JP3167530B2 - Septic tank - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a purification tank provided with a primary treatment tank and an activated sludge treatment tank in this order from the inlet side of raw water to be treated.

[0002]

2. Description of the Related Art Generally, in this type of septic tank, the depth of the water to be treated in the activated sludge treatment tank is formed to be the same as the depth of the water to be treated in the primary treatment tank. Has divided the inside of a cylindrical septic tank body having the same inner diameter to form the activated sludge treatment tank and the primary treatment tank.

[0003] In addition, an aerobic tank, such as an activated sludge treatment tank, for performing biological treatment with aerobic bacteria needs to supply a large amount of oxygen. Usually, air is supplied into the aerobic tank. Although it was configured to supply oxygen into the aerobic tank, a dispersing tube was provided to increase the depth of the water to be treated. It is considered advantageous to take large amounts. When the activated sludge treatment tank is provided with a membrane separation tank having a membrane separation device installed therein, in order to install a membrane separation device having a large filtration area, the water to be treated in the activated sludge treatment tank is provided. It is desired to increase the accommodation depth, and in any case, it is desired to increase the treatment water accommodation depth of the activated sludge treatment tank. Therefore, it has been considered that both the primary treatment tank and the activated sludge treatment tank are designed deeply as a whole to increase the depth of the activated sludge treatment tank to accommodate the water to be treated.

[0004]

However, although the septic tank is generally buried and used, if the entire septic tank is simply designed deep as described above, a large hole for burying the septic tank for embedding the septic tank is excavated. However, there is a drawback that civil engineering work associated with the burial work becomes difficult and the cost of the civil engineering work increases. From the viewpoint of the burial work, it has been desired that the entire septic tank be formed shallow.

This conflicts with the above-mentioned demand for improving the efficiency of supplying oxygen to the activated sludge treatment tank and the efficiency of processing to improve the efficiency of filtration. It was difficult to do.

Accordingly, an object of the present invention is to provide a purification tank capable of improving the treatment efficiency of the water to be treated in the activated sludge treatment tank without hindering the burying work in view of the above-mentioned circumstances.

[0007]

A first feature of the present invention to achieve this object is a purification tank provided with a primary treatment tank and an activated sludge treatment tank in this order from the inlet side of raw water to be treated. The storage depth of the water to be treated in the activated sludge treatment tank is formed larger than the storage depth of the water to be treated in the primary treatment tank , and the activated sludge treatment tank has a denitrification tank and a membrane.
A membrane separation tank equipped with a separation device is provided.
Natural flow of natural water from the denitrification tank to the membrane separation tank
And the water to be treated in the membrane separation tank is returned to the denitrification tank.
There that is provided with a treatment water return means for feeding, the
In the first characteristic configuration, the primary treatment tank includes a biological filtration tank or an anaerobic filter bed tank for filtering water to be treated, and the water to be treated or the anaerobic filter bed tank filtered in the biological filtration tank is used. May be provided with an advection mechanism for advancing the water to be treated to the activated sludge treatment tank , wherein the primary treatment tank includes a flow rate adjustment tank, and the flow rate adjustment tank has a flow rate adjustment tank. An advection mechanism for quantitatively advancing the water to be treated from the adjusting tank to the activated sludge treatment tank may be provided . The second feature of the present invention for achieving this object is as follows.
The feature composition is the primary treatment tank from the inlet side of the raw water to be treated,
In a septic tank provided with an activated sludge treatment tank in order,
The storage depth of the water to be treated in the sludge treatment tank
Formed to be larger than the depth of the water to be treated in the treatment tank, and provided with a denitrification tank in the primary treatment tank, and the activated sludge treatment tank was constituted by a membrane separation tank equipped with a membrane separation device, The water to be treated is configured so that it can freely flow from the denitrification tank to the membrane separation tank, and the water to be treated in the membrane separation tank is provided with a treated water return means for returning the water to the denitrification tank.
is there. The operation and effect of the above configuration are as follows.

