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Size and structure of Chlorella zofingiensis /FeCl 3 flocs in a shear flow
Author(s) -
Wyatt Nicholas B.,
O'Hern Timothy J.,
Shelden Bion,
Hughes Lindsey G.,
Mondy Lisa A.
Publication year - 2013
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.24996
Subject(s) - flocculation , settling , shear rate , algae , shear (geology) , rheology , chlorella , materials science , chemical engineering , environmental science , environmental engineering , botany , composite material , biology , engineering
Flocculation is a promising method to overcome the economic hurdle to separation of algae from its growth medium in large scale operations. However, understanding of the floc structure and the effects of shear on the floc structure are crucial to the large scale implementation of this technique. The floc structure is important because it determines, in large part, the density and settling behavior of the algae. Freshwater algae floc size distributions and fractal dimensions are presented as a function of applied shear rate in a Couette cell using ferric chloride as a flocculant. Comparisons are made with measurements made for a polystyrene microparticle model system taken here as well as reported literature results. The algae floc size distributions are found to be self‐preserving with respect to shear rate, consistent with literature data for polystyrene. Three fractal dimensions are calculated which quantitatively characterize the complexity of the floc structure. Low shear rates result in large, relatively dense packed flocs which elongate and fracture as the shear rate is increased. The results presented here provide crucial information for economically implementing flocculation as a large scale algae harvesting strategy. Biotechnol. Bioeng. 2013;110: 3156–3163. © 2013 Wiley Periodicals, Inc.