Author(s): Chiu SY, Kao CY, Chen CH, Kuan TC, Ong SC,
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Abstract The microalga incorporated photobioreactor is a highly efficient biological system for converting CO2 into biomass. Using microalgal photobioreactor as CO2 mitigation system is a practical approach for elimination of waste gas from the CO2 emission. In this study, the marine microalga Chlorella sp. was cultured in a photobioreactor to assess biomass, lipid productivity and CO2 reduction. We also determined the effects of cell density and CO2 concentration on the growth of Chlorella sp. During an 8-day interval cultures in the semicontinuous cultivation, the specific growth rate and biomass of Chlorella sp. cultures in the conditions aerated 2-15\% CO2 were 0.58-0.66 d(-1) and 0.76-0.87 gL(-1), respectively. At CO2 concentrations of 2\%, 5\%, 10\% and 15\%, the rate of CO2 reduction was 0.261, 0.316, 0.466 and 0.573 gh(-1), and efficiency of CO2 removal was 58\%, 27\%, 20\% and 16\%, respectively. The efficiency of CO2 removal was similar in the single photobioreactor and in the six-parallel photobioreactor. However, CO2 reduction, production of biomass, and production of lipid were six times greater in the six-parallel photobioreactor than those in the single photobioreactor. In conclusion, inhibition of microalgal growth cultured in the system with high CO2 (10-15\%) aeration could be overcome via a high-density culture of microalgal inoculum that was adapted to 2\% CO2. Moreover, biological reduction of CO2 in the established system could be parallely increased using the photobioreactor consisting of multiple units.
This article was published in Bioresour Technol
and referenced in Journal of Membrane Science & Technology