Floc size dynamics in flotation based separation for marine microalgae biomass production
Vandamme, Dries × Wong, Yu W. Vronska, Oksana Tamburic, Bojan Henderson, Rita #
The 7th International Conference on Flotation for Water and Wastewater systems pages:161-167
International IWA conference on flotation for water and wastewater systems edition:7 location:Toulouse date:26-30 September 2016
The production of marine microalgae for biomass production is facing several challenges to become competitive source of renewable energy. A major challenge is harvesting, which requires solid-liquid separation of a low amount of biomass consisting of small individual cells from a large volume of marine culture medium. Flotation is a promising low-cost method which has been established for the separation of freshwater microalgae in water treatment. The aim of this study was to compare flotation versus sedimentation and to evaluate and optimize dissolved air flotation using ferric chloride versus alkaline coagulation for Nannochloropsis oculata. Separation efficiency has been compared as a function of the required coagulant dose of optimal separation and the resultant concentration factor. Ferric chloride as coagulant resulted both in a better separation and concentration of the biomass as function of coagulant dose compared to alkaline coagulation. However, this coagulant will lead to accumulation of iron in the biomass prior to further processing. Floc formation and breakage have been studied by measuring floc size distributions. It was shown that alkaline flocs were significantly smaller than ferric chloride flocs at the end of the flocculation step. However, the size of alkaline flocs remained very stable under the applied floc breakage conditions.