Chemistry: molecular biology and microbiology – Apparatus – Bioreactor
Patent
1996-07-09
1999-09-28
Beisner, William H.
Chemistry: molecular biology and microbiology
Apparatus
Bioreactor
47 14, 4352571, C12M 142, C12N 112
Patent
active
059587610
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a bioreactor for improved productivity of photosynthetic algae. More particularly, the invention is concerned with bioreactors and bioreactor systems for optical enhancement of photosynthetic productivity of algae.
2. Discussion of the Background
In the past decade, there has been considerable activity relating to production of photosynthetic microalgae for commercial purposes. Special industries aiming to produce health food, food additives, animal feed, biofertilizers and an assortment of natural products (most notably .beta.-carotene) have been established. Recently, microalgae have been suggested as a means to sequester carbon from the industry, and hydrogen producing algae as a source of energy.
It is known that algae productivity is limited by three major factors: light, nutrients and temperature. Historically, most efforts have been invested in developing the optimum nutrients for any specific algae. This included means to saturate the photosynthetic system with CO.sub.2. Still, temperature remains a major limiting factor in commercial, outdoor production. Optimal conditions for efficient production are usually selected in accordance with the climatic conditions prevailing in a chosen site. Yet, even in such sites, winter and night temperatures, as well as morning hour temperatures pose serious limitations to growth rates.
Under optimal temperature and nutrient conditions, the single most important factor in limiting productivity is light. In order to address this problem, open algae producing ponds are made as shallow as practically possible for improving the surface to volume ratio, and stirring is increased to reduce the time the algae stay in darkness, which, in concentrated cultures, is a few millimeters from the surface.
Attempts have also been made to grow algae in tubes, again increasing the surface to volume ratio and hence light conditions thereof. Conventional tubes, however, do not allow temperature control and the light is limited by ambient conditions. If light intensity is less than maximum and strong light attenuation with depth of culture occurs, limitations to photosynthetic activity are imposed.
Still further development has recently been made by growing algae in tubes in which special light guides (fiber optics) are inserted in the tubes. These fibers uniformly diffuse a large proportion of the light passing through them. A solar concentrator is used to concentrate solar light onto one end of the fibers. The fiber optics in this arrangement occupy a large proportion of the reactor's volume and a large proportion of the light is lost through the end of the fibers. Since the reactor itself is in the dark, the use of the solar concentrator results in very low light intensities per surface unit within the growth chamber. No temperature control is available in this system.
SUMMARY OF THE INVENTION
It is therefore a broad object of the present invention to ameliorate the disadvantage of the above-described known devices, and to provide a bioreactor in which the light regime therein is improved.
It is a further object of the present invention to provide a bioreactor in which the average light intensity reaching the algae is increased.
Still a further object of the present invention is to provide a bioreactor in which the spectral quality of the impinging light can be adjusted in accordance with specific requirements of an algae species which is produced.
Yet still a further object of the present invention is to provide a bioreactor in which the temperature prevailing inside the reactor can be adjusted and controlled.
In accordance with the present invention there is therefore provided a bioreactor for improved productivity of photosynthetic algae, comprising a tubular housing surrounding a tubular envelope located therein and defining a space therebetween to be filled with fluid, said housing and envelope being made of at least a translucent material, said housing and envelope having inlet and out
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patent: 4324068 (1982-04-01), Anthony
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English language translation of JP 4-287678, Jan. 1997.
English language translation of FR 2564854, Jan. 1997.
English Language Abstract of JP 58-51888,(1983).
Yakir Dan
Yogev Amnon
Beisner William H.
Yeda Research and Developement Co. Ltd.
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