Chemistry: molecular biology and microbiology – Apparatus – Bioreactor
Reexamination Certificate
1999-06-17
2001-09-11
Beisner, William H. (Department: 1744)
Chemistry: molecular biology and microbiology
Apparatus
Bioreactor
C435S294100, C047S001400
Reexamination Certificate
active
06287852
ABSTRACT:
TECHNICAL FIELD
This invention relates to a photosynthetic culture system which fixes carbon dioxide by photosynthetically culturing and growing algae, plant microorganisms or the like.
BACKGROUND ART
Fossil fuels such as coal, oil and natural gas recently used in thermal power plants etc. release a vast amount of carbon dioxide into the atmosphere by burning. Increase of the released carbon dioxide in the atmosphere will deteriorate global environment by causing global warming etc., in addition, it will significantly affect the human society through the occurrence of natural disaster and heavy damage of crops, because increase of carbon dioxide in the atmosphere is the cause of a frequent drought, heavy rain and floods.
Thus, the development of the technology has been long-awaited which can fix carbon dioxide with less energy to decrease the amount of carbon dioxide released into the atmosphere. And as a simple, safe and effective method, a method has been investigated and is about to be utilized to fix carbon dioxide in the atmosphere using photosynthesis of plant microorganisms which is caused by irradiation of sunlight etc. However, in the construction of the conventional photosynthetic culture systems using plant microorganisms, since their culture baths need to ensure a certain volume of fluid, after photosynthesis proceeds to some extent, light required for photosynthesis does not reach the whole solution sufficiently. Therefore, methods have been used to make photosynthetic culture baths shallow or stir the fluid in the bath so that light will reach the whole solution.
For example, the amount of carbon dioxide in burning gas released from thermal power plants is as vast as about 5000 t/day at 500000 kW output power of burning natural gas, and when burning coal or oil, carbon dioxide emission will be further increased. In such a situation, in order to fix carbon dioxide released from thermal power plants, the systems which are as compact as possible and need less energy for the fixation are desirable. In order to solve these problems, improvements are required in the carbon dioxide fixing technology which are now in use globally such as enhancement of the carbon dioxide fixing ability of photosynthetic culture baths and systems including an optical system, enhancement of efficiency, increase of controllability of the products of photosynthetic reaction.
However, in view of the fact that an effective depth of the culture bath for photosynthesis is only several cm, one of the above methods, in which photosynthetic culture baths are made shallow, has a problem that the area of the photosynthetic culture systems must be extremely large-scale in order to ensure sufficient volume of culture solution. And the other method, in which the fluid is stirred, has also a problem that the whole culture bath is not made good use of since the fluid always subjected to photosynthesis is restricted within the limits where light can reach.
Further, in the conventional photosynthetic culture baths utilizing natural sunlight, since the surface of the solution which is a light-receiving surface is irradiated with an intensive sunlight, light intensity more than needed is wasted and it causes some troubles. In addition, with the progress of photosynthesis, the number of the cells is increased, which prevents light from reaching the depths of the fluid.
DISCLOSURE OF THE INVENTION
In light of these problems of the prior art, the purpose of the present invention is to provide a photosynthetic culture system and a collective photosynthetic culture system which allow to control the waste of optical energy, to make good use of the whole culture bath, and to control the increase of their installation area even when ensuring a sufficient volume of culture solution.
In order to cope with the foregoing problems and subjects, the present applicants propose the present invention, based on the basic and scientific study on photosynthetic media, the discovery of the photosynthetic media having good carbon dioxide fixing ability, a good knowledge of operation in a thermal power plant and a deep knowledge of carbon dioxide emission and its fixation, which will realize the introduction of photosynthetic media having the good carbon dioxide fixing ability as well as the introduction of the optimum environment to promote efficiency of photosynthesis and has the features described below.
The photosynthetic medium used in the present invention is, for example, Euglena gracilis which are plant microorganisms.
With the progress of photosynthesis, the number of the photosynthesized cells is increased, which prevents light from reaching the depths of the fluid. Therefore, the thickness of the culture solution is decreased in the direction in which light travels. In addition, in order to eliminate the waste of energy due to an excess of the natural sunlight irradiation over the required amount, the area of the natural sunlight-receiving surface is effectively expanded and the light is conducted to the light-receiving culture surface via the natural sunlight-receiving surface. The natural sunlight-receiving surface and the light-receiving culture surface are arranged to have a rectangular relationship.
The present invention according to one aspect is a photosynthetic culture system comprising: a culture bath holding an fluid containing plant microorganisms, carbon dioxide supplying means for supplying carbon dioxide to the fluid in the culture bath, light-conducting means in the form of a flat plate placed oppositely to a light-receiving culture surface existing on the side of the culture bath, and light-receiving means mounted on the upper end surface of the light-conducting means, wherein the light-conducting means has the function of turning the incident light from the light-receiving means by substantially right angles to conduct the light uniformly to the light-receiving culture surface of the culture bath.
The present invention according to another aspect is a collective photosynthetic culture system, wherein more than one photosynthetic culture system according to are arranged so that the light-receiving culture surfaces of said culture baths will be in parallel to one another and the photosynthetic culture systems are connected to one another with a connecting pipe for supplying an fluid, a connecting pipe for transferring products, and a connecting pipe for supplying carbon dioxide.
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Japanese language search report for Int'l Appln No. PCT/P98/04575 dated Feb. 22, 1999.
English translation of Form PCT/ISA/210. Feb. 22, 1999.
Honami Nobuo
Kanai Kenji
Kondo Jiro
Miyatake Kazutaka
Nakano Yoshihisa
Beisner William H.
Matsushita Electric - Industrial Co., Ltd.
Ratner & Prestia
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