JPH08116965A - Chlorella t-1 strain and carbon dioxide fixation using the same - Google Patents

Abstract

PURPOSE: To enable proliferation of algae cell bodies even in high CO2 concentration, rather high temperature, high algae concentration and low pH, for example, in such a case that the exhaustion gas from coal combustion power plant is passed through the bioreactor by fixing carbon dioxide gas with a specific microalga. CONSTITUTION: Carbon dioxide is fixed by the cell bodies of chlorella T-1 strain which has about 4μm diameter, one-layer smooth cell wall and thylakoids laying into pyrenoids and the starch sheath divided into two moieties according to the electro-microscopic photograph of the cell bodies. The chlorella T-1 strain causes no change in cell proliferation, even when its pH is changed from 6 to 3 and the proliferation rate is 6 times or more that of general chlorella even in 40-100% CO2 concentration, 5 times or more that of Scenedesmus at 35 deg.C. Further, it proliferates at a rate more than double that of a green alga Ta-1 even in 2% NaCl concentration and the product is useful as a fertilizer, feed, medicine and the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chlorella T-1 strain which is a kind of chlorella and is highly resistant to acidity and high salt concentration and can grow even at a high temperature of 35 to 45 ° C. The present invention relates to a gas immobilization method.

[0002]

BACKGROUND OF THE INVENTION Chlorella is a genus of unicellular green algae and belongs to the order Chlorococales. Some are native to fresh water or seawater, and some are symbiotic to Paramecium, sponge, and the like. It is spherical or oval with a diameter of 3 to 10 μm and has a hard shell. In addition to using organic matter as an energy source, it can grow both nutritionally and by photosynthesis. It is often used as a material for biochemical research such as photosynthesis and protein synthesis.

[0003] The protein content is half of the dry weight, it contains a lot of amino acids such as lysine and nutrients such as unsaturated fatty acids, and it grows fast and can be cultivated throughout the year. Scenedesmus, which appears later as a comparative example, also belongs to green algae, and the cells are round or slightly boat-shaped, forming a colony with several cells. When it breeds a lot, it produces a green grass smell. Used in photosynthesis research.

[0004] The growth rate of conventional chlorella rapidly decreases when the CO ₂ concentration exceeds 20%. With respect to the temperature, in the Sennedesmus strain, when the temperature rises from about 30 ° C, the growth rate sharply decreases. With respect to the salt concentration, when the salt concentration increases from 1% to 2%, the growth rate of green algae such as Senedesmus becomes about 1/3, and it hardly grows at a seawater concentration of 3%. Regarding the pH, the pH of Senedesmus strain is
At 4 the growth rate is about 1/2 and at pH 3 the growth is almost zero.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to fix CO _{2 in} combustion exhaust gas of a coal-fired power generation system or the like by utilizing microalgae and contribute to the suppression of global warming. In the case of aeration of the bioreactor with a high CO ₂ concentration, a high temperature of 30 to 50 ° C., a high salt concentration, and a low pH, in view of the fact that it can withstand and grow in this environment, carbon dioxide can be fed to feed, fertilizer, The aim is to find microalgae that can be immobilized on medicines.

[0006]

[Means for Solving the Problems] The inventors of the present invention have made extensive studies to solve the above problems. As a result, a high CO ₂ concentration, a temperature of 30 to 45 ° C., in a wastewater treatment device of a wet desulfurization device for combustion exhaust gas of a coal-fired power generation system,
It was found that there is a strain of Chlorella that can survive and grow regardless of the environment of high salt concentration and low pH, and completed the present invention.

