The CO2 microalgae biorefinery: high value products from low value wastes using halophylic microalgae in the D-factory. Part1: tackling cell harvesting

Fuel-only algal systems are not currently economically feasible. Biorefineries which integrate biomass conversion processes and equipment to produce fuels, power and chemicals from biomass, offer a solution. The CO2 microalgae biorefinery (D-Factory) is cultivating strains of Dunaliella in highly saline non-potable waters in photobioreactors and open raceways and applying biorefinery concepts and European innovations in biomass processing technologies to develop a basket of compounds from Dunaliella biomass. Driving down costs by recovering the entire biomass of Dunaliella cells from a saline environment poses one of the many challenges because Dunaliella cells are both motile, and do not possess an external cell wall, making them highly susceptible to cell rupture. In this paper we tackle the problem of harvesting cells intact to recover and process the entire biomass of Dunaliella cells cultivated. Results show a centrifugal g force lower than 5000 g caused little cell disruption, while a g force higher than 9000 g led to ~40% loss of the intact cells and commensurate loss of the intracellular cytosolic marker, glycerol. By contrast using spiral plate technology to harvest the cells recovered >90% of the cells intact