Ethanol biorefineries need to lower their overall production costs to become economically feasible. Two strategies to achieve this are to reduce costs using cheaper feedstocks or to increase the ethanol production yield. Low-cost feedstocks usually have high non-structural components (NSC) content; therefore, a new process is necessary to accommodate these feedstocks and overcome the negative effects of NSC. This study developed a novel ethanol biorefinery process including a biomass preprocessing step that enabled the use of lower-cost feedstocks while improving ethanol production without detoxification (overliming). Two types of poplar feedstocks were used, low-quality whole-tree chips (WTC) and high-quality clean pulp chips (CPC), to determine if the proposed process is effective while using feedstocks with different NSC contents. Technical assessment showed that acidic preprocessing increased the monomeric sugar recovery of WTC from 73.2% (untreated) to 87.5% due to reduced buffering capacity of poplar, improved sugar solubilization during pretreatment, and better enzymatic hydrolysis conversion. Preprocessing alone significantly improved the fermentability of the liquid fraction from 1–2% to 49–56% for both feedstocks while overliming improved it to 45%. Consequently, it was proposed that preprocessing can substitute for the detoxification step. The economic assessment revealed that using poplar WTC via the new process increased annual ethanol production of 10.5 million liters when compared to using CPC via overliming (base case scenario). Also, savings in total operating costs were about $10 million per year when using cheaper poplar WTC instead of CPC, and using recycled water for preprocessing lowered its total operating costs by 45-fold. The novel process developed in this study was successful in increasing ethanol production while decreasing overall costs, thus facilitating the feasibility of lignocellulosic ethanol biorefineries. Key factors to achieving this outcome included substituting overliming by preprocessing, enabling the use of lower-quality feedstock, increasing monomeric sugar recovery and ethanol fermentation yield, and using recycled water for preprocessing. In addition, preprocessing enabled the implementation of an evaporator-combustor downstream design, resulting in a low-loading waste stream that can be treated in a wastewater treatment plant with a simple configuration.

中文翻译：

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利用生物质预处理进行新型乙醇生产，以提高乙醇产量并降低总体成本

乙醇生物精炼厂需要降低其总体生产成本，以使其在经济上可行。实现此目的的两种策略是使用便宜的原料降低成本或提高乙醇的产量。低成本原料通常具有较高的非结构成分（NSC）含量；因此，有必要采用新工艺来容纳这些原料并克服NSC的负面影响。这项研究开发了一种新颖的乙醇生物精制工艺，其中包括生物质预处理步骤，该步骤能够使用低成本原料，同时提高乙醇产量而无须进行排毒（过度石灰化）。使用两种类型的杨树原料，即低质量的整棵木片（WTC）和高品质的清洁纸浆片（CPC），以确定所建议的方法在使用具有不同NSC含量的原料时是否有效。技术评估表明，由于杨树的缓冲能力降低，预处理过程中糖的溶解性提高以及更好的酶促水解转化，酸性预处理将WTC的单体糖回收率从73.2％（未处理）提高到87.5％。单独进行预处理就可以显着地将两种原料的液体馏分的可发酵性从1-2％提高到49-56％，而过度石灰化则将其提高到45％。因此，提出了预处理可以代替排毒步骤。经济评估表明，与通过超标使用CPC相比，通过新工艺使用杨树WTC可以使乙醇年产量增加1,050万升（基础案例）。另外，使用便宜的杨树WTC代替CPC每年可节省约1000万美元的总运营成本，使用再生水进行预处理将其总运营成本降低了45倍。在这项研究中开发的新方法成功地增加了乙醇的产量，同时降低了总成本，从而促进了木质纤维素乙醇生物提炼的可行性。达到此结果的关键因素包括通过预处理替代过度石灰，允许使用质量较低的原料，提高单体糖的回收率和乙醇发酵产量，以及使用循环水进行预处理。此外，预处理可实现蒸发器-燃烧器的下游设计，从而产生低负荷的废物流，可以在废水处理厂中以简单的配置对其进行处理。在这项研究中开发的新方法成功地增加了乙醇的产量，同时降低了总成本，从而促进了木质纤维素乙醇生物提炼的可行性。达到此结果的关键因素包括通过预处理替代过度石灰，允许使用质量较低的原料，提高单体糖的回收率和乙醇发酵产量，以及使用循环水进行预处理。此外，预处理可实现蒸发器-燃烧器的下游设计，从而产生低负荷的废物流，可以在废水处理厂中以简单的配置对其进行处理。在这项研究中开发的新方法成功地增加了乙醇的产量，同时降低了总成本，从而促进了木质纤维素乙醇生物提炼的可行性。达到此结果的关键因素包括通过预处理替代过度石灰，允许使用质量较低的原料，提高单体糖的回收率和乙醇发酵产量，以及使用循环水进行预处理。此外，预处理可实现蒸发器-燃烧器的下游设计，从而产生低负荷的废物流，可以在废水处理厂中以简单的配置对其进行处理。达到此结果的关键因素包括通过预处理替代过度石灰，允许使用质量较低的原料，提高单体糖的回收率和乙醇发酵产量，以及使用循环水进行预处理。此外，预处理可实现蒸发器-燃烧器的下游设计，从而产生低负荷的废物流，可以在废水处理厂中以简单的配置对其进行处理。达到此结果的关键因素包括通过预处理替代过度石灰，允许使用质量较低的原料，提高单体糖的回收率和乙醇发酵产量，以及使用循环水进行预处理。此外，预处理可实现蒸发器-燃烧器的下游设计，从而产生低负荷的废物流，可以在废水处理厂中以简单的配置对其进行处理。