JPH1042881A - Useful gas producing process using microorganism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject producing process capable of eliminating a gas separator and extremely reducing energy by using carbon dioxide as a purge gas for a fermenter for a green alga fermenting process of a useful gas producing system using a microorganism. SOLUTION: In this system for producing a useful gas such hydrogen using a microorganism, Chlamydomonas sp. strain MGA161 as a marine green alga is cultured by a culture tank 14 in a green alga culturing process 11, a green alga solution 15 is supplied to a fermenter 16 of a green alga fermenting process 12, purging is carried out by using carbon dioxide 19 as a purging gas for the fermenter 16. Consequently, the amount of hydrogen generated in a green alga fermenting process 12 is reduced, an assimilating source in a fermenting solution 17 is increased, the fermenting solution 17 is transported to a hydrogen synthesizing tank 18 of a photosynthesis bacterium process 13 and is fermented and cultured together with Rhodovulum sulfidophilum strain W-12 which is a marine photosynthetic bacterium to produce hydrogen 21 by the useful gas producing process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a useful gas production process using microorganisms, and provides a process technology applied to a reactor for environmental equipment products.

[0002]

2. Description of the Related Art FIG. 2 schematically shows a hydrogen production system using microorganisms such as microalgae according to the prior art. As shown in the figure, the hydrogen production system comprises a green algae culture process 01,
It comprises a green algae fermentation process 02 and a photosynthetic bacteria process 03, each of which is operated in a batch processing operation. Here, in the green algae culture process 01, a culture tank 04 for culturing green algae is provided,
In the green algae fermentation process 02, a fermentation tank 06 for fermenting the green algae liquid 05 from the culture tank 04 is provided.
In photosynthetic bacteria process 03, the fermenter 0
A hydrogen synthesizing tank 08 for synthesizing hydrogen using the fermentation solution 07 from No. 6 is provided.

That is, green algae are cultured in a culture tank 04 in the green algae culture process 01, and a green algae solution 05 obtained here is internally fermented in a fermentation tank 06 of the green algae fermentation process 02, and hydrogen is produced as a fermentation product. A fermentation gas 09 containing (H ₂ ) and a fermentation liquid 07 containing acetic acid, ethanol, etc. are produced.

[0004] Next, in the photosynthetic bacteria process 03,
Hydrogen (H ₂ ) is synthesized in a hydrogen synthesis tank 08 using acetic acid, ethanol, and the like in the fermentation solution 07 as a source of utilization. In addition,
The internal fermentation of green algae in the green algae fermentation process 02 is performed in a dark anaerobic state, but nitrogen (N ₂ ) 010 is charged as a purge gas in order to make the inside of the fermenter 06 anaerobic and promote hydrogen production. Have been.

[0005] That is, nitrogen (N ₂ ) 010
The green algae liquid of No. 6 is purged as fine bubbles to dissolve the dissolved oxygen (O ₂ ) in the liquid.

When the fermentation tank 06 is made anaerobic, hydrogen (H ₂ ) is generated. This hydrogen is quickly discharged to the outside of the system to promote the internal fermentation of green algae, thereby producing hydrogen and producing acetic acid, ethanol and the like. A nitrogen purge is also needed to facilitate production. The fermentation gas 09 was N ₂ , CO ₂ ,
Although it is composed of a mixed gas such as H ₂ , hydrogen (H ₂ ) is separated and purified in a gas separator 011 provided on the gas discharge side of the fermenter 06.

In the above-mentioned prior art, about 1/3 of the total hydrogen is recovered in the green algae fermentation process 02, and about 2/3 of the total hydrogen is recovered in the photosynthetic bacteria process 03.

[0008]

However, in the above-mentioned conventional hydrogen production system, the concentration of hydrogen in the fermentation gas 09 produced in the green algae fermentation process 02 is about 1%.
Therefore, the gas separator 011 needs to be concentrated and purified, but there is a problem that a large amount of energy is required because the hydrogen concentration is low.

On the other hand, hydrogen produced in the photosynthetic bacteria process 03 has a concentration of 90% or more, and the energy required for its concentration and purification is very small. In order to increase the hydrogen concentration in the fermentation gas, even if the amount of nitrogen purge gas is reduced, the hydrogen concentration in the fermentation gas 09 increases at most by only about 1%. There is a problem that the concentrations of acetic acid and ethanol, which are the chemical sources, decrease.

