JP2697561B2 - Sewage septic tank - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sewage treatment tank incorporating a biological filtration method using a granular carrier for purifying combined wastewater discharged from homes and the like.

[0002]

2. Description of the Related Art A conventional sewage treatment tank will be described in detail with reference to FIG.

FIG. 4 is a cross-sectional view showing the structure of a well-known conventional sewage purification tank 1. As shown in the figure, the sewage purification tank 1 is composed of a first anaerobic filter bed tank partitioned by partition walls A1 to A4. 2. Anaerobic filter bed second chamber 3, contact aeration tank 4, sedimentation tank 5, and disinfecting tank 6, and water to be treated 7 supplied from inflow port 9 is supplied from anaerobic filter tank first chamber 2 The water flows sequentially, and finally passes through the disinfection tank 6 and is discharged as treated water 8 from the outlet 10.

[0004] Each of the first and second anaerobic filter tanks 2 and 3 and the contact aeration tank 4 are filled with contact materials C1 to C3 for implanting microorganisms that decompose organic pollutants. . Since these contact materials C1... C3 desirably have a large specific surface area (m ² / m ³ ), corrugated, honeycomb, or net-like materials are used.

[0005] In the contact aeration tank 4, biological sludge (hereinafter referred to as SS) converted from organic pollutants or exfoliated sludge due to biofilm exfoliation from the contact material C 3 is generated. In the tank 5, specific gravity is separated by a precipitation method.

Another conventional example is disclosed in Japanese Patent Laid-Open Publication No. Sho 64-75095, which is an improvement of the above-mentioned well-known conventional waste water purifying tank.
The configuration of the sewage purification tank disclosed in Japanese Patent Publication No. 95 is almost the same as that of the above-described conventional example, and thus will be described in detail with reference to FIG.

In the figure, a sewage purification tank 1 disclosed in Japanese Patent Application Laid-Open No. 64-75095 has a contact aeration tank 4 in the above-mentioned conventional example as a biological filtration tank and a sedimentation tank 5 as a treated water tank. The contact material C3 also functions as a filtering material.

[0008] In the biological filtration tank 4, the organic pollutants contained in the water 7 to be treated are converted into SS by microorganisms attached to the contact material C 3, and the SS is filtered by the contact material C 3 by a sieving filtration method. Filtered and captured.

The organic pollutant is aerobicly biodegraded in the biological filtration tank 4 by the combined use of the microorganism biofilm attached to the contact material C3 and the SS captured by the contact material C3.

[0010] The above-mentioned method for decomposing organic pollutants is generally called a biological filtration method in the field of water treatment.

Further, in order to cope with the fluctuation of the flow rate of the water 7 to be treated, the anaerobic filter tank is provided with a flow rate adjusting function.

In the sewage treatment tank 1, the water 7 to be treated enters the first anaerobic filter bed tank 2 through the inlet 9, and after large trash and small foreign matters are removed, the sewage 7 enters the second anaerobic filter tank 2. enter.

Here, the first and second chambers 2 and 3 of the anaerobic filter tank are opened at the upper part of the water depth so as to have a volume corresponding to the flow rate fluctuation (not shown).

Next, the water 7 to be treated enters the biological filtration tank 4 from the second chamber 3 of the anaerobic filter bed by means of the quantitative supply pump 11, and is subjected to aerobic treatment in the biological filtration tank 4, so that air is discharged. From the aeration diffuser 12.

Thus, the organic pollutants are aerobically biologically decomposed by the SS captured in the biological filtration tank 4 and the biological film attached to the contact material C3.

The treated water 7 from which the organic pollutants have been decomposed and SS has been removed in the biological filtration tank 4 reaches the treated water tank 5, is further sterilized in the disinfecting tank 6, and is discharged from the outlet 10 as treated water 8. Is done.

If the operation is continued in such a state, in the biological filtration tank 4, the filtration resistance increases due to the accumulation of the captured SS and the biological film attached to the contact material C3, and a predetermined amount of filtered water cannot be obtained. Backwashing of the contact material C3 is periodically performed.

In the backwashing method, the treated water in the treated water tank 5 is jetted to the bottom of the biological filtration tank 4 by the backwash pump 13 and the backwash water is taken out from the upper part and returned to the first anaerobic filter bed tank 2. (Not shown).

