This set of Waste Water Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Moving Bed Reactor”.
1. _______ flows along with the reactants in MBR.
a) Pollutants
b) Microbes
c) Disinfectants
d) Catalytic materials
View Answer
Explanation: The catalytic material flows along with the reactants and is then separated from the exit stream and recycled in moving bed bioreactors.
2. Moving bed reactors are closed systems.
a) True
b) False
View Answer
Explanation: Moving bed reactors are catalytic reactors in which the catalyst moves through the reactor along with the reactants. They are open systems and operate at steady state.
3. Reactants enter from the bottom in MBR.
a) True
b) False
View Answer
Explanation: Reactants and catalyst enter the top of the reactor and move through the vessel. Once at the bottom the catalyst is removed and regenerated, products are removed from the reaction system and the catalyst is regenerated and brought to the top of the reactor.
4. Which of the following is an advantage of MBR?
a) Heat transfer
b) Fluid reactant
c) Solid distribution
d) Selectivity
View Answer
Explanation: In moving bed bioreactors catalyst is easy to regenerate, the handling cost of a catalyst is low and has plug flow characteristics with good selectivity.
5. Which of the following is a disadvantage of MBR?
a) Catalyst regeneration
b) Flow characteristics
c) Catalyst cost
d) Heat transfer
View Answer
Explanation: In moving bed reactor, the flow of solids is not easy to maintain and solid distribution is also difficult. It consists of poor heat transfer characteristics. The fluid reactant may bypass catalyst bed.
6. What is the load considered for biox media?
a) 1.8 kg/ m3
b) 2.6 kg/ m3
c) 6 kg/m3
d) 3.6 kg/m3
View Answer
Explanation: The load considered for biox media is 1.8 kg/ m3. These media are immersed in aeration tank. This increases the degradation of BOD.
7. Calculate the volume of the tank for the following information.
BOD: 400 mg/L
Flow: 3500 m3/h
Loading rate of media: 3.5 Kg/ m3/day
a) 9600 m3
b) 9000 m3
c) 2000 m3
d) 4000 m3
View Answer
Explanation: BOD load= BOD X flow rate. Volume of tank = BOD load/ loading rate of media. Volume of tank= {(400 X 3500 x24)/1000}/3.5=9600 m3.
8. What is the depth of biox media generally considered for an aeration tank?
a) 1.2 m
b) 3 m
c) 5 m
d) 2.5 m
View Answer
Explanation: The depth for bioxmedia is considered generally as 1.2 m. The total liquid depth for a tank is depth of biox media + liquid depth above biox media + liquid depth below biox media. The bio media increases the efficiency to degrade BOD.
9. What is the efficiency in reducing the BOD of a tank consisting f Biox media
a) 90%
b) 80%
c) 85%
d) 95%
View Answer
Explanation: The efficiency in reducing the BOD of a tank consisting of Biox media is 90 %. In normal activated sludge process this is around 70%. These media also reduce SRT of the tank when compared to the conventional Activated sludge process.
10. Calculate the area required for the system consisting of biox media for the following data.
Flow: 500 m3/h.
BOD: 500 mg/L
a) 8 m3
b) 3.4 m3
c) 3 m3
d) 4.4 m3
View Answer
Explanation: BOD load= BOD X flow rate. Volume of tank = BOD load/ loading rate of media. Volume of tank= {(500 X 500 x24)/1000000}/1.8=3.4 m3.
Sanfoundry Global Education & Learning Series – Waste Water Engineering.
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