KR20140112292A - Hydrogen production from dark fermentation of high-protein material under anaerobic condition - Google Patents

Abstract

Provided is a hydrogen production method by anaerobic dark fermentation of high protein waste which is characterized by comprising the steps of: heat treating anaerobic digester sludge; manufacturing a mixed solution of the heat treated anaerobic digester sludge and high protein waste; and culturing the manufactured mixed solution in a dark place for anaerobic dark fermentation. The mixing ratio of the mixed solution has F/M ratio of 6 and pH of 8.2 and agitation culturing at 48~52 °C for an optimum hydrogen production method. According to the present invention, hydrogen can be produced in high efficiency by anaerobic dark fermentation of high protein wastes conventionally known as not having high hydrogen production efficiency.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing hydrogen from high-molecular-weight waste by anaerobic fermentation,

The present invention relates to a method for producing hydrogen using bio waste, and more particularly, to a method for producing hydrogen using anaerobic fermentation of high-protein waste. More particularly, the present invention relates to a method for efficiently producing hydrogen by mixing high-protein waste with a heat-treated anaerobic digester sludge and fermenting the anaerobic digester.

Hydrogen production through dark fermentation is the process of converting organics into hydrogen by fermentation using bacteria. This cancer fermentation process is a collection of complicated biochemical reactions involving various groups of bacteria. Bacteria such as the Clostridium genus are known to exhibit high hydrogen production rates during fermentation of anaerobic cancers.

Dark fermentation under anaerobic condition means cancer fermentation in anaerobic condition. The process of fermentation of anaerobic cancers consists of the steps of ① hydrolyzing organic polymers that are not soluble in bacteria and finely dividing them into molecules that can be used by other microorganisms, ② separating the saccharide and amino acids with substances such as carbon dioxide, hydrogen, ammonia and organic acids Converting the remaining organic acids of acetic acid-producing bacteria into acetic acid, ammonia, hydrogen, carbon dioxide and the like; and (4) converting the above products into methane and carbon dioxide.

Hydrogen is more environmentally friendly than fossil fuels, and it is attracting attention as a future energy source. However, about 95% of the world's hydrogen production is made by steam reforming of natural gas, partial oxidation of heavy oil, and gasification of coal. Unlike previous methods, biologically producing hydrogen through biodegradation or cancer fermentation has been studied. Among them, cancer fermentation is generally known to be the most cost effective method because it has a small environmental impact and a high rate of energy conversion.

In terms of environment, hydrogen production using abundant and inexpensive organic wastes such as food wastes, agricultural and livestock wastes is an important research topic in the field of bioenergy. Biological hydrogen production through organic fermentation of organic wastes has attracted considerable attention in recent years, and it has attracted considerable attention for many years, including hydrogen production method in a low hydrogen partial pressure environment, hydrogen production method in an environment in which carbon dioxide is removed, And a method for increasing the efficiency of hydrogen production using organic wastes.

However, the problem of hydrogen production using organic fermentation of organic wastes varies greatly depending on the composition of carbohydrate, protein and lipid composition of wastes. In particular, since the substrate (hereinafter, referred to as 'high protein substrate') having a protein as a main constituent has a very low hydrogen production efficiency as compared with a substrate having a carbohydrate as a main constituent (hereinafter referred to as 'high carbohydrate substrate'), The general view is that it is not easy to use as raw material for hydrogen production. Most of the studies on hydrogen production through cancer fermentation have been carried out using pure carbohydrates or high carbohydrate substrates such as glucose, sucrose, fibrin, and starch as raw materials, and only a few studies using high-protein substrates have been conducted. It has also failed to achieve a high hydrogen production rate by using wastes (hereinafter referred to as "high-protein waste") containing protein as a main constituent.

The results of hydrogen production using high-protein substrates are as follows. Using high-carbohydrate rice, the high hydrogen production rate of 96 ml H ₂ / g-VS was shown, but in the case of the high-protein egg, the hydrogen production rate was much lower than that of 7.1 ml H ₂ / g-VS (M. Okamoto, T. Miyahara, O. Mizuno, T. Noike, Water Sci . Technol ., 2000, 41 (3): 25). In addition, high carbohydrate substrates such as rice and potato showed 20 times higher hydrogen production potential than high protein substrates such as eggs and boiled meats (J.-J. Lay, K.-S. Fan, J.-l Chang, C.-H. Ku, Int . J. Hydrogen Energy , 2003, 28: 1361). Some studies have concluded that the substrate of major hydrogen production is carbohydrate, and that the role of protein is only the regulation of pH through the production of nitrogen source and ammonia for cell growth (MD Bai, SS Cheng, YC Chao, Water Sci . Technol . , ≪ / RTI > 2004, 50: 209-216). Similarly, the use of rice yielded a hydrogen production rate of 134 ml H ₂ / g-VS, but a study also showed that hydrogen production did not occur when boiled meat was used (L. Dong, Y. Zhenhong, S Yongming, K. Xiaoying, Z. Yu., Int . J. Hydrogen Energy ., 2009, 34: 812-820).

