JP2002119992A - Sewage treatment method by covering surface of water of anaerobic tank with sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently reducing highly concentrated organic sludge such as excretions, or the like, generated from a barn under an anaerobic atmosphere at a low cost. SOLUTION: The surface of the water of an anaerobic tank storing sewage is covered with an air impermeable sheet to hold the upper layer water area under the sheet to an anaerobic state to adjust the whole of sewage in the tank to an environment suitable for anaerobic microorganisms. By this constitution, the decomposition of sludge by the anaerobic microorganisms is performed highly efficiently and the decomposition gas of sludge by the microorganisms generated under the sheet is discharged or recovered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for efficiently reducing the amount of sludge in high-concentration organic sewage such as manure generated from a house or a livestock barn under an anaerobic atmosphere.

[0002]

2. Description of the Related Art Conventionally, methods of treating wastewater by microorganisms include aeration (aerobic) treatment by aeration, anaerobic treatment in an anaerobic atmosphere without aeration, and a combination of aeration treatment and anaerobic treatment. The method has been done. Usually, the BOD concentration of sewage is 5,000 to 7,
If the concentration is less than 000 ppm, it can be dealt with only by aeration treatment with aerobic microorganisms such as bacteria (activated sludge treatment method). However, if the concentration is higher than this, the decomposition efficiency becomes poor and the treatment becomes difficult. Therefore, an anaerobic atmosphere is used to perform treatment with anaerobic microorganisms such as organic matter-decomposing bacteria. Then, in order to further increase the processing efficiency, an aeration process is often performed after the anaerobic process.

[0003] In addition, for manure and the like generated from cattle and having a very high BOD concentration (20,000 ppm or more), the method of treatment with the above microorganisms takes too much time, and therefore, a method not relying on microorganisms is often used in combination. As the method, a method is used in which a solid (feces) and a liquid (urine) are separated from feces and urine by a filtration screen, and the liquid mainly passing through the urine is further diluted by adding water to be treated (A). method)
And a method of separating a solid content and a liquid content with a coagulant (B
Method) has been performed.

In the above method A, feces and urine are separated by a screen, and about 50% of the amount of treated water is added to the generated treated water to dilute the BOD concentration to about 1500 ppm, followed by further aeration treatment. Method, which has the disadvantage of requiring a large amount of stable water.

[0005] In the above-mentioned B method, feces and urine are separated by a screw press while the feces and urine are mixed, and the separated urine has a high BOD concentration of about 15000 ppm. The separated solid content is further separated to reduce the BOD concentration to about 5,000 to 7000 p.
pm or less, and then the treated wastewater is further aerated. The cost of the flocculant used for this is, for example,
Referring to the tent of 000 cattle, it costs about 500,000 yen per month, and this burden is extremely large. In addition, when the amount of the coagulant added is large, the pH value becomes close to 9, and in that case, it is necessary to add a pH adjuster, which further increases the maintenance cost.

[0006] Although this B system is widely used, the facility for implementing it must be equipped with a large-scale device such as a screw press or a screen device, and the device also requires maintenance after installation. In essence, the labor and cost placed a heavy burden on pig farmers. And feces that are separated and removed (organic solids)
The method of disposal is preferably fertilization and reuse, but feces containing flocculants may be unsuitable for use as compost due to their medicinal properties. And such separated solids that cannot be reused also incur disposal costs such as incineration.

[0007] In both of the above AB systems, high equipment costs are required, the location of the processing facility requires a large area, and running costs such as electricity and chemicals are large. It was a matter of life and death for the pig farming business. For this reason, some companies use a violent treatment method in which only a large amount of water is used to reduce the concentration to the emission regulation value in order to reduce costs.

[0008] In the treatment of human waste generated from condominiums, apartments, restaurants, pachinko parlors, office buildings, etc., 50 to 500 persons are required to separate suspended matters in sewage and simultaneously store the separated scum and sediment. The sedimentation separation system provided with the sedimentation separation tank is adopted. In the sedimentation separation method, since the manure is diluted with water, the BOD concentration is 500 pp.
m, but the larger the scale, the worse the odor becomes,
High maintenance costs due to having to pump several times a year. Further, when the scale becomes 500 people, the size of the sedimentation separation tank becomes about 180 m ³ , and it is difficult to separate and extract the scum and sludge generated therefrom, and the pumping cost is large.

