An auto-flocculation strategy for Chlorella vulgaris

Extracellular polymeric substances (EPS) excreted by microalgae are effective for microalgal flocculation. An auto-flocculation strategy was conducted by adding adequate glycine into the medium, stimulating EPS secretion to achieve auto-flocculation, and recycling the supernatant medium for further cultivation. Bound EPS positively corresponded with the solid concentration achieved. Increasing the mixing time enhanced the secretion of bound EPS but the influence of glycine was affected by light intensity. Increasing the glycine dose decreased the production of bound EPS with light intensity of 250 μmol m(-2) s(-1), but increased the production of bound EPS with light intensity of 125 μmol m(-2) s(-1). Maximum solid concentration of 21.2 g l(-1) with biomass recovery rate of 71 % was achieved under light intensity of 250 μmol m(-2) s(-1), mixing time of 3 days and glycine at 0.1 g l(-1).