JP6110190B2 - Microalgae culture method and culture control apparatus - Google Patents

Description

  The present invention relates to a method for culturing microalgae and a culture control apparatus.

In recent years, in order to suppress global warming, reduction of the emission amount of carbon dioxide, which is one of the greenhouse gases, has been an issue.
As a means for reducing carbon dioxide, there is a method using photosynthesis of plants. Among plants, microalgae in particular have attracted attention as a promising means for reducing carbon dioxide because they have a higher growth potential than terrestrial plants (see, for example, Patent Document 1).

  For example, a process for synthesizing fuel while suppressing carbon dioxide emissions at power plants and factories using microalgae that generates and accumulates oil components internally is being studied, as well as carbon dioxide using photosynthesis of microalgae. Effective utilization of carbon has been studied.

  By the way, in the cultivation of microalgae, a liquid in which microalgae stored in a culture vessel is dispersed in a culture medium (hereinafter sometimes referred to as “microalgae solution”) is irradiated with natural light or illumination light and carbon dioxide is irradiated. It is carried out by aerating a gas to be contained and causing photosynthesis of microalgae (see, for example, Patent Document 2). In this patent document 2, it is disclosed that light inhibition is prevented by irradiating microalgae intermittently with sunlight, thereby culturing efficiently. In this method, when the microalgae are grown to a predetermined amount, all the microalgae are collected and the culture of the microalgae is started again.

JP 2000-050861 A Special Table 2000-504924

  However, the growth rate of microalgae changes according to the ratio of the amount of microalgae to the microalgae solution (hereinafter sometimes referred to as “the concentration of microalgae”). If all of the cells are collected after they are grown, they cannot be cultured efficiently because there are both a low growth rate and a high growth rate. The growth rate of microalgae is also related to the amount of carbon dioxide absorbed by microalgae, and as a result, carbon dioxide cannot be reduced efficiently. For this reason, it is desired to reduce carbon dioxide more efficiently by culturing microalgae with a high carbon dioxide absorption.

  Then, an object of this invention is to provide the culture method and culture | cultivation control apparatus of a micro algae which can reduce a carbon dioxide efficiently.

  In order to solve the problems as described above, the method for culturing microalgae according to the present invention is acquired in an image acquisition step of acquiring an image of a solution in which microalgae are dispersed in a medium, and the image acquisition step. A color information extraction step for extracting information about the color of the measurement method microalga solution from the image, and a measurement method when the information about the color of the measurement method microalga solution extracted in this color information extraction step satisfies a predetermined condition Extraction of the microalgae solution and measurement method The method comprises a replacement step of replenishing the medium to the microalgae solution.

  In the method for culturing microalgae, the predetermined condition may be to indicate that the microalgae solution includes information regarding a color when the amount of carbon dioxide absorbed per unit time in the microalgae solution is maximum.

  Further, the culture control apparatus for microalgae according to the present invention includes an image acquisition unit that acquires an image of a solution in which microalgae is dispersed in a medium, and a measurement method microalgae solution from the image acquired by the image acquisition unit. When the information extracted by the color information extraction unit and the information extracted by the color information extraction unit satisfy a predetermined condition, the measurement method extracts the microalgae solution and the measurement method extracts the medium from the microalgae solution. And an exchange unit for instructing replenishment.

  According to the present invention, since the microalgae can be continuously cultured in a state where predetermined conditions are satisfied, carbon dioxide can be continuously absorbed by the microalgae at a predetermined rate, and as a result, carbon dioxide can be more efficiently produced. Can also be reduced.

  In addition, according to the present invention, since the microalgae can be continuously cultured in a state in which the time change of the carbon dioxide fixation amount in the microalgae solution is maximum, carbon dioxide is continuously absorbed by the microalgae at the highest rate. As a result, carbon dioxide can be reduced most efficiently.

FIG. 1 is a graph showing the time change of the concentration of microalgae. FIG. 2 is a flowchart showing the procedure of the method for culturing microalgae according to the embodiment of the present invention. FIG. 3 is a graph showing temporal changes in the total organic carbon content of microalgae corresponding to FIG. FIG. 4 is a graph showing temporal changes in color information extracted from an image of a microalgae solution corresponding to FIG. FIG. 5 is a diagram showing a configuration of a culture control apparatus for microalgae according to the second embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In addition, “algae” is a general term for organisms that perform photosynthesis, excluding terrestrial plants (moss plants, fern plants, seed plants). Of these, small algae that cannot be seen without using a magnifying glass. Algae are called “microalgae”. In the present specification, “microalgae” refers to algae having a size that can be dispersed in a medium such as water. So-called phytoplankton is an example of microalgae. A microalgae dispersed in a medium is called a “microalgae solution”.

