1 /17Prado, O.A; Jørgensen, S.B. and Jonsson, G.

MODELING REVERSE ELECTRO-ENHANCED DIALYSIS FOR INTEGRATION WITH LACTIC

ACID FERMENTATION

Oscar Andrés Prado Rubio, Sten Bay Jørgensen and Gunnar Jonsson

C A P E C

Department of Chemical and Biochemical EngineeringTechnical University of Denmark

NPCW09, Jan 29-30, 2009

2 /17Prado, O.A; Jørgensen, S.B. and Jonsson, G.

• Introduction and motivation• REED process• REED module modelling• Simulation results - static analysis

- dynamic analysis• Conclusions

Outline

Introduction and motivationREED process

REED module modellingSimulation Results

Conclusions

3 /17Prado, O.A; Jørgensen, S.B. and Jonsson, G.

Lactic acid productionAlternativesProcess description

Why Lactic acid production?pH regulator, emulsifying agent, animal feed supplement, solvent, electrolyte and Polylactic acid

?Synthetically by hydrolysis of lactonitrile

Fermentation of carbohydrates by Lactic Acid Bacteria (LAB)

Introduction and motivationREED process

REED module modellingSimulation Results

Conclusions

Applications Demand

Design Operation

4 /17Prado, O.A; Jørgensen, S.B. and Jonsson, G.

How can it be done?

Due to LAB are impaired by lactates, continuous removal of biotoxic lactate will intensify the process

Starting point:

Precipitation

Solvent extraction

Adsorption

Direct distillation

Membrane separation processes

Studied alternative:

Integrated bioreactor with electrically driven membrane separation processes

Substrate

BioreactorMembrane separation processes

Broth +Lactate

Broth

Lactic acid

80% costs downstream

- Very selective- Aseptic- No by-products

Introduction and motivationREED process

REED module modellingSimulation Results

Conclusions

Lactic acid productionAlternativesProcess description

5 /17Prado, O.A; Jørgensen, S.B. and Jonsson, G.

Continuous Reverse Electro-Enhanced Dialysis (REED) process

• In situ lactate removal

Introduction and motivationREED process

REED module modellingSimulation Results

Conclusions

Lactic acid productionAlternativesProcess description

Model based study for optimization of the design and operation

• Operation at higher cell densities

• Facilitates the pH control

6 /17Prado, O.A; Jørgensen, S.B. and Jonsson, G.

Driving forces:

Concentration and potential gradients across the membranes

Potential problems of electrically driven MSP

• Divalent cations

• Low fluxes in DD

• Fouling in ED and DD

Definition:

Module with AEM where the current is periodically reversed

Only AEM

Imposing electrical field

Current reversal – Destabilization of fouling

What is REED?

Introduction and motivationREED process

REED module modellingSimulation Results

Conclusions

REED descriptionHow REED works

7 /17Prado, O.A; Jørgensen, S.B. and Jonsson, G.

Introduction and motivationREED process

REED module modellingSimulation Results

Conclusions

REED descriptionHow REED works

8 /17Prado, O.A; Jørgensen, S.B. and Jonsson, G.

OH–

OH–

L–

BL IIZone 3

BL IZone 1

AEM IZone 2

Feed bulk

Dialysate bulk

Na+

Na+

x = 0 x = x1 x = x3x = x2

L–

OH–

L–

BL IVZone 6

BL IIIZone 4

AEM IIZone 5

Feed bulk

Na+

x = x4 x = x5 x = x7x = x6

x-direction

y-di

rect

ion

ProteinsSubstrate

ProteinsSubstrate

REED cell descriptionModellingModel tuning

Cell in the REED stack

Convective transport in y-direction

Diffusion and migration in x-direction

CSTR in series model

Irreversible thermodynamics approach

Introduction and motivationREED process

REED module modellingSimulation Results

Conclusions

Phenomena involved: simultaneous diffusion, convection, electrophoretic transport of ions, plus ion dissociation and equilibrium at the membrane surface

9 /17Prado, O.A; Jørgensen, S.B. and Jonsson, G.

Mass balances:

p kk k k k

dC F dJ D z C

dx RT dx

, 0k p pk k

CJ R

t

Flux: Nernst-Planck

1 1s sz z

m m

a a

a a

Equilibrium at the interface: Model:

Solution: Asymmetric 7-point difference equations System of DAE’s

7

,,

1o

feedfeed feed in feedk

k k k k k px x x xfeed feed

qdCC C J J R

dt h LW h

Conditions:

•Electroneutrality

•Current carried by ions

•No accumulation at the interfaces

System of multiregion PDAE

Introduction and motivationREED process

REED module modellingSimulation Results

Conclusions

REED cell descriptionModellingModel tuning

10 /17Prado, O.A; Jørgensen, S.B. and Jonsson, G.

,( , )m s dia ink k OHD f D C

Introduction and motivationREED process

REED module modellingSimulation Results

Conclusions

REED cell descriptionModellingModel tuning

Prado Rubio, O.A. et al. Lactic Acid Recovery in Electro-Enhanced Dialysis: Modelling and Validation. Accepted to ESCAPE-19.