That is, the present invention is (1) a kind of chlorella having a small diameter of about 4 μm, the cell wall in the electron micrograph of the cell is single and smooth, and thylakoid is intruded into the pyrenoid, and the starch sheath is Chlorella T divided into two parts
-1 share,

(2) Even at pH 3, there is no change in the growth rate as compared with the case of pH 6, and the CO ₂ concentration is 40 to 100.
%, The growth rate was 6 times or more that of general chlorella, 5 times or more that of Senedesmus at a temperature of 35 ° C., and 2% of the green alga Ta-1 at 2% NaCl concentration.
Chlorella T-according to the preceding paragraph (1), which shows a proliferation rate more than double
One share,

(3) In a raceway type bioreactor, the waste water of the wet desulfurization unit of the coal power generation system is used as a culture solution, and a part of the exhaust gas containing CO ₂ after desulfurization is aerated and irradiated with sunlight. , (1), (2) above
By culturing the Chlorella T-1 strain of, the CO ₂ in the exhaust gas is converted and fixed as the Chlorella T-1 strain, and the grown algae are separated and collected and used as fertilizers, feeds, pharmaceuticals, and CO ₂ The removed clean gas is a method of fixing carbon dioxide gas, which is characterized in that smoke is discharged from the chimney.

FIG. 1 is an electron micrograph of Chlorella T-1 strain of the present invention. FIG. 2 is an electron micrograph of Ta-1, which is a green alga. Comparing these two, it is clear that Ta-1 has a diameter of about 10 μm, while T-1
One strain has a small diameter of about 4 μm. The cell wall of Ta-1 is doubled and has a surface pattern, whereas the cell wall of strain T-1 is single and has a smooth surface. The Ta-1 pyrenoid is separated from the fibrous thylakoid and is surrounded by the starch sheath and is independent, whereas the P-1 pyrenoid of the T-1 strain contains the fibrous thylakoid. The starch pod is divided into two parts.

FIG. 3 is a diagram comparing the growth rates of the T-1 strain of the present invention and Senedesmus when the pH of the medium was changed to 3-6. Senedmus has a growth rate of about 0.7 at pH 4 to 6, but can hardly grow at pH 3. In contrast, the T-1 strain of the present invention has a pH of 3-6.
, The average growth rate was 1.3, and it was 1.2 or more at pH 3. This shows that strain T-1 can grow even in a strongly acidic medium.

FIG. 4 is a diagram showing the transition of the culture time (hr) to the algal cell concentration of the T-1 strain of the present invention at each pH. p
In H4 and H6, the alga body concentration increases uniformly with time. At pH 3, the concentration of algal cells decreases slightly for the first 50 hours, but after 60 hours, the same odor as in the case of pH 4 and pH 6 increases. This indicates that strain T-1 acquired resistance to pH.

FIG. 5 is a graph showing changes in the growth rate of the T-1 strain, Senedesmus and green alga (Ta-1) of the present invention when the CO ₂ concentration (%) was changed from 0 to 100%. is there. When the CO ₂ concentration was 40% or more, the growth rate of all strains decreased, but general chlorella decreased to 30% or less compared to air, whereas the T-1 strain showed 12%.
It has increased to 2%. In the T-1 strain, the growth rate of 94% of air is maintained even with 100% of CO ₂ .

FIG. 6 is a graph showing the effect of temperature on the growth rate of T-1 strain and Senedesmus. At 45 ℃, the growth rate decreased sharply in all cases, while in Senedesmus, the growth rate decreased linearly from 1.1 to 0.3 over 30 ℃ to 40 ℃, while in T-1 In stock,
It retains almost 1.75, but rather the growth rate is higher at 40 ° C.

FIG. 7 compares the growth rates of the T-1 strain, green algae (Ta-1) and Senedesmus by salt concentration.
The growth rate of Ta-1 and Senedesmus decreased sharply when the salt concentration became 1% or more, but in the T-1 strain, 1% NaC
In the case of 1, the growth rate is almost 0% NaCl and becomes 2% NaCl, and the growth rate is halved from 1% NaCl for the first time.
Even so, with 2% NaCl, more than twice the amount of green algae (Ta-1),
It shows a growth rate of about 3 times.

FIG. 8 is a diagram showing the relationship between the culture time (hr) of the T-1 strain and the concentration of algal cells using the salt concentration as a parameter. The T-1 strain showed a uniform distribution up to a salt concentration of 2%. The concentration increases with time, and the concentration decreases once even if the salt concentration is 3%, but after 200 hours, the concentration starts to increase, indicating that the salt concentration is resistant.

