Kinetic characterization and modeling of a microalgae consortium isolated from landfill leachate under a high CO2 concentration in a bubble column photobioreactor

BACKGROUND: The determination of kinetic parameters and the development of mathematical models are of great interest to predict the growth of microalgae, the consumption of substrate and the design of photobioreactors focused on CO2 capture. However, most of the models in the literature have been developed for CO2 concentrations below 10%. RESULTS: A nonaxenic microalgal consortium was isolated from landfill leachate in order to study its kinetic behavior using a dynamic model. The model considered the CO2 mass transfer from the gas phase to the liquid phase and the effect of light intensity, assimilated nitrogen concentration, ammonium concentration and nitrate concentration. The proposed mathematical model was adjusted with 13 kinetic parameters and validated with a good fit obtained between experimental and simulated data. CONCLUSIONS: Good results were obtained, demonstrating the robustness of the proposed model. The assumption in the model of DIC inhibition in the ammonium and nitrate uptakes was correct, so this aspect should be considered when evaluating the kinetics with microalgae with high inlet CO2 concentrations.

Morphological and physiological photon flux influence under in vitro culture of apple shoots

The aim of the present study was to evaluate the growth and development of apple rootstock shoots submitted to different photon flux densities (7, 14, 21 and 60 µmol m-2 s-1) and three culture media. The best photon flux for maximizing growth, number of shoots and leaves was 14 µmol m-2 s-1, which also resulted in the highest values of chloroplastic pigments. On the other hand, the highest photon flux (60 µmol m-2 s-1) decreased significantly these parameters. Medium with reduced sucrose concentration did not affect the analyzed parameters, enabling an efficient multiplication of the cultivar with only 1 percent of sucrose.

O objetivo do presente estudo foi avaliar características de crescimento e desenvolvimento de brotações de macieira submetidas a diferentes densidades de fluxo de fótons (7, 14, 21 e 60 µmol m-2 s-1) e três meios de cultura. O melhor fluxo de fótons para maximizar o crescimento, número de brotações e de folhas foi de 14 µmol m-2 s-1, o qual também proporcionou os maiores valores de pigmentos cloroplastídicos. Por outro lado, alto fluxo de fótons (60 µmol m-2 s-1) diminuiu significativamente os parâmetros citados acima. O meio com concentração reduzida de sacarose não afetou os parâmetros analisados, possibilitando uma multiplicação eficiente desta cultivar com apenas 1 por cento deste carboidrato.