Скачать или смотреть GATE 2025 Civil | Set 1 | Q.32 | Aeration in Water Treatmen |GATE 202 |Which Pollutants Are Removed?

Question (GATE – Environmental Engineering):
Aeration is used as a treatment method for removing several pollutants from contaminated water.
Identify the pollutants for which aeration plays a role in their removal:

(A) Iron
(B) Cadmium
(C) Manganese
(D) Zinc

Correct Answer: Iron and Manganese
Concept:
Aeration is used in water treatment to oxidize certain dissolved metals so they can precipitate and be removed by filtration.

Metals that are removed using aeration:
1. Iron (Fe²⁺ → Fe³⁺ → Fe(OH)₃↓)

Aeration oxidizes soluble ferrous iron into ferric hydroxide precipitate, which can be filtered.

2. Manganese (Mn²⁺ → Mn⁴⁺ → MnO₂↓)

Aeration helps oxidize manganese into manganese dioxide precipitate.
Metals NOT removed by aeration:

Cadmium → requires chemical precipitation, adsorption, or ion exchange.

Zinc → typically removed through chemical precipitation (as hydroxide), not aeration.

Aeration
Water treatment
Iron removal
Manganese removal
Environmental engineering
GATE 2025
Water purification
Oxidation in water treatment
Civil Engineering
Environmental science MCQ

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