JP2010234342A - Septic tank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide smaller septic tanks of which the inspection and maintenance can be sufficiently carried out. <P>SOLUTION: While a first end plate B1 and a second end plate B2 having curved surfaces projected outside to both ends of a body are installed in the septic tank 1, a space for treating water is arranged inside the body of the septic tank 1. The space for treating water is divided, in order of treatment, into a pretreating tank constituted of an anaerobic tank N or an aerobic tank, an aerobic tank, a biological-membrane-filtering tank, a water treating tank, a disinfection tank, and a discharge pump tank through a partition walls separately. A plurality of inspection openings H are installed above the tanks, the pretreating tank is arranged inside the first end plate B1 of the one end in the space for treating water, the aerobic tank is arranged inside the second end plate B2 of the other end, and the biological-membrane-filtering tank, the water treating tank, the disinfection tank, and the discharge pump tank are arranged between the pretreating tank and the water treating tank. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention provides a first end plate and a second end plate having curved surfaces protruding outward at both end portions of a cylindrical body, and has a water treatment space inside the septic tank body. Space is divided into anaerobic treatment tank, aerobic treatment tank, biofilm filtration tank, treated water tank, disinfection tank, and discharge pump tank in the order of treatment, and is partitioned separately through a partition wall. The present invention relates to a septic tank provided with a mouth.

  Conventionally, an anaerobic treatment tank, an aerobic treatment tank, a biofilm filtration tank, a treatment water tank, a disinfection tank, and a discharge pump tank are arranged in the order of treatment from the inside of the first end plate to the inside of the second end plate in the water treatment space. It is common to arrange them in the longitudinal direction of the cylindrical body (see, for example, Patent Document 1 or Patent Document 2).

JP 2002-346591 A JP 7-124578 A

In the conventional septic tank described above, there is a problem that the whole tends to be long and large when the body is to be treated with a large capacity and a large diameter in order to increase the water treatment capacity.
In addition, the plurality of inspection ports must be arranged so that each tank can be inspected and maintained, and an inspection manhole of a certain size is required above each tank. The size becomes unnecessarily large.
Therefore, for example, a pair of a biofilm filtration tank and a treatment water tank arranged in the radial direction of the septic tank body, and a pair of a disinfection tank and a discharge pump tank arranged in the radial direction of the septic tank body, It is possible to reduce the overall length by arranging them in the longitudinal direction of the main body.
However, even if one set of the disinfection tank and the discharge pump tank is arranged in the radial direction and one inspection port is arranged, when these tanks are arranged inside the second end plate, the second end plate is Since the inspection surface has a curved surface protruding outward, the inspection port is disposed more inside than the second end plate in plan view, and the inspection port has a size that allows the pump in the discharge pump tank to be taken in and out for maintenance. For this reason, the disinfection tank and the discharge pump tank have an unnecessarily large capacity, and there is a limit to downsizing.

  Accordingly, an object of the present invention is to provide a septic tank that solves the above-mentioned problems and is smaller and that can sufficiently inspect and maintain each tank.

The first characteristic configuration of the present invention includes a first end plate and a second end plate having curved surfaces protruding outward at both ends, and a water treatment space inside the septic tank body, Separately formed through partition walls in pretreatment tanks, aerobic treatment tanks, biofilm filtration tanks, treated water tanks, disinfection tanks, and discharge pump tanks, where treatment spaces consist of anaerobic treatment tanks or aerobic treatment tanks in the order of treatment And a septic tank provided with a plurality of inspection ports above the tanks,
A pretreatment tank is disposed inside the first end plate at one end in the water treatment space,
An aerobic treatment tank is arranged inside the second end plate at the other end,
Between the pretreatment tank and the aerobic treatment tank, the biofilm filtration tank, the treated water tank, the disinfection tank, and the discharge pump tank are disposed.

According to the first characteristic configuration of the present invention, in order to increase the water treatment capacity of the entire septic tank, the pretreatment tank and the aerobic treatment tank must have large capacities. In the water treatment space, the pretreatment tank is arranged inside the first end plate at one end, and the aerobic treatment tank is arranged inside the second end plate at the other end, thereby securing an appropriate treatment space. In addition, even if the inspection port for the pretreatment tank and the inspection port for the aerobic treatment tank are arranged on the inner side of the first and second end plates, respectively, the inspection work and maintenance are not hindered.
Moreover, by arranging the biofilm filtration tank, the treated water tank, the disinfection tank, and the discharge pump tank between the pretreatment tank and the aerobic treatment tank, the size and arrangement of the tanks can be further increased. The capacity can be designed more appropriately, and the inspection port for each tank can be arranged without being affected by the end plate having a curved surface.
Accordingly, it is possible to further reduce the size of the entire septic tank.

