JP2001321791A - Method for storing waste sludge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for storing waste sludge, capable of storing waste activated sludge without generating a malodor by adjusting the concentra tion of activated sludge in an aerobic treatment tank to a proper concentration by an extremely simple method. SOLUTION: In the method for storing waste sludge by providing the aerobic treatment tank, wherein a filter film and an air diffuser are arranged to aerobically treat sewage with activated sludge to obtain treated water, and a sludge storage tank through a partition plate in an adjacent state, the aerobic treatment tank and the sludge storage tank are allowed to communicate with each other through the opening part formed to the lower part of the partition plate and activated sludge in the aerobic treatment tank is intermittently transferred to the sludge storage tank.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for treating human waste, domestic wastewater, kitchen wastewater or organic industrial wastewater pulverized by a disposer with activated sludge, and separating the solid and liquid with a filtration membrane installed in an activated sludge tank. The present invention relates to a method for storing excess sludge in a sewage treatment apparatus such as a septic tank for obtaining water.

[0002]

2. Description of the Related Art Conventionally, when organic wastewater is treated using activated sludge in an aerobic treatment tank, solid activated sludge is allowed to stand still in a sedimentation tank for sedimentation separation, and the supernatant liquid is discharged as treated water. are doing. In order to obtain a supernatant liquid efficiently, it is necessary to maintain the activated sludge concentration at a concentration of about 3000 mg / liter. When the concentration is increased, the ratio of the supernatant liquid in the sedimentation tank decreases, and the predetermined treated water An enormous area of sedimentation tank is required to obtain.

[0003] In recent years, a method has been adopted in which activated sludge and treated water are separated by a filtration membrane using a membrane separation device instead of a settling tank.
Processing tanks are being downsized by increasing the concentration to around mg / liter. However, as the treatment is continued, the activated sludge, which is an aggregate of microorganisms, repeats multiplication and further increases in concentration. Among them, inactivated sludge is included, and not only the efficiency of the treatment is lowered but also the viscosity of the treated water is increased due to the increased sludge concentration, and the fluidity is deteriorated.

[0004] A membrane separation device is installed in the aerobic treatment tank. Oxygen is supplied to the treated water by aeration from a diffuser installed immediately below a filtration membrane of the membrane separation device, and activated sludge is supplied. Are aerobically treating organic matter. In addition, treated water is obtained by performing a solid-liquid separation while the surface of the filtration membrane is washed by an ascending flow generated by the bubbles aerated by the air diffuser rising on the surface of the filtration membrane.

Therefore, when the concentration of the activated sludge becomes too high and the fluidity deteriorates, the ascending flow on the surface of the filtration membrane becomes uneven and the washing effect is not exhibited, and the sludge blocks the pores of the filtration membrane. This causes a problem in filtration. On the other hand, if the concentration of the activated sludge is too low, the biological amount required for the treatment becomes insufficient, so that the biological treatment cannot catch up and is discharged without treatment.

For this reason, Japanese Patent Application Laid-Open No. 11-262792 discloses a purification tank incorporating means for automatically adjusting the concentration of activated sludge in a treatment tank to an appropriate range. There has been proposed a method in which an activated sludge is extracted from an activated sludge tank when the concentration exceeds a set concentration, measured by an ultrasonic measuring device, and transferred to a sludge concentrated storage tank.

[0007] However, the conventional sludge storage tank is anaerobically settled and stored in the aerobic treatment tank and an independent tank separately provided without installing a diffuser. However, since it rots and generates a lot of bad smells, it is indispensable to take measures against such smells. As a means to prevent stored sludge from spoiling, a diffuser can be incorporated into the sludge storage tank to aerate and maintain an aerobic state to prevent the generation of odors.However, a separate blower is needed to supply oxygen. And there is a problem that extra power is required. In addition, the ultrasonic measurement device used as a means for measuring the sludge concentration is expensive, and furthermore, a control device for operating a drawing pump from the measurement result is required, so that the cost of the device becomes enormous. There was also.

[0008]

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, the present invention adjusts the activated sludge concentration in an aerobic treatment tank to an appropriate concentration by an extremely simple method, and eliminates excess activated sludge without generating odor. An object of the present invention is to provide a method for storing excess sludge that can be stored.

