1. Oscillatory Baffled Reactors for Biological Applications
Claudia Tröger
School of Chemical Engineering and Advanced Materials
Newcastle University
April 2008

2. Oscillatory Baffled Reactors (OBR)
Contrast to the conventional plug flow reactor:
equally spaced orifice plate baffles
tubular reactor divided into single chambers
Oscillation causes the formation of vortices
radial and axial mixing
chambers each act like a single stirred tank reactor
intensive, uniform mixing with low shear
mixing intensity described by oscillatory Reynolds number taking into account frequency and amplitude of the oscillation
Necessary Reynolds number to achieve turbulence only needs to be 1/8th of the conventional size

3. Oscillatory Baffled Reactors (OBR)
Practical, compact design
Plug flow
Effective two-phase liquid mixing
Enhanced heat transfer
Enhanced mass transfer
Uniformity of mixing, low shear
Process intensification by replacement of a batch reactor with a continuous OBR
Reduced energy consumption:
reduced running costs
Smaller reactor:
reduced capital costs
Scale-up understood & predictable
Process advantages:
STR
Product tank
OBR
Feed tanks

4. Niche Application of the OBR
Conversion of long residence time batch processes to continuous processing
Possible applications:
Fermentations: enhanced KLa value demonstrated (75 %)(Ni et al., 1995)
2. Crystallization: control of crystal size and shape (paracetamol)(Ristic, 2007)
3. Suspension polymerisation: narrower particle size distribution (Ni et al., 1999)
4. Photochemical effluent treatment: catalyst particle suspension, gas-liquid
contacting (Fabiyi and Skelton, 1999)

5. BIOPRODUCTION
European Project for the Sustainable Microbial and Biocatalytic Production of Advanced Functional Materials using Renewable and Waste Resources
14 European countries:
7 small and medium enterprises (SME’s)
4 large companies
6 research centres
6 university departments
Aim:
Development of new sustainable bioprocesses for the production of functional products such as lactic acid- and polyhydroxyalkanoate-(PHA)-based polyesters, biopolymers and polysaccharide-based surfactants

6. Aims of this PhD project
Development of a laboratory scale intensified bioreactor namely an Oscillatory Baffled Bioreactor (OBB) for the efficient and cost-effective production of bio-materials at high yields
Design of a laboratory-scale OBB capable of operating under sterile conditions
Fabrication and commissioning of this OBB
Construction of a pilot-scale OBB at CPI, Wilton
Evaluation of the OBB for producing
biobased chemicals and biopolymers

7. Small OBB at Newcastle University:
Material: Glass
Length: m
Internal diameter: m
Volume: ~ 2 x 0.35 dm3
Baffle distance: D with 0.5 D orifice
Second reactor at Newcastle University:
Material: Polycarbonate
Length: ~ 1 m
Internal diameter: m
Volume: ~ 2 dm3
Baffle distance: D with 0.5 D orifice

8. designed, constructed, commissioned, based at CPI
Pilot-scale OBB
designed, constructed, commissioned, based at CPI
OBB at CPI:
Material: dm3 Stainless Steel
Length of whole unit: ~ 4 m
Internal diameter: m
Volume: ~ 8 dm3
Baffle distance: D with 0.5 D orifice
Online monitoring: pH and DO

9. Test Fermentations (Bioethanol Production using Yeast)
Evaluation of cell growth and conversion as functions of
time, temperature and mixing intensity (Reo)
Monitoring of yeast growth and ethanol production:
to investigate yeast behaviour in the OBB
to determine the potential for decreasing the fermentation time

10. Results Cell growth rate as a function of oscillatory Reynolds number,
a measure of mixing intensity (different Reo at 27 °C)

11. Ethanol % over time for different Reo and temperatures
Results
Ethanol % over time for different Reo and temperatures
Comparison at ethanol content 4 %

12. Ethanol production curve at 32 ˚C for two different agitation rates
Results
Ethanol production curve at 32 ˚C for two different agitation rates

13. Conclusions
Evaluation of cell growth and conversion as functions of time,
temperature and mixing intensity:
Agitation influences yeast growth positively
A higher Reynolds number promotes cell growth
Fermentation rate was increased by increasing temperature and
agitation
Ethanol could be successfully produced with a significant reduction
in time-to-completion (10 % to 20 % of conventional process time)

14. Future Work
Develop OBB design further using the results of the yeast case study
Determine whether the advantages can be successfully exploited
for producing biobased chemicals and biopolymers
Extended work to investigate the production of:
A. Biosurfactants:
Evaluate the performance of the OBB for:
the partial hydrolysis of polysaccharides
the esterification of oligosaccharides through enzymatic
hydrolysis, in terms of reactor productivity and enzyme stability
B. Novel functionalised polyesters:
Evaluate the OBB for productivity enhancement in the production of novel functionalised polyesters

15. Thank you !
Questions?