title: A biorefinery from Nannochloropsis sp. microalga--extraction of oils and pigments. Production of biohydrogen from the leftover biomass.
abstract: The microalga Nannochloropsis sp. was used in this study, in a biorefinery context, as biomass feedstock for the production of fatty acids for biodiesel, biohydrogen and high added-value compounds. The microalgal biomass, which has a high lipid and pigment content (mainly carotenoids), was submitted to supercritical CO2 extraction. The temperature, pressure and solvent flow-rate were evaluated to check their effect on the extraction yield. The best operational conditions to extract 33 g lipids/100 g dry biomass were found to be at 40 °C, 300 bar and a CO2 flow-rate of 0.62 g/min. The effect of adding a co-solvent (ethanol) was also studied. When supercritical CO2 doped with 20% (w/w) ethanol was used, it was possible to extract 45 g lipids/100 g dry biomass of lipids and recover 70% of the pigments. Furthermore, the remaining biomass after extraction was effectively used as feedstock to produce biohydrogen through dark fermentation by Enterobacter aerogenes resulting in a hydrogen production yield of 60.6 mL/g dry biomass.
authors.affiliation: Laboratório Nacional de Energia e Geologia (LNEG), Unidade de Bioenergia, Estrada do Paço do Lumiar, 1649-038 Lisboa, Portugal.
authors.forename: B P
authors.initials: BP
authors.lastname: Nobre
authors.forename: F
authors.initials: F
authors.lastname: Villalobos
authors.forename: B E
authors.initials: BE
authors.lastname: Barragán
authors.forename: A C
authors.initials: AC
authors.lastname: Oliveira
authors.forename: A P
authors.initials: AP
authors.lastname: Batista
authors.forename: P A S S
authors.initials: PA
authors.lastname: Marques
authors.forename: R L
authors.initials: RL
authors.lastname: Mendes
authors.forename: H
authors.initials: H
authors.lastname: Sovová
authors.forename: A F
authors.initials: AF
authors.lastname: Palavra
authors.forename: L
authors.initials: L
authors.lastname: Gouveia
mesh_terms: D056804:Biofuels / Q000382:microbiology*; D018533:Biomass; D001709:Biotechnology / Q000379:methods*; D002851:Chromatography, High Pressure Liquid; D025924:Chromatography, Supercritical Fluid; D005285:Fermentation; D006859:Hydrogen / Q000378:metabolism*; D008055:Lipids / Q000032:analysis; D058086:Microalgae / Q000378:metabolism*; D009821:Oils / Q000302:isolation & purification*; D010860:Pigments, Biological / Q000302:isolation & purification*; D012997:Solvents / Q000737:chemistry
chemical_list: D056804:Biofuels; D008055:Lipids; D009821:Oils; D010860:Pigments, Biological; D012997:Solvents; D006859:Hydrogen