  In the second characteristic configuration of the present invention, the biofilm filtration tank and the treated water tank are arranged in the radial direction of the septic tank body, and the disinfection tank and the discharge pump tank are arranged in the longitudinal direction of the septic tank body. It exists in the place arrange | positioned beside the radial direction of a treated water tank.

According to the 2nd characteristic structure of this invention, in addition to being able to achieve the above-mentioned effect by the 1st characteristic structure of this invention, the said biofilm filtration tank, the said treated water tank, the said disinfection tank, Since the discharge pump tank can secure an appropriate capacity, and these tanks are concentrated in the central portion in the radial direction of the septic tank main body, it is only necessary to provide one inspection port on the upper part. The replenishment of the chemicals and the work of taking in and out the discharge pump in the discharge pump tank can be performed through the inspection port without any trouble.
Therefore, it is possible to perform inspection and maintenance without hindrance while enabling further downsizing.

  A third characteristic configuration of the present invention is that the pretreatment tank is an anaerobic treatment tank, and is a partition wall that partitions in the longitudinal direction of the septic tank body in the partition wall, and the biofilm filtration tank, the treated water tank, The anaerobic treatment tank and the aerobic treatment tank are partitioned with respect to the disinfection tank and the discharge pump tank.

According to the third characteristic configuration of the present invention, the anaerobic treatment tank and the aerobic treatment tank that must have a large capacity in order to increase the water treatment capacity are partitioned by the partition wall that partitions the water treatment space into the longitudinal method of the septic tank body. The biofilm filtration tank, the treated water tank, the disinfection tank, and the discharge pump tank are formed between the partition walls and the partition walls, so that the partition walls that partition these tanks are the partition walls that partition the body portion in the longitudinal direction. Does not require strength.
Therefore, it is possible to improve the assembling property while maintaining the strength of the entire septic tank.

It is the vertical side surface schematic diagram of the septic tank which comprises the sewage treatment apparatus of this invention. FIG. FIG. 3 is a sectional view taken along line III-III in FIG. 2. It is IV-IV sectional drawing in FIG. It is a principal part cross-sectional plan view of another embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

  As shown in FIGS. 1 to 4, the septic tank constituting the sewage treatment apparatus of the present invention comprises a first stencil plate B <b> 1 and a second stencil plate B <b> 2 having curved surfaces protruding outward at both ends of the cylindrical body. The main body 1 has a water treatment space inside the septic tank body 1, and the water treatment space is an anaerobic treatment tank N from the upstream side, a carrier flow tank E1 as an aerobic treatment tank, and a carrier filtration as a biofilm filtration tank. A tank E2, a treated water tank T1, a disinfection tank Q, and a discharge pump tank S are provided. A solid-liquid separation tank N1 and an anaerobic filter bed tank N2 are provided as the anaerobic treatment tank N, and are partitioned separately through a partition wall. . Of the partition walls, the biofilm filtration tank, the treated water tank T1, the disinfection tank Q, and the discharge pump tank S are separated from the solid-liquid separation tank N1, the anaerobic filter bed tank N2, and the carrier flow tank E1. The first partition wall W1, the second partition wall W2, and the third partition wall W3 are provided as partition walls that are partitioned in the longitudinal direction, and a plurality of inspection ports H1 to H6 are provided above the tanks.

  The raw water to be treated flows into the solid-liquid separation tank N1 from the raw water inflow section I and is decomposed while being transferred downstream in the order of the anaerobic filter bed tank N2, the carrier flow tank E1, the carrier filtration tank E2, and the treated water tank T1. Then, after passing through the disinfection tank Q and the discharge pump tank S, it is discharged from the discharge port Z to the outside of the tank.

The solid-liquid separation tank N1 is formed by providing a water treatment space for receiving and temporarily storing the treated water flowing in from the treated water inflow port I and precipitating and separating impurities. Floating matters and solids in the raw water to be treated that have flowed into are separated by precipitation and stored as scum at the top of the solid-liquid separation tank N1 or as sludge at the bottom.
Moreover, the said solid-liquid separation tank N1 and the said anaerobic filter bed tank N2 are provided with the comparatively big storage capacity, and have the flow volume adjustment part R which can adjust a flow volume in the range of LWL-HWL. Thereby, since it is the structure which absorbs the peak amount of the inflow processing water amount concentrated on the morning and evening specific time etc., it contributes to stabilization of the processing performance of the downstream carrier fluid tank E1 and the carrier filtration tank E2.