  The microalgae solution (sample) is stored in a culture vessel made of a transparent material such as a flask. The microalgae are cultured by irradiating the culture vessel with natural light or illumination light and allowing a gas containing carbon dioxide to pass through to cause photosynthesis of the microalgae. Each embodiment of the present invention is directed to a solution of microalgae in such a cultured state.

  In addition, as a method for culturing microalgae, a batch method and a continuous method are known, but in each embodiment of the present invention, a continuous method is adopted. The reason for this will be described below.

Here, the batch type refers to the ratio of the amount of microalgae to the microalgae solution (hereinafter referred to as “the concentration of microalgae”) by preparing and culturing a microalgae solution in which a small amount of microalgae is dispersed in a medium. If the microalgae is sufficiently high or the target concentration is reached, all the microalgae solution is extracted from the culture vessel, and the microalgae solution in which a small amount of microalgae is dispersed is re-introduced into the culture medium. The solution is cultured every time.
On the other hand, the continuous type means that a microalgae solution is cultured, and when the microalgae concentration reaches a predetermined concentration, a part of the microalgae solution is extracted from the culture vessel and the same medium as the microalgae solution is extracted. By replenishing the culture vessel, the culture is continuously performed while maintaining the same level of microalgae.

  As shown in FIG. 1, the microalgae are called the logarithmic growth phase when the microalgae concentration is low, and the microalgae grow exponentially. However, as the microalgae concentration increases, the growth rate slows down. At a certain concentration, the growth of microalgae stops. For this reason, in the batch system, a certain amount of carbon dioxide can be absorbed by the microalgae in one culture, but changes until the growth rate of the microalgae reaches a certain amount. As will be described later, since the concentration of microalgae is related to the amount of carbon dioxide absorbed by microalgae, the amount of carbon dioxide absorbed also changes during the cultivation process. As a result, carbon dioxide is efficiently absorbed into microalgae. It will be difficult to absorb. On the other hand, in the continuous type, since the microalgae can be continuously cultured in a constant state such as a constant concentration, the microalgae can be cultured at a constant growth rate, and as a result, carbon dioxide is also absorbed at a predetermined rate. Can continue to. At this time, the state of microalgae is detected, and the microalgae is extracted most efficiently by extracting the microalgae solution and replenishing the medium so that the state of highest carbon dioxide absorption is maintained. Can be absorbed.

[First Embodiment]
A method for culturing microalgae according to the first embodiment of the present invention will be described. As described above, the method for culturing microalgae according to the present embodiment cultivates the microalgae solution stored in the culture vessel in a continuous manner. As shown in FIG. An image acquisition step S1 for acquiring an image of the solution; (2) a color information extraction step S2 for extracting information on the color of the microalgae solution from the acquired image; and (3) a color of the extracted microalgae solution. Determination step S3 for determining whether the information regarding the predetermined condition is satisfied, and (4) if it is determined that the information regarding the color of the extracted microalgal solution color satisfies the predetermined condition, It comprises an exchange step S4 for exchanging the solution.

<Culture method>
Next, each step of the culture method according to the present embodiment will be described in detail.

(1) Image acquisition step S1
The image acquisition step S1 is a step of acquiring an image obtained by imaging a microalgae solution cultured in a culture vessel with an imaging device such as a digital camera.

(2) Color information extraction step The color information extraction step S2 is a step of extracting information (color information) relating to the color of the image acquired in the image acquisition step S1.

  As the color information of the image, parameter values constituting various color spaces can be used. In the present embodiment, R and G of RGB (or RGB color model) “red (R: Red)”, “green (G: Green)”, and “blue (B: Blue)” are used. Such color information is obtained by performing image processing on image data captured by an imaging device by a computer that functions as an image processing device by installing image processing software such as Photoshop (registered trademark). Can be obtained.

To extract color information, first, on the monitor, specify a predetermined area (part or all of the part where the microalgae solution is reflected) in the acquired image. For each pixel in the designated area, the gradation of each R or G color component (for example, 256 levels from 0 to 255) is acquired. Next, R or G gradation histograms of pixels in the area are acquired. Then, the average value of the gradations of the R or G color components is calculated as the color information of the image.
In the present embodiment, the average value is obtained and used to determine the concentration of microalgae described later. However, it goes without saying that not only the average value but also the median value, the maximum value, or the like may be used as the color information.

