He Yaxue, Cassarini Chiara, Lens Piet N L
National University of Ireland Galway Galway Ireland.
Eng Life Sci. 2022 Dec 7;23(2):e2200027. doi: 10.1002/elsc.202200027. eCollection 2023 Feb.
An anaerobic granular sludge was enriched to utilize H/CO in a continuous gas-fed up-flow anaerobic sludge reactor by applying operating conditions expected to produce acetic acid, butyric acid, and ethanol. Three stages of fermentation were found: Stage I with acetic acid accumulation with the highest concentration of 35 mM along with a pH decrease from initial 6 to 4.5. In Stage II, H/CO was replaced by 100% H to induce solventogenesis, whereas butyric acid was produced with the highest concentration of 2.5 mM. At stage III with 10 µM tungsten (W) addition, iso-valeric acid, valeric acid, and caproic acid were produced at pH 4.5-5.0. In the batch tests inoculated with the enriched sludge taken from the bioreactor (day 70), however, methane production occurred at pH 6. Exogenous 15 mM acetate addition enhanced both the H and CO consumption rate compared to exogenous 10, 30, and 45 mM acetate by the enriched sludge. Exogenous acetate was failed to be converted to ethanol using H as electron donor by the enriched acetogens.
通过应用预期能产生乙酸、丁酸和乙醇的运行条件，在连续供气的上流式厌氧污泥反应器中富集厌氧颗粒污泥以利用H/CO。发现了三个发酵阶段：第一阶段乙酸积累，最高浓度为35 mM，同时pH从初始的6降至4.5。在第二阶段，H/CO被100% H替代以诱导溶剂生成，同时产生最高浓度为2.5 mM的丁酸。在第三阶段添加10 µM钨（W）时，在pH 4.5 - 5.0条件下产生异戊酸、戊酸和己酸。然而，在接种取自生物反应器（第70天）的富集污泥的批次试验中，在pH 6时产生甲烷。与富集污泥利用10、30和45 mM外源乙酸相比，添加15 mM外源乙酸提高了H和CO的消耗速率。富集的产乙酸菌未能利用H作为电子供体将外源乙酸转化为乙醇。