[0009]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above circumstances, and has been proposed to efficiently reduce high-concentration organic sludge such as manure generated from a house or a livestock barn at low cost under an anaerobic atmosphere. Provide a way to

[0010]

In order to solve the above problems, the present invention is to cover the water surface of an anaerobic tank containing sewage with an impermeable sheet and to maintain an upper water area under the sheet in an anaerobic state. In order to treat sludge decomposed by anaerobic microorganisms with high efficiency by adjusting the entire sewage in the tank to an appropriate environment for anaerobic microorganisms, and to release sludge decomposition gas by microorganisms generated under the sheet into the atmosphere Or an anaerobic tank water surface covering sewage treatment method using a sheet characterized by being recovered.

[0011] In the above structure, a microorganism-activating agent is added to the sewage in the anaerobic tank to promote the decomposition of sludge.

Further, in the above configuration, a supernatant obtained in an aeration tank is used as the microorganism active material.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

According to the present invention, as shown in FIG. 1, the water surface of an anaerobic tank 1 containing sewage is covered with an impermeable sheet 2 for blocking oxygen, and the upper water area of the sewage below the impermeable sheet is made anaerobic. Hold. Then, the entire sewage flowing in the tank is adjusted to an appropriate environment for anaerobic microorganisms, and the decomposition of sludge by anaerobic microorganisms is enhanced.

The transfer tube is covered with a cap to prevent air from entering. Further, by covering with this cap, emission of offensive odor can be prevented. In addition, impermeable sheet 2
Release or recover the sludge decomposed gas from the microorganisms generated below into the atmosphere.

[0016] In addition, a microbial active material such as a microbial active nutrient powder or a microbial active nutrient solution can be introduced into the sewage of the anaerobic tank to promote the decomposition of sludge.

Further, as the above-mentioned microorganism active material, a supernatant obtained in an aeration tank can be used. The supernatant contains abundant nutrients and contains enzymes that catalyze sludge degradation. In a combined anaerobic and aerobic facility, the supernatant is obtained in the same treatment facility. Therefore, there is an advantage that it can be easily and abundantly supplied and used.

[0018]

[Function] As shown in Fig. 2, the conventional anaerobic tank suppresses the activity of anaerobic bacteria in the upper part of the sewage due to the presence of oxygen in the water surface of the sewage. Further, so-called "scum" in which the surface is dried to form a thick layer has occurred. Since the amount of the gas increased with time, it had to be removed many times to secure the capacity and passage of the tank.

In the present invention, as shown in FIG. 1, the water surface of an anaerobic tank 1 containing sewage is covered with an impermeable sheet 2, so that a sewage portion F in the anaerobic tank 1 has a space above it. The oxygen in the portion S is not supplied. In addition, by covering the water surface with the air-impermeable sheet 2, the water is prevented from evaporating from the water surface, preventing the evaporative cooling of the sewage, and the heat insulating effect provided by the sheet material produces a heat retaining effect. Sewage provides a suitable temperature environment for activating anaerobic bacteria. For this reason, microorganisms that prefer an anaerobic atmosphere under the air-impermeable sheet 2 actively proliferate, and sludge components are rapidly decomposed.
Then, since there is no air contact surface on this water surface, no dregs can be generated at all with the conventional anaerobic tank.

Under the sheet 2, gas emitting odors such as methane and hydrogen sulfide generated by the activity of anaerobic bacteria accumulates, and the sheet in that portion expands as the volume of the gas expands, and the surrounding area eventually becomes large. Is released into the atmosphere through the gap. Note that generated gas such as methane and hydrogen sulfide is a useful resource that can be used as fuel and the like, and can be actively collected. For example, the suction port of the gas recovery pipe may be exposed under the impermeable sheet 2 so that the gas can be recovered in a container such as a tank.

The anaerobic tank is classified into a basin type in which the ground is dug and a tank type in which it is buried underground. In the basin type, a sheet may be placed thereon, and as shown in FIG. It is preferable to provide a sheet roof 3 or the like so as to cover the reservoir. In the water tank system, a method in which a bag-like sheet is incorporated in the tank and the bag is expanded and contracted in accordance with a change in the amount of water is possible.

[0022]

[Experimental Example 1] An experiment was conducted in an existing outdoor treatment facility at a pig farm. This pig farm breeds about 1000 pigs, and as shown in FIG. 3, 8 ponds (1000 m ³ ×
8 = 8000 m ³ ) and five aeration layers 4 (70 m ^{3 in} total). This pig farm averages 4.5m ³
Manure per day. First, it was as follows when the manure flowing into the existing facility was examined.

<Inflowing manure> BOD 21500 mg / l CODMn 7780 mg / l SS 2350 mg / l

The inspection results of sewage flowing into the aeration layer 4 from the last eighth pond were as follows.

