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10_Bio_modelsW12 - Biological Reactions • Bioreact...

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Unformatted text preview: Biological Reactions • Bioreact 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 pharmace 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) Substrate(food) 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 of for maintenance g of bugs in reactor Monod Equation: Chapter 2 Chapter 2 cells • Bioreactions: 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 FB =μB− "Bug" Mass Balance dt V dN F F μB = Ni − N − − M B "Nutrient" Mass Balance dt V V Y ⎛ ⎞ N ⎟ = 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: ⎛ ⎞ ⎛ ⎞ F /V F /V 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) = (g 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 Nominal Steady Input Value Ranges F = 0.5 to 5 liters / h N i = 1 to 100 g / liter 100 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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