Although it was a general result that the hydrogen production rate was very low when using the high protein substrate as above, the present inventors discovered a method of obtaining a high hydrogen production rate by using high-protein waste, beyond the conventional skeptic results, and completed the present invention. The summary of the present invention is that when anaerobic digestion tank sludge is mixed with high-protein waste and high-protein waste mixed with the anaerobic digester sludge is cultivated in a dark place, the anaerobic digestion sludge and high- The hydrogen production is greatly increased under certain conditions depending on the mixing ratio of water, the change of the pH value, the shaking in the culture, and the presence of carbon dioxide in the head space.

- M. Okamoto, T. Miyahara, O. Mizuno, T. Noike, Water Sci. Technol., 2000, 41 (3): 25 - J.-J. Lay, K.-S. Fan, J.-l Chang, C.-H. Ku, Int. J. Hydrogen Energy, 2003, 28: 1361 - M. D. Bai, S. S. Cheng, Y. C. Chao, Water Sci. Technol., ≪ / RTI > 2004, 50: 209-216 - L. Dong, Y. Zhenhong, S. Yongming, K. Xiaoying, Z. Yu., Int. J. Hydrogen Energy., 2009, 34: 812-820

It is an object of the present invention to provide a method for increasing hydrogen production in the case of producing hydrogen by using anaerobic membrane fermentation of high-protein waste.

To achieve the above object, the present invention provides a method for treating anaerobic digestion sludge, comprising the steps of: Preparing a mixture of the heat-treated anaerobic digester sludge and high-protein waste; And fermenting the anaerobic cancer by culturing the mixed solution in a dark place.

Methanogen produces methane using hydrogen. Therefore, it is necessary to prevent the methane production process of methanogenic bacteria when anaerobic fermentation of waste is carried out using bacteria contained in anaerobic digester sludge. The heat treatment process is performed to remove the methanogenic bacteria that do not form spores, thereby suppressing the methanogenesis process.

The step of heat-treating the anaerobic digester sludge is preferably performed by incubating the anaerobic digester sludge at 40 to 60 ° C for 24 to 72 hours and then heating at 90 to 110 ° C for 1 to 2 hours. The reason why the anaerobic digester sludge is first cultivated at 40 ° C to 60 ° C is that the thermophilic bacteria in the anaerobic digester sludge are activated within the fermentation temperature range and the organic matter present in the anaerobic digester sludge is self- biogas) that can occur in the future. The reason for heating at 90 to 110 ° C is to remove methanogenic bacteria that do not form spores. If the heating in this heat treatment step is performed for 2 hours or more, there is a disadvantage that the activity of bacteria performing anaerobic cancer fermentation is lowered. However, the method of heat treatment is not limited thereto, and any method of heat treatment that can remove the methanogenic bacteria that do not form spores can be used.

High-protein waste refers to wastes with protein as a major constituent. At this time, the waste is often high-protein food waste including high-protein meat, but if it is high-protein waste, not only food waste but also any waste such as sewage waste, agricultural waste, livestock waste,

Therefore, the high-protein waste can be selected from high-protein food waste, high-protein sewage waste, high-protein agricultural waste, high-protein animal wastes, and high-protein industrial wastes.

Food to Mass ratio refers to the ratio of food to microorganism and more specifically to volatile solids (VS) present in anaerobic digester sludge, volatile solids ≪ / RTI >

The mixing ratio of the heat-treated anaerobic digester sludge to the high-protein waste mixture is preferably in the range of 4 to 9 in F / M ratio. When the F / M ratio is lower than this range, it becomes difficult to control the methanogenic bacteria. If the F / M ratio is higher than the above range, the pH of the mixed solution may be drastically lowered to affect the fermentation. Also, the condition of F / M ratio of 6 is most effective for increasing hydrogen production.

The pH of the mixed liquor is very important for hydrogen production because it affects the activity of hydrogen production enzymes and the metabolic pathway of bacteria. A mixed solution having a pH above or below the optimum range inhibits the activity of a hydrogen producing bacterium, and thus is not a suitable method for producing hydrogen.