  It is good also as an anaerobic filter bed tank which provided the anaerobic filter bed instead of the said solid-liquid separation tank N1. At this time, anaerobic microorganisms can be grown inside the anaerobic filter bed. The raw water to be treated which flows into the anaerobic filter bed tank is stored in the anaerobic filter bed tank and is anaerobically decomposed, and mainly coarse organic matter is subdivided. Solids such as sludge that are not easily decomposed are stored as precipitates in the lower part of the anaerobic filter bed tank or as scum in the upper part of the anaerobic filter bed tank.

  The anaerobic filter bed tank N2 includes an anaerobic filter bed F, and is configured to fix and grow anaerobic microorganisms on the anaerobic filter bed F. The water to be treated that has flowed into the anaerobic filter bed tank N2 is further subjected to anaerobic treatment, decomposed to a state where there is almost no solid matter, and then transferred to the carrier fluid tank E1 via the flow rate adjusting air lift pump A1.

  As an anaerobic treatment tank, it is also possible to provide a flow rate adjusting tank instead of the solid-liquid separation tank N1 and the anaerobic filter bed tank described above to absorb the peak amount of the water to be treated in the entire tank.

The carrier fluid tank E1 accommodates and holds a carrier C1 that is formed so as to be able to flow together with the water to be treated in a state where microorganisms are supported, and is a dispersion connected to an air supply pipe for fluidizing the carrier by supplying bubbles. A trachea D1 is provided to provide an air diffuser, and the carrier C1 is allowed to flow in the carrier fluid tank E1 by supplying bubbles from the air diffuser. With such a configuration, the water to be treated flowing into the carrier fluid tank E1 is purified by aerobic decomposition by aerobic microorganisms.
If the carrier C1 has an uneven surface shape, the carrier C1 has a preferable shape for supporting a biofilm on the surface of the carrier C1.

The carrier filtration tank E2 is configured by filling a carrier C2 having a specific gravity greater than that of water to a predetermined height at a high density. Thereby, the to-be-processed water containing the sludge transferred to the carrier filtration tank E2 is filtered through the deposited filtration layer on which the carrier C2 is deposited, and is almost free of solids, so that the adjacent treated water tank T1. To be advected.
In the lower part of the carrier filtration tank E2, a backwash pipe D2 is provided as a backwashing device for the carrier C2, which diffuses air in order to remove sludge that causes clogging attached to the carrier C2. About the air diffusion pipe | tube D1 and the backwashing pipe | tube D2, it is preferable that the bubble supply amount can be adjusted.

  In the backwashing of the carrier C2 by the backwash tube D2, for example, a timer may be connected to the backwash tube D2, and the backwash tube D2 may be operated periodically to backwash the carrier C2. Further, the frequency of backwashing can be appropriately determined according to the season or the inflow load.

  Further, if the carrier C2 has a smooth surface, the sludge that causes clogging during backwashing can be easily peeled off, and the filtration area can be designed freely.

Further, the carrier filtration tank E2 has an air lift pump A2 as a transfer mechanism for transferring the water to be treated and sludge to the solid-liquid separation tank N1, and an air lift pump as a transfer mechanism for transferring the water to be processed and sludge to the carrier flow tank E1. A3 is provided.
The air lift pump A2 is configured to be able to circulate water to be treated and nitric acid containing nitric acid in the lower part of the carrier filtration tank E2 at a regular amount to the solid-liquid separation tank N1 during normal processing, and is transferred to the solid-liquid separation tank N1. Since the water to be treated is transferred from the solid-liquid separation tank N1 to the anaerobic filter bed tank N2 and denitrified, the nitrogen component can be removed, and further, the transferred sludge is used as excess sludge and the solid-liquid separation tank N1. And can be stored in an anaerobic filter bed tank N2.
On the other hand, the air lift pump A3 is configured to be able to transfer the water to be treated and the sludge flowing out from the carrier flow tank E1 and flowing into the carrier filtration tank E2 to the carrier flow tank E1. Since the transfer of sludge can prevent a decrease in the total amount of organisms in the carrier fluidized tank E1, the opportunity for contacting microorganisms and the water to be treated is increased, the treatment efficiency of BOD in the water to be treated is improved, and the high load treated water However, it can be decomposed efficiently. Furthermore, the nitrification reaction of the ammonia component in the water to be treated can be promoted. In addition, by preventing a decrease in the total amount of organisms in the carrier fluid tank E1, the decomposition efficiency of organic components and the like is increased, and the oxygen supply amount in the carrier filtration tank E2 is also increased, thereby improving the purification efficiency in the carrier filtration tank E2. be able to.

