JPH06285484A - Soil water purifying tank - Google Patents

Abstract

PURPOSE:To prepare good treated water continuously and stably, reduce the amount of cleaning water and make a tank small by drawing treated water in a biological filter tank as cleaning drainage out of a cleaning drainage pipe and transferring the passing liquid in the biological filter tank to a treated water tank and also to a disinfection tank and discharging to the outside of a system. CONSTITUTION:In a soil water purifying tank, a biological filter tank 4 is provided with a filter bed for storing granular materials, and the filter bed is divided into an upper zone R and a lower zone F separated up and down, and porous components 19 are placed in a manner of horizontally crossing respectively, while air diffusion components 15 and 20 are disposed below the porous components 19 at the bottoms of upper and lower divided zones R and F respectively. The inner-tank treated water is drawn from a cleaning drainage pipe 17 between the porous components 19 driving the upper and lower zones R and F into an anaerobic filter bed tank first chamber as cleaned drainage, and the passing liquid flowing down in the form of downward flow through the biological filter tank 4 is transferred from the bottom of the biological filter tank 4 to a cleaned water tank 21 and flowed from the upper section to the disinfection tank to be discharged to the outside of a system. The inner- tank liquid is returned from the treated water tank 21 to the anaerobic filter bed tank first chamber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sewage purification tank which adopts a biological filtration method using a granular carrier to purify combined wastewater discharged from homes and the like.

[0002]

2. Description of the Related Art A conventional septic 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 has an anaerobic filter tank first chamber partitioned by partition walls A1 ... A4. 2. The anaerobic filter bed tank second chamber 3, the contact aeration tank 4, the settling tank 5, and the disinfecting tank 6, and the treated water 7 supplied from the inflow port 9 is transferred from the anaerobic filter bed tank first chamber 2 The water is sequentially transferred, and finally passes through the disinfecting tank 6 and is discharged as treated water 8 from the outlet 10.

The anaerobic filter bed first chamber 2, the second chamber 3 and the contact aeration tank 4 are filled with contact materials C1 ... C3 for implanting microorganisms that decompose organic pollutants. . Since it is desirable that the contact materials C1 ... C3 have a large specific surface area (m ² / m ³ ), corrugated plate-shaped, honeycomb-shaped, or net-shaped materials are used.

In the contact aeration tank 4, biological sludge converted from organic pollutants (hereinafter referred to as SS) or peeling sludge due to peeling of biofilm from the contact material C3 is generated, and the SS and peeling sludge are precipitated in the subsequent stage. Specific gravity is separated in the tank 5 by a precipitation method.

Another conventional example is disclosed in Japanese Patent Laid-Open No. 64-75095, which is an improved version of the well-known conventional sewage purification tank 1, and is disclosed in Japanese Patent Laid-Open No. 64-75095.
The configuration of the sewage purification tank disclosed in Japanese Patent Publication No. 95 is substantially the same as that of the conventional example described above, and therefore will be described in detail with reference to FIG.

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

In the biological filtration tank 4, the organic pollutants contained in the water 7 to be treated are converted into SS by the microorganisms adhering to the contact material C3, and this SS is converted by the contact material C3 by the sieving filtration method. It is filtered and captured.

The organic pollutant is biodegraded aerobically in the biological filter tank 4 due to the combined effect of the biofilm of the microorganisms attached to the contact material C3 and the SS captured by the contact material C3.

The above-mentioned method for decomposing organic pollutants is usually called a biological filtration method in the water treatment field.

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

In the sewage purification tank 1, the treated water 7 enters the anaerobic filter bed tank first chamber 2 through the inflow port 9 and, after removing large dusts and foreign substances, enters the anaerobic filter bed tank second chamber 3. enter.

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

Next, the water 7 to be treated enters the biological filtration tank 4 from the second chamber 3 of the anaerobic filter tank by the constant amount supply pump 11, and is aerobically treated in the biological filtration tank 4, so that air is discharged. Is performed from the aeration diffuser 12.

