JP3024638B2 - Sewage treatment tank treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating a sewage purification tank using an aerobic filter bed method using a granular carrier for purifying merged wastewater discharged from general households and the like.

[0002]

2. Description of the Related Art A conventional treatment method using a sewage treatment tank is shown in FIG.
It will be described in detail based on. FIG. 4 is a cross-sectional view showing the structure of one of the conventionally used sewage purification tanks,
As shown in the figure, the sewage purification tank 1 includes partition walls A1, A2,
The anaerobic filter bed first chamber 2, the anaerobic filter tank second chamber 3, separated by A3 and A4, the contact aeration tank 4, the sedimentation tank 5, and the disinfection tank 6 were supplied from the inlet 9. The water 7 to be treated flows sequentially from the first chamber 2 of the anaerobic filter bed tank, is finally treated through the disinfecting tank 6, and is discharged from the outlet 10 as treated water 8.

The anaerobic filter tank first chamber 2, the anaerobic filter tank second chamber 3, and aerobic treatment for performing anaerobic treatment such as removal of coarse solids and depolymerization of organic matter by anaerobic microorganisms are performed. Each of the contact aeration tanks 4 to be filled is filled with contact materials C1, C2, and C3 for implanting microorganisms that decompose organic pollutants. Since it is desirable that the contact materials C1 to C3 have a large specific surface area (m ² / m ³ ), those having a shape such as a corrugated plate, a honeycomb, or a net ring are used.

[0004] In the contact aeration tank 4, biological sludge converted from organic pollutants or biofilm-separated sludge from the contact material C3 (hereinafter collectively referred to as SS) is generated.
S is separated by specific gravity in the sedimentation tank 5 in the latter stage by the sedimentation method.

As another conventional example, there is a treatment method using a sewage purification tank disclosed in Japanese Patent Application Laid-Open No. Sho 64-75095, which is an improvement of the conventional purification tank shown in FIG. This septic tank is
Explaining with reference to FIG. 4, the contact aeration tank 4 is a biofilm filtration tank for performing aerobic treatment filled with a granular carrier,
Further, the precipitation tank 5 is used as a treatment water tank, and the contact material C3 is also used as a filtration material.

In the biofilm filtration tank, the organic pollutants contained in the water to be treated 7 are converted into SS by microorganisms attached to the contact material C3, and are captured by the particulate carrier in C3. Thus, organic pollutants are aerobicly biodegraded in the biofilm filtration tank. The method of decomposing organic pollutants by the method just described is usually called a biological filtration method in the field of water treatment.

In the treatment method using the sewage purification tank using the biofilm filtration tank, the anaerobic filter bed tank is provided with a flow rate adjusting function in order to cope with fluctuations in the flow rate of the water 7 to be treated. The water to be treated 7 enters the first anaerobic filter tank 2 from the inlet 9,
After large garbage and contaminants are removed, the anaerobic filter bed tank 2
Enter Room 3. Here, the anaerobic filter bed first chamber 2 and the anaerobic filter tank second chamber 3 are provided with a communication port (not shown) at a depth of water at which the capacity corresponding to the flow rate fluctuation can be secured at the upper part of the filter bed. I have.

Next, the water 7 to be treated is transferred from the second chamber 3 of the anaerobic filter bed tank to the biofilm filtration tank by the metering pump 11, and is biodegraded in the biofilm filtration tank. The air diffuser 12 is provided for discharging air, and is provided for aerobic treatment. The treated water 7 treated in the biofilm filtration tank reaches the treated water tank, is further sterilized and treated in the disinfecting tank 6, and is discharged from the outlet 10 as treated water 8.

[0009] If the operation is continued in this state, in the biofilm filtration tank, the accumulated SS and the biofilm adhered to the contact material C3 increase the filtration resistance, and a predetermined amount of filtered water cannot be obtained. The contact material C3 is periodically backwashed. In the backwash method, the treated water in the treated water tank is jetted to the bottom of the biofilm filtration tank by the backwash pump 13, the backwash water is taken out from the upper part of the tank, and returned to the first anaerobic filter tank 1 chamber 2 (not shown). Is what you do.

