JP3165499B2 - Microalgae culturing apparatus and culturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for mass-culture of microalgae utilizing a photosynthetic reaction.

[0002]

2. Description of the Related Art Microalgae (phytoplankton having a size of several microns to several tens of microns) are multiplied by a photosynthetic reaction, and a product is used as a resource. For example, Spirulina (blue-green algae) is used as a protein source, Chlorella (green algae) is used as a health food, and Donariella (green algae) is used as a pigment or vitamin A. An industrial-scale culture system for large-scale culture has been completed. .

FIG. 4 shows an example of the prior art relating to a mass-cultivation apparatus for microalgae which is industrialized, and a typical spirulina culture will be described. In FIG. 4, 1
Is a culture tank for microalgae and has a structure in which the sunlight receiving area is wide at a shallow water depth of usually about 30 cm. The culture medium 2 is a mixture of the seeds of the microalgae 30 and the nutrient medium 4 introduced therein. The culture medium is stirred and mixed with a paddle 3. The nutrient medium 4 stored in the medium tank 5 opens the valve 6, and the pump 6 At 7, it is made to flow into the culture tank 1. The produced algal body is opened by opening the valve 8 and withdrawn by the pump 9, and a new liquid, that is, the nutrient medium 4 is replenished by the withdrawn amount.

[0004] Restrictions of the prior art: Since the conventional method is performed under the condition of stable sunlight (continuous sunny weather) and low rainfall, the growth of microalgae (algae) is relatively high. It is stable and thus it is possible to continuously withdraw the growing alga bodies little by little, while injecting them continuously little by little, but only in favorable climatic conditions.

[0005] (1) Problems of the prior art: In Japan, where the amount of rainfall is large, the amount of sunshine, the length of sunshine and the like fluctuates, in Japan, the state is constant at regular intervals (for example, once a day, once every two days, etc.). It is practically impossible to perform the operation of extracting the product or to perform the operation of continuously extracting the product, and the microorganisms in the culture tank may be weakened or the function may be reduced.

[0006]

The growth rate (production rate) of microalgae varies depending on the amount of sunlight (light intensity), water depth, and the concentration of microalgae (algae) in the culture tank. 〇 Insolation (Ly / D = Langre / day = 10 kcal /
(expressed in m ² days) has a significant effect, and the growth rate increases as the amount of sunlight increases. The deeper the water, the lower the concentration of microalgae. In other words, if the water depth is large, the transmission of light from the surface becomes poor, so that the concentration does not become high.方法 There has been no study on a method for stably growing microalgae in response to changes in environmental conditions and for collecting (pulling out) the produced alga bodies in a timely manner.

The present invention has been made in view of the above-mentioned technical level, and aims to provide an apparatus and a method capable of stably growing microalgae and recovering the produced algal bodies with good timing.

[0008]

Means for Solving the Problems The present invention provides the following (1)-
A solution to the above problem by adopting the configuration of (3)
It is. (1) A microalgae concentration meter for measuring the microalgae concentration in a culture solution by supplying carbon dioxide into a culture solution in which the microalgae inhabit and irradiating the carbon dioxide with light to culture the microalgae. A dosimeter for measuring the light irradiation amount, a liquid depth meter for measuring the liquid depth of the culture solution, and a measurement of the irradiation amount meter and the liquid depth meter.
Extraction of constant value, pre-input sunshine amount, liquid depth and culture solution
Calculate the limit concentration from the relationship information with the limit concentration to be collected,
Whether the measured value of the microalgae densitometer has reached the limit concentration
A microalgae culturing apparatus, comprising: a computing unit for determining whether the microalgae is in the microalgae.

