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High-solids saccharification and fermentation is central to the cost-competitive production of cellulosic ethanol, but it often comes with unsatisfactory conversion efficiency because of mixing and heat/mass transfer limitations. The use of ball milling can considerably enhance enzymatic hydrolysis with desirable rheological properties at high solids, and we obtained a high sugar concentration of 162 g/L with a glucose yield of 74% after enzymatic hydrolysis. However, little is known about the impact of ball milling on subsequent fermentation of sugars to ethanol as well as the feasibility of producing high titer bioethanol from ball-milled materials at high solids loading. Here, we systematically evaluated various fermentation strategies to maximize the efficiency and economic benefits of bioethanol production using ball-milled corn stover at high solids loading. A high ethanol titer and productivity can be achieved up to 71.8 g/L and 2 g/L/h, respectively, with an ethanol yield of 58.8%. These results suggest the tremendous potential of ball milling for bioethanol production. [Display omitted] [ABSTRACT FROM AUTHOR]

• The rheological behavior of corn stover slurry at different plant scales was obtained. • Particle size and porosity are the key factors affecting rheological behavior. • Size reduction to cellular scale could significantly reduce the viscosity and yield stress. • Quantitative analysis for free water amount, particle size and rheological parameters. A fundamental understanding of the rheology of high-solids lignocellulose slurry is essential for the design of efficient cellulosic ethanol production processes and bioreactors. Here we analyzed the rheological properties of high-solids corn stover slurries with particles size ranged from tissue scale to cellular scale. Results showed that the apparent viscosity/yield stress decreased with the increase of free water amount and the decrease of particle size, and the quantitative relationships among them were obtained. A 300-fold and 130-fold decrease in apparent viscosity and yield stress (30 % solids loading) were observed when the corn stover was reduced to cellular scale (≤ 50 μm). Further analysis revealed that size reduction to tissue scale reduces the viscosity and yield stress by alleviating the interactions between particles, while size reduction to cellular scale not only weakens the particle interactions, but also increases free water amount due to destruction of cell lumen, thus greatly enhances the rheological behaviors. And this improvement is undoubtedly of great significance for inter-unit operation and mixing energy saving. [ABSTRACT FROM AUTHOR]