[0010]

However, the above-mentioned conventional method for treating a sewage treatment tank has the following problems. (1) In the sedimentation tank 5 of the sewage purification tank 1, the water 7
And the effect of seasonal changes in water temperature cannot be accommodated, and the quality of the treated water 8 is unstable. (2) In the sewage treatment tank 1 disclosed in Japanese Patent Application Laid-Open No. 64-75095, the biofilm filtration tank is filled with a granular ceramic contact material C3 of about 5 mm in order to have a biological decomposition function and a physical filtration function. However, because of this, clogging is likely to occur, and the time during which filtration can be continued is short. (3) A backwashing operation is performed to eliminate the clogging, but a submersible pump having a large power is required to satisfactorily backwash the entire filtration tank. In view of the above problems, the present invention provides a method for treating a sewage purification tank capable of continuously and stably obtaining good treated water, reducing required power and reducing the size of the apparatus. The purpose is.

[0011]

According to the present invention, there is provided a sewage purifying tank, in which a plurality of treatment tanks are formed by partitioning the inside of the tank with a partition wall, and water to be treated is sequentially transferred to the treatment tanks for purification. anaerobic treatment tank first chamber having a filter bed from the side, the anaerobic treatment tank second chamber having a filter bed, aerobic treatment tank having a filter bed layers, the process water tank, are arranged in the order of disinfecting bath, the anaerobic treatment tank first In the aerobic treatment tank, the filter bed layer is divided into upper and lower filter bed layers filled with granular carriers, and air is diffused below each of the upper and lower filter bed layers. A member is installed to aerobically treat the advection water from the anaerobic treatment tank second chamber, the treated water from the aerobic treatment tank is stored in the treated water tank, and the treated water from the treated water tank is disinfected in the disinfection tank. When disinfecting and discharging the effluent from the sewage treatment tank, and washing the aerobic treatment tank, The detergent drain by transfer pump from the side, characterized in that to transfer to the anaerobic treatment tank first chamber.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a sewage purification tank comprising at least five tanks, in which anaerobic treatment of water to be treated is performed in first and second tanks, and then in a third tank. Aerobic treatment is performed, and the treated water treated in the third tank is stored in the fourth tank, and the treated water is finally disinfected in the fifth tank and discharged out of the sewage purification tank. In the third tank washing step, washing drainage is transferred to the first tank by a transfer pump from below the filter bed below the third tank.

First, a method of treating wastewater by an aerobic filter bed tank, which is a third tank using granular material as a packed bed, will be described with reference to FIG. In FIG. 1, (a) is a diagram showing a normal processing state of an aerobic filter bed tank, and (b) is a view showing a cleaning state of an aerobic filter tank processing tank.

1 (a), the aerobic filter bed tank 41 is filled with a particulate carrier 14 as an aerobic filter bed layer. It is divided into two sections, an upper section R zone and a lower section F zone are formed, and the granular carrier 1 is formed above and below the upper section R zone and the lower section F zone.
Porous members 15 and 17 which do not pass through 4 are provided horizontally across, and a porous member 16 which divides the upper section R zone and the lower section F zone is provided. Further, the diffusing member 1 is provided below the granular carrier 14 in the upper zone R zone and the lower zone F zone.
8 and 19, and the porous member 17 below the lower section F zone.
Transfer pump 2 from the lower part of the tank to the first chamber of the anaerobic filter tank
Cleaning drainage drain pipe 21 which is withdrawn as cleaning drainage through 0
Is provided. An opening 23 communicates the lower part of the aerobic filter bed tank 41 with the treated water tank 22. At this time, the upper section R
The diffuser 18 below the zone may be provided either above or below the porous member 16 (18 '). Although an air lift pump is used in the drawings for the transfer pump 20 for transferring the washing wastewater, a normal submersible pump using power may be used. Further, it is desirable that the opening 23 communicating the lower part of the aerobic filter bed tank 41 and the treatment water tank 22 has a diameter smaller than the diameter of the washing drainage pipe 21. Further, as shown in FIG. 2A, the opening 23 is provided so as to be separated from the washing / drainage discharge pipe 21, and the opening 23 'may have a reduced pipe diameter, as shown in FIG. 2B. A check valve 24 for preventing backflow from the treated water tank 22 may be provided.