  It is possible to provide a control mechanism that controls the transfer of water to be treated and sludge of the air lift pump A2 and the air lift pump A3 according to the backwash timing. The control mechanism can be used as long as it is configured to control the air supply from the air supply device to the air lift pump A2 and the air lift pump A3 at the time of backwashing or immediately after backwashing.

  The treated water tank T1 is configured to be able to separate and prevent the separated sludge, and only the clean supernatant that has passed through the carrier filtration tank E2 can be transferred to the disinfection tank Q. The treated water that has flowed into the sterilization tank Q contacts the solid disinfectant and is sterilized, and then flows into the discharge pump tank S having the discharge pump P2. After the sterilized water to be treated is temporarily stored in the discharge pump tank S, it is discharged from the discharge port Z to the outside of the tank.

  In the septic tank described above, the water to be treated and sludge in the carrier filtration tank E2 are transferred to the carrier flow tank E1 for a predetermined time during backwashing or after backwashing to remove the sludge adhering to the carrier C2, and after the predetermined time has passed, the carrier filtration is performed. A method of transferring the treated water and sludge in the tank E2 to the solid-liquid separation tank N1, or vice versa, that is, the treated water and sludge in the carrier filtration tank E2 are transferred to the solid-liquid separation tank N1 for a predetermined time. After a lapse of time, by operating the method of transferring the water to be treated and sludge in the carrier filtration tank E2 to the carrier fluidization tank E1, it is possible to prevent a decrease in the total amount of organisms in the carrier fluidization tank E1, and to filter in the carrier filtration tank E2. The total amount of organisms reduced after the carrier backwashing can be recovered early.

  That is, during or after the backwashing of the carrier C2 in the carrier filtration tank E2, sludge separated from the carrier C2 floats in the carrier filtration tank E2, and gradually settles to the bottom. By starting the air supply to the air lift pump A3 at the time of backwashing or after backwashing, the sludge settled at the bottom can be transferred to the carrier fluid tank E1 together with the water to be treated, so that the total amount of organisms in the carrier fluid tank E1 is reduced. Can be prevented.

  A predetermined time for transferring the sludge to the carrier flow tank E1 is appropriately set, and after the set predetermined time has elapsed, the air supply to the air lift pump A3 is stopped and the air supply to the air lift pump A2 is started to settle to the bottom. The amount of sludge in the carrier fluidized tank E1 can be adjusted by performing a circulating operation in which the sludge is transferred to the solid-liquid separation tank N1 together with the water to be treated by the air lift pump A2, and the sludge transferred at this time is surplus It can be stored in the solid-liquid separation tank N1 as sludge.

Part of the sludge transferred to the carrier fluid tank E1 grows in the carrier fluid tank and is transferred to the carrier filter tank E2, thereby reducing the total amount of organisms reduced after the back filtration of the carrier in the carrier filter tank E2. Can be recovered. Therefore, it is possible to quickly prepare an environment in which biological filtration is performed by capturing SS (suspended material) in the deposited filtration layer, and the filtration capacity in the carrier filtration tank E2 can be improved on average.
The start and stop of the air supply of the air lift pump A2 and the air lift pump A3 can be controlled by a control mechanism.

  Furthermore, during or after backwashing to remove the sludge adhering to the carrier C2, the water to be treated and sludge in the carrier filtration tank E2 are transferred to the carrier flow tank E1 and the solid-liquid separation tank N1 at a predetermined rate. By doing so, it is possible to prevent a decrease in the total amount of organisms in the carrier fluidized tank E1, and to quickly recover the total amount of organisms that has decreased after backwashing of the filtration carrier in the carrier filtration tank E2.

  By operating by the method described above, biological treatment is stable, and even high load treated water can be treated efficiently. Furthermore, since the amount of sludge in the carrier fluidized tank E1 can be controlled by appropriately setting the sludge transfer rate of the airlift pump A2 and the airlift pump A3 for a predetermined time, a wide range of operation methods can be employed. .

