1. Flocculation is a process ____.
[A] that removes algae from stabilization pond effluent
[B] that mixes the coagulant in water
[C] that promotes to aggregation of small particles into larger particles to enhance their removal by gravity
[D] None of these
Answer: Option C
2. Standard 5 day BOD of a waster water sample is nearly x% of the ultimate BOD, where x is
[A] 98
[B] 58
[C] 68
[D] 78
Answer: Option C
3. During temperature inversion in atmosphere, air pollutants tend to _____.
[A] disperse laterally
[B] accumulate above inversion layer
[C] disperse vertically
[D] accumulate below inversion layer
Answer: Option D
4. The design overflow rate of a sedimentation tank is chosen considering ______.
[A] Volume of the sedimentation tank
[B] Detention time in the tank
[C] Flow rate through the tank
[D] Diameter of the particle intended to be removed
Answer: Option D
5. The following zones formed in a polluted river:
- Zone of clear water
- Zone of active decomposition
- Zone of recovery
- Zone of degradation the correct sequence in which these zones occur progressively downstream in a polluted river is
[A] 2, 4, 3, 1
[B] 2, 4, 1, 3
[C] 4, 2, 3, 1
[D] 4, 2, 1, 3
Answer: Option C
Explanation: The correct sequence in which these zones occur progressively downstream in a polluted river is:
- Zone of degradation
- Zone of active decomposition
- Zone of recovery
- Zone of clear water