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

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.

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

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

Recovery and Purification of Bio-Products Liquid and solid separation - solid particles: mainly cellular mass, specific gravity 1.05-1.1. size (diameter): bacterial cells: 0.5-3 µm yeast cells: 5 -10 µm mold: 5-15 µm in diameter and 50-500 µm in length animal cells: 10 µm plant cells: 20 µm Methods: .

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

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: 0.1 - 10 µm, bacterial and yeast cells. Size: 10-200 Å, Cell debris, macromolecules

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.

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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.)

Rotary Vacuum Filter

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

Rotary Vacuum Filter t/V V

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):

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

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: 0.1 - 10 µm, bacterial and yeast cells. Ultrafiltration Size: 10-200 Å, Cell debris, macromolecules (antibiotics, proteins, polysaccharides)

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

Liquid-Solid Separation Filtration Centrifugation - Particle size: 100-0.1 µm - more expensive than filtration - limited for scale-up - drive force: centrifugal force

Example The following data were obtained in a constant-pressure unit for filtration of a yeast suspension: t(min) 4 20 48 76 120 V(L) 115 365 680 850 1130 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.