Iron, Manganese & Hydrogen Sulfide Removal Flashcards

What is the EPA secondary maximum contaminant level (SMCL) for iron in drinking water?

Answer: 0.3 mg/L

The EPA secondary MCL for iron is 0.3 mg/L; above this level, iron causes staining and aesthetic issues.

Which odor is most characteristic of hydrogen sulfide gas in a water supply?

Answer: Rotten egg smell

Hydrogen sulfide (H2S) produces a distinctive rotten egg odor even at very low concentrations.

Which form of iron passes through a standard sediment filter without being captured?

Answer: Ferrous iron (dissolved)

Ferrous (dissolved) iron remains in solution and cannot be filtered until it is oxidized to ferric (particulate) form.

What is the EPA secondary maximum contaminant level (SMCL) for manganese in drinking water?

Answer: 0.05 mg/L

The EPA SMCL for manganese is 0.05 mg/L; exceeding this causes black staining and undesirable taste.

Which oxidation method is most commonly used to convert dissolved ferrous iron to filterable ferric iron?

Answer: Aeration

Aeration exposes water to oxygen, converting soluble ferrous iron into insoluble ferric iron that can then be filtered.

Greensand filtration media is primarily used to remove which group of contaminants from water?

Answer: Iron, manganese, and hydrogen sulfide

Greensand (glauconite coated with manganese dioxide) acts as a catalytic oxidizer and filter for iron, manganese, and hydrogen sulfide.

What pH range is most favorable for effective oxidation and removal of dissolved iron from water?

Answer: pH 7.0–8.5

Iron oxidizes and precipitates most efficiently at neutral to slightly alkaline pH (7.0–8.5); low pH keeps iron in solution.