(3) Determination Step The determination step S3 determines whether or not the microalgae solution cultured in the culture vessel satisfies a predetermined condition from the information (color information) regarding the color of the image extracted in the color information extraction step S2. It is a step which determines.
Prior to this determination step S3, predetermined conditions are obtained in advance by a method described later. In the present embodiment, the predetermined condition includes a gradation value of an R or G color component as in the color information extracted in the color information extraction step S2, as will be described later.
The determination is made by comparing the color information extracted in the color information extraction step S2 with a predetermined condition. If the color information reaches a predetermined condition, it is determined that the microalgae solution cultured in the culture vessel satisfies the predetermined condition, and the exchange step S4 is executed. On the other hand, if the color information does not reach the predetermined condition, it is determined that the microalgae solution cultured in the culture container does not satisfy the predetermined condition, and the process returns to the image acquisition step S1.

≪How to obtain a predetermined condition≫
The predetermined condition is composed of information relating to the color as in the color information extracted in the color information collecting step S2.

FIG. 3 is a graph showing the time change of the total organic carbon (TOC) of the microalgae corresponding to FIG. Here, the TOC indicates the total amount of organic matter that can be oxidized in water in the amount of carbon, and corresponds to the amount of carbon dioxide absorbed by the microalgae.
The slope of the graph of FIG. 3, that is, the amount of carbon dioxide absorbed by the microalgae per unit time gradually increases from the time point a to the time point b, reaches a maximum value at the time point b, and Since then, it has gradually decreased. As described above, the amount of carbon dioxide absorbed per unit time value of microalgae varies according to the concentration of microalgae, as does the amount of microalgae grown. According to FIG. 3, it is understood that the amount of carbon dioxide absorbed by the microalgae is the maximum at the point “b”.
1, 3, and 4 indicate simultaneous points.

FIG. 4 is a graph showing temporal changes in color information extracted from the image of the microalgae solution corresponding to FIG. Here, the color information shown in FIG. 4 is an average value of the gradations of the R and G color components extracted by the same procedure as that described in the color information extraction step S2.
According to FIG. 4, it can be seen that the gradations of R and G approach 0 as time passes. Thus, the color information of the image of a microalga changes according to the density | concentration of a microalgae similarly to the growth amount of a microalgae and the absorption amount of a carbon dioxide. Therefore, when the color information of the microalgae solution in a desired state is acquired in advance as a predetermined condition and the color information of the microalgae solution in the culture container reaches the predetermined condition, the culture container is replaced by an exchange step S4 described later. Remove the solution and replenish the medium. Thereby, carbon dioxide can be continuously absorbed by the microalgae at a predetermined ratio.
In the present embodiment, the predetermined condition is the color information of the microalgae solution at the time point b shown in FIG. At the time of the symbol b, the amount of carbon dioxide absorbed by the microalgae is the maximum as described above. Therefore, since carbon dioxide can be absorbed by microalgae at the highest rate, carbon dioxide can be reduced most efficiently as a result.

(4) Exchange step
The replacement step S4 is a step of replacing the microalgae solution in the culture container when it is determined in the determination step S3 that the microalgae solution cultured in the culture container satisfies a predetermined condition.
The exchange of the microalgae solution is performed by extracting a predetermined amount of the microalgae solution from the culture vessel and replenishing the culture vessel with the same amount of the medium as the predetermined amount. The amount of the microalgae solution to be extracted is appropriately set depending on the size and shape of the culture vessel, the growth rate of the microalgae, and the like.

  As described above, according to the present embodiment, it is possible to continue culturing microalgae in a state where predetermined conditions are satisfied, so that microalgae can be efficiently cultured. As a result, carbon dioxide can be continuously absorbed by the microalgae at a predetermined rate, so that carbon dioxide can be reduced more efficiently.

[Second Embodiment]
Next, a microalgae culture control apparatus according to a second embodiment of the present invention will be described with reference to FIG.

<Device configuration>
The culture control apparatus for microalgae according to the present embodiment is an apparatus that outputs an instruction to replace the solution based on an image of the microalgae solution stored in a culture vessel photographed by a camera. This device includes a computer hardware device including a CPU (Central Processing Unit) and a storage device, and a computer program for controlling various hardware devices.

In FIG. 5, the functional block diagram of the culture control apparatus of the micro algae concerning this Embodiment is shown.
The control device according to the present embodiment includes an interface unit 20 that can be connected to the camera 10 directly or via a network, a control unit 21 that controls the operation of the device, and an input / output composed of a keyboard, a mouse, a monitor, and the like. An interface unit 22 connected to the unit 30, a program storage unit 23 storing a computer program for operating the computer as a culture control device for microalgae, and an image captured by the camera 10 and captured via the interface unit 20 An image storage unit 24 for storing the color information, a color information storage unit 25 for storing the color information of the image extracted by the color information extraction unit 21a described later, a condition storage unit 26 for storing predetermined conditions, and these components And a bus 27 as a path for data and control information between them.

