JP2015146788A - Algae culture method and algae culture apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To culture algae inexpensively in high yield without mixing impurities.SOLUTION: Algae and a liquid culture medium are enclosed into a synthetic resin container 2 consisting of a blow molded polyester and the like, the inside of the synthetic resin container 2 is set at positive pressure with respect to the outside, the synthetic resin container 2 enclosing them are connected to construct a floating structure, the floating structure floated on the sea are moored, thereby algae are cultured in the synthetic resin container 2 while floating the synthetic resin container 2, the synthetic resin container 2 is collected after cultivation, and an oil and fat content is extracted and purified.

Description

  The present invention relates to an algae culture method for accommodating algae in a resin container and culturing, and an algae culture apparatus used in the method.

  There is growing interest in biofuels as a substitute for fossil fuels such as petroleum, which are feared to be depleted. Biofuel is a fuel that is produced from biological resources such as plants. As typical biofuels, bioethanol obtained by subjecting sugars such as corn and sugarcane to alcohol fermentation and biodiesel obtained by modifying fats and oils such as vegetable oil are known. However, in the production of conventional biofuels, securing raw materials becomes a problem. In particular, bioethanol raw materials are often used as food, and the expansion of the production of bioethanol causes a rise in food and feed prices, which is a major social problem. Therefore, biofuel production methods that do not affect food supply are being sought.

As a new biofuel raw material, microalgae having the property of producing fats and oils by photosynthesis has attracted attention. Biofuel production using microalgae has higher productivity per unit area than higher plants, which can be used as food and feed after the collection of fats and oils, as opposed to virtually competing with food production. It can be used even on land that is not suitable for the cultivation of higher plants, and has the advantage of being easy to increase the contribution to carbon dioxide fixation in the atmosphere.
For example, Patent Document 1 discloses a method for producing biodiesel by culturing algae outdoors in a bioreactor and extracting oil therefrom.

JP 2012-239423 A

By the way, when culturing a large amount of microalgae, reduction of culture cost is an essential issue. For example, in order to efficiently cultivate microalgae such as Potriococcus brownie, growth conditions such as appropriate nutrients and light are required. For this reason, an open bond method (open system) for culturing in an outdoor pool or the like has been proposed, but there are variations in the nutrients supplied, the effects of contamination with other organisms that interfere with the growth of algae, and There are concerns about environmental impact.
The method described in Patent Document 1 uses a sterilized nutrient-containing solution as a culture solution, which causes an increase in cost.
On the other hand, in the case of a closed system that is cultivated in a closed environment such as in a thermostatic bath, there is no problem like an open system because the cultured algae do not come into direct contact with the outside air, but the quality control cost increases and the production volume It is easy to be limited.

  The present invention has been made in view of such circumstances, and an object of the present invention is to cultivate algae with high efficiency and low cost without impurities being mixed therein.

  The algae culture method of the present invention encloses algae and a liquid medium in a synthetic resin container, and floats on the water or in water in a state where a large number of the synthetic resin containers in which these are encapsulated are assembled. The algae is cultured.

  Since many synthetic resin containers are cultured in the state of being floated on water or in water, they can be cultured in an outdoor pool, the sea, a lake, etc. as in the open system. On the other hand, since each synthetic resin container individually encloses algae and the like, it becomes a closed environment in which the algae inside do not come into direct contact with the outside air.

  In this case, by selecting a container made of an appropriate resin material, the inside of the synthetic resin container in which the algae and the liquid medium are sealed is made positive with respect to the outside. It is preferable to effectively prevent intrusion. Moreover, even if it is a case where other microorganisms mix in a culture medium by making the inside of a synthetic resin container into a positive pressure with respect to the exterior, the growth can be suppressed. In order to make the inside of the synthetic resin container positive, it is easy and economical to contain carbon dioxide in the liquid medium, which is a preferable means. In particular, when cultivating microalgae for photosynthesis, carbon dioxide can also be used as a carbon source for photosynthesis and effectively increase the growth rate. In this case, since the concentration of carbon dioxide contained in the liquid medium can be adjusted by a commercially available apparatus or a raw material blended in the medium, a gas composition in the container suitable for culture can be selected.

