1. In which of the following bioreactors is the vessel divided into two interconnected zones?
a) Bubble column bioreactors
b) Airlift bioreactors
c) Continuous stirred tank bioreactors
d) Packed bed bioreactors
Explanation: In the airlift bioreactors, the medium of the vessel is divided into two interconnected zones by means of a baffle or draft tube. Air is pumped in one of two zones. The other zone that receives no gas is the down comer
2. Which of the following reactors is comparable to bubble column bioreactor?
a) Fluidized bed bioreactor
b) Packed bed bioreactors
c) Airlift bioreactors
d) Continuous stirred tank bioreactors
Explanation: Fluidized bed bioreactor is comparable to bubble column bioreactor except the top position is expanded to reduce the velocity of the fluid. The design of the fluidized bioreactors is such that the solids are retained in the reactor while the liquid flows out.
3. Which of the following bioreactor consists of biocatalysts on or within the matrix of solids?
a) Photo-bioreactors
b) Packed bed bioreactors
c) Airlift bioreactors
d) Fluidized bed bioreactor
Explanation: A bed of solid particles, with biocatalysts on or within the matrix of solids, packed in a column constitutes a packed bed bioreactor. The solids used may be porous or non-porous gels, and they may be compressible or rigid in nature.
4. Which bioreactor is designed for fermentation?
a) Photo bioreactors
b) Continuous stirred tank bioreactors
c) Fluidized bed bioreactor
d) Airlift bioreactors
Explanation: The bioreactors designed for fermentation that can be carried out either by exposing to artificial illumination or sunlight is called Photo bioreactors.
5. The array of tubes or flat panels constitutes ________ in photo bioreactors.
a) Light receiving systems
b) Heating systems
c) Cooling systems
d) Radiation emitting systems
Explanation: Glass or more commonly transparent plastic is used to make photo bioreactors. The array of tubes or flat panels constitutes light receiving systems (solar receivers).
6. Hydrolysis of chlorine in water has a rate constant of 11 s-1. What does this imply?
a) It is a slow reaction.
b) It is a moderate reaction
c) It is a fast reaction
d) It is a very slow reaction
Explanation: Hydrolysis of chlorine in water is a first order reaction. Any first order reactions with rate constant > 1s-1 is considered as a fast reaction. Hence the above reaction is a fast reaction.
7. Which type of reactor is used for mixing chemicals in water treatment?
a) Continuous reactor
b) Batch reactor
c) Plug flow reactor
d) Fixed bed reactor
Explanation: Batch reactors are used while mixing chemicals for water treatment. When chemicals such as alum, ferric ammonium sulphate are required for coagulation, chemical mixing is done. For the preparation of flocculants and other pH controlling chemicals also the same batch reactor process is used for chemical mixing.
8. In which type of reactor, mixing is uniform?
a) Ideal reactor
b) Batch reactor
c) Non-ideal reactor
d) Fixed bed reactor
Explanation: Ideal reactors are those in which the mixing is uniform. The reactors in which the mixing is not uniform, those reactors are known as non-ideal reactors. Ideal reactors have uniform hydraulic conditions.
9. Which type of reactor is not used for oxidation?
a) Packed bed reactor
b) Stirred tanks
c) Tank in series
d) Venturi reactor
Explanation: Packed bed reactors are not used for the oxidation reaction. Oxidation is carried out in a venturi reactor, tank in series and stirred tank reactors. Oxidation of Iron, Oxidation of manganese, dechlorination of SO2 and ozone reactions are carried out in these reactors.
10. Which type of reactor is not subjected to back mixing?
a) Plug flow
b) Completely stirred reactor
c) Batch reactors
d) Venturi reactor
Explanation: Plug flow reactors are not subjected to back mixing. They are designed for a specific detention time. Disinfection of water is carried out in a plug flow reactor.