The step of fermenting anaerobic cancer with the prepared mixed solution may be performed under the condition that the pH of the mixed solution is maintained at 7.0 to 9.0. Environments other than these optimal conditions may inhibit the activity of hydrogen producing bacteria. Also, it is most effective to increase the hydrogen production by performing the operation under the condition that the pH of the mixed solution is maintained at 8.2.

The fermentation temperature is a very important factor affecting the growth rate and metabolic activity of bacteria. The fermentation temperature can be divided into mesophilic (25 ~ 40 ℃), thermophilic (40 ~ 60 ℃) and extreme thermophilic (60 ~ 80 ℃). In order to produce hydrogen using thermophilic bacteria, the incubation temperature should be maintained in a humid environment. Hydrogen - producing bacteria contained in anaerobic digester sludge used as an inoculum are known to be hot. In addition, pre - heating anaerobic digestion sludge was first cultured at 40 ~ 60 ℃ to promote the growth of relatively thermophilic bacteria and used as an inoculation source. Therefore, if the temperature is too low or too high, the growth rate and metabolic activity of thermophilic bacteria will be inferior.

The step of fermenting the mixed solution with the anaerobic cancer can be carried out at a cultivation temperature of 40 to 60 ° C which is a humid environment, but it is carried out while maintaining the temperature of 48 to 52 ° C, which is the optimum growth rate and metabolic activity of the thermophilic bacteria It is most efficient in increasing hydrogen production.

At the stage of fermenting the anaerobic digester sludge and the mixture of high-protein waste, the intensity of the shaking affects the hydrogen production. This is because the physical mixing state of the anaerobic digester sludge and the high-protein waste changes depending on the intensity of the shaking. Shaking can be done through a shaking incubator or through other physical agitation methods.

In the step of fermenting anaerobic cancer in the prepared mixed solution, fermentation through shaking culture is most effective in increasing the hydrogen production amount. Shaking was carried out through a shaking incubator, and the rotation speed of the shaking incubator was set at 150 revolutions per minute. However, the method of shaking and the rotation speed of the shaking incubator are not necessarily limited to this, but may vary depending on such factors as the anaerobic digester sludge and the concentration of high-protein waste.

Bacteria belonging to the Clostridium genus such as Clostridium aceticum produce acetic acid using hydrogen and carbon dioxide through the reaction shown in the following reaction formula (1).

[Reaction Scheme 1]

4H ₂ + 2CO ₂ -> CH ₃ COOH + 2H ₂ O

Therefore, in order to prevent the process of acetic acid production consuming hydrogen, making the inside of the reactor an environment free of carbon dioxide may help hydrogen production. However, this is not always the case, and it is also possible to obtain greater hydrogen production when fermenting in an environment in which carbon dioxide is present by other factors.

The step of fermenting the mixed solution with the anaerobic can be performed by forming an environment in which carbon dioxide is not present in the head space of the reactor. At this time, the environment in which carbon dioxide is not present in the head space of the reactor can be formed by connecting a container containing an aqueous solution of 70 to 80% (W / W) sodium hydroxide to the head space of the reactor. At this time, the lower the concentration of aqueous sodium hydroxide solution, the lower the removal efficiency of carbon dioxide. Therefore, the use of a high concentration of sodium hydroxide solution can maximize the effect of absorbing carbon dioxide with a minimum volume.

Anaerobic digester sludge includes Clostridium bifermentans , Clostridium butyricum), Clostridium tee beauty rikum (Clostridium tyrobutyricum), Clostridium Bay jerin keuki (Clostridium beijerinckii), Clostridium acetonitrile Beauty rikum (Clostridium acetobutylicum ), Enterobacter aerogenes ), Enterobacter cloacae , Citrobacter < RTI ID = 0.0 > intermedius , Citrobacter freundii , Klebsiella pneumoniae , < RTI ID = 0.0 > Themotoga neapolitana , Bacillus coagulans), Bacillus Mega teryum (Bacillus megaterium , etc.) may be involved in some or all of the bacteria involved in hydrogen production using anaerobic cancer fermentation. Some or all of the bacteria contained in anaerobic digester sludge produce hydrogen through anaerobic digestion of the waste.

