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.

中文翻译：

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收获，培养和破裂的Nannochloropsis sp。浓缩浆液的流变特性。细胞

微藻生物质的生物精炼需要处理高固含量（> 10％）的浆料。迄今为止，关于使微藻细胞弱化和破裂的过程如何影响这些材料的流变特性的知识鲜为人知。为了填补文献中的空白，海洋微藻Nannochloropsis sp。浓缩浆液的流变特性。根据加工和固体浓度（12％，20％和24％w / w）进行了研究。发现新鲜收获，孵育（自动）和高压均质（HPH）浆液的剪切稀化程度高达约200 s− 1的剪切速率。更高的浓度。浆液粘度与细胞体积分数的关系无法拟合到Krieger-Dougherty模型中，这是由于细胞外聚合物质（EPS）和在孵育和细胞破裂过程中释放的细胞内细胞组分产生的网络结构所致。当包含整个细胞（即收获和培养的浆液）时，接近密堆积极限的24％浆液比浓度较低的浆液的粘性要高得多。HPH引起的细胞破裂完全改变了浆液的特性，甚至增加了浓度较低的浆液的粘度，并产生了不可逆的剪切稀化行为。在这项研究中观察到的粘度增加的幅度和不可逆的剪切稀化行为，