JP4338030B2 - Anaerobic treatment of soy sauce cake - Google Patents

Description

    The present invention is an anaerobic treatment of soy sauce cake that mixes soy sauce cake with dilution water and then stores it in an air-blocked treatment tank, digests anaerobically in the presence of anaerobic bacteria, and separates the generated biogas Regarding the improvement of the method, in particular, the water-diluted slurry of soy sauce cake with very high BOD and chloride ion concentration can be processed as it is without desalting, and the slurry can be treated very efficiently with methane, hydrogen, carbon dioxide gas. , Ammonia, hydrogen sulfide or lower fatty acids can be decomposed and simplified, soy sauce cake can be almost completely decomposed (1/80 times weight), and about 300 to 450 liters of biomass can be obtained from 1 kg of soy sauce cake. In addition, a biomass having a methane concentration exceeding 50%, which can be used as a fuel gas, can be obtained continuously and stably, and a BOD of 31000 mg / l and Even with a slurry having a ruion concentration of 3900 mg / l, the BOD can be decomposed and removed by about 90% or more, and the conventional anaerobic treatment apparatus for soy sauce cake can be miniaturized and simplified. It relates to anaerobic processing of soy sauce cake.

Soy sauce cake is a residue of moromi soup (raw soy sauce) separated from soy sauce moromi in the press process of soy sauce brewing. It is used as a recycling resource, such as recycled paper and pots for gardening, but most of it is discarded or incinerated.
However, soy sauce cake contains 5-8% (W / W) of salt, and when used as it is for feed, fertilizer, etc., its use ratio must be extremely reduced.
In order to increase the use ratio of feed and fertilizer, soy sauce cake is swollen with water and left for an appropriate period of time, and the salt content in the soy sauce cake is eluted in water and pressed to make soy sauce cake (pulp content) with less salt. This must be repeated and desalted. In this case, the operation is complicated, and the standing time for eluting the salt is considerably long, so that the cost is increased and there is a problem that is not practical.
In addition, when soy sauce cake is incinerated, it has the problems of cost, energy and time for transportation to a disposal site.

Now, in the production of soy sauce oil, the organic waste liquid produced contains a large amount of various complex organic substances such as sugars, peptides and amino acids, has a high BOD, and usually reaches 15,000 to 20,000 ppm. In addition, this organic waste liquid has a high concentration of chloride or hydrochloric acid-derived chlorion (Cl ⁻ ), which is then discharged into rivers and lakes as it is to pollute the water, causing algae to grow abnormally and fish and shellfish. It is pointed out that there is a risk of killing.
Therefore, it is necessary to treat these chlorion-containing organic waste liquids at least in a state favorable for environmental hygiene. In recent years, various methods for treating organic waste liquids have been proposed as countermeasures, but it is still insufficient. hard.
In other words, sludge mainly composed of native plants and animals is put into organic waste liquid, and these organisms are ingested as a nutrient source for a part of the organic matter in the waste liquid, and part of this is absorbed using the sludge's own adsorption phenomenon. A so-called activated sludge process for adsorption is known. In addition, a biofilm of a native plant and animal is formed on the crushed stone, the waste liquid diluted on this biofilm flows down, and the organic matter in the waste liquid is ingested as a nutrient source, and a part is adsorbed to the colloid of the biofilm. Therefore, a so-called filter bed method that performs biological filtration is known. In addition, organic waste liquid is stored in a treatment tank that is shut off by air, and placed in an anaerobic environment, so that complex organic matter can be removed by anaerobic bacteria such as methane bacteria and hydrogen bacteria, methane, hydrogen, carbon dioxide, ammonia, sulfide. A so-called anaerobic treatment method is known that digests into hydrogen or lower fatty acids, etc., so that it can be safely discharged into rivers.

However, these organic waste liquid treatment methods have a low ability to assimilate organic matter of microorganisms used, and grow and propagate the aforementioned microorganisms in organic waste liquids having a high BOD and chloride ion concentration as described above. Is extremely difficult.
For example, it is known that an organic waste liquid having a BOD of 2000 ppm and a chlorine ion concentration of 1000 ppm has a BOD removal rate of only about 30% (Patent Document 1).