The wastewater treatment having the above-described structure is performed as described below. The to-be-processed water 25 which came out of the anaerobic filter bed tank 2 enters the upper section R zone of the aerobic filter bed tank 41. R
The particulate carrier 14 in the zone is filled to the extent that it flows in the porous members 15 and 16 due to air bubbles from the diffusing member 18. The diffusing member 18 has a function of dissolving oxygen to diffuse R.
It is desirable to be installed so as to be spread throughout the zone. The to-be-treated water 25 entering the R zone is treated by the aerobic microorganisms inhabiting the granular carrier 14, and the decomposition of BOD and the nitrification of ammonia progress. In the R zone, the capture of SS is not sufficient because the granular carrier 14 is flowing,
The passing water containing SS descends in the R zone and enters the lower zone F zone. The granular carrier 14 in the F zone is filled to such an extent that it flows by air bubbles diffused from the diffusing member 19 only at the time of cleaning described later.

The passing water that has reached the F zone is the granular carrier 14
Is statically formed as a filtration layer, so that SS contained in the passing water is captured and removed by the filtration layer. Also,
In the F zone, dissolved oxygen is also brought in from the R zone, where aerobic microorganisms adhere and inhabit, and the remaining BOD that could not be completely decomposed in the R zone is decomposed and nitrification of the residual ammonia is performed.

As described above, the water 25 to be treated is mainly decomposed of BOD and nitrified by ammonia in the upper zone R zone,
SS is removed in the lower section F zone. After passing through the F zone, the water reaches the treated water tank 22 from the opening 23 and is discharged as treated water 26 from above. Aerobic filter bed tank 41
When the process is continued, the trapped SS gradually closes the gap between the granular carriers 14. This tendency is remarkable in the lower zone F zone which captures a lot of SS as described above. Therefore, it is necessary to wash the aerobic filter bed tank 41.

Next, a method of cleaning the aerobic filter bed tank 41 is shown in FIG.
Explaining using (b), when shifting from normal processing to cleaning, air diffusion is started from the air diffusion member 19 below the porous member 17 in the lower section F zone. Due to the air bubbles generated by the aeration, the particulate carrier 14 in the F zone starts to flow, and the SS trapped between the carriers is released. At this time, the transfer pump 20 connected to the washing drainage pipe 21 is operated, and water in the tank containing SS is drawn out as washing wastewater 27 into the first chamber of the anaerobic filter bed tank. Due to the return of the washing drainage, the water in the tank of the first anaerobic filter tank is sequentially pushed out, and is passed through the second chamber of the anaerobic filter tank to the upper part of the aerobic filter tank 41, where the water 2
Enter 5 That is, the treated water in the second chamber of the anaerobic filter tank is supplied as washing water.

The completion of the cleaning is completed by stopping the air diffusion from the air diffusing member 19 and stopping the transfer pump 20 to return to a normal processing state. By performing the above cleaning, the F zone can be bubbled with an extremely small amount of air, and the water in the tank in the F zone is drawn out.
SS can be washed out with a small amount of washing water, and the required power is small. Further, the treatment water tank 22 for securing the cleaning water is substantially unnecessary and small, and the capacity of the entire tank can be reduced.

Regarding the granular carrier 14 to be filled in the aerobic filter bed tank 41, the characteristics required for the carrier are that the amount of microorganisms adhered (retained amount) is large, that the carrier can be easily washed, physicochemically and mechanically. Must be durable. Aerobic filter bed tank 41
In order to improve the treatment efficiency, it is preferable that the amount of microorganisms attached to the carrier (retention amount) is large. For this purpose, voids such as particles or fibers having pores therein and communicating with the pores are formed. A fiber mass is desirable. Examples of such inorganic carriers include perlite, shirasu balloon, foamed concrete, activated carbon, porous ceramic, porous glass, and the like. Synthetic resin-based carriers include foamed molded products such as polyethylene, polypropylene, polyvinyl chloride, polyurethane, and acetalized polyvinyl alcohol, fiber bundles with irregularly entangled fibers, non-woven fabrics with irregularly laminated fibers, and fibers bound together. Fiber lump and the like.

However, in the washing of the aerobic filter bed tank, it is necessary that excessive microorganisms and SS trapped between the carriers are easily separated from the carriers by bubbling and water flow. This depends on the specific gravity of the carrier, and it is not preferable that the specific gravity is too large or too small. Specific gravity suitable for use as a carrier is generally about 0.9 to 1.1.

