This work is focused on production of volatile fatty acids (VFA) through anaerobic digestion (AD) using raw (without pre-treatment) brewers' spent grain (BSG) as feedstock. VFAs are by-products from AD of organic wastes with wide potential industrial application in bioplastic production. A long term fed batch stirred-tank reactor was operated and the impact of three hydraulic retention times (HRT) and two organic loading rates (OLR) on VFA production was assessed. Results showed clearly that AD of raw BSG is possible without a pre-treatment step. The maximum volumetric VFA productivity of 91.3 ± 9.1 mgCODL-1 h-1 and VFA concentration of 24.9 ± 2.6 g L-1 were obtained for 16 days of HRT and 16 gTSinL-1d-1 of OLR. This is the highest value of VFA concentration so far reported for BSG. Propionic, acetic and butyric acids were the main VFAs produced. Community identification by FISH and its correlation with process parameters was performed by principal component analysis.

中文翻译：

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通过生产挥发性脂肪酸使生啤酒废谷物增值

这项工作的重点是通过厌氧消化 (AD) 生产挥发性脂肪酸 (VFA)，使用原始（未经预处理）啤酒糟 (BSG) 作为原料。VFA 是有机废物 AD 的副产品，在生物塑料生产中具有广泛的潜在工业应用。运行长期补料分批搅拌釜反应器，并评估了三个水力停留时间 (HRT) 和两个有机负载率 (OLR) 对 VFA 生产的影响。结果清楚地表明，无需预处理步骤即可对原始 BSG 进行 AD。对于 16 天的 HRT 和 16 gTSinL-1d-1 的 OLR，获得了 91.3 ± 9.1 mgCODL-1 h-1 的最大体积 VFA 生产率和 24.9 ± 2.6 g L-1 的 VFA 浓度。这是迄今为止为 BSG 报告的 VFA 浓度的最高值。丙酸，乙酸和丁酸是产生的主要 VFA。FISH 的群落识别及其与工艺参数的相关性通过主成分分析进行。