1. Recovery and Purification of Bio-Products (Chapter 11, M
Recovery and Purification of Bio-Products (Chapter 11, M. Shular, textbook)
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 concentration in an aqueous medium. e.g therapeutic protein 0.01mg/l.
- The products are usually sensitive.
- There is a of products to be separated.
- The products can be , often as insoluble inclusion bodies.
- The physical and chemical properties of products are similar to contaminants.
- Extremely 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
Methods:

6. 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

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

8. 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.

9.
VacuumFilters/vacuum.htm
Filtration/RotaryVac.html

10. Rotary Vacuum Filter
The rate of filtration (the flow of the filtrate) for (vaccum) filtration operation can be determined by (Bennet &Myers, Momentum, Heat and Mass Transfer, 1974, p221, the equation is from the mass balance of the cake.)

11. Rotary Vacuum Filter

12. Rotary Vacuum Filter
Assuming incompressible cake: constant α & constant pressure.
Integrating the following equation (V at t, V=0 at t=0) yields

13. Rotary Vacuum Filter
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 For incompressible cake: constant α.
If filtration rate is constant,

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
(antibiotics, proteins, polysaccharides)

17. Liquid-Solid Separation Filtration
Microfiltration & Ultrafiltration
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
Centrifugation
- Particle size: µm
- more expensive than filtration
- limited for scale-up
- drive force: centrifugal force

19. Example
The following data were obtained in a constant-pressure unit for filtration of a yeast suspension:
t(min)
V(L)
Characteristics of the filter are as follows:
A=0.28m2, C=1920kg/m3, μ=2.9X10-3 kg/m-s, α=4m/kg
Determine:
a) The pressure drop across the filter.
b) The filter medium resistance.
c) The size of the filter for the same pressure drop to process 4000L of cell suspension in 20 min.