JP2003117585A - Method for biologically treating organic matter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a treatment method and a treatment equipment capable of efficiently treating organic matter including fats and oils such as waste edible oil. SOLUTION: Organic matter including fats and oils is biologically treated with a biological treatment equipment comprising mesophilic bacteria and thermophilic bacteria each having fat and oil degrading power, a porous support carrying the mesophilic bacteria and thermophilic bacteria and a tank housing the organic matter including fats and oils.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for biological treatment of organic matter containing fats and oils, and in particular to edible oils and household wastewaters discarded from general households, hotels, restaurants, buildings, lunch centers, etc. The present invention relates to a method and an apparatus for treating organic matter, which can be suitably used in all technical fields for treating organic matter such as industrial wastewater generated in food processing plants, fisheries processing plants, oil and fat industries, and sewage treatment plant wastewater. It is a thing.

[0002]

2. Description of the Related Art In recent years, in Japan, a large amount of edible waste oil is discharged from homes and restaurants due to changes in eating habits, which has a great impact on the water environment. The total consumption of edible oils and fats in Japan is about 2 million tons per year, and about 400,000 tons of edible waste oil is generated, about half of which, 200,000 tons, is spilled into domestic wastewater for public use. It is washed away in water. In addition, the amount of edible waste oil discharged from ordinary households is about 40.
It is 0 to 600 g / person / year.

Edible waste oil has an extremely high content of organic substances (organic load) per unit volume and unit weight, and in wastewater treatment facilities, generation of offensive odors, treatment of pipes, screens and control equipment by formation of scales and scum. Obstacles to function,
It causes various troubles such as sludge settling property and dewatering property deterioration.

Regarding the treatment of such organic wastes containing fats and oils, conventionally, a method has been generally used in which a coagulant is added and then an oil component is separated and recovered by a physicochemical method.
However, although the recovered oil is processed by landfilling, incineration, etc., it easily decomposes and produces a foul odor.
There were problems that it had to be processed immediately and that it was expensive to entrust processing to a specialist.

[0005] In the case of oil-and-fat-containing wastewater, it has also been treated with activated sludge. Although activated sludge has the effect of suppressing the generation of offensive odor due to the decay of accumulated oil and fat,
Insufficient fat and oil decomposition activity. That is, activated sludge is
Although it decomposes proteins, sugars, and carbohydrates well, its ability to decompose fats and oils is generally low. In order to improve the activity of decomposing fats and oils, it is necessary to lengthen the residence time in the treatment tank of the oil and fat-containing wastewater and replenish the special microorganisms in the treatment tank, resulting in high cost and operation. It becomes complicated. In addition, fats and oils form an oil film on the surface of sludge and hinder the supply of oxygen, which causes a problem that the activity of microorganisms in the activated sludge is impaired. Further, for example, it is difficult to directly treat organic waste containing fats and oils having a BOD (biochemical oxygen demand) of about 1.4 million mg / l by the conventional activated sludge method, and much labor is required. Since it is expensive, there is a problem in terms of cost, and the development of a simple and efficient processing method is desired.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a processing method and a processing apparatus capable of efficiently processing an organic substance containing fats and oils such as edible waste oil.

[0007]

Means for Solving the Problems The present invention for achieving the above object is characterized by a method for biological treatment of organic matter, which comprises treating organic matter containing fats and oils with mesophilic and thermophilic bacteria capable of degrading fats and oils. Is. At this time, it is preferable to supply water and / or air to adjust the atmosphere, or to supply nitrogen to adjust the ratio of the amount of carbon to the amount of nitrogen (C / N ratio). It is also preferable to repeatedly supply the waste containing oil and fat, nitrogen, and water in a batch manner, or to adjust the atmospheric temperature to alternate between a high temperature region and a medium temperature region.

Further, the present invention is an organism of organic matter comprising mesophilic and thermophilic bacteria capable of degrading fats and oils, a porous carrier carrying these mesophilic and thermophilic bacteria, and a tank for containing organic substances containing fats and oils. It is characterized by a processing device. Here, it is preferable to provide a supply means for supplying at least one of water, air and nitrogen.

In the present invention, the mesophilic bacterium is a bacterium having an optimum activity temperature in the range of 30 to 45 ° C., and the thermophilic bacterium is
It is a bacterium whose optimum activity temperature is in the range of 50 to 70 ° C.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The method for biological treatment of organic matter according to the present invention is carried on a porous carrier, and decomposes oil and fat components in organic matter such as edible oil with mesophilic bacterium and thermophilic bacterium capable of degrading oil and fat, It decomposes efficiently into carbon dioxide, water, ammonia, inorganic salts, etc., and is carried out, for example, in the processing apparatus shown in FIG.

