Chemical Engineering - Environmental Engineering

31. 

The main pollutant in waste water discharged from a petroleum refinery is oil (both in free and emulsified form). Free oil is removed by

A. biological oxygen pond.
B. aerated lagoons.
C. trickling filters.
D. gravity separator having oil skimming devices.

Answer: Option D

Explanation:

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32. 

Phenolic water generated in coke ovens & by-product plant attached to an integrated steel plant containing phenol in concentration of less than 100 mg/litre can be removed by

A. chlorination
B. treating in biological oxygen pond
C. chemical coagulation
D. none of these

Answer: Option B

Explanation:

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33. 

Which of the following dust collection equipments is the least efficient (for sub-micronic particles) ?

A. Dust catcher (gravity type)
B. Cyclone separator
C. Bag filter
D. Hollow wet scrubber

Answer: Option A

Explanation:

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34. 

Bag filter design is predominantly dependent on gas temperature, as it affects the gas density & viscosity and the selection of filtering material. The pressure drop in a bag filter is

A. inversely proportional to viscosity of gas.
B. proportional to the viscosity & density of the gas.
C. proportional to the pressure of the gas.
D. both (b) and (c).

Answer: Option D

Explanation:

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35. 

Dust collection efficiency of a cyclone separator depends upon its

A. diameter.
B. inlet gas velocity.
C. overall height.
D. all (a), (b) & (c).

Answer: Option D

Explanation:

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