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Online estimation of biomass, lipid and nitrate dynamic profile using innovative light evolution kinetic model in flat panel airlift photobioreactor for Botryococcus braunii under varying light conditions

Khichi, Shailendra Singh, Rohith, S., Gehlot, Kartik, Dutta, B.C., Ghosh, Sanjoy
Bioresource technology reports 2019 v.6 pp. 6-14
Botryococcus braunii, absorbance, absorption, biomass, kinetics, light intensity, light scattering, lipid content, lipids, microalgae, models, nitrates, photobioreactors
Light availability inside the photobioreactor is generally measured by the Lambert – Beer law. However, Lambert - Beer law assumptions are not valid at high cell density cultural conditions, because light scattering and differential absorption have significant impact on light transfer in photobioreactor. In this study Lambert – Beer law was modified by applying differential absorbance in flat panel photobioreactor. As light intensity fluctuate with location and age in the cultivation process, aconsolidated model based on Lambert – Beer law including temporal light evolution and microorganism growth is presented. The model was calibrated under specific light intensity of 133 μmol m−2 s−1 and validated using the experimental data of microalgae growth under varying light conditions of 174, 261 and 348 μmol m−2 s−1. Maximum biomass concentration, maximum lipid content and lipid productivity were 2.52 g dcw L−1, 19.76% and 114.92 mg L−1d−1 at 261 μmol m−2 s−1 light intensity respectively.