On the other hand, after crushing 1 part by weight of soy sauce cake, add 18 parts by weight of water and 2 parts by weight of marine sediment sludge collected from the seabed, mix well, adjust the pH to about 8 with sodium hydroxide, and then seal with a stirrer A method of fermenting anaerobically in a culture tank and reducing the amount of soy sauce cake (halved) from 1 kg of soy sauce cake to 1 g of methane, 78 g of acetic acid, 31 g of propionic acid, and 5 g of butyric acid and soy sauce cake is known. It has been. However, this method has the disadvantage that the yield of methane per unit weight of soy sauce is very bad.
In addition, after desalting organic waste containing salts, methane fermentation treatment is performed, and the post-fermentation liquid is separated into solid slurry and waste liquid by solid-liquid separation, and the solid slurry is obtained by methane fermentation. 2. Description of the Related Art A method for treating organic waste containing salts characterized by drying using a combustion gas of contained gas as a heat source is known (Patent Document 3). This method has the disadvantages that the operation of desalting treatment is complicated, the apparatus becomes large and complicated, and the cost for treating organic waste containing salts increases.
Japanese Patent Publication No.57-38320 JP 2000-262242 A JP 2002-273488 A

  The present invention can treat a water-diluted slurry of soy sauce cake having both BOD and chloro ion concentration very high without desalting, and the slurry can be treated very efficiently, such as methane, hydrogen, carbon dioxide, ammonia, It can be decomposed and simplified into hydrogen sulfide or lower fatty acids, etc., and it is possible to obtain about 300 to 450 liters of biomass from 1 kg of soy sauce cake, and continuously use biomass that has a methane concentration exceeding 50% that can be used as fuel gas. In addition, even in a slurry having a BOD of 31000 mg / l and a chloro ion concentration of 3900 mg / l, the BOD can be decomposed and removed by about 90% or more. The purpose is to provide an anaerobic treatment method for soy sauce cake with features such as miniaturization and simplification of the anaerobic treatment equipment That.

The present inventors obtained the following knowledge as a result of intensive studies to solve the above problems.
That is, soy sauce cake is diluted with an anaerobic bacteria digestion solution of the soy sauce cake, its filtrate, or slurries containing these activated sludge-containing aqueous solutions, and then stored in an air-blocked treatment tank, and in the presence of anaerobic bacteria. When anaerobically digesting with methane, the methane bacteria were stabilized, the amount of biogas generated was stably obtained, and methane per unit weight of soy sauce was obtained at a very high yield.

  Further, 1 part by weight of soy sauce cake diluted with 6 to 10 parts by weight of an aqueous liquid to form a slurry is an organic waste liquid having very high BOD and chloro ion concentrations (for example, BOD 31000 mg / l and chloro ion concentration 3900 mg). In spite of (/ l), anaerobic bacteria grew vigorously and propagated without desalting, and it was found that the organic waste liquid was suitable for sustaining the digestion reaction.

  Moreover, when the ratio of the soy sauce cake with respect to the total processing raw material was 50% (W / W) or more in terms of dry matter weight, it was found that the methane concentration in the biogas could be maintained at 50% or more.

  It has been found that when the moisture content of the treated raw material is 88 to 98% (W / W), the digestibility can be maintained at 60% or more.

  Soy sauce cake as a methane gas production raw material was found to produce about 300 to 450 liters of biogas per kg of soy sauce cake in a batch test. This was equivalent to 6 to 10 times the amount of biogas obtained from livestock manure, and was found to be about 2 to 3 times the amount of beer brewed rice. This test result is about 40 cubic rice per ton of input material (mixing ratio of soy sauce lees 10%) obtained in a continuous test at a biogas plant of Lipp Germany, about 400 cubic rice per ton of soy sauce lees It was found that the amount of biogas produced was in good agreement with the previous batch test results. Therefore, if the biogas amount can be calculated from the relationship between the amount reduced by using the counter and the time taken to return to the original position by grasping the amount of biogas generated by the counter, the digested weight of soy sauce cake can be estimated. It becomes possible to add a predetermined amount of soy sauce cake as it is corresponding to the amount of biogas generated, or add it to water and dilute it into a processing tank continuously or intermittently. I learned that soy sauce cake can be anaerobically processed.

  The present invention has been completed on the basis of these findings. That is, the present invention is a soy sauce cake, a soy sauce cake obtained by digesting the soy sauce cake with anaerobic bacteria, a filtrate thereof, or an activated sludge-containing aqueous solution thereof. In an anaerobic treatment of soy sauce cake, which is diluted and slurried and then stored in a processing tank that is shut off from air, anaerobically digested in the presence of anaerobic bacteria, and the generated biogas is separated. Is the law.

  In addition, the present invention dilutes 1 part by weight of soy sauce cake with 6 to 10 parts by weight of an aqueous liquid to form a slurry, and then stores it in a processing tank that is shut off from air, digests anaerobically in the presence of anaerobic bacteria, It is an anaerobic processing method of soy sauce cake characterized by separating biogas to be used.

  Moreover, this invention is the anaerobic processing method of the soy sauce cake as described above whose ratio of the soy sauce cake with respect to the total processing raw material is 50% (W / W) or more in terms of dry matter weight.

  Moreover, this invention is the anaerobic processing method of the soy sauce cake as described in the above-mentioned whose moisture content of a process raw material is 88 to 98% (W / W).

