title: Enhanced Harvesting of Chlorella vulgaris Using Combined Flocculants.
abstract: 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.
authors.affiliation: Institute of Microbiology, Chinese Academy of Sciences, A3 Datun Road, Chaoyang District, Beijing, 100101, People's Republic of China.|Center for Biorefining and Department of Bioproducts and Biosystems Engineering, University of Minnesota, 1390 Eckles Ave., St. Paul, MN, 55108, USA.
authors.forename: Xiaochen
authors.initials: X
authors.lastname: Ma
authors.affiliation: MOE Biomass Energy Research Center and College of Food Science and State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047, People's Republic of China.
authors.forename: Hongli
authors.initials: H
authors.lastname: Zheng
authors.affiliation: Center for Biorefining and Department of Bioproducts and Biosystems Engineering, University of Minnesota, 1390 Eckles Ave., St. Paul, MN, 55108, USA.
authors.forename: Wenguang
authors.initials: W
authors.lastname: Zhou
authors.affiliation: MOE Biomass Energy Research Center and College of Food Science and State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047, People's Republic of China.
authors.forename: Yuhuan
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Center for Biorefining and Department of Bioproducts and Biosystems Engineering, University of Minnesota, 1390 Eckles Ave., St. Paul, MN, 55108, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Chen
authors.affiliation: Center for Biorefining and Department of Bioproducts and Biosystems Engineering, University of Minnesota, 1390 Eckles Ave., St. Paul, MN, 55108, USA. ruanx001@umn.edu.|MOE Biomass Energy Research Center and College of Food Science and State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047, People's Republic of China. ruanx001@umn.edu.
authors.forename: Roger
authors.initials: R
authors.lastname: Ruan
mesh_terms: D018533:Biomass; D017610:Calcium Compounds / Q000494:pharmacology*; D002498:Centrifugation; D048408:Chlorella vulgaris / Q000166:cytology / Q000187:drug effects / Q000254:growth & development*; D005427:Flocculation / Q000187:drug effects; D007477:Ions; D058086:Microalgae / Q000166:cytology / Q000187:drug effects / Q000254:growth & development; D010087:Oxides / Q000494:pharmacology*; D011099:Polyglutamic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D059027:Recycling
chemical_list: D017610:Calcium Compounds; D007477:Ions; D010087:Oxides; C511775:poly(gamma-glutamic acid); D011099:Polyglutamic Acid; C016538:lime
keywords: Biofuels; Biomass harvest; Bioproducts; Combined flocculants; Microalga