JPH1157765A - Septic tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stop a solid-liq separation by a membrane separation device in a short time at a non-aeration time and also to realize it inexpensively and conveniently. SOLUTION: In this specific tank, a treated water storage tank 18 arranged at the upward position of a water treating tank 6 is connected to the poststage of a discharge pump 12 in a discharge pipe 15. A return pipe 19 facing the water treating tank 6 is connected to the treated water storage tank 18, the treated water is lifted with the discharge pump 12 and the treated water stored temporarily is returned to the water treating tank 6 in the case when the discharge pump 12 is stopped.

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 capable of stopping solid-liquid separation by a membrane separation device in a short period of time in a non-aeration state, and inexpensively and easily realizing the solid-liquid separation.

[0002]

2. Description of the Related Art Conventionally, daily cooking, including night soil,
Septic tanks capable of purifying domestic wastewater generated by washing, bathing, and the like have been provided. One of the septic tanks is, for example, a membrane-separated septic tank shown in FIG. As shown in FIG. 7, in the membrane separation type septic tank, a membrane separation device (5) converts wastewater into an aeration tank (4) for aerobically biologically treating wastewater with activated sludge. The interior is immersible. The membrane separation device (5) performs solid-liquid separation of the sewage in the aeration tank (4) using the head difference between the aeration tank (4) and the treated water tank (6) as a driving pressure. To this end, the lower end of the filtrate pipe (9) connected to the membrane separation device (5) is connected to a discharge pipe (15) extending from the treated water tank (6) in the treated water tank (6), and the treated water is discharged. It is arranged below the lowest operable water level of the discharge pump (12) for pumping water. In the solid-liquid separation by the membrane separation device (5), the activated sludge remains in the aeration tank (4), and only the treated water enters the treatment water tank (6) communicating with the aeration tank (4) through the filtrate pipe (9). Sent.

[0003] The treated water is then pumped up from a treated water tank (6) by a discharge pump (12), and is discharged from a discharge pipe (1).
It is sent to the disinfection tank (8) through 5), and then discharged outside the tank. In such a membrane type septic tank, a sedimentation separation tank (1) and an anaerobic bed tank (2) can be provided on the wastewater inflow side as a contaminant removal tank, and the treated sewage is transferred to a transfer pump (3). ) To be sent to the aeration tank (4). Reference numeral 14 denotes a sludge transfer pipe that forms a transfer passage for sludge.

The aeration tank (4) is further provided with an air diffuser (7), and air blown from a blower (16) connected to the air diffuser (7) is supplied to the air diffuser (7). ) To the aeration tank (4) so that an aerobic state is formed. Then, in the septic tank, the water levels of the impurity removing tank (for example, the sedimentation separation tank (1) and the anaerobic filter tank (2)) and the aeration tank (4) are adjusted by the water level of the impurity removing tank and the aeration tank (4). Water level detection means (11, 13) provided in each of them detects the water level, and the operation of the transfer pump (3) can be controlled by the control unit (10) according to the detected water level. In the control unit (10), the maximum and minimum limit water levels (L1, L2) in each tank (1, 2, 4) are set as a reference for operation control of the transfer pump (3).

For example, in the membrane separation type septic tank shown in FIG. 7, as described above, the driving pressure of the solid-liquid separation of the sewage by the membrane separation device (5) is increased by the aeration tank (4) and the treated water tank (6). Since the head is obtained from the natural head, the driving means such as a pump is unnecessary, the structure is simplified, and there is an advantage that the cost can be reduced.

[0006]

However, in this membrane separation type septic tank, if the aerobic (aerated) state and the non-aerobic (non-aerated) state are alternately repeated for the purpose of nitrogen removal, There is a concern that the separation device (5) may be clogged. That is, in the case of aeration, the membrane surface is cleaned by the aerated air flow sent through, for example, the air diffuser (7). However, the aerated air flow is not supplied in the non-aerated state. Such a cleaning effect cannot be expected. In such a state, the solid-liquid separation of the wastewater is performed, and if this is repeated, the membrane separation of the membrane separation device (5) naturally occurs and proceeds.

Therefore, it has been studied to temporarily stop the solid-liquid separation by the membrane separation device (5) when not aerated, and several specific measures have been considered. However, at present, all of them have some problems in practical use. For example, there is a method in which the discharge pump (12) is stopped before switching to the non-aeration mode, and the heads of the aeration tank (4) and the treatment water tank (6) are matched. However, in this case, if the membrane blockage of the membrane separation device (5) is progressing (in the septic tank, the membrane blockage occurs gradually with the operation), it takes time until the water heads coincide with each other, and the treatment is performed. There is a risk that the ammonia content of the water will increase.

