Fermentation is a biochemical process in which a carbohydrate-such as the sugar glucose-is converted by bacteria or yeast to an organic compound-such as ethanol-and carbon dioxide. The process is best known for its use in making beer, wine, and other alcoholic beverages, but it is also used to produce a wide range of other industrially important chemicals. The diagram below shows a continuous fermentation process. An aqueous solid-liquid slurry containing a carbohydrate and bacteria enters a stirred tank where it undergoes fermentation.
Fermentation products, including species condensed from the off-gas, and bacteria are withdrawn from the tank. A mixer with multiple rotating impellers keeps the solids in the tank suspended in the liquid. An air stream enters the fermenter through a sparger (something like an inverted shower head) designed to produce small bubbles that rise through the mixture and remove the CO2 formed in the reaction. Some of the oxygen in the air fed to the fermenter is consumed by the bacteria. The gas products go through a condenser, which condenses most of the water and returns it to the fermenter, and the uncondensed off-gas goes to a dryer and then to a mass spectrometer, where its composition is determined. The flow rate of the air feed is measured to be 0.600 SLPM (liters per minute at standard temperature and pressure) and the measured compositions of the air and the offgas are shown on the diagram. The off-gas is at 28°C and 1.1 atm.

Describe in your own words the purpose of this process and the functions of the mixer, the air, and the sparger.

Fermenter off-gas (28C, 1.1 atm) To dryer and mass spectrometer 17.3% O, 3.55% CO, MIXER MOTOR 78.7% N2 CONDENSER 0.45% G Carbohydrate Bacteria Note: "G" in the flowchart denotes a mixture of H,O(v) and other gases. Fementation products 0.600 SLPM 20.7 mole% O2 0.033% CO2 Bacteria 77.9% N2 SPARGER 1.4% G