JP2002166287A - Device and method for waste water treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently solid-liquid separate and treat a biologically reacted solution which is biologically treated in a reaction tank. SOLUTION: A separation tank 19, in which at least one vertical type filtration body 9 comprising a material formed by vertically combining hollow and flat plates 9A provided with a filter cloth in a multistage state is dipped for setting, is provided on the side of the outlet of a biological reaction tank 6, the biologically reacted solution 15 from the biological reaction tank 6 is solid- liquid separated by the filtration body 9 making use of the water head difference in the separation tank 19, and then the treated water 13 after the separation is exhausted to the outside of the filtration body 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method and an apparatus for treating wastewater, and more particularly to a method and an apparatus for efficiently performing solid-liquid separation on a biological reaction solution which has been biologically treated in a reaction tank when biologically treating sewage. A possible wastewater treatment method and apparatus.

[0002]

2. Description of the Related Art Conventional treatment methods in sewage treatment plants
This will be described with reference to the drawings.

FIG. 2 is a schematic configuration diagram showing a conventional waste liquid treatment apparatus in a sewage treatment plant.

As shown in FIG. 2, inflow sewage 1 is first solid-liquid separated in a sedimentation basin 2 by gravity sedimentation treatment. The settled solids are collected by the sludge scraper 3 and sent to the concentration step as sludge 4 from the settling basin. On the other hand, the first settling pond overflow water 5 which is the supernatant water after the sedimentation treatment is supplied to the reaction tank 6. An air diffuser 7 is installed in the reaction tank 6, and is exploded by air supplied from a blower 8 to perform an activated sludge treatment by a biological reaction.

[0005] The biological reaction solution 15 thus treated with the activated sludge is supplied to a final sedimentation basin 16 where it is again subjected to
Solid-liquid separation is performed by gravity sedimentation. The supernatant water thus obtained in the final settling basin 16 is supplied to the sand filtration facility 17. Then, after the turbid matter is further removed, the turbid matter is supplied to a sterilization facility 18 where it is sterilized. And
The sewage treated water 13 sterilized in this way is used for rivers,
Released into lakes or waters or reused. The sludge 12 drawn from the final settling basin 16 is returned to the reaction tank 6.

On the other hand, in advanced treatment methods, such as nitrogen and phosphorus removal, which are being actively employed to prevent eutrophication of public water bodies, a reaction tank is required to increase the reaction rate. In many cases, the system is operated at a higher solid matter concentration than in the case of the standard activated sludge method. Therefore, it is necessary to subject the high-concentration sludge mixture flowing out of the reaction tank to a solid-liquid separation treatment.

[0007] In particular, in large cities, many final sedimentation basins compatible with the standard activated sludge method are already in operation.
In order to adopt the advanced treatment, it is strongly desired to develop a new waste liquid treatment means which can replace the final settling basin 16 of FIG. 2 or complement it.

[0008]

As described above, in a biological treatment apparatus for activated sludge or the like which decomposes organic matter in water by a biological reaction, generally, the biological sludge is separated into solid and liquid by a sedimentation separation means. A sedimentation basin is provided. However, the conventional biological treatment apparatus provided with a sedimentation pond at the latter stage of the biological reaction tank has the following problems.

In the sedimentation treatment for sedimentation and separation of sludge due to a difference in specific gravity, there is a limit in sludge separation performance, and the quality of treated water deteriorates when the inflow load changes or when bulking occurs.
For this reason, when a high treatment water quality is required, equipment such as a rapid filter and a strainer is required at the subsequent stage of the sedimentation basin.

[0010] In many cases, troubles such as generation of scum and floating of sludge occur in the final sedimentation basin, and water quality often deteriorates.

[0011] The settling basin requires a large installation space.

On the other hand, a method has been proposed in which biological sludge is separated by a membrane using an ultrafiltration membrane or a microfiltration membrane instead of the sedimentation separation. According to this membrane separation treatment, it is possible to obtain treated water from which suspended matter is highly removed without requiring a large space such as a sedimentation pond.

[0013] However, in the membrane separation treatment using an ultrafiltration membrane or a microfiltration membrane, the operating energy is large, the membrane is contaminated by the substance treated with the membrane, and the filtration performance is reduced due to blockage of the membrane pores. There is a drawback that a proper chemical cleaning is essential.

[0014] Accordingly, an object of the present invention is to provide a wastewater treatment method and apparatus capable of solving the above-mentioned problems in the conventional biological treatment and enabling stable and efficient solid-liquid separation treatment.

