A stream of growth medium containing 60% glucose and 40% growth factor A flowing at 500 kg per hour was divided into two feed streams for different cell cultures. One fourth of the growth medium was sent to fermenter 1 and the rest was sent to fermenter 2. What is the flow rates of glucose and growth factor A in the feed streams for the two fermenters

#Question id: 14240

#Section 5: Bioprocess Engineering and Process Biotechnology

A 200-1itre stirred fermenter contains a batch culture of Bacillus subtilis bacteria at 28⁰C Air at 20⁰C is pumped into the vessel at a rate of 1 vvm; (vvm stands for volume of gas per volume of liquid per minute). The average pressure in the fermenter is 1 atm. The volumetric flow rate of off-gas from the fermenter is measured as 189 l min^-1. The exit gas stream is analysed for oxygen and is found to contain 20.1% 0₂. 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 28⁰C and 1 atm air pressure is 7.8 x 10^-3 kg m^-3. Determine the value of k_La for the system ____________

#Question id: 14241

#Section 5: Bioprocess Engineering and Process Biotechnology

Yeast cells are to be separated from a fermentation broth. Assume that the cells are spherical with diameter 5 µm and density 1.06 g cm^-3. The viscosity of the culture broth is 1.36 x 10^-3 N s m^-2. At the temperature of separation, the density of the suspending fluid is 0.997 g cm^-3. 500 litres broth must be treated every hour. Specify Σ for a suitably-sized disc-stack centrifuge

         ____________________

#Question id: 14242

#Section 5: Bioprocess Engineering and Process Biotechnology

Small food particles with diameter 10^-2 mm and density 1.03 g cm^-3 are suspended in liquid of density 1.00 g cm^-3. The viscosity of the liquid is 1.25 mPa s. A tubular-bowl centrifuge of length 70 cm and radius 11.5 cm is used to separate the particles. If the centrifuge is operated at 10 000 rpm, estimate the feed flow rate at which the food particles are just removed from the suspension. ____________________

#Question id: 14243

#Section 5: Bioprocess Engineering and Process Biotechnology

A tubular-bowl centrifuge is used to concentrate a suspension of genetically-engineered yeast containing a new recombinant protein. At a speed of 12 000 rpm, the centrifuge treats 3 l broth min^-1 with satisfactory results. It is proposed to use the same centrifuge to separate cell debris from homogenate produced by mechanical disruption of the yeast. If the average size of the debris is one-third that of the yeast and the viscosity of the homogenate is five times greater than the cell suspension, what flow rate can be handled if the centrifuge is operated at the same speed? _____________________

#Question id: 14244

#Section 5: Bioprocess Engineering and Process Biotechnology

Ethanol is produced by anaerobic fermentation of glucose by Saccharomyces cerevisiae. For the particular strain of S. cerevisiae employed, the maintenance coefficient is 0.18 kg kg^{- 1} h^{- 1}, Yxs is 0.11 kg kg^-1, Y_PX is 3.9 kg kg^-1 and µ_max is 0.4 h^-1.  It is decided to investigate the possibility of using Zymomonas mobilis bacteria instead of yeast for making ethanol. Z. mobilis is known to produce ethanol under anaerobic conditions using a different metabolic pathway to that employed by yeast. Typical values of Yxs are lower than for yeast at about 0.06 kg kg^-1; on the other hand, the maintenance coefficient is higher at 2.2 kg kg ^-1 h ^-1. Ypx for Z. mobilis is 7.7 kg kg^-l; µ_max is 0.3 h- 1.  From stoichiometry, what is the maximum theoretical yield of ethanol from glucose