CONTINUOUS FERMENTATION
P1 P2
So S,X
S,X
Friss tápoldat
f f
V
Friss tápoldat CSTR “leerjedt”
fermentlé P- szivattyú
Cell mass:
ith substrate:
dt f.x V dx
dt V dx
growth
−
=
growth x/S
i i,0
i
dt dx Y
V 1 fS
dt fS V dS
i
−
−
=
V D f =
Dilution rate
FRESH CULT. MEDIUM CSTR FERMENTED
BROTH
P-pump
V D f =
m
3/h m
3h
-11 t
= h
Átlagos tartózkodási időHigítási sebesség Dilution rate
CONTINUOUS FERMENTATION
D t
1 = h
Átlagos tartózkodási időMean residence time
( )
dx
dt x Dx D x S
K S D x
S
= − = − =
+ −
µ µ µ
maxIn steady state
0 dS =
and dx 0
=
( )
dS
dt D S S x
=
0− − µ Y
In the case of one limiting S ( if MONOD model holds ):
Necessary and
enough condition of the steady state
CONTINUOUS FERMENTATION
0 dt =
and dt = 0
D µ
D
= K S
S K
µ S D
max S S
max
⇒ −
= +
( )
x Y S S Y S K D
D
= − = −
S−
0 0
µ
max( )
D S S x
0 − = µ Y
µ=D
CHEMOSTAT
CHEMOSTAT
S x J, , S x,
x x 3
x 2 x 1
J=D
.x
S
S03
S02 S01 S0
tg
CONTINUOUS FERMENTATION
D D
max S
0 0 max
CRITICAL
µ
K S
µ S D
µ ≅
= +
=
Chemostat always operates in substrate limitation Limited balanced growth
(corresponds to the declining phase)
CONTROLL VARIABLES OF THE CHEMOSTAT CONTROLL VARIABLES OF THE CHEMOSTAT
V ONLY TECHNICAL CONSTRAINT
f
CONTINUOUS FERMENTATION
D <<<< µmax=DC
S0 ONLY TECHNICAL CONSTRAINT:
solublity
PRODUCTIVITY:
D 0 J =
∂
∂
[ g/l.h ] or [ kg/m h ]
D.x
J =
3J D x D Y S K D
D
= = −
S−
. .
max
0
µ
= max!!!
− + µ
=
2 / 1 S
max
max
S K
1 K D
CONTINUOUS FERMENTATION
D = 0
∂
( )
[ ]
x
max= Y S
0+ K
S− K S
S 0+ K
S
0+
Smax
max
S K
( )
[ ]
0 max 2
0 S 0
0 S
0 max
S 0
S 0
S 2
/ 1
0 S
S max
max max
max
S S Y
K S
S S K
Y
K S
K S
K S .
K 1 K
Y x
D J
µ
≈
+ −
µ
=
= +
−
+
− + µ
=
=
µ>D
µ=D µ<D
SZAKASZOS
}
INDULÁS
X
Transient behaviour
1.After start: transient from bach to continuous operation
ONLY IN THIS ONLY IN THIS RANGE!!!
RANGE!!!
CONTINUOUS FERMENTATION
Always starts as batch
µ<D
}
TRANZIENS
µ = D
µ=D
t TRANSIENT
CONTINUOUS FERMENTATION
LAG Accelerating phase
exponential phase
declining phase
Steady state
Steady state
Washout
Cont.run starts
Alterations from ideal behaviour
x
D x
D x
D
0,25DC DC
Y
Y
RNS
Y
1 2 3
N,S limitáció Mg2+,K+,PO 3-limitáció
High velocity production of intermediary products
(Pyr,AcOH,...)
D<<<<0,25DC
CONTINUOUS FERMENTATION
limitation limitation
x
D x
D
DC
C/energia limitáció N,S limitáció Mg2+,K+,PO43-limitáció
4
komplex tápoldat-nemkemosztát falnövekedés
( )
5
− −
− −
=
− −
−
−
=
µ m Y
1 Y
1
D µ
D S K
x
µ µx m Y
1 Y
S 1 S
dt D dS
EG C
max S 0
EG C
0
wall growth
limitation limitation
limitation
Cult. Media-nonchemostat
x
D
x
D
0,25DC D Y
RNS
Y
1 3
x
D
Y
2
CONTINUOUS FERMENTATION
D
x
D x
D
D
0,25DC DC
C/energia limitáció
D
N,S limitáció Mg2+,K+,PO43-limitáció
4
komplex tápoldat-nemkemosztát falnövekedés
5
N-forrás, vagy a kénforrás a limitáló tényező Kisebb D-nél a C/en forrás feleslegben van:
Tartaléktápanyagok szintézise
(poliszaharidok,lipidek, β-OH-butirát)
x
D
0,25DC D Y
1
x
D
Y
2 x
D
RNS
Y
3
Mg2+,K+,PO 3-limitáció
CONTINUOUS FERMENTATION
D
0,25DC DC
C/energia limitáció
D
N,S limitáció Mg2+,K+,PO43-limitáció
x
D
falnövekedés
x 5
D 4
komplex tápoldat-nemkemosztát
x
D
falnövekedés
5
Dx = µ x + µ x
fD
C>µ
maxis elérhető!
