention has a different particle size and specific gravity between the lower part and the upper part of the air diffuser than the conventional one. This also has the effect of reducing the frequency of backwashing and preventing a decrease in the biological activity of denitrifying bacteria and nitrifying bacteria accompanying backwashing.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing a conventional example.

[Explanation of symbols]

1 tank, 2 floating medium, 2a Denitrifying layer floating medium, 2b
Floating filter material for nitrification layer, 3 diffuser, 4 raw water supply pipe,
5 return pipe, 6 denitrification layer, 7 nitrification layer, 8 cleaning air supply pipe, 9 perforated plate

Continuing from the front page (71) Applicant 000005083 Hitachi Metals, Ltd. 1-2-1, Shibaura, Minato-ku, Tokyo (72) Inventor Yuzo Okamoto 2-56 Suda-cho, Mizuho-ku, Nagoya-shi, Aichi Nihon Insulators Co., Ltd. (72) Inventor Shigeki Takeda 2-56, Suda-cho, Mizuho-ku, Nagoya-shi, Aichi Japan Inside Nihon Insulators Co., Ltd. (72) Inventor Shoji Harada 3-1-1 Takasago, Urawa-shi, Saitama Saitama Prefecture Office (72) Inventor Yozo Uchino 3-15-1, Takasago, Urawa-shi, Saitama Saitama Prefecture Office (72) Inventor Kenichi Matsumoto 3-5-1 Takasago, Urawa-shi, Saitama Saitama Prefecture Office (72) Inventor Yu Kobayashi Saitama 3-1-1 Takasago, Urawa City, Saitama Prefecture Office (72) Inventor Yoichi Takano 3-1-1, Takasago, Urawa City, Saitama Prefecture Saitama Prefecture Office (72) Inventor Kiyohito Chikazawa Nishishinjuku 3-chome, Shinjuku-ku, Tokyo No. 4-7 Kurita Water Industries Ltd. (72) Inventor Yuji Yamada 5200 Mikajiri, Kumagaya-shi, Saitama F-term in Hitachi Metals, Ltd. (Reference) 4D003 AA05 AB08 BA04 BA06 DA22 EA01 EA19 EA28 EA30 4D040 BB57 BB63 BB82 DD03 DD14 DD31

Claims (2)

[Claims] 1. A wastewater purifying apparatus in which a granular floating filter material carrying a biofilm is filled in a tank, and the wastewater is passed upward from a lower part of the tank while being diffused by a diffuser means at a middle stage of the packed layer. In, the floating filter medium of the denitrification part lower than the diffuser means, the particle size is larger than the floating filter medium of the nitrification part upper than the diffuser means,
A wastewater purification device using a floating filter material, which has a large specific gravity. 2. The particle size of a floating filter medium in a denitrification part is 4.0 to 5.0 mm.
The particle size of the floating filter material in the nitrification section is 3.0 to 4.5 mm, the specific gravity of the former is 0.05 to 0.08, and the specific gravity of the latter is 0.035 to 0.065.
A wastewater purification device using the floating filter medium according to claim 1.