21. Heat transfer rates (per unit volume) will be lowest in

A. Stirred tank bioreactor with biomass recycle
B. Continuous airlift bioreactor
C. Continuous packed bed reactor
D. Continuous fluidized bed bioreactor

22. The function(s) of the draft tube in an airlift bioreactor is

A. to reduce bubble coalescence
B. to improve circulation
C. to even out shear conditions throughout the reactor
D. all of the above

23. The Monod Model relates

A. substrate utilized with the biomass consumption
B. specific growth rate to the substrate availability
C. yield with the biomass utilization
D. the biomass concentration with the specific growth rate

24. The height to diameter ratio (H/D) for the column fermenters is

A. <3
B. >3
C. <1.5
D. >1.5

25. The high oxygen transfer efficiencies of airlift bioreactors is due to

A. the large aspect ratio of the reactor, which leads to a high gas hold-up
B. the large aspect ratio of the reactor, which leads to a high oxygen solubility at the base of the reactor
C. the draft tube, which reduces bubble coalescence in the reactor
D. all of the above