Question

4. Lactobacillus casei is propagated under essentially anaerobic conditions to provide a starter culture for manufacture of Swiss cheese. The culture produces lactic acid as a by-product of energy metabolism. The system has the following characteristics:
YXS=0.23 kg/ kg
KS=0.15 kg m3
μmax=0.35 h-1
mS=0.135 kg/ kg/ h

A stirred fermenter is operated in fed-batch mode under quasi-steady-state conditions with a feed flow rate of 4 m3/ h and feed substrate concentration of 80 kg m3. After 6 h,the liquid volume is 40 m3.
(a) What was the initial culture volume?
(b) What is the concentration of substrate at quasi-steady state? [​

Answer 1

Explanation:

Lactobacillus casei is propagated under essentially anaerobic conditions to provide a starter culture for manufacture of Swiss cheese. The culture produces lactic acid as a by-product of energy metabolism. The system has the following characteristics: Yx/s 0.23 kgkg Ks0.15 kg/m Hmax 0.35/h ms 0.135 kg/kg.h A stirred fermenter is operated in fed-batch mode at quasi-steady state witha feed flow rate of 3 m/h and feed substrate concentration of 60 kg/ m3. After 6 h, the liquid volume is 30 m3.