Nannochloropsis gaditana grown outdoors in annular photobioreactors: Operation strategies

Abstract

Microalgae are a topic of intense research due to their potential applications in bio-based economy. However, sustainable commercial production is still overpriced due to high cultivation costs, harvesting and dewatering processes. In the present study, trials were conducted with the aim to improve daily operation strategies related to microalgae harvesting processes that did not compromise biomass productivity or the biochemical composition of the cultivated microalgae. Two experimental trials were performed in outdoor tubular annular photobioreactors to evaluate the effects of harvesting and medium dilution time (sunrise vs sunset) on Nannochloropsis gaditana biomass productivity, lipid and fatty acid content. Results showed that harvesting time had no significant effect on cell concentration and biomass productivity. Harvesting and medium dilution time did not affect lipid content. However, lipid content in samples collected at sunset was significantly higher than in samples collected at sunrise for both experimental treatments. The fatty acids profiles were mainly composed by polyunsaturated fatty acids, followed by mono-unsaturated fatty acids and saturated fatty acids. Regardless of medium dilution time, harvesting at sunset indicated that lipidic production (higher polyunsaturated fatty acids and lower saturated fatty acids) was favored without affecting the biomass productivity. The current study showed harvesting in the afternoon is a viable option for large production units that use semi-continuous strategy, without compromising biomass cell and lipid productivity.

Operation Regimes: A Comparison Based on Nannochloropsis oceanica Biomass and Lipid Productivity

“…in continuous and batch regimes using 2 L glass bubble column PBRs at the laboratory scale [36]. Regarding the lipid productivity, the values in the present study (22.9-39.6 mg L −1 day −1 ) were higher than the ones obtained by Nogueira et al (2020) for N. gaditana grown in an outdoor 100 L vertical column PBR operated in the semi-continuous regime with a dilution rate of 0.5 day −1 in winter at Porto Santo, Portugal (7.2-17.82 mg L −1 day −1 ) [37]. The difference can be attributed to the temperature and irradiance differences between seasons since the literature shows a positive correlation between temperature and lipid content in Nannochloropsis sp.…”

Polystyrene microplastics exposure modulated the content and the profile of fatty acids in the Cladoceran Daphnia magna

“…The fatty acids (FAs) composition of dried D. magna individuals was determined and expressed as FA methyl esters (FAMEs), as described by Nogueira et al (2020). Briefly, FAs were converted to FAMEs by adding a mixture of ethyl acetate-methanol (1:19 v/v) to dry biomass that was then left at 80 ºC for 1 h and then further extracted with heptane.…”

Innovative and Healthier Dairy Products through the Addition of Microalgae: A Review

“… Information adapted from: 1 Ran et al [ 12 ]; Mehariya et al [ 13 ]; Rodrigues-Sousa et al [ 14 ]; 2 Ran et al [ 15 ]; Fattore et al [ 16 ]; Nogueira et al [ 17 ]; 3 Shanthi et al [ 18 ]; Batista de Oliveira et al [ 19 ]; Morais et al [ 20 ]; 4 Xing et al [ 21 ]; Polat et al [ 22 ]; Bohutskyi et al [ 23 ]; 5 Jung et al [ 24 ]; Zhu et al [ 25 ]; Kottuparambil et al [ 26 ]; 6 Kumudha and Sarada [ 27 ]; Mixson Byrd and Burkholder [ 28 ]; Torres-Tiji et al [ 7 ]; 7 Pereira et al [ 29 ]; Schulze et al [ 30 ]; Qazi et al [ 31 ]. n.r—not reported.…”