Iron, Manganese & Hydrogen Sulfide Removal Flashcards
7 cards from real CWS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Iron, Manganese & Hydrogen Sulfide Removal flashcards as text
When iron bacteria are confirmed in a water supply, which treatment approach is most appropriate?
Answer: Chlorine injection followed by contact time and filtration
Iron bacteria require disinfection with chlorine (or another oxidant) to destroy the organisms before filtration removes the resulting solids.
Potassium permanganate (KMnO4) is used in water treatment primarily to:
Answer: Oxidize iron, manganese, and hydrogen sulfide
Potassium permanganate is a strong oxidizer that converts dissolved iron, manganese, and hydrogen sulfide into filterable precipitates.
To avoid pink or purple staining of fixtures, how should potassium permanganate dosing be controlled?
Answer: Achieve complete oxidation with no excess residual
Excess potassium permanganate residual in treated water will stain fixtures pink or purple, so dosing must not exceed what is consumed during oxidation.
Birm filtration media removes iron and manganese primarily through which mechanism?
Answer: Catalytic oxidation
Birm uses dissolved oxygen already present in the water as a catalytic oxidizer to convert dissolved metals into filterable particles.
A customer reports persistent black staining on fixtures and darkened laundry. Which contaminant is the most likely cause?
Answer: Elevated manganese levels
Manganese oxidizes to form black or brownish-black precipitates that stain fixtures, laundry, and plumbing components.
For aeration to effectively oxidize iron, the dissolved oxygen (DO) level in the water should be:
Answer: Above 2 mg/L to support oxidation
Adequate dissolved oxygen (above approximately 2 mg/L) is required to drive the oxidation of ferrous iron to ferric iron.
Which type of iron filter requires periodic regeneration with a potassium permanganate solution to restore oxidizing capacity?
Answer: Greensand filter
Greensand media is coated with manganese dioxide, which is depleted over time and must be restored through backwashing and regeneration with potassium permanganate.