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Unformatted text preview: Biological Reactions
Bioreactors Biological reactions that involve micro-organisms and enzyme catalysts are
pervasive and play a crucial role in the natural world. Bioreactions are performed in a “bioreactor”: • • • Without such bioreactions, plant and animal life, as we know it, simply
could not exist.
Bioreactions also provide the basis for production of a wide variety of
pharmaceuticals and healthcare and food products.
and healthcare and food prod Chapter 2 Chapter 2 • (1) batch reactor
• (2) fed-batch reactor = semi-batch reactor
• (3) mixed-flow reactor (MFR or CSTR = continuously stirred tank reactor).
• Fed-batch is a synonym for semi-batch.
• Fed-batch reactors are widely used in the pharmaceutical
reactors are widely used in the pharmaceutical
and other process industries.
• Mixed-flow reactors are used in continuous processes, such as waste water
treatment ponds and high production rate facilities. Important industrial processes that involve bioreactions include
fermentation and wastewater treatment. • A bioreactor can be a PFR = a plug flow reactor, for example with
• Chemical engineers are heavily involved with biochemical and biomedical
engineers are heavily involved
biochemical and biomedical
processes. supported biocatalysts attached to inert spheres
bi SEMD3: Fed-Batch Bioreactor Bioreactions S = Substrate(food) = (N = “Nutrient” g/liter)
Nutrient g/liter) Cells = X = (“Bugs” = B = Organism g/liter) • Yield / Maintenance Coefficients:
Y= g of new cells produced
g of food consumed to produce new cells M= g of food for maintenance / h
g of bugs in reactor Monod Equation: Chapter 2 Chapter 2 cells
substrate → more cells + products (g bugs produced/h)/liter rg = μ B Specific Growth Rate (1/h)
μ = μmax N
Ks + N Figure 2.13 Fed-batch reactor CHE 361 Dynamics
for a bioreaction
---> Mixed Flow Reactor
From SEMD3 text. For continuous production CHE 361 Project is a Mixed-Flow Reactor: MFR or CSTR
Continuous Stirred Tank Reactor A Constant Volume MFR/CSTR or a “Chemostat” dB
"Bug" Mass Balance
= Ni − N −
− M B "Nutrient" Mass Balance
⎟ = an "intermediate" variable.
KS + N ⎠
F and N i are the process inputs, V = 1.00 L = volume μ = μ max ⎜ At the nominal steady state:
the nominal steady state: ⎛
N = KS ⎜
⎟ and B = Y ( N i − N ) ⎜
⎝ F /V + M Y ⎠
⎝ μ max − F / V ⎠ Choices: 4 Process Kinetic Parameters from Ranges 0.001 - 0.2 (g food/h) / g bugs = base metabolic rate μmax 0.1 - 3.0 (1/h) = maximum growth rate Y 0.2 - 0.7 (g bugs / g food used to produce bugs) =
food used to produce bugs)
nutrient growth efficiency Ks 0.2 - 10. (g food / liter) = growth food sensitivity Choices: 2 Nominal Steady-state Input Value Ranges
Input Value Ranges F = 0.5 to 5 liters / h
N i = 1 to 100 g / liter
li Chapter 4 M For the bioreactor, there are
2 outputs, thus you must use
2 ODEs : balances for “bugs”
ODEs balances for bugs
and for “nutrient” in the reactor. ...
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