In the anaerobic digester sludge, Clostridium non peolmen Tansu (Clostridium bifermentans), Clostridium beauty rikum (Clostridium butyricum), Clostridium tee beauty rikum (Clostridium tyrobutyricum), Clostridium Bay jerin keuki (Clostridium beijerinckii), Clostridium acetonitrile Beauty rikum (Clostridium acetobutylicum ), Enterobacter aerogenes ), Enterobacter cloacae , Citrobacter < RTI ID = 0.0 > intermedius , Citrobacter freundii , Klebsiella pneumoniae), Te Nea motto is poly Tana (Themotoga neapolitana), Bacillus core oysters Lance (Bacillus coagulans , and Bacillus megaterium , and the step of fermenting the anaerobic canal is performed by the bacteria contained in the anaerobic digestion tank sludge. However, the present invention is not limited to the above-mentioned bacteria, and any bacterium can be used as long as it is a bacterium capable of producing hydrogen through fermentation of anaerobic fungi of waste.

According to the present invention, a method for obtaining a high hydrogen production rate using high-protein waste is provided. The present invention is also useful in terms of both environmental protection and efficiency of hydrogen production since it can produce hydrogen with high efficiency compared with the conventional method through the process of fermentation of anaerobic cancer of high-protein waste, Do.

Hydrogen produced in accordance with the present invention can be used as a raw material for the production of gasoline, methanol, ethanol, ammonia, hydrochloric acid and other high value-added compounds, protective gas in welding methods such as atomic hydrogen welding, A hydrogenating agent, a rotor cooling liquid in electric power generation, and the like.

FIG. 1 is a graph showing cumulative hydrogen production (A), cumulative methane production (C), and cumulative carbon dioxide production (C) in Comparative Examples 1 to 4.
2 is a graph showing cumulative biogas production (A), cumulative hydrogen production (C) cumulative carbon dioxide production, and cumulative methane production (A) in Examples 1 to 4;
3 is a graph showing cumulative hydrogen production (A) and cumulative methane production (B) in Examples 5 to 7;
4 is a graph showing cumulative biological gas production (A), cumulative hydrogen production (C), cumulative carbon dioxide production (D) cumulative methane production in Examples 8 to 11;
5 is a graph showing cumulative biological gas production (A), cumulative hydrogen production (C), cumulative carbon dioxide production (D) cumulative methane production in Examples 12 to 15.

Manufacture of high-protein waste models

Since high-protein waste refers to wastes containing protein as a main constituent, not only food wastes but high-protein wastes can be treated as waste such as sewage waste, agricultural waste, animal wastes, and industrial wastes. However, high-protein waste is expected to be a high-protein food waste including high-protein meat. Therefore, in the following examples, high-protein food waste was used.

An artificial high protein food waste model was prepared for the experiment using high protein food wastes with uniform composition. Korean traditional food waste composition is known as rice, cooked meat and vegetables. The cattle lean meat was cooked in boiling water for 8 minutes to prepare a high protein food waste model to be used in the following examples. The prepared high protein food waste model was stored in a freezer at -20 ℃ until the experiment. The amount of total solids and volatile solids (VS) was measured by a conventional method (APHA, 1998).

Anaerobic digester sludge  Preparation and heat treatment

Anaerobic digester sludge for the experiment was collected at Yongin sewage treatment plant. The collected anaerobic sludge sludge was sieved and stored in a refrigerator at 4 ° C until the experiment.

In the case of the embodiment using the heat-treated anaerobic digester sludge, the anaerobic digester sludge was incubated at 50 ° C for 24-72 hours and then heat-treated at 105 ° C for 2 hours. However, the heat treatment method of the anaerobic digester sludge is not limited to this, and any method of heat treatment that can remove the methanogenic bacteria that do not form spores can be used.

Anaerobic digester sludge and  Of a high-protein waste mixture Anaerobic fermentation  Culture method

A 1 L glass flask was used as the fermentation reactor. The total volume of the anaerobic digester sludge and the high-protein waste mixture per reactor was adjusted by adding tap water to a final volume of 0.35L. The loading rate of volatile solids per reactor was 3.0 g VS / L. However, the total volume of the anaerobic digester sludge and the high-protein waste mixture and the loading rate of the volatile solids can be set differently, but are not limited thereto.

The fermentation reaction was carried out in a dark room incubator in which the temperature was uniformly maintained at 50 ± 2 ° C. However, the incubation temperature is not necessarily limited to this temperature, but it is sufficient that the thermophilic bacteria can be activated.

When shaking culture was carried out, the rotation speed of the shaking incubator was set to 150 cycles per minute. However, the method of shaking is not necessarily limited to the method through a shaking incubator, and a method of using a stirrer installed in the reactor can also be used. Also, the rotation speed of the shaking incubator is not necessarily limited to this, and may be set differently depending on factors such as the concentration of the anaerobic digester sludge and the high-protein waste.