[0009]

According to the present invention, there is provided an aerobic treatment tank provided with a filtration membrane and an air diffuser, and aerobically treating sewage with activated sludge to obtain treated water; Is provided adjacently via a partition plate to store excess sludge, wherein the aerobic treatment tank and the sludge storage tank communicate with each other through an opening at a lower portion of the partition plate, and the aerobic treatment tank This is a method for storing surplus sludge in which activated sludge is intermittently transferred to the sludge storage tank.
Hereinafter, the present invention will be described in detail.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 and 2 are schematic diagrams showing an example of a sewage purification tank used in the present invention. In FIGS. 1 and 2, the septic tank body 1 includes a partition plate (1) 2,
The partition plate (2) 3 and the partition plate (3) 4 partition the flow control tank 5, anaerobic treatment tank 6, aerobic treatment tank 7, and sludge storage tank 8.

First, a description will be given of a mechanism of treatment by a purification tank having an aerobic treatment tank provided with a filtration membrane and a diffuser, and aerobically treating sewage with activated sludge to produce treated water.
The sewage coming out of the house flows into the flow control tank 5, is temporarily stored, and the impurities are settled and separated. Here, the flow rate adjusting tank 5 may be filled with the filter medium 9 and preliminarily filtered to remove impurities.

The sewage is transferred from the flow control tank 5 to the anaerobic treatment tank 6 by the flow control transfer device 10 by a fixed amount, is anaerobically treated by activated sludge existing in an anaerobic state, and then flows to the aerobic treatment tank 7. . As the flow rate adjusting transfer device 10, a mechanical pump such as a spiral submersible pump or a waste pump may be used, or a simple pump having a measuring device attached to an air lift pump may be used.

An air diffuser 12 is installed in the aerobic treatment tank 7, and air supplied from a blower 14 separately installed outside the septic tank main body 1 through an air supply pipe 15 is supplied to the aerobic treatment tank 7 by the aerobic treatment tank 7. Fine bubbles are ejected into the inside of the aerobic treatment tank 7 to supply oxygen into the aerobic treatment tank 7 and generate an aerated swirling flow. Thereby, the aerobic treatment is performed by the activated sludge existing in the aerobic state in the aerobic treatment tank 7.

A part of the treated water treated in the aerobic treatment tank 7 is separated into solid and liquid by a filtration membrane 13 immersed in the aerobic treatment tank 7, and only the liquid component is supplied to the outside of the tank via a filtered water pipe 17. It is to be released to. As the material of the filtration membrane, an organic or inorganic filtration membrane can be used, and the form can be a sheet-like flat membrane, a hollow fiber membrane, or the like, and is not particularly limited.

A method for extracting filtered water from the filtration membrane 13 is as follows.
The suction may be performed by a filtration pump 16 installed in the middle of the filtered water pipe 17, or the filtered water outlet at the tip of the filtered water pipe 17 may be located outside the aerobic treatment tank 7 at the position of the lowest water level LWL of the aerobic treatment tank 7. And a head pressure filtration for extruding the treated water by a head pressure generated by a water level difference from the water level of the aerobic treatment tank 7 may be employed.

In the above-described treatment method, a method may be employed in which a part of the treatment water in the aerobic treatment tank 7 is circulated and transferred to the anaerobic treatment tank 6 by the circulation device 11, and the treatment is repeated.
A method in which the anaerobic treatment tank 6 is omitted and the treatment is performed only with the flow rate adjusting tank 5 and the aerobic treatment tank 7 may be adopted, and the method is not particularly limited. Any method is acceptable. As the circulating device 11, a mechanical pump such as a spiral submersible pump or a waste pump may be used, or a simple pump in which a measuring device is added to an air lift pump may be used.

The activated sludge concentration in the treated water in the aerobic treatment tank 7 and the anaerobic treatment tank 6 is adjusted to be about several thousands to 20,000 mg / liter. The filtered water filtered by the filtration membrane 13 is sterilized by a chemical through a disinfection tank (not shown) before being discharged out of the tank.

Next, the mechanism of sludge storage will be described. In the above-mentioned septic tank, the sludge storage tank 8 is installed adjacent to the aerobic treatment tank 7 via the partition plate (3) 4. A lower opening 20 is opened in the lower part of the partition plate (3) 4,
The activated sludge settled and separated in the sludge storage tank 8 is returned to the aerobic treatment tank 7 by gravity. Here, the tank wall opposite to the partition plate (3) 4 is preferably inclined toward the aerobic treatment tank 7 so that the settled activated sludge easily returns to the aerobic treatment tank 7.

