This study investigated three different fermentation approaches to explore the potential for producing biohydrogen, carboxylic acids, and methane from hydrolysates of thermally dilute acid pretreated brewer's spent grains (BSG). Initially, the research focused on maximizing the volumetric hydrogen production rate (HPR) in the continuous dark fermentation (DF) of BSG hydrolysates by varying the hydraulic retention time (HRT). The highest HPR reported to date of 5.9 NL/L-d was achieved at 6 h HRT, with a Clostridium-dominated microbial community. The effect of the operational pH (4, 5, 6, and 7) on the continuous acidogenic fermentation was then investigated. A peak carboxylic acid concentration of 17.3 g CODequiv./L was recorded at pH 6, with an associated volumetric productivity of 900.5 ± 13.1 mg CODequiv./L-h and a degree of acidification of 68.3 %. Lactic acid bacteria such as Limosilactobacillus and Lactobacillus were dominant at pH 4–5, while Weissella, Enterococcus, and Lachnoclostridium appeared at pH 6 and 7. Finally, this study evaluated the biochemical methane potential of the DF broth and the unfermented hydrolysates and found high methane yields of 659 and 517 NmL CH4/g-VSadded, respectively, both within one week. Overall, the results showed that pretreated BSG can be a low-cost feedstock for the production of bioenergy and valuable bio-based chemicals in a circular economy.

中文翻译：

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啤酒厂通过发酵进行麦废谷物估价：针对生物氢、羧酸和甲烷生产


本研究调查了三种不同的发酵方法，以探索从热稀酸预处理的啤酒渣 （BSG） 的水解物中生产生物氢、羧酸和甲烷的潜力。最初，研究的重点是通过改变水力停留时间 （HRT） 来最大限度地提高 BSG 水解物连续黑暗发酵 （DF） 中的体积法制氢速率 （HPR）。迄今为止报道的最高 HPR 为 5.9 NL/L-d 是在 6 小时 HRT 时达到的，具有梭状芽胞杆菌为主的微生物群落。然后研究操作 pH 值（4、5、6 和 7）对连续产酸发酵的影响。在 pH 值为 6 时，记录的羧酸峰值浓度为 17.3 g CODequiv./L，相关的体积生产率为 900.5 ± 13.1 mg CODequiv./L-h，酸化程度为 68.3 %。乳酸菌（如 Limosilactobacillus 和 Lactobacillus）在 pH 值为 4-5 时占主导地位，而魏斯氏菌属、肠球菌属和拉赫梭菌属（Lachnoclostridium） 在 pH 值为 6-7 时出现。最后，本研究评估了 DF 肉汤和未发酵水解物的生化甲烷潜力，发现一周内甲烷产量分别为 659 和 517 NmL CH4/g-VSadd。总体而言，结果表明，预处理后的 BSG 可以成为在循环经济中生产生物能源和有价值的生物基化学品的低成本原料。