During the fermentation reaction, all the reactors were sealed with a rubber cap and a screw cap, and the head space of the reactor was filled with nitrogen gas for about 10 minutes before the reaction so that it became anaerobic.

 During the fermentation of the mixed liquor, the pH was controlled using 1N NaOH and 1N HCl and maintained at a constant level during the fermentation reaction. The environment in which carbon dioxide was not present in the headspace of the reactor was also established by connecting a sealed vessel containing an 80% (w / w) aqueous solution of sodium hydroxide to the headspace of the reactor. However, the method of forming the headspace of the reactor into the environment free of carbon dioxide is not necessarily limited to the above method, and any method can be used as long as it can remove carbon dioxide from the headspace.

In order to investigate the relationship between fermentation conditions of anaerobic cancer and hydrogen production rate, The difference was in the condition of the anaerobic digester sludge treated with and without heat treatment. F / M ratios were 4, 6, and 9, respectively. The pH of fermentation broth was 7.2, 8.2 and 9.2, respectively. In addition, shaking culture conditions in the environment in which the carbon dioxide present in the headspace _{(No CO 2 Trap &Shaking;} NTS), shaking culture conditions in an environment where there is no carbon dioxide in the head space _{(CO 2 Trap &Shaking; TS} ), the head No CO ₂ Trap & No Shaking (NTNS), conditions cultured without shaking (CO ₂ Trap & No Shaking; TNS) in an environment free of carbon dioxide in the headspace, Respectively.

Biogas generated through fermentation reaction biogas ) Analysis method

The pressure of the reactor headspace was measured using a pressure gauge. To use as an initial condition for the next measurement, biogas in the headspace was released (headspace pressure release) and the pressure in the headspace was again measured. The volume of the biogas was also calculated by using the difference between the pressures before and after the generation of the biogas, using the ideal gas law corrected to standard conditions as shown in Equation 1 below.

[Equation 1]

_{^{V Biogas 1) = (P 2}} ) · V Head 3) · C 4)) / (R 5) · T 6))

1) V _Biogas = volume of biogas produced per day (L),

2) P = absolute pressure difference (Pa),

3) V _Head = volume of head space (L),

4) C = mole volume (22.41 L · mol ^-1 ),

5) R = universal gas constant (83.14 L · mbar · K ^-1 · mol ^-1 ),

6) T = absolute temperature (K).

Biogas was collected after exporting the biogas in the headspace using a gas-tight glass syringe. The biogas was analyzed for hydrogen, methane and carbon dioxide by gas chromatography with a stainless steel column and a thermal conductivity detector (TCD) filled with 100/120 mesh HayeSep DB . A standard gas composed of methane (30 ± 2%, v / v), hydrogen (30 ± 2%, v / v) and carbon dioxide (40 ± 2%, v / v) is used to measure the biogas component content Value calibration and calculation. Ar gas was used as a carrier gas and the carrier gas flow rate was 30 ml / min. The oven, injector and detector temperatures were maintained at 100 ° C, 120 ° C and 120 ° C, respectively, during the gas chromatographic measurement, and the volume of the sample was 100 μl.

Mechanical modelling ( kinetic modeling ) Way

The cumulative hydrogen yield curve was applied to a modified Gomertz equation expressed as Equation 2 below.

[Equation 2]

In the above equation 2 'H' is the time accumulated hydrogen production (ml) per (h), 'P' represents a hydrogen production potential (ml), 'R _m' is the maximum hydrogen production rate (ml / h), 'λ ' is the inductive 'L' represents the lag phase time, 't' represents the incubation time (h), and 'e' represents the natural constant. 'P', ' _Rm ', and 'λ' were estimated as Newtonian algorithm through Excel for each batch. The theoretical yield of hydrogen production was calculated by dividing the 'P' by the mass of the initial volatile solids in the reactor.

[ Example  And Test Example ]

Hereinafter, examples and test examples are presented to facilitate understanding of the present invention. However, the following examples and test examples are provided only for a better understanding of the present invention, and the present invention is not limited by the examples and the test examples.

Comparative Example 1 ~ 4: Do not heat  Not Anaerobic digester sludge and  Through the cultivation of a mixture of high-protein waste Anaerobic fermentation

The anaerobic digester sludge was mixed with high-protein waste to an F / M ratio of 6 without heat treatment. The thus prepared mixed solution was anaerobically fermented at 50 DEG C according to the conditions shown in Table 1 below. The comparison between this comparative example and the example shows the relationship between the presence or absence of heat treatment and the hydrogen production rate of the anaerobic digester sludge.

