JP3384684B2 - Septic tank - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a septic tank. More specifically, the present invention relates to a septic tank that can return excess sludge in the agitation tank with a simple structure and can contribute to downsizing and cost reduction.

[0002]

2. Description of the Related Art Conventionally, with the increasing tendency to protect the global environment, septic tanks have been installed in household units,
At the same time, there is a movement to purify the domestic wastewater generated by daily cooking, washing, bathing, etc. As one of the septic tanks, for example, a membrane separation type septic tank shown in FIG. 4 is known.

The septic tank is provided with a sedimentation separation tank (1), an anaerobic filter bed tank (2), an aeration tank (3), and a disinfection tank (4) in this order from the drainage inflow side to the discharge side. The wastewater guided to the septic tank first enters the sedimentation separation tank (1), where impurities are removed. Then, it enters the anaerobic filter bed tank (2) communicating with the precipitation separation tank (1) and is subjected to anaerobic treatment. After this, the dirty water is sent to the agitation tank (3) by the operation of the transfer pump (5).

The aeration tank (3) is provided with an air diffuser pipe (6), and air is supplied from a blower (7) connected to the air diffuser pipe (6) to make it aerobic. The sewage treated by the activated sludge in the batter tank (3) then passes through the separation membrane (9) also provided in the tank by the operation of the suction pump (8), is filtered, and is disinfected in the sterilization tank (4). Sent to. The filtered water is discharged after being treated in the disinfection tank (4).

The above transfer pump (5), blower (7),
The suction pump (8) and the suction pump (8) are electrically connected to the control unit (10) so that the operations thereof are performed optimally. In such a septic tank, the sedimentation separation tank (1) and the anaerobic filter bed tank (2) are used as flow rate adjusting tanks so that the membrane treatment by the separation membrane (9) in the aeration tank (3) is effectively performed. , It alleviates fluctuations in the amount of inflowing wastewater. The flow rate adjusting tank is provided with water level detecting means (11) for detecting the upper and lower limit water levels (L1, L2) of the dirty water. The water level detection means (11) is electrically connected to the control part (10), and the operation of the transfer pump (5) corresponding to the upper and lower limit water levels (L1, L2) detected by the water level detection means (11). Are trying to control.

Further, in this septic tank, the upper and lower limit water levels (L1, L1) are set in order to prevent overflow of sewage and to keep the separation membrane (9) in water even in the aeration tank (3).
L2) is set, and this is detected by the water level detection means (12). The water level detecting means (12) is also electrically connected to the control unit (10), and the operations of the transfer pump (5) and the suction pump (8) are controlled in accordance with the detected water level.

[0007]

However, for example, in the conventional membrane separation type septic tank shown in FIG. 4, when the sludge in the agglomeration tank (3) becomes excessive due to its operation, the separation membrane (9) will be exposed. Since the clogging progresses, there is a problem that the membrane suction pressure rises and the load of the suction pump (8) increases.

As a measure for solving this problem, it has been considered that the excess sludge in the aeration tank (3) is periodically withdrawn and returned to the flow rate adjusting tank. Conventionally, the sludge returning pump (13) is used. ) Is provided. However,
The installation of this sludge return pump (13) is too large and leads to an increase in the size of the septic tank. Moreover, the cost of the septic tank is inevitable. For household use, a compact and low-cost septic tank is particularly preferable, and the aeration tank (3)
It is desirable to have a method that makes it easier to return the excess sludge inside.

The present invention has been made in view of the circumstances as described above, solves the drawbacks of the conventional septic tank, and realizes the transfer of the excess sludge in the agitation tank with a simple structure and is compact. The object is to provide a septic tank that can contribute to cost reduction.

[0010]

As a solution to the above-mentioned problems, the present invention provides a septic tank provided with water level detection means for detecting the level of sewage water in an aeration tank equipped with a separation membrane. And the flow rate adjustment tank in the preceding stage communicates with each other at a position higher than the upper limit of the sewage water level in the flow rate adjustment tank, sets this position as the overflow level, and the water level detection means can detect this overflow level as well. The present invention provides a septic tank characterized by returning excess sludge in the aeration tank to the flow rate adjusting tank at the overflow level.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the septic tank of the present invention will be described in more detail with reference to the accompanying drawings.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a conceptual diagram showing an embodiment of the septic tank of the present invention. In the example shown in FIG. 1, the batter tank (3) and the flow rate adjusting tank consisting of the settling separation tank (1) and the anaerobic filter bed tank (2) in the preceding stage are the waste water in the flow rate adjusting tank. It communicates at a position higher than the upper limit water level (L2).
Specifically, a sludge return pipe (14) is provided, and the position of this sludge return pipe (14) is set as an overflow level.
This overflow level is set to L3 as the sewage water level of the batter tank (3), and the water level detection means (12) provided in the batter tank (3) detects the overflow level (L3). I am trying to make it possible.

