Bioprocess strategies for enhancing the outdoor production of Nannochloropsis gaditana: an evaluation of the effects of pH on culture performance in tubular photobioreactors

Autor: Luiza Moraes, I. M. Cara, Gabriel Martins da Rosa, Jorge Alberto Vieira Costa, E. Molina Grima, Michele Greque de Morais, F.G. Acién Fernández, Lucielen Oliveira Santos
Rok vydání: 2020
Předmět:
Zdroj: Bioprocess and Biosystems Engineering. 43:1823-1832
ISSN: 1615-7605
1615-7591
Popis: A priority of the industrial applications of microalgae is the reduction of production costs while maximizing algae biomass productivity. The purpose of this study was to carry out a comprehensive evaluation of the effects of pH control on the production of Nannochloropsis gaditana in tubular photobioreactors under external conditions while considering the environmental, biological, and operational parameters of the process. Experiments were carried out in 3.0 m3 tubular photobioreactors under outdoor conditions. The pH values evaluated were 6.0, 7.0, 8.0, 9.0, and 10.0, which were controlled by injecting pure CO2 on-demand. The results have shown that the ideal pH for microalgal growth was 8.0, with higher values of biomass productivity (Pb) (0.16 g L−1 d−1), and CO2 use efficiency ( $$E_{\text{CO}_{2}}$$ ) (74.6% w w−1); $$R_{\text{CO}_{2}}$$ /biomass value obtained at this pH (2.42 $$\text{g}_{\text{CO}_{2}}$$ gbiomass−1) was close to the theoretical value, indicating an adequate CO2 supply. At this pH, the system was more stable and required a lower number of CO2 injections than the other treatments. At pH 6.0, there was a decrease in the Pb and $$E_{\text{CO}_{2}}$$ ; cultures at pH 10.0 exhibited a lower Pb and photosynthetic efficiency as well. These results imply that controlling the pH at an optimum value allows higher CO2 conversions in biomass to be achieved and contributes to the reduction in costs of the microalgae production process.
Databáze: OpenAIRE
Externí odkaz: