#Question id: 14318
#Part-B Specialized Branches in Biotechnology
system for manufacture of single-cell protein is Methylophilus methylotrophus. This organism is produced aerobically from methanol with ammonia as nitrogen source. The molecular formula for the biomass is CH 1.6800.36N0.22; these cells contain 6% ash. If the actual yield of biomass from methanol is 42% the thermodynamic maximum, what is the oxygen demand?
#Question id: 14331
#Part-B Specialized Branches in Biotechnology
To ensure turbulent conditions and minimum mixing time during agitation with a turbine impeller, the Reynolds number must be at least 104. A stirred laboratory-scale fermenter with a turbine impeller 5 cm in diameter is operated at 800 rpm. If the density of broth being stirred is close to that of water, what is the upper limit for viscosity of the suspension if adequate mixing is to be maintained?
#Question id: 14332
#Part-B Specialized Branches in Biotechnology
To ensure turbulent conditions and minimum mixing time during agitation with a turbine impeller, the Reynolds number must be at least 104. A stirred laboratory-scale fermenter with a turbine impeller 5 cm in diameter is operated at 800 rpm. If the density of broth being stirred is close to that of water. The mixing system is scaled up so the tank and impeller are 15 times the diameter of the laboratory equipment. The stirrer in the large vessel is operated so that the stirrer tip speed (tip speed = π N i D i) is the same as in the laboratory apparatus. How does scale-up affect the maximum viscosity.
#Question id: 14333
#Part-B Specialized Branches in Biotechnology
A cylindrical bioreactor of diameter 3 m has four baffles. A Rushton turbine mounted in the reactor has a diameter one third the tank diameter and is operated at a speed of 90 rpm. The density of the fluid is approximately I g cm-3. The reactor is used to culture an anaerobic organism that does not require gas sparging. The broth can be assumed Newtonian. As the cells grow, the viscosity of the broth increases. when the viscosity is 1000 times greater than water, estimate the power required to achieve turbulence.
#Question id: 14334
#Part-B Specialized Branches in Biotechnology
Laboratory-scale fermenters are usually mixed using small stirrers with electric motors rated between 100 and 500 W. One such motor is used to drive a 7cm turbine impeller in a small reactor containing fluid with the properties of water. The stirrer speed is 900 rpm. Estimate the power requirements for this process.
#Question id: 14336
#Part-B Specialized Branches in Biotechnology
A cylindrical stirred bioreactor of diameter and height 2 m has a Rushton turbine one-third the tank diameter in size. The bioreactor contains Newtonian culture broth with the same density as water and with viscosity 4 cP. The tank is now aerated. In the presence of gas bubbles, the approximate relationship between ungassed power number (NP)0 and gassed power number (NP)g is: (NP)g =0.5 (NP)0. What maximum stirrer speed is now possible in the sparged reactor? Estimate the mixing time.