lecture 3 bioprocess control
DESCRIPTION
TRANSCRIPT
14th. July 2010CEPP, UTM Skudai, Johor
Prof. Dr. Hesham A. El EnshasyFaculty of Chemical Engineering
CEPP, UTM, Skudai, Malaysia
Bioprocess Control(On-line, off-line and in-line)
Parameters for measurements and control for cultivation system
Cell Input and Cell out-put (conditions and nutrients requirements)
Sensors used for bioreactors
Main Items of Presentation
Feed back loops for bioprocess control
Summary screen for different control system
SCADA system for control using ethernet platform
Cell In-put and Cell Out-put
CELL
Oxygen
Carbon and Energy
Sources
Nitrogen Source
Other requirements(P, S,Na,K,Mg,etc…)
Carbon dioxide
Biomass
Metabolite(s)
Water
Heat
Substrate(s) Input and Output
Physical Chemical Biological - Temperature- Bioreactor Pressure (St. St. Bioreactors)- Agitation Speed- Gas Flow rate - Total volume- Feeding rate- Power Input- Foam
- pH- Dissolved oxygen
- Cell Morphology- Cell viability- Optical Density - Cell Dry weight- Cellular composition- Specific growth rate- Specific substrate(s) consumption rates. - Specific production rate
- Reactor weight- Feeding tank weight- Culture Viscosity- Gas Hold up - Gas Mixing pattern
- Dissolved carbon dioxide- Redox potential- Out gas analysis (O2, CO2, N2)- Substrate(s)- Product(s)- Enzyme activities- Volatile compounds- Conductivity - Biomass composition (C,H,O,N,P,S)- Metabolite profiling- Mineral Ions
- Oxygen uptake rate- Carbon dioxide production rate- RQ- Growth inhibitors - Protein - DNA / RNA- ATP / ADP / AMP
Different Parameters for cultivation system
Integrated of Mathematical Methods for Advanced Process Control Ref. (Clementschitsch and Bayer. Microbial Cell Factories 5:19 (2006)
Input and Output of Bioreactor system (General overview)
Main in situ sensors used for measuring cultivation parameters
Culture parameters Sensor Range Accuracy
Temperature Pt-100 0-150C 0.1C
Pressure Piezoresistor 0-2 bar 20 mbar
Gas flow Thermal mass flow meter
Upto 2 v v-1 minBased on bioreactor volume
0.1%
pH pH electrode 2-12 0.02
pO2 Polarografic electrode
0-400 mbar 2 mbar
pCO2 Membrane covered pH electrode
0-100 mbar 2 mbar
Feed pump(s)
Temperature
Aeration
Power consumption
Stirrer Speed
Exhaust gasAnalyzer
pH
DO
Pressure
Weight / volume
Measurement and open or closed loop control
Measurement only
Common measurement and control of bioreactors as generally accepted as routine equipment
Lower ports for in situ sterilizable STR
Applicationmeasurement
Lower ports Upper ports Headplate ports
Temp./pH/DO/ DCO2/ Turbidity probes/substrate (s) on-line
+ (for pilot scale bioreactors)
- + (only for small scale bioreactors / Glass bioreactors)
Pressure gauge orPressure sensor
- - +
Line to outgas analysis - - + (after condenser and out-gas fileter)
Feeding / acid-based / Antifoam addition
- Highly suitable(Small scale pilot)Less Suitable (Large scale)
Highly suitable(Large scale)Less Suitable (Small scale pilot)
Harvest (Continuous Culture)(Repeated batch)
+ - -
Sampling + - -
Upper/lower ports and Headplate
pH values of different liquids
pH and hydrogen ion concentration
pH measuring circuit and pH meter construction
Temperature Effect on pH value
Temperature Error Table
DO meter construction
The relation between DO and Temperature
Standard Antifoam Sensor
Foam sensors: Low foam sensor High foam sensor
Type of foam: Early foaming Late foaming
Antifoam effects on: DO Growth morphology (Filamentous MO)
On-line cell mass determination methods
Principle Advantages Disadvantages
Optical density Wide linear range Some interference
Culture fluorescence Measurement of cellular activity
Singanal interpretation is difficult
Capacitance Wide measurement range
Measurement of cellular activity
Interferance from aeration and aerationSignal interpretation is difficult
Ultrasonic Wide linear range
Self cleaning
Interference from aeration and agitationTemperature sensitive
On-line cell mass and viability measurement
Theory:
Cells with intact plama membranes act like tiny capacitors under the influence of electric field. The nonconducting nature of plasma membranes allows charge to build up. The resulting capacitance can be measured and is usually expressed in picofarad per centimeter (pF/cm). It depends on the cell type and is directly proportional to membrane bound volume of viable cells.
Stat-culture Sensor Controlled variables
pH-Stat pH electrode (online) Acid-based
DO-Stat DO electrode (online) AerationAgitationOxygen (optional)
Nutri-Stat(Chemo-Stat)
nutrient sensor (on-line), Off-line analyzer (online), FIA (online)
Feeding substrate (s)
Turbidistat Turbidity meter (online) Feeding substrate(s)Harvest pump
QO2 and QCO2 Stat
Out-gas analyzer (in-line)
AerationAgitationOxygen (Optional)Feeding substrate(s)
Controlling stat-culture
Feedback control: A control algorithm to reduce the error between the set point and the controlled variable (most often PID or model predictive controller algorithm is used)
Feedforward control: A computation of the manipulated variable from a measurement of the disturbance (most often corrected by a PID or model predictive controller)
Feedback and Feedforward controllers
Basic feedback loops for a fungal culture for antibiotic production
Basic feedback loops for microbial high cell density formation
Bioreactor Input and Output for basic PID control feed
Connections to USB, controller software and Ethernet for SCADA
Supervisory Control and Data Acquisition syste (SCADA)
Thank You