For example, in the septic tank having the above structure,
When the sludge in the agitation tank (3) becomes excessive due to the operation, the separation membrane (9) easily becomes clogged,
By operating the transfer pump (5), the sewage water is transferred from the anaerobic filter bed tank (2) into the bubbling tank (3) until the overflow level (L3) is reached. At this time, the water level detection means (12)
Detects the overflow level (L3), but the control unit (10)
Controls the operation of the transfer pump (5) so that the sewage is not transferred above the overflow level (L3). The sewage in the batter tank (3) is temporarily at the normal upper water level (L
However, due to the rise in the water level at this time, the sludge in the batter tank (3) flows into the sludge return pipe (14) and heads for the flow rate adjusting tank. In the example of FIG. 1, the sludge flows out to the sedimentation separation tank (1). The sludge transfer to the overflow level (L3) by the transfer pump (5) can be performed, for example, periodically.

In this way, the excess sludge in the aeration tank (3) is returned to the flow rate adjusting tank. The excess sludge in the batter tank (3) can be returned by the simple method of controlling the liquid level in the batter tank (3), and the sludge return pump provided in the conventional septic tank can be eliminated. . Further, even if the separation membrane (9) is clogged, the membrane suction amount is reduced, and the sewage is about to overflow from the aeration tank (3), the sewage that overflows is returned to the sludge return pipe (14). It is possible to prevent the high-concentration activated sludge from the aeration tank (3) from being directly discharged to the flow rate adjusting tank through the above).

Moreover, in this septic tank, after the sewage water level in the batter tank (3) reaches the overflow level (L3), the transfer pump (5) is continuously operated and kept at the overflow level (L3). It is possible to set the sludge return amount corresponding to the generation amount of the excess sludge in the agitation tank (3) by changing the. FIG. 2 is a conceptual diagram showing another example of the septic tank of the present invention.

In the example shown in FIG. 2, the water level detecting tank (15) is provided so that the water level detecting means (12) can detect the water level of the sewage in the aeration tank (3) with higher accuracy. Is provided. The water level detection tank (15) has an opening (16) at the bottom, and this opening (16)
It communicates with the tank (3) through. Opening (1
6) does not necessarily have to be provided so as to face the bottom surface of the agitation tank (3), and may be arranged toward the separation membrane (9).
On the other hand, it is preferable that the opening (16) is arranged such that the center of the opening (16) is located at 50% or less of the water level when the tank (3) is full.

Further, as shown in the plan view of FIG. 3, the water level detecting means (12) is housed inside the water level detecting tank (15). The water level detection tank (15) may have at least a space for accommodating the water level detection means (12), and its cross-sectional area is, for example, 1/10 or less of the cross-sectional area of the aeration tank (3). be able to. In such a water level detection tank (15), the water level moves in conjunction with the water level of the aeration tank (3) communicating with the water level detection tank (15) and shows an average value in the water level of the aeration tank (3) and the transfer pump (5). When sewage is transferred from the plant and during aerobic treatment, it is not directly affected by the turbulence of the water surface. Therefore, the water level in the aeration tank (3) can be detected accurately.

In order to enable more accurate water level detection, as shown in FIG. 2, the pipe for transferring the sewage from the transfer pump (5) is provided near the bottom of the tank (3). It can also be connected to a lower position. Of course, the present invention is not limited to the above examples. Needless to say, various aspects are possible in details of the configuration and structure of each tank provided in the septic tank, the water level detection means, and the like.

[0019]

As described above in detail, according to the present invention, the excess sludge in the agitation tank can be transferred with a simple structure, and the septic tank can be made compact and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an embodiment of a septic tank of the present invention.

FIG. 2 is a conceptual diagram showing another example of the septic tank of the present invention.

FIG. 3 is a plan view of a main part of the example shown in FIG.

FIG. 4 is a conceptual diagram showing a conventional membrane separation type septic tank.

[Explanation of symbols]

1 sedimentation tank 2 Anaerobic filter bed tank 3 tank 4 disinfection tank 5 Transfer pump 6 Air diffuser 7 blower 8 suction pump 9 Separation membrane 10 Control unit 11,12 Water level detection means 14 Sludge return pipe 15 Water level detection tank 16 openings

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takayoshi Nakaoka 1048 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works, Ltd. (56) Reference JP-A-8-141585 (JP, A) JP-A-5- 96288 (JP, A) JP-A-8-84995 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C02F 3/00 C02F 3/12 C02F 3/28-3/34

Claims (3)

(57) [Claims] 1. In a septic tank provided with a water level detection means for detecting the level of wastewater in a tank equipped with a separation membrane, the tank and the flow rate adjusting tank at the preceding stage of the tank are Communication is made at a position higher than the upper limit, and this position is set as the overflow level, and the water level detection means is also capable of detecting this overflow level, and at the overflow level, the excess sludge in the aeration tank is adjusted to the flow rate adjustment tank. A septic tank characterized by being returned to. 2. The septic tank according to claim 1, wherein the amount of surplus sludge returned is variable depending on the time for which the level of the sewage water in the aeration tank is maintained at the overflow level. 3. The septic tank according to claim 1, further comprising a water level detection tank communicating with the bubbling tank, and the water level detection means being housed in the water level detection tank.