IB342 - BIOPROCESS ENGINEERING ANNAUNIVERSITY PREVIOUS YEAR QUESTION PAPER

MODEL QUESTION PAPER

VI - SEMESTER 

B.TECH. INDUSTRIAL BIO-TECHNOLOGY

IB342 - BIOPROCESS ENGINEERING

Time: 3hrs Max Marks: 100

The question paper has two parts. Part A and Part B. Part A has ten questions two marks each and Part B has five questions six marks each. Question No. 11 to 14 has one alternative to each question. Answering all questions is essential.

Answer all Questions
PART – A (10 x 2 = 20 Marks)

1.On scaling up, it is mathematically absurd to get identical conditions in all terms in the scaled up reactor compared to the base reactor. Give mathematical explanation for the above fact.
2.A bacteria is doubling in every thirty minutes, find out its specific growth rate assuming first order growth kinetics.
3.Prove that overall mass transfer resistance is approximately equal to the resistance at the stagnant liquid film side.
4.Derive Monod model from Konak model.
5.Why vortex formation in a reactor is to be stopped and how it can be stopped?
6.What are the differences in pulse input and step input, exemplify with required sketches of inputs and outputs for CSTR.
7.What do you understand by diauxic growth?
8.What are the advantages to have normalized residence time distribution function?
9.Under identical conditions which cell will grow at higher specific growth rate, a cell of 5µm diameter or a cell of 10 µm diameter and why?
10.Prove analytically that cell productivity in continuous reactor is more than that of batch reactor.

PART – B (15 x 16 = 80 Marks)

11. Derive an expression for the critical gas flow rate through a gas spurger in a liquid tank for the formation of constant size gas bubble, the frequency of which varies with the gas-flow rate. Assume Renolds number is less than 1.

(OR)

A large stirred tank fitted with flat blade turbine impeller 35000 1 liquid capacity is used for the growth of a fungal species for antibiotic production. Given the tank geometry, broth properties and air flow rate below, calculate the mass transfer coefficient kLa for both coalescing and non-coalescing system, and then comment on the result obtained in two cases that why they are not equal. Also calculate impeller speed assuming power number constant and has a value 6 for flat blade turbine impeller. The power supplied to the aerated tank is 2.38 x 104 Watt.

Air flow rate: 0.3 vvm
Tank height to diameter ratio (H/DT): 3
Impeller diameter to tank diameter ratio (DI/DT): 0.5
Liquid density (?L): 1.05 g cm-3


12. The concentration at the exit end against a pulse input in a reactor is presented in the following table for RTD analysis.

t, s 0 150 175 200 225 240 250 260
C, g l-1 0 0 1 3 7.4 9.4 9.7 9.4

t, s 275 300 325 350 375 400 450
C, g l-1 8.2 5.0 2.5 1.2 0.5 0.2 0

Plot E (t) (t-tm)2 as a function of time. What fraction of material spends time between 230 and 270 s in the reactor?

(OR)

A pulse test on a piece of reaction equipment gave the following results. The output concentration rose linearly from zero to 0.5µmol l-1 in five minutes and then fell linearly to zero in 10 min. Plot E and F curve. What was the mean residence time? If the flow were 150 mlmil-1, what would be the total reactor volume?


13. Design a bioreactor for certain organism in which two separate reactors to be used in series for two different substrates. Give steady state cell and substrate concentration from both the reactors.

(OR)

Derive the expression of specific growth rate for multiple substrate utilization. Specify what type of substrate inhibition it is?

14. The growth of a bacteria Stepinpoopi can be described by the logistic growth law:

with µm = 0.5 h-1 and = 20 g dm-3 and substrate is in excess quality. The cell growth is to be carried out 2 dm3 batch reactor. Plot the growth rate and cell concentration as function of time after inoculation of 0.4 g of cell into the reactor (ignore the lag period).

(OR)

The batch reactor in the above sum is to be turned into a CSTR. Derive an equation for the washout rate. Choose volumetric flow rate of the entering substrate and find the steady state cell and substrate concentration.y = 0.4, sn = 40 g/dm3


15.For an organism the cell growth rate is given by the following expression

Find an expression for product formation p(t) if the product is non growth associated.

For Viscous system

= 0.06 

= K (11N)n-1 

For coalescing system

kLa = 2.6 x 10-2 

For non-coalescing system

kLa = 2.0 x 10-3 

Dimensionless groups

Re = ; Fr = ; Sc = ; Power No. = 

Symbols used in the above formulae

KLa Mass transfer constant Apparent viscosity
N Impeller speed K Consistency index
V Volume of the reactor n Power law index
P Power input vs Superficial velocity
Concentration of the liquid Surface tension
D Diffusion constant

Symbols used elsewhere hold their usual meaning.