Final answer:
The cell settler in yeast cultivation with a Continuous Stirred Tank Fermenter is used for cell separation, allowing recycling of cells and thereby enhancing biomass productivity by keeping cultures in the rapid logarithmic growth phase.
Step-by-step explanation:
The purpose of the cell settler in a Continuous Stirred Tank Fermenter (CSTF) with cell recycling during yeast cultivation is primarily for A. Cell Separation. This process allows for the yeast cells to be separated from the culture medium. The separated cells can then be recycled back into the system, promoting higher biomass productivity by maintaining a high cell density within the reactor. By doing so, it ensures that the yeast cultures remain in the logarithmic phase of growth which is the phase during which growth occurs at the fastest rate. Moreover, factors such as nutrient availability and toxic waste accumulation limit microbial growth, hence the need for a cell recycling system like a cell settler to efficiently manage the cell density and nutrient supply within the cultivation process.