GATE Biotechnology Bioprocess Engineering and Process Biotechnology Syllabus

Bioprocess Engineering and Process Biotechnology syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Bioprocess Engineering and Process Biotechnology in GATE Biotechnology, not a summary of it.

1. 1

   Bioreaction Engineering

   9 topics

   • Rate law, zero and first order kinetics
   • Ideal reactors
     • Batch flow
     • Mixed flow
     • Plug flow
   • Enzyme immobilization
   • Diffusion effects
     • Thiele modulus
     • effectiveness factor
     • Damkoehler number
   • Kinetics of cell growth, substrate utilization and product formation
   • Structured and unstructured models
   • Batch, fed-batch and continuous processes
   • Microbial and enzyme reactors
   • Optimization and scale up
2. 2

   Upstream and Downstream Processing

   7 topics

   • Media formulation and optimization
   • Sterilization of air and media
   • Filtration
     • Membrane filtration
     • Ultra filtration
   • Centrifugation - high speed and ultra
   • Cell disruption
   • Principles of chromatography
     • Ion Exchange
     • Gel Filtration
     • GC
     • FC
     • FPLC
   • Extraction, adsorption and drying
3. 3

   Instrumentation and Process Control

   5 topics

   • Pressure, temperature and flow measurement devices
   • Valves
   • First order and second order systems
   • Feedback and feed forward control
   • Types of controllers
     • proportional
     • derivative and integral control
     • tuning of controllers

Bioprocess Engineering and Process Biotechnology flashcards for GATE Biotechnology

23 of 50 cards from the Bioprocess Engineering and Process Biotechnology deck — real questions with worked answers.

1. State the general rate law for a reaction in terms of reactant concentration and order $n$.

   $$-r_A = k\,C_A^{\,n}$$ where $-r_A$ is the rate of consumption of $A$, $k$ is the rate constant, $C_A$ the concentration, and $n$ the reaction order.

2. Write the integrated rate equation and the concentration-vs-time profile for a zero-order reaction.

   $$C_A = C_{A0} - k t$$ Concentration falls linearly with time; the rate $-r_A = k$ is independent of $C_A$. Units of $k$: $\text{mol·L}^{-1}\text{·s}^{-1}$.

3. Write the integrated rate equation for a first-order reaction and give the units of $k$.

   $$\ln\frac{C_{A0}}{C_A} = k t \quad\Rightarrow\quad C_A = C_{A0}\,e^{-kt}$$ The rate constant $k$ has units of $\text{s}^{-1}$ (time$^{-1}$).

4. Give the half-life expressions for zero-order and first-order reactions.

   Zero order: $t_{1/2} = \dfrac{C_{A0}}{2k}$ (depends on initial concentration). First order: $t_{1/2} = \dfrac{\ln 2}{k} = \dfrac{0.693}{k}$ (independent of concentration).

5. What are the three ideal reactor types studied in bioprocess engineering?

   The batch reactor (BR), the mixed-flow / continuous stirred-tank reactor (CSTR), and the plug-flow reactor (PFR).

6. Define an ideal batch reactor and write its design (mole-balance) equation.

   A closed vessel with no inflow or outflow, perfectly mixed so composition is uniform but changes with time. Design equation: $$t = C_{A0}\int_{X=0}^{X}\frac{dX}{-r_A} = -\int_{C_{A0}}^{C_A}\frac{dC_A}{-r_A}$$

7. Define an ideal mixed-flow reactor (CSTR) and write its design equation.

   A continuously fed, perfectly mixed open vessel where outlet composition equals the contents (uniform). Design equation: $$\tau = \frac{V}{Q} = \frac{C_{A0}X}{-r_A} = \frac{C_{A0}-C_A}{-r_A}$$

8. Define an ideal plug-flow reactor (PFR) and write its design equation.

   A continuous tubular reactor in which fluid moves as discrete plugs with no axial mixing; composition varies along the length. Design equation: $$\tau = \frac{V}{Q} = C_{A0}\int_0^X\frac{dX}{-r_A}$$

9. For a first-order reaction at a given conversion, which requires a larger volume — a CSTR or a PFR — and why?

   The CSTR requires a larger volume. A CSTR operates entirely at the low outlet rate (low $C_A$), whereas the PFR experiences a gradient of higher rates along its length, so the PFR is more volume-efficient (a PFR behaves like an infinite series of CSTRs).

