CWS Iron, Manganese & Hydrogen Sulfide Removal 2

Question 1

When iron bacteria are confirmed in a water supply, which treatment approach is most appropriate?

Accepted Answer

Chlorine injection followed by contact time and filtration

Answer

Aeration alone followed by greensand filtration

Answer

Water softener regeneration with salt

Answer

Reverse osmosis as the sole treatment

Question 2

Potassium permanganate (KMnO4) is used in water treatment primarily to:

Accepted Answer

Oxidize iron, manganese, and hydrogen sulfide

Answer

Soften water by removing calcium ions

Answer

Lower water pH to acceptable levels

Answer

Add beneficial trace minerals to drinking water

Question 3

To avoid pink or purple staining of fixtures, how should potassium permanganate dosing be controlled?

Accepted Answer

Achieve complete oxidation with no excess residual

Answer

Maintain a slight pink residual in the water

Answer

Dose as much as possible for maximum effectiveness

Answer

Use only pre-dosed cartridge media with no liquid feed

Question 4

Birm filtration media removes iron and manganese primarily through which mechanism?

Accepted Answer

Catalytic oxidation

Answer

Ion exchange

Answer

Adsorption onto carbon

Answer

Biological filtration

Question 5

A customer reports persistent black staining on fixtures and darkened laundry. Which contaminant is the most likely cause?

Accepted Answer

Elevated manganese levels

Answer

High iron levels above 1.0 mg/L

Answer

High chlorine residual in the water

Answer

Hydrogen sulfide gas

Question 6

For aeration to effectively oxidize iron, the dissolved oxygen (DO) level in the water should be:

Accepted Answer

Above 2 mg/L to support oxidation

Answer

Below 1 mg/L to avoid over-oxidation

Answer

Exactly 0.5 mg/L for optimal reaction

Answer

Dissolved oxygen level has no effect on iron oxidation

Question 7

Which type of iron filter requires periodic regeneration with a potassium permanganate solution to restore oxidizing capacity?

Accepted Answer

Greensand filter

Answer

Birm filter

Answer

Activated carbon filter

Answer

Sediment cartridge filter