Rheological properties of concentrated slurries of harvested, incubated and ruptured Nannochloropsis sp. cells

BMC Chemical Engineering

Gregory J. O. Martin¹  Peter J. Scales¹  Sam Q. K. Law¹  Zheng Sun²  Muthupandian Ashokkumar³  Shunyu Yao³  Srinivas Mettu⁴ 

[1] Algal Processing Group, Department of Chemical Engineering, The University of Melbourne, 3010, Parkville, Victoria, Australia;International Research Center for Marine Biosciences, Ministry of Science and Technology, Shanghai Ocean University, 201306, Shanghai, China;Sonochemistry Group, School of Chemistry, The University of Melbourne, Parkville, 3010, Melbourne, Victoria, Australia;Sonochemistry Group, School of Chemistry, The University of Melbourne, Parkville, 3010, Melbourne, Victoria, Australia;Algal Processing Group, Department of Chemical Engineering, The University of Melbourne, 3010, Parkville, Victoria, Australia;

关键词: Algae Biofuels;    Incubation;    Cell Rupture;    Shear Rheology;    Suspension Viscosity;    Viscoelastic behaviour;   

DOI  :  10.1186/s42480-019-0011-y

来源: Springer

【 摘 要 】

Biorefining of microalgae biomass requires processing of high-solids (> 10%) slurries. To date there is little knowledge of how processes for weakening and rupturing microalgae cells affect the rheological properties of these materials. To fill this gap in the literature, the rheological properties of concentrated slurries of marine microalgae Nannochloropsis sp. were investigated as a function of processing and solids concentration (12, 20 and 24% w/w). Freshly harvested, incubated (autolysed), and high-pressure homogenised (HPH) slurries were found to be shear thinning up to a shear rate of approximately 200 s− 1. Viscosity increases were far more prominent for partially processed versus unprocessed algal pastes at the higher concentrations. Slurry viscosity as a function of cell volume fraction could not be fitted to the Krieger-Dougherty model due to a network structure resulting from extracellular polymeric substances (EPS) and the intracellular cell components released during incubation and cell rupture. The 24% slurry, which was near the close packing limit, was much more viscous than the less concentrated slurries when comprising whole cells (i.e. harvested and incubated slurries). Cell rupture by HPH completely altered the characteristics of the slurry, increasing the viscosity of even the less concentrated slurries, and producing irreversible shear thinning behaviour. The magnitude of the increases in viscosities and the irreversible shear thinning behaviour observed in this study, have significant implications for processing and optimising the solids concentration of algal slurries.

【 授权许可】

CC BY