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    QIBEBT Announced a Novel Microalgal Mass Cultivation Technology
    Update time: 2012-11-28
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    The microalga was considered as the most potential feedstocks for sustainable biofuel industry. However, the commercialization of microalgal biofuel was heavily restrained by the conventional aqueous-suspended cultivation methods (open ponds and closed photobioreactors) due to the energy loss in water body and the huge water consumption during cultivation. For example, the outdoor biomass productivity for conventional open pond is only 7-20 gm-2d-1, which is far behind the theoretic maximum of >100 gm-2d-1. Meanwhile, the biomass density was generally <1 gL-1 so that the energy input for harvesting was almost unaffordable.
    Fig. 1 The schematic diagram of attached cultivation technology for microalgae (Image by Prof. LIU Tianzhong’s Group)
    To resolve these problems of huge water consumption as well as poor land usage efficiency, Prof. LIU Tianzhong, Dr. WANG Junfeng and their Algae Energy Resource Group, at Qingdao Institute of Bioenergy and Bioprocess Technology, proposed a novel ‘attached microalgal cultivation technology’, in which the algal cells were attached on some specific artificial supporting materials and kept in wet by supplying small amount of culture medium. Varieties of oleaginous microalgal strains, including green algae and diatoms from fresh water and sea water, accumulated high amount of biomass and oil under proper medium composition and CO2 concentration with this attached cultivation method according to a Chinese patent under examination (201010250866.X).

    Based on these findings, the research team also proposed a novel principle of photobioreactor design based on two strategies of solar dilution to increase the cultivation productivity. One is the solar dilution by increasing the illumination area and another is the light-dark cycle with proper frequencies. Totally 3 pieces of related Chinese patents of the photobioreactor structure are now under examinations (201210051552.6, 201210048910.8, 201210051158.2).

    The biomass production potential was further investigated under indoor and outdoor conditions with the novel designed photobioreactor. Results showed that biomass productivities of 60-120 and 50-80 gm-2d-1 were obtained under indoor and outdoor conditions, respectively, which were 300-500% higher than conventional open ponds. Additionally, the water requirement was potentially reduced 95% for this bioreactor, so that the contamination control and scale-up might be readily achieved in the future large-scale facilities (Bioresource Technology, 2013, 127: 216-222). This technology has been also successfully applied in the mass cultivation of other microalgae like Spirulina. The outdoor biomass productivity reached 50-60 gm-2d-1, a 400% increase compared with open ponds, indicating significant potentials of this attached cultivation technology in impelling the upgrade of traditional economic microalgal industry.

    Fig. 2 The biomass productivity of Scenedesmus obliquus under indoor (A) and outdoor (B) conditions (Image by Prof. LIU Tianzhong’s Group)

    To further prove the technology, Prof. LIU’s team is constructing an attached microalgal cultivation system in pilot level of 200 m2 for oleaginous and economic microalgae, which was supposed to be finished in the first quarter of 2013. The above reported novel microalgae mass cultivation technology development was financial support by Ministry of Science and Technology of China and Chinese Academy of Sciences.

    Prof. Dr. LIU Tianzhong
    Qingdao Institute of Bioenergy and Bioprocess Technology
    Chinese Academy of Sciences
    Phone: +86-(0)532-80662735
    Email: liutz@qibebt.ac.cn
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    Add: No.189 Songling Road, Laoshan District, Qingdao Postcode: 266101