Therefore, the SS trapped in the biological filtration tank 4 and the biofilm attached to the contact material C3 aerobically biodegrade the organic pollutants.

In the biological filtration tank 4, the water to be treated 7 from which the organic pollutants are decomposed and the SS is removed reaches the treated water tank 5, is further sterilized in the disinfection tank 6, and is discharged from the outlet 10 as treated water 8. To be done.

When 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. The contact material C3 is backwashed regularly.

As 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, the backwashed water is taken out from the upper portion and returned to the anaerobic filter bed first chamber 2. (Not shown).

[0019]

However, the conventional sewage purification tank as described above has the following problems. (1) The settling tank 5 in the well-known conventional example sewage purification tank 1
However, due to the fluctuation of the flow rate of the treated water 7 or the influence of the seasonal water temperature change, it is not possible to deal with this fluctuation only by the gravity separation by the precipitation method, and the treated water 8 contains a large amount of SS. It becomes cloudy. (2) In the sewage purification tank 1 disclosed in Japanese Patent Laid-Open No. 64-75095, which is an improvement of the above-mentioned conventional example, the biological filtration tank 4 has a physical filtration function and a biological decomposition function.
It is necessary to fill with a small granular contact material C3 of about m or less, so that clogging is likely to occur and the time during which filtration can be continued is short. (3) Further, since the biological filtration tank 4 fulfills the above-mentioned two functions, the tank volume becomes large, so that it becomes difficult to carry out backwashing over the entire tank, and the filtering action is deteriorated. (4) Further, since the amount of backwash water is usually required to be equal to or larger than that of the biological filtration tank 4, the amount of backwash water becomes large when the tank is large.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a small-sized sewage purification tank in which good treated water can be obtained continuously and stably and the amount of washing water is reduced. .

[0021]

In order to achieve the above object, the present invention forms a plurality of treatment tanks by partitioning the inside of the tank with a partition wall, and the water to be treated is sequentially admitted to these treatment tanks for purification. In the sewage purification tank that performs, the plurality of treatment tanks are arranged in the order of the anaerobic filter bed tank first chamber, the second chamber, the biological filter tank, the treated water tank, and the disinfection tank, and the flow rate is adjusted above the anaerobic filter bed tank first chamber. A volume having a function is provided, and the liquid passing through the first chamber of the anaerobic filter bed tank is transferred to the upper part of the second chamber of the anaerobic filter bed tank of the latter stage to flow down and the natural liquid flows from the bottom of the second chamber to the upper part of the biological filter tank of the latter stage. The biological filtration tank has a filter bed containing granular materials, and the biological filtration layer is separated into two upper and lower compartments at intervals to form an upper compartment and a lower compartment. A porous member is provided horizontally across the top and bottom, and the bottom of the upper and lower sections is below the porous member. A diffuser member is provided for each of the upper and lower compartments, and the treated water in the tank is drawn out from the cleaning wastewater discharge pipe between the porous members, which separates the upper and lower compartments, to the first chamber of the anaerobic filter bed tank as the cleaning wastewater, and the biological filtration tank is allowed to flow downward. The flowed-through liquid is transferred from the bottom of the biological filtration tank to the treated water tank, and is discharged to the outside of the system after reaching the disinfection tank from the upper portion of the treated water tank. Characterized by returning to one room.

First, a method of treating wastewater by a biological filtration method using a granular material 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.

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

The wastewater treatment method having the above-described structure is performed as follows. The treated water 23 from the anaerobic filter bed second chamber 36 enters the upper section R zone of the biological filtration layer 4.
The granular carrier 14 in the R zone is filled with air bubbles from the air diffusing member 15 so as to flow within the porous members 45 and 16. In addition, the aeration member 15 causes dissolved oxygen to be R by the aeration.
It is desirable that they are arranged so that they are diffused throughout the zone. The water 23 to be treated that has entered 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 by the air bubbles as described above, the capture of SS is not perfect. The passing water containing SS descends from the R zone and reaches the lower section F zone. The granular carrier 14 in the F zone is
It is necessary to fill the air bubbles diffused from the diffuser member 20 and the backwash water inserted from the opening 22 to such a degree that the air bubbles can flow only during the later-described washing.