The biological treatment apparatus of FIG. 1 comprises a container 1 serving as a reaction tank, a porous carrier 2 contained in the container 1, and a container 1.
A heat insulating material 3 arranged on the outer periphery of the container 1, a stirrer 4, a ventilation pump 5 for supplying air into the container 1, and the like. Container 1
Is provided with an inlet 7 commonly used for supplying organic substances, moisture and nitrogen sources, and an exhaust port 8 for discharging gas and moisture generated by decomposition of organic substances. May be provided, and in that case, one of the plurality of supply ports may be used as the exhaust port 8. Further, the inside of the container 1 is partitioned by a perforated plate 6 that exerts a rectifying action, but the perforated plate 6 is provided with a plurality of holes arranged radially or spirally.

The porous carrier 2 is required to have a large number of pores for the growth and settlement of microorganisms, and has excellent water absorption and water retention for keeping moisture and air suitable for the growth of microorganisms, and It is preferably biodegradable. Examples are wood, charcoal, bamboo chips, activated carbon, zeolite and ceramics. Among them, especially wood, charcoal and bamboo chips reuse the waste from the mountain village,
It is also preferable from the viewpoint of recycling waste. Further, wood and bamboo chips are preferable because they are easily stirred and are not easily crushed by stirring. The shape and size are preferably small and granular in order to increase the density of microorganisms. The above porous carriers may be mixed and used.

When the container 1 serving as the reaction tank is small, the surface area of the tank is larger than the internal volume, so that the loss of the amount of heat is large and the temperature of the layer of the porous carrier 2 hardly rises. Therefore, it is preferable to surround the container 1 with a heat insulating material 3 such as Styrofoam, which is easy and inexpensive to construct.

The stirrer 4 may be any as long as it can uniformly mix and stir the porous carrier 2 and the organic substance, the mesophilic bacterium and the thermophilic bacterium to be introduced. In FIG. 1, the vertical axis is shown. A structure having a horizontal axis or a circumferential movement type may be used.

As a container with such a stirrer, a small-sized container for household garbage disposal or a composting device for commercial use may be used, and a large-sized container may be used with an upright stirrer. A circular fermentation tank, a rotary kiln type fermentation tank, a multi-stage fermentation tank, or the like, whose water content can be easily adjusted, may be used.

The ventilation pump 5 is preferably one capable of continuously supplying air into the interior of the container, and is preferably one capable of supplying air at a pressure higher than the pressure loss in the layer of the porous carrier 2, for example, a general air pump, A blower or compressor may be used.

Further, in order to make the decomposition of organic substances including fats and oils more efficient, a means for supplying water or air for adjusting the water content of the layer of the porous carrier 2, a temperature adjusting means, and a nitrogen source supply amount. It is preferable to provide adjusting means. By these means, it is preferable to maintain the atmospheric conditions in the container 1 to be optimum and to maximize the activity of mesophilic and thermophilic bacteria. These means include means for measuring the temperature, oxygen concentration, water content, etc. inside the container 1, and control means for determining the air supply amount, nitrogen source supply amount, and water supply amount based on these data. It is preferable. It is also preferable to connect a filter such as activated carbon or a deodorizing device to the exhaust port 8.

Next, a procedure for treating, for example, edible waste oil (organic matter) using the biological treatment apparatus configured as described above will be described. In addition, when treating domestic wastewater, industrial wastewater generated in food processing plants, fisheries processing plants, oil and fat industries, etc., and floating residue from sewage treatment plants, edible waste oil with high calorific value is added as organic matter. Just process it.

First, a mesophilic bacterium and a thermophilic bacterium capable of decomposing oil and fat are carried on the porous carrier 2 in the container 1, and edible waste oil is introduced through the inlet 7 together with water and a nitrogen source. Thereafter, the agitator 4 agitates the mixed bacterial cells carried on the porous carrier 2, the edible waste oil, water, and the nitrogen source, and the aeration pump 5 continuously supplies air from below the container 1 to ferment while aerating. .

By such an operation, the organic matter containing oil and fat is thoroughly mixed and contacted with the bacterial cells, the bacterial cells propagate while decomposing the oil and fat components and other organic matter, and the ambient temperature rises due to the heat of fermentation. To do. As a result, the activation of the mesophilic bacterium and the thermophilic bacterium progresses, and the fat and oil is finally decomposed into carbon dioxide and water. Moisture is evaporated by the heat of fermentation.

