In this study, the effect of thermo‐alkaline pretreatment and recycling of the liquid fraction (black liquor) for successive pretreatment steps on chemical composition and methane yields from horse manure was investigated. At first, horse manure was subjected to alkaline pretreatment at 70 °C for 1 h (8.6 g NaOH/100 g total solids). Pretreated biomass was then separated into solid and liquid fractions (black liquor). In the subsequent stages, black liquor was mixed with 20% (v/v) of fresh NaOH and was reused to pretreat subsequent batches of horse manure (cycles 1–4). Chemical analyses showed that thermo‐alkaline pretreatment was effective in the delignification and solubilization of organic matter and thereby increased the holocellulose (cellulose and hemicelluloses) content in the solid fraction of horse manure. On comparison with untreated horse manure methane yields (225 ± 1 L CH₄ kg⁻¹ VS_added), thermo‐alkaline pretreatment improved the methane yields of horse manure by 39% (313 ± 16 L CH₄ kg⁻¹ VS_added). However, the effectiveness of black liquor recycling on methane production decreased (from 39 to 12%) with an increase in the number of recycling steps (from 1 to 4). Nevertheless, recycling of black liquor reduced the consumption of NaOH (40%) and water use (60%). Thus, thermo‐alkaline pretreatment with liquor recycling was found to be an effective pretreatment with an economic gain of 2.4 to 10.4 compared to pretreatment without recycling. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd

中文翻译：

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在木质纤维素生物质的厌氧消化过程中通过重复使用黑液减少热碱预处理的环境足迹

在这项研究中，研究了热碱预处理和液体馏分（黑液）的循环利用对后续预处理步骤的影响，这些化学成分和马粪中甲烷的产量。首先，将马粪在70°C下进行碱预处理1 h（8.6 g NaOH / 100 g总固体）。然后将预处理的生物质分离为固体和液体部分（黑液）。在随后的阶段中，将黑液与20％（v / v）的新鲜NaOH混合，然后再用于预处理后续批次的马粪（周期1-4）。化学分析表明，热碱预处理对有机物的脱木质素和增溶有效，因此增加了马粪肥固体部分中的全纤维素（纤维素和半纤维素）含量。₄ kg的^-1 VS_添加），热碱预处理39％（313±16升CH改善马粪的甲烷产率₄ kg的^-1 VS_添加）。但是，黑液循环利用对甲烷生产的有效性随着循环步骤数量的增加（从1到4）而降低（从39％降至12％）。尽管如此，黑液的回收减少了NaOH的消耗（40％）和水的使用（60％）。因此，与不进行再循环的预处理相比，经热循环的白酒预处理是一种有效的预处理方法，经济收益为2.4至10.4。©2021化学工业协会和John Wiley＆Sons，Ltd