In view of the specific gravity, many inorganic carriers are too many, and many synthetic resin carriers are suitable. In particular, polyvinyl chloride, polyurethane, acetalized polyvinyl alcohol, and various fibers such as polyester and nylon among the above-mentioned fibers have an appropriate specific gravity. Polyethylene has a small specific gravity in that respect.
However, the specific gravity of polyethylene (communicating foam) increases when microorganisms adhere thereto, and the polyethylene (appropriate specific gravity) becomes about 1.005. Therefore, as the polyethylene communicating foam, microorganisms to which microorganisms are attached in advance can also be used. Alternatively, a material having another specific gravity adjusted can be used. Specifically, the one obtained by impregnating and drying the interconnected foam with the emulsion paint,
Examples include foams obtained by adding calcium carbonate, barium sulfate, and other specific gravity adjusters during foam molding, and foams obtained by adding a hydrophilic substance such as a polyethylene glycol ester or a glycerin fatty acid ester during foam molding.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG.
The sewage purification tank 28 is partitioned by partition walls 29, 30, 31, and 32. The first anaerobic filter bed tank 33 for performing anaerobic treatment in the first tank contains a contact material 34 and removes coarse solids. And anaerobic microorganisms reduce the molecular weight of organic substances. Anaerobic filter bed tank 2 to perform anaerobic treatment in the second tank
A contact material 36 is also stored in the chamber 35 to promote further decomposition of organic substances. The aerobic filter bed tank 41 for performing the aerobic treatment in the third tank has the configuration described in FIG. 1, and stores the above-described granular carrier 14. The function is divided into a zone and a lower section F zone. The main operation in each zone has been described above and will not be described here. Air is always inserted into the air diffusing member 18 even in a normal processing state and during cleaning, and air is inserted into the air diffusing member 19 only during cleaning. The fourth treatment tank 22 is in communication with the aerobic filter bed tank 41 via the opening 23. The treated water tank 22 is provided with a cleaning drainage discharge pipe 2.
1 and the transfer pump 20 and for transferring the treated water to the disinfection tank 37 of the fifth tank.

In the sewage purification tank 28 described above, B
In addition to the removal of OD and SS, in the case of further removing nitrogen, the transfer pump for circulation 38 can be installed in the treated water tank 22 and a part of the treated water can be returned to the first anaerobic filter bed tank. .

The processing steps and functions of the sewage purification tank 28 according to a normal processing method will be described.
It is supplied from the inlet and enters the first chamber 33 of the anaerobic filter tank, where coarse solids are removed by the contact material 34 and, at the same time, organic substances are decomposed by anaerobic and facultative anaerobic microorganisms. Transfer pump 3 for circulation
If it is returned via 8, the denitrification is also performed here. Next, the advection water that passed through the first anaerobic filter tank 33 is
It reaches the upper part of the anaerobic filter bed second chamber 35 and enters the tank 35. Here, further decomposition and denitrification of organic substances are performed. The advection water 25 that has passed through the anaerobic filter tank second chamber 35 is supplied to the aerobic filter tank 41.
And an aerobic biodegradation is performed in the tank 41. That is, in the aerobic filter bed tank 41, decomposition of organic substances and nitrification of ammonia by the aerobic microorganisms attached to the granular carrier 14 are performed by the air supplied from the diffusing member 18 in the upper zone R zone. Subsequently, in the lower zone F zone, the particulate carrier layer is in a stopped state, so that SS is captured. At the same time, an aerobic atmosphere is maintained by dissolved oxygen carried over from the R zone, and aerobic biodegradation is also performed. By this step, the water 39 to be treated is removed from the organic matter and SS, and if necessary, nitrogen, so that the treated water 39 becomes highly treated water with good transparency.
After being sterilized in step 7, it is discharged as discharge water 40 out of the system.

Here, when there is a large fluctuation in the flow rate of the water 39 to be treated, the opening 23 connecting the aerobic filter bed tank 41 and the treated water tank 22 is provided with an appropriate resistance to the passage of the advancing water so that each tank 39 Can be provided with a function of preventing abrupt advection, that is, adjusting the flow rate.

Next, the washing step will be described. The washing instruction is started when the water level in the aerobic filter bed tank 41 rises to a predetermined water level or when a predetermined time elapses by setting a timer. In the case of setting the timer, it is preferable to set it at midnight when the inflow of the water 39 to be treated is small.

