Enhanced Harvesting of Chlorella vulgaris Using Combined Flocculants

Xiaochen Ma, Hongli Zheng, Wenguang Zhou, Yuhuan Liu, Paul Chen, Roger Ruan

Research output: Contribution to journalArticle

5 Scopus citations


In this study, a novel flocculation strategy for harvesting Chlorella vulgaris with combined flocculants, poly (γ-glutamic acid) (γ-PGA) and calcium oxide (CaO), has been developed. The effect of flocculant dosage, the order of flocculant addition, mixing speed, and growth stage on the harvesting efficiency was evaluated. Results showed that the flocculation using combined flocculants significantly decreases the flocculant dosage and settling time compared with control. It was also found that CaO and γ-PGA influenced microalgal flocculation by changing the zeta potential of cells and pH of microalgal suspension. The most suitable order of flocculant addition was CaO first and then γ-PGA. The optimal mixing speed was 200 rpm for 0.5 min, followed by 50 rpm for another 4.5 min for CaO and γ-PGA with the highest flocculation efficiency of 95 % and a concentration factor of 35.5. The biomass concentration and lipid yield of the culture reusing the flocculated medium were similar to those when a fresh medium was used. Overall, the proposed method requires low energy input, alleviates biomass and water contamination, and reduces utilization of water resources and is feasible for harvesting C. vulgaris for biofuel and other bio-based chemical production.

Original languageEnglish (US)
Pages (from-to)791-804
Number of pages14
JournalApplied Biochemistry and Biotechnology
Issue number4
StatePublished - Oct 1 2016


  • Biofuels
  • Biomass harvest
  • Bioproducts
  • Combined flocculants
  • Microalga

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