The said transfer rate can be determined according to the inflow load of to-be-processed water.
At this time, when the inflow load is high, the ratio of transferring the sludge to the solid-liquid separation tank N1 by the air lift pump A2 is increased from the ratio of transferring the sludge to the carrier flow tank E1 by the air lift pump A3. The ratio of transferring the sludge to the carrier flow tank E1 by the air lift pump A3 is set to be larger than the ratio of transferring the sludge to the solid-liquid separation tank N1 by the air lift pump A2.

The septic tank is, for example, for 50 to 150 people and is a large-sized one corresponding to the amount of water of 2.55 to ³⁰ m ³ / day, and the solid-liquid separation tank N1 of the anaerobic treatment tank N is placed inside the first end plate B1. In contrast, as shown in FIGS. 2 to 4, the carrier flow tank E1 of the aerobic treatment tank is disposed inside the second end plate B2, and the solid-liquid separation tank N1 and the carrier flow tank E1 are arranged. Between, the carrier filtration tank E2, the treated water tank T1, the disinfection tank Q, and the discharge pump tank S are arranged.
Then, the carrier filtration tank E2 and the treatment water tank T1 are arranged in the radial direction of the septic tank body 1, and the disinfection tank Q and the discharge pump tank S are arranged in the longitudinal direction of the septic tank body 1 and arranged next to the radial direction of the treatment water tank T1. By installing, especially in the range of relatively small amounts of water such as 51 to 60 man tanks, the effect of compacting is large, and the amount of excavated soil during construction can be reduced.

The treated water is conveyed from the anaerobic filter bed tank N2 to the carrier flow tank E1 via the air lift pump A1 for flow rate adjustment, and the next carrier filtration tank E2 is overflowed from a position away from the treated water discharge part of the air lift pump A1. The treated water is flowing through. The air diffusion pipe D1 of the carrier flow tank E1 is pipe-shaped and disposed along the longitudinal direction of the septic tank body 1 at the center of the tank bottom, and the treated water in the tank is centered by the air diffusion of the air diffusion pipe D1. In, it becomes an upward flow, and near the surface, it becomes a circulating flow that flows toward the trunk side surface side.
The treated water discharge port of the air lift pump A1 and the overflow port to the carrier filtration tank E2 are respectively disposed on both sides of the air diffusion pipe D1. For this reason, the treated water flowing into the carrier fluidized tank E1 from the anaerobic filter bed tank N2 flows to the bottom along the trunk side part and circulates in the carrier fluidized tank E1, so that the opposite side across the air diffusion pipe D1 It is not a short-circuit flow to the overflow port to the carrier filtration tank E2 provided in, and is subjected to filtration after sufficiently aerobic treatment.

The treated water that has flowed into the carrier filtration tank E2 passes through the filling portion of the carrier C2 from the top to the bottom, and flows into the next treated water tank T1 from below.
As shown in FIGS. 3 to 4, the bottom openings of the carrier filtration tank E2 and the treated water tank T1 are divided into a partition wall between the carrier filtration tank E2 and the treated water tank T1, a treated water tank T1 disinfection tank Q, and a discharge pump tank S. And the partition wall is bent into the inside of the treatment water tank T1, and the precipitate in the treatment water tank T1 is promptly returned to the carrier filtration tank E2, thereby reducing the occurrence of scum in the treatment water tank T1. I am doing so.
Further, since the carrier filtration tank E2 and the treated water tank T1 are arranged side by side in the radial direction of the septic tank body 1, the bottom opening can be formed in a rectangular shape, and the treated water in the carrier filtration tank E2 does not drift. Since it flows into T1, the processing performance of the carrier filtration tank E2 can be stabilized.
From the treated water tank E2 to the disinfection tank Q, as shown in FIGS. 2 to 3 due to overflow from the upper part, it flows down through the disinfection cylinder 2, and further flows into the adjacent discharge pump tank S by overflow (FIG. 2, FIG. 4).

  Further, from the discharge pump tank S, treated water is pumped by the discharge pump P2, and discharged from the discharge port Z to the outside of the tank over the carrier flow tank E1.

