We previously observed that as glucose is completely exhausted during ethanol fermentation, the dissolved carbon dioxide (DCO₂) level in the fermenter will suddenly decline. This observation was implemented to design and develop a DCO₂‐driven‐and‐controlled repeated batch fermentation process for ethanol production. The process was tested at four different glucose concentrations (~150 g/L, ~200 g/L, ~250 g/L, and ~300 g/L), and each glucose concentration was controlled under three respective DCO₂ control levels (without DCO₂ control, and DCO₂ controlled at either 1000 mg/L or 750 mg/L). The results show that reported process features complete glucose utilization and is self‐driven. For glucose concentration less than 200 g/L, ~41%‐50% of fermentation time per batch was saved during the repeated batch operation. It took 12.1 ± 1.1 hours‐14.9 ± 1.9 hours to complete a batch with glucose feed at ~250 g/L and 21.7 ± 6 hours‐31.5 ± 7 hours to complete a batch with glucose feed at ~300 g/L. The reported process is time saving and stable, but the ethanol yield is ~20% lower than the operation without DCO₂ control. Dissolved CO₂ control became essential for glucose concentrations greater than 250 g/L if zero glucose discharge in each batch during the operation is desired.

中文翻译：

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开发溶解二氧化碳驱动和控制的重复分批发酵工艺以生产乙醇

我们先前观察到，由于乙醇发酵过程中葡萄糖已完全耗尽，因此发酵罐中的溶解二氧化碳（DCO ₂）水平会突然下降。实施此观察结果是为了设计和开发DCO ₂驱动和控制的重复批发酵工艺以生产乙醇。在四个不同的葡萄糖浓度（〜150 g / L，〜200 g / L，〜250 g / L和〜300 g / L）下测试了该过程，并将每个葡萄糖浓度控制在三个各自的DCO ₂控制水平下（没有DCO ₂控制和DCO ₂控制在1000 mg / L或750 mg / L）。结果表明，所报告的过程具有完全的葡萄糖利用率，并且是自驱动的。对于小于200 g / L的葡萄糖浓度，在重复的批处理操作中，每批发酵可节省〜41％-50％的发酵时间。用葡萄糖进料完成约250 g / L的批次需要12.1±1.1小时-14.9±1.9小时，用葡萄糖进料完成约300 g / L的批次需要21.7±6小时-31.5±7小时。报告的过程节省时间且稳定，但是乙醇收率比没有DCO ₂控制的操作低约20％。如果需要在操作期间每批中的葡萄糖排放量为零，则溶解的CO ₂控制对于葡萄糖浓度大于250 g / L至关重要。