In the cleaning step, air is diffused from the air diffusing member 19 and the transfer pump 20
Is operated to pull out the SS separated by bubbling from the washing / drainage discharge pipe 21 together with the water in the tank, and transfer the SS from the washing / drainage transfer pipe 42 to the first chamber 33 of the anaerobic filter bed tank. Due to the return of the washing drainage, the water in the anaerobic filter tank first chamber 33 and the anaerobic filter tank second chamber 35 is sequentially pushed out, and the treated water in the anaerobic filter tank second chamber 35 is removed from the aerobic filter tank. 41. In other words, by extracting the washing wastewater in the F zone of the aerobic filter bed tank 41 from below, washing water is supplied from the R zone to perform washing.

Here, since the water level in each tank is almost the same during washing, even if the transfer pump 20 is operated during washing, there is little backflow from the treated water tank 22 through the opening 23, and the F zone It is possible to efficiently extract the washing wastewater. To increase the effect, the opening 2
It is preferable to provide a check valve 24 in 3.

On the other hand, even if this washing operation is performed, the granular carrier 14 in the R zone and the F zone cannot be moved back and forth by the porous member 16 that separates both, so that the carrier amount in each zone does not change. The end of the cleaning is completed by stopping the air diffusion from the air diffusing member 19 and stopping the transfer pump 20.

[0031]

As described above, according to the method for treating a sewage treatment tank according to the present invention, it is possible to efficiently remove BOD and SS, and nitrification of ammonia is carried out, so that a highly transparent treatment can be performed. Water can be obtained stably. Further, when the aerobic filter bed tank is filled with a granular carrier having a specific gravity close to 1, the power required for washing can be significantly reduced. Further, the size of the sewage purification tank can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an aerobic filter bed tank showing an embodiment of the present invention, wherein (a) shows a normal processing state and (b) shows a washing state.

FIG. 2 is an enlarged view of an opening for communicating an aerobic filter bed tank and a treatment water tank according to an embodiment of the present invention.

FIG. 3 is a sewage purification tank showing an embodiment of the present invention,
(A) is a schematic plan view, and (b) is an AA sectional view of (a).

FIG. 4 is a schematic sectional view of a conventional sewage purification tank.

[Explanation of symbols]

1. Sewage septic tank 2. 2. Anaerobic filter bed tank 1st room Anaerobic filter bed tank second room 4. Contact aeration tank 5. Settling tank 6. Disinfection tank 7. 7. Water to be treated Treated water 9. Inlet 10. Outlet 11. Metering pump 12. 12. Aeration pipe for aeration
Backwash pump 14. Granular carrier 15. Porous member 16.
Porous member 17. Porous member 18. Air diffuser 19. Diffuser member 20. Transfer pump 21. Wash drainage pipe 2
2. Treated water tank 23. Opening 24. Check valve 25. Water to be treated 26. Treated water 27. Wash drainage 28. Sewage septic tank 29. Partition wall 30. Partition wall 31. Partition wall 3
2. Partition wall 33. Anaerobic filter tank 1st room 34. Contact material
35. Anaerobic filter tank 2nd room 36. Contact material 37. Disinfection tank 38. Transfer pump for circulation 39. Water to be treated 40. Discharge water 41. Aerobic filter bed tank 42. Cleaning drainage transfer pipe

Continuation of the front page (72) Inventor Yuji Koizumi 1250 Shimoe-ren, Shimodate-shi, Ibaraki Pref. Hitachi Chemical Co., Ltd. Yuki factory (56) References JP-A-64-75095 (JP, A) JP-A-6-106181 (JP, A) JP-A-6-285484 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C02F 3/00-3/34

Claims (1)

(57) [Claims] An anaerobic treatment having a sewage purification tank for purifying by purifying by successively advancing the water to be treated into said treatment tank by partitioning the inside of the tank with a partition wall. The first anaerobic treatment tank, the second anaerobic treatment tank having a filter bed, the aerobic treatment tank having a filter bed layer, the treatment water tank, and the disinfecting tank are arranged in this order. The first anaerobic treatment tank and the second anaerobic treatment tank In the aerobic treatment tank, the filter bed layer is divided into upper and lower filter bed layers filled with granular carriers, and a diffuser member is installed below each of the upper and lower filter bed layers to form an anaerobic treatment tank. The advection water from the second chamber is subjected to aerobic treatment, the treated water from the aerobic treatment tank is stored in the treated water tank, and the treated water from the treated water tank is disinfected in the disinfecting tank and discharged outside the sewage purification tank. When washing the aerobic treatment tank, the transfer pump is used from below the lower filter bed layer of the aerobic treatment tank. Method of processing septic tank, characterized in that for transferring the cleaned wastewater into the anaerobic treatment tank first chamber.