JP5001885B2 - Septic tank - Google Patents

Description

  The present invention relates to a septic tank in which a bowl-shaped cover member is installed on a partition wall that divides a tank body into a plurality of processing tanks.

In conventional septic tanks, through holes for inserting bolts are respectively provided on the left and right side edge portions of the bowl-shaped cover member and the partition wall on which the cover member is installed, and the cover member is disposed at a predetermined position on the partition wall. The through hole of the cover member is aligned with the through hole of the partition wall (hereinafter, this through hole provided on the partition wall side is referred to as a fixing portion), and bolts are inserted into the two through holes. And the septic tank which fixes a cover member to a partition wall by fastening with a nut etc. is known.
Such a prior art is widely known among those skilled in the art, and since there is no patent document or the like that is mentioned in detail, a prior art document cannot be disclosed.

However, in the conventional septic tank, in order to securely fix the cover member to the partition wall, it is common that fixing portions are provided at a plurality of positions above and below the partition wall (for example, the cover member is When fixing to the partition wall at the upper and lower portions of the left and right side edge portions, it is necessary to provide at least four fixing portions on the partition wall).
If the number of fixing parts is large, the work of inserting and fastening bolts increases, and there is a problem that it takes time and labor when fixing the cover member to the partition wall.
Further, the fixing unit may be provided at a position lower than the lowest water level of the treatment tank (if the treatment tank has the lowest water level, the water level to which the treated water can be transferred to the treatment tank other than the treatment tank). In this state, the fixing portion can be constantly submerged in the water to be treated, and the water to be treated has a high possibility of leaking from a gap generated in the fixing portion.
This invention is made | formed in view of the said situation, The objective is to provide the septic tank which the attachment operation | work of a cover member is simple, and can suppress the leakage of to-be-processed water.

In order to achieve the above object, the invention according to claim 1 of the present invention is a septic tank in which a bowl-shaped cover member is installed on a partition wall that divides the tank body into a plurality of processing tanks. In addition , ribs are continuously provided in the vertical direction at positions on the left and right outside of the wall surface of the partition wall where the cover member abuts, and the upper portion of the cover member is fixed at a fixing portion provided on the partition wall. The fixing portion is the minimum for the water to be treated in the treatment tank provided with the cover member to be transferred from the treatment tank provided with the cover member to another treatment tank on the downstream side and discharged to the outside from the purification tank. It is provided only at a position above the water level in the treatment tank provided with the cover member, the position of the lower part of the cover member is regulated by an interior member provided in the treatment tank, Separate Characterized in that so as to prevent the.

[Action and effect]
In the present invention, only the upper part of the bowl-shaped cover member is fixed to the partition wall at the fixed portion, and unlike the conventional septic tank, the fixed portion is provided at a plurality of locations above and below the partition wall. Therefore, the fixing work of the cover member to the partition wall can be simplified.
Furthermore, the fixed portion is at least a minimum for the water to be treated in the treatment tank provided with the cover member to be transferred from the treatment tank provided with the cover member to another treatment tank on the downstream side and discharged from the purification tank to the outside. Since it is provided only at a position above the water level in the treatment tank provided with the cover member, the possibility that the fixed part is always buried in the water to be treated is reduced, and the treatment from the gap generated in the fixed part is reduced. Water leakage can be suppressed.
The upper part of the cover member is fixed by the fixing part, and the position of the lower part of the cover member is regulated by the interior member provided in the treatment tank to prevent the separation from the partition wall. Similarly, the left and right side edge portions of the cover member can abut against the wall surface of the partition wall without a gap.

Further , according to the present invention, since the ribs are continuously provided in the vertical direction at the left and right outer positions where the cover member of the wall surface of the partition wall abuts, when the cover member is fixed to the partition wall, the cover Positioning of the left and right sides of the partition wall of the member is facilitated, and attachment workability is improved.
Further, rattling of the cover member in the left-right direction during operation of the septic tank can be prevented, and even if the partition wall is warped and a gap is formed between the cover member and the wall surface of the partition wall, the gap is a rib. Can be blocked. In addition, the cover member can be prevented from expanding and deforming due to the water pressure of the water to be treated, the fixing of the interior member, and the like.