[0015]

According to the first aspect of the present invention,
A separation tank in which at least one vertical filter body formed by combining a plurality of hollow flat plates provided with a filter cloth in upper and lower stages is immersed and arranged, provided on the outlet side of the biological reaction tank, and the separation tank is provided in the separation tank. It is characterized in that the biological reaction solution from the biological reaction tank is separated into solid and liquid by utilizing the head difference by the filter, and the separated treated water is discharged from the filter.

A second aspect of the present invention is characterized in that solid-liquid separation is performed while peeling and removing solid matter adhered to the surface of the filter cloth.

The invention according to claim 3 is characterized in that a fluid is sprayed on the surface of the filter cloth or a fluid is pressed into the inside of the hollow flat plate in order to peel and remove the solid matter. is there.

The invention according to claim 4 is characterized in that a scraper is used to peel off and remove the solid matter.

The invention according to claim 5 is characterized in that the treated water is treated using sand filtering means.

According to a sixth aspect of the present invention, there is provided a biological reaction tank, a separation tank provided on an outlet side of the biological reaction tank, and at least one vertical filter body immersed and disposed in the separation tank. The filter is characterized in that the filter is composed of a plurality of hollow flat plates provided with filter cloths combined in upper and lower stages.

[0021] The invention according to claim 7 is characterized in that a means for removing solid matter attached to the surface of the filter cloth is provided.

[0022] The invention according to claim 8 is characterized in that a sand filtration facility for further treating the treated water from the filter is provided.

[0023]

Next, an embodiment of a wastewater treatment apparatus according to the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing a wastewater treatment apparatus according to the present invention.

As shown in FIG. 1, inflow sewage 1 is first separated into solid and liquid by gravity sedimentation in a sedimentation basin 2. The settled solids are scraped by the sludge scraper 3 and first discharged from the settling basin 2 as the settling basin drawn sludge 4. On the other hand, the first sedimentation pond
Is supplied to a reaction tank 6, where air supplied by a blower 8 is supplied from an air diffuser 7 to be aerated, and a biological reaction is performed.

The biological reaction solution 15 thus obtained is
Is supplied to a separation tank 19, where it is subjected to a solid-liquid separation treatment. In the separation tank 19, a vertical filter body 9 formed by combining a plurality of hollow flat plates 9A provided with filter cloths in upper and lower stages is immersed. The biological reaction liquid 15 supplied into the separation tank 19 is filtered by the filter cloth of each hollow flat plate 9A of the vertical filter body 9 to be separated into solid and liquid. The filtration is driven by a head difference which is a difference between the liquid level in the separation tank 19 and the treated water level in the solid-liquid separation means 9. The change of the head difference can be adjusted by changing the withdrawal amount of the pump 14 for withdrawing the treated water 13 in the filter body 9,
Usually, it is preferable to be within the range of 0.1 m to 3 m.

Openings are provided on the upper and lower surfaces of each hollow flat plate 9A of the vertical filter body 9, and these openings are covered with a filter cloth. The shape of the opening is not particularly limited, but is preferably a shape that does not allow the attached filter cloth to bend due to the head pressure. When the hollow flat plate 9A has a disk shape, the diameter of the disk diameter is not particularly limited. However, if the diameter is too large, it becomes difficult to remove solid substances attached to the surface of the filter cloth. Is preferred. The length of the filter body 9 in the vertical direction is not particularly limited as long as the filter body 9 can be immersed and installed in the separation tank 19, but is suitably in a range of about 500 mm to 4000 mm. The material of the hollow flat plate 9A is not particularly limited, and a metal such as stainless steel or a resin such as FRP can be used.

As the filtration proceeds, solids adhere to the surface of the filter cloth of the filter body 9 and the filtration speed decreases. For this reason,
The solids adhering to the filter cloth surface of the filter body 9 are continuously or intermittently peeled off by the solids peeling means 10.
The solid material peeling means 10 has a structure in which water is sprayed on the filter cloth to remove the solid matter attached to the filter cloth. The filter cloth is vibrated by means of a structure for removing adhered solid matter, a washing means by air, a structure for scraping solid matter adhered to the filter cloth by a scraper, a scraper by a scraper and mechanically or ultrasonically, Although a cleaning means by vibration or the like having a structure for removing solid matter attached to the filter cloth can be used, a scraping means using a scraper is most preferable because the driving power required for the peeling means is small.