[0008]

In other words, the storage depth of the water to be treated in the activated sludge treatment tank is formed larger than the storage depth of the water to be treated in the primary treatment tank, so that the entire septic tank is not formed deep. Only the activated sludge treatment tank can be formed deeper than before to constitute a purification tank, whereby
When supplying air to the activated sludge treatment tank, air can be diffused from a deep position in the water to be treated. Since the bubbles supplied to the activated sludge treatment tank move along a long path from a deep position to the surface of the water, the bubbles and the water to be treated sufficiently come into contact with each other. Since the oxygen dissolving efficiency is high, the oxygen can be satisfactorily dissolved from the bubbles into the water to be treated. Further, in the case where the activated sludge treatment tank includes a membrane separation tank in which a membrane separation device is installed, the water to be treated rises in the tank due to the bubbles generated by the aeration from the deep position. The membrane separation device can be arranged at a position where the flow rate is fast, and by arranging the membrane separation device at a position where the flow rate of the water to be treated is fast, the effect of efficiently cleaning the membrane surface of the membrane separation device can be obtained. Also, clogging of the film surface can be suppressed.

Further, a denitrification tank is provided in the activated sludge treatment tank.
And a membrane separation tank equipped with a membrane separation device.
The water to be treated is naturally transferred from the denitrification tank to the membrane separation tank.
It is configured to flow freely, and the water to be treated in the membrane separation tank is denitrified.
If there is a means for returning treated water to be returned to the tank,
Oxygen supply is sufficient in the membrane separation tank even for heavy water to be treated.
And nitrification of the water to be treated
Biological treatment for conversion to nitrogen)
The interior can be maintained under relatively low oxygen supply conditions,
The nitrified water to be treated is denitrified in a denitrification tank (nitrate nitrate).
Biological treatment that converts nitrogen into nitrogen gas)
The treated water becomes highly purified and the treated water
Has the advantage that the processing capacity of
You. In addition, a membrane separation tank equipped with a membrane separation device is adopted.
In this way, the activated sludge treatment tank can be formed small and large.
Septic tanks can be buried without forming vertical holes
Work can be done easily.

[0010] Further , the primary treatment tank filters the water to be treated.
Including a biological filtration tank or an anaerobic filter bed tank,
The water to be treated filtered in the biological filtration tank or the anaerobic filter bed
Transfer of the water to be treated that has passed through the tank to the activated sludge treatment tank.
If the flow mechanism is provided, the activated sludge treatment tank
The biological filtration in the biological filtration tank, or
Solids removed by anaerobic treatment in the filter bed tank
Water will be advected and will be treated in the activated sludge treatment tank.
Water treatment performance (activity) does not easily decrease.

Further , the primary treatment tank includes a flow control tank.
The flow control tank is provided with the flow control tank.
To quantitatively transfer the water to be treated to the activated sludge treatment tank
If an advection mechanism is provided, a fixed amount can be supplied to the activated sludge treatment tank.
Water in the activated sludge treatment tank
Is easily maintained at a constant level, and is constantly covered in the activated sludge treatment tank.
Even if the treated water is treated, the water quality in the activated sludge treatment tank
The aerobic treatment of the water to be treated can be performed stably without lowering the water content.

[0012]

Therefore, when the entire septic tank is formed deeply, a deep hole must be formed to bury the septic tank, which requires a great deal of labor for embedding. The septic tank can be buried without significantly lowering the properties, and the treatment efficiency of the water to be treated has been improved, so that the treated liquid that has been treated is likely to be sufficiently purified, The quality of the discharged treated water to be treated can be improved, which helps to reduce environmental pollution such as water pollution, and is advantageous for achieving low pollution at a low cost.

[0013] Further, since the activated sludge treatment tank can be made to have a structure in which the activity is hardly reduced, the purification tank can be used stably for a long period of time.

[0014]

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

As shown in FIG. 1, the septic tank according to the present invention comprises a primary treatment tank 1 and an activated sludge treatment tank 2 which are separate from the inlet I of raw water to be treated. The primary treatment tank 1 is provided with a sedimentation separation tank N1 and a biological filtration tank B1 so as to be connected by a communication pipe J so as to flow in this order.
The activated sludge treatment tank 2 is composed of a denitrification tank N2 and a membrane separation tank E.

