Sef Heijnen,DepartmentofBiotechnology,FacultyofAppliedSciences

AerobicPDOprocess:improvingsustainability

Theprocessscheme

Rp=165000molPDO/h

FN,in =3361320 (mol/h)yO2,in =0.2100yw,in =0yCO2,in=0

FN,NH3 =35970 (mol/h)

Gastransfer:O2 =433207mol O2/hNH3 =35970mol NH3/hH2O=225658mol H2O/hCO2 =607200mol CO2/h

FN,out =3760969 (mol/h)yO2,out =0.0725yCO2,out =0.1614yw,out =0.0600ptop =1bar

Fm,out (kg/h)=54920kg/h

Fm,in (kg/h)=71225kg/h

Heat=51434kJ/s

35°C

Broth mass =2250tonne

Moresustainable: “pushingthelimits”Less consumption/production permolPDOofeverything

- Lower coefficientsintheprocess reaction (lower variable cost)

Lower DSPcost:Higher PDOconcentration inbroth- Glucoseinfeedatsolubilitylimit

Lower capital cost:Smallerfermenters- HighO2 transportrate inthefermenter:week4- LowO2/PDOratioinprocess reaction

Lower qi/qp ratios:Dissect theprocessreaction

4 2 2 26 12 6 4 2 1 1.8 0.5 0.2 3 8 2 2 2*C * * * 1* * * * ( )NH O CO H O Qs H

p p p p p p p p

q q q q q qq H O NH O C H O N C H O CO H O H heatq q q q q q q q

µ+ ++ ++ + + + + + + +

μ/qp ·Biomass reaction+

(+1)· PDOreaction+

(-ms/qp)· Glucosecatabolism

Minimizecoefficientsby increasingqp

0.04

0.03

0.02

0.01

00.005 0.010 0.015 0.02 0.025 0.03 0.0350

Lowering qi/qp ratios:thekinetic approachbyincreasing qp by metabolic engineering

μ (h-1)q p

0.05 0.10μopt 0.025 0.014qp,opt 0.023 0.059

(=α)

qs/qp 1.295 0.95μ /qp 1.09 0.24qO2/qp 2.63 1.42cs,opt 85·10-6 192·10-6

qp,max

Metabolicengineering

Wildtype Mutant

LimitofincreasingqpProcess reaction

BBmodelPDOreactionisthelowerlimit

BBmodelPDOreaction-0.80C6H12O6-0.80O2 +1.00C3H8O2 +1.80CO2 +H2O

PDO

strongincreasing qp

1.4

1.2

1.0

0.8

0.6

0.4

0.2

00.1 0.2 0.3 0.4

qp

mol s/mol p

BBmodelPDOreaction

Lowering qi/qp ratios:thestoichiometric approachofmetabolic engineering

PDOreaction oftheBlackBoxmodel:-0.80C6H12O6-0.80O2 +1.00C3H8O2 +1.80CO2 +0.80H2O

Catabolic part:-0.80/6C6H12O6 -0.80O2 +0.80/6CO2 +0.80/6H2O

Anabolic part,“substract catabolic partfrom PDOreaction”:-0.666C6H12O6 -0O2 +1.00C3H8O2 +1CO2 +0H2O

• Improved ATPproduction /O2• Less ATPconsumption /molPDO• …?

Limitofstoichiometricapproachofmetabolicengineering:Anaerobic holy grailStoichiometric approach:decrease O2 stoichiometry0.80molO2 /molPDO

Theoretical PDOreaction-0.6666C6H12O6– 0O2 +1C3H8O2 +1CO2 +110kJGibbsenergy

à 0?

Limitofstoichiometricapproachofmetabolicengineering:Anaerobicholygrail

TheoreticalPDOreaction-0.6666C6H12O6– 0O2 +1C3H8O2 +1CO2 +110kJGibbsenergy

Compare:TheoreticalEthanolreaction-0.50C6H12O6+1C2H6O+1CO2 +112kJGibbsenergy

AnaerobicPDOprocessinprinciplepossible- Moresustainable!!

LowerDSPcost:focusonless water

→ Moreconcentrated glucosesolution: operate atglucosesolubility limit

→ waterfreefeedstock• Ethanol• Methanol• H2/COsyngas

→ Highfermentation temperature to increase waterevaporation

HighPDOconcentration

Fromsustainablefeedstocks

BigBanana:usemassnotvolumeForpreviouscalculationsweusedthevolumeapproach:

- Concentrationsinmol/l- BrothvolumeVL(m3)- Volumebalance

However:- Volumeconservationdoesnotexist: 1lwater+1lethanol≠2lmixture- Massconservationholds: 1kgwater+1kgethanol=2kgmixture

Recommendedapproach:- Defineconcentrationinmol/kgliquid- UsethetotalbrothmassMinthefermenter- UsethetotalmassbalancetocalculateFm,out (kg/h,seePDOcase)- Frommasscompositionandthermodynamicdensitycorrelationyoucancalculatedensity,

volumeoutflowandbrothvolumeVL

Whichisincorrect,minorerrorindilute systems

Seeyouinthenextunit!