CONTINUOUS FERMENTATION
( ) ( )
Dx x x
D S S x x Y
f
f x S
= +
− = +
µ µ
µ µ
0
/
/( )
x = Y
x S/S
0− S D x x
= +
f
µ 1
Design of the chemostat
1.Known batch kinetics: µmax, Y, KS D
2.Known batch growth curve (and derivative)
dx/ dt
tg α = µ
maxdx/ dt
tg α = µ
maxA B
CONTINUOUS FERMENTATION
dx/ dt
α
x
dx/ dt
α
x choose D-t, what is x? Choose x,
What is the necessary D?
D D
x
D D
x
Problems
Volume control aeration,foaming
USE OF CHEMOSTAT?
ADVANTAGES: higher productivity balanced, limited growth measurment and control
CONTINUOUS FERMENTATION
measurment and control
SCP, bakers yeast, fodder yeast, (cell mass), primery metabolites:
alcohol, beer research
research: kinetics, optimization,
but: secondery no, though penicillin...in lab scale
T1 T2
T3 OPTIMIZATION
CONTINUOUS FERMENTATION
T: TEMPERATURE CULTURE MEDIA...
CONTINUOUS FERMENTATION
Steady state 2
T: temperature Culture media
pH….
CONTINUOUS FERMENTATION
Steady state 1
Steady state 2
Steady state 3
Fermentation time
One stream, multiple stage
V1
x1
S1
V2
x2 S2
V3
x3
S3 f
S0
f f f
x1S1 x2 S2 x3 S3
1 2 3
CONTINUOUS FERMENTATION
Multiple stream, Multiple stage
V1
x1
S1
V2
x2 S2
V3
x3
S3 f
S0
f1 f2=f1+f02 f3=f2+f03 x1 S1 x2 S2 x3 S3
1 2 3
f02 S02
f03 S03
design:
dx/ dt
tg α = µ
maxα
CONTINUOUS FERMENTATION
x D1
D2
x1 x2 x2x3 D3
CONTINUOUS FERMENTATION
Choosing D
What the outlet will be?
Choosing outlet
What the D will be?
f S0
(1+α)f
(1-α)f x S
Chemostats with recycle
CONTINUOUS FERMENTATION
V
(1-α)f
αf
x S
S
f fX
P Special chemostat: dialysis culture
CONTINUOUS FERMENTATION
S
X Ptáptalaj dializátor fermentor
medium
dialysator
Auxostats
pH-auxostat
CONTINUOUS FERMENTATION
OTHER CULTIVATION METHODS Semicontinuous fermentation
∆ t
142 43xmax
xmin x
xmax = xmineµ∆t vagy ln x = µ∆t x
max min
D V
t V t x
= α = α = αµ
∆ ∆
1
maxln
maxt
t V t x
x
∆ ∆
maxmin
ln
α.V volume taken off
J D x
x x
= . = x ln
max max
min
max
αµ
Other…. TURBIDOSTAT
∆t
xmax
xmin x
t
µµµµ =µµµµmax is possible!!!
dx dt
x t
x x
≅ ∆ = − t
∆ ∆
max min
µ = ≅ =
+
−
1 1 2
x
dx
dt x
x
t x x
x x
t
∆
∆
max min∆
max min
CONTINUOUS FERMENTATION
Flow cell Pump 2
photometer
Controller
Computer Other….: TURBIDOSTAT
Cult medium
Pump 3 Pump 1
broth
x
S1 S2 S3
Application for research: optimization
Other…. TURBIDOSTAT
t
∆t1
∆t2 ∆t3
Other…….fed batch fermentation Fed batch fermentation
Continuation of the declining phase, constant, variable or periodic addition of fresh cult. medium, no broth removalno broth removal..
*keeping low, constant S concentration (Baker’s yeast: glucose
repression, Crabtree effect),
*high constant S concentration (citric acid fermentation)
*precursor continuous addition (penicillin: phenyl-acetic-acid, )
*precursor continuous addition (penicillin: phenyl-acetic-acid, )
pH control!!
Varying volume, f(t)
End of fed bacth
Batch ferm Other…….fed batch fermentation
Vstart ≅ 0,5-0,6 Vtotal Vend ≅0,7-0,85 Vtotal
Batch ferm
Steady state
Feed starts
