Discussion
Home ‣ Biochemical Engineering ‣ Downstream Processing Comments
- Question
The optimum wet solid content for the cell suspension for a bead mill is typically somewhere between
Options- A. 5-15% by volume
- B. 15-30% by volume
- C. 30-60% by volume
- D. 60-90% by volume
- Correct Answer
- 30-60% by volume
- 1. Which of the following is not the physical method for the cells rupturing?
Options- A. Milling
- B. Homogenization
- C. Ultrasonication
- D. Enzymatic digestion Discuss
- 2. The disk centrifuge is the type of centrifuge used most often for bio separations due to its
Options- A. continuous operation
- B. lesser cost
- C. higher speed
- D. ease in operation Discuss
- 3. 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
Options- 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 Discuss
- 4. The solvent flux across the membrane can be expressed as (where A is the area, Lp is the membrane permeability, ? is the reflection point, ?p is applied pressure and ?? is the osmotic pressure)
Options- A. J = Lp(?p - ???)
- B. J/A = Lp(?p - ???)
- C. J = Lp/???
- D. J/A = Lp/?p Discuss
- 5. Concentration polarization can be reduced further by
Options- A. pre filtering the solution
- B. reducing the flow rate per unit membrane surface area
- C. back washing periodically
- D. all of the above Discuss
- 6. The effectiveness of a solvent can be measured by the
Options- A. distribution coefficients
- B. selectivity
- C. both (a) and (b)
- D. diffusivity Discuss
- 7. A system which require less solvent and produces a more concentrated extract phase, is desired with a
Options- A. large distribution coefficients
- B. small distribution coefficients
- C. very small distribution coefficients
- D. constant distribution coefficients Discuss
- 8. If the membrane rejects all solute, the rejection coefficient (s) is
Options- A. 1
- B. 0
- C. >1
- D. <1 Discuss
- 9. 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 L is the thickness of the filter cake)
Options- A. (1/A) dVf/dt = ?p/?(L/K)
- B. dVf/dt = (1/A)?p/?(L/K)
- C. (1/A) dVf/dt = ?p/? LK
- D. dVf/dt = (1/A)?p/? LK Discuss
- 10. 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?
Options- A. 1.54 ft2
- B. 3.08 ft2
- C. 65 ft2
- D. 65 lbs/ ft2.hr Discuss
Downstream Processing problems
Search Results
Correct Answer: Enzymatic digestion
Correct Answer: lesser cost
Correct Answer: 15,000 to 50,000 rpm
Correct Answer: J = Lp(?p - ???)
Correct Answer: all of the above
Correct Answer: both (a) and (b)
Correct Answer: large distribution coefficients
Correct Answer: 1
Correct Answer: (1/A) dVf/dt = ?p/?(L/K)
Correct Answer: 1.54 ft2
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