[0010]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have conducted intensive studies. As a result, in the green algae fermentation process, assimilation for generating hydrogen in the following photosynthetic bacteria process is performed. Focusing on producing as much organic matter as possible, not collecting low-concentration hydrogen generated here, but instead recovering as much high-concentration hydrogen as possible at once to improve the efficiency of the system I found that.

Furthermore, as a result of this study, various gases were examined in place of the conventional nitrogen for purging. As a result, it was found that carbon dioxide (CO ₂ ) was suitable for this purpose as a purge gas, and the present invention was completed.

The useful gas production process using microorganisms of the present invention based on such knowledge is characterized in that in a useful gas production system using microorganisms, carbon dioxide is used as a purge gas for a fermenter in a green algal fermentation process. is there.

The microorganism used in the useful gas production process is Chlamydomona, a marine green algae.
s sp. strain MGA161 and the marine photosynthetic bacterium Rhodovulum sulph
idophilum strain W-1S (microorganism accession number: FERM P-15320).

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows a hydrogen production system using micro green algae or the like according to the present embodiment. As shown in the figure, the hydrogen production system is composed of a green algal culture process 11, a green algal fermentation process 12, and a photosynthetic bacteria process 13, and each of the processes is operated by a batch processing operation. Here, in the green algal culture process 11, a culture tank 14 for culturing green algae is provided, and in the green algal fermentation process 12, a fermentation tank 16 for fermenting the green algal solution 15 from the culture tank 14 is provided. . In the photosynthetic bacteria process 13, the fermenter 16
A hydrogen synthesizing tank 18 for synthesizing hydrogen using the fermentation liquid 17 in the above is provided. Further, carbon dioxide (CO ₂ ) 19 is introduced into the fermenter 16 as a purge gas. In FIG. 1, reference numeral 20 indicates fermentation gas and reference numeral 21 indicates hydrogen gas.

In the system according to the present embodiment, green algae are cultured in the culture tank 14, and the green algal solution 15 cultured here is sequentially supplied to the fermentation tank 16. In the fermenter 16, green algae accumulate starch by photosynthesis. Next, in the fermenter 16, the green algae decomposes the accumulated starch into hydrogen and organic compounds (acetic acid, ethanol, glycerin, etc.) under dark anaerobic conditions. The fermented liquid 17 of the organic compound (acetic acid, ethanol, glycerin, etc.) obtained here is moved to the hydrogen synthesizing tank 18 and used as a source of photosynthetic bacteria. In the hydrogen synthesizing tank 18, the photosynthetic bacterium uses an organic compound (acetic acid, ethanol, glycerin, etc.) as a base material for its nitrogenase to produce hydrogen gas 21.

In the system according to the present embodiment, the purge gas in the fermenter 16 is changed from nitrogen to carbon dioxide (CO ₂ ), and the gas for separating the fermentation gas 20 from the fermenter 16 is compared with the conventional system. The separator is omitted. This eliminates the need for a gas separator for concentrating and purifying hydrogen from a dilute fermentation gas, thereby greatly reducing the required energy and simplifying the system.

Further, as a purge gas for purging the inside of the fermenter 16, conventional nitrogen (N ₂ ) to carbon dioxide (CO ₂ )
The main chemical reaction of green algae fermentation when changed to
Formulas (1) to (3) of the following “Formula 1” are obtained.

[0019]

Embedded image <Acetate generation> C ₆ H ₁₂ O ₆ + 2H ₂ O → 2CH ₃ COOH + 2CO ₂ + 4H ₂ (1) <Ethanol generation> C ₆ H ₁₂ O ₆ → 2C ₂ H ₅ OH + 2CO _2. (2) <Glycerol generation> C ₆ H ₁₂ O ₆ + 2H ₂ → 2CH ₈ O ₃ (3)

That is, in the conventional nitrogen purging, the reactions of the above formulas (1) and (2) have occurred, but in the case of purging using carbon dioxide (CO ₂ ) in the present embodiment, In addition, the reaction of the formula (3) is occurring. Therefore, part of the hydrogen generated in the reaction of the formula (1) is used in the reaction of the formula (3), and as a result, glycerol (CH ₈ O ₃ ) is generated. Used as resources for

That is, by changing the purge gas from nitrogen to carbon dioxide, the amount of hydrogen generated in the green algal fermentation process 12 is reduced, and instead, the photosynthetic bacteria process 13 is replaced.
Can increase the resources used in

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below.