The primary treatment tank 1 divides an inner space of a container having a height of about 1.4 m into two chambers, and a sedimentation separation tank N1 and a biological filtration tank B1 having an accommodation depth of about 1.2 m. Is formed. The sedimentation separation tank N1 receives the raw water to be treated that has flowed into the primary treatment tank 1, temporarily stores the water to be treated, and precipitates and separates impurities contained in the raw water,
The water to be treated is anaerobically decomposed by anaerobic bacteria living inside. The biological filtration tank B1 is adapted to interior aerobic filter bed C, the lower the aerobic filter bed C is provided with a diffusion pipe D1 to the air supply for its aerobic filter bed C, Koki濾The water to be treated passing through the floor C can be aerobicly decomposed and treated in a state where sludge is small. Further, a U-shaped pipe U is erected on the biological filtration tank B1, and the U-shaped pipe U is opened at one end above the aerobic filter bed C in the biological filtration tank B1, and the aerobic The biologically filtered water to be treated that has passed through the filter bed C is configured to be freely taken in, and the other end of the advection tube A
1 and the air to be supplied from the blower to the bottom of the U-shaped pipe U, the water to be treated in the biological filtration tank B1 is activated sludge through the U-shaped pipe U and the advection pipe A1 by an air lift action. An advection mechanism A for advancing to the processing tank 2 is configured. The advection pipe A1 is connected to a communication pipe J that communicates between the primary treatment tank 1 and the activated sludge treatment tank 2, and the water to be treated is subjected to the primary treatment through the communication pipe J. A flow is transferred from the tank 1 to the activated sludge treatment tank 2. The communication pipe J has a check valve V for preventing backflow.
The activated sludge in the activated sludge treatment tank 2 (the sludge in which a large number of aerobic bacteria are densely packed in the suspended sludge) flows back and the like, so that the concentration is hardly reduced. It is easy to keep the activity in the sludge treatment tank 2 high,
In addition, the configuration is such that the activated sludge is prevented from flowing back into the biological filtration tank B1 to easily clog the aerobic filter bed C.

The activated sludge treatment tank 2 has a height of about 1.8.
The interior space of the m container is divided into two chambers to form a denitrification tank N2 and a membrane separation tank E having a depth of about 1.4 m for the water to be treated. The denitrification tank N2 is configured to receive and temporarily store the water to be treated that has flowed from the biological filtration tank B1, and a circulation pump P1 is disposed inside the denitrification tank N2. It is configured to constantly circulate water. The membrane separation tank E contains a high concentration of activated sludge,
A high-concentration BOD contained in the water to be treated is configured to be biologically treatable, and a membrane separation device M configured by arranging a large number of flat membranes in parallel is provided therein. A diffuser D2 is provided below the membrane separator M to supply air bubbles to prevent sludge and the like from adhering to the flat membrane surface. Oxygen is supplied to the aerial bacteria, and the surface of the flat membrane is configured to be washable so that the membrane separation treatment performance of the flat membrane can be maintained at a high level. A discharge pump P2 for suction-filtering and discharging the water to be treated from the flat membrane and discharging the same is connected to the flat membrane so that highly purified water to be treated can be taken out. Further, an air lift pump A2 is erected in the membrane separation tank, and water to be treated in the membrane separation tank E is supplied to the denitrification tank N by air supply from a blower.
2 is provided so as to be freely returned.