In one embodiment of the present invention, the partition plate (3) 4
Is located above the highest water level HWL of the aerobic treatment tank 7, and the treated water in the aerobic treatment tank 7 is intermittently transferred to the sludge storage tank 8 by the sludge transfer device 18. The transferred treated water is settled and separated into the activated sludge 23 and the supernatant 24 in the sludge storage tank 8. The activated sludge concentration in the aerobic treatment tank 7 is several thousand mg /
When the sludge is relatively thin, about 1 liter, the activated sludge settled and separated in the sludge storage tank 8 quickly settles out and returns to the aerobic treatment tank 7 from the lower opening 20 by gravity.
The activated sludge concentration is adjusted so as not to be too thin.
On the contrary, when the activated sludge concentration in the aerobic treatment tank 7 is relatively high, such as exceeding 10,000 mg / liter, the ratio of the volume of the solid component constituting the activated sludge to the treated water is increased. Even if it is allowed to stand still in the storage tank 8, the ratio of the activated sludge to the supernatant becomes high, and the sediment is not substantially separated. Therefore, it is adjusted so that activated sludge does not stay in the sludge storage tank 8 and the activated sludge concentration in the aerobic treatment tank 7 becomes too high.

In the above-described embodiment of the present invention, a mechanical pump such as a spiral submersible pump or a waste pump may be used as the sludge transfer device 18, or a simple air lift pump with a measuring device may be used. A suitable pump may be used. Further, in the method of intermittent operation, the transfer time and the amount of transferred water require a sufficient rest time for the transferred activated sludge to separate and separate, and the activated sludge retained in the sludge storage tank 8 is reduced. It is necessary to operate the aerobic treatment tank 7 so that it is sufficiently replaced with the treated water so that the anaerobic state does not cause rot.

In the present invention, the water level of the aerobic treatment tank and the sludge storage tank rises when the sewage flows into the aerobic treatment tank, and falls as the treated water is filtered out of the filtration membrane. It is preferable that a partition plate for partitioning between the gas treatment tank and the sludge storage tank is provided so that the treated water overflows at a position lower than the upper limit of the water level fluctuation range and higher than the lower limit. Also in such an embodiment, when processing is performed in the anaerobic processing tank 6 and the aerobic processing tank 7, the anaerobic processing tank 6 and the aerobic processing tank 7 are connected by the communication port 19 at the lower part of the partition plate (2) 3. In addition, the aerobic treatment tank 7 and the sludge storage tank 8
The lower tank 20 communicates with a partition plate (3) 4 for partitioning both tanks.

When sewage is transferred from the flow control tank 5 by the flow control transfer device 10, the water levels of the anaerobic treatment tank 6, the aerobic treatment tank 7 and the sludge storage tank 8 rise synchronously. When the filtered water is taken out by the filtration membrane 13 installed in the aerobic treatment tank 7 and discharged to the outside of the tank, the water levels of the anaerobic treatment tank 6, the aerobic treatment tank 7 and the sludge storage tank 8 fall synchronously. . When the treatment is performed only in the aerobic treatment tank 7, the water is directly transferred from the flow control tank 5 to the aerobic treatment tank 7, and the water levels of the aerobic treatment tank 7 and the sludge storage tank 8 fluctuate in synchronization.

In the above embodiment, the upper part of the partition plate (3) 4, which separates the aerobic treatment tank 7 and the sludge storage tank 8, has the treated water overflow at a position lower than the upper limit of the water level fluctuation range and higher than the lower limit. It has been made to be. The overflow may be performed by setting the upper end of the partition plate (3) 4 at a position lower than the upper limit of the water level fluctuation range and higher than the lower limit, or an upper portion opened at the upper portion of the partition plate (3) 4. The lower end 22 of the opening 21 may be lower than the upper limit of the water level fluctuation range and higher than the lower limit.

FIG. 3 shows that, in the above embodiment, sewage is transferred from the flow control tank 5 by the flow control device 10, the water level of the aerobic treatment tank 7 rises, and the upper opening 21 of the partition plate (3) 4 is closed. FIG. 4 is a schematic diagram showing a state when the water has passed over, and at this time, treated water flows from an upper opening 21 of a partition plate (3) 4 by an aerated swirling flow by a diffuser 12 installed in an aerobic treatment tank 7. 8, the treated water flows down the sludge storage tank 8 and returns from the lower opening 20 to the aerobic treatment tank 7. Therefore, the sludge staying in the sludge storage tank 8 is replaced with the treated water in the aerobic treatment tank 7.