This example was carried out under the following test conditions using 100% carbon dioxide (CO ₂ ) as a purge gas. As a comparative example, the test was performed using a conventional system using nitrogen as a purge gas. The test results are shown in Table 1 below.

<Test conditions> Green alga culture alga body: Marine green alga Chlamydomon
as sp. strain MGA161 (rejected as a marine green algae) Photosynthetic bacteria: Marine photosynthetic bacterium Rhodov
ulum sulphidophilum strain
W-1S (microorganism accession number: FERM P-1532)
0) Green algae fermentation purge gas temperature Example: CO ₂ , 30 ° C. Conventional example: N ₂ , 30 ° C.

[0025]

[Table 1] <Test results>

From the results shown in Table 1, the following was confirmed. In the method of the present invention (recovery of only hydrogen generated in photosynthetic bacteria process 13), the hydrogen production amount is 5.89 μmol.
/ Mg algae had a hydrogen concentration of 90% or more. On the other hand, in the conventional method, the hydrogen production amount is 1.68 μmol / mg alga bodies in the green algae fermentation process 02, and the hydrogen concentration is 0.
82%, 2.24 μmol / m in photosynthesis process 03
g Algae with a hydrogen concentration of 90% or more, and a total of 3.92 μmo
1 / mg algae. Accordingly, the method of the present invention can recover only hydrogen having a high hydrogen concentration (90% or more) with a hydrogen production amount about 1.5 times larger than that of the conventional method.

[0027]

As described above, according to the present invention, the hydrogen production system using microalgae and the like comprises a green algal culture process, a green algal fermentation process, and a photosynthetic bacteria process. By changing to ₂ ), the hydrogen production amount becomes about 1.5 times that of the conventional method, and only the gas having a hydrogen concentration of 90% or more can be recovered. Therefore, according to the present invention, the system can be simplified as compared with the conventional recovery method requiring a large amount of energy, and the gas separator used conventionally is not required, and the required energy can be greatly reduced. .

[Brief description of the drawings]

FIG. 1 is a system diagram of a useful gas production process using a microorganism of the present invention.

FIG. 2 is a system diagram of a conventional useful gas production process using microorganisms.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Green alga culture process 12 Green alga fermentation process 13 Photosynthetic bacteria process 14 Culture tank 15 Green alga liquid 16 Fermenter 17 Fermentation liquid 18 Hydrogen synthesis tank 19 Carbon dioxide 20 Fermentation gas 21 Hydrogen gas

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location C12R 1:01) (C12N 1/12 C12R 1:89) (C12N 1/20 C12R 1:01) (72) Inventor Yoshion Miura 21-12, Koyo-sonme Kamiyama-cho, Nishinomiya-shi, Hyogo (72) Inventor Kiyohito 1-8-8 Hachioji, Ikeda-shi, Osaka 204-401 (72) Inventor Isamu Maeda, Osaka-shi, Osaka (72) Inventor Toru Akano 3-2-2 Nakanoshima, Kita-ku, Osaka City, Osaka Prefecture Within Kansai Electric Power Company (72) Inventor Seimi Fukatsu 3-chome Nakanoshima, Kita-ku, Osaka City, Osaka 2-22 Kansai Electric Power Co., Inc. (72) Inventor Hitoshi Miyasaka 3-2-2 Nakanoshima, Kita-ku, Osaka City, Osaka Prefecture Kansai Electric Power Co., Inc. (72) Inventor Hiroyo Matsumoto 2-1-1 Niihama, Niimachi, Takasago City, Hyogo Prefecture Number 1 Inside the Takasago Research Laboratory, Mitsubishi Heavy Industries, Ltd. No. 1 Inside the Takasago Research Laboratory, Mitsubishi Heavy Industries, Ltd. No. 1 Mitsuhishi Heavy Industries, Ltd.

Claims (2)

[Claims] Claims: 1. A useful gas production process using microorganisms in a useful gas production system using microorganisms, wherein carbon dioxide is used as a purge gas for a fermenter in a green algae fermentation process. 2. The microorganism of the useful gas production process according to claim 1, wherein the microorganism is a marine green alga Chlamydomonas.
sp. The strain MGA161 and the marine photosynthetic bacterium Rhodovulum sulfid
Ofilum strain W-1S (microorganism accession number: FERM P-15320).