When the water to be treated flows into the septic tank having such a structure, the raw water to be treated flowing into the primary treatment tank 1
Anaerobic treatment is performed while impurities are removed in the sedimentation separation tank N1, and the water to be treated after the anaerobic treatment flows naturally and flows into the biological filtration tank B1 from below. The water to be treated that has flowed into the biological filtration tank B1 rises while being subjected to biological filtration, and flows into the U-shaped pipe U in a state where there is little mixing of sludge. The water to be treated that has flowed into the U-shaped pipe U flows into the denitrification tank N2 via the advection mechanism A, and flows to the membrane separation tank E while being decomposed by the activated sludge in the denitrification tank N2. The water to be treated, which has flowed into the membrane separation tank E, is returned to the denitrification tank N2 again or filtered by the membrane separation device M while undergoing aerobic decomposition and nitrification by air supply from the diffuser D2. Or The returned to-be-processed water is one in which the denitrification action is favorably performed and the to-be-treated water is highly purified because the denitrification tank N2 is slightly more anaerobic than the membrane separation tank E. And the quality of the water to be circulated in the activated sludge treatment tank 2 is further improved. Therefore, the quality of the water to be treated, which is filtered from the membrane separation device M in the membrane separation tank E, is improved, and the membrane separation device M provides a treated liquid with almost no mixing of sludge. Water quality will be highly purified.

When such a septic tank is installed, the vertical hole for burying the septic tank to be formed by excavating from the ground is formed only partially larger than the size formed by the conventional civil engineering work. It was possible to install a septic tank with a high treatment capacity without increasing the labor required for installation.

[Another embodiment] Another embodiment will be described below.
The primary processing tank 1 having the following configuration may be used in place of the primary processing tank 1 in the above embodiment. Primary treatment tank 1 shown in FIG.
Has an inner space divided into two chambers, and a sedimentation separation tank N1 and a flow rate adjustment tank B2 are formed. The flow rate adjusting tank B2 is
A screen S that crushes or separates solids contained in the water to be treated and passes mainly a liquid having a high fluidity is installed, and air bubbles are supplied to the screen S, and solids trapped on the screen S are provided. Is further provided therein. In addition, the flow control tank B2
An advection pump P3 for quantitatively pumping the water to be treated therein is provided therein, and constitutes an advection mechanism A capable of quantitatively transferring the water to be treated containing little solid matter to the activated sludge treatment tank 2.
According to such a configuration, even if a large amount of raw water flows into the primary treatment tank 1, the activated sludge treatment tank 2
In this manner, the water to be treated can be constantly treated, and the treated liquid having a stable water quality can always be discharged without lowering the water quality in the activated sludge treatment tank 2.

Further, in the primary treatment tank 1, instead of the biological filtration tank, an anaerobic filter tank containing an anaerobic filter bed or an aerobic filter bed for growing aerobic bacteria is provided. An aerobic filter bed tank equipped with an air diffuser below the air filter bed, or a sedimentation tank that precipitates sludge in the water to be treated and reduces the content of solids may be included. It is preferable that the solid matter contained in the raw water is roughly treated, and the solid matter is hardly contained in the treated water flowing to the activated sludge treatment tank. It is unlikely that water treatment capacity will decrease,
It can be used stably for a long time. Further, the configuration may be changed such as using an anaerobic filter bed tank instead of the precipitation separation tank.

Further, the activated sludge treatment tank 2 also includes:
Although the example in which the interior is divided into two tanks is shown, the activated sludge treatment tank 2 may be composed of only one tank.
The activated sludge treatment tank 2 is desirably constituted by a membrane separation tank E in which a membrane separation device M is installed, and by employing the membrane separation tank E, stable treatment of the water to be treated can be performed. The water quality of the treated liquid can be kept high. Further, in such a case, it is preferable that the denitrification tank is formed in the primary treatment tank, and the primary treatment tank is provided with a denitrification tank, and the activated sludge treatment tank is equipped with a membrane separation device. A membrane separation tank, the water to be treated is configured to freely flow from the denitrification tank to the membrane separation tank, and the water to be treated in the membrane separation tank is returned to the denitrification tank. If the means is provided, the water to be treated can be highly purified as in the previous embodiment.

Further, the primary treatment tank 1 and the activated sludge treatment tank 2 may be integrated without being formed in separate containers. Further, the size is not limited to that shown in the above embodiment, and can be designed in various forms.

Further, the membrane separation device M may be provided not only at the lower part but also over the entire length in the depth direction.
Specifically, the membrane separation devices M may be provided in two stages. Also, it may be provided only on the upper part.

