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Approximation of continuous fermentation by semicontinuous cultures.
1Department of Chemical Engineering, Purdue University, West Lafayette, Indiana, 47907, USA.
Biotechnology and Bioengineering
|March 5, 1990
Summary
Semicontinuous fermentations can approximate continuous growth. A new model reveals that deviations depend on feed concentration, replacement rate, and time between replacements, enabling better approximation of continuous cultures.
Area of Science:
- Biotechnology and Biochemical Engineering
- Microbial Fermentation Processes
Background:
- Semicontinuous fermentation is a method to approximate continuous growth by periodically replacing a portion of the culture with fresh media.
- Existing models, like Fencl's, often inaccurately estimate deviations from continuous operation, as they assume specific growth rate is independent of substrate concentration.
Purpose of the Study:
- To develop and test a novel approach for modeling semicontinuous fermentation that incorporates standard kinetic expressions.
- To accurately simulate semicontinuous fermentations and compare their behavior to continuous growth under various conditions.
Main Methods:
- Developed a new modeling approach for semicontinuous growth, integrating kinetics applicable to batch and continuous cultures.
- Tested the model using Monod's expression for specific growth rate.
- Utilized a dimensionless form of the model to simulate semicontinuous fermentations and analyze deviations from continuous growth.
Main Results:
- The study identified three key dimensionless variables influencing the differences between semicontinuous and continuous growth: feed concentration, replacement rate, and time between replacements.
- Simulations demonstrated that specific ranges of these dimensionless variables allow semicontinuous cultures to closely approximate continuous growth.
Conclusions:
- The developed model provides a more accurate representation of semicontinuous fermentation dynamics compared to previous methods.
- Understanding the interplay of dimensionless feed concentration, replacement rate, and time between replacements is crucial for optimizing semicontinuous processes to mimic continuous ones.
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