F / M ratio The pH of the mixed solution Presence or absence of binge Presence of carbon dioxide in the headspace Comparative Example 1 6 7.2 O X Comparative Example 2 6 8.2 O X Comparative Example 3 6 9.2 O X Comparative Example 4 6 10.2 O X

Example  1 to 4: Shaking  And Headspace  Of Hydrogen Production Rate with or without Carbon Dioxide

The anaerobic digester sludge was heat treated and mixed with high protein waste to an F / M ratio of 6. The thus prepared mixed solution was subjected to anaerobic membrane fermentation at 50 DEG C according to the conditions shown in Table 2 below. The change of the hydrogen production rate depending on the presence or absence of shaking and the presence or absence of carbon dioxide in the head space can be recognized through the present embodiment.

F / M ratio The pH of the mixed solution Presence or absence of binge The presence of carbon dioxide in the headspace Example 1 6 8.2 O X Example 2 6 8.2 O O Example 3 6 8.2 X X Example 4 6 8.2 X O

Example  5 to 7: pH Of hydrogen production rate

The anaerobic digester sludge was heat treated and mixed with high protein waste to an F / M ratio of 6. The mixed solution was anaerobically fermented at 50 캜 according to the conditions shown in Table 3 below. The change in the hydrogen production rate according to the pH of the mixed solution can be determined through this embodiment.

F / M ratio The pH of the mixed solution Presence or absence of binge The presence of carbon dioxide in the headspace Example 5 6 7.2 O X Example 6 6 8.2 O X Example 7 6 9.2 O X

Example  8 to 15: Anaerobic digester sludge and  Change of hydrogen production rate according to F / M ratio of high-protein waste mixture

After anaerobic digester sludge was heat treated, the high protein waste and F / M ratio were mixed so that the ratio was 4 and 9, respectively. The thus-prepared mixed solution was anaerobically fermented at 50 캜 according to the conditions shown in Table 4 below. Through the present embodiment and Examples 1 to 4, the change of the hydrogen production rate according to the F / M ratio of the anaerobic digester sludge and the high-protein waste mixture can be determined.

F / M ratio The pH of the mixed solution Presence or absence of binge The presence of carbon dioxide in the headspace Example 8 4 8.2 O X Example 9 4 8.2 O O Example 10 4 8.2 X X Example 11 4 8.2 X O Example 12 9 8.2 O X Example 13 9 8.2 O O Example 14 9 8.2 X X Example 15 9 8.2 X O

Test Example  1 to 4: Anaerobic digester sludge  Change of Hydrogen Production Rate with and Without Heat Treatment

1 shows (A) cumulative hydrogen production, (B) cumulative methane production, and (C) cumulative carbon dioxide production in Comparative Examples 1 to 4. Also, ◆ indicates the pH 7.2 condition, ◇ indicates the pH 8.2 condition, ■ indicates the pH 9.2 condition, and □ indicates the pH 10.2 condition.

As shown in (A) of the present comparative example, hydrogen production is almost linear until about 50 hours before the methanogenic bacteria are not activated, and hydrogen production is reduced from 50 hours after methane-producing bacteria start to produce methane Can be confirmed. This is presumably because the methanogenic bacteria of the anaerobic digester sludge are hydrogenotrophic methanogens that produce hydrogen using hydrogen.

Also, the pH 7.2 and pH 8.2 conditions of the methanogenic bacterium in this comparative example (B) show that methane is generated even in an environment where no carbon dioxide is present in the headspace. This is presumably because methane production is possible by using carbon dioxide dissolved in the culture solution. From these results, it can be concluded that the efficiency of methane production is very high in case of fermentation using high protein substrate, unlike the case of using other substrate.

On the other hand, methane is not detected in the pH 9.2 and pH 10.2 conditions where the metabolic activity of the methanogenic bacteria is inhibited, and a small amount of hydrogen is produced. These results suggest that the removal of carbon dioxide using a carbon dioxide remover is not enough to inhibit methane production and promote hydrogen production in the case of hydrogen production using high - protein substrates.

Therefore, in order to produce hydrogen efficiently using a high-protein substrate, it can be concluded that a method that inhibits the activity of the methanogenic bacteria and does not interfere with the metabolic activity of the hydrogen-producing bacteria can be concluded. At this time, the method of maintaining the pH of the mixed solution at a high level inhibits the metabolic activity of the hydrogen-producing bacteria as shown in (A) of the present example, which is not an appropriate method. In order to specifically inhibit only the activity of the methanogenic bacteria, it is necessary to remove the methanogenic bacteria by heat treatment using the characteristics of the methanogenic bacteria that can not form spores.

