JPH04287678A - Bioreactor - Google Patents

Abstract

PURPOSE:To improve solar light utilizing efficiency in a bioreactor in which algae are proliferated. CONSTITUTION:A flow path of culturing liquid is composed of a tubular wavelength converter 7. In an to increase further growth effect, a cold filter 6 is arranged in the upper part of the wavelength converter 7 and a reflecting plate 2 in the lower part thereof and a twist plate 8 in the culturing liquid flow path. Thereby light with wavelength effective for culture of algae among incident solar light into the bioreactor is allowed to impinge in nearly uniform light intensity from whole circumference of the culturing liquid flow path.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bioreactor for growing algae using light from the sun, an artificial light source, or the like.

0002

BACKGROUND OF THE INVENTION Plants such as algae carry out photosynthesis under light and produce various useful substances through carbon dioxide assimilation. However, the sunlight utilization efficiency of plants in their natural state is 2%.
This efficiency is relatively low, and it is necessary to increase this efficiency for industrialization. Therefore, the development of bioreactors that can set optimal conditions for culturing algae is attracting attention. However, the light spectrum from light sources such as sunlight or artificial light is not necessarily the optimal light spectrum for culturing algae. Therefore,
If the light spectrum from the light source can be brought closer to the light spectrum optimal for culturing algae, the light utilization efficiency of the bioreactor can be increased. Furthermore, since algae are cultivated at high density in bioreactors, it is necessary to make light as uniform as possible throughout the algae in the water. However, the growth rate of algae is saturated at a light intensity (1/10 to 1/3 of the solar radiation) that is considerably lower than the solar radiation (~1kW/m2), so in order to effectively utilize sunlight, It is necessary to efficiently disperse the light to a saturation light intensity level before it enters the algae.

Phosphors are known as substances that have the function of converting the wavelength of light. That is, the phosphor absorbs light in a specific wavelength range and emits light having a spectrum on the longer wavelength side than the light corresponding to the absorption spectrum. Solar cells, light concentrators, greenhouses, etc. that utilize the wavelength conversion function of this phosphor are known.

[0004] In a conventional solar cell using a phosphor, as described in Japanese Patent Laid-Open No. 152170/1982, the phosphor is used as a component of the light incident on the transparent plastic (wavelength conversion layer) in which the phosphor is dissolved. The structure was such that the light corresponding to the absorption spectrum was converted into light with a longer wavelength, and this light, along with the remaining incident light, was converted into electrical energy by an optically connected solar cell. This increases the wavelength components suitable for solar cells and improves the efficiency of converting incident light into electrical energy.

[0005] In addition, in conventional greenhouse apparatuses using phosphors, as described in Japanese Patent Application Laid-open No. 147056/1982, a transparent glass plate is provided with a transparent plate on the back and front surfaces of the glass plate, which is transparent except for light corresponding to the absorption spectrum. A layer of wavelength converter (phosphor) was provided to constitute a light condensing plate (wavelength conversion layer), and the wavelength conversion layer constituted the roof of the greenhouse. This converts a portion of the light that enters the roof into longer wavelength light, focuses the light using total internal reflection at the wavelength conversion layer interface, and directs the light extracted from a portion of the wavelength conversion layer to an optical fiber, etc. At the same time, among the remaining incident light and the wavelength-converted light, the light that enters the inside of the greenhouse without satisfying the total internal reflection condition is allowed to enter the plants inside the greenhouse.

[0006]

[Problems to be Solved by the Invention] In the structure of a conventional solar cell using a phosphor, the solar cell is optically connected to the back surface of a flat wavelength conversion layer facing the direction of light incidence. Therefore, if you simply replace solar cells with a culture solution containing algae, sunlight and wavelength-converted light will enter from only one side, so the algae near the surface of the wavelength conversion layer will receive excessive light above the saturation light intensity. incident with intensity. However, this light is absorbed and scattered near the surface of the culture solution, and the light intensity that enters most of the algae dispersed in the water is insufficient. Therefore, there is a problem in that only a portion of the incident light can be used for culturing algae.

[0007] Even in conventional greenhouse equipment using phosphors, as with the conventional technology, light enters only the plants facing the sun, making it difficult to distribute and enter the light as uniformly as possible over the entire plant. Met. Further, in this prior art, the main focus is on condensing wavelength-converted light. Therefore, the light that has not been wavelength converted enters the greenhouse,
Only a portion of the wavelength-converted light entered the greenhouse.

[0008] Therefore, an object of the present invention is to provide a bioreactor that can efficiently disperse and inject light from a light source and light whose wavelength has been partially converted into the entire algae in the water. That's true.

