JP3300123B2 - Septic tank - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an anaerobic filter
The present invention relates to a septic tank provided with an aerobic filter bed first chamber, a second chamber, and a sedimentation tank in this order.

[0002]

2. Description of the Related Art Conventionally, in this type of septic tank, in both the first chamber and the second chamber of the aerobic filter tank, a filter medium assembled in a honeycomb shape or a randomly-filled filter medium is immersed and juxtaposed. Was. Also, in such a septic tank, the first chamber of the aerobic filter bed tank,
A treated water return path for individually returning treated water from the second aerobic filter tank to the anaerobic treatment tank is provided, and the liquid to be treated in the first aerobic filter tank is also the aerobic filter tank. Similarly, there was a septic tank having a structure in which the water to be treated in the second chamber was directly returned to the anaerobic filter bed tank.

[0003]

If domestic wastewater or the like is supplied as water to be treated to the above-mentioned conventional septic tank, the water to be treated is subjected to anaerobic biological treatment in a anaerobic filter bed tank. (Hereinafter abbreviated as anaerobic treatment)
Furthermore, nitrogen-containing components such as ammonia generated in the water to be treated by the decomposition flow into an aerobic treatment tank and are converted into nitrate nitrogen by aerobic biological treatment (hereinafter abbreviated as aerobic treatment) (hereinafter referred to as nitrate nitrogen). , Nitrification), and the nitrified water to be treated (hereinafter, referred to as nitrification liquid) is returned to an anaerobic filter bed tank to be converted into nitrogen gas by anaerobic treatment (hereinafter, abbreviated as denitrification), gas After being removed as wastewater, the wastewater is flown downstream as treated water and discharged from the sedimentation tank. In addition, when biological treatment is performed on water to be treated such as domestic wastewater, separated sludge (hereinafter simply referred to as separated sludge) such as suspended matter of sludge separated from the filter medium of each filter bed is generated, which hinders aerobic treatment. However, since the above-mentioned conventional septic tank can return the separated sludge to the anaerobic filter bed tank together with the return of the treated water, the separated sludge is returned to the anaerobic filter bed tank, and the aerobic filter bed tank is returned. This is intended to reduce the processing load of.

[0004] However, while the nitrification solution is denitrified in the anaerobic filter bed and the separated sludge is returned to the anaerobic filter tank, the aerobic treatment can be effectively performed. 2
Since the liquid to be treated in which the amount of dissolved oxygen in the chamber is excessive flows into the anaerobic filter tank, the amount of dissolved oxygen in the anaerobic filter tank tends to increase, and the anaerobic treatment activity of the anaerobic filter tank increases. There was a drawback of lowering. In addition, since the amount of water flowing into the anaerobic filter bed tank increases due to the return of the water to be treated from the first and second chambers of the aerobic filter bed tank, the separated sludge generated from the anaerobic filter bed tank is removed by the aerobic filter bed tank. It becomes easy to flow into the filter bed tank 1 chamber, so that the BOD in the aerobic filter bed tank 1 chamber increases, and the treatment load of the water to be treated in the aerobic filter bed tank 1 chamber increases. At the same time, the amount of the separated sludge and the water to be treated having a high BOD (high treatment load) are likely to flow into the aerobic filter bed tank 2nd chamber. The ratio of the exfoliated sludge increases, and the nitrification capacity in the second chamber of the aerobic filter bed tank tends to decrease.

Further, although the separated sludge flowing into the second chamber of the aerobic filter tank is settled in the settling tank and is not discharged out of the septic tank, a large amount of separated sludge is accumulated in the settling tank. When a large amount of water to be treated is supplied to the septic tank at one time, there is a possibility that treated water that has not been sufficiently purified flows out of the septic tank, such as separation sludge flowing out of the septic tank.

Accordingly, an object of the present invention is to provide
An object of the present invention is to provide a purification tank in which a denitrification treatment is efficiently performed without increasing a processing load in the aerobic filter tank, and the activity of the anaerobic filter tank does not decrease.

[0007]

To achieve this object, a feature of the present invention is that a filter medium is provided in the second chamber of the aerobic filter bed tank over the entire flow path, and the aerobic filter is provided. A first return path for returning the water to be treated from the first bed tank to the anaerobic filter bed tank, and returning the water to be treated from the second chamber of the aerobic filter tank to the first chamber of the aerobic filter tank. It is more preferable that the filter medium is a biological filter medium having a porosity of 70% or less, and the operation and effect are as follows.