On the other hand, there is a proposal that an electromagnetic valve is provided in the filtrate pipe (9), and the filtrate pipe (9) is shut off by the solenoid valve when the air is not aerated. However, in this case, the solenoid valve
Reliability is required in an atmosphere where ammonia gas is generated in a humid environment such as a septic tank. Therefore, the solenoid valve becomes expensive, and maintenance work is required.

The present invention has been made in view of the circumstances described above, and solves the problem of stopping solid-liquid separation in a conventional membrane separation-type septic tank when it is not aerated. It is an object of the present invention to provide a septic tank capable of stopping solid-liquid separation by an apparatus in a short time and realizing this inexpensively and easily.

[0010]

Means for Solving the Problems The present invention solves the above-mentioned problems by providing a membrane separation device in a gas aeration tank for aerobically biologically treating sewage with activated sludge so as to be immersed in the sewage. A treatment water tank is provided in communication with the aeration tank through a filtrate pipe connected to the membrane separation device, and a lower end of the filtrate pipe is connected to a discharge pipe extending from the treatment water tank in the treatment water tank. The membrane separation device is disposed below the lowest operable water level of the discharge pump that pumps up water, and the membrane separation device uses the head difference between the aeration tank and the treatment tank as the driving pressure to separate the wastewater into solid and liquid, and the activated sludge is aerated. On the other hand, in the purification tank that sends the treated water to the treated water tank, a treated water storage tank disposed above the treated water tank is connected to a stage after the discharge pump of the discharge pipe, and the treated water tank is connected to the treated water tank. Return piping is connected, Is pumped by the flow pump, provides a septic tank, characterized in that it is a temporarily storing the treated water can return to the process water tank when stopping discharge pump.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The septic tank of the present invention will be described below in more detail with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing one embodiment of the septic tank according to the present invention.
In the drawings, components denoted by the same reference numerals as those shown in FIG. 7 indicate the same components as those shown in FIG. 7 and function similarly.

That is, in the septic tank shown in FIG.
The lower end of the filtrate pipe (9) is disposed below the lowest operable water level of the discharge pump (12) in the treated water storage tank (6) to form a siphon. The solid-liquid separation by the membrane separation device (5) is possible until the water levels in the aeration tank (4) and the treated water tank (6) match. As the membrane separation device (5), for example, as shown in FIG. 1, a unit having a plurality of flat membranes (17) suspended in parallel can be employed.

[0013] water level of the aeration tank (4) is in the first HWL, the water level is lowered according to the solid-liquid separation by membrane separation apparatus (5), whereas, although the water level h ₂ of the treating tank (6) is increased The head difference between the aeration tank (4) and the treatment tank (6)
Balancing and stabilizing where a water head difference indicating a membrane permeation flux corresponding to the discharge flow rate by the discharge pump (15) is obtained. In the septic tank of the present invention, as shown in FIG. 1, the treated water storage tank (18) is provided with the discharge pump (1) of the discharge pipe (15).
2) It is connected to the subsequent stage. This treated water storage tank (18)
Is disposed above the treated water tank (6), and is connected to a return pipe (19) toward the treated water tank (6).

As shown in FIG. 2A, when the discharge pump (12) is operating during aeration, the treated water in the treated water tank (6) is pumped up and the treated water storage tank (18). And temporarily stored in the treated water storage tank (18).
Thereafter, the treated water is discharged. When the discharge pump (12) stops during the transition to the non-aerobic (non-aerated) state, as shown in FIG. 2 <b>, the treated water storage tank (18)
The treated water stored in the tank is treated at once by a return pipe (19) based on the difference in height between the tanks caused by the arrangement of the treated water storage tank (18) above the treated water tank (6). Flow back into the water tank (6). As a result, the aeration tank (4)
The head difference between the water tank and the treated water tank (6) is reduced, the permeation of the membrane stops, and the solid-liquid separation of the membrane separator (5) stops.

As described above, in the septic tank according to the present invention, the solid-liquid separation by the membrane separation device (5) can be stopped in a short time during non-aeration, and this can be achieved by the discharge pipe (15).
And a treated water storage tank (18) arranged above the treated water tank (6) and a return pipe (1) connected to the treated water storage tank (18).
9) It is realized at low cost by the simple means. In order to remove nitrogen, an aerobic (aerated) state and a non-aerobic (non-aerated) state are alternately created in the aeration tank (4), and even if this is repeated, membrane clogging occurs in the membrane separation device (5). It will not be promoted.