[0009]

[Means for Solving the Problems] In order to efficiently disperse and inject light from a light source and a portion of the light whose wavelength has been converted into the entire algae in the water, the bioreactor element of the present invention uses transparent plastic. For example, a culture solution flow path was constructed so as to surround the culture solution with a tubular wavelength converter made of an acrylic resin and an organic phosphor dissolved therein. To further improve performance, a torsion plate was placed inside the culture medium flow path. Further, a reflecting plate having a roughly semicircular cross section was placed below the bioreactor element, and a plurality of bioreactor elements were connected in series or in parallel to form a bioreactor. In addition, an infrared reflection filter was placed on the sunlight incident side of this bioreactor.

0010

[Function] Characteristic functions and effects of the bioreactor of the present invention will be explained below.

Of the sunlight incident on the upper part of the tubular wavelength converter, light corresponding to the absorption spectrum of the phosphor is converted into light with a longer wavelength within the wavelength converter. Other sunlight passes through the wavelength converter and enters the culture solution. The wavelength-converted light is isotropically emitted from the phosphor, and is emitted from the interface on the sunlight incident side (the outer surface of the tubular wavelength converter) and the interface with the culture medium (
Depending on the angle of incidence on the inner surface of the tubular wavelength converter,
(1) Light escaping from the surface on the sunlight incident side, (2
) The light that is totally reflected at the interface (surface) on the sunlight incident side, (
3) Light that passes through the interface between the wavelength converter and the culture solution and enters the culture solution, and (4) Light that is totally reflected at the interface between the wavelength converter and the culture solution. Of these lights (2)
and (4) are repeatedly totally reflected and dispersed within the wavelength converting body. During this process, the direction changes due to minute defects within the wavelength converter, or due to minute irregularities on the interface, light that no longer satisfies the conditions for total reflection exits from the interface. At this time, the refractive indices of air, acrylic resin (base material of the wavelength converter), and water (base material of the culture solution) are 1.00, 1.49, and 1.49, respectively.
1.33, most of the light no longer satisfies the total reflection condition at the interface with the culture solution and enters the culture solution flow path. This allows the wavelength-converted light to reach the culture medium flow path where sunlight does not directly enter.
It becomes possible to efficiently disperse the liquid and make it enter the culture liquid flow path.

[0012] Since the torsion plate in the culture solution flow path stirs the flow of the culture solution, even if there is a light intensity distribution in the circumferential direction of the culture solution flow path, the algae in the culture solution absorb light equally. It acts to help give people the opportunity to do something.

[0013] The reflector plate, which has a roughly semicircular cross section and is placed below the bioreactor element, reflects sunlight and allows sunlight to enter from the bottom of the culture medium flow path. To make the light intensity distribution in the circumferential direction more uniform.

[0014] The infrared reflection filter placed on the sunlight incident side of the bioreactor removes infrared rays unnecessary for the growth of algae from sunlight. This prevents the culture solution from being heated more than necessary.

[0015]

[Embodiment] An embodiment of the present invention will be explained below with reference to FIG. FIG. 1 is a plan view of the bioreactor of the present invention. In FIG. 1, a plurality of bioreactor elements 1 are arranged in parallel inside a case 5 provided with a cold filter 6 as a cover, and both ends of each bioreactor element 1 are connected to an inlet header 4 and an outlet header 3, respectively. ing. In addition, on the underside of each bioreactor element 1,
Reflection plates 2 each having a semicircular cross section are arranged.

FIG. 2 is a sectional view taken along line A-A of the bioreactor shown in FIG. In FIG. 2, the bioreactor element 1 includes a cylindrical wavelength converter 7 and a torsion plate 8 disposed inside the wavelength converter 7.
It constitutes a flow path for a culture solution through which a culture solution 9 containing algae and carbon dioxide gas necessary for culturing the same flows. The cylindrical wavelength converter 7 is made of, for example, RED- as a phosphor.
It is obtained by forming an acrylic resin into which 300 (trade name) is dissolved into a tubular shape.

The operation of the present invention will be explained below with reference to FIG. Of the sunlight that enters the bioreactor, light with a wavelength of 700 to 800 nm or more that is unnecessary for the growth of algae is removed by reflection by the cold filter 6, and only visible light is transmitted. This can prevent the bioreactor element 1 from being heated unnecessarily. The transmitted visible light either directly enters the wavelength converter 7 having a circular tubular shape, or is reflected by the reflector 2 and enters the wavelength converter 7 . As a result, sunlight enters from the lower side as well, so that the light intensity distribution in the circumferential direction of the wavelength converter 7 is made uniform. However, it is difficult to make the light intensity distribution uniform with this alone, and some shadow areas remain.