[0019]

However, the above-mentioned conventional sewage treatment tank has the following problems. (1) The sedimentation tank 5 in the well-known conventional wastewater purification tank 1
Then, due to the fluctuation of the flow rate of the water to be treated 7 or the effect of seasonal water temperature change, it is not possible to cope with this fluctuation only by the specific gravity separation by the precipitation method, and the treated water 8 contains a large amount of SS. It becomes cloudy. (2) In the sewage treatment tank 1 disclosed in JP-A-64-75095, which is an improvement of the above-mentioned conventional example, since the biological filtration tank 4 has a physical filtration function and a biological decomposition function, it is 10 m in length.
It is necessary to fill the contact material C3 having a small particle size of about m or less, so that clogging is likely to occur, and the time during which filtration can be continued is short. (3) In addition, since the biological filtration tank 4 fulfills the above two functions, the tank volume becomes large, so that it is difficult to perform backwashing over the entire tank, and the filtering action is reduced. (4) Further, the amount of backwash water is generally required to be equal to or greater than that of the biological filtration tank 4, so that the larger the tank, the larger the amount of backwash water.

Accordingly, the present invention has been made in view of the above problems, and has as its object to provide a small-sized sewage purification tank capable of continuously and stably obtaining good treated water and reducing the amount of washing water. .

[0021]

In order to achieve the above object, according to the present invention, a plurality of treatment tanks are formed by partitioning the inside of a tank with a partition wall, and water to be treated is sequentially transferred to these treatment tanks for purification. In the sewage purification tank, the plurality of treatment tanks are arranged in the order of the first anaerobic filter tank, the second chamber, the biological filtration tank, the treatment water tank, and the disinfection tank, and the flow rate is adjusted above the first anaerobic filter tank. A volume part having a function is provided, and the liquid passing through the first chamber of the anaerobic filter tank is transferred to the upper part of the second anaerobic filter tank and allowed to flow down, and the liquid naturally flows from the bottom of the second chamber to the upper part of the biological filter tank at the subsequent step. The biological filtration tank is provided with a filter bed containing granules, and the biological filtration layer is separated into two upper and lower compartments at intervals to form an upper compartment and a lower compartment. Provide porous members horizontally and horizontally at the top and bottom, and below the porous members at the bottom of the upper section and lower section The effluent in the tank is withdrawn from the washing drainage pipe between the porous members partitioning the upper and lower compartments as washing wastewater into the first chamber of the anaerobic filter bed tank, and the biological filtration tank is flowed downward. The flow-through liquid that has flowed down is transferred from the bottom of the biological filtration tank to the treatment water tank, is discharged from the upper part of the treatment water tank to the disinfection tank, and is discharged outside the system. It is returned to one room.

First, a method of treating wastewater by a biological filtration method using granular materials as a carrier bed will be described with reference to FIG.
In FIG. 1, (a) is a diagram showing a normal treatment state of the biological filtration tank, and (b) is a diagram showing a cleaning state of the biological filtration tank.

The normal processing method shown in FIG. 1A will be described. The biological filtration tank 4 is filled with the granular carrier 14 as a biological filtration layer, and the biological filtration layer is divided into two upper and lower sections at intervals, and an upper section R zone and a lower section F zone are formed. Porous members 45, 16, 18, 19 that do not pass through the granular carrier 2 above and below the section R zone and the lower section F zone.
And the air diffusion members 15 and 20 are respectively provided below the porous members 16 and 19 at the bottom of the upper section R zone and the lower section F zone, and a tank is provided between the porous members 16 and 18 that partition the upper and lower sections. A cleaning drainage pipe 17 for drawing out the internal treatment water into the first anaerobic filter bed tank 33 as washing drainage is provided, and an opening 22 communicating with the treatment water tank 21 is provided below the biological filtration tank 4.

The wastewater treatment method having the above-described configuration is performed as follows. The water 23 to be treated from the anaerobic filter tank second chamber 36 enters the upper zone R zone of the biological filtration layer 4.
The granular carrier 14 in the R zone is filled to the extent that it flows in the porous members 45 and 16 by air bubbles from the air diffusing member 15. The diffusing member 15 has a function of dissolving oxygen to diffuse R.
It is desirable to be arranged so as to be diffused throughout the zone. The to-be-treated water 23 entering the R zone is treated by the aerobic microorganisms inhabiting the granular carrier 14, and BOD decomposition and nitrification proceed. Further, SS is also captured and removed between the granular carriers 14. However, since the R zone is slowly flowing due to the air bubbles as described above, the SS is not completely captured. The passing water containing SS descends in the R zone and reaches the lower zone F zone. The particulate carrier 14 in the F zone is
It is necessary to fill air bubbles diffused from the diffusing member 20 only during washing, which will be described later, or to the extent that they flow by backwash water inserted from the opening 22.