  In addition, the present invention is a soy sauce cake as it is or diluted with water to form a slurry, which is then stored in an air-blocked processing tank, digested anaerobically in the presence of anaerobic bacteria, and the generated biogas is separated. In addition, the digestion amount of the soy sauce cake and the biogas generation amount generated from the treatment tank are measured in advance to examine the correlation between them, and the digestion amount of the soy sauce cake is estimated from the biogas generation amount to generate biogas. An anaerobic treatment method for soy sauce cake characterized in that a predetermined amount of soy sauce cake corresponding to the amount is added as it is or diluted with water to form a slurry into the treatment tank continuously or intermittently.

  The present invention is also the anaerobic treatment method for soy sauce cake as described above, wherein the anaerobic bacteria are derived from manure of domestic animals or humans.

According to the present invention, methane bacteria can be vigorously and stably cultured, and methane per unit weight of soy sauce cake can be obtained with extremely good yield and stability.
The digested liquid of soy sauce cake is decomposed and simplified into hydrogen, carbon dioxide, ammonia, hydrogen sulfide or lower fatty acids, etc., so that it can be safely discharged into the river as it is or after water treatment if necessary. Can do.
Further, according to the present invention, it is possible to achieve a BOD removal rate of about 90% in a soy sauce cake slurry having a BOD of 31000 mg / l and a chloro ion concentration of 3900 mg / l.
In addition, according to the present invention, a high-quality gas can be stably obtained that is substantially the same as the city gas of a local city having a methane gas concentration of 50 to 60%.
In addition, the solid content obtained by solid-liquid separation from the digested liquid is a few tenths (for example, about 1/80), and it can be understood from this that the soy sauce cake can be almost completely decomposed. The decomposed product is suitable as compost, and can be used as a fertilizer for growing vegetables and garden plants in agriculture, and the separated liquid can be easily treated with water and can also be used as liquid fertilizer.
Furthermore, the biogas can remove hydrogen sulfide in the desulfurization apparatus, and then can be converted into electric power by a cogeneration type generator, and the exhaust heat from the generator can be used for heating the fermenter.
In addition, the amount of biogas generated is stable on average over the period, and the methane gas concentration can be obtained with a substantially constant concentration.
In addition, the BOD removal rate is close to 90%, and the COD removal rate is close to 50%. Therefore, there is an advantage that the subsequent water treatment is relatively easy.
Soy sauce cake has a high decomposition rate compared with cow swine manure and the like, and has a feature that the amount of solids remaining after the end of fermentation is very small.
The soy sauce koji is prepared by first mixing almost equal amounts of steamed soybeans and roasted and cracked wheat, adjusting the water content, inoculating and culturing koji mold, and making a soy sauce koji, which is mixed with a predetermined amount of saline. The soy sauce moromi is fermented and ripened to obtain aging moromi, which is obtained by squeezing and filtering. Unlike other food koji, the properties and component analysis values are very similar. Therefore, the amount of biogas produced per unit weight is almost constant, and since a closed system is used, there is almost no loss of biogas, and the digested amount of soy sauce cake can be calculated from the amount of biogas produced during fermentation. . Conversely, the amount of biogas produced can be calculated from the digested amount of soy sauce cake. Therefore, complicated operations such as sampling of the liquid during fermentation can be omitted. Moreover, the addition start time, addition amount, addition end time, fermentation end time, etc. of soy sauce cake can be easily determined. In addition, since the methane concentration during the fermentation period can be controlled within a certain range, anaerobic bacteria (methane-fermenting bacteria) can vigorously sustain methane fermentation and digest soy sauce cake in a short period of time. Become.

  The soy sauce cake may be put into a processing tank that is air-blocked as a raw material as it is, but it is more preferable that the soy sauce cake is diluted with water to form a slurry and then put into a processing tank.

Aqueous liquids used for water dilution include tap water and rivers, lake water, well water, etc., digested liquid by anaerobic bacteria in soy sauce cake, filtrate, activated sludge separated from them (collected from the bottom of the treatment tank) Of the activated sludge).
Among these, an aqueous liquid is preferable because methane fermentation by methane bacteria is vigorously and stably performed and biogas having a high methane concentration can be efficiently collected as compared with the case of using tap water and well water.
In particular, the activated sludge separated from the digestive juice was found to have a very high biogas generation capacity (fermentation power) compared to tap water.

  In water dilution, 6 to 10 parts by weight of an aqueous liquid is mixed with 1 part by weight of soy sauce cake. This is important. If the amount of the aqueous liquid is too small, anaerobic bacteria cannot vigorously propagate and digestion cannot be performed efficiently. On the other hand, if the amount is too large, the methane concentration of the biogas becomes dilute, and there is a problem that a new operation for concentrating the biogas later is required.

The processing raw material of the present invention may be soy sauce cake alone. Alternatively, the soy sauce cake may be used as a main raw material, and in addition thereto, auxiliary materials such as beer brewing coffee and okara may be added.
And it is preferable that the ratio of the soy sauce cake with respect to a total processing raw material is 50% (W / W) or more in conversion of dry matter weight. Thus, it is preferable to use 50% or more because a biogas having a high methane concentration can be obtained.

