SOLID-LIQUID SEPARATION: FILTRATION · Processing Course. FILTRATION THEORY 1 A dV dt = ......
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SOLID-LIQUID SEPARATION: FILTRATION Charles L. Cooney Downstream Processing Course
Transcript of SOLID-LIQUID SEPARATION: FILTRATION · Processing Course. FILTRATION THEORY 1 A dV dt = ......
SOLID-LIQUID SEPARATION: FILTRATION
Charles L. CooneyDownstream
Processing Course
FILTRATION THEORY
1A
dVdt
=∆P
µ(Rm + Rc)
Poiseulle’s Law
Filtration RateBroth Viscosity
Resistance to Flow
V=filtrate volumeA=Filter areat=Time∆P=Pressure Driving Forceµ=Broth viscosityW=Mass of filter cakeR=Resistanceα=Specific cake resistanceS=Compressability factor
Rm =αW
A
Cake Resistance
α = α' ∆PSSpecific Cake Resistance
The filter resistance is much less than the cake resistance
Rc<<Rm
1A
dVdt
=∆P
µ(α ' ∆P S WA )
When the filter cake is incompressible, S=0
1A
dVdt
=∆P
µ(α ' WA )
When the filter cake is very compressible, S=1.0
1A
dVdt
=1
µ(α ' WA )
Flocculation of CellsSedimentation Rate
VS =dp
2(ρp − ρs )18µ
gc
Filtration Rate
20VSPk
dtdV ∆
=
S0=K’(1/Dp)2
S02 = K’’/Dp
4
VPDk
dtdV p
40∆=
Mechanism of Flocculation
• Particle bridging• Charge neutralization• Charge patch
neutralization
- -
- + -
1. Repulsion F1- F2 (1-x1)(1-x2)-
F1+ F2 x1(1-x2)-
F1- F2 (1-x1)x2
+
F1
K1 K2
+ F2 x1x2+
2. Attraction
3. Attraction
4. Repulsion
Langmuir Isotherm
x =Species 1Divalent Ion
Species 2 =NNa
- + -
- + -+
SK+S
Net Force Force Magnitude
+
+
++
+
Figure by MIT OCW.
Recovery of Penicillin G from 200 m3 Fermentation
Flocculants Broth 200 m3 batch
Rotary Filter30 m2x2
Biomass disposal 98%
97%
96%
99.2%
99.8%
99.4%
Penicillin (5990 kg) + solvent
Penicillin (5760 kg) + solvent
Penicillin G K+
salt (5350 kg)
Penicillin G K+ salt (5340 kg)
Penicillin G K+ salt(5300 kg)
Penicillin G K+
salt recovery
Penicillin G recovery
Extraction
CentrifugationAcetone Wash
Potassium Acetate
Vacuum Dry
Penicillin G 5000 kgBiomass 6000 kg dry wt
Figure by MIT OCW.