[0008]

In other words, by providing a second return path for the liquid to be treated from the second chamber of the aerobic filter tank to the first chamber of the aerobic filter tank, the separated sludge of the second chamber of the aerobic filter tank is provided. The liquid to be treated, including the nitrifying solution and the nitrifying liquid, is returned to the first chamber of the aerobic filter tank,
The liquid to be treated in the chamber is returned to the anaerobic filter bed tank through the first return path. Therefore, without increasing the amount of water to be treated flowing from the anaerobic filter tank to the first chamber of the aerobic filter tank, the second aerobic filter tank can be used.
The separated sludge and nitrification liquid in the chamber can be returned to the anaerobic filter bed tank, and the separated sludge hardly accumulates in the aerobic filter bed tank 2 and the liquid to be treated to the anaerobic filter bed tank is reduced. As the amount of water returned decreases, the amount of water to be treated flowing from the anaerobic filter tank to the first chamber of the aerobic filter tank decreases, so that the flow of exfoliated sludge into the first chamber of the aerobic filter tank is suppressed. With the decrease in the amount of the separated sludge in the first aerobic filter tank, the flow of the separated sludge into the second aerobic filter tank is suppressed. Thereby, the aerobic filter bed tank 2
The processing load of the room is reduced, and the first room of aerobic filter bed tank,
The nitrification liquid between the second chambers is favorably returned to the anaerobic filter bed tank, and denitrification is favorably performed in the anaerobic filter bed tank.

By the way, in the second chamber of the aerobic filter tank, the BOD decreases due to the decrease in the amount of stripped sludge.
The concentration of dissolved oxygen increases, and the concentration of dissolved oxygen also tends to increase in the liquid to be treated. However, even if the liquid to be treated is returned to the anaerobic filter tank, the liquid to be treated is once aerobic. After returning to the filter bed tank 1 chamber and returning to the anaerobic filter bed tank, the amount of exfoliated sludge is larger in the aerobic filter tank tank 1 than in the aerobic filter bed tank 2 and the BOD is also higher. Since it is high, the dissolved oxygen concentration is also lower than that of the aerobic filter tank 2 so that the dissolved oxygen concentration of the liquid to be treated returned to the anaerobic filter tank is not so high. A decrease in the activity of the tank against anaerobic treatment can be prevented.

[0010] Here, since the filter medium is provided in the second chamber of the aerobic filter bed tank over the entire flow path, the separated sludge hardly accumulates in the sedimentation tank, and the liquid to be treated having a small processing load is removed. Since it only needs to be treated, more advanced water purification can be performed.

[0011] If the filter medium is a biological filter medium having a porosity of 70% or less, its function can be sufficiently exhibited by suppressing the amount of the inflowing sludge, so that more advanced water purification can be performed. .

[0012]

Therefore, according to the septic tank of the present invention, the denitrification treatment of the liquid to be treated can be performed satisfactorily and the processing load on the second aerobic filter bed tank can be reduced. The quality of the treated liquid flowing out can be improved, and a septic tank useful for environmental preservation can be provided.

[0013] Further, since the sludge in the second chamber of the aerobic filter tank can be reduced, the visibility of the aerobic filter tank is improved and the second chamber of the aerobic filter tank can be easily inspected. Become. In addition, since the inspection becomes easy, a septic tank that can be easily maintained and managed can be provided. In addition, it can be easily inspected, the nitrification capacity of the aerobic filter bed tank can be promoted, and the sedimentation of the separated sludge does not easily occur in the sedimentation tank. I can do it.

Further, since the sludge is hardly settled in the settling tank, the separated sludge can be separated from the liquid to be treated without using a conventional large settling tank. And the whole septic tank is downsized,
It can be installed in a small space.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, from the upstream side, the first anaerobic filter tank
The anaerobic filter tank N composed of the chamber N1 and the anaerobic filter tank second chamber N2, the aerobic filter bed tank E composed of the first aerobic filter tank E1 and the second chamber E2, the sedimentation tank P, and the disinfection tank Q The purification tank is provided so that the liquid to be treated flows in this order by natural advection.

In the anaerobic filter bed tank N, anaerobic microorganisms for anaerobic treatment of the liquid to be treated and denitrification of nitrate nitrogen are grown, and a filter medium F is used as a filter bed F for fixing the biofilm.
1 is provided in the first anaerobic filter tank N1 and the filter medium F2 is provided in the second anaerobic filter tank N2.

The aerobic filter bed tank E is provided with an aerobic filter medium C1 as a filter bed C for fixing aerobic microorganisms which decompose the remaining organic substances in the liquid to be treated and nitrify ammoniacal nitrogen. The filter medium C2 is placed in the first chamber E1 of the bed tank and the second chamber E of the aerobic bed tank
2 respectively. The filter medium C1 is in the form of a honeycomb net and has a first aerobic filter bed tank E so as to easily obtain a circulation flow in the tank.
The filter medium C2 is a biological filter medium having a porosity of 70%, and is disposed over the entire area of the flow path of the second chamber of the aerobic filter tank.

In the first chamber E1 of the aerobic filter bed, a circulating flow of the liquid to be treated is generated, so that the liquid to be treated containing organic matter is brought into good contact with the aerobic microorganisms fixed on the filter medium C1, and An air diffuser D for supplying air for giving necessary oxygen to the aerial microorganisms is provided below the filter medium C1.