As a method of utilizing this Chlorella T-1 strain, it can be considered to utilize it for a carbon dioxide gas fixing system in the combustion gas of a coal-fired power generation system. Since it was found in the wet gas desulfurization equipment wastewater treatment equipment of this coal-fired power generation system, the salt concentration is high in the acidic region,
It is expected that the temperature will grow higher than room temperature,
It was confirmed in the above test. Therefore, the global warming caused by the increase of carbon dioxide level in the atmosphere has become a global problem. By utilizing this, carbon dioxide in exhaust gas is fixed as Chlorella T-1 strain, and Chlorella T-1 strain is used. Since the nutrients required for the growth of chlorella are contained in the wastewater of the desulfurization unit rather than the combustion gas of coal, it is only necessary to irradiate the sunlight necessary for the growth of the Chlorella T-1 strain. Chlorella T- that can utilize gas for fertilizer, feed, pharmaceuticals, etc.
It can be fixed to one strain.

[0018]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples. With reference to FIG. 9, an apparatus for immobilizing carbon dioxide gas from the combustion exhaust gas of the coal-fired power generation system using the Chlorella T-1 strain will be described with a diagram.
A boiler 1 burns coal 14 to generate high-pressure steam that rotates a power generation turbine. The steam system will be omitted, and the combustion gas system will be described. The combustion gas 16 collects and separates coal ash by the electric dust collector 2, then separates or nitrogenates NOX by the denitration device 3, and separates SOX as gypsum by the wet desulfurization device 4. The exhaust gas containing carbon dioxide is sent to the chimney 10 and becomes the smoke exhaust 17.

Conventionally, the wastewater 13 of the wet desulfurization device is sent to the wastewater treatment device as it is, and is discharged after treating COD and the like to the extent that it does not interfere with the discharge. In the pilot plant of the present invention, this drainage 13 is sent to and circulated in a raceway type reactor 6 such as an athletics track. In the raceway type reactor, carbon dioxide was ventilated from the chimney exhaust gas pipe through the carbon dioxide supply pipe 11 to the reactor 6, and the chlorella T-1 strain of the present invention was propagated under the irradiation of sunlight to generate carbon dioxide. It is fixed and the treated exhaust gas is sent to the chimney via the flue 12. The propagated Chlorella T-1 strain is separated as recovered microalgae 8 by a solid-liquid separator 7 such as a centrifuge, and is effectively used as a plant fertilizer, fish feed, vitamins, amino acids and other pharmaceuticals. The wastewater 18 from which the algae has been separated by the solid-liquid separator 7 is treated by the wastewater treatment facility 9 and discharged as wastewater.

FIG. 10 shows the results of using the raceway type reactor (4 m ³ ) of 150 of Chlorella T-1 strain of the present invention.
The result of having performed the proliferation test for 0 hours is shown. It was found that the algal concentration reached 1,000 mg / l in about 1200 hours, and stable growth was achieved by timely recovery.

FIG. 11 shows the result of a proliferation test (336 hr) of the Chlorella T-1 strain in the drainage of desulfurizers at power plants all over the country.

As shown in FIG. 11, it was found that the chlorella T-1 strain can grow in the wastewater of desulfurization equipment of many coal-fired power plants. FIG. 12 shows the results of the 120-hour actual gas aeration test, which shows the same course of algal cell concentration as when a pure CO _{2 of} 15% was aerated.

[0023]

EFFECT OF THE INVENTION According to the present invention, acidity of up to about pH 3 and 2
% Salt concentration, 100% carbon dioxide concentration, 30-45
It was possible to identify a Chlorella T-1 strain that can grow at a temperature of about 0 ° C. Using this chlorella T-1 strain, it was revealed that the chlorella T-1 strain can be stably propagated in the wastewater of the desulfurization unit of a thermal power plant. Therefore, carbon dioxide gas that had been conventionally emitted to the atmosphere was chlorella T-1. It is valuable as an invention that can be fixed to -1 strain to open the way to fertilizer, feed, and pharmaceuticals, and to suppress global warming.

