Instrumentation and control Parameters: to be monitored and controlled Temperature Pressure Agitator shaft power Flowrate Liquid level Viscosity Turbidity pH Redox potential Ion concentration DO Read pages 308-310 in the text book.

Summary of Bioreactor Design and Operation Modified batch and continuous reactors - Chemostat with cell recycle Keep high cell mass concentration in the reactor. Production of biomass and low-value product - Fed-batch Maintain low substrate concentration Secondary metabolites, prevent catabolite repression - Multi-stage chemostat reactor Separate cell growth and product formation Secondary metabolites, genetically modified cell culture

Summary of Bioreactor Design and Operation Modified batch and continuous reactors - Chemostat with cell recycle (qp=0, kd ≈0, X0=0, Monod equation is applied):

Summary of Bioreactor Design and Operation Modified batch and continuous reactors - Fed-batch (qp=0, kd ≈0, Monod equation is applied):

Summary of Bioreactor Design and Operation Modified batch and continuous reactors - Multi-stage chemostat reactor

Summary of Bioreactor Design and Operation Immobilized cell system Advantages and disadvantages Operation consideration agitation and aeration, determination of volumetric mass transfer coefficient kLa, heat removal, foam, etc.

Summary of Bioreactor Design and Operation Scale up/down: geometric and dynamic similarity: In scale-up/down of a stirred-tank reactor, the design calculations are as follows: Determine the scale-up/down factor Dp/Dm Calculate the dimensions of the prototype (height H and diameter Dt of tanks, impeller diameter Di) by multiplying that of the model with the scale-up/down factor. - Select criterion related to dynamic properties and keep it constant in both the model and the prototype. - Determine the parameters such as impeller speed for the scale-up/down reactor.

Summary of Bioreactor Design and Operation Sterilization liquid: thermal inactivating 1- P0(t)= 1-[1-e-kdt]N0 kd = αe-E0d/RT From the above equation: Known N0, T, t, determine Kd, the probability of an unsuccessful sterilization is determined. Given N0, T, acceptable probability of failure e.g. 10-3, required time can be determined Higher Kd tends to achieve low probability of sterilization failure. Normally at 121oC. Kd of vegetative cells > 1010 min-1, spores 0.5-5 min-1. The major concern is spores.

Summary of Bioreactor Design and Operation Sterilization Degradation of important compounds in the medium by thermal inactivating ln C/C0=-kdt where C and C0 are concentrations of the component at time t and t=0, respectively. kd is the degradation rate constant. kd = αe-E0d/RT To determine the components remaining active: the temperature T → determine kd → with known t, determine C.

Summary of Bioreactor Design and Operation Bioreactor Instrumentation and control