10_Bio_modelsW12 - Biological Reactions • Bioreact...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

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. ...
View Full Document

This note was uploaded on 03/01/2012 for the course CHE 361 taught by Professor Staff during the Winter '08 term at Oregon State.

Ask a homework question - tutors are online