[Brief description of drawings]

FIG. 1 is an electron micrograph of Chlorella T-1 strain.

FIG. 2 is an electron micrograph of a conventional green alga (Ta-1).

FIG. 3 is a pH characteristic diagram of Chlorella T-1 strain and Senedesmus.

FIG. 4 is a characteristic diagram showing the results of a long-term culture test with varying pH of Chlorella T-1 strain.

FIG. 5: Chlorella T-1 strain, Senedesmus, green algae (Ta
FIG. ₂ is a characteristic diagram showing the growth rate of -1) with respect to changes in CO ₂ concentration.

FIG. 6 is a characteristic diagram showing the growth rate of Chlorella T-1 strain and Senedesmus with temperature change.

FIG. 7 is a characteristic diagram of growth rate constants (kg) when the salt concentrations of Chlorella T-1 strain, green algae (Ta-1) and Senedesmus are changed.

FIG. 8 is a characteristic diagram showing changes in algal cell concentration (mg / l) with time when the salt concentration of Chlorella T-1 strain was changed.

FIG. 9 is a block diagram in which a carbon dioxide immobilization system is configured by applying Chlorella T-1 strain to wastewater of a thermal power station wet desulfurization device and exhaust gas.

FIG. 10 is a graph of growth time-algal concentration in a growth test using a raceway type reactor with Chlorella T-1 strain.

FIG. 11 is a graph showing the growth amount of Chlorella T-1 strain in a desulfurization device drainage medium of thermal power plants all over the country.

FIG. 12 is a time chart of algal cell concentration-time when a 120-hour actual gas aeration test is performed on desulfurization equipment drainage.

[Explanation of symbols]

 1 Boiler 2 Electrostatic Precipitator 3 Denitration Device 4 Wet Desulfurization Device 5 Gypsum 6 Raceway Type Reactor 7 Solid-Liquid Separator 8 Collected Microalgae 9 Wastewater Treatment Device 10 Chimney 11 Carbon Dioxide Gas Exhaust Gas 12 Decarbonation Gas Exhaust Gas 13 Wet Desulfurization Device Wastewater (culture liquid) 14 Coal 15 Discharged water 16 Combustion gas 17 Flue gas 18 Separation liquid 19 Coal ash

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[Procedure amendment]

[Submission date] February 28, 1995

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 4

[Correction method] Change

[Correction content]

[Figure 4]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Minoru Owada Minoru Owada 4-2-5 Kudankita, Chiyoda-ku, Tokyo Inside Denden Greenery Center, Electric Power Company (72) Koichiro Maeda 4-chome, Kudankita, Chiyoda-ku, Tokyo No. 2-5 Stock Company Denden Environmental Greenery Center

Claims (3)

[Claims] 1. A kind of chlorella having a diameter of 4 μm.
Chlorella T-1 strain that is small in the front and back, has a single and smooth cell wall in the electron micrograph of cells, has thylakoids in the pyrenoid, and has a starch sheath divided into two parts. 2. The growth rate does not change even at pH 3 as compared with pH 6, and at a CO ₂ concentration of 40 to 100%, the growth rate is 6 times or more that of general chlorella and the temperature is 35 ° C.
Showed 5 times more growth rate than that of Senedesmus and 2% Na
Chlorella T-1 according to claim 1, which shows a growth rate twice or more that of the green alga Ta-1 and Senedesmus even at a Cl concentration.
stock. 3. In a bioreactor capable of irradiating sunlight into a circulating fluid of a raceway type or the like, the waste water of a wet desulfurization device of a coal power generation system is used as a culture fluid, and CO ₂ after desulfurization is used.
CO ₂ in the exhaust gas is converted and fixed as the Chlorella T-1 strain by culturing the Chlorella T-1 strain according to claim 1 or 2 while aerating part of the exhaust gas containing , Algae that have proliferated from a part of the culture solution are separated and collected and used as fertilizers, feeds, pharmaceuticals, CO ₂
A clean carbon dioxide excluding gas is discharged from a chimney, which is a carbon dioxide immobilization method.