In addition, the higher the temperature is, the faster the internal respiration rate of microbial cells such as mesophilic bacteria and thermophilic bacteria is, and the self-decomposition of microorganisms proceeds rapidly. The endogenous respiration rate of thermophilic bacteria with an optimum activity temperature of 60 ° C is 6 times or more that of the normal temperature bacteria with an optimum activity temperature of 20 ° C. As described above, since thermophilic bacteria have a high autolysis rate, the amount of surplus microorganisms generated is extremely small.

In the present invention, it is preferable that air is continuously supplied from below the container 1 by the aeration pump 5 to perform fermentation while performing aeration. This is because the layer filled with the porous carrier 2 is aerobic. This is to maintain a stable atmosphere and supply oxygen to mesophilic and thermophilic bacteria to promote metabolic activity. Then, in order to discharge water vapor generated by the heat of fermentation, carbon dioxide which is a decomposition metabolite, water, etc. to the outside, continuous and appropriate amount of aeration is required. If the air flow rate is too small, the inside of the porous carrier 2 becomes anaerobic and the fat and oil decomposition reaction subsides. On the contrary, the air flow rate becomes excessively large, heat is released and the temperature of the porous carrier 2 decreases. Corresponding to the amount of organic matter to be charged, 10 per unit volume of the porous carrier 2 is used.
It is preferable to set the ventilation rate to 0 to 300 l / m ³ / min because the aerobic and high temperature atmosphere can be sufficiently maintained.

In order to maintain the activity of microorganisms,
It is preferable to supply the organic substance and water intermittently. That is, by supplying the organic substance into the container 1, the porous carrier 2
Although the temperature of the layer rises, it is preferable to supply water because water evaporates at this time. When the amount of organic matter supplied is too large, the cells cannot be completely decomposed and accumulate inside the tank, and finally the fermentation state deteriorates. When the amount is too small, the heat of fermentation is small and the temperature of the porous carrier 2 decreases. , The activity of the bacterial cells is reduced. Therefore, considering the organic matter content, the amount of waste oil added is preferably 2 to 6 l / m ³ / d per unit volume of the layer of the porous carrier 2. Converted to organic matter load, 3-9
While the input amount is kgBOD / m ³ / d, mesophilic bacteria and thermophilic bacteria live and grow in water, but if the water content is too low, the growth rate of organisms slows down. Proliferation stops. Also, if there is too much water,
It becomes difficult for air to pass through the porous carrier, the supply of oxygen is restricted, the inside of the porous carrier becomes anaerobic, and the growth rate of aerobic organisms slows down. Usually, if the water content is maintained at 40-60%, the reaction rate is fast and the temperature can be stable. Therefore, it is desirable to replenish the evaporated water at the same time when the edible waste oil is added.

Further, in the present invention, since the mesophilic bacterium and the thermophilic bacterium are further activated to improve the fat and oil decomposition rate,
It is preferable to supply a nitrogen source and adjust the ratio of the amount of carbon in the organic matter to the amount of nitrogen (C / N ratio). Fats and oils have a structure in which one molecule of glycerin is ester-bonded with three molecules of fatty acid, most of the constituent components are carbon components, and almost no nitrogen components are contained. Mesophilic and thermophilic bacteria require nitrogen and phosphorus as nutrient elements because they grow themselves when decomposing organic matter. Therefore, in order to adjust the C / N ratio of the organic matter to be added, it is preferable to mix egg white, rice bran, etc., which are rich in nitrogen. C / N by adding nitrogen source
The ratio decreases and the reaction temperature rises, and the oil and fat decomposition rate can be improved. The C / N ratio is preferably adjusted within the range of 20-30. In addition to egg white, rice bran, etc., the C / N ratio is adjusted using food factory drainage, brewing drainage, garbage, livestock manure, human waste sludge, sewage sludge, etc., which have extremely high concentrations of nitrogen and phosphorus. Good.