In the second chamber E2 of the aerobic filter bed, the filter medium C
An air supply pipe G for supplying oxygen to the filter medium 2 is provided below the filter medium C2 so that air can be supplied so as not to hinder the advection of the liquid to be treated. As a result, the gas passes through the filter medium C2 supplied with oxygen from the bubbles rising upward from below,
The liquid to be treated flows downward from above the filter medium C2 in opposition to the air bubbles so that biological filtration can be performed.

Further, in order to prevent clogging due to excessive attachment of a biological film or the like to the filter medium C1,
A backwash tube R is provided below the filter medium C1 for releasing bubbles and causing collision with the wastewater, and peeling off excess biofilm and the like as peeled sludge.

[0021] The first chamber E1 of the aerobic filter bed tank by the separated sludge.
The first return path A1 for returning the liquid to be treated containing the exfoliated sludge and the nitrification liquid to the first chamber N1 of the anaerobic filter bed tank in order to prevent the BOD in the tank from increasing too much and to denitrify the nitrification liquid. A lift pipe A11 and a return pipe A12 communicating with the upper part of the air lift pipe A11 and guiding the liquid to be treated to the anaerobic filter bed tank N are provided.

Further, the liquid to be treated containing the stripped sludge and the nitrifying solution is aerobically added to the second chamber E2 of the aerobic filter bed so that the separated sludge does not increase and the BOD does not increase too much, and the nitrifying solution is denitrified. The second return path A2 for returning to the first filter bed tank E1 is connected to the air lift pipe A21 and the upper part of the air lift pipe A21, and the liquid to be treated is returned to the first aerobic filter bed tank E1. And a tube A22.

Accordingly, the raw water to be treated which has flowed in from the inlet I is subjected to anaerobic treatment through the first and second chambers N1 and N2 of the anaerobic filter tank and is decomposed. Furthermore, it undergoes aerobic treatment and is further nitrified and decomposed. In the first chamber E1 of the aerobic filter tank, exfoliated sludge is generated by a circulating flow generated by aeration or an action of backwashing. The stripped sludge and the nitrified liquid to be treated are returned to the anaerobic filter bed tank N by the first return path A1, where they are decomposed and denitrified. On the other hand, the liquid to be treated, which has been treated in the first aerobic filter tank first chamber E1, flows into the second aerobic filter tank second chamber E2 due to overflow, but also in the second aerobic filter tank second chamber E2. By the treatment, nitrification and decomposition further progress. By the way, in the aerobic filter bed tank second chamber E2, the nitrifying liquid and the exfoliated sludge are returned to the aerobic filter bed tank first chamber E1 by the second return path A2. The decomposition of the sludge is performed in the first aerobic filter tank E1 and the anaerobic filter tank N to be returned, so that appropriate treatment is performed and the treatment in the second aerobic filter tank E2. The burden will be reduced.

The liquid to be treated in the second aerobic filter tank second chamber E2 is transferred from the bottom of the second aerobic filter tank second chamber E2 to the sedimentation tank P, where the separated sludge is settled and removed. Each tank is formed so that it overflows from the upper part of the container and is guided to the disinfecting tank Q, where it contacts the solid disinfectant and is disinfected, and then is discharged from the discharge port Z to the outside as a treated liquid. is there.

Therefore, the undiluted solution coming in from the inlet I is discharged after the above-mentioned treatment, so that it can be drained as highly purified treated water.

In the figure, H is a manhole used for checking the inside of the septic tank.

[0027]

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view of a septic tank according to the present invention.

[Explanation of symbols]

 N Anaerobic filter bed tank E1 Aerobic filter bed tank first chamber E2 Aerobic filter bed tank second chamber P Sedimentation tank C2 Filter media A1 First return path A2 Second return path

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuyuki Honda, 2nd Takamatsu, Kosai-cho, Koga-gun, Shiga Prefecture Inside of Kubota Shiga Plant (72) Inventor Masaharu Iwahashi 2nd Takamatsu, Kosai-cho, Koga-gun, Shiga 1 Kubota Corporation Shiga Plant (56) References JP-A-6-63574 (JP, A) JP-A-6-71281 (JP, A) JP-A-6-79293 (JP, A) −137799 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) C02F 3/00, 3/30

Claims (2)

(57) [Claims] 1. A purification tank provided with a first aerobic filter tank (E1), a second chamber (E2), and a sedimentation tank (P) in this order downstream of an anaerobic filter tank (N). The aerobic filter bed tank second chamber (E2) is provided with a filter medium (C2) covering the entire flow path, and the aerobic filter bed tank first chamber (E1) is provided with the anaerobic filter tank ( N) to the first return path (A) for returning the water to be treated.
1) and a purification tank provided with a second return path (A2) for returning treated water from the aerobic filter bed tank second chamber (E2) to the aerobic filter bed tank first chamber (E1). 2. The septic tank according to claim 1, wherein the filter medium (C2) is a biological filter medium having a porosity of 70% or less.