Therefore, although it is an open system, it can be cultured with a high quality without impurities as in the closed system. Further, since the synthetic resin container is suspended in water or on water, the liquid medium is appropriately stirred in the synthetic resin container, and the growth can be promoted by bringing the algae into contact with a fresh medium, which is efficient.
In the case of algae growing by photosynthesis, such as Potriococcus brownie, the synthetic resin container may be formed of a transparent material such as a transparent material.
Even if impurities are mixed in a specific synthetic resin container, only the contents of the specific synthetic resin container have to be discarded, and the culture in other synthetic resin containers is not affected.

In this case, it is preferable to construct a floating structure by connecting synthetic resin containers and moor the floating structure floating on the ocean.
By floating on the ocean as a floating structure, it can be cultured at a substantially constant temperature, and can be cultured in large quantities by natural culture. Also, sufficient sunlight can be obtained when culturing algae that grow by photosynthesis.

Further, in the present invention, it is preferable to use a blow-molded polyester container as the synthetic resin container.
Blow molding is a method suitable for economical mass production of hollow molded articles, and can produce containers at low cost.

The algae culture apparatus of the present invention includes a large number of synthetic resin containers filled with algae and a liquid medium, and drift prevention means for holding these synthetic resin containers in an aggregated state.
The drift prevention means is not particularly limited as long as the individual synthetic resin containers can be assembled so as not to be detached. Wires, chains, and the like, nets, and a large number of synthetic resin containers An enclosing frame-like floating body or the like can be applied, but a floating structure that is moored in a state of floating on the ocean by connecting synthetic resin containers may be constructed.
Moreover, the synthetic resin container and the drift prevention means can be recycled by enclosing new algae and a carbonic acid medium after one culture.

In this case, the internal volume of the synthetic resin container is preferably 10 liters to 200 liters. Containers in this range are generally used for beverage containers and the like, and their manufacturing technology has been established. By using these containers, containers can be produced at low cost.
In addition, as described above, the synthetic resin container is preferably formed of a light-transmitting material for culturing algae grown by photosynthesis.

  Although the present invention is in the form of an open system, it can be cultured with high quality without impurities as in the closed system, and since the synthetic resin container is suspended, it is appropriately stirred in the synthetic resin container, Algae can be brought into contact with fresh medium to promote growth and is efficient. Moreover, since the culture can be performed by enclosing the algae and the medium in the blow molded synthetic resin container and leaving them to stand, the initial cost and the maintenance cost can be reduced.

It is a schematic diagram which shows the process of the algal culture method of one Embodiment of this invention. It is a mimetic diagram showing the state where the algal culture device of one embodiment was moored on the ocean as a floating structure. It is an enlarged view which shows a part of algae culture apparatus of FIG. It is explanatory drawing which showed typically the form which divides | segments a synthetic resin container into several groups, culture | cultivates, and collect | recovers individually.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
An algae culture apparatus 1 according to an embodiment includes a large number of synthetic resin containers 2 in which algae (seed algae) 11 and a liquid medium 12 are enclosed, and drift prevention means 3 that holds these in an aggregated state. And an artificial floating structure is constructed on the ocean.

  The synthetic resin container 2 includes a container main body 21 in which algae and the like are stored, and a cap 22 for sealing the mouth portion 21a of the container main body 21. The container body 21 is preferably formed by blow molding (also referred to as hollow molding or blow molding) in terms of productivity. One aspect of blow molding is a hollow molded product along the inner surface of the mold by sandwiching a cylindrical parison made by extrusion molding or injection molding between molds (both not shown) and blowing pressurized air inside. This is a typical method suitable for economical mass production of hollow molded articles.

The material of the synthetic resin container 2 is a synthetic resin that can be blow-molded. The weather resistance, mechanical strength to the extent that it can cope with climate change, and moderate pressure resistance when the inside of the synthetic resin container 2 is positive pressure Polyesters including polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polylactic acid (PLA), polyethylene furancarboxylic acid (PEF), and polypropylene (PP) may be used as long as they can exhibit creep resistance. Polyolefins including polyethylene (PE), polyamides (PA), and the like can be applied. Polyesters, particularly polyethylene terephthalate, is preferred because of the moldability and economy of the container.
As the size of the synthetic resin container 2, one having a capacity of 10 liters to 200 liters can be applied. Containers in this range are generally used for beverages and the like, and not only manufacturing techniques including blow molding but also filling techniques described later have been established. For example, a diameter of 30 cm, a height of 35 cm, and about 100 liters is applied.