10. Define space time $\tau$ and dilution rate $D$ for a continuous reactor.

    Space time $\tau = \dfrac{V}{Q}$ is the mean residence time. Dilution rate $D = \dfrac{Q}{V} = \dfrac{1}{\tau}$ is the number of reactor volumes passing per unit time (units $\text{h}^{-1}$).

11. What is enzyme immobilization and name its four main methods.

    Attaching/confining an enzyme to a solid support or matrix so it can be retained and reused. Methods: (1) adsorption, (2) covalent binding, (3) entrapment (in gels/fibers), and (4) encapsulation/cross-linking (e.g., CLEAs).

12. List two advantages and one disadvantage of enzyme immobilization.

    Advantages: enzyme reuse/continuous operation and easier product separation; often improved thermal/operational stability. Disadvantage: introduction of mass-transfer (diffusion) limitations that can lower the apparent (effective) reaction rate.

13. Distinguish external and internal diffusion limitations in immobilized enzyme systems.

    External (film) diffusion: substrate transport across the stagnant liquid boundary layer to the particle surface. Internal (pore) diffusion: substrate transport within the porous support to active sites inside the particle. Both reduce the observed rate below intrinsic kinetics.

14. Define the Thiele modulus $\phi$ and state what it physically compares.

    $$\phi = L\sqrt{\frac{k}{D_e}}$$ (first-order, slab of half-thickness $L$). It compares the intrinsic reaction rate to the internal diffusion rate. Large $\phi$ = diffusion-limited; small $\phi$ = reaction-limited.

15. Define the effectiveness factor $\eta$ for an immobilized biocatalyst.

    $$\eta = \frac{\text{actual (observed) reaction rate}}{\text{rate with no internal diffusion limitation}}$$ It ranges $0 < \eta \leq 1$; $\eta \to 1$ when diffusion is fast, $\eta \ll 1$ when diffusion-limited.

16. How does the effectiveness factor relate to the Thiele modulus at large $\phi$ for a first-order reaction in a spherical/slab pellet?

    At large $\phi$, $\eta \approx \dfrac{1}{\phi}$ (slab) — the reaction becomes strongly diffusion-limited and $\eta$ falls inversely with $\phi$. For a sphere $\eta = \dfrac{1}{\phi}\left(\dfrac{1}{\tanh 3\phi}-\dfrac{1}{3\phi}\right)$.

17. Define the Damköhler number used in external-diffusion analysis of immobilized enzymes.

    $$Da = \frac{\text{maximum reaction rate}}{\text{maximum mass-transfer rate}} = \frac{V_{max}}{k_L a\,C_{Ab}}$$ $Da \ll 1$: reaction-limited; $Da \gg 1$: diffusion (mass-transfer)-limited.

18. Write the Monod equation describing specific cell growth rate.

    $$\mu = \mu_{max}\frac{S}{K_S + S}$$ where $\mu$ is the specific growth rate, $\mu_{max}$ the maximum, $S$ the limiting substrate concentration, and $K_S$ the saturation (half-velocity) constant.

19. What does $K_S$ represent in the Monod equation?

    $K_S$ is the substrate concentration at which the specific growth rate equals half its maximum, i.e., $\mu = \tfrac{1}{2}\mu_{max}$. A low $K_S$ indicates high affinity for the substrate.

20. Write the equation for exponential (balanced) growth of biomass and define the doubling time.

    $$\frac{dX}{dt} = \mu X \;\Rightarrow\; X = X_0 e^{\mu t}$$ Doubling time: $t_d = \dfrac{\ln 2}{\mu} = \dfrac{0.693}{\mu}$.

21. Name the phases of microbial growth in a batch culture in order.

    Lag phase, exponential (log) phase, deceleration phase, stationary phase, and death (decline) phase.

22. Define the biomass yield coefficient $Y_{X/S}$ and product yield $Y_{P/S}$.

    $Y_{X/S} = -\dfrac{dX}{dS} = \dfrac{\text{mass of cells produced}}{\text{mass of substrate consumed}}$; $Y_{P/S} = -\dfrac{dP}{dS} = \dfrac{\text{mass of product formed}}{\text{mass of substrate consumed}}$.

23. Write the substrate-utilization equation including growth and maintenance terms.

    $$-\frac{dS}{dt} = \frac{1}{Y_{X/S}}\frac{dX}{dt} + \frac{1}{Y_{P/S}}\frac{dP}{dt} + m X$$ where $m$ is the maintenance coefficient (substrate used for cell upkeep, not growth).

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