(2) In a method of culturing microalgae by supplying carbon dioxide into a culture solution in which microalgae inhabit and irradiating the microalgae with light, a radiation meter for measuring the amount of light irradiation is used. A predetermined limit concentration signal of microalgae obtained by arithmetic processing of a light irradiation amount signal and a liquid depth signal from a liquid depth meter that measures the liquid depth of the culture solution, and a microalgae in the culture solution. The microalgae concentration signal from the microalgae densitometer for measuring the concentration is arithmetically processed, and the microalgae concentration is measured for the microalgae.
A part of the culture solution is collected when the concentration of the light reaches the maximum limit in the irradiation amount of the light and the culture solution depth , and the culture solution or the microalgae having a low microalga concentration depending on the amount of the culture solution recovered. A method for culturing microalgae, which comprises supplementing a nutrient medium in which no microorganisms live.

(3) The method for culturing microalgae according to the above (2), wherein each measurement and calculation processing, collection of the culture solution, and replenishment of the culture solution or the nutrient medium are performed by an automatic control system. .

[0011]

(1) The pattern of the concentration increase when the algal body grows shows a complicated behavior unless the amount of sunshine is always constant, and is difficult to predict. Therefore, if information data on the limit concentration with respect to the amount of sunlight is acquired in advance and introduced into the system equipment, it can be pulled out and collected at the time when the weather is actually bad and the amount of sunlight decreases and the algal cells are becoming weak. The limit concentration here means that when the algal cells exceed a predetermined concentration, light does not enter sufficiently, and the algal cells undergo a reaction opposite to photosynthesis, that is, a respiratory reaction, and as a result, the algal cells become weak and active Means the concentration at which the phenomenon of decrease occurs.

(2) Since the relationship between the liquid depth and the limit concentration to be withdrawn is input even when the liquid depth is increased due to rainfall or the liquid depth is decreased due to evaporation, it is necessary to determine whether the growth is continued or withdrawn. It can be determined automatically.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG. In FIG. 1, 1 is a micro algae culture tank, 2 is a culture solution, 3 is a paddle, 4 is a nutrient medium, 5 is a medium tank, 7,
9 and 22 are pumps, 10 is a sunshine meter, 11 and 16 are a liquid depth meter, 12 is an algal body densitometer, 13 is a calculator, 14 and 17 are solenoid valves, 15 and 18 are timers, 19 is a controller,
21 is a gas tank, 23 is an air diffuser, and 30 is microalgae.

A CO ₂ gas or a combustion exhaust gas is stored in a gas tank 21 as a carbon source for microalgae photosynthesis, and is introduced into the culture tank 1 by a pump 22. This is a means for forcibly blowing CO ₂ to increase the growth rate so as to prevent the supply of CO ₂ from being insufficient due to the photosynthetic reaction.

A solar radiation meter 10 is installed on the upper surface of the culture tank 1, and a liquid depth meter 11 and an algal cell densitometer 12 are also arranged.
After the start of the culture, algal cells proliferate with the passage of days.
As shown in, the ultimate concentration of algal cells differs according to the change in the culture tank liquid depth (H) and the amount of sunlight, so the amount of sunlight (average amount of sunlight on that day), the liquid depth, and the concentration of algal cells are detected. This data is processed by the arithmetic unit 13, and a system is configured to operate so as to pull out algal bodies when the actually measured algal body concentration reaches or exceeds the limit concentration.

Accordingly, a means for extracting the time when the limit concentration is reached is adopted, and the amount and time of the extraction are controlled in accordance with the means. As shown in FIG. The solenoid valve 14 opens and the timer 1
The pump 9 is configured to operate only for the time set at 5.

After extracting a predetermined amount of algal cells reaching the limit concentration, the level is detected by the liquid depth gauge 16 and the nutrient medium 4 stored in the medium tank 5 is replenished to the culture tank 1 by the pump 7. In this case, a function of sending a signal to the electromagnetic valve 17 by the controller 19 to open the valve 17 and simultaneously operating the pump 7 linked to the timer 18 may be added.

