Development of an integrated process of membrane filtration for harvesting carotenoid-rich Dunaliella salina at laboratory and pilot scales

Dunaliella salina is an unicellular microalga, well-known for the production of carotenoids, especially β-carotene. This microalga is very fragile and shear sensitive due to the absence of a rigid cell wall and may easily rupture when shear stress conditions are applied. This work proposes to study the pre-concentration of carotenoid-rich (“orange”) Dunaliella salina culture by membrane filtration, preceding a final concentration using low-shear centrifugation. The goal is to minimise the total capital and energy costs, ensuring a low cell integrity loss and high permeate fluxes. The harvesting process was performed under controlled permeate flux conditions at laboratory and pilot scales. At pilot scale, the harvesting of Dunaliella salina attained a final concentration factor of 10, at a permeate volumetric flux of 21 L/(m² h). When applying the two-step approach of membrane + centrifugation, the reduction of Total Cost of Ownership (TCO) and energy consumption were 70 and 76%, respectively, compared to harvesting with a one-step centrifugation approach.