250+ TOP MCQs on Wastewater and Treatment Processes and Answers

Microbiology Multiple Choice Questions on “Wastewater and Treatment Processes”.

1. Which of the following sewerage systems carry domestic and industrial wastewater?
A. sanitary sewers
B. storm sewers
C. combined sewers
D. storm and combined sewers
Answer: A
Clarification: Sanitary sewers carry domestic and industrial wastewater for its ultimate treatment and disposal.

2. The more oxidizable organic material, the lesser the BOD.
A. True
B. False
Answer: B
Clarification: The magnitude of the BOD is related to the amount of organic material in the wastewater-i.e., the more oxidizable organic material, the higher the BOD.

3. Which of the following is a strict anaerobe?
A. Enterobacter
B. Alcaligenes
C. Pseudomonas
D. Methanosarcina
Answer: D
Clarification: Methane producers are strict anaerobes e.g., Methanobacterium, Methanosarcina, Methanococcus. They produce methane and carbon dioxide as end products.

4. In which of the following treatment involve oxidation of organic constituents of the wastewater?
A. Primary treatment
B. Secondary treatment
C. Advanced treatment
D. Final treatment
Answer: B
Clarification: Secondary or biological treatment is done to adsorb and ultimately oxidize organic constituents of the wastewater, i.e, to reduce the BOD.

5. The upper region of the trickling filter is favorable for the growth of _____________
A. fungi
B. protozoa
C. algae
D. bacteria
Answer: C
Clarification: The upper region of the trickling filter is favorable for the growth of algae, and at times their growth may become so extensive that it impairs the operation of the filter.

6. Activated sludge usually employs an aeration period of ________________
A. 1 hour
B. 24 hours
C. 10-15 hours
D. 4-8 hours
Answer: D
Clarification: The activated sludge process usually employs an aeration period of 4 to 8 hours, after which the mixture is piped to a sedimentation tank.

7. Oxidation ponds are very deep ponds.
A. True
B. False
Answer: B
Clarification: Oxidation ponds also called lagoons are shallow ponds which are 2 to 4 ft in depth designed to allow algal growth on the wastewater effluent.

8. Trickling filter is used in which of the following wastewater treatment processes?
A. Primary treatment
B. Secondary treatment
C. Advanced treatment
D. Final treatment
Answer: B
Clarification: The trickling filter is used in secondary treatment in which a stationary microbial culture is fed by a continuous supply of nutrients. It is used for filtration processes.

9. Belt filter presses are used in which of the following process?
A. Thickening
B. Stabilization
C. Dewatering
D. Disposal
Answer: C
Clarification: Dewatering is done by vacuum filters, belt filter presses and centrifuges and is often enhanced by the addition of polymer or other chemical coagulant aids.

10. Which of the following gases are produced in large amounts during sludge digestion?
A. methane
B. carbon-dioxide
C. hydrogen
D. nitrogen
Answer: A
Clarification: About 60-70% methane is produced during sludge digestion with smaller amounts of carbon dioxide, hydrogen and nitrogen.

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