FIG. 3 shows a specific example of a test based on the basic concept of the present invention, and shows the results of cultivation using a marine genuine eucalypt algae in a culture tank having a liquid depth of 20 cm.
Approximately 8 days after the initial operation, the algal body concentration was
mg / liter, the culture broth was withdrawn about half of the total volume and then re-started with fresh nutrient medium, but the algal cell concentration at this time was diluted with the new nutrient medium (seawater base). Therefore, it became about 140 mg / liter. As described above, a stable cultivation was made possible by the semi-continuous operation method of repeatedly extracting and supplying a new nutrient medium when the concentration reached the limit concentration.

Further, the amount to be withdrawn is 1/4 of the total amount of the culture solution.
By extracting in the range of 3/4 amount, stable culture was possible.

[0020]

According to the present invention, (1) the algal cell limit concentration of the culture solution is detected, and the produced algal cells are extracted. Therefore, the algal cells before the extraction are not damaged, and the next operation cycle can be started up smoothly. (2) Detecting the amount of sunshine, liquid depth, and algal concentration, appropriately setting the timing for extracting the produced algal cells, and setting the amount of extraction within a range of 1/4 to 3/4 of the total amount of the culture solution. As a result, stable semi-continuous operation becomes possible. (3) The microalgae can be cultured automatically by these series of system configurations.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention.

FIG. 2 is a table showing the relation between the ultimate concentration of algal cells corresponding to the amount of sunshine and the liquid depth of the culture tank of the present invention.

FIG. 3 is a table showing specific test data of the present invention.

FIG. 4 is an explanatory view of one embodiment of a conventional microalgal culture system.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshinori Fukuda 2-5-1 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Heavy Industries, Ltd. Head Office (72) Inventor Norio Shioji 2-1-1 Shinama, Araimachi, Takasago-shi, Hyogo Prefecture No. Mitsubishi Heavy Industries, Ltd. Takasago Research Laboratory (72) Inventor Masaaki Negoro 2-1-1, Shinaihama, Arai-machi, Takasago City, Hyogo Prefecture Mitsubishi Heavy Industries, Ltd. Takasago Research Laboratory (56) References JP 50-101576 (JP, A) 61-160656 (JP, U) WO 91/5849 (WO, A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C12M 1/00 C12M 1/36 C12N 1/12 JICST File (JOIS)

Claims (3)

(57) [Claims] 1. A microalga culturing device for culturing microalgae by supplying carbon dioxide to a culture solution in which microalgae inhabit and irradiating the microalgae with light to measure the microalgae concentration in the culture solution. Meter, a radiation meter for measuring the light irradiation amount, a liquid depth meter for measuring the liquid depth of the culture solution , the radiation meter and the liquid
The measured value of the depth gauge, the sunshine amount,
Extract the limit concentration from the information on the relationship with the limit concentration to be withdrawn and collected.
Calculate and the measured value of the microalgae densitometer reaches the limit concentration
A microalgae culturing device, comprising: an arithmetic unit for determining whether or not the microalgae is present. 2. A method for culturing microalgae by supplying carbon dioxide into a culture solution in which microalgae inhabit and irradiating the microalgae with light, the light from a dosimeter for measuring the amount of light irradiation. A predetermined limit concentration signal of microalgae obtained by the arithmetic processing of the irradiation amount signal and the liquid depth signal from the liquid depth meter for measuring the liquid depth of the culture solution, and the microalga concentration in the culture solution The microalgae concentration signal from the microalgae concentration meter that measures the microalgae is calculated, and the microalgae concentration is measured when the microalgae is measured.
A portion of the culture solution is collected when the concentration of the culture solution reaches the limit in the light irradiation amount and the culture solution depth , and a culture solution or microalgae with a low microalga concentration inhabits according to the collected amount of the culture solution. A method for culturing microalgae, which comprises supplementing a nutrient medium which is not used. 3. The method for culturing microalgae according to claim 2, wherein each of the measurement and calculation processing, the collection of the culture solution, and the replenishment of the culture solution or the nutrient medium are performed by an automatic control system.