FIG. 4 shows that in the above embodiment, the water level of the aerobic treatment tank 7 is lowered by taking out filtered water through the filtration membrane 13 installed in the aerobic treatment tank 7, and the upper opening of the partition plate (3) 4 is opened. FIG. 4 is a schematic diagram showing a state below a part 21. At this time, the sludge storage tank 8 is left still, the activated sludge in the treated water is settled, and separated into a supernatant part 24 and an activated sludge 23. When the activated sludge concentration in the aerobic treatment tank 7 is relatively low, such as several thousand mg / liter, the activated sludge settled and separated in the sludge storage tank 8 is quickly settled, and is aerobically treated from the lower opening 20 by gravity. In order to return to the tank 7, the activated sludge concentration in the aerobic treatment tank 7 is adjusted so as not to be too low. Conversely, when the activated sludge concentration in the aerobic treatment tank 7 is relatively high, such as exceeding 10,000 mg / liter, the volume of the solid component constituting the activated sludge in the treated water is increased, and the sludge is stored. Even if it is allowed to stand in a tank, the ratio of the activated sludge to the supernatant becomes high, so that the sediment is not substantially separated.
Therefore, it is adjusted so that activated sludge does not stay in the sludge storage tank 8 and the activated sludge concentration in the aerobic treatment tank 7 becomes too high.

In the above-described embodiment, the sewage discharged from homes is treated with activated sludge every day, and then filtered by the filtration membrane 13. Therefore, the sewage is transferred from the flow rate control tank 5 and rises in water level. The descending cycle will be repeated several to several tens of times a day. Water level is partition plate (3) 4
The exchange of the activated sludge retained in the sludge storage tank 8 over the upper opening 21 is completed in a relatively short time, and the water level becomes lower than the lower end 22 of the upper opening 21 so that the activated sludge 2 is replaced.
It takes a relatively long time for the precipitate 3 to separate from the supernatant 24. Therefore, it is preferable that the position of the upper opening 21 of the partition plate (3) 4 be installed as high as possible in the fluctuation range of the water level.

[0027]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Embodiment 1 An embodiment of the present invention will be described with reference to the sewage purification tank shown in FIG. The sewage purification tank 1 includes a partition plate (1) 2 and a partition plate (2).
3 and a partition plate (3) 4 are divided into a flow control tank 5, an anaerobic treatment tank 6, an aerobic treatment tank 7, and a sludge storage tank 8,
Each tank capacity 1.2m ^3, 0.4m ^3, 0.3m
³ and 0.2 m ³ .

Wastewater discharged from households averages 1.
The water was flowed into the flow control tank 5 with a water amount of 25 m ³ , and the impurities were settled and removed and temporarily stored. The sewage stored in the flow control tank 5 was transferred by the flow control transfer device 10 until the water level in the anaerobic treatment tank 6 reached the maximum water level HWL, and was anaerobically treated with activated sludge. The amount of water transferred at one time is about 1
00 liters.

The treated water subjected to the anaerobic treatment was transferred from the communication port 19 to the aerobic treatment tank 7 and aerobically treated with activated sludge.
A filtration membrane 13 was installed in the aerobic treatment tank 7, suction-filtered with a filtration pump at a flow rate of about 1 liter / min, sterilized in a disinfection tank (not shown), and discharged outside the tank. Filtration was continued until the water level in the aerobic treatment tank 7 reached the minimum water level LWL.

The water levels in the anaerobic treatment tank 6, the aerobic treatment tank 7, and the sludge storage tank 8 fluctuate in synchronization, and the fluctuation range is about 20 c.
m. A part of the treated water in the aerobic treatment tank 7
1 and circulated to the anaerobic treatment tank 6 at a water flow rate of about 2.6 liters / min. The upper opening 21 of the partition plate (3) 4 is set so that the lower end 22 of the opening is about 3 from the highest water level HWL of the water level fluctuation width.
cm.