The advection mechanism A for advancing the water to be treated from the primary treatment tank 1 to the activated sludge treatment tank 2 is not limited to a mechanism for advancing the water to be treated quantitatively or in a state in which solids are removed. Instead, it may have a simple configuration in which the water to be treated is simply advected.

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the configuration shown in the accompanying drawings.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view of a septic tank in an embodiment.

FIG. 2 is a vertical sectional side view of a septic tank in another embodiment.

[Explanation of symbols]

 I Inflow pipe 1 Primary treatment tank 2 Activated sludge treatment tank B1 Biological filtration tank B2 Flow control tank E Membrane separation tank M Membrane separation device N2 Denitrification tank A2 Treated water return means

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI C02F 3/34 101 C02F 3/34 101B (72) Inventor Masaharu Iwahashi 2 in Takamatsu, Kosai-cho, Koga-gun, Shiga Prefecture Inside Kubota Shiga Plant Co., Ltd. (72) Inventor Katsumi Hamada 2nd Takamatsu, Kosai-cho, Koga-gun, Shiga Prefecture Inside the Kubota Shiga Plant, Inc. (56) References Attached to the application form Japanese Utility Model Application No. 1-147526 (Japanese Utility Model Application No. 3-86094). Microfilm (JP, U) photographing the contents of the specification and drawings attached The microfilm (JP, U) photographing the contents of the specifications and drawings attached to the application for Japanese Utility Model Application No. Hei 3-12704 (Japanese Utility Model Application No. Hei 4-99291) JP, U) "Sewage Septic Tank Handbook" by Shigeru Ohno (November 26, 1956) Industrial Water Research Committee p120-125, p238-241, p268 (58) Fields surveyed (Int. Cl. ⁷ , DB name) C02F 3/12 C02F 3/00

Claims (5)

(57) [Claims] 1. A purifying tank provided with a primary treatment tank (1) and an activated sludge treatment tank (2) in this order from the inlet (I) side of raw water to be treated, wherein the activated sludge treatment tank (2) The storage depth of the water to be treated is formed larger than the storage depth of the water to be treated in the primary treatment tank (1) , and the activated sludge treatment tank (2) is provided with a denitrification tank (N2) and a membrane.
When a membrane separation tank (E) containing a separation device (M) is installed,
In both cases, the water to be treated is removed from the denitrification tank (N2)
The separation tank (E) is configured to be freely advected naturally, and the membrane separation tank
Return the water to be treated in (E) to the denitrification tank (N2)
A septic tank provided with a treated water return means (A2) . 2. The primary treatment tank (1) includes a biological filtration tank (B1) for filtering water to be treated, and the water to be treated filtered in the biological filtration tank (B1) is treated with the activated sludge. An advection mechanism for advancing to the processing tank (2) is provided.
The septic tank described in 1. 3. The primary treatment tank (1) includes an anaerobic filter tank for filtering water to be treated, and the water to be treated from the anaerobic filter tank is supplied to the activated sludge treatment tank (2). The septic tank according to claim 1, further comprising an advection mechanism for advection. 4. The primary treatment tank (1) includes a flow rate adjusting tank (B2), and the flow rate adjusting tank (B2) is provided with the activated sludge treatment tank (B) from the flow rate adjusting tank (B2). The septic tank according to any one of claims 1 to 3, further comprising an advection mechanism for quantitatively advancing the water to be treated to 2). 5. A method according to claim 1, wherein the raw water is treated in one direction from an inlet (I) side of the raw water.
Purification with the next treatment tank (1) and activated sludge treatment tank (2)
And the depth of storage of the water to be treated in the activated sludge treatment tank (2).
Is the storage depth of the water to be treated in the primary treatment tank (1).
When the primary treatment tank (1) is provided with a denitrification tank (N2)
In addition, the activated sludge treatment tank (2) is connected to a membrane separation device (M).
And a membrane separation tank (E) containing
Is naturally transferred from the denitrification tank (N2) to the membrane separation tank (E).
It is configured to flow freely, and the water to be treated in the membrane separation tank (E) is
Means for returning treated water (A ) to be returned to the denitrification tank (N2)
A septic tank provided with 2) .