2) A 200L fermenter is used for batch cultivation of Bacillus subtilis bacteria. Air at 20C is introduced into the fermenter at a rate of 1 vvm (volume of air per volume of medium per minute). The pressure in the fermenter is 1 atm. The volumetric outflow rate of the fermenter gas is 189 L/min. The outgoing gas stream is analyzed for O2 and contains 20.1% O2. The solubility of O2 in the fermenter is 7.8 10-3 kg/m3. The oxygen concentration in the culture medium is 52% of the saturation concentration. Calculate:

a) the rate of oxygen transfer b) the value of KLa for the system