The passing water reaching the F zone is the granular carrier 14
Is formed as a filter 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. Further, since dissolved oxygen is also carried over from the R zone, aerobic microorganisms also inhabit, and if there is residual BOD that has not been completely decomposed in the R zone, it can be decomposed in this F zone. In this way, the treated water 23 is mainly B in the upper zone R zone.
OD is removed and nitrification progresses, and S mainly in the lower zone F zone
S is removed and reaches the treated water tank 21 through the opening 22 and is discharged as treated water 24 from the upper portion thereof. Biological filtration tank 4
As the treatment is continued, the granular carrier 14 becomes gradually clogged by the SS captured in the biological filtration tank 4.
This tendency is remarkable in the F zone of the lower section. 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 normal processing to cleaning, air diffusion is started from the air diffusion member 20 below the lower section F zone. By this air bubble, the granular carrier 14 in the F zone
Flow slowly and the captured SS becomes free. At this time, the transfer pump 25 connected to the cleaning drainage pipe 17 between the R zone and the F zone is operated to draw the treated water in the tank to the anaerobic filter bed first chamber 33 as cleaning drainage. The transfer pump 25 is of the air lift type, but other means is also possible. 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 is used as washing water 26 from the opening 22 at the bottom of the biological filtration tank to the lower section F.
Backflow into the zone. The cleaning water 26 rises in the F zone and is transferred from the cleaning drainage discharge pipe 17 to the anaerobic filter bed first chamber 33 through the transfer pump 25 as the cleaning drainage 27 along with SS released by the air bubbles. At this time, the water level in the R zone of the biological filtration tank 4 is also lowered at the same time, so that the SS captured in the R zone is also transferred as the cleaning drainage 27 due to the water level lowering. Therefore, the water levels of the biological filtration tank 4 and the treated water 21 change between the normal water level H · W · L and the water level L · W · L after washing. The end of cleaning is completed by stopping the air diffusion from the air diffusion member 20 on the lower side of the F zone and stopping the transfer pump 25 to return 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 water to be treated 23, and the granular carriers 14 in the R zone and the F zone return to their original state. In the above washing, SS can be flowed with an extremely small amount of air and an extremely small amount of washing water and with a small amount of washing water. Therefore, the required power is small and it is economical.

Next, when the granular material used in the present invention is applied as a biological filtration tank, when a porous member is not used in the middle of the contact material C3 shown in FIG. 4, the boundary between the section R zone and the lower section F zone. Since the granular carrier 14 in the vicinity 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 the method, as shown in FIG. 1, the porous member 16 that allows the treated water 23 to pass through but not the granular carrier 14 above the diffuser member 15 at the boundary between the upper section R zone and the lower section F zone.
It is achieved by the method of installing horizontally. In addition, a porous member 18 that allows the water to be treated 23 to pass through but does not allow the granular carrier 14 in the lower compartment to pass through is provided below the cleaning wastewater discharge pipe 17 in a horizontal crossing manner, so that the granular carrier 14 in the F zone in the lower partition at the time of cleaning. Are prevented from flowing out of the cleaning drainage pipe 17 together with the cleaning drainage 27. By applying the above method, the cleaning waste water can be easily withdrawn from both compartments. Further, in the F zone, since most of the SS is removed in the upper layer portion, the SS separated from the upper layer portion is immediately withdrawn from the cleaning drainage pipe 17 when the cleaning is started, so that the cleaning efficiency is extremely high and the amount of the cleaning water is also large. It has the advantage of being few.