In Examples 1 to 4, the anaerobic digester sludge was heat-treated and then mixed with high-protein waste to anaerobically ferment the same. 2 shows cumulative biogas production (A), cumulative hydrogen production (C), cumulative carbon dioxide production (D), and cumulative methane production (A) in Examples 1 to 4. Also,  indicates the NTS condition, ◯ indicates the TS condition, ▴ indicates the NTNS condition, and △ indicates the TNS condition.

The induction period (λ), maximum hydrogen production rate (R _m ), hydrogen production potential (P), and hydrogen production rate per volatile solids calculated from the data measured in Examples 1 to 4 are shown in Table 5 below.

Experimental conditions
variable ? (h) R _m (ml / h) P (ml) H ₂ production rate
(ml / g VS) r ² TS 28.5 2.8 227 216.2 0.99 NTS 25 3 260 247.6 0.99 TNS 35 1.2 59.5 56.7 0.98 NTNS 30 1.4 63 60 0.99

Through these test examples, it can be confirmed that the heat treatment process of the anaerobic digester sludge is an excellent method that inhibits the activity of the methanogenic bacteria and does not interfere with the metabolic activity of the hydrogen producing bacteria. Among the results of this test example, the hydrogen production rate confirmed under the TS condition NTS is the best hydrogen production method using the protein reported so far as a substrate. Among them, cultivation under NTS condition shows the highest hydrogen production rate. In addition, it can be confirmed that the difference in hydrogen production rate is greater depending on whether or not shaking is performed as compared with the presence of carbon dioxide. Also, as shown in FIG. 2 (C), it was found that no carbon dioxide was present in the headspace under both the TS and NTS conditions. This suggests that the carbon dioxide removal method in the headspace with 80% aqueous sodium hydroxide solution is very effective.

Test Example  5 to 7: pH Of hydrogen production rate

3 shows (A) cumulative hydrogen production and (B) cumulative methane production in Examples 5-7. Also, ◆ indicates pH 7.2, ◇ indicates pH 8.2, and ■ indicates pH 9.2.

The induction period (λ), the maximum hydrogen production rate (R _m ), the hydrogen production potential (P) and the hydrogen production rate per volatile solids calculated from the data measured in Examples 5 to 7 are shown in Table 6 below.

Experimental conditions
variable ? (h) R _m (ml / h) P (ml) H ₂ production rate
(ml / g VS) r ² pH 7.2 135 2.4 56 53.3 0.77 pH 8.2 6.5 3 227 216.2 0.99 pH 9.2 18 1.1 65.3 62.2 0.98

According to these test examples, it can be seen that the difference in the hydrogen production rate is caused by the pH control of the mixed solution, and the test example of the pH 8.2 condition shows the highest hydrogen production rate.

Test Example  8 to 15: Anaerobic digester sludge and  Change of hydrogen production rate according to F / M ratio of high-protein waste mixture

FIG. 4 shows the case where the F / M ratio is 4 and F (cumulative amount of methane production) by measuring the cumulative biological gas production amount, the cumulative hydrogen production amount, the cumulative carbon dioxide production amount and the cumulative methane production amount of Examples 8 to 15, / M ratio of 9 is shown in Fig. In Figs. 4 and 5,  indicates the NTS condition, ◯ indicates the TS condition, ▴ indicates the NTNS condition, and Δ indicates the TNS condition.

In addition, in the case where the F / M ratio is 4, the induction period (λ), the maximum hydrogen production rate (R _m ), the hydrogen production potential (P), and the hydrogen production rate per volatile solids calculated from the data measured in Examples 8 to 15, 7, and an F / M ratio of 9 is shown in Table 8 below.

Experimental conditions
Variable (F / M ratio = 4) ? (h) R _m (ml / h) P (ml) H ₂ production rate
(ml / g VS) r ² TS 8 1.6 86 81.9 0.98 NTS 11 0.9 105 100 0.96 TNS 32 0.8 95 90.5 0.99 NTNS 30 0.8 71 67.6 0.99

Experimental conditions
Variable (F / M ratio = 9) ? (h) R _m (ml / h) P (ml) H ₂ production rate
(ml / g VS) r ² TS 18 2.3 135 128.6 0.98 NTS 28 3.1 100 95.2 0.89 TNS 32 1.4 61 58.1 0.99 NTNS 32 1.8 55 52.4 0.90

According to these test examples and the above Table 5 of Test Examples 1 to 4, it can be seen that a difference in hydrogen production rate occurs due to the adjustment of the F / M ratio, and the condition where the F / M ratio is 6 is the highest hydrogen production rate As shown in Fig.