And it is preferable to adjust the moisture content of a total raw material so that the moisture content of a process raw material may be 88 to 98% (W / W) within a fermenter.
If the moisture content is too low, anaerobic bacteria cannot vigorously propagate and digestion cannot be performed efficiently. On the other hand, when the amount is too large, the methane concentration of the biogas becomes dilute, and there is a disadvantage that a new operation for concentrating the biogas is required.

  Anaerobic bacteria include bacteria that have the ability to perform anaerobic fermentation in an air-blocked processing tank. For example, cattle, pigs, and other domestic animals and humans are placed in a processing tank that is air-blocked, and anaerobic. Methane seed bacteria sludge (anaerobic bacterium) bred by maintaining the target is preferable. This anaerobic bacterium was found to have the ability to break down soy sauce cake vigorously.

The temperature of the digestion reaction is preferably 25 to 50 ° C, more preferably 35 to 45 ° C.
The digestion time is preferably 5 to 50 days, and more preferably 10 to 35 days.
In addition, digestion is preferably performed continuously or intermittently.

  In this way, after soy sauce cake is diluted with water and slurried, it is stored in an air-blocked treatment tank and digested with soy sauce cake in the presence of anaerobic bacteria accumulates biogas in the gas phase of the treatment tank. Therefore, biogas is extracted from it and used as an energy source.

In addition, when digesting soy sauce cake, it is preferable to carry out with stirring.
The stirring may be mechanical stirring or aeration stirring. Aeration and agitation is performed by penetrating the gas supply pipe through the outer peripheral wall of the processing tank and opening its tip near the bottom of the tank, and anaerobic gases such as carbon dioxide, nitrogen gas, and hydrogen gas from the other end of the gas supply pipe. It may be the one that sends in.
Hereinafter, the present invention will be described more specifically with reference to reference examples and examples.

Reference example 1
(Batch-type anaerobic treatment device for soy sauce cake using a 10-liter fermenter)
The soy sauce cake was diluted with water to form a slurry. That is, 1 part by weight of soy sauce cake and 8 parts by weight of tap water were mixed, and lightly stirred with a hand mixer to form a slurry.
A 10 liter fermenter having a capacity of 10 liters, in which the slurry is introduced from the upper opening of a bottomed cylindrical tank whose top is closed and whose bottom is closed, is hermetically sealed with a lid, and air is shut off. Obtained.
One end of the synthetic resin tube penetrated the lid and communicated with the gas phase part, and the other end communicated with the gas collection chamber. In addition, the fermenter was set in the warm water bath set to 37 degreeC, and the fermentation liquid was stirred several times a day.

Reference example 2
(Batch-type anaerobic treatment device for soy sauce cake using a 3 liter fermenter)
A batch type anaerobic treatment device for soy sauce cake was obtained in the same manner as in the anaerobic treatment device of Reference Example 1 except that the 10 liter fermenter was replaced with a 3 liter flask.
In addition, the said apparatus was set in the hot water hot water bath set to 37 degreeC, and the fermentation liquid was stirred several times a day.

Basic properties of soy sauce cake (1) Constituents The soy sauce cake used in this experiment is obtained by pulverizing strip-like soy sauce cake and sold as feed. The components of this product are shown below.
Moisture content 29.2% (W / W)
Volatile organic matter (VTS) rate 53.5%
Carbon fraction 9.6%
Ash content 7.7%

(Soy sauce lees slurry)
To 1 part by weight of soy sauce cake, 8 parts by weight of tap water was added and mixed uniformly with a hand mixer to obtain a slurry. This slurry had a pH of about 5.0 and an electric conductivity of about 12.0 mS / cm.

Breeding of methane inoculum sludge In this experiment, what was collected from the biogas plant of Silvio Co., Ltd. and that collected from the biogas plant of Sekiki Sangyo Co., Ltd. were used as the inoculum for methane fermentation. The former methane inoculum No. No. 1 was grown at a fermentation temperature of 37 ° C. based on cow manure. No. 2 is grown at 45 ° C. based on pig manure.

(Batch methane fermentation test)
(1) Observation of methane fermentation using 3 liter flask and soy sauce koji decomposition process 1 About 720 g of soy sauce cake slurry (80 g of soy sauce cake + 640 g of tap water) was added to about 2200 ml and kept in a 37 ° C. warm water bath.
Agitation was performed several times a day. When the fermentation days were about 7 days, the decrease in soy sauce cake became visible. After 33 days, some barley-derived solids contained were observed. When the supernatant portion precipitated at the bottom was collected, washed with water and dried, the amount of solid was about 1 g in a dry state.
From this, it can be seen that according to the apparatus of the present invention, methane fermentation can be efficiently performed using soy sauce cake, and the soy sauce cake can be almost completely decomposed.