FIG. 3 is a timing chart showing the operation states of the blower (blower) and discharge pump and the water levels of the aeration tank and the treated water tank in the septic tank of the present invention when aerated and not aerated. In the septic tank, a timer is provided in the control unit (10) and the time is set so that the aeration step and the non-aeration step are alternately repeated at predetermined time intervals. Further, it is also possible to detect ORP (oxidation-reduction potential), pH, and the like, and automatically switch to the non-aeration mode based on the detected ORP (oxidation-reduction potential) and pH. When the mode shifts to the non-aeration mode, the control unit (10) commands the stop of the discharge pump (12), and the discharge pump (12) stops.

In addition, in the septic tank of the present invention, FIG.
As shown in (2), the discharge pump (12) is also stopped when the aeration tank (4) reaches the lowest water level LWL, and the discharge pump (12) based on the detection of the lowest water level LWL of the aeration tank (4). The control of 12) can be prioritized to each control described above. In the aeration tank (4), as shown in FIG.
Since the water level detection means (13) can be provided, the water level detection by the water level detection means (13) is performed by the discharge pump (1).
This is fed back to the control of 2). That is, when the minimum water level LWL of the aeration tank (4) is detected by the water level detection means (13), the control unit (10) shown in FIG. 7 commands the stop of the discharge pump (18). There is no particular limitation on the applicable water level detecting means (13). Various types such as a float sensor and a pressure sensor can be appropriately selected and employed.

Further, in the septic tank according to the present invention, the return amount of the treated water returned from the treated water storage tank (18) to the treated water tank (6) upon shifting to the non-aeration step, that is, the treatment water storage tank (18) The water storage amount can be set to an amount that is equal to or higher than the minimum water level LWL of the aeration tank (4) at the end of the membrane life of the membrane separation device (5). In this case, the treated water tank (6)
If the cross-sectional area is made smaller and elongated, the amount of water returned is reduced even at the same water level, and the amount of water stored in the treated water storage tank (18) can be reduced. It contributes to downsizing of septic tanks.

Further, in the septic tank of the present invention, as shown in FIG. 1, the treated water storage tank (18) of the discharge pipe (15).
A constant flow valve (20) can be provided at a subsequent stage. The constant flow valve (20) is a valve that keeps the discharge flow constant. When the discharge flow becomes constant, the balance water level shifts downward with time as shown in FIG. (5)
Can be constant. As the applicable constant flow valve (20), various types including a conventionally known one can be adopted.

Further, the constant flow valve (20) can be replaced with the regulating valve (21) shown in FIG. Adjusting valve (2
1) is a valve capable of changing the discharge flow rate according to the opening degree, and is adjusted to an appropriate opening degree according to the discharge flow rate. The treated water pumped up by the discharge pump (12) through the discharge pipe (15) is discharged from the treated water storage tank (18) at a constant discharge flow rate according to the opening of the regulating valve (21).

Further, when a constant flow valve (20) is provided, as shown in FIG. 5, the discharge pipe (15) branches off in front of the treated water storage tank (18), and a constant flow A valve (20) can also be provided. In this case, the treated water pumped up from the treated water tank (6) by the discharge pump (12)
A part thereof is discharged at a constant discharge flow rate by the constant flow valve (20) while being guided to the treated water storage tank (18). This constant flow valve (20) can be replaced with a simple on-off valve.

In the septic tank shown in FIG. 6, the discharge pipe (1
Instead of providing a constant flow valve (20) and a regulating valve (21) in 5), an overflow weir (22) is provided in the treated water storage tank (18). The treated water storage tank (18) includes the overflow weir (22)
Thus, it is divided into a storage side (23) and an overflow side (24), and a discharge pipe (15) is connected to the storage side (23). The treated water pumped up by the discharge pump (12) is guided to the storage side (23) and is temporarily stored. When the treated water reaches a predetermined amount or more, it flows over the overflow weir (22) from the storage side (23). It overflows to the flow side (24) and is discharged at a constant discharge flow rate.

The above constant flow valve (20) and regulating valve (21)
As described above, the overflow weir (22) makes the discharge flow constant and makes it possible to make the membrane permeation flux of the membrane separation device (5) constant, but also changes the discharge flow. Is also easy. In other words, when a discharge pump (12) having a capability of realizing a predetermined pumping amount (for example, a pumping amount of 10 or more tanks) is adopted, the adjustment of the discharge flow according to the tanks is performed by adjusting the constant flow valve. (20), it is easily realized by the regulating valve (21) and the overflow weir (22).

For example, in the case of the constant flow valve (20) shown in FIGS. 1 and 5, a valve which realizes an appropriate flow according to the human tub is adopted or replaced. In the case of the treated water storage tank (18) in which the overflow weir (22) shown in FIG.
The overflow weir (22) is notched in a triangular shape at its center, for example, and scales for displaying the discharge flow rate corresponding to the human tank are provided along the top and bottom on the upper surface of the cutout part. Then, the treated water storage tank (1) when overflowing the overflow weir (22)
The pumping amount of the discharge pump (12) is adjusted so that the water level in 8) matches the scale according to the human tank.