Next, the carrier for the granular material to be filled in the biological filtration tank will be described. The characteristics required for the carrier are that the amount of microorganisms attached (retention amount) is large and that it can be easily washed.
It has physicochemical and mechanical durability. In the biological filtration tank, in order to improve the treatment efficiency, it is preferable that the amount of microorganisms attached to the carrier (retention amount) is large, and such a carrier has pores inside and the pores communicate with each other. Granules that are present are desirable. Alternatively, a fiber mass with voids such as between fibers is desirable. Examples of such inorganic carriers include pearlite, shirasu balloon, foam concrete, activated carbon, porous ceramics, and porous glass. Synthetic resin carriers include foamed molded products such as polyethylene, polyvinyl chloride, polyurethane, polyvinyl alcohol acetal compounds, fiber lumps in which fibers are randomly entangled, non-woven fabrics in which fibers are randomly laminated, and fiber lumps in which fibers are bound together. and so on.

However, in the cleaning of the biological filtration tank, it is necessary that the carrier easily peels off excess microorganisms attached to the carrier by bubbling or water flow and SS trapped between the carriers. The specific gravity of the carrier has a great influence on this. Therefore, the carrier is not preferable if its specific gravity is too large or too small, and a carrier having a specific gravity of approximately 0.9 to 1.1 is desirable. Many inorganic carriers have too large a point specific gravity. However, it can also be used by adjusting the specific gravity by increasing the porosity or by another method. On the other hand, synthetic resin carriers include polyvinyl chloride, polyurethane,
The polyvinyl alcohol acetal compound, the above-mentioned fibers, and various fiber lumps such as polyester and nylon have an appropriate specific gravity. In that respect, polyethylene has a small specific gravity. However, the specific gravity of polyethylene (which refers to open cells here) increases as microorganisms adhere to it, resulting in 1.00
It becomes a proper state of about 3 to 1.008. Therefore, as the polyethylene open-cell foam, it is also possible to use one to which microorganisms have been attached in advance. Alternatively, another specific gravity adjusting method is possible. A method of impregnating an open paint with an emulsion paint and drying, or a method of adding calcium carbonate, barium sulfate or other specific gravity adjusting agent during foam molding of a carrier,
Further, there is a method of adding a hydrophilic substance such as polyethylene glycol ester or glycerin fatty acid ester at the time of foam molding of the carrier. As described above, a granular carrier having a specific gravity of 0.9 to 1.1 is used, such as a foamed molded product having communication cells or voids between fibers, a fiber lump nonwoven fabric, or the like.

[0030]

EXAMPLE An example of the sewage purification tank of the present invention incorporating the biological filtration method comprising a carrier bed containing the above-mentioned granular materials will be described with reference to FIG. The present invention incorporates the above-mentioned biological filtration method into a septic tank. Figure 2
2A is a plan view of the septic tank, and FIG. 2B is a sectional view taken along the line AA of FIG. The septic tank 28 has a partition wall 29,
Separated by 30, 31, 32, anaerobic filter bed first chamber 33
Holds the volume 44 in the upper part and the contact material 34 in the lower part,
Coarse solids are removed and anaerobic microorganisms are used to reduce the molecular weight of organic substances. Similarly, the contact material 35 is housed in the second chamber 36 of the anaerobic filter bed tank, and further decomposes organic substances efficiently. The biological filtration tank 4 has the structure described in FIG. 1, the above-mentioned granular carrier 14 is housed therein, and the inside of the tank 4 is functionally divided into an upper section R zone and a lower section F zone.
The main operation in each zone has already been described as above, and will be omitted. 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 through the opening 22. The treated water tank 21 is provided to secure treated water as washing water. The disinfection tank 37 is provided for sterilizing the treated water and discharging it.

The transfer pump 38 is provided to transfer a part of the treated water in the treated water tank 21 to the anaerobic filter bed first chamber 33. The return of the treated water is intended to remove nitrogen in the anaerobic filter bed first chamber 33 because the biological filter tank 4 carries out aerobic microbial reaction and contains a large amount of nitrate nitrogen. The transfer pump 39 is the anaerobic filter bed first chamber 3
3 is a pump for transferring the liquid passing through the filter bed of No. 3 to the upper part of the anaerobic filter bed tank second chamber 36, and the water level of the anaerobic filter bed tank first chamber 33 is changed in the volume portion 44 above the contact material 34, and the treated material is treated. The anaerobic filter bed tank first chamber treated water 41 having the adjusted flow rate is supplied to the anaerobic filter bed tank second chamber 36 by combining with the transfer pump 39 so that the fluctuation of the flow rate of the water 40 can be absorbed.

