Substrate and product inhibitions have a significant effect on dark fermentative hydrogen gas production. Particularly, rapid formation of volatile fatty acids leads to fast pH decreases shifting the metabolic pathway. Therefore, controlling volatile fatty acid accumulation has great importance in maintaining effective hydrogen production. In this context, a dilution strategy was applied to regulate volatile fatty acids levels within the desired concentration range. A three-factor Box-Behnken statistical experiment design was established to assess the effects of dilution time, dilution percentage and initial COD concentration on hydrogen formation yield and rate. Highest hydrogen yield (7.7 mL H/mL) and rate (21. 47 mL H/h or 9.38 mmol/L.h) were achieved when 85 gCOD/L containing fermentation media was diluted with a percentage of 130 of the initial working volume at the 3rd hour of the fermentation period. Moreover, this strategy enabled to start fermentation with 55 g glucose/L.

中文翻译：

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在糖蜜暗发酵制氢过程中使用稀释策略来防止底物和产物抑制


底物和产物抑制对暗发酵氢气产生具有显着影响。特别是，挥发性脂肪酸的快速形成导致 pH 值快速降低，从而改变代谢途径。因此，控制挥发性脂肪酸的积累对于维持有效的产氢具有重要意义。在这种情况下，采用稀释策略将挥发性脂肪酸水平调节在所需的浓度范围内。建立了三因素Box-Behnken统计实验设计来评估稀释时间、稀释百分比和初始COD浓度对氢气形成产率和速率的影响。当含有 85 gCOD/L 的发酵培养基在初始工作体积的 130 倍稀释时，获得最高的氢气产量 (7.7 mL H/mL) 和速率 (21. 47 mL H/h 或 9.38 mmol/L.h)。发酵第3小时。此外，该策略能够以 55 g 葡萄糖/L 开始发酵。