It should be noted that reference numeral 25 shown in FIGS.
Indicates a contaminant removal tank. This contaminant removal tank (2
5) can be composed of, for example, a sedimentation separation tank (1) and an anaerobic filter bed tank (2) as shown in FIG. Reference numeral 26 denotes a water level detecting means for detecting the water level of the treated water tank (6). As the discharge pump (12), for example, a submersible pump or the like can be employed, but there is a case where idling of the discharge pump (12) becomes a problem. In order to prevent such an idle operation of the discharge pump (12),
The water level of the treated water tank (6) detected by the water level detecting means (26) is fed back to the control of the discharge pump (12). This can prevent the water level in the treated water tank (6) from falling below the minimum water level at which the discharge pump (12) can operate. The discharge pump (12) and the water level detecting means (26) are each connected to a control unit (10) as shown in FIG.

As the discharge pump (12), besides a submersible pump, an air lift pump, a pneumatic pump, or the like can be adopted. Depending on the type of pump, the water level detecting means (2) may be used.
Step 6) can be omitted. Of course, the present invention is not limited by the above embodiments.
It goes without saying that various aspects are possible for details such as the structures of the tanks and membrane separation devices provided in the septic tank, the discharge pump, the treated water storage tank, and the like.

[0027]

As described above in detail, according to the present invention, the solid-liquid separation by the membrane separation device can be stopped in a short time in the non-aeration state, and this can be realized inexpensively and simply.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing one embodiment of a septic tank according to the present invention.

FIGS. 2A and 2B are main-portion cross-sectional views of the septic tank shown in FIG.

FIG. 3 is a timing chart showing the operation states of a blower (blower) and discharge pump and the water levels of the aeration tank and the treated water tank in the septic tank of the present invention during aeration and non-aeration.

FIG. 4 is a cross-sectional view of a main part schematically showing another embodiment of the septic tank of the present invention.

FIG. 5 is a cross-sectional view of a main part schematically showing another embodiment of the septic tank of the present invention.

FIG. 6 is a sectional view schematically showing another embodiment of the septic tank according to the present invention.

FIG. 7 is a cross-sectional view schematically showing a membrane separation type septic tank.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 sedimentation separation tank 2 anaerobic filter bed tank 3 transfer pump 4 aeration tank 5 membrane separation device 6 treatment water tank 7 diffuser tube 8 disinfection tank 9 filtrate tube 10 control unit 11 water level detection means 12 discharge pump 13 water level detection means 14 transfer pipe 15 discharge pipe 16 blower 17 flat membrane 18 treated water storage tank 19 return pipe 20 constant flow valve 21 regulating valve 22 overflow weir 23 storage side 24 overflow side 25 impurity removal tank 26 water level detection means

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koji Minami 1048 Kadoma Kadoma, Osaka Pref.Matsushita Electric Works, Ltd. (72) Inventor Shigeyuki Yamaguchi 1048 Kadoma Kadoma, Osaka Pref.Matsushita Electric Works Co., Ltd. (72) Inventor Hitoshi Kitamura 1048 Kadoma, Kazuma, Osaka Prefecture Matsushita Electric Works, Ltd.

Claims (5)

[Claims] An aeration tank for aerobically biologically treating sewage with activated sludge is provided with a membrane separator so as to be immersed in the sewage, and a treatment water tank is exposed through a filtrate pipe connected to the membrane separator. The lower end of the filtrate pipe is provided in communication with the air tank, and the lower end of the filtrate pipe is connected to a discharge pipe extending from the treatment water tank in the treatment water tank, and is disposed below a minimum operable water level of a discharge pump that pumps up the treatment water. The membrane separation device separates the sewage into solid and liquid by using the head difference between the aeration tank and the treatment tank as the driving pressure, and keeps the activated sludge in the aeration tank while sending the treatment water to the treatment tank. The treated water storage tank located at the upper part of the tank is connected to the discharge pipe after the discharge pump, and the return pipe connected to the treated water tank is connected to this treated water storage tank, and the discharged water is pumped by the discharge pump and temporarily stored. Discharge pump for discharged treated water A septic tank characterized in that it can be returned to the treated water tank when it is stopped. 2. The purification tank according to claim 1, wherein a constant flow valve is provided at a stage subsequent to the treated water storage tank in the discharge pipe. 3. The purification tank according to claim 1, wherein an adjustment valve is provided at a stage subsequent to the treated water storage tank in the discharge pipe. 4. The purification tank according to claim 1, wherein the discharge pipe branches before the treated water storage tank, and a constant flow valve is provided in the branch passage. 5. The septic tank according to claim 1, wherein the treated water storage tank includes an overflow weir.