Downstream Processing

Question 1

Concentration polarization can be reduced
further by

a. pre filtering the solution
b. reducing the flow rate per unit membrane
surface area
c. back washing periodically
d. all of the above

Answer 1

d. all of the above

Question 2

A system which requires less solvent and
produces a more concentrated extract phase, is desired with a

a. large distribution coefficients
b. small distribution coefficients
c. very small distribution coefficients
d. constant distribution coefficients

Answer 2

a. large distribution coefficients

see PHB Ch.14

Question 3

The efficiency of cell disruption in a bead mill
depends on the

a. concentration of the cells
b. amount and size of beads
c. type and rotational speed of agitation
d. all of these

Answer 3

d. all of these

Question 4

A common filter medium is the cloth filter
generally made of

a. Canvas
b. synthetic fabrics
c. metal or glass fiber
d. all of these

Answer 4

d. all of these

Question 5

An ion exchange resin is composed of

a. polymeric network
b. ionic functional groups
c. counter ions
d. all of these

Answer 5

d. all of these

Question 6

Maintenance cost varies from
a. 0-4% of the capital cost
b. 12-16% of the capital cost
c. 4-8% of the capital cost
d. 8-12% of the capital cost

Answer 6

c. 4-8% of the capital cost

Question 7

The optimum wet solid content for the cell
suspension for a bead mill is typically somewhere between

a. 5-15% by volume
b. 15-30% by volume
c. 30-60% by volume
d. 60-90% by volume

Answer 7

c. 30-60% by volume

Question 8

Assuming the laminar flow across the filter, the rate of filtration (dVf/dt) can be expressed as a function of pressure drop Dp by the modified D’Arcy’s equation as (where A is the area of filtering surface, K is the D’Arcy’s filter cake permeability and Lis the thickness of the filter cake)

a. (1/A) dVf/dt = Δp/μ(L/K)
b. dVf/dt = (1/A)Δp/μ(L/K)
c. (1/A) dVf/dt = Δp/μ LK
d. dVf/dt = (1/A)Δp/μ LK

Answer 8

a. (1/A) dVf/dt = Δp/μ(L/K)

Question 9

Filtration leaf test results indicate that the
filtration rate of a protein product is 100 dry
lbs/(ft2 hr). What size production filter would be required to obtain 100 dry lbs of filter cake/hr?

a. 1.54 ft^2
b. 3.08 ft^2
c. 65 ft^2
d. 65 lbs/ ft^2.hr

Answer 9

a. 1.54 ft^2

Question 10

Selectivity can be expressed as

a. ratio of the distribution coefficients in
different solute

b. mass fraction of the solute in the extract
phase at equilibrium

c. mass fraction of the solute in the raffinate
phase

d. ratio of the mass fraction of the solute in the extract phase to the raffinate phase

Answer 10

a. ratio of the distribution coefficients in different solute

See PHB Ch. 14

Question 11

The disk centrifuge is the type of centrifuge
used most often for bio separations due to its

a. continuous operation
b. lesser cost
c. higher speed
d. ease in operation

Answer 11

b. lesser cost

Question 12

The stage wise operation of adsorption is called
a. contact filtration
b. conventional adsorption
c. affinity adsorption
d. ion exchange

Answer 12

a. contact filtration

Question 13

Which of the following is not the physical
method for the cells rupturing?
a. Milling
b. Homogenization
c. Ultrasonication
d. Enzymatic digestion

Answer 13

d. Enzymatic digestion

Question 14

Conventional adsorption is a

a. reversible process
b. irreversible process
c. either reversible or irreversible
d. none of these

Answer 14

a. reversible process

Question 15

If the solute passes through membrane freely,
the the rejection coefficient (s) is

a. 1
b. 0
c. >1
d. <1

Answer 15

c. >1

Question 16

If the membrane rejects all solute, the rejection coefficient (s) is
a. 1
b. 0
c. >1
d. <1

Answer 16

a. 1

Question 17

In antibiotic manufacturing processes, the
fermentation time ranges from

a. 2-3 weeks
b. 1-2 weeks
c. 4-5 weeks
d. 2-4 weeks

Answer 17

c. 4-5 weeks

Question 18

The conventional filtration involves the
separation of large particles generally

a. dp>5μm
b. dp>10μm
c. dp>15μm
d. dp>20μm

Answer 18

b. dp>10μm

Question 19

Which of the operation does not come under
upstream processing?
a. Media preparation
b. Inoculum development
c. Effluent treatment
d. Storage of raw material

Answer 19

c. Effluent treatment

Question 20

For cost analysis in a fermenter system, the
depreciation cost varies from

a. 5-6% of the capital cost
b. 6-7% of the capital cost
c. 6-10% of the capital cost
d. 8-10% of the capital cost

Answer 20

c. 6-10% of the capital cost

Question 21

Micro filtration refers to the separation of
suspended material such as bacteria by using a membrane with spore sizes of

a. 0.02 to 10μm
b. 1-10A°
c. 20-30μm
d. 10-200A°

Answer 21

a. 0.02 to 10μm

Question 22

Start up expenses in a fermentation industry
varies from

a. 0-5% of the capital cost
b. 10-15% of the capital cost
c. 5-10% of the capital cost
d. 15-20% of the capital cost

Answer 22

c. 5-10% of the capital cost

Question 23

The solvent flux across the membrane can be
expressed as (where A is the area, Lp is the
membrane permeability, σ is the reflection
point, Δp is applied pressure and Δπ is the
osmotic pressure)

a. J = Lp(Δp - σΔπ)
b. J/A = Lp(Δp - σΔπ)
c. J= Lp/σΔπ
d. J/A = Lp/Δp

Answer 23

a. J = Lp(Δp - σΔπ)

Question 24

Which of the following is considered as a
pretreatment to the biological feeds?

a. Heating to denature the proteins
b. Addition of filter aids to increase the porosity
c. Addition of electrolytes
d. All of the above

Answer 24

d. All of the above

Question 25

For the extractions operation, the selectivity should be a. > 1 b. < 1 c. 1 d. Zero

Answer 25

a. > 1

Question 26

The purity of a solute collected between two times t1 and t2 during chromatographic separation can be calculated as a. amount of solute eluted - amount of impurity eluted b. amount of solute eluted / amount of impurity eluted c. amount of solvent eluted + amount of impurity eluted d. amount of solvent eluted / amount of impurity eluted

Answer 26

b. amount of solute eluted / amount of impurity eluted

Question 27

Chromatography is based on the a. different rate of movement of the solute in the column b. separation of one solute from other constituents by being captured on the adsorbent c. different rate of movement of the solvent in the column d. any of the above

Answer 27

a. different rate of movement of the solute in the column

Question 28

The correlation often employed to correlate adsorption data for protein is (where Ymax is the maximum amount of solute adsorbed per mass of adsorbent, X is the mass fraction of solute in the diluent phase in solute-free basis, KL is a constant and Y is the equilibrium value of the mass of solute adsorbed per mass of adsorbent) a. Y = YmaxX/(KL+X) b. Y= Ymax/(KL+X) c. Y= YmaxX/KL d. Y = Ymax- X/ (KL+X)

Answer 28

a. Y = YmaxX/(KL+X)

Question 29

A typical tubular centrifuge has a bowl of 2 to 5 inch in diameter and 9 to 30 inch in height with a maximum rotating speed of a. 15,000 to 50,000 rpm b. 50,000 to 100,000 rpm c. 100,000 to 150,000 rpm d. 150,000 to 200,000 rpm

Answer 29

a. 15,000 to 50,000 rpm