question 4?

4. A 200 -liter stirred fermenter contains a batch culture of Bacillus subtilis bacteria at 28C. Air at 20C is pumped into the vessel at a rate of 1vvm; (vvm stands for volume of gas per volume of liquid per minute). The average pressure in the fermenter is 1atm. The volumetric flow rate of off-gas from the fermenter is measured as 189Lmin1. The exit gas stream is analysed for oxygen and is found to contain 20.1%O2. The dissolved-oxygen concentration in the broth is measured using an oxygen electrode as 52% air saturation. The solubility of oxygen in the fermentation broth at 28C and 1atm air pressure is 7.8103 kgm3 (a) (5 points) Calculate the oxygen transfer rate. (b) (5 points) Determine the value of kL a for the system. (c) (5 points) The oxygen analyser used to measure the exit gas composition has been incorrectly calibrated. If the oxygen content has been overestimated by 10%, what error is associated with the result for kLa