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Lecture 16. Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors in which they take place. Web Lecture 16 Class Lecture 25 – Thursday 4/18/2013. Bioreactors Monod Equation Yield Coefficients - PowerPoint PPT Presentation
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Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of
chemical reactions and the design of the reactors in which they take place.
Lecture 16
BioreactorsMonod EquationYield CoefficientsWashout
2
Web Lecture 16Class Lecture 25 – Thursday 4/18/2013
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Enzymes - Urease A given enzyme can only catalyze only one reaction. Urea is decomposed by the enzyme urease, as shown below.
UREASECONH2UREASECONHNH 23OH
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EPES OH2
SESE 1k SESE 2k
EPWSE 3k
The corresponding mechanism is:
Review Last Lecture
Michaelis Menten Equation
SKSVrr
MSP max
Bioreactors
4
Nutrient (S) + + Productscells more cells
SS
SCg CK
CCr
max
SKSV
rrM
SP max
Bioreactors
5
Batch Bioreactor
6
Phases of Cell Growth and Division
7
inoculum
t=0 time
8Cells + Substrate More Cells + Product
Bioreactors
9
Exponential Growth Phase
Death Phase
Stationary Phase
Lag Phase
0 time
lnCc
a) Phases of bacteria growth:I. Lag II. Exponential III. StationaryIV. Death
b) Monod growth rate law: SS
SCg CK
CCr
max
Bioreactors
VvDLet /0
Bioreactors
10
1) Mass Balances
Accumulation = [In] - [Out] + [Growth] - [Death]
dgCCC VrVrCvCv
dtdCV 000
dgCCC rrCCD
dtdC
)( 1 0
Rate Laws:
3 rg kOBSmaxCS
KS CS
CC
4 kOBS 1 CP
CP*
n
Cp*= Product concentration at which all metabolism ceases11
dgCCC rrCCD
dtdC
)( 1 0
2 dCS
dtD(CS0 CS ) rS
Bioreactors
3) Stoichiometry
SCCS Y
Y'1'
A) Yield Coefficients
cellsnewproducetosubstrateofmassformedcellsnewofmassY SC '
productformtoconsumedsubstrateofmassformedproductofmassY SP '
B) Maintenance
CPSPCSgS mCYrYrr
5 m mass of substrate consumed for maintainence
mass of cellstime
12
Bioreactors
produced) cells of grams(consumed) substrate of grams(' CSY
CPSPCSgS mCYrYrr ''
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3) StoichiometryRate of Substrate Consumption
Can’t separate substrate consumption used for cell growth from that used for product formations during exponenial growth.
CCSgS mCYrr '
Bioreactors
v0
CS0
V=V0vCC
CS
Volume=V
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1) Mass Balance:
(cells) 0 0 VrrCvdtdCV dgC
C
Bioreactors
(product) 3
2
1
rate)(dilution 1
)(substrate
(cells) 0
0
0
000
0
PPP
SSSS
dgCC
SSSS
dgCC
rDCdtdC
rCCDdtdC
rrDCdtdC
VvD
VrCvCvdtdCV
VrrCvdtdCV
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Bioreactors
2) Rate Laws:
4 rg maxCS
kS CS
CCKOBS
5 KOBS 1 CP
CP*
n
6 rP YP /Crg
7 rS YS /Crg mCC
8 rD kDCC
3) Parameters
VDVvCvmCvmCDmyykknC
PpC
SCPCSDSP
, , , , , , , , , , , ,
000
0//*
max
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Bioreactors
1.) d(CC)/d(t)=-D*CC+(rg-rd)2.) d(CS)/d(t)=-D*(CS0-CS)-Ysg*rg-m*CC
3.) d(CP)/d(t)=-D*CP+YPC*rg
4.) rg=(((1-(CP/Cpstar))**0.52)*mumax*(CS/(KS+CS))*CC5.) D=0.26.) kd=0.017.) rd=kd*CC
8.) CS0=2509.) YPC=5.610.) m=0.3
11.) mumax=0.3312.) YSC=12.513.) KS=1.7
Polymath Setup
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Bioreactors – Chemostats - CSTRs
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CCSS
SgC CC
CKCrDC
max
SS
S
CKCD
max
1. Steady State - Neglect Death Rate and Cell Maintenance
VrDVC gC 02. Cell
DDKC S
S
max
D
DKCYCCYC SSSCSSSCC
max00
VrVCCD SSS 00
CCSgCSSSS DCYrYrCCD //0
3. Substrate
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Bioreactors – Chemostats - CSTRs
CSTR Washout
0
0max
SS
SW CK
CD
0CC
CCc DC
VCv
Vm
0
D
DKCDYDC SSSCC
max0
CC
DW
D
CC
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Washout dilution rate
Bioreactors – Chemostats - CSTRs
Maximum Product Flow Rate
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How does this figure relate to drinking a lot of fluids when you have an infection or cold?
0SS
0SmaxW CK
CD
0SS
Smaxprodmax CK
K1D
DCC
DW
DDmaxprod
End of Web Lecture 16End of Class Lecture 25
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