Here, the transfer pump 39 will be described by taking an air lift pump as an example. 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 bed first chamber treated water 41 is transferred to the upper part of the anaerobic filter bed second chamber by the air supplied to the air pipe 42. When the transfer pump 39 is a two-stage air lift pump, the anaerobic filter bed first chamber treated water 41 is transferred by the air supplied to the air pipe 42 to the first and second connecting portions, Next, the air supplied to the air pipe 43 transfers the air to the upper part of the second chamber of the anaerobic filter bed tank. The two-stage air lift pump is
Even if the water level in the first chamber of the anaerobic filter bed tank changes from a low water level to a high water level, there is an advantage that a substantially constant pumping amount can be secured. In the case of fluctuations in the flow rate of normal household merged wastewater, transfer pump 3
Reference numeral 9 is a one-stage air lift pump, and a flow rate adjusting characteristic, for example, an emission coefficient which is usually said to be 2.5 to 3.5 can be obtained.
However, when it is desired to further improve the flow rate adjusting characteristic, the two-stage air lift pump is effective, and in this case, the emission coefficient of 1.5 to 2.5 can be obtained.

The transfer pump 25 is provided to discharge the cleaning wastewater of the biological filtration tank 4 to the biological filtration tank first chamber 33.
Although these transfer pumps are configured to use air lift type pumps, they are not limited to air lift type pumps.

Here, the normal processing steps and actions of the sewage purification tank will be described. The water to be treated 40 is supplied from the inflow port, enters the first chamber 33 of the anaerobic filter bed, and coarse solids are removed by the contact material 34, and at the same time anaerobic decomposition and denitrification by the treated water 24 returned as described above. Done. In the anaerobic filter bed 33, the water level fluctuates in the volume 44 above the contact material 34, and the fluctuation range (HWL to LWL) absorbs the fluctuation in the flow rate of the water 40 to be treated. It has a volume that allows it to have a flow rate adjusting function. The transfer pump 39 causes the peak-cut anaerobic filter bed treated water 41 to flow into the upper part of the anaerobic filter bed second chamber 36. Here, organic substances are further decomposed and denitrified, and the anaerobic filter bed second chamber treated water 23 is supplied to the biological filter tank 4 by natural flow. Biological filtration tank 4
Then, in the upper section R zone, the organic substances are decomposed and nitrified by the action of the aerobic microorganisms adhering to the granular carrier 14 by the air inserted from the air diffusing member 15, and SS is also partially captured. However, since the granular carrier in the R zone is flowing due to the rise of air bubbles, the passing water containing the residual SS descends in the lower section F zone. In the F zone, SS is sufficiently trapped and removed because the granular carrier layer is stationary. By this step, the water 40 to be treated is organic matter, SS,
Since nitrogen is also sufficiently removed, it becomes highly treated water with high transparency, moves to the treated water tank 21, and is discharged outside the system as post-treated water 24 that has been sterilized in the disinfection tank 37.

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

The cleaning is performed as follows. First, start air diffusion from the air diffusion member 20, bubble the F zone,
At the same time, the transfer pump 25 is operated to draw out the SS separated by the air bubbles together with the cleaning water from the cleaning drainage discharge pipe 17 as the cleaning drainage 27 and discharge the SS into the anaerobic filter bed first chamber 33, and from the opening 22 to the treated water tank. The treated water of 21 is made to flow into F zone as wash water. At the same time, the SS trapped in the R zone is discharged to the anaerobic filter bed first chamber 33 as the cleaning drainage 27 as the water level lowers. The amount of carrier in each zone does not change due to the porous members 45, 16, 18, and 19. The cleaning is completed by stopping the air diffusion from the air diffusion member 15 and stopping the transfer pump 25. It is sufficient to supply the amount of water required for cleaning at least equal to or less than the volumes of the R zone and the F zone of the biological filtration tank. After the cleaning is completed, the anaerobic filter bed second chamber treated water 23 flows in to restore the normal treatment state. By performing the above steps, it becomes possible to maintain a high level of processing. Since the carrier 14 used has already been described, the description thereof will be omitted.

