Flocculation of yeast suspensions by a cationic flocculant

Suspensions of yeasts which are negatively charged have been flocculated using a cationic polyelectrolyte. The initial rate of flocculation and growth of the floc particles were dependent on the flocculant dosage and flocculation time. During flocculation, the cationic polyelectrolyte chains can adsorb via electrostatic interactions onto the yeast particle surface. The flocculant can also form bridges between yeast particles. Flocculation characteristics were measured by zeta potential, dynamic mobility, conductivity and pH measurements with two different flocculant dosages as a function of time. The zeta potential of the particles was negative during the flocculation process and its magnitude decreased with higher flocculant dosage. Micrograph images of the flocculation process indicate an increasing floc size with time.