Unit operations applied for microalgae-based solid–liquid separation

Microalgae harvesting using flocculation and dissolved air flotation: Selecting the right vessel for lab-scale experiments

“…The standing crop biomass concentration in microalgal cultures is relatively low (1 -5 g•L -1 ) due to self-shading of the microalgal cells, therefore large volumes of water need to be processed at an acceptable cost to harvest microalgae. To conserve energy, this is best done in a twostage process in which the bulk of the water is removed during a pre-concentration step that generates a sludge with dry matter content of ~50 g•L -1 and a second step in which all extracellular water is removed using centrifugation to generate a biomass paste with a dry matter content of 20 % [6]. Flocculation is an interesting approach to be used during the preconcentration step as it generates large aggregates of cells that can then be easily separated from the liquid using simple gravity settling (sedimentation) [5,7].…”