Nannochloris eucaryotum growth: Kinetic analysis and use of 100% CO₂

Abstract

Microalgae are receiving an increasing attention because of their potential use as CO 2 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 Nannochloris eucaryotum (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 10-3 h-1. Half saturation concentrations for nitrates (K N) and phosphates uptake (K P) were evaluated as 5.4 10-4 g N L-1 and 2.5 10-5 g P L-1 , respectively. Yield factors for nitrogen (Y N) and phosphorus (Y P) resulted to be 5.9 10-2 g N g-1 biomass and 6.0 10-3 g P g-1 biomass , respectively. The possibility of using 100% (v/v) CO 2 gas as carbon source is also evaluated for the first time in the literature as far as N. eucaryotum is concerned. The strain showed a good adaptability to high concentrations of dissolved CO 2 as well as to low pH. The lipid content under 100% CO 2 is about 16.16 %wt wt-1 and the fatty acid methyl esters composition of the extracted oil is in compliance with the European regulation for quality biodiesel.

Microalgae cultivation and metabolites production: a comprehensive review

“…Horizontal tubular PBR (Fig. c) are set up in paralel and/or in series, which offers a better incident light angle resulting in better ligth harvesting . Reflection panels can increase the light intensity and tube diameters are generally ca .…”

“…e) use impellers to provide constant agitation, while CO 2 is bubbled from the bottom. Fluorescent or LED bulbs or optical fibers can be incorporated inside these PBR . The remaining CO 2 and the O 2 generated are separated from the gas phase by a large disengagement zone.…”

Engineering Aspects Related to the Use of Microalgae for Biofuel Production and CO2 Capture from Flue Gases

“…Such behavior depends upon the fact that, under starvation conditions, nitrogen concentration is not enough for activating the metabolic pathways leading to protein synthesis required by growth so that the excess of carbon coming from photosynthesis is channeled into storage molecules such as triacylglycerides or starch (Scott et al 2010). This inverse relationship between biomass productivity and lipid content makes the choice of the suitable nitrogen concentration not straightforward since a trade-off value should be assured in order to maximize lipid productivity (Concas et al 2013(Concas et al , 2014. When considering phosphorus, microalgae are capable of metabolizing it mainly in polyphosphate form.…”

“…Therefore, in view of industrial scaling-up, the effect of nutrients concentration in the medium on biomass composition and productivity should be quantitatively evaluated (Concas et al 2013). Since nutrients concentration and supplies are among the most controllable factors in microalgae cultivation, at least the main macronutrients uptake rates need to be quantitatively evaluated for the microalgae strains candidate to industrial exploitation.…”

Prospecting the First Culture Collection of Algae of the Pernambuco Semiarid, Brazil

“…Additionally, microalgae biotechnology has been developed to produce products with various commercial applications (food, nutraceuticals, medicines, biofuels, etc.) (Concas et al, 2013;Shuba & Kifle, 2018). However, for the aforementioned applications, these microalgae must be isolated, preferably from unpolluted waters, in order to avoid genetically adapted lineages (Pfleeger et al, 1991;Nascimento et al, 2002;Saranya et al, 2015).…”