  Here, the control unit 21 extracts the color information of the image captured in the image storage unit 24 by the computer program stored in the program storage unit 23 and stores it in the color information storage unit 25. An exchange unit 21b for instructing the exchange of the microalgae solution photographed by the camera 10 based on the color information stored in the color information storage unit 25 and the predetermined condition stored in the condition storage unit 26. It is out.

<Operation of the device>
Using the control device 3 described above, the culture of the microalgae solution stored in the culture vessel can be controlled as follows.

First, the camera 10 photographs a storage tank in which microalgae are cultured. The camera 10 is a device that outputs, as image data, parameter values (for example, luminance signals for RGB) constituting a color space for each pixel.
Such a camera 10 may be built in the microalga concentration determination device and may be always connected to the interface unit 20, or may be separate from the microalga concentration determination device, such as a commercially available digital camera. . In the case of a separate body, the image data is transmitted to the interface unit 20 via a network such as a cable or the Internet.
Data of an image photographed by the camera 10 is transferred to the image storage unit 24 via the interface unit 20.

Next, the color information extraction unit 21 a extracts color information from the image stored in the image storage unit 23. As this color information, values of parameters constituting various color spaces can be used. In the present embodiment, as in the first embodiment, among the RGB parameters of the RGB color space model, The detailed description is omitted as the average value is extracted from the R or G gradation.
The color information is extracted by displaying an image stored in the image storage unit 24 on the monitor (input / output unit) 30, allowing the user to specify an area from which the color information is to be extracted, and extracting the color information from this area. Also good. In this case, the user operates a mouse or the like constituting the input / output unit 30 to designate an area in which microalgae appear in the image as an area where color information should be extracted.
The color information extracted in this way is stored in the color information storage unit 25.

When the color information is extracted in this way, the exchange unit 21b compares the color information stored in the color information storage unit 25 with the predetermined condition stored in the condition storage unit, and the color information is determined to be predetermined. Detect whether the condition is reached.
When the color information reaches a predetermined condition, the exchanging unit 21b instructs to remove a predetermined amount of the microalgae solution from the culture container and to replenish the culture container with the same amount of the medium. put out. This instruction may be performed by, for example, displaying a message indicating the instruction on the monitor (input / output unit) 30 or outputting a control signal indicating the instruction to a device that automatically performs the replacement. Good. When displaying a message, a user exchanges microalgae based on the message. When outputting the control signal, the apparatus automatically changes the microalgae based on the control signal.
On the other hand, if the color information does not reach a predetermined condition, the exchanging unit 21b does not output an instruction for exchanging microalgae.

  As described above, according to the present embodiment, it is possible to continue culturing microalgae in a state where predetermined conditions are satisfied, so that microalgae can be efficiently cultured. As a result, carbon dioxide can be continuously absorbed by the microalgae at a predetermined ratio, so that carbon dioxide can be efficiently reduced.

  In the first and second embodiments described above, the case where the color information and the predetermined condition are composed of an average value of any one of R and G is described as an example. You may make it consist of both.

  In the present embodiment, the RGB parameter value of the RGB color space model has been described as an example of color information. However, another color space model may be used instead of the RGB color space.

  The present invention can be applied to various systems for culturing plants dispersed in a solution such as microalgae.

  DESCRIPTION OF SYMBOLS 10 ... Camera, 20 ... Interface part, 21 ... Control part, 21a ... Color information extraction part, 21b ... Exchange part, 22 ... Interface part, 23 ... Program storage part, 24 ... Image storage part, 25 ... Color information storage part, 26 ... Condition storage unit, 27 ... Bus, 30 ... Input / output unit.

Claims (2)

An image acquisition step of acquiring an image of a microalgae solution, which is a solution in which microalgae are dispersed in a medium;
A color information extraction step of extracting gradation value of the color component of the solution of the microalgae from the image acquired in the image acquisition step,
Gradation values of the color components of the solution of the microalgae extracted by the color information extraction step, a color component when the absorption amount of carbon dioxide per unit time in the previously obtained solution of the microalgae has is maximum reach the gradation value Then, the method for culturing microalgae, characterized in that it comprises an interchangeable performing a replenishment of the medium with the extraction of a solution of microalgae to a solution of the microalgae. An image acquisition unit for acquiring an image of a microalgae solution, which is a solution in which microalgae are dispersed in a medium;
A color information extraction unit that extracts gradation value of the color component of the solution of the microalgae from the image acquired by the image acquisition unit,
Gradation values of the color components of the solution of the microalgae extracted by the color information extraction unit, a color component when the absorption amount of carbon dioxide per unit time in the previously obtained solution of the microalgae has is maximum reach the gradation value Then, the culture control apparatus of microalgae, characterized in that it comprises an interchangeable unit for instructing the replenishment of the medium to the solution of the microalgae and extraction of the solution of the microalgae.