In the above-described operation method, the flow control transfer device 10
When the water level reaches the maximum water level HWL, the effluent from the aerobic treatment tank 7 is separated by the aeration swirling flow of the aeration device 12 installed in the aerobic treatment tank 7 and the partition plate (3) 4 From the upper opening 21 into the sludge storage tank 8, descends inside the sludge storage tank 8, returns to the aerobic treatment tank 7 from the lower opening 20, and the accumulated sludge is completely replaced in the sludge storage tank 8. Thereafter, the water level was lowered by filtration, and after about 15 minutes, the lower end 22 of the upper opening 21 of the partition plate (3) 4 became higher than the water surface, so that the sludge storage tank 8 was allowed to stand still and sedimentation and separation of activated sludge started. Was done. By allowing the water to stand in the aerobic treatment tank 7 for about 85 minutes until the water level of the aerobic treatment tank 7 reaches the minimum water level LWL by filtration, a part of the settled sludge in the sludge storage tank 8 is better than the lower opening 20 of the partition plate (3) 4. It returned to the gas treatment tank 7. Filtration was continued, and when the water level reached the minimum water level LWL, the wastewater was again transferred to the anaerobic treatment tank 6 by the flow rate adjusting transfer device 10, and the above processing was repeated.

As a result of the continuous operation of the sewage purification tank 1 of the present invention for 6 months, the anaerobic treatment tank 6 and the aerobic treatment tank 7 contained activated sludge of about 10,000 mg / liter in the initial operation. The concentration could be suppressed to about 15,000 mg / liter even after 6 months, showed good fluidity, and filtration of the treated water by the filtration membrane 13 was performed without any problem. Further, the activated sludge stored in the sludge storage tank 8 did not become anaerobic over a long period of time and did not rot, so that no odor was generated.

Comparative Example 1 As a comparative example, a continuous operation was performed for 6 months under the same conditions as in the example in a sewage purification tank in which only the sludge storage tank 8 was omitted from the sewage purification tank 1 shown in FIG. As a result, in the anaerobic treatment tank and the aerobic treatment tank, the concentration of activated sludge, which was about 10,000 mg / l in the initial stage of operation, exceeded 20,000 mg / l after 6 months, and the viscosity of the activated sludge was high. The liquidity became worse. As a result, sludge adhering to the surface of the filtration membrane due to aeration by the aeration device is not uniformly removed, the effective membrane area that can be filtered is reduced, and pores of the filtration membrane are clogged, resulting in long-term treatment water treatment. Filtration cannot be continued.

[0035]

As described above, the method for storing excess sludge of the present invention has the above-mentioned configuration, and therefore, the activated sludge concentration in the treatment tank can be adjusted to an appropriate sludge concentration at low cost without using any measuring equipment. it can. In addition, since the activated sludge generated in excess and stored in the tank is not maintained in an anaerobic state for a long time, no odor is generated without rot.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one embodiment of a sewage purification tank of the present invention.

FIG. 2 is a schematic view showing a preferred embodiment of a sewage treatment tank of the present invention.

FIG. 3 In a preferred embodiment of the present invention, when filtered water is taken out by a filtration membrane installed in an aerobic treatment tank, and when the water level of the aerobic treatment tank falls and passes over the upper opening of the partition plate (3). It is a schematic diagram which shows the state of.

FIG. 4 In a preferred embodiment of the present invention, filtered water is taken out by a filtration membrane installed in the aerobic treatment tank, and the water level of the aerobic treatment tank falls and falls below the upper opening of the partition plate (3). FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Septic tank main body 2 Divider (1) 3 Divider (2) 4 Divider (3) 5 Flow control tank 6 Anaerobic treatment tank 7 Aerobic treatment tank 8 Sludge storage tank 9 Filter medium 10 Flow control transfer device 11 Circulation device 12 Dispersion Pneumatic device 13 Filtration membrane 14 Blower 15 Air supply pipe 16 Filtration pump 17 Filtration water pipe 18 Sludge transfer device 19 Communication port 20 Lower opening 21 Upper opening 22 Opening lower end 23 Activated sludge 24 Supernatant

Claims (2)

[Claims] An aerobic treatment tank having a filtration membrane and an aeration device installed therein to aerobically treat sewage with activated sludge to obtain treated water;
A method for storing excess sludge by providing a sludge storage tank adjacent to a partition plate through a partition plate, wherein the aerobic treatment tank and the sludge storage tank are communicated with each other at an opening at a lower portion of the partition plate. A method for storing excess sludge, comprising intermittently transferring activated sludge from a gas treatment tank to the sludge storage tank. 2. The water level of the aerobic treatment tank and the sludge storage tank rises when the sewage flows into the aerobic treatment tank, and falls as the treated water is filtered out of the filtration membrane. The partition plate for partitioning between a tank and the sludge storage tank is provided so that the treated water overflows at a position lower than the upper limit of the fluctuation range of the water level and higher than the lower limit. Method of storing excess sludge.