In the present invention, as described above, it is preferable that the atmosphere temperature in the container 1 is adjusted to alternate between the high temperature region and the medium temperature region by supplying the organic substance, the moisture and the nitrogen source. This is because the temperature in the container 1 is 30 to 45.
Within the middle temperature range of ℃, fats and oils are actively biodegraded, and within the high temperature range of 50 to 70 ℃,
This is because it is considered that biodegradation of organic substances including fatty acids (intermediates) produced by cleavage of ester bonds when oils and fats are decomposed is actively promoted. This is because the bacterium having a high ability to assimilate fats and oils was isolated and the optimum conditions and ability for the fat and oil decomposition of the isolated strain were confirmed to show a high fat and oil decomposition rate at 30 to 45 ° C and 50 to 70 ° C. Then, it can be inferred from the fact that the fat and oil degradability decreased. Therefore, in the present invention, for example, a semi-continuous batch operation system in which the additional supply of the organic matter, the nitrogen source and the water in a batch system is repeated once every 1 to 2 days is preferable. Further, it is also preferable to use a rotary kiln type or multi-stage type device to sequentially feed the fermented organic matter in the horizontal direction or the vertical direction while newly adding and mixing the organic matter, the nitrogen source and water to the fermented matter.

[0026]

EXAMPLES <Examples 1 to 4> For Examples 1 to 4, four biological treatment apparatuses shown in FIG. 1 were used to biologically treat edible waste oil for 40 days. The container 1 of each biological treatment apparatus was made of plastic and had an effective volume of 20 L, and the container 1 was covered with a heat insulating material 3 of styrene foam.

At the start of the experiment, in a container 1 of each apparatus, about 1 L of compost as seeds of mesophilic and thermophilic bacteria capable of decomposing oil and fat and 19 L of wood chips with a particle diameter of about 1 to 3 mm were prepared.
(Porous carrier) is mixed and water is added to make the water content 50%.
The one adjusted to the above was charged. Waste oil was charged once every two days, the amount was 3.5 L / m ³ / d, and the BOD load was adjusted to 5.25 kg / m ³ / d with egg white or rice bran. The waste oil, egg white, and rice bran were supplied so that the ratio (C / N) of the carbon content and the nitrogen content became the values shown in Table 1. In Table 1, the C / N ratio of Example 1 being ∞ means that the nitrogen component was not added at all. Air was continuously supplied at an air flow rate of 100 l / m ³ / min. In addition, about 5 times a day to accelerate the reaction.
Stir for minutes. Further, at the exhaust port 7 in the upper part of the apparatus, in order to confirm the fat and oil decomposition reaction, the carbon dioxide concentration was detected using a gas detection tube.

The results are shown in Table 1.

[0029]

[Table 1]

Here, the state of biodegradation of edible waste oil is represented by the maximum reaction temperature and the fat and oil decomposition rate. The maximum reaction temperature is an average value of the maximum temperatures at which the internal temperature of the container 1 reaches a peak after each charging. In addition, the oil and fat decomposition rate was calculated by extracting the oil and fat content in the porous carrier sample using N-hexane after the end of the experiment and comparing the amount of residual oil and fat in the device with the amount of input waste oil.

From Table 1, in each of the four devices, a decomposition reaction of fats and oils occurs, the fermentation heat generated by the activation of the mesophilic bacterium and the thermophilic bacterium raises the temperature inside the container 1 from room temperature, and the reaction temperature is 39 to 55 ° C. It can be seen that it changed in the range of.

According to the exhaust gas detection result, the carbon dioxide concentration fluctuated within the range of 0.1 to 2.0%, but the carbon dioxide concentration in the atmosphere (0.035%) was always measured. It was exceeding the numerical value. From this, it was found that the edible waste oil was decomposed into carbon dioxide and water by the aerobic mesophilic bacterium and thermophilic bacterium capable of degrading fats and oils.

As shown in Table 1, the maximum reaction temperature tended to increase as the C / N ratio decreased. The decomposition rate of the fat and oil was 70% in the apparatus in which no nitrogen source was added, whereas the decomposition rate was 90% in the apparatus with the C / N ratio of 20. From this result, C / N
It was found that adjusting the ratio increased the decomposition rate of waste oil. <Example 5> A biological treatment of edible waste oil was performed using the same apparatus as in Example 1 except that a plastic container having an effective volume of 3 l was used as a reaction tank, the stirrer 4 was not provided, and styrene foam was used as a heat insulating material. Was carried out for 90 days, and long-term treatment effect and stability were confirmed.

The filling amount of the porous carrier was 2.5 l, and the stirring was performed once a day with a scoop so that the inside was sufficiently stirred. The edible waste oil is added once every two days at a rate of 5 l / m ³ / d per unit volume of the layer of the porous carrier, and BO
Rice bran was added so that the D load was 7.5 kg / m ³ / d. Air was continuously supplied at an air flow rate of 200 l / m ³ / min. Further, water was added so that the water content of the porous carrier layer was 40%.

