TY - JOUR
T1 - Enhanced Microalgal Harvesting Using Microalgae-Derived Extracellular Polymeric Substance as Flocculation Aid
AU - Yang, Lin
AU - Zhang, Haiyang
AU - Cheng, Shaozhe
AU - Zhang, Wen
AU - Zhang, Xuezhi
N1 - Funding Information:
The authors gratefully appreciate the financial support from National Program on Basic Research Project for Governmental International Scientific and Technological Innovation Cooperation of China (2018YFE0110600), One Hundred Scholars Award from the Chinese Academy of Sciences (Y62305-1-Z01), and National Natural Science Foundation of China (51909258).
Publisher Copyright:
Copyright © 2020 American Chemical Society.
PY - 2020/3/16
Y1 - 2020/3/16
N2 - Coagulation-based harvesting has been widely used in microalgal biomass harvesting. However, the coagulant contamination in the harvested biomass may negatively affect the applications in feedstock processing for food, feed, and fuel. In this study, extracellular polymeric substances (EPSs) were derived from microalgae, Scenedesmus acuminatus, and then used as a bioflocculant to aid the flocculation of the same algae. The results show that the alum coagulant (Al3+) usage was significantly reduced from 77.6 to 4.5 mg g-1 when adding this EPS bioflocculant at a dose of 3.2 mg g-1, which potentially reduces the chemical cost from $282 per metric ton to $71 per metric ton dry biomass that is harvested. To analyze the compositions of this bioflocculant, molecular fractionation was performed. The functional fractions such as protein-like and humic-like organic substances were characterized by fluorescence excitation-emission, followed by polysaccharide analysis. Low-MW (<3 kDa) EPS contributed to the flocculation process more than the large-MW fractions. Low-MW EPS contained higher contents of glucose and mannose in the polysaccharide that influence the interactions of the algae and the alum coagulant. Microalgal-derived bioflocculants may open up new avenue toward the low-cost and sustainable bioflocculation processes for algal and other biomass separation.
AB - Coagulation-based harvesting has been widely used in microalgal biomass harvesting. However, the coagulant contamination in the harvested biomass may negatively affect the applications in feedstock processing for food, feed, and fuel. In this study, extracellular polymeric substances (EPSs) were derived from microalgae, Scenedesmus acuminatus, and then used as a bioflocculant to aid the flocculation of the same algae. The results show that the alum coagulant (Al3+) usage was significantly reduced from 77.6 to 4.5 mg g-1 when adding this EPS bioflocculant at a dose of 3.2 mg g-1, which potentially reduces the chemical cost from $282 per metric ton to $71 per metric ton dry biomass that is harvested. To analyze the compositions of this bioflocculant, molecular fractionation was performed. The functional fractions such as protein-like and humic-like organic substances were characterized by fluorescence excitation-emission, followed by polysaccharide analysis. Low-MW (<3 kDa) EPS contributed to the flocculation process more than the large-MW fractions. Low-MW EPS contained higher contents of glucose and mannose in the polysaccharide that influence the interactions of the algae and the alum coagulant. Microalgal-derived bioflocculants may open up new avenue toward the low-cost and sustainable bioflocculation processes for algal and other biomass separation.
KW - algal harvesting
KW - bioflocculation
KW - extracellular polymeric substances
KW - polysaccharide
KW - sustainable engineering
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U2 - 10.1021/acssuschemeng.9b06156
DO - 10.1021/acssuschemeng.9b06156
M3 - Article
AN - SCOPUS:85082661815
SN - 2168-0485
VL - 8
SP - 4069
EP - 4075
JO - ACS Sustainable Chemistry and Engineering
JF - ACS Sustainable Chemistry and Engineering
IS - 10
ER -