Expanded Bed Technology for High-rate Bioprocesses
Mike Dempsey School of Biology, Chemistry, & Health Science Manchester Metropolitan University and Advanced Bioprocess Development Ltd. (an MMU spin-out company) Bioprocesses? microbes have a multitude of biochemical and metabolic abilities Escherichia coli (Bacterium, 1 m long) 6,000 genes 2,000 enzymes. Expanded Bed Technology
fluid-based processing normally liquid gas-phase possible processing of liquids pure or solutions grow cells in nutrient liquid and replace with feedstock or feedstock solution, whilst retaining cells in bioreactor particulates. Programme Topics materials processing energy production
waste processing and bioremediation corrosion resistance production of drugs manufacture of polymers. Programme Topics materials processing?
oxidation of reduced sulphur minerals to yield sulphuric acid and dissolved metals. Programme Topics energy production? ethanol (biodiesel) methane. Programme Topics waste processing and bioremediation?
liquid organic wastes to methane-rich biogas biological wastewater treatment. Programme Topics production of drugs? antibiotics
secreted heterologous products? e.g. proteins plant cell metabolites?. Expanded Bed Technology
method of process intensification 10-fold increase in biomass concentration 10-fold decrease in bioreactor size fixed biofilm system no need for biomass recovery & recycle natural immobilization on glassy coke naturally-adhesive microbes biomass retention cheap media expanded bed does not clog no backwashing. Attachment and Biofilm Formation
Ethanol-producing bacterium: Zymomonas mobilis Ethanol-producing yeasts: Saccharomyces cerevisiae (top)S. diastaticus (bottom) Particulate Biofilm Technology
fixed film process method of process intensification retention of biomass by attached growth attachment to support particles microbes grow as a biofilm formation of particulate biofilms biofilm coke Biomass Support Medium: Glassy Coke
carbonized bituminous coal light (SG 1.2) carbon-based (90% C + 10% ash) porous (interconnecting pores: carbon foam) initial colonisation of pores overgrowth to form complete biofilm sand heavy (SG 2.65) & non-porous. No Biomass Support Medium? = unstable Static Bed zero to low flow Expanded Bed (< 100%) medium flow zero to low flow Fluidized Bed (> 100%) medium flow zero to low flow high flow Transition from static to expanded bed, as pump switched on Expanded bed: note retention of bioparticles Expanded bed: biofilm thickness control Pilot-scale (0.6 m3 expanded bed) Full-scale package plant (10 m3 expanded bed) Enzyme & Biodiesel Production
Early biofilm-formation in pores of glassy coke: transesterase-producing, thermophilic bacteria. Fuel Ethanol production
Ethanol-producing bacterium: Zymomonas mobilis (thick biofilm on glassy coke) Fuel Ethanol production Fuel Ethanol production Shewanella putrefaciens bioparticles for wastewater treatment Biocatalysis. e. g. with mono-oxygenase
Biocatalysis? e.g. with mono-oxygenase? (ammonia mono-oxygenase producer) Summary generic technology with wide variety of applications
fluid-based processing liquid (or gas) fluidization of small particles causes bed expansion attachment of microbes to particles; growth as biofilm high biomass concentration excellent mixing and mass transfer highly active biomass high-rate, compact process technology.