This set of Bioprocess Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Practical Considerations For Bioreactor Construction”.
1. Positive pressure is the pressure in which air flows only inside.
a) True
b) False
View Answer
Explanation: In Positive pressure air or gas pressure is greater than that of the atmosphere. Air will flow out of the room instead of in, so that any airborne microorganisms (e.g., bacteria) does not contaminate the environment in the bioreactor.
2. The vessel of bioreactor is draining from _________
a) Top
b) Below
c) Bottom
d) Side
View Answer
Explanation: The vessel must be fully draining via a harvest nozzle located at the lowest point of the reactor.
3. The vessel should have the minimum number of internal structures.
a) True
b) False
View Answer
Explanation: Industrial fermenters are designed for in situ steam sterilisation under pressure. The vessel should have a minimum number of internal structures, ports, nozzles, connections and other attachments to ensure that steam reaches all parts of the equipment. For effective sterilisation, all air in the vessel and pipe connections must be displaced by steam.
4. Simple gate and globe valves are not better valves.
a) True
b) False
View Answer
Explanation: Common designs such as simple gate and globe valves have a tendency to leak around the valve stem and accumulate broth solids in the closing mechanism. Although used in the fermentation industry, they are unsuitable if a high level of sterility is required.
5. For smaller vessels, which type of sealing is required between the gap of fermenter and the stirrer?
a) Mechanical seal
b) Double-mechanical seal
c) Magnetic seal
d) Non-magnetic seal
View Answer
Explanation: On smaller vessels, magnetic drives can be used to couple the stirrer shaft with the motor; with these devices, the shaft does not pierce the fermenter body. A magnet in a housing on the outside of the fermenter is driven by the stirrer motor; inside, another magnet is attached to the end of the stirrer shaft and held in place by bearings. Sufficient power can be transmitted using magnetic drives to agitate vessels up to at least 800 litres in size.
6. Glass fermenters is used for about _____
a) 50 litres capacity
b) 100 litres capacity
c) 300 litres capacity
d) 30 litres capacity
View Answer
Explanation: Glass is used to construct fermenters up to about 30 litres capacity. The advantages of glass are that it is smooth, non-toxic, corrosion-proof and transparent for easy inspection of the vessel contents.
7. Copper is not suitable for the construction of the fermenters.
a) True
b) False
View Answer
Explanation: Copper and copper-containing materials must be avoided in all parts of the fermenter contacting the culture because of its toxic effect on cells.
8. Cheaper grades of stainless steel is not preferred in the construction of the fermenter.
a) True
b) False
View Answer
Explanation: Cheaper grades of stainless steel may be used for the jacket and other surfaces isolated from the broth.
9. Electro polishing is also referred as _________
a) Anodic polishing
b) Cathodic polishing
c) Electron polishing
d) Non-ionic polishing
View Answer
Explanation: Electropolishing, also known as electrochemical polishing, anodic polishing or electrolytic polishing (especially in the metallography field), is an electrochemical process that removes material from a metallic workpiece. It is used to polish, passivate, and deburr metal parts. It is often described as the reverse of electroplating.
10. Which sparger consist of a single open or partially-closed pipe providing a stream of air bubbles?
a) Perforated sparger
b) Orifice sparger
c) Nozzle sparger
d) Porous sparger
View Answer
Explanation: Nozzle spargers are used in many agitated fermenters from laboratory to production scale. These spargers consist of a single open or partially-closed pipe providing a stream of air bubbles.
11. Which of the following sparger is most suitable for agitated fermenters?
a) Perforated sparger
b) Orifice sparger
c) Nozzle sparger
d) Porous sparger
View Answer
Explanation: Nozzle spargers are used in many agitated fermenters from laboratory to production scale. These spargers consist of a single open or partially-closed pipe providing a stream of air bubbles; advantages compared with other sparger designs include low resistance to gas flow and small risk of blockage.
12. A water cooled condenser is a heat exchanger.
a) True
b) False
View Answer
Explanation: A water-cooled condenser is a heat exchanger that removes heat from refrigerant vapor and transfers it to the water running through it. Having the refrigerant vapor condensed on the outside of a tube does this. In doing so, the vapor condenses and gives up heat to the water running inside the tube.
13. Is bioreactor and fermentor same?
a) True
b) False
View Answer
Explanation: Bioreactor: A vessel that provides you the facility of carrying out a chemical process involving the organisms or biochemically active substances which are derived from such organisms is called a bioreactor. Fermentor: The device that is able to perform the process of fermentation is known as fermentor.
14. All bioreactors deal with ___________
a) Homogenous systems
b) Heterogeneous systems
c) Non-heterogeneous systems
d) Isolated systems
View Answer
Explanation: All bioreactors deal with heterogeneous systems dealing with two or more phases, e.g., liquid, gas, solid. Therefore, optimal conditions for fermentation necessitate efficient transfer of mass, heat and momentum from one phase to the other.
15. Anaerobic fermenters are complex than aerobic fermenters.
a) True
b) False
View Answer
Explanation: Industrial fermenters can be divided into two major classes, anaerobic and aerobic. Anaerobic fermenters require little special equipment except for removal of heat generated during the fermentation process, whereas aerobic fermenters require much more elaborate equipment to ensure that mixing and adequate aeration are achieved.
Sanfoundry Global Education & Learning Series – Bioprocess Engineering.
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