Estimated parameters:

11 /17Prado, O.A; Jørgensen, S.B. and Jonsson, G.

AEM1 AEM2

Dialysate

Feed Feed

An

od

e (

+) C

ath

od

e (-)

OH-

L-

L-

OH- OH

-

L-

Na+

Na+

Na+

Introduction and motivationREED process

REED module modellingSimulation Results

Conclusions

Competitive ion transportFluxes enhancementOperation under current reversal

,( , )dia ind OHI f C

12 /17Prado, O.A; Jørgensen, S.B. and Jonsson, G.

Max Donnan Dialysis flux

Saturation of the current

Introduction and motivationREED process

REED module modellingSimulation Results

Conclusions

Total lactate fluxes imposing an external potential gradient

Sonin, A. and Grossman, G. (1972). Ion Transport through Layered Ion Exchange Membranes. Journal of Physical Chemistry, 76(26), 3996-4006.Prado Rubio, O.A. et al. Lactic Acid Recovery in Electro-Enhanced Dialysis: Modelling and Validation. Accepted to ESCAPE-19.

Competitive ion transportFluxes enhancementOperation under current reversal

13 /17Prado, O.A; Jørgensen, S.B. and Jonsson, G.

Pseudo-steady state

Maximum separation Donnan dialysis

Introduction and motivationREED process

REED module modellingSimulation Results

Conclusions

( , , )diap d OH revN f I C t

3 3 2100 / ; 50 / ; 5min; 100 /feed diaLac OH rev dC mol m C mol m t I A m

Competitive ion transportFluxes enhancementOperation under current reversal

14 /17Prado, O.A; Jørgensen, S.B. and Jonsson, G.

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

0.0035

0.004

0 10 20 30 40 50 60 70 80 90

Reversal time (min)

Lac

tate

rec

ove

ry (

mo

l/m

in)

Max recovery

Concentration profiles are almost developed

Price of long time operation ?

Introduction and motivationREED process

REED module modellingSimulation Results

Conclusions

Competitive ion transportFluxes enhancementOperation under current reversal

DD max recovery

15 /17Prado, O.A; Jørgensen, S.B. and Jonsson, G.

0

5000

10000

15000

20000

25000

0 10 20 30 40 50 60 70 80 90

Reversal time (min)

En

erg

y co

nsu

med

(K

J) (

max

per

iod

)

0

10

20

30

40

50

60

Po

ten

tial

gra

die

nt

(V)

Energy

Potential

Zone where it will be unfeasible to operate at constant current density

Maximum potential gradient

Operation: constant ΔV → J↓

Introduction and motivationREED process

REED module modellingSimulation Results

Conclusions

Competitive ion transportFluxes enhancementOperation under current reversal

From experimental data

( ( ))f R t

16 /17Prado, O.A; Jørgensen, S.B. and Jonsson, G.

•A dynamic model was derived from first principles for simultaneous transport of multiple ions across ion exchange membranes under current load conditions (including current reversal conditions).

•The model has been tuned based on experimental data for dialytic recovery of monoprotic carboxylic ions.

•The model is used to understand the competitive ion transport across anions exchange membranes under current load conditions.

•The potential flux enhancement by imposing an electrical field is calculated. Lactate fluxes are increased up to 230% compared to Donnan dialysis operation.

•Investigations of REED show that an optimal operating point represents a trade off between lactate recovery and energy consumption, subject to constraints.

•This model is derived as a tool to optimize the design and operation of the REED module when it becomes integrated with a bioreactor for lactic acid production.

Introduction and motivationREED process

REED module modellingSimulation Results

Conclusions

17 /17Prado, O.A; Jørgensen, S.B. and Jonsson, G.

Thanks for your attention....Your questions are welcome!References

Fila, V. and Bouzek, K. (2003). A Mathematical Model of Multiple Ion Transport Across an Ion-Selective Membrane under Current Load Conditions. Journal of Applied Electrochemistry, 33, 675-684.Hongo, M.; Nomura, Y. and Iwahara, M. (1986). Novel Method of Lactic Acid Production by Electrodialysis Fermentation. Applied and Environmental Microbiology, 52(2), 314-319.Møllerhøj, M. (2006). Modeling the REED Process. Master’s thesis, Technical University of Denmark.Prado Rubio, O.A.; Jørgensen, S.B. and Jonsson, G. Lactic Acid Recovery in Electro-Enhanced Dialysis: Modelling and Validation. Accepted to ESCAPE-19.Rype, J. (2003). Modelling of Electrically Driven Processes. Ph.D. thesis, Technical University of Denmark.Sonin, A. and Grossman, G. (1972). Ion Transport through Layered Ion Exchange Membranes. Journal of Physical Chemistry, 76(26), 3996-4006.Zheleznov, A. (1998). Dialytic Transport of Carboxylic Acids through an Anion Exchange Membrane. Journal of Membrane Science, 139, 137-143.

Acknowledgments:

This project is carried out within the Bioproduction project which is financed by the 6th Framework Programme, EU.