Nannochloris eucaryotum growth:
Kinetic analysis and use of 100% CO2
Alessandro Concas,Giovanni Antonio Lutzu,Antonio Mario Locci,Giacomo Cao
Abstract
Microalgae are receiving an increasing attention because of their potential use as CO<sup>2</sup> capture method and/or as feedstock for biofuels production. On the other hand the current microalgae-based technology is still not widespread since it is characterized by technical and economic constraints that hinder its full scale-up. In such contest the growth kinetics of <i>Nannochloris eucaryotum</i> (a relatively unknown marine strain) in batch and semi-batch photobioreactors is quantitatively investigated with the aim of obtaining the corresponding kinetic parameters suitable for process engineering and its optimization. In particular the maximum growth rate was evaluated to be 1.99 10<sup>-3</sup> h<sup>-1</sup>. Half saturation concentrations for nitrates (K<sub>N</sub>) and phosphates uptake (K<sub>P</sub>) were evaluated as 5.4 10<sup>-4</sup> g<sub>N</sub> L<sup>-1</sup> and 2.5 10<sup>-5</sup> g<sub>P</sub> L<sup>-1</sup>, respectively. Yield factors for nitrogen (Y<sub>N</sub>) and phosphorus (Y<sub>P</sub>) resulted to be 5.9 10<sup>-2</sup> g<sub>N g</sub><sup>-1</sup><sub>biomass</sub> and 6.0 10<sup>-3</sup> g<sub>P</sub> g<sup>-1</sup><sub>biomass</sub>, respectively. The possibility of using 100% (v/v) CO<sub>2</sub> gas as carbon source is also evaluated for the first time in the literature as far as <i>N. eucaryotum</i> is concerned. The strain showed a good adaptability to high concentrations of dissolved CO<sub>2</sub> as well as to low pH. The lipid content under 100% CO<sub>2</sub> is about 16.16 %wt wt<sup>-1</sup> and the fatty acid methyl esters composition of the extracted oil is in compliance with the European regulation for quality biodiesel.
Alessandro Concas and Giacomo Cao — Centro di Ricerca Sviluppo e Studi Superiori in Sardegna (CRS4), Loc. Piscina Manna, Edificio 1, 09010 Pula (CA), Italy
Giovanni Antonio Lutzu and Giacomo Cao — Centro Interdipartimentale di Ingegneria e Scienze Ambientali (CINSA), Universita di Cagliari e Laboratorio, di Cagliari del Consorzio \"La Chimica per l\'Ambiente\", via San Giorgio 12, 09124 Cagliari, Italy
Antonio Mario Locci and Giacomo Cao — Dipartimento di Ingegneria Meccanica, Chimica e Materiali, Universita di Cagliari, Piazza d\'Armi, 09123 Cagliari, Italy
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