Examples of the algae 11 cultured in the synthetic resin container 2 include Botryococcus brownie, Aurantiochytrium, Euglena, Chlorella, Sprulina, Dunaliea, Hematococcus, Nannochloropsis, Pseudocollistis and the like.
The liquid medium 12 is a mixture of nutrients in carbonated water, and as the nutrients, known carbohydrates, lipids, vitamins, minerals, and the like can be combined. Use of crop waste such as molasses is preferable from the viewpoint of economic efficiency and non-competition with food production in addition to nutrients.
Then, algae, nutrients and carbonated water are mixed so that the algae is 0.01 to 1 g / l, the carbohydrate is 5 to 50 g / l, the CO ₂ concentration is 0 to 10 g / l, and the pH is 3 to 10. And fill the plastic container. For this filling, the same equipment as that used to fill the beverage in the beverage container can be used. This filling system has established aseptic filling technology for beverages, and by utilizing this in the present invention, it is possible to prevent contamination of bacteria when filling algae into a synthetic resin container. When carbonated water is used as a base, an internal pressure of about 0.01 to 0.7 MPa acts on the synthetic resin container 2.

As the drift prevention means 3, a floating structure as shown in FIG. 2 can be constructed.
In the example of the floating structure 3 shown in FIG. 2, the synthetic resin containers 2 are assembled by being connected together by a large number of cords 31 such as wires, ropes, chains, etc., and the entire outside of the assembly of these synthetic resin containers 2. Is surrounded by a frame-like floating body 32, and the rope-like body 31 is fixed to the frame-like floating body 32, whereby a large number of synthetic resin containers 2 are held in the frame-like floating body 32. When the algae 11 grows by photosynthesis such as Botryococcus brownie, the synthetic resin containers 2 are preferably arranged in a plane inside the frame-like floating body 32. Moreover, it is good to give slack to the cord-shaped tool 31 between each synthetic resin container 2 so that it can move freely mutually. Then, the four corners of the frame-like floating body 32 are fixed to the seabed 5 by the fixing rope-like tool 33 so as not to flow into the ocean current.
2 and 3, reference numeral 6 indicates the sea surface.
In this embodiment, an example in which a floating structure is constructed as the drift prevention means 3 is shown, but the floating structure is not necessarily required.

As shown in FIG. 1, the algae culture apparatus 1 configured in this way is first filled with algae 11 and a liquid carbonic acid medium 12 in each synthetic resin container 2 and sealed with a cap 22. 2 is put on the ocean and installed in a state moored on the seabed 5 as a floating structure. In this state, the algae 11 are cultivated in each synthetic resin container 2 during a predetermined period.
In this case, since the culture is performed on the ocean or the like, it is an open system similar to the open bond method. However, each synthetic resin container 2 has the mouth portion 21a of the container body 21 storing algae and the like sealed with a cap 22. Thus, the environment is a closed system in which the algae 11 inside do not come into contact with the outside air. In addition, since carbonated water is used as the culture medium, the inside of the synthetic resin container 2 is at a positive pressure higher than the outside air due to carbon dioxide gas, and the sealing of the lid is momentarily impaired due to external impact or the like. Even if it exists, the invasion of outside air can be effectively prevented. Therefore, although it is an open system form, it can culture | cultivate with high quality without an impurity mixing like a closed system.

In addition, each synthetic resin container 2 is in a state of floating on the ocean, and a liquid carbonic acid medium or the like is enclosed therein, and shakes due to the influence of waves or the like, so the inside of the synthetic resin container 2 is agitated. For this reason, the algae 11 enclosed inside can be brought into contact with the fresh carbonic acid culture medium 12 to promote growth, which is efficient.
Furthermore, in the case of algae that proliferate by photosynthesis such as Botryococcus brownies, the transparent synthetic resin container 2 grows in the sun under sufficient sunlight.

And after leaving on the sea for a predetermined period, for example, two months, as shown in FIG. 1, the synthetic resin container 2 is collect | recovered, and fats and oils are extracted from algae and refine | purified. The obtained fats and oils can be used as products such as heavy oil. Moreover, the algal residue from which the fats and oils are extracted can be used for feed and the like. In the case of Botryococcus brownie, oil and fat are produced in vitro, so that the oil and fat are separated from the alga and can be easily recovered. Aulanthiochytrium is an algae produced in the body, which is refined from algae and recovers fats and oils.
The synthetic resin container 2 from which the algae has been collected is refilled with the algae 11 and the carbonic acid medium 12 and then reused as a part of the floating structure 1 after washing the inside. In this case, if some of the synthetic resin containers are damaged, only the synthetic resin container may be replaced with a new synthetic resin container 2, and other healthy synthetic resin containers may be reused as they are. it can.

