Lago Adrián, Greses Silvia, Moreno Inés, González-Fernández Cristina
Biotechnology Processes Unit, IMDEA Energy, Avda. Ramón de la Sagra 3, Móstoles, Madrid, 28935, Spain.
Thermochemical Processes Unit, IMDEA Energy, Avda. Ramón de la Sagra 3, Móstoles, Madrid, 28935, Spain.
Bioresour Bioprocess. 2025 Jan 24;12(1):6. doi: 10.1186/s40643-025-00839-y.
This research investigated the acidogenic fermentation (AF) of sugar cane molasses in an up-flow anaerobic sludge blanket (UASB) reactor for the production of carboxylates. The first step was to assess the optimum process temperature (25, 35 or 55 ºC) using two different granular inocula, one from a brewery company (BGS) and other from a paper plant company (PGS). These experiments determined that the most suitable temperature for carboxylates production was 25 ºC, obtaining higher bioconversions (27.3 ± 0.3% using PGS and 39.2 ± 0.2% using BGS), despite the low pH value recorded (4.0-4.2). Then, both inocula were tested in UASB reactors. As a consequence of the operational conditions (25 ºC, pH = 5.5-6, organic loading rate (OLR) = 3 g·L·d and hydraulic retention time (HRT) = 10 d), the microbial communities changed from those typical for biogas production to those specialised in the production of volatile fatty acids (VFAs). Indeed, the highest bioconversion efficiency (70.1%) was obtained with BGS, where uncultured Eubacteriaceae family microorganisms (56.0%) prevailed, enhancing the production of butyric acid (59.5 ± 2.4%w/w). Consequently, this inoculum was used to further identify the OLR threshold that should not be exceeded to attain optimal carboxylates production. OLR of 6 g·L·d resulted in a decrease in bioconversion efficiency (59.5%). The VFAs pool was dominated by butyric acid (63.0 ± 1.4%w/w at an OLR of 4.5 g·L·d and 52.8 ± 2.2%w/w at 6 g·L·d). The microbial community became even more specialised, increasing the presence of Firmicutes and Actinobacteriota phyla, proving that the imposed conditions favoured the production of VFAs when operating semicontinuously fed UASB reactors.
本研究调查了在升流式厌氧污泥床（UASB）反应器中甘蔗废蜜的产酸发酵（AF）过程，以生产羧酸盐。第一步是使用两种不同的颗粒接种物评估最佳工艺温度（25、35或55℃），一种来自啤酒厂公司（BGS），另一种来自造纸厂公司（PGS）。这些实验确定，尽管记录的pH值较低（4.0 - 4.2），但生产羧酸盐的最合适温度为25℃，可获得更高的生物转化率（使用PGS时为27.3±0.3%，使用BGS时为39.2±0.2%）。然后，在UASB反应器中对两种接种物进行了测试。由于操作条件（25℃，pH = 5.5 - 6，有机负荷率（OLR）= 3 g·L⁻¹·d⁻¹，水力停留时间（HRT）= 10 d），微生物群落从典型的沼气生产群落转变为专门生产挥发性脂肪酸（VFA）的群落。事实上，使用BGS时获得了最高的生物转化效率（70.1%），其中未培养的真杆菌科微生物（56.0%）占优势，提高了丁酸的产量（59.5±2.4%w/w）。因此，该接种物被用于进一步确定为实现最佳羧酸盐生产不应超过的OLR阈值。6 g·L⁻¹·d⁻¹的OLR导致生物转化效率下降（59.5%）。VFA库以丁酸为主（在OLR为4.5 g·L⁻¹·d⁻¹时为63.0±1.4%w/w，在6 g·L⁻¹·d⁻¹时为52.8±2.2%w/w）。微生物群落变得更加专门化，厚壁菌门和放线菌门的存在增加，这证明在半连续进料的UASB反应器运行时，所施加的条件有利于VFA的生产。
