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© 2016 Centre for Process Innovation Limited. All Rights Reserved.
Scale up/scale down strategies and
devices16/11/2016
Valentina Mangiafridda MEngGas Lab and Fermentation Manager
CPI mission
We use applied knowledge in science and engineering combined with
state of the art facilities to enable our clients to develop, prove,
prototype and scale-up the next generation of products and
processes.
Industrial Biotechnology and Biorefining
How is it possible to give solid and reliable
answers to scale up challenges at early
research stage?
The instrument we need should help us
• ... to forecast process results in Demo scale
• ... to mimic and predict the client manufacturing scale processes
• ... to easily increase the consistency in process performance through process characterisation
• ... to evaluate the scalability of our process in development
Challenges covered with Scale Down Model (SDM) Approach
750L
5/10/20L 1L1mL
Scale Down Model Design
• Bioprocesses performances are multiphase systems: gas-liquid, or three-phase;
• Mass transfer between the phases controls process kinetics.
Scale Down Model Design
• The approach is based on the mass transfer uniformity among the scales
• Its aim is to have the same kLa during the process to transfer
• This must accurately reproduce the event of a process (pH drifting, media sterilisation
peculiarities, parameters control inefficiencies, etc..)
Scale Down Model Design
The data collected and analyses are:
�Bioreactor design & Mass Transfer performances
�Process parameters (setpoint & controls)pO2, Air Flow, stirrer speed, pH, Head pressure, Temperature, ...
�Fermentation batchDynamic behaviour of the process
�Growth curves
�OutputProduct, Metabolites, Impurities (with a Kinetic study during the process)
INP
UT
OU
TP
UT
Bibl. Villadsen at al., Bioreaction Engineering Principles, 2011
Scale Down Model Design
Impeller performances with gas dispersion retrofit comparison
Bakker A. 2006 Fermenter Specific Modeling Issues www.bakker.org
SDM step-by-step
Collect the Bioreactor design and
KLa data
Analysis on the
geometrical
parameters
Bioreactor set up and re-
design
Mixing
Characterization
Comparison of kLa method
determination and values
Culture conditions to apply in the
new bioreactor
• A rigorous approach need to be
followed to de-risk a bioprocess
technical transfer
Example – rProtein production in E. coli
The SDM aim is to have the same kLa across scales
Scale (L) Gas velocity(m/s)
Maximum impeller speed (RPM)
Harvest OD600 Protein Yield (g/L)
kLa (s-1)
2 2.6 x 10-3 1200 75 4.2 ± 0.1 0.12
20 5.6 x 10-3 1000 66 4.6 ± 0.5 0.10
200 1.2 x 10-2 500 51 1.3 ± 0.1 0.06
P. Farrell et al. / Vaccine 30 (2012) 5695– 5698
Scale (L) Gas velocity(m/s)
Maximum impeller speed (RPM)
Harvest OD600 Protein Yield (g/L)
kLa (s-1)
2 2.6 x 10-3 880 50 1.8 ± 0.4 0.06
20 5.6 x 10-3 580 46 1.2 ± 0.1 0.06
200 1.2 x 10-2 500 51 1.3 ± 0.1 0.06
CPI case study (750L → 20L)
750L20L
750L batch fermentation to replicate on the 20L SDM
GC of 750L vs 20L SDM
The most used method is the Dynamic Gassing-out method
How measure the kLa?
( ) XqCCakdt
dCoALL
ALAL 2*
−−=Slope: kLa
Process values to to apply during the ABSORPTION:
- Stirrer Speed
- Inlet gasses flow
- Temperature
- Pressure
kLa= f(stirrer speed, inlet gasses flow)
Question
Tech- Transfer based Project for the scale-up of aerobic process for enzyme production
at 750L.
• The client performed in 1L scale the process at maximum stirrer speed and Air flow with
remarkable results in terms of Oxygen supply during the C-source feeding
• The KLa in these condition is 240 h-1
• The maximum KLa achievable in 750L is 175 h-1.
Which Issue can we forecast?
The direct scale up will show a severe Oxygen limitation, with
• production of side-products
• Riduction of productivity in large scale
Run Lost!!
Question
Aim: To define scalable Fed-batch aerobic process for enzyme production at 750L.
• The maximum KLa achievable in 750L is 175 h-1.
Study will be focus on Glucose profile and the effect to DOT control at defined mass transfer in
5L bioreactor.
• The mass transfer condition will be scaled down to 5L
• Which conditions will give a KLa of 175 h-1?
5L Mixing Characterisation Results
80
400
800
0
50
100
150
200
250
0.15
0.5
1
Stirr
er
Speed (
rpm
)
KLa (
h-1
)
Air Flow (vvm)
Internal CPI dataKLa in 5LWV @0.2 bar 37degC
0-50 50-100 100-150 150-200 200-250
Gas-liquid flow regimes
Bakker A. 2006 Fermenter Specific Modeling Issues www.bakker.org
Time for your calculations
0
50
100
150
200
250
300
0 200 400 600 800 1000
KLa (
h-1
)
Stirrer Speed (rpm)
KLa dep. Stirrer Speed
0.1 vvm
0.5 vvm
1 vvm
0
50
100
150
200
250
300
0 0.2 0.4 0.6 0.8 1 1.2
KLa (
h-1
)
Air Flow (vvm)
KLa dep. Air Flow
80 rpm
400 rpm
800 rpm
Time for your calculations
y = 0.323x - 4.5344R² = 0.9775
0
50
100
150
200
250
300
0 100 200 300 400 500 600 700 800 900
KLa (
h-1
)
Stirrer Speed (rpm)
KLa dep. Stirrer Speed
0.1 vvm
0.5 vvm
1 vvm
• The maximum Air flow
in 750L is 1vvm
• 175h-1 can be reached
with 556rpm
Solution
– The Scale Down Model limit the stirrer speed and air flow cascade ranges to 556rpm
and 1vvm
– The C-source feeding will be reduced once reached the DOT set point
– The C-source feeding will be scaled up as compromise for a continuous enzyme
production in presence of sufficient Oxygen
Other features….
• SDM information to be integrated with the CFD analysis, in order to fully
understand the overall mass transfer distribution in the bioreactor.
Bakker A. 2006 Fermenter Specific Modeling Issues www.bakker.org
Other features….
• In SDM scale the variability of your model &
process can be determinate.
• Process optimisation and Process
Characterisation can be done with DoE studies in
that scale.
1L1mL
Summary
• Bioprocesses are prone to mixing related performance problems:
– Gas dispersions can never be homogenous.
– Mass transfer will limit productivity or affect process control.
• A rigours model needs to be establish to forecast common issues typical of large scale
bioreactor
• Scale down model (SDM) kLa based can help to
– to evaluate the scalability of our process in development
– to forecast process results in Demo scale
• Coupled with CFD and DoE Model, represent the next step for a completer understanding
of Mid-stream steps in bioprocesses
Demonstration in the lab
KLa
• Validate results of the previous question: 556rpm and 1vvm will give a kLa of 175h-1?
Thank you...For more information, please visit www.uk-cpi.com
Email:
Twitter:
info@uk-cpi.com
@ukCPI
www.uk-cpi.com
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