The passing water that has reached the F zone is the granular carrier 14
Is formed as a filtration layer, the contained SS is trapped and removed between the granular carriers 14. Since the F zone is in a static state with respect to the R zone, the effect of removing SS is extremely high. Since dissolved oxygen is also carried over from the R zone, aerobic microorganisms also inhabit. If there is residual BOD that has not been completely decomposed in the R zone, it can be decomposed in the F zone. As described above, the water 23 to be treated is mainly B zone in the upper zone R zone.
OD is removed and nitrification also progresses.
S is removed and reaches the treated water tank 21 from the opening 22 and is discharged as treated water 24 from above. Biological filtration tank 4
As the treatment is continued, the particulate carrier 14 gradually becomes clogged by the SS captured in the biological filtration tank 4.
This tendency is remarkable in the lower zone F zone. Therefore, the biological filtration tank 4 needs to be washed.

Therefore, a method of cleaning the biological filtration tank 4 will be described with reference to FIG. When shifting from the normal processing to the cleaning, the air diffusion starts from the air diffusion member 20 below the lower section F zone. The air bubbles cause the particulate carrier 14 in the F zone.
Flows slowly and the trapped SS becomes liberated. At this time, the transfer pump 25 connected to the washing drainage pipe 17 between the R zone and the F zone is operated, and the treated water in the tank is drawn out into the first anaerobic filter bed tank 33 as washing drainage. Although the transfer pump 25 is shown as an air lift type, other means can be used. Then, as the water level in the biological filtration tank 4 decreases, the water level in the treated water tank 21 also decreases.
Therefore, the treated water 24 stored in the treated water tank 21 serves as the washing water 26 from the opening 22 at the lower part of the biological filtration tank to the lower section F.
Backflow into the zone. The washing water 26 rises in the F zone and is transferred to the anaerobic filter bed tank first chamber 33 from the washing drainage pipe 17 via the transfer pump 25 as washing wastewater 27 with SS released by air bubbles. At this time, since the water level in the R zone of the biological filtration tank 4 also decreases at the same time, the SS captured in the R zone is also transferred as the washing wastewater 27 due to the decrease in the water level. Therefore, the water level of the biological filtration tank 4 and the treated water 21 changes between the normal water level HWL and the water level LWWL after washing. The end of the cleaning is completed by stopping the air diffusion from the air diffusion member 20 below the F zone and stopping the transfer pump 25, and returns to the normal processing state. The lowered water level of the biological filtration tank 4 returns to the steady water level due to the inflow of the to-be-treated water 23, and the granular carriers 14 in the R zone and the F zone return to the original state. In the above-mentioned washing, the SS can be flown with an extremely small amount of air and an extremely small washing water washing speed and with a small amount of washing water. Therefore, the required power is small and economical.

Next, when the granular material used in the present invention is applied as a biological filtration tank, and when no porous member is used in the middle of the contact material C3 shown in FIG. 4, the boundary between the zone R zone and the lower zone F zone is used. Since the nearby granular carrier 14 moves up and down by the washing operation, the carrier amount in each zone may change from the set amount. Therefore, it is desirable to stabilize the filling amount of the granular carrier in each zone. That is, as shown in FIG. 1, the porous member 16 which allows the water 23 to pass through but does not allow the granular carrier 14 to pass above the air diffuser 15 at the boundary between the upper zone R zone and the lower zone F zone as shown in FIG.
Is achieved by a method that is provided horizontally horizontally. In addition, a porous member 18 that allows the water 23 to pass through but does not pass through the granular carrier 14 in the lower section is provided horizontally below the washing drainage pipe 17 so that the granular carrier 14 in the lower zone F zone can be washed. Is prevented from flowing out of the cleaning drainage pipe 17 together with the cleaning drainage 27. By applying the above method, the cleaning drainage can be easily extracted from both compartments. In the F zone, since SS is mostly removed in the upper layer, the SS separated from the upper layer is immediately pulled out from the cleaning drainage pipe 17 when cleaning starts, so that the cleaning efficiency is extremely high, and the amount of cleaning water is extremely high. It has the advantage of being small.