As a result, the reaction temperature constantly fluctuated around 50 ° C., and after 90 days, the cumulative input amount of edible waste oil, rice bran and water reached 1.4 kg, but the increase amount of the layer of the porous carrier was It was only 0.3 kg. Moreover, according to the extraction and measurement result of the oil and fat content using n-hexane, the edible oil was about 97
It was found that it was efficiently decomposed with%. <Example 6> Using the same apparatus as in Example 5 except that cedar chips having a particle size of 2 to 5 mm were used as the porous carrier, organic matter obtained by adding edible waste oil to blue-green sludge was biologically treated.

The water-bloom sludge, which had grown in Kasumigaura, was coagulated using a polymer coagulant polyaluminum chloride (PAC), dehydrated, and mixed with edible waste oil. Regarding the mixing ratio, the edible waste oil was mixed at a ratio of 15% (V / V) to the water-bloom sludge having a dehydrated cake concentration of 40,000 mg / l. The dehydrated cake of dehydrated water-bloom sludge had a water content of 84%, a loss on ignition (VSS) of 75%, a C / N ratio of 4.5, a BOD of 133 mg / g, and a calorific value of 3%.
It was 470 kcal / kg-ds. The continuous air flow rate was 200 l / m ³ / min.

Looking at the time-dependent changes in the temperature and the generated carbon dioxide concentration under these conditions, the temperature rapidly rises from room temperature to 50 ° C. or higher, and then remains at around 50 ° C. for 20 to 30 hours. , Then declined. In addition, carbon dioxide is rapidly generated in the initial stage after the introduction, which means that oil and water-bloom are decomposed. As a result of calculating the carbon balance, it was found that about 80% of the organic matter in the introduced water-bloom sludge was decomposed into carbon dioxide.

[0038]

According to the present invention, an organic substance containing fats and oils is
Since the treatment is performed using a mixed bacterium containing mesophilic and thermophilic bacteria having oil-and-fat decomposing ability, the effect of decomposing organic substances is remarkable, and since microorganisms can be stably retained in the treatment equipment tank, long-term treatment is possible. Stable continuous processing is possible.
And in the present invention, food factory drainage, brewing drainage,
Even high-concentration organic wastewater such as food waste, livestock manure, human waste sludge, and sewage sludge can be efficiently decomposed by mixing with oils and fats such as edible waste oil.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a biological treatment apparatus according to an embodiment of the present invention.

[Explanation of symbols]

1 container 2 Porous carrier 3 heat insulating material 4 stirrer 5 Ventilation pump 6 Perforated plate 7 slot 8 exhaust port

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C12M 1/04 C12M 1/04 4D059 C12N 1/00 C12N 1/00 SF term (reference) 4B029 AA02 BB01 CC02 CC10 DA01 DB17 DF03 4B065 AA99X BB10 BB26 BC05 BC12 BC42 CA55 4D003 AA13 AB02 EA14 EA19 EA21 EA24 EA25 FA06 4D028 AB03 AC06 BB02 BC26 4D040 DD03 DD12 DD24 DD31 4D059 AA10 BA03 BA22 BA27 BJ01 DB31

Claims (7)

[Claims] 1. A method for biological treatment of organic matter, which comprises treating an organic matter containing fats and oils with mesophilic and thermophilic bacteria capable of degrading fats and oils. 2. The biological treatment method for organic matter according to claim 1, wherein the atmosphere is adjusted by supplying water and / or air. 3. The method for biological treatment of organic matter according to claim 1, wherein nitrogen is supplied to adjust the ratio of carbon content to nitrogen content (C / N ratio). 4. The method for biological treatment of organic matter according to claim 1, wherein the atmospheric temperature is adjusted so as to alternate between a high temperature range and an intermediate temperature range. 5. The method for biological treatment of organic matter according to claim 1, wherein waste containing oil and fat, nitrogen and water are repeatedly supplied in a batch manner. 6. An organic substance comprising a mesophilic bacterium and a thermophilic bacterium capable of degrading fats and oils, a porous carrier carrying the mesophilic bacterium and a thermophilic bacterium, and a tank for containing an organic substance containing fats and oils. Biological treatment equipment. 7. The biological treatment apparatus for organic matter according to claim 6, further comprising a supply means for supplying at least one of water, air and nitrogen.