1. Recovery and Purification of Bio-Products
Strategies to recovery and purify bio-products
Solid-liquid separation
Cell disruption
Separation of soluble products
Finishing steps for purification

2. Recovery and Purification of Bio-Products
Strategies to recovery and purify bio-products
Unique characteristics of bioseparation products:
- the products are in dilute concentration in an aqueous medium. e.g therapeutic protein 0.01mg/l.
- The products are usually temperature sensitive.
- There is a great variety of products to be separated.
- The products can be intracellular, often as insoluble inclusion bodies.
- The physical and chemical properties of products are similar to contaminants.
- Extremely high purity and homogeneity may be needed for human care.

3. Recovery and Purification of Bio-Products
Strategies to recovery and purify bio-products
Fementer
Solid-liquid separation
Recovery
Purification
Supernatant
Cells
Cell products
Cell rupture
Cell debris
Crystallization and drying

4. Recovery and Purification of Bio-Products
Strategies to recovery and purify bio-products
Fementer
Solid-liquid separation
Recovery
Purification
Supernatant
Cells
Cell products
Cell rupture
Cell debris
Crystallization and drying

5. Recovery and Purification of Bio-Products
Liquid and solid separation
- solid particles: mainly cellular mass, specific gravity
size (diameter):
bacterial cells: µm
yeast cells: µm
mold: 5-15 µm in diameter and
µm in length
animal cells: 10 µm
plant cells: 20 µm

6. Recovery and Purification of Bio-Products
Liquid and solid separation
Solid particles: mainly cellular mass
Methods: filtration and centrifuge

7. Liquid-Solid Separation Filtration
Physical separation of solid particles from liquid or gas.
a porous medium: allow fluid to pass through
solid particles to be retained.
Slurry flow
Filtrate
Filter medium
Filter cake

8. Liquid-Solid Separation Filtration
Rotary vacuum filtration
Particle size: greater than 10 µm, yeast, mold, animal or plant cells.
i.e. mycelium separation for antibiotics production or waste water treatment
Microfiltration
Particle size: µm, bacterial and yeast cells.
Ultrafiltration
Size: Å, Cell debris, macromolecules

9. Rotary Vacuum Filter
A rotary vacuum filter is a continuous filter partially submerged
in the slurry.
- A drum is covered with a filter medium.
Vacuum is applied to within the drum
As the drum rotates,
The solid constituent is separated by retained on the porous medium
The liquid is drawn through the cake
into the inner filtrate pipes.
Each revolution consists of cake formation,
cake washing (if required),
drying and cake discharge.

10.
VacuumFilters/vacuum.htm
Filtration/RotaryVac.html

11. Rotary Vacuum Filter
The rate of filtration (the flow of the filtrate) for a constant pressure (vaccum) filtration operation can be determined by

12. Rotary Vacuum Filter

13. Rotary Vacuum Filter
Assuming incompressible cake: constant α, & constant pressure,
and integrating the previous equation (V at t, V=0 at t=0) yields
t/V V

14. Rotary Vacuum Filter To design a scaled-up rotary vaccum filter
If given a total volume of fermentation broth Vb and
required time tb to complete the filtration task at the large scale,
determine the filter surface area.
Based on the results from the smaller filter
(incompressible cake: same α, medium & pressure drop):

15. Rotary Vacuum Filter
Relating the design equation to the rotation speed
In a rotating drum filter,
The drum rotates at a constant speed (n rps)
Only a fraction of drum-surface area is immersed
in suspension reservoir (φ)
Ruth equation can be rewritten as

16. Liquid-Solid Separation Filtration
Rotary vacuum filtration
Particle size: greater than 10 µm, yeast, mold, animal or plant cells.
i.e. mycelium separation for antibiotics production or waste water treatment
Microfiltration
Particle size: µm, bacterial and yeast cells.
Ultrafiltration
Size: Å, Cell debris, macromolecules

17. Liquid-Solid Separation Filtration
Microfiltration
Particle size: µm, bacterial and yeast cells.
Ultrafiltration
Size: Å, Cell debris, macromolecules (antibiotics, proteins, polysaccharides)
Use membrane as porous medium for filtration.
Challenge: gel formation on the surface of membrane.
Solution: cross-flow (tangential flow filtration)
Pressure P1
Pressure P2
Feed in
Feed out

18. Liquid-Solid Separation Filtration
Centrifuge
- Particle size: µm
- more expensive than filtration
- limited for scale-up
- drive force: centrifugal force