Of the light incident on the tubular wavelength converter 7, light with a wavelength of 500 to 600 nm, which has a small contribution to algae growth, is absorbed by the phosphor. The other light enters the culture solution 9. The light absorbed by the phosphor has a wavelength 6 that is effective for algae growth.
It is converted into light with a wavelength of 00 to 650 nm and is emitted. This synchrotron radiation is emitted isotropically, and depends on the size of the incident angle to the interface on the sunlight incident side (the outer surface of the wavelength converter 7) and the interface with the culture solution 9 (the inner surface of the wavelength converter 7). , (1) light escaping to the outside from the surface on the sunlight incident side, (2) light totally reflected at the interface (surface) on the sunlight incident side, (3) the interface between the wavelength converter 7 and the culture solution 9. The light is divided into (4) light that passes through and enters the culture solution 9, and (4) light that is totally reflected at the interface between the wavelength converter and the culture solution. Of these lights (2) and (4)
is repeatedly totally reflected and dispersed within the wavelength converter 7. During this process, the direction of the light changes due to minute defects in the wavelength converter 7, or light that no longer satisfies the total reflection condition due to minute irregularities at the interface exits from the interface. At this time, the refractive indexes of air, acrylic resin (base material of wavelength converter 7), and water (base material of culture solution) are 1.00, 1.49, and 1.00, respectively.
33, most of the light no longer satisfies the total reflection condition at the interface with the culture solution and enters the culture solution flow path. As a result, the wavelength-converted light reaches the shaded wavelength converter portion, so that the light intensity distribution incident on the culture solution in the wavelength converter 7 is made more uniform.

The torsion plate 8 in the medium flow path helps to give the algae in the medium flow path an equal opportunity to absorb light by agitating the flow of the medium.

FIG. 3 is a sectional view of a bioreactor showing another embodiment of the present invention. In FIG. 3, the bioreactor element 21 disposed between the cold filter 26 and the reflection plate 22 is composed of an elliptical tubular wavelength converter 27 and a torsion plate 28 disposed inside it, and is suitable for algae and its cultivation. It constitutes a culture solution flow path through which a culture solution 29 containing necessary carbon dioxide and the like flows. The basic operation is the same as that of the embodiment shown in FIG. 2, but in this embodiment, the cross-sectional shape of the wavelength converter 27 is a vertically long ellipse. Thereby, the intensity of incident light per unit surface area of the wavelength converter 27 can be reduced to the extent necessary for culturing algae, so that sunlight can be used effectively.

FIG. 4 is a cross-sectional view of a bioreactor element showing another embodiment of the invention. In the figure, a tubular wavelength converter 37 is constructed by filling alcohol 43 in which a phosphor is dissolved into the gap between a double tube made up of a transparent outer tube 41 and an inner tube 42 made of glass or the like. . The culture solution 39 flows inside the inner tube 42 . As a result, even if the phosphor deteriorates, the alcohol 43 that has dissolved the phosphor can be used.
Just replace it.

[0022]

According to the present invention, light from the sun and light whose wavelength has been partially converted can be efficiently dispersed and made incident on the algae in the culture solution.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a bioreactor showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA in FIG. 1;

FIG. 3 is a sectional view of a bioreactor showing another embodiment of the present invention.

FIG. 4 is a sectional view of a bioreactor showing still another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1...Bioreactor element, 2...Reflector, 6...Cold filter, 7...Wavelength converter, 8...Twisted plate, 9...Culture solution.

Claims (6)

[Claims] Claim 1: A wavelength converter in which a phosphor is dissolved in a transparent material such as plastic or an organic solvent, which is used in a bioreactor that uses sunlight or other light to cultivate plants such as algae dispersed in a culture solution. A bioreactor characterized in that a culture solution flow path is configured to surround a culture solution. 2. The bioreactor according to claim 1, wherein a flow agitator such as a torsion plate is arranged in the flow path of the culture solution. 3. The bioreactor according to claim 1, further comprising a reflecting plate disposed below the culture fluid channel. 4. In claim 1, the inside of the inner tube of the transparent double tube is used as the culture medium flow path, and a liquid solvent in which a phosphor is dissolved is placed between the outer tube and the inner tube for wavelength conversion. A bioreactor made up of a body. 5. A bioreactor comprising a plurality of the bioreactors according to claim 1, 2, 3, or 4 connected in series or in parallel. 6. The bioreactor according to claim 5, wherein an optical filter having an infrared ray removal function is disposed on the sunlight incident side of the bioreactor.