In the invention according to claim 2 of the present invention, a flange portion that abuts against the wall surface of the partition wall at the left and right side edge portions of the cover member, the flange portion, and the rib A folded portion capable of surface contact is provided.
[Action and effect]
According to the present invention, the left and right side edge portions of the cover member are provided with a flange portion that comes into contact with the wall surface of the partition wall, and a folded portion that is connected to the flange portion and that can be brought into surface contact with the rib. ing. Therefore, the flange portion and the folded portion of the cover member come into contact with the wall surfaces and ribs of the partition wall, respectively, and the sealing performance of the left and right side edge portions of the cover member can be improved.

Embodiments of the present invention will be described below with reference to the drawings.
Embodiment
(Overall configuration of septic tank)
FIG. 1 schematically shows a side cross section of a septic tank 1 of the present invention that can purify domestic wastewater (sewage) as treated water. In addition, the solid line arrow in FIG. 1 has shown the advection direction of to-be-processed water, and the broken line arrow has shown the return direction of the solid content (sludge etc.) collected in the tank bottom part.
FIG. 2 is a longitudinal sectional view taken along line II-II in FIG.
FIG. 3 is a cross-sectional view of the septic tank 1 near the anaerobic treatment tank A2.

  As shown in FIG. 1, the septic tank 1 includes an anaerobic tank A for partitioning the tank body 2 having a manhole M and the like with a second partition wall 4 and a third partition wall 5 and anaerobically treating the water to be treated. The aerobic tank B for aerobically treating the water to be treated anaerobically in the anaerobic tank A and the precipitation tank C for precipitating the treated water aerobically treated in the aerobic tank B Disinfection tank D for disinfecting by flowing in the treated water by overflow is provided, and the treated water in which the solid content is precipitated in the sedimentation tank C is discharged from the outflow pipe 6 serving as an outlet through the disinfection tank D. Can be discharged.

  The anaerobic tank A is firstly divided into a solid-liquid separation tank A1 into which the water to be treated flows from the outside through the inflow pipe 7 and an anaerobic treatment tank A2 for anaerobically treating the water to be treated solid-liquid separated in the solid-liquid separation tank A1. Water to be treated, which is partitioned by the partition wall 3 and separated in the solid-liquid separation tank A1, is transferred to the anaerobic treatment tank A2 from the two advection ports 9 provided in the first partition wall 3, and then the anaerobic treatment tank The water to be treated that has been anaerobically treated in A2 is configured to flow into the aerobic tank B by overflow from the inlet 8 provided in the third partition wall 5.

  In the solid-liquid separation tank A 1, the first baffle 10 having a substantially U-shaped horizontal cross section is fixed to the tank wall so as to surround the outlet side of the inflow pipe 7 at the upper end portion, and the solid liquid is separated through the inflow pipe 7. The flow direction of the water to be treated flowing into the liquid separation tank A1 is regulated downward.

  As shown in FIG. 2, each of the advection ports 9 is formed in a semicircular shape in which the straight line portion extends along the vertical direction and the arc portion is disposed on the tank center side, as shown in FIG. As shown in FIG. 3, the inflow path to each advection port 9 of the to-be-processed water in the solid-liquid separation tank A1 is arranged in the horizontal direction at the middle height position substantially at the center of the first partition wall 3. A guide member 11 that extends along the wall surface 3 b of the one partition wall 3 is provided for each advection port 9.

  As shown in FIG. 3, the guide member 11 is formed in a half split shape that covers the advection port 9 from the center in the left-right direction of the first partition wall 3, and is substantially along the wall surface 3 b of the first partition wall 3. After providing the opening 12 that opens in the horizontal direction toward the tank wall 24 side, the water to be treated in the solid-liquid separation tank A1 flows into the opening 12 along the first partition wall 3 from the tank wall 24 side, The guide member 11 is guided along the inner peripheral surface and flows into the advection port 9.

In the anaerobic treatment tank A2, the soluble organic substance contained in the water to be treated can be decomposed by anaerobic microorganisms adhering to the filter medium 26 of the anaerobic filter bed 13 (interior member).
The anaerobic filter bed 13 includes an installation base 23 having a filter medium installation part 23a and leg parts 23b that are framed in a lattice pattern, a filter medium 26 that adheres and inhabits anaerobic microorganisms, and a filter medium presser member 27 that is framed in a grid pattern. It is prepared for.

