Microalgal biomass is an emerging source of renewable energy and health-related compounds. However, harvesting of microalgae is a techno-economic hinder. In this research, chitosan and polyacrylamide were optimized harvesting condition for Chlorella vulgaris. Stirring at 300 rpm for 2 min is optimum for chitosan and polyacrylamide. Low-dose (10 mg/L) chitosan (flocculation efficiency (FE), 98.10 ± 1.06%) is more efficient than high-dose (25 mg/L) polyacrylamide (FE 94.57 ± 0.55%) for harvesting C. vulgaris. Chitosan resulted flocs settled more quickly than polyacrylamide, while polyacrylamide keep > 90% FE in a wider pH range (7-10) than chitosan (7-8). Chitosan and polyacrylamide both have no negative effect on biomass composition, including protein, carbohydrate, and carotenoid. C. vulgaris in flocs could successfully regrow in fresh culture media. The residual culture media was recycled with little impact on cell growth. All the results suggested that chitosan and polyacrylamide could harvest high-quality microalgal biomass.
Keywords: Floc; Flocculation; Microalgae; Spent medium recycle.
© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.