Next, the granular carrier to be filled in the biological filtration tank will be described. The characteristics required for the carrier are that the amount of microorganisms attached (retained amount) is large and that it can be easily washed.
It has physicochemical and mechanical durability. In a biological filtration tank, the amount of microorganisms adhering (retaining amount) to the carrier is often large in order to increase the treatment efficiency. Such a carrier has pores inside, and the pores communicate with each other. Granules are preferred. Alternatively, a fiber mass having voids such as between fibers is desirable. Examples of such inorganic carriers include perlite, shirasu balloon, foamed concrete, activated carbon, porous ceramics, and porous glass. Synthetic resin-based carriers include foamed products such as polyethylene, polyvinyl chloride, polyurethane, and polyvinyl alcohol acetal compounds, fiber bundles with irregularly entangled fibers, nonwoven fabrics with irregularly laminated fibers, and fiber bundles with fibers tied together. and so on.

However, in the washing of the biological filtration tank, it is necessary that excess microorganisms adhered to the carrier by bubbling or water flow and SS trapped between the carriers are easily separated. This has a great influence on the specific gravity of the carrier. Therefore, it is not preferable that the specific gravity of the carrier is too large or too small, and it is desirable that the carrier has a specific gravity of about 0.9 to 1.1. Many inorganic carriers have this point specific gravity too large. However, it can also be used by adjusting the specific gravity by increasing the porosity or other methods. On the other hand, for synthetic resin carriers, polyvinyl chloride, polyurethane,
Various kinds of fiber masses such as polyvinyl alcohol acetal compound and the above-mentioned fibers such as polyester and nylon have an appropriate specific gravity. Polyethylene has a small specific gravity in that respect. However, the specific gravity of polyethylene (here, indicating a communicating bubble) increases when microorganisms adhere thereto, and the specific gravity increases to 1.00.
An appropriate state of about 3 to 1.008 is obtained. Therefore, as the polyethylene communicating foam, microorganisms to which microorganisms are attached in advance can also be used. Alternatively, another specific gravity adjusting method is also possible. A method in which the emulsion paint is impregnated into the communicating foam and dried, or a method in which calcium carbonate, barium sulfate, or another specific gravity adjusting agent is added during foam molding of the carrier,
Further, there is a method in which a hydrophilic substance such as a polyethylene glycol ester or a glycerin fatty acid ester is added during foam molding of the carrier. As described above, a granular carrier having a specific gravity of approximately 0.9 to 1.1, which is a foamed molded product or a fibrous lump nonwoven fabric having open cells or voids between fibers in the carrier, is used.

[0030]

FIG. 2 shows an embodiment of a sewage purification tank according to the present invention which employs a biological filtration method comprising a carrier bed containing granular materials as described above. The present invention incorporates the biological filtration method described above into a septic tank. FIG.
2A is a plan view of the septic tank, and FIG. 2B is a cross-sectional view taken along line AA of FIG. 2A. The sewage purification tank 28 includes a partition wall 29,
30, 31 and 32, anaerobic filter bed first chamber 33
In the upper part, the contact portion 34 is stored in the upper part and the contact part 34 in the lower part,
Removal of coarse solids and reduction of the molecular weight of organic substances by anaerobic microorganisms are performed. Similarly, the contact material 35 is stored in the second chamber 36 of the anaerobic filter tank, and further efficiently decomposes organic matter. The biological filtration tank 4 has the configuration described with reference to FIG. 1, and stores the above-described granular carrier 14, and the inside of the tank 4 is functionally divided into an upper zone R zone and a lower zone F zone.
The main operation in each zone has already been described above, and will not be described. Air is inserted into the air diffuser 15 in a normal processing state, and air is inserted into the air diffuser 20 only during cleaning. The treated water tank 21 is in communication with the biological filtration tank 4 via the opening 22. The treated water tank 21 is provided to secure treated water as washing water. The disinfection tank 37 is provided to sterilize and discharge the treated water.

The transfer pump 38 is provided for transferring a part of the treated water in the treated water tank 21 to the first chamber 33 of the anaerobic filter bed tank. In the return of the treated water, an aerobic microbial reaction is performed in the biological filtration tank 4 and a large amount of nitrate nitrogen is contained. Therefore, the purpose is to remove nitrogen in the first anaerobic filter tank 33. The transfer pump 39 is provided in the first chamber 3 of the anaerobic filter bed tank.
3 is a pump for transferring the liquid passing through the filter bed to the upper part of the anaerobic filter bed tank second chamber 36. In the anaerobic filter bed tank first chamber 33, the water level fluctuates in the volume portion 44 above the contact material 34, and The anaerobic filter tank second chamber 36 is supplied with treated water 41 whose flow rate has been adjusted to the anaerobic filter tank second chamber 36 by combining with a transfer pump 39 so as to absorb the flow rate fluctuation of the water 40.

