Background High-solids enzymatic hydrolysis has attracted increasing attentions for the production of bioethanol from lignocellulosic biomass with its advantages of high product concentration, water saving, and low energy and capital costs. However, the increase of solids content would worsen the rheological properties, resulting in heat/mass transfer limitation and higher mixing energy. To address these issues, ball milling was applied to corn stover prior to enzymatic hydrolysis, and the rheological behaviors and digestibility of ball-milled corn stover under high-solids loading were investigated. Results Ball milling significantly modified the physicochemical properties of corn stover. The apparent viscosity of slurries at 30% solid loading decreased by a factor of 500 after milling for 60 min, and the yield stress was less than 10 Pa. The dramatic decrease of viscosity and yield stress enabled the hydrolysis process to be conducted in shake flask, and remained good mixing. Meanwhile, the estimated energy consumption for mixing during saccharification decreased by 400-fold compared to the untreated one. The resultant hydrolysate using 10 FPU g-1 solids was determined to contain 130.5 g L-1 fermentable sugar, and no fermentation inhibitors were detected. Conclusions The proposed ball milling pretreatment improved rheological behavior and sugar yield of high-solids corn stover slurry. Ball milling enables high-solids slurry to maintain low viscosity and yield stress while obtaining a non-toxic high-concentration fermentable syrup, which is undoubtedly of great significance for inter-unit processing, mixing and downstream process. In addition, the energy input for ball milling could be balanced by the reduced mixing energy. Our study indicates ball milling a promising pretreatment process for industrial bioethanol production.

中文翻译：

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球磨玉米秸秆的高固含量酶水解降低了浆料粘度并提高了糖产量。

背景高固含量酶解法以其产品浓度高、节水、能源和资金成本低等优点，越来越受到人们对木质纤维素生物质生物乙醇的关注。然而，固体含量的增加会恶化流变性能，导致传热/传质受限和更高的混合能。为了解决这些问题，在酶水解之前将球磨应用于玉米秸秆，并研究了球磨玉米秸秆在高固体负荷下的流变行为和消化率。结果球磨显着改变了玉米秸秆的理化性质。30%固含量的浆料在研磨60 min后表观粘度降低了500倍，屈服应力小于10 Pa。粘度和屈服应力的急剧下降使水解过程能够在摇瓶中进行，并保持良好的混合。同时，与未处理的相比，糖化期间混合的估计能量消耗减少了 400 倍。使用 10 FPU g-1 固体得到的水解产物经测定含有 130.5 g L-1 可发酵糖，并且未检测到发酵抑制剂。结论 所提出的球磨预处理改善了高固含量玉米秸秆浆的流变行为和糖产量。球磨使高固含量浆料在保持低粘度和屈服应力的同时获得无毒的高浓度可发酵糖浆，这对于单元间加工、混合和下游工艺无疑具有重要意义。此外，球磨的能量输入可以通过降低的混合能量来平衡。我们的研究表明，球磨是一种很有前景的工业生物乙醇生产预处理工艺。