Unit V
Unit V: Bioreactors for Suspension and Immobilized Cultures
Overview
Understanding various bioreactor types is crucial for fermentation or enzyme conversion processes.
Focus on microbial and immobilized cell systems.
Key Concepts
Strategies for Choosing a Bioreactor: Consider reactor configuration, size, processing conditions, and mode of operation.
Types of Bioreactors:
Airlift Bioreactor
Fluidized Bed Bioreactor
Membrane Bioreactor
Photobioreactor
Biofilm Reactor
Single-use Bioreactors
Page 2: Strategies for Choosing a Bioreactor
The reactor is essential in fermentation processes.
Design involves scientific, engineering principles, and rules:
Reactor Configuration: e.g., stirred tank vs. air-driven vessel.
Reactor Size: Determines production rate.
Processing Conditions: Temperature, pH, oxygen control, and contamination prevention.
Mode of Operation: Continuous vs. batch processing, substrate feeding strategies.
Page 3: Cost-Determining Factors
Key Focus Areas:
Maximize product yield, concentration, purity, and productivity.
Minimize reactor size, costs, and contamination risk.
Optimize conditions, improve strain and media.
Page 4: Bioreactor Types by Size
Bioreactor choice influenced by culture volume:
Small-scale: <1 L (parallel units for screening)
Bench-scale: 1-10 L (classic for assays and processing)
Pilot-scale: >10 L (typically stainless steel, automated cleaning).
Page 5: Temperature and Sterilization
Adequate volume for samples, minimized evaporation losses.
Sterilization in bench-scale bioreactors using steam; single-use vessels possible.
Page 6: Novel Bioreactors
Types include pneumatically agitated, membrane reactors, and photobioreactors.
Page 7: Immobilized Cells and Enzymes
Definition: Confinement of cells without losing biological activity.
Bio-Encapsulation: Cells immobilized in microcapsules.
Applications: Cell immobilization for diverse reactions.
Page 8: Requirements for Immobilization
Desired characteristics include high mass-loading, ease of nutrient access, simple procedures, and biocompatibility.
Page 9: Active Immobilization
Methods:
Covalent binding and cross-linking.
Advantages: Enhanced stability and durability, control over process.
Page 10: Passive Immobilization
Methods: Entrapment and adsorption; easier processes with less risk.
Applications: Temporary immobilization for research.
Page 11: Classification of Immobilized Cell Systems
Based on physical localization (e.g., surface attachment, encapsulation) and microenvironment.
Page 12: Adsorption Methods
Various methods (monolayer, biofilm proliferation) for cell attachment.
Page 13: Design of Immobilized Cell Reactors
Mass transfer impact on reactor performance.
External vs. internal mass transfer limitations.
Page 14: Types of Immobilized Cell Bioreactors
Overview of reactor types used for immobilized cells.
Page 15: Three-Phase System
Bioreactors typically have solids, liquid, and gas phases.
Oxygen transfer is critical, especially in aerobic processes.
Page 16: Thiele Modulus and kLa
Important for designing and scaling bioreactors.
Page 17: Packed-Bed Reactors
Features packing catalytic materials in columns for substrate flow.
Page 18: Membrane and Packed Bed Issues
Potential clogging and challenges in regulation.
Page 19: Fluidized Bed Reactor
Solid particle fluidization for optimal mixing and mass transfer.
Page 20: Sections of Fluidized Bed Reactor
Describes the layout and function of FBR sections.
Page 21: Flow Regimes in FBR
Different gas-liquid dynamics affecting performance.
Page 22: Advantages and Disadvantages of FBR
Summary of operational benefits and potential drawbacks.
Page 23: Airlift Reactor
Characteristics of airlift design, useful for shear-sensitive cultures.
Page 24: Parts of an Airlift Reactor
Components and their functions within the system.
Page 25: Advantages and Disadvantages of Airlift Reactors
Benefits include simple design and efficient mixing; challenges include greater air throughput needs.
Page 26: Membrane Reactors
Utilization of membranes for separating cells/enzyme streams in continuous systems.
Page 27: Challenges in Membrane Reactors
Potential distribution issues in reactions.
Page 28: Perfusion Bioreactor
Continuous medium exchange maintains optimal cell conditions.
Page 30: Photobioreactor
Controlled environment for biomass production via photosynthesis.
Page 32: Single Use Bioreactors
Characteristics and implications for use in production.
Page 34: Kinetics of Cell Growth in Batch Culture - Monod Model
Assumptions and expressions related to growth dynamics.
Page 38: Significance of Monod Model
Analysis of kinetic behavior under varying substrate conditions.
Page 40: Performance Equation of a Batch Reactor
Focus on batch reactor material balance equations.
Page 41: Yield Coefficient of Batch Reactor
Explains biomass and substrate balance dynamics.
Page 50: Problem Solving Example - Batch Fermentation
Calculation of growth parameters based on data.
Page 51: Performance Equation of a Fed-Batch Reactor
Describes structure and operational focus of fed-batch processes.
Page 54: Substrate Balance Dynamics
Key equations relating to substrate consumption and production.
Page 56: Fed-Batch Applications in Industrial Processes
Example of penicillin production and parameters involved.
Page 57-62: Continuous Culture Dynamics
Emphasizes steady-state conditions and material balance principles in chemostats.
Page 63-66: Chemostat Models and Performance Equations
Detailed examination of biomass productivity and substrate utilization models.