  As shown in FIGS. 1 to 4, the inspection port H has a circular first inspection port H <b> 1 in the inflow portion of the raw water in order from the upstream side in a plan view so that all the tanks can be inspected and maintained. A circular second inspection port H2 is provided above the partition walls of the solid-liquid separation tank N1 and the anaerobic filter bed tank N2, a circular third inspection port H3 is provided at the center of the anaerobic filter bed tank N2, and the anaerobic filter bed tank N2 A rectangular fourth inspection port H4 on the rear end side above the air lift pump A1 is placed in a rectangular shape so that they can be inspected and maintained all over the carrier filtration tank E2, the treated water tank T1, the disinfection tank Q, and the discharge pump tank S. A large fifth inspection port H5 and a circular sixth inspection port H6 are provided above the air diffusion pipe D1 of the carrier flow tank E1.

[Another embodiment]
Other embodiments will be described below.

<1> An aerobic treatment tank different from the carrier flow tank E1 may be provided inside the first end plate instead of the anaerobic treatment tank N. In other words, the first aerobic treatment tank may be provided inside the first end plate, and the second aerobic treatment tank may be provided inside the second end plate, and in these cases, the tank disposed inside the first end plate may be A pretreatment tank is named generically.
<2> The aerobic treatment tank may be a tank in which an aeration apparatus is provided without providing a fluid carrier other than the formation in the carrier fluidized bed E1 in which the carrier C1 flows.
<3> The biofilm filtration tank may be a filtration tank provided with a fixed filter bed for supporting microorganisms in addition to the carrier filtration tank E2 provided with the carrier C2. That is, any tank capable of performing biological contact oxidation treatment and physical filtration may be used.
<4> In order to dispose the carrier filtration tank E2, the treated water tank T1, the disinfection tank Q, and the discharge pump tank S between the solid-liquid separation tank N1 and the carrier fluidization tank E1, the tank is used as a septic tank body. You may arrange in 1 longitudinal direction or radial direction. In addition, as shown in FIG. 5, the first pair of the carrier filtration tank E2 and the treated water tank T1 is arranged in the radial direction of the septic tank body 1 in a plan view, and the second pair of the disinfection tank Q and the discharge pump tank S You may arrange in the radial direction of the septic tank main body 1, and arrange those 1st sets and 2nd sets in the longitudinal direction of the septic tank main body 1. In this case, there is no hindrance in providing the inspection port H, which is advantageous when the tanks have a larger capacity. The air lift pump A1 from the anaerobic filter bed tank N2 to the carrier flow tank E1, and the discharge pump tank S In addition to the discharge pump P2 from the discharge port Z to the discharge port Z, an outlet pipe A4 with a slit for transferring the treated water from the carrier flow tank E1 to the carrier filtration tank E2 may be necessary.

  In addition, as mentioned above, although the code | symbol was written in order to make contrast with drawing convenient, this invention is not limited to the structure of an accompanying drawing by this entry. In addition, it goes without saying that the present invention can be carried out in various modes without departing from the gist of the present invention.

  The present invention can be used particularly advantageously for large septic tanks.

DESCRIPTION OF SYMBOLS 1 Septic tank body B1 1st end plate B2 2nd end plate N Anaerobic treatment tank T1 Treated water tank Q Disinfection tank S Discharge pump tank H Inspection port W1 Bulkhead (first bulkhead)
W2 partition (second partition)
W3 partition (third partition)

Claims (3)

The first end plate and the second end plate having curved surfaces protruding outward at both ends are provided in the septic tank body, and there is a water treatment space inside the septic tank body, and the water treatment space is an anaerobic treatment tank or in order of treatment. A pretreatment tank consisting of an aerobic treatment tank, an aerobic treatment tank, a biofilm filtration tank, a treatment water tank, a disinfection tank, and a discharge pump tank are separately formed through partition walls, and a plurality of them are disposed above these tanks. A septic tank provided with an inspection port,
The pretreatment tank is arranged inside the first end plate at one end in the water treatment space,
Arranging the aerobic treatment tank inside the second end plate at the other end,
A purification tank in which the biofilm filtration tank, the treated water tank, the disinfection tank, and the discharge pump tank are disposed between the pretreatment tank and the aerobic treatment tank.   The biofilm filtration tank and the treated water tank are arranged in the radial direction of the septic tank body, and the disinfection tank and the discharge pump tank are arranged in the longitudinal direction of the septic tank body, and are arranged beside the radial direction of the treated water tank. The septic tank according to claim 1.   The pretreatment tank is an anaerobic treatment tank, and is a partition partitioning in the longitudinal direction of the septic tank body in the partition wall, into the biofilm filtration tank, the treatment water tank, the disinfection tank, and the discharge pump tank. On the other hand, the septic tank according to claim 1 or 2, wherein the anaerobic treatment tank and the aerobic treatment tank are partitioned.

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