  In the anaerobic filter bed 13, the filter medium pressing member 27 is provided so as to press the filter medium 26 placed on the filter medium installation portion 23 a of the installation table 23 from above, as shown in FIGS. 1 to 3. In addition, an end portion of the filter medium pressing member 27 is arranged on the wall surface 5a on the anaerobic treatment tank A2 side of the third partition wall 5 so that the filter medium pressing member 27 does not move upward, and the first The partition wall 3 is locked by a locking portion 28b disposed on the wall surface 3a on the anaerobic treatment tank A2 side.

Further, a bowl-shaped cover member 14 is fixed to the wall surface 3a of the first partition wall 3 on the anaerobic treatment tank A2 side. The cover member 14 surrounds the left and right advection ports 9 in a series over the left and right sides, and forms a flow path 20 that guides the water to be treated that has flowed from the advection port 9 to the anaerobic filter bed 13.
Moreover, the cover member 14 is extended to a position higher than the water level of the water to be treated in the anaerobic treatment tank A2, and the water to be treated that has passed through the lower end side of the cover member 14 flows into the anaerobic filter bed 13. After the anaerobic treatment, it is configured to flow into the aerobic tank B by overflow from the inlet 8 provided in the third partition wall 5.

  As shown in FIG. 1, the aerobic tank B is filled with a large number of resin carriers 15 whose outline shape is substantially spherical in a flowable manner, and provided with an aeration pipe 16 for aeration. The carrier 15 is aerated while being agitated with the blown air, whereby the biological film adhering to the surface of the carrier 15 and the water to be treated are repeatedly brought into contact with each other to decompose and remove organic substances in the water to be treated. It is composed of a carrier fluid tank that oxidizes nitrogen compounds, and a porous plate 17 for preventing carrier outflow is provided at the top of the tank.

  And the lower end side of the 2nd partition wall 4 is bent to the sedimentation tank C side, and the to-be-treated water which carried out the aerobic treatment is settling tank C from the outflow port 18 between the lower end of the 2nd partition wall 4 and a tank bottom face. And a return device 19 for returning the solid content (sludge and the like) accumulated at the bottom of the tank to the anaerobic tank A.

  The return device 19 communicates and connects an air lift pump type suction pipe 21 to the return pipe 22 and opens the suction port near the bottom of the tank. It is comprised so that it can return to the anaerobic tank A from the inner side of the 1st baffle 10 of the separation tank A1.

The disinfecting tank D includes an overflow weir 60 at the inlet of the water to be treated from the settling tank C, and is configured to flow in from the overflow weir 60 to which the solid content is precipitated in the precipitation tank C by overflow. Has been.
In the septic tank 1 shown in FIG. 1, the water to be treated that has flowed from the inflow pipe 7 passes through the solid-liquid separation tank A1, the anaerobic treatment tank A2, the aerobic tank B, the precipitation tank C, and the disinfection tank D. The overflow weir 60 is configured at a position where the lower end of the overflow weir 60 is higher than the lower end of the inlet 8 which is the overflow port from the anaerobic treatment tank A2 to the aerobic tank B.
For this reason, when the to-be-processed water does not flow into the septic tank 1 and the to-be-processed water does not exceed the overflow weir 60, the water level of the septic tank 1 becomes the lowest. That is, the minimum water level (LWL) of each treatment tank is defined by the height of the lower end of the overflow weir 60 (advection part).

(Configuration of anaerobic treatment tank A2)
Next, the configuration of the anaerobic treatment tank A2 will be described in detail below together with the method for assembling the cover member 14 and the anaerobic filter bed 13 in the anaerobic treatment tank A2.
FIG. 4 is a perspective view showing a state in which the anaerobic filter bed 13 (interior member) is installed after fixing the cover member 14 to the first partition wall 3.
FIG. 5 is a longitudinal sectional view showing a state in which the engaging member 37 of the cover member 14 is engaged with the through hole 33 of the first partition wall 3.
FIG. 6 is an enlarged view of the engaging member 37 in the cover member 14.

As shown in FIGS. 2 and 4, two first ribs 30 and two second ribs 31 are provided on each side of the wall 3 a on the anaerobic treatment tank A <b> 2 side of the first partition wall 3 on both sides of the advection port 9. It is provided continuously in the vertical direction.
Further, as shown in FIGS. 1 and 4, a groove 32 extending in the vertical direction is formed by the first rib 30 and the second rib 31, and each groove 32 has a minimum water level (LWL) of the anaerobic treatment tank A2. ) Are provided at positions above the lower end of the overflow weir 60 (advection part), and each convex part 42 has a circular through hole 33 (leading to the solid-liquid separation tank A1). (Fixed part) is formed.