Claims (14)

Heat treating the anaerobic digester sludge;
Preparing a mixture of the heat-treated anaerobic digester sludge and high-protein waste; And
And fermenting the anaerobic cancer by culturing the prepared mixed solution in a dark place
(METHOD OF PRODUCING HYDROGENIC WASTE WATER BY USING ANTERIOR LIQUID FERMENTATION).
The method according to claim 1,
Wherein the heat treatment of the anaerobic digester sludge is performed by incubating the anaerobic digester sludge at 40 to 60 ° C for 24 to 72 hours and then heating at 100 to 110 ° C for 1 to 2 hours
(Method of Hydrogen Production by Fermentation of Anaerobic Cancer of High - Protein Waste.
The method according to claim 1,
Wherein the high-protein waste is selected from high-protein food waste, high-protein sewage waste, high-protein agricultural wastes, high-protein animal wastes, high-protein industrial wastes
(Method of Hydrogen Production by Fermentation of Anaerobic Cancer of High - Protein Waste.
The method according to claim 1,
Wherein the mixing ratio of the heat-treated anaerobic digester sludge to the high-protein waste mixture is such that the F / M ratio is 4 to 9
(Method of Hydrogen Production by Fermentation of Anaerobic Cancer of High - Protein Waste.
5. The method of claim 4,
The mixing ratio of the heat-treated anaerobic digester sludge to the high-protein waste mixture is such that the F / M ratio is 6
(Method of Hydrogen Production by Fermentation of Anaerobic Cancer of High - Protein Waste.
The method according to claim 1,
Wherein the step of fermenting the mixed solution with anaerobic cancer is performed while maintaining the pH of the mixed solution at 7.0 to 9.0
(Method of Hydrogen Production by Fermentation of Anaerobic Cancer of High - Protein Waste.
The method according to claim 6,
And the pH of the mixed solution is maintained at 8.2.
(Method of Hydrogen Production by Fermentation of Anaerobic Cancer of High - Protein Waste.
The method according to claim 1,
Wherein the step of fermenting the mixed solution with anaerobic culture is carried out while maintaining the culture temperature at 40 to 60 ° C
(Method of Hydrogen Production by Fermentation of Anaerobic Cancer of High - Protein Waste.
9. The method of claim 8,
Wherein the culturing temperature is maintained at 48 to 52 캜.
(Method of Hydrogen Production by Fermentation of Anaerobic Cancer of High - Protein Waste.
The method according to claim 1,
Characterized in that the step of fermenting the mixed solution with anaerobic cancer is carried out by shaking culture
(Method of Hydrogen Production by Fermentation of Anaerobic Cancer of High - Protein Waste.
11. The method of claim 10,
Characterized in that the shaking is carried out using a shaking incubator at 100 to 200 revolutions per minute
(Method of Hydrogen Production by Fermentation of Anaerobic Cancer of High - Protein Waste.
The method according to claim 1,
Wherein the step of fermenting the mixed solution with anaerobic cancer is performed by forming an environment in which no carbon dioxide is present in the head space of the reactor
(Method of Hydrogen Production by Fermentation of Anaerobic Cancer of High - Protein Waste.
13. The method of claim 12,
The environment in which no carbon dioxide is present in the head space of the reactor is characterized by connecting a container containing an aqueous solution of 70 to 80% (W / W) sodium hydroxide to the head space of the reactor
(Method of Hydrogen Production by Fermentation of Anaerobic Cancer of High - Protein Waste.
The method according to claim 1,
In the anaerobic digester sludge,
Clostridium bifermentans , Clostridium butyricum), Clostridium tee Beauty rikum (Clostridium tyrobutyricum), Clostridium Bay jerin keuki (Clostridium beijerinckii ), clostridium acetobutyricum acetobutylicum ), Enterobacter aerogenes ), Enterobacter cloacae , Citrobacter < RTI ID = 0.0 > intermedius , Citrobacter freundii , Klebsiella < RTI ID = 0.0 > pneumoniae , < RTI ID = 0.0 > Themotoga neapolitana , Bacillus coagulans) and Bacillus Mega teryum (Bacillus megaterium , and the like.
Wherein the step of fermenting the anaerobic canal is performed by the bacteria contained in the anaerobic digestion tank sludge.

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