(Batch methane fermentation test)
(1) Repeated methane fermentation test using 10 liter fermenter Two 10 liter fermenters were installed in a hot water bath set at 37 ° C., and the produced biogas was collected in a 20 liter polyethylene bag.
The fermentation test using the cattle manure seed sludge (Methane seed bacteria sludge No. 1) is performed at 37 ° C, and the fermentation test using the pig manure seed sludge (Methane seed bacteria sludge No. 2) is performed at 43 ° C. The tank capacity was 7 liters.
The test was repeated 9 times for the 43 ° C fermentation test and 8 times for the 37 ° C fermentation test.
The amount of biogas generated was measured.
The fermentation days were 20 days and 25 days. The amount of generated gas was converted to the amount per 1 kg of soy sauce cake.
In the above test, in order to see the influence of the salt content, the soy sauce cake obtained by diluting the soy sauce cake with 8 times water as it was, and the desalted soy sauce cake obtained by diluting with 8 times water, filtering the filter paper and drying are again used. Diluted with double water was used.
As a result, in the case of a raw material obtained by diluting soy sauce cake with water as it is, the amount of biogas produced (room temperature) was about 300 liters / kg for 43 ° C. fermentation and about 350 liters / kg for 37 ° C. fermentation. In the case where the soy sauce cake was washed once with water, the amount of gas produced was reduced by about 50 liters / kg than when it was fermented as it was.
The components of the produced biogas were analyzed at the time of the second test at 37 ° C. fermentation. As a result, 59% of methane, 35% of carbon dioxide, and 1200 ppm of hydrogen sulfide were found.

(Changes in pH and electrical conductivity due to repeated fermentation tests)
In repeating the batch-type fermentation test, an amount of digestion liquid (collected from the middle of the liquid surface and bottom surface in the fermenter) was withdrawn approximately equal to the input amount.
The electrical conductivity (the numerical value increases as the amount of ions contained) and pH (hydrogen ion index) of the extracted digestive juice were measured.
It measured about the thing of 37 degreeC fermentation. As a result, the electrical conductivity increased with the number of repetitions of the batch test, and the amount of increase was lower when the soy sauce cake was washed with water than when it was not washed.
Although the pH tends to decrease with the number of batch tests, it has been found that there is variation compared to the change in electrical conductivity.

Change in biogas generation amount with fermentation time In the fermentation test, the gas generation amount on the 20th and 25th was measured, and the change in gas generation amount with the fermentation time was examined.
As a result, the production of biogas was active up to about 10 days after the start of fermentation irrespective of the fermentation temperature. In addition, the amount of gas produced was larger when the fermentation temperature was 37 ° C. than when fermented at 43 ° C., and a difference of about 100 liters / kg was observed in the amount produced after 10 days.
Up to about 10 days of fermentation, in the case of fermentation at 37 ° C., it was observed that the sample in which the soy sauce cake was washed with water had a slightly larger gas production amount.
However, the relationship was reversed after 12 days, and the amount of gas produced after 40 days was about 370 liter / kg for the sample washed with water and about 410 liter / kg for the sample not washed.
When fermented at 43 ° C., the amount of gas produced after 40 days was about 325 liters / kg in the sample obtained by washing the soy sauce cake with water, but it was about 380 liters / kg although it was not washed.

Observation inside fermenter The situation in the fermenter after 8 times of tests at a fermentation temperature of 37 ° C. was examined.
As a result, when using a sample in which water was added to the soy sauce cake as it was and slurrying the soy sauce cake once with water, and then adding the slurry into the slurry, the fermented liquid was soy sauce. The color of the cocoon itself remained brown.
Moreover, the fermentation residue floated on the liquid level, and the amount was the same in both cases.
The situation in the fermenter in which nine tests were repeated at a fermentation temperature of 43 ° C. was examined.
As in the case of 37 ° C., the color of the fermentation broth without washing the soy sauce cake with water and the fermentation solution with the soy sauce cake washed with water were both dark brown and the residue floating on the liquid surface was blackened. This is because in the case of fermentation at 43 ° C., since the fermentation broth becomes black, such a change also occurs in the floating residue.