As shown in FIG. 4, the cover member 14 has a semi-cylindrical shape having a substantially U-shaped horizontal cross-sectional shape (saddle shape), and a plurality of reinforcing protrusions are spaced vertically on the outer peripheral surface thereof. A portion 34 is provided.
A flange portion 35 is provided on each of the left and right side edge portions of the cover member 14, and a folded portion 36 is continuously provided on the flange portion 35 in a direction perpendicular to the plate surface of the flange portion 35. Yes.

In addition, at the upper part of the left and right side edge portions of the cover member 14, an accommodation recess 38 for accommodating and protecting the engagement member 37 is provided.
As shown in FIG. 6, each engagement member 37 includes a shaft portion 39 and a tip head portion 40 that protrude from the through hole 33, and a pair of engagement pieces 41 are provided on the tip head portion 40. The pair of engagement pieces 41 are in a posture that is widened in a C shape toward the upper side in the insertion direction so that the rear end portions are spaced apart from each other in the insertion direction with respect to the through hole 33. It is provided at the tip head 40.

In order to fix the cover member 14 to the first partition wall 3, first, as shown in FIG. 5A, the engagement members 37 of the cover member 14 and the through holes 33 of the first partition wall 3 are connected. Perform alignment.
Then, as shown in FIG. 5 (b), as shown in FIG. 4, while the distal end heads 40 of the respective engaging members 37 of the cover member 14 are pushed into the corresponding through holes 33 of the first partition walls 3, respectively. The left and right side edge portions of the cover member 14 are fitted into the respective grooves 32 of the first partition wall 3.

At this time, the two first ribs 30 (the two first ribs 30 are respectively provided at the left and right outer positions where the cover member 14 of the wall surface 3a of the first partition wall 3 abuts). Positioning on the left and right sides of the partition wall is facilitated, and mounting workability is improved.
Further, the action of the two first ribs 30 can prevent the cover member 14 from rattling in the left-right direction during the operation of the septic tank, and the first partition wall 3 is warped to cover the cover member 14 and the first partition. Even if a gap is generated between the wall 3 and the wall surface 3 a, the gap can be blocked by the first rib 30. In addition, the cover member 14 can be prevented from expanding and deforming due to the water pressure of the water to be treated and the fixing of the interior member.

  As shown in FIG. 3, the flange portions 35 at the left and right side edge portions of the cover member 14 abut on the bottom surface of the groove 32 (the wall surface 3 a on the anaerobic treatment tank A <b> 2 side of the first partition wall 3), and the flange portion. The folded-back portion 36 provided continuously to the surface 35 is configured to be in surface contact with the first rib 30, and the sealing performance of the left and right side edge portions of the cover member 14 can be improved.

As shown in FIGS. 5 and 6, in each engagement member 37 of the cover member 14, the front end portions 40 having a diameter smaller than that of the through hole 33 are pushed into the through hole 33 in the front view so The engaging pieces 41 are forcibly elastically deformed so as to be close to each other, and the engaging pieces 41 that have come out of the through-holes 33 are engaged with the outer peripheral portion of the through-holes 33 in a retaining state by the return deformation. While being accommodated inside the portion 42, the convex portion 42 is configured to be fitted into the accommodating concave portion 38 of the cover member 14.
Therefore, as shown in FIG. 4, in the septic tank 1 of the present invention, the two engaging members 37 provided on the upper part of the cover member 14 are provided with two through-holes 33 (fixed portions) provided in the first partition wall 3. The cover member 14 is fixed to the first partition wall 3 by being inserted through the first partition wall 3. Unlike the conventional septic tank, the cover member 14 is fixed to the upper and lower portions of the first partition wall 3. The number can be reduced, and the fixing operation of the cover member 14 to the partition wall can be simplified.

  Furthermore, since the through hole 33 (fixed part) is provided at a position above the lower end of the overflow weir 60 (advection part) that defines the lowest water level (LWL) of the anaerobic treatment tank A2 provided with the cover member, the through hole The possibility that 33 (fixed portion) is always buried in the treated water is reduced, and leakage of the treated water from the gap generated in the through hole 33 (fixed portion) can be suppressed. Further, since the through hole 33 (fixing portion) for fixing the cover member below the lowest water level is not provided, there is no possibility of deterioration in processing performance due to leakage of water to be processed outside the tank.

