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

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

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

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)

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

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

Small OBB at Newcastle University: Material: Glass Length: 0.5 m Internal diameter: 0.025 m Volume: ~ 2 x 0.35 dm3 Baffle distance: 1.5 D with 0.5 D orifice Second reactor at Newcastle University: Material: Polycarbonate Length: ~ 1 m Internal diameter: 0.05 m Volume: ~ 2 dm3 Baffle distance: 1.5 D with 0.5 D orifice

designed, constructed, commissioned, based at CPI Pilot-scale OBB designed, constructed, commissioned, based at CPI OBB at CPI: Material: 316 dm3 Stainless Steel Length of whole unit: ~ 4 m Internal diameter: 0.05 m Volume: ~ 8 dm3 Baffle distance: 1.5 D with 0.5 D orifice Online monitoring: pH and DO

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

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

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

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

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)

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

Thank you ! Questions?