[0037]

According to the present invention, highly treated water having low BOD, efficient nitrification, low SS and a transparent feeling can be stably obtained. In addition, the amount of cleaning wastewater can be reduced to a small amount. Furthermore, since this biological filtration method is incorporated into a sewage purification tank to form an integrated type, it is possible to provide a compact and high-performance sewage purification tank.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a wastewater purification tank showing an embodiment of the present invention, in which (a) shows a normal treatment state and (b) shows a washing state.

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

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

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

[Explanation of symbols]

1 Sewage Purification Tank 2 Anaerobic Filter Bed Tank 1st Room 3 Anaerobic Filter Bed Tank 2nd Room 4 Contact Aeration Tank (Biological Filter Tank) 5 Sedimentation Tank (Treatment Water Tank) 6 Disinfection Tank 7 Treated Water 8 Treated Water 9 Inlet 10 Outlet 11 Fixed-quantity supply pump 12 Aeration diffuser 13 Backwash pump 14 Granular carrier 15 Diffuser 16 Porous member 17 Wash drainage pipe 18 Porous member 19 Porous member 20 Diffuser 21 Treated water tank 22 Opening 23 Treated Water (anaerobic filter bed second chamber treated water) 24 Treated water 25 Transfer pump 26 Cleaning water 27 Cleaning drainage 28 Sewage purification tank 29 Partition wall 30 Partition wall 31 Partition wall 32 Partition wall 33 Anaerobic filter bed first chamber 34 Contact material 35 Contact material 36 Anaerobic filter bed second chamber 37 Disinfection tank 38 Transfer pump 39 Transfer pump 40 Treated water 41 Anaerobic filter bed first chamber treated water 42 Air pipe 43 Air pipe 44 Volume 4 Porous member

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiro Furuichi 1250 Shimoeden, Shimodate-shi, Ibaraki Pref.Hitachi Chemical Industry Co., Ltd.Sumiki Environment Division (72) Tsutomu Ishigaki 1250 Shimoeden, Shimodate-shi, Ibaraki Prefecture Hitachi Chemical Co., Ltd.

Claims (1)

[Claims] 1. A sewage purification tank in which a plurality of treatment tanks are formed by partitioning the inside of the tank with partition walls, and the water to be treated is sequentially admitted to these treatment tanks for purification, and the plurality of treatment tanks are anaerobic filter beds. The first chamber of the anaerobic filter tank is arranged in the order of the first chamber of the tank, the second chamber, the biological filtration tank, the treated water tank, and the disinfection tank, and a volume section having a flow rate adjusting function is provided above the first chamber of the anaerobic filter tank. Is passed to the upper part of the second chamber of the anaerobic filter bed tank of the subsequent stage to flow down, and is allowed to naturally flow from the bottom of the second chamber to the upper part of the biological filter tank of the subsequent stage, and the biological filter tank contains a filter bed containing particulate matter. The upper section and the lower section are formed by separating the biological filtration layer into two sections, the upper section and the lower section, and the porous member is provided horizontally across the upper and lower sections of the upper section and the lower section, as well as the upper section. And a porous member for partitioning the upper and lower compartments, respectively, with air diffusers provided below the porous member at the bottom of the lower compartment The treated water in the tank is drawn out to the first chamber of the anaerobic filter bed tank as the cleaning wastewater from the cleaning wastewater discharge pipe between the two, and the passing liquid flowing down the biological filter tank in the downward flow is transferred from the bottom of the biological filter tank to the treated water tank. A sewage purification tank characterized by being discharged from the system after reaching the disinfection tank from the upper part of the treated water tank, and returning the solution in the tank to the first chamber of the anaerobic filter bed tank to the treated water tank.