In this case, as the scraper shape, any of a linear shape and a spiral shape can be used. The material of the scraper is not particularly limited, and stainless steel, synthetic resin, or the like can be used. However, the scraper has high resistance to abrasion, the sludge that is not easily adhered to the scraper, and the light weight. In view of this, ultrahigh molecular weight polyethylene is particularly effective.

A fluid such as water or air is applied to the hollow flat plate 9.
It is also possible to press-fit into A and backwash the solid matter attached to the filter cloth.

The solid material peeling means 10 peels and removes solid matter adhering to the filter cloth surface of the filter body 9 while rotating the filter cloth surface of the vertical filter body 9 at an arbitrary rotation speed by the drive motor 11. The solid material peeling means 10 may be fixed, and the solid matter adhering to the filter cloth surface may be peeled and removed while the filter body 9 is rotated by the drive motor 11.

The treated water in each hollow flat plate 9A of the vertical filter 9 is drawn by a treated water drawing pump 14.

Although not shown, if the treated water 13 is treated using the sand filtration equipment shown in FIG. 1, clearer treated water can be obtained.

The concentrated biological reaction solution in the separation tank 19 is continuously or intermittently withdrawn from the separation tank 19 as the separation tank withdrawal sludge 12, and a part thereof is supplied into the reaction tank 6 as return sludge.

[0035]

As described above, according to the present invention, a separation tank in which at least one vertical filter body formed by combining a plurality of hollow flat plates provided with filter cloths in upper and lower stages is immersed. Is provided on the outlet side of the biological reaction tank, and a solid-liquid separation of the biological reaction liquid from the biological reaction tank is performed by utilizing the head difference by the filter in the separation tank. Separation can be performed stably and reliably with low power without using a sedimentation tank that requires a large installation space or membrane separation means that requires a large amount of operating power and chemical cleaning of the membrane. The present invention can be applied to an increase in the MLSS of a reaction tank corresponding to the treatment, and further to a biological treatment such as a high-concentration activated sludge method, and the effect is extremely large.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a wastewater treatment device of the present invention.

FIG. 2 is a schematic configuration diagram showing a conventional waste liquid treatment device in a sewage treatment plant.

[Explanation of symbols]

 1: Sewage 2: First settling basin 3: Sludge scraper 4: Sludge withdrawn from first settling basin 5: First settling basin overflow 6: Reaction tank 7: Air diffuser 8: Blower 9: Vertical filter 9A: Hollow flat plate 10: Solid substance peeling means 11: Drive motor 12: Separation tank drawing sludge 13: Treated water 14: Pump 15: Biological reaction liquid 16: Final sedimentation basin 17: Sand filtration equipment 18: Sterilization equipment 19: Separation tank

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) B01D 36/04 B01D 29/04 520A 520B 520D 530A 29/08 520A 540A 29/38 510A 530A 530Z 550B (72) Inventor Shohei Fukada 1-2-1 Marunouchi, Chiyoda-ku, Tokyo F-term (reference) 4D028 BC17 BD17 4D066 AA05 AA07 AB06

Claims (8)

[Claims] 1. A separation tank in which at least one vertical filter body formed by combining a plurality of hollow flat plates provided with a filter cloth in upper and lower multistages is provided on the outlet side of a biological reaction tank, A wastewater treatment method comprising: separating a biological reaction solution from the biological reaction tank from the biological reaction tank by solid-liquid separation by utilizing a head difference by the filter in the separation tank; and discharging treated water after separation from the filter. . 2. The wastewater treatment method according to claim 1, wherein solid-liquid separation is performed while removing solid substances adhered to the surface of the filter cloth. 3. The wastewater treatment according to claim 2, wherein a fluid is sprayed on the surface of the filter cloth or a fluid is pressed into the hollow flat plate to remove the solid matter. Method. 4. The wastewater treatment method according to claim 2, wherein a scraper is used to peel and remove said solid matter. 5. The wastewater treatment method according to claim 1, wherein the treated water is treated using a sand filtration facility. 6. A biological reaction tank, comprising: a separation tank provided on an outlet side of the biological reaction tank; and at least one vertical filter immersed and disposed in the separation tank. A wastewater treatment apparatus comprising a plurality of hollow flat plates provided with filter cloths combined in upper and lower stages. 7. The wastewater treatment apparatus according to claim 6, further comprising means for removing solid matter attached to the surface of the filter cloth. 8. The wastewater treatment apparatus according to claim 6, further comprising a sand filtration facility for further treating the treated water from the filter.