Next, a procedure for installing the anaerobic filter bed 13 (interior member) in the anaerobic treatment tank A2 will be described.
As shown in FIG.1 and FIG.4, first, the installation base 23 is put into the anaerobic treatment tank A2 with its legs 23b facing down, and installed on the bottom surface of the anaerobic treatment tank A2.
An installation recess 43 is formed in the filter medium installation portion 23 a of the installation table 23. When the installation table 23 is installed in the anaerobic treatment tank A 2, the installation recess 43 of the filter medium installation unit 23 a is formed at the lower end of the cover member 14. The outer peripheral part other than the installation recess 43 of the filter medium installation part 23a can be fitted so as to surround the outer periphery, and the first partition wall 3, the inner wall 44 (see FIG. 3) of the anaerobic treatment tank A2, and the third partition wall 5 It is comprised so that it may contact | abut. As a result, as shown in FIG. 1, the position of the lower portion of the cover member 14 is restricted by the installation base 23, and is prevented from being separated from the partition wall 3.

  At this time, the fitting position of the filter medium installation part 23a and the cover member 14 is such that no excessive force is applied to the cover member 14 even if the filter medium installation part 23a is deformed, that is, the surface of the cover member 14 is the filter medium installation. As long as the deformation direction of the portion 23a is assumed (the filter material installation portion 23a is deformed in the vertical direction due to floating of the filter material or adhesion of a biofilm), the surface has a surface parallel to the deformation direction of the filter material installation portion 23a. The position is a position (a position having a vertical surface in a range in which deformation is assumed in this embodiment).

Next, as shown in FIGS. 1 and 4, a filter medium 26 that can inhabit anaerobic microorganisms is placed on the filter medium installation part 23 a of the installation table 23, and then the filter medium 26 is pressed from above. The filter medium pressing member 27 is placed on the filter medium 26, and the end of the filter medium pressing member 27 is disposed on the wall surface 5a of the third partition wall 5 on the anaerobic treatment tank A2 side. The partition wall 3 is locked by a locking portion 28b disposed on the wall surface 3a on the anaerobic treatment tank A2 side (see FIGS. 1 to 3).
As shown in FIGS. 3 and 4, the filter material pressing member 27 is formed with a pressing recess 45, and when the end of the filter material pressing member 27 is locked by the locking portions 28 a and 28 b, The presser concave portion 45 of the filter medium pressing member 27 can be fitted so as to surround the outer periphery of the reinforcing convex portion 34 of the cover member 14, and the outer peripheral portion other than the presser concave portion 45 of the filter medium presser member 27 is connected to the first partition wall 3, It is comprised so that the inner wall 44 of the anaerobic processing tank A2 and the 3rd partition wall 5 may be contact | abutted.

[Another embodiment]
The lid-shaped cover member 14 in the present invention is not limited to the one that forms the flow path of the water to be treated as in the above-described embodiment, but as shown in FIGS. It may be used as a cover, or may form an insertion passage 50 for inserting a vacuum hose 49 for cleaning, or may be used as a scum baffle although not shown.
In addition, the advection portion in the present invention is not limited to the overflow port through which the water to be treated overflows as in the above-described embodiment, but as shown in FIGS. 7 and 8 to be described later, the suction port 48 of the air lift pump 47 (this In this case, the lowest water level (LWL) corresponds to the installation height of the suction port 48).

As shown in FIGS. 7 and 8, in the septic tank of another embodiment, the solid-liquid separation tank A <b> 1 is provided with an air lift pump 47 having a U-shaped tube, and the water to be treated is sucked from the suction port 48. It is configured to be transferred to the anaerobic treatment tank A2. In this case, the water level that cannot be transferred by the air lift pump 47 provided in the solid-liquid separation tank A1 is the lowest water level. That is, the suction port 48 of the air lift pump 47 serves as a convection section that defines the lowest water level (LWL) of the solid-liquid separation tank A1.
The cover member 14a functions as a cover for facilitating insertion / removal of the air lift pump 47 at the time of maintenance, and the upper part of the cover member 14a is provided at a position higher than the suction port 48 at the first partition wall 3. Is fixed to the wall surface 3b, and the position of the lower part is restricted by the interior member N1.