<Sewage flowing into the aeration layer> BOD 6800 mg / l CODMn 3900 mg / l SS 340 mg / l

Next, at that facility, an experiment was conducted in which all eight ponds were covered with a vinyl sheet 2. And as a result, the anaerobic tank 1 so far under the vinyl sheet 2
There was no dregs at all. In addition, as a result of covering with the sheet, unsightly appearance was eliminated, and particularly, offensive odor was eliminated. Conventionally, it took about 6 months to process BOD to about 7300 ppm in this facility, but in this experiment, it was possible to process to about the same BOD value in about 2 months. In other words, the processing can be performed in a shorter time of 1/3 than before, which means that the processing tank can be processed with a volume of 1/3.

Further, when the supernatant liquid formed in the final aeration layer 4 was put into eight ponds by the return pipe 5, it was possible to treat the BOD value to about the same level as the conventional case in about one month. This means that processing can be performed in a shorter time of 1/6 than before, which means that the volume of the processing tank can be greatly reduced to 1/6. Represents.

Further, when a microbial activator such as a liquid, powder or pellet-form microbial active nutrient is put into the wastewater, the decomposition of the sludge is promoted as in the case of the above-mentioned supernatant, and the large amount of the sludge is promoted. A processing effect was obtained. The microbial active materials used for this are Zero One (trade name of Prio Co., Ltd.),
Zeroto (trade name of Prio Co., Ltd.), etc., and at present, various compounds such as organic substances and inorganic substances are provided, and commercially available ones can be used.

[0029]

[Experimental Example 2] An experiment was conducted at an existing underground treatment facility at Restaurant B. This B restaurant has an underground storage facility for about 100 people. And the BOD concentration of the sewage in this tank was about 500 ppm. Here, a method is adopted in which sewage is pumped out regularly (once a month) before it becomes full. The odor was very bad, the amount of waste was not reduced, and it took about one million yen a year to pump the sludge.

At the facility, as shown in FIG. 1, an experiment was conducted by covering the entire surface of the water with a vinyl sheet 2 and covering the transfer pipe with a cap 6 to prevent air from entering. as a result,
Under the vinyl sheet 2, no humming of the conventional anaerobic tank 1 occurred, and the odor was eliminated. When the inspection is performed one month later with the vinyl sheet 2 covered, the sludge is decomposed and the BOD concentration is about 500 ppm before the vinyl sheet 2 is covered.
pm. The amount of settled sludge in the tank also decreased.

[0031]

The present invention is as described above. As shown in the above experimental results, the anaerobic tank 1 is covered with an air-impermeable sheet 2 for blocking oxygen from entering from the water surface. The supply of oxygen under the sheet is cut off, the growth of anaerobic microorganisms in the upper part of the sewage in the anaerobic tank 1 and the decomposition of sludge are promoted, and the treatment efficiency of sludge can be greatly improved. became.

Since there was no air contact with the water surface in the anaerobic tank 1, no fogging, which had been associated with the conventional anaerobic tank, could be generated, and the odor could be eliminated.

In addition, since the water is efficiently treated, the water intake for reducing the concentration, which has been performed so far, is not required, and the electricity cost for operating the equipment can be saved. In addition, the amount of excess sludge settled and separated is greatly reduced, and there is no addition of a coagulant. Therefore, composting of the excess sludge can be actively promoted, and the burden of final treatment of discharged materials is greatly increased. Can be improved.

[0034] In the case of human waste treatment in dwellings such as condominiums, so far it has been necessary to pump several times a year, but in the present invention, the amount of settled sludge is greatly reduced. Once every few years, maintenance costs can be greatly reduced. Furthermore, for the management of the livestock industry, there is a significant advantage that the cost associated with the treatment of manure can be significantly reduced and the management of the livestock industry can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of the present invention, and FIG.

FIG. 2 is a plan view schematically showing a conventional method (A) and (B).
Is a longitudinal side view.

FIGS. 3A and 3B are schematic plan views of the experimental facility, and FIGS.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anaerobic tank 2 Impermeable sheet 3 Roof 4 Aeration tank 5 Return pipe 6 Cap F Waste water part in S S Space part in S

Claims (3)

[Claims] 1. An anaerobic tank filled with sewage is covered with an impermeable sheet to maintain an upper anaerobic area under the sheet in an anaerobic state, so that the entire sewage in the tank is adjusted to an appropriate environment for anaerobic microorganisms. An anaerobic tank water-surface-covered sewage treatment using sheets, which efficiently treats decomposition of sludge by anaerobic microorganisms and releases or collects sludge decomposition gas generated by microorganisms under the sheet into the atmosphere. Law. 2. The anaerobic tank water surface covering sewage treatment method according to claim 1, wherein a microbial activator is introduced into the anaerobic tank sewage to promote the decomposition of sludge. 3. The method according to claim 2, wherein the microbial activator is a supernatant obtained in an aeration tank.