Exploring the synergy between membrane filtration and flocculation for harvesting microalgae
The aim of this project is to combine flocculation with membrane filtration for harvesting microalgae. Flocculation in itself is insufficient as a harvesting method and depends on a physical method to separate the microalgae from the culture medium. While sedimentation, centrifugation or flotation can be used in combination with flocculation, the removal of the biomass is rarely 100% effective. When membrane filtration is used, complete separation could be achieved. Membrane filtration of microalgal cultures after flocculation should be more effective after flocculation of the microalgae. Because flocculation increases the particle size of microalgae, we hypothesize that blocking of pores by microalgal cells will be reduced. Moreover, membranes with larger pore sizes can be used, which increases fluxes and reduces energy demand. Flocculants will reduce the surface charge of microalgal cells, which may in turn reduce the interaction of microalgal cells with membranes and thus reduce fouling. There is evidence that flocculants not only interact with microalgal cells but also with dissolved organic matter excreted by microalgae into the culture medium and this might further reduce membrane fouling.