The cover member 14b forms a flow path 51 that guides the water to be treated treated in the anaerobic treatment tank A2 from the inflow port 8 provided in the third partition wall 5 to the aerobic tank B by overflow. The fixing portion 33b provided at a position above the inflow port 8 is fixed to the wall surface 5a of the third partition wall 5, and the lower portion is regulated by the interior member N2.
In this embodiment, the to-be-processed water which flowed into the anaerobic processing tank A2 is naturally advected to the downstream processing tank and discharged. That is, it is naturally discharged from the inflow pipe 6 through the aerobic tank B, the sedimentation tank C, and the disinfection tank D. For this reason, the minimum water level (LWL) of the aerobic tank B and the sedimentation tank C is defined by the lower end of the overflow weir 60 provided in the disinfection tank D, but the lower end of the inlet 8 is lower than the lower end of the overflow weir 60. Since it is comprised in a high position, the lower end of the inflow port 8 becomes an advection part that defines the lowest water level (LWL) of the anaerobic treatment tank A2.

The cover member 14c forms an insertion passage 50 for inserting a vacuum hose 49 for cleaning, and the upper part thereof is the lower end of the overflow weir 60 provided in the disinfection tank D (the lowest water level of the aerobic tank B ( The wall surface 4a of the second partition wall 4 is fixed at a fixed portion 33c provided at a position higher than the advection portion) that defines LWL), and the lower portion is regulated by the interior member N3.
In the septic tank of the present invention, the interior member for regulating the position of the cover member may be constituted by an air diffuser, a sludge return device, or the like fixed to the interior member other than the tank body, the partition wall, or the cover member.

The figure which showed typically the side cross section of the septic tank of this invention Longitudinal sectional view taken along line II-II in FIG. Cross-sectional view near the anaerobic treatment tank in the septic tank of the present invention The perspective view which showed a mode that the anaerobic filter bed (interior member) was installed after attaching a cover member to a 1st partition wall. The longitudinal cross-sectional view which showed a mode that the engagement member of a cover member and the through-hole of a 1st partition wall were engaged. Enlarged view of the engaging member in the cover member The figure which showed typically the side cross section of the septic tank of another embodiment The figure which showed the cross section of the septic tank of another embodiment typically

DESCRIPTION OF SYMBOLS 1 Septic tank 2 Tank main body 3 1st partition wall 3a Wall surface 4 2nd partition wall 5 3rd partition wall 5a Wall surface 6 Outflow pipe 7 Inflow pipe 8 Inlet 9 Transfer port 10 1st baffle 11 Guide member 12 Opening part 13 Anaerobic filter Floor (interior material)
14 Cover member 15 Resin carrier 16 Aeration diffuser tube 17 Perforated plate 18 Outlet 19 Return device 20 Flow path 21 Suction tube 22 Return tube 23 Installation base 23a Filter material installation part 23b Leg part 24 Tank wall 26 Filter medium 27 Filter material holding member 28 Locking portion 30 First rib 31 Second rib 32 Groove 33 Through hole (fixed portion)
34 Reinforcement convex part 35 Flange part 36 Folding part 37 Engaging member 38 Housing concave part 39 Shaft part 40 Tip head part 41 Engagement piece 42 Convex part 43 Installation concave part 44 Inner wall 45 of anaerobic treatment tank 47 Pressing concave part 47 Air lift pump 48 Inlet 49 Vacuum hose 50 Insertion passage 51 Channel 60 Overflow weir

Claims (2)

A septic tank in which a bowl-shaped cover member is installed on a partition wall that divides the tank body into a plurality of processing tanks,
Ribs are continuously provided in the vertical direction at positions on the left and right outer sides where the cover member of the wall surface of the partition wall abuts,
The upper part of the cover member is fixed at a fixing part provided on the partition wall, and the fixing part is disposed on the downstream side of the water to be treated in the treatment tank provided with the cover member from the treatment tank provided with the cover member. It is provided only at a position above the water level in the treatment tank provided with the cover member, which is at least necessary to be transferred to another treatment tank and discharged from the septic tank to the outside. A septic tank, the position of which is regulated by an interior member provided in the treatment tank, so as to prevent separation from the partition wall. The flange part which contact | abuts the wall surface of the said partition wall at the side edge part of the right and left of the said cover member, The folding | returning part connected with the flange part and the surface contact | abutting with the said rib is provided. 1. The septic tank according to 1 .

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