1. 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)

2. Bioprocesses?
microbes have a multitude of biochemical and metabolic abilities
Escherichia coli (Bacterium, 1 µm long)
6,000 genes
2,000 enzymes.

5. 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.

6. Programme Topics materials processing energy production
waste processing and bioremediation
corrosion resistance
production of drugs
manufacture of polymers.

7. Programme Topics materials processing?
oxidation of reduced sulphur minerals to yield sulphuric acid and dissolved metals.

8. Programme Topics
energy production?
ethanol
(biodiesel)
methane.

9. Programme Topics waste processing and bioremediation?
liquid organic wastes to methane-rich biogas
biological wastewater treatment.

10. Programme Topics production of drugs? antibiotics
secreted heterologous products?
e.g. proteins
plant cell metabolites?.

11. 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.

12. Attachment and Biofilm Formation
Ethanol-producing bacterium: Zymomonas mobilis
Ethanol-producing yeasts: Saccharomyces cerevisiae (top) S. diastaticus (bottom)

13. 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

14. 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.

15. No Biomass Support Medium? = unstable

17. Static Bed
zero to low
flow

18. Expanded Bed
(< 100%)
medium
flow
zero to low
flow

19. Fluidized Bed
(> 100%)
medium
flow
zero to low
flow
high
flow

20. Transition from static to expanded bed, as pump switched on

21. Expanded bed: note retention of bioparticles

22. Expanded bed: biofilm thickness control

23. Pilot-scale (0.6 m3 expanded bed)

24. Full-scale package plant (10 m3 expanded bed)

25. Enzyme & Biodiesel Production
Early biofilm-formation in pores of glassy coke:
transesterase-producing, thermophilic bacteria.

26. Fuel Ethanol production
Ethanol-producing bacterium: Zymomonas mobilis
(thick biofilm on glassy coke)

27. Fuel Ethanol production

28. Fuel Ethanol production

29. Shewanella putrefaciens bioparticles for wastewater treatment

30. Biocatalysis. e. g. with mono-oxygenase
Biocatalysis? e.g. with mono-oxygenase? (ammonia mono-oxygenase producer)

31. 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.