  In the series of systems from filling algae etc. into the above synthetic resin containers to culturing, recovery, extraction and purification of fats and oils, excluding work such as filling and transportation to the ocean, recovery after cultivation, extraction and purification of fats and oils, etc. For example, since most of the entire process simply floats a synthetic resin container storing algae or the like on the ocean, no new input energy is required during the culture period. Therefore, coupled with the fact that it can be manufactured inexpensively as a culture device, the cost can be greatly reduced despite the fact that it is a closed culture system.

In addition, when recovering the synthetic resin container 2 from the ocean, after collecting all of them and extracting the oil and fat, etc., the used synthetic resin container 2 can be recycled and re-cultured with new algae. However, it is also possible to sequentially collect and re-cultivate the cells while changing the location at a plurality of locations. In this case, as shown in FIG. 2, it may be collected and re-cultured several times from the suspension on the ocean as a group, or suspended on the ocean in a state of being divided into a plurality of groups, collected for each group, You may make it re-culture.
FIG. 4 schematically shows a form in which synthetic resin containers are cultured in a plurality of groups, and are individually collected and re-cultured. In the example shown in FIG. 4, drift prevention means 3 _{1 to} 3 _n are provided for each group, and are arranged in an orderly manner on the ocean. In addition, a management facility 35 is provided on land, and as indicated by the arrows, it is installed and collected for each group. In the management facility 35, the synthetic resin container 2 is filled with algae and carbonic acid medium, and after culture Algae collection and oil and fat extraction are performed.
In this way, by collecting and re-culturing in a plurality of groups, it is possible to obtain a large amount of oil and fat continuously, which is suitable for commercial production.

In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
For example, in the above embodiment, the synthetic resin container storing algae or the like is suspended and cultured on the ocean, but may be a lake, a marsh, a river, or the like, not only on the water but also suspended in water. Is also possible.
As the drift prevention means, in addition to the embodiment, it is also possible to adopt means such as covering the whole of a large number of synthetic resin containers suspended on water or in water with a net.
An artificial outdoor pool may be constructed and placed on the water or in the water.
In addition, a blade extending in the radial direction or the like may be integrally formed on the outer surface of the synthetic resin container, and the blade can be subjected to pressure by waves on the ocean to increase the shaking of the synthetic resin container.
Furthermore, in the case of algae that grow by photosynthesis, artificial lighting may be provided by LEDs or the like.

DESCRIPTION OF SYMBOLS 1 Algae culture apparatus 2 Synthetic resin container 3 Drift prevention means 5 Sea bottom 6 Sea surface 11 Algae 12 Liquid culture medium 21 Container main body 21a Mouth part 22 Cap 31 Cable body 32 Frame-like floating body 33 Fixation cable body 35 Management facility

Claims (9)

  Algae and a liquid medium are enclosed in a synthetic resin container, and the algae are cultured in the synthetic resin container by suspending them in water or water in a state where a large number of the synthetic resin containers in which these are enclosed are assembled. Algae culture method.   2. The algal culture method according to claim 1, wherein a floating structure is constructed by connecting the synthetic resin containers, and the floating structure is moored in a floating state on the ocean.   The algal culture method according to claim 1 or 2, wherein the inside of the synthetic resin container in which the algae and the liquid medium are enclosed is set to a positive pressure with respect to the outside.   The algae culture method according to any one of claims 1 to 3, wherein a blow-molded polyester container is used as the synthetic resin container.   An algae culture apparatus comprising a large number of synthetic resin containers in which algae and a liquid medium are enclosed, and drift prevention means for holding these synthetic resin containers in an aggregated state.   6. The algae culture method according to claim 5, wherein the synthetic resin container is a blow molded polyester container.   The algal culture apparatus according to claim 5 or 6, wherein the synthetic resin container has an internal volume of 10 liters to 200 liters.   The algae culture apparatus according to any one of claims 5 to 7, wherein the synthetic resin container is formed of a light transmissive material. The algae culture apparatus according to any one of claims 5 to 8, wherein a floating structure that is moored in a state of being floated on the ocean by connecting the synthetic resin containers is constructed.

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