Reference example 3
(Continuous anaerobic treatment equipment for soy sauce cake using a large fermenter)
(1) Receiving tank The introduced soy sauce cake was put into an underground receiving tank, mixed with tap water and digested separation liquid, slurried, and adjusted to a state in which it could be put into a reactor (water content 90% or more). Methane bacteria disliked the sudden changes in contents, so the ratio of soy sauce cake was increased step by step by mixing soy sauce cake with cow dung and digested liquid.
(2) Fermenter A cylindrical tank with a diameter of 7 m and a height of 7 m, which is a hermetically sealed tank that is completely airtight, has a liquid level height of 3.1 m and a height of 7 m (reactor part volume 120 m ³ ). And a gas phase part (gas holder chamber, about 70 m ³ ).
In addition, the jacket which lets warm water flow was provided in the outer peripheral wall of the fermenter, and the liquid temperature in a fermenter was kept at 37 degreeC.
(3) Desulfurization tower (desulfurization equipment)
The biogas contains corrosive impure gas components such as hydrogen sulfide in addition to methane and carbon dioxide, which are the main components, although it is thought to depend on the concentration of the soy sauce cake to be added.
Therefore, in order to remove this corrosive component of hydrogen sulfide, about 5 to 20% of the generated gas is supplied with air, and the digestion separation liquid is circulated by a pump, thereby desulfurizing tower wall surface, upper surface and liquid. It was treated by biodesulfurization method with sulfur-oxidizing bacteria that seemed to inhabit the surface.
(4) Biogas engine generator (co-generation system)
Biogas was burned by a generator called a co-generation type, and electric power and exhaust heat energy were acquired.
In addition, the said apparatus was set in the hot water hot water bath set to 37 degreeC, and the fermentation liquid was stirred several times a day.

(Methane fermentation method using three-component mixture of soy sauce cake, cow dung, and digested liquid)
The soy sauce cake was mixed with cow dung and digested separation liquid, and methane fermentation was performed for 33 days.
The results are shown below.

(1) Raw material input amount Reactor input amount 3500 kg / day Raw material water content 93-97%
Soy sauce cake input 107.4 kg / day cattle manure input 50.5 kg / day Separation solution solids input 46.6 kg / day

(2) Biogas generation amount 90.6m ³ / day methane gas concentration 59.1%
Carbon dioxide concentration 34.4%
Period average gas generation rate 25.9m ³ / t
Biogas generation occurred stably at an average period of 90.6 m ³ / day.
The methane gas concentration was also stable at 59.1%.

(3) BOD (biochemical oxygen demand) (average)
BOD (raw material) 31000mg / l
Same (reactor) 3100mg / l
Same (digested liquid) 1700mg / l
Same (removal rate) 90%
It was found that the decomposition was performed well.

(4) COD _MN (chemical oxygen demand)
COD _MN (raw material) 27100mg / l
Same (reactor) 14700mg / l
Same (digested liquid) 12900mg / l
Same (removal rate) 46%
It was found that the decomposition was performed well.

(5) Salinity In the case of soy sauce cake, it is necessary to consider the salt content. For the fluctuation of the salinity, a numerical value obtained by converting the chloride ion concentration obtained by the silver nitrate titration method into NaCl was used.
Raw material chloride ion concentration (NaCl conversion) 3900mg / l (0.64%)
Same (reactor) (same) 2200mg / l (0.36%)
Same as above (digested solution) (same) 2100 mg / l (0.35%)

(6) From the measurement results of methane generation gas amount, methane gas concentration, and BOD above the results of the methane fermentation test, according to the apparatus of the present invention, the soy sauce cake is used as a raw material at high rate, stably, and high concentration methane biogas. It can be seen that the yield is high.

(Methane fermentation method using a mixture of soy sauce cake and digested liquid)
Subsequent to Example 1, cow soup and digested and separated liquid were continuously mixed with soy sauce cake, and methane fermentation was performed for 14 days.
The results are shown below.

(1) Raw material input amount Reactor input amount 3400 kg / day Raw material water content 94-96%
Soy sauce lees input amount 112.4kg / day cattle manure input amount 0kg / day separation liquid input amount 60.3kg / day

(2) Biogas generation 109.9m ³ / day Methane gas concentration 57.6%
Carbon dioxide concentration 31.6%
Period average gas generation rate 32m ³ / t
Biogas generation occurred stably at an average period of 109.9 m ³ / day.
The methane gas concentration was also stable at 57.6%.

(3) BOD (biochemical oxygen demand) (average)
BOD (raw material) 26000mg / l
Same (reactor) 3800mg / l
Same (digested liquid) 2700mg / l
Same (removal rate) 85%
It was found that the decomposition was performed well.

(4) COD _MN (chemical oxygen demand)
COD _MN (raw material) 23900mg / l
Same (reactor) 14300mg / l
Same (digested liquid) 14000mg / l
Same (removal rate) 40%
It was found that the decomposition was performed well.

(5) Salinity In the case of soy sauce cake, it is necessary to consider the salt content. For the fluctuation of the salinity, a numerical value obtained by converting the chloride ion concentration obtained by the silver nitrate titration method into NaCl was used.
Raw material chloride ion concentration (NaCl conversion) 3400mg / l (0.56%)
Same (reactor) (same) 2600mg / l (0.42%)
Same as above (digested solution) (same) 2400mg / l (0.39%)

(6) Results of methane fermentation test It can be seen that biogas can be stably generated even when a two-component mixed material of soy sauce cake and digested separated liquid is used. In addition, it can be seen that even if the organic content derived from cow dung decreases and the methane bacteria derived from cow dung decrease, the organic content derived from soy sauce cake increases, so that biogas increases. That is, it can be seen that soy sauce cake is used alone, and a high yield of high-concentration methane biogas can be obtained with high efficiency and stability.

