Part 2b: Fermenter Design and Operation Flashcards
Give some advantages of batch culture
Contamination will only lead to the loss of one batch
Fermenter can be used for different purposes after sterilisation
Give some advantages of continuous culture
The growth rate can be controlled
Biomass can be held in exponential growth phase for extended periods of time, making it more efficient than batch culture
Give some disadvantages of batch culture
Higher labour costs
Down time between batches is required
Less efficient than continuous culture
Give some disadvantages of continuous culture
Contamination can cause much more damage
Fermenter can only be used for one process
What is the purpose of a sparger
Provides oxygen for microbial respiration
What is the purpose of an impeller
Mixing to provide homogeneity
What is the purpose of baffles
Additions to bioreactor’s inner walls to increase turbulent flow
What is the purpose of antifoam
Reduces foam build up due to fermentation
What is the purpose of temperature and pH controls
Keep the cell environment at optimal conditions for cell growth
What is the result of increasing a bioreactor’s height
Increased hydrostatic pressure:
Improves oxygen (and other gases) solubility
May cause compartmentalisation
What is the result of increasing a bioreactor’s diameter
Lowers superficial gas velocity:
Lower mixing
Lower oxygen transfer
Poor temperature control
Def: Agitation
Mixing
Def: Aeration
Providing sufficient oxygen to meet metabolic demands
What are the consequences of using a rushton impeller
Good oxygenation
Moderate mixing
High shear
What are the consequences of using a pitched impeller
Lower oxygenation
Good mixing
Lower shear