Here, the transfer pump 39 will be described by taking an air lift pump as an example. FIG. 3A shows the structure of a one-stage air lift pump, and FIG. 3B shows the structure of a two-stage air lift pump.
When the transfer pump 39 is a one-stage air lift pump, the anaerobic filter tank first chamber treated water 41 is transferred to the upper part of the anaerobic filter tank second chamber by the air supplied to the air pipe 42. Further, when the transfer pump 39 is a two-stage air lift pump, the anaerobic filter bed tank first chamber treated water 41 is transferred to the first-stage and second-stage connection parts by the air supplied to the air pipe 42, Next, the air is supplied to the air pipe 43 and transferred to the upper part of the second chamber of the anaerobic filter bed tank. The two-stage air lift pump
Even if the water level in the first chamber of the anaerobic filter tank changes between a low water level and a high water level, there is an advantage that a substantially constant pumping amount can be secured. In the ordinary fluctuation of the flow of wastewater from household merger, transfer pump 3
Reference numeral 9 denotes a single-stage air lift pump, which can obtain a flow rate adjusting characteristic, for example, a generally-known discharge coefficient of 2.5 to 3.5.
However, when it is desired to further improve the flow rate adjustment characteristics, a two-stage air lift pump is effective. In this case, a discharge coefficient of 1.5 to 2.5 is obtained.

The transfer pump 25 is provided to discharge the washing wastewater from the biological filtration tank 4 to the first biological filtration tank 33.
These transfer pumps are configured using an air lift pump, but are not limited to the air lift pump.

Here, the ordinary processing steps and operation of the sewage purification tank will be described. The water to be treated 40 is supplied from the inlet and enters the first chamber 33 of the anaerobic filter bed tank, where coarse solids are removed by the contact material 34 and at the same time anaerobic decomposition and denitrification by the returned treated water 24 are performed. Done. In the anaerobic filter tank 33, the water level fluctuates in the volume portion 44 above the contact material 34, and the fluctuation range (HWL to LWL) absorbs fluctuations in the flow rate of the water 40 to be treated. It has a volume that can be adjusted and has a flow rate adjustment function. The anaerobic filter tank treatment water 41 whose peak has been cut flows into the upper part of the anaerobic filter tank second chamber 36 by the transfer pump 39. Here, the organic matter is further decomposed and denitrified, and the treated water 23 in the second anaerobic filter bed tank is supplied to the biological filtration tank 4 by natural flow. Biological filtration tank 4
In the upper zone R zone, decomposition of organic matter and nitrification are performed by the action of aerobic microorganisms attached to the granular carrier 14 by air inserted from the air diffusing member 15, and part of SS is also captured. However, since the granular carrier in the R zone is flowing due to the rise of the air bubbles, the passing water containing the remaining SS descends in the lower zone F zone. In the F zone, since the granular carrier layer is in a stationary state, SS is sufficiently captured and removed. By this step, the water to be treated 40 is organic, SS,
Since nitrogen is also sufficiently removed, the treated water becomes highly treated water having a high degree of transparency and is transferred to the treatment water tank 21, sterilized in the disinfecting tank 37, and discharged out of the system as treated water 24.

Next, the cleaning step will be described. When the normal processing is continued, the biological filtration tank 4 needs to be cleaned because the filtration resistance gradually increases due to the capture of SS in the biological filtration layer, particularly in the lower section F zone. When the water level of the biological filtration tank 4 rises to a predetermined water level or when a predetermined time is reached by setting a timer, the cleaning instruction can be performed by the signal. In this case, the washing operation is performed in the first anaerobic filter tank.
It is desirable to perform the process when the water level in the chamber 33 is low (LWL), and it is usually preferable to set it at night when there is no inflow of the water 40 to be treated.

The cleaning is performed as follows. First, air diffusion from the air diffusion member 20 is started, and the F zone is bubbled.
At the same time, the transfer pump 25 is operated to pull out the SS separated by the air bubbles from the washing drainage pipe 17 together with the washing water as the washing drainage 27 and discharge it to the first chamber 33 of the anaerobic filter bed tank. The treated water No. 21 flows into the F zone as washing water. At the same time, the SS trapped in the R zone is also discharged to the first anaerobic filter tank 33 as washing water 27 as the water level falls. The amount of the carrier in each zone is not changed by the porous members 45, 16, 18, and 19. The end of the cleaning is completed by stopping the air diffusion from the air diffusion member 15 and stopping the transfer pump 25. It is sufficient that the amount of water necessary for washing is at least equal to or less than the volume of the R zone and the F zone of the biological filtration tank. After the completion of the washing, the anaerobic filter bed tank 2 returns to the normal processing state by the inflow of the treated water 23. By performing the above steps, it is possible to maintain advanced processing. Since the carrier 14 to be used has already been described, its description is omitted.