(Methane fermentation with soy sauce cake and dilute water mixture)
Diluted water obtained by diluting the digested separation solution with tap water was mixed with soy sauce cake to adjust the water content to about 95%, and methane fermentation was performed for 12 days using this as a raw material.
The results are shown below.

(1) Raw material input amount Reactor input amount 3170 kg / day raw material water content 92-94%
Soy sauce cake input 226.1kg / day cattle manure input 0kg / day Separation liquid solid content input 4.2kg / day

(2) Biogas generation amount 132m ³ / day methane gas concentration 57.0%
Carbon dioxide concentration 33.9%
Period average gas generation rate 41.6m ³ / t

(3) COD _MN (chemical oxygen demand)
COD _MN (raw material) 28600mg / l
Same (reactor) 14200mg / l
Same (digested liquid) 12800mg / l
Same (removal rate) 47%
It was found that the decomposition was performed well.

(4) Salt content In the case of soy sauce cake, it is necessary to consider the salt content. For the fluctuation of the salinity, a numerical value obtained by converting the chloride ion concentration obtained by the silver nitrate titration method into NaCl was used.
Salinity (NaCl conversion) 0.71-0.84%
Same (reactor) (same) 0.5-0.65%
Same as above (digested liquid) (same) 0.58 to 0.67

(5) From the measurement results of methane generation gas amount, methane gas concentration, and BOD above the results of the methane fermentation test, according to the apparatus of the present invention, using soy sauce cake as a single raw material, with high efficiency and stability, It can be seen that high yields of high-concentration methane biogas are obtained.

(Methane fermentation using soy sauce cake and tap water mixed raw materials)
The soy sauce cake was diluted with tap water and adjusted to a moisture content of 90%, followed by methane fermentation for 10 days.
The results are shown below.

(1) Raw material input amount Reactor input amount 3270 kg / day raw material water content 89-92%
Soy sauce cake input 324.8 kg / day cow dung input 0 kg / day Separation liquid solids input 0 kg / day

(2) Biogas generation 131m ³ / day methane gas concentration 53.1%
Carbon dioxide concentration 36.4%
Period average gas generation rate 40.1m ³ / t
Biogas generation occurred stably at an average of 131 m ³ / day.
The methane gas concentration was also stable at 53.1%.

(3) COD _MN (chemical oxygen demand)
COD (raw material) 35900mg / l
Same (reactor) 13700mg / l
Same (digested liquid) 12600mg / l
Same (removal rate) 62%
It was found that the decomposition was performed well.

(4) Salt content In the case of soy sauce cake, it is necessary to consider the salt content. For the fluctuation of the salinity, a numerical value obtained by converting the chloride ion concentration obtained by the silver nitrate titration method into NaCl was used.
Salinity (raw material) (NaCl equivalent) 0.71-0.88%
Same (reactor) (same) 0.58 to 0.72%
Same as above (digested liquid) (same) 0.52 to 0.71%

(5) Results of methane fermentation test From the above measurement results of methane generation gas amount, methane gas concentration, and BOD, according to the apparatus of the present invention, soy sauce cake is used as a single raw material, and it is highly efficient, stable, and high. It can be seen that a high yield of concentrated methane biogas is obtained.

(6) The water content of the receiving tank, the water content of the reactor, and the digestibility were analyzed.
The results are shown in Table 1.
The digestibility is the rate at which the organic content in the input sludge decreases due to gasification and liquefaction, and was calculated by the following formula.
Digestibility (%) = [1-A / B] × 100
However, A = inorganic content of input sludge (%) x organic content of digested sludge (%)
B = Organic content of input sludge (%) x Inorganic content of digested sludge (%)

Table 1
Receiving tank moisture content (%) Reactor moisture content (%) Digestion rate (%)
96.8 96.5 71
95 96.7 50
95.7 96.0 87
94.0 97.3 64
94.8 97.3 69
93.5 96.9 68
93.4 96.7 78
90.7 97.9 87
92.0 95.5 62
90.4 96.9 71
91.8 96.3 71
(Average 70.7)
The average digestibility is 70.7, indicating that the degradation has progressed well.

(7) The volatile organic acid was analyzed and its concentration was measured.
As a result, when the volatile organic acid concentration is usually 300 to 500 mg / l and exceeds 2000 mg / l, it is said that the activity of methane bacteria is dulled and the digestion is affected.
However, in the present invention, the volatile organic acid concentration is in the range of 130 to 810 mg / l, and it is considered that there is no fermentation failure due to acid accumulation.

(8) Co-generation system biogas engine generator Premi22
・ Rated power output 22kw
・ Total energy conversion efficiency: 87.2%
・ Power generation efficiency: 28.2%
-Waste heat recovery efficiency 58.2%
・ Noise 65dBa / 10M
・ Vibration Ultra-low vibration type

(9) Operation time and power consumption of biogas engine generators We investigated the power generation capability when all biogas generation in February and March was generated by biogas engine generators. The results are shown in Table 2.

