What is a fermenter?

• A. A device used for chemical vapor deposition.
• B. Industrial production of ethanol begins as a batch process in these large stainless-steel tanks.
• C. A reactor used for continuous stirred tank.
• D. A plug flow reactor with a catalyst.

Answer: (B)

Fermentation uses living microorganisms to convert substrates into products, so a fermenter is the vessel that provides the right environment—sterility, temperature control, mixing, and sometimes anaerobic or aerobic conditions—for those organisms to grow and produce the desired compound.

Industrial ethanol production typically begins in large stainless-steel tanks where the process is run in batch mode: you load in the sugars, nutrients, and yeast, let fermentation proceed for a set period, and then move on to separation and purification. This setup is characteristic of a fermenter and suits biological processes that require controlled, discrete fermentation cycles.

The other descriptions refer to different types of chemical processing: chemical vapor deposition is a material deposition method, not fermentation; a continuous stirred-tank reactor is a generic reactor used for continuous chemical reactions rather than a batch biological process; and a plug flow reactor with a catalyst is for catalytic chemical reactions in a flow system, not microbial fermentation.