[0037]

According to the present invention, highly treated water having low BOD, efficient nitrification, low SS and high transparency can be stably obtained. In addition, the amount of washing wastewater can be suppressed to a small amount. Furthermore, since this biological filtration method is incorporated into a sewage purification tank to form an integral type, a small and high-performance sewage purification tank can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a sewage purification tank showing an embodiment of the present invention, where (a) shows a normal processing state and (b) shows a cleaning state.

FIG. 2A is a plan view showing an embodiment of the present invention,
(B) shows an AA sectional view of (a).

FIG. 3A is a cross-sectional view showing a structure of a one-stage air lift pump from the first chamber of the anaerobic filter tank to the second chamber of the anaerobic filter tank of the present invention, and FIG. FIG.

FIG. 4 is a sectional view of a sewage purification tank showing an example of a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Sewage purification tank 2 Anaerobic filter tank 1st chamber 3 Anaerobic filter tank 2nd chamber 4 Contact aeration tank (biological filtration tank) 5 Precipitation tank (treatment water tank) 6 Disinfection tank 7 Treated water 8 Treated water 9 Inlet 10 Outlet 11 Fixed-amount supply pump 12 Aeration tube for aeration 13 Backwash pump 14 Granular carrier 15 Air diffusion member 16 Porous member 17 Cleaning drainage drain tube 18 Porous member 19 Porous member 20 Air diffusion member 21 Treatment water tank 22 Opening 23 Treatment Water (Treated water in the anaerobic filter tank 2nd chamber) 24 Treated water 25 Transfer pump 26 Wash water 27 Wash drainage 28 Sewage purification tank 29 Partition wall 30 Partition wall 31 Partition wall 32 Partition wall 33 Anaerobic filter bed tank first chamber 34 Contact material 35 Contact material 36 Anaerobic filter bed tank second chamber 37 Disinfection tank 38 Transfer pump 39 Transfer pump 40 Treated water 41 Treated water in anaerobic filter tank first chamber 42 Air pipe 43 Air pipe 44 Volume 4 Porous member

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Masahiro Furuichi 1250 Shimoedori, Shimodate-shi, Ibaraki Pref.Hitachi Kasei Kogyo Co., Ltd.Housing Equipment Environment Division (72) Inventor Tsutomu Ishigaki 1250 Shimoedori, Shimodate-shi Shimodate-shi, Ibaraki Hitachi Kasei Kogyo Co., Ltd. Living Equipment Environment Division (56) References JP-A-6-71284 (JP, A)

Claims (1)

(57) [Claims] 1. A sewage purification tank for purifying a tank by partitioning the inside of the tank with a partition wall and sequentially purifying water to be treated into these tanks, wherein the plurality of tanks are anaerobic filter beds. The first chamber, the second chamber, the biological filtration tank, the treatment water tank, and the disinfecting tank are arranged in this order, and a volume section having a flow control function is provided at the upper part of the first chamber of the anaerobic filter bed tank. Is transferred to the upper part of the second anaerobic filter bed tank at the subsequent stage and allowed to flow down, and is allowed to flow naturally from the bottom of the second chamber to the upper part of the biological filter tank at the subsequent stage. The biological filter tank is a filter bed containing particulate matter. And separating the biological filtration layer into two upper and lower compartments at an interval to form an upper compartment and a lower compartment, and providing a porous member horizontally and transversely above and below the upper compartment and the lower compartment. And a diffuser member provided below the porous member at the bottom of the lower section to partition the upper and lower sections. The treated water in the tank is drawn out from the washing drainage pipe as washing water into the first chamber of the anaerobic filter bed tank, and the passing liquid flowing down the biological filtration tank in a downward flow is transferred from the bottom of the biological filtration tank to the treatment water tank. A sewage purification tank wherein the liquid is discharged outside the system after reaching the disinfection tank from the upper part of the treatment water tank, and the liquid in the tank is returned to the first chamber of the anaerobic filter bed tank.