Table 2
Biogas Amount generated per day Power consumption
Generation amount (m ³ ) (m ³ / day) (kwh / month)
February 2431 86.8 4452.8
Mar 3039 98.0 512.3
The electric power that can be generated was 4552.8 kwh in February and 512.3 kwh in March.

In the present invention, methane bacteria can be vigorously and stably cultured, and methane per unit weight of soy sauce cake can be obtained with extremely good yield and stability.
The digested liquid of soy sauce cake is decomposed and simplified into hydrogen, carbon dioxide, ammonia, hydrogen sulfide or lower fatty acids, so that it can be safely discharged into the river as it is or after water treatment if necessary. be able to.
Further, according to the present invention, it is possible to achieve a BOD removal rate of about 90% in a soy sauce cake slurry having a BOD of 31000 mg / l and a chloro ion concentration of 3900 mg / l.
In addition, according to the present invention, a high-quality gas can be stably obtained that is substantially the same as the city gas of a local city having a methane gas concentration of 50 to 60%.
In addition, the solid content obtained by solid-liquid separation from the digested liquid is suitable as compost, and can be used as a fertilizer for growing vegetables and horticultural plants in agriculture, and the separated liquid can be easily treated with water. It has the feature that can be used as.
Furthermore, the biogas can remove hydrogen sulfide in the desulfurization apparatus, and then can be converted into electric power by a cogeneration type generator, and the exhaust heat from the generator can be used for heating the fermenter.
In addition, the amount of biogas generated is stable on average over the period, and the methane gas concentration can be obtained with a substantially constant concentration.
In addition, the BOD removal rate is close to 90%, and the COD removal rate is close to 50%. Therefore, there is an advantage that the subsequent water treatment is relatively easy.
Soy sauce cake has a high decomposition rate compared with cow swine manure and the like, and has a feature that the amount of solids remaining after the end of fermentation is very small.
Soy sauce cake has almost constant biogas production per unit weight, and since it uses a closed system, there is almost no loss of biogas, and the digestion amount of soy sauce cake is determined from the amount of biogas produced during fermentation. Can be calculated. Conversely, the amount of biogas produced can be calculated from the digested amount of soy sauce cake. Therefore, complicated operations such as sampling of the liquid during fermentation can be omitted. Moreover, the addition start time, addition amount, addition end time, fermentation end time, etc. of soy sauce cake can be easily determined. In addition, since the methane concentration during the fermentation period can be controlled within a certain range, anaerobic bacteria (methane-fermenting bacteria) can vigorously sustain methane fermentation and digest soy sauce cake in a short period of time. Become.
Furthermore, it is possible to obtain about 300 to 450 liters of biogas from 1 kg of soy sauce cake. This is equivalent to 6 to 10 times the amount of biogas obtained from livestock manure, and is about 2 to 3 times the amount of beer brewed rice. The biogas produced has a methane concentration exceeding 50% and can be used as fuel gas as it is.
From the above, the present invention opens the way for utilizing soy sauce cake as an effective resource of fuel gas as a measure for disposal of soy sauce cake.

Claims (6)

  The soy sauce cake is diluted with an digested solution of anaerobic bacteria of the soy sauce cake, its filtrate, or an aqueous solution containing these activated sludges, and then stored in an air-blocked processing tank, and in the presence of anaerobic bacteria. An anaerobic treatment method for soy sauce koji that digests anaerobically and separates the generated biogas.   After diluting 1 part by weight of soy sauce cake with 6 to 10 parts by weight of aqueous liquid and slurrying it, it is stored in an air-blocked processing tank, digested anaerobically in the presence of anaerobic bacteria, and the generated biogas is separated. An anaerobic treatment method for soy sauce koji, characterized by   The method of anaerobic treatment of soy sauce cake according to claim 1 or 2, wherein the ratio of the soy sauce cake to the total processing raw material is 50% (W / W) or more in terms of dry matter weight.   The moisture content of a processing raw material is 88 to 98% (W / W), The anaerobic processing method of the soy sauce cake in any one of Claims 1-3.   The soy sauce cake is left as it is or diluted with water to form a slurry, which is then stored in an air-blocked processing tank, anaerobically digested in the presence of anaerobic bacteria, and the generated biogas is separated. The amount of digestion and the amount of biogas generated are measured to examine the correlation between them, the amount of digestion of the soy sauce cake is estimated from the amount of biogas generated, the predetermined amount of soy sauce cake corresponding to the amount of biogas generated, Or the anaerobic processing method of the soy sauce cake characterized by adding the thing diluted with water and slurrying to a processing tank continuously or intermittently. The method for anaerobic treatment of soy sauce cake according to any one of claims 1 to 5, wherein the anaerobic bacteria are derived from manure of domestic animals or humans.