Greensand treated with Potassium Permanganate is used to remove ______ from water?

Iron and manganese

An iron bacteria that will oxidize iron in water and use the energy for reducing carbon dioxide to organic forms is a?

Crenothrix, Thiothrix

What is the best method to test for iron in the water?

Atomic Absorption (AA)

When testing for iron, if there is clay or visible rust you should not ______ the sample?

Acidify, Also, ask lab to analyze immediately

Polyphosphate should always be added to the water prior to?

Chlorine

Never use a polyphosphate over ______ old?

48 hours

A WTP using polyphosphate to control iron corrosion is getting calls because of red water in the distribution system. What is the likely cause of the red water?

Ans. Iron Bacteria
Ans. Polyphosphate reverted to orthophosphate

Soluble iron can be oxidized to insoluble precipitates by ______ and removed by sedimentation & filtration?

Ans. Chlorine
Ans. Aeration
Ans. Potassium Permanganate

When using aeration to oxidize Iron from the water, increasing the ______ will improve the removal efficiency?

pH

What chemical is commonly used to dechlorinate large amounts of water?

Sodium Bisulfite

Potassium Permanganate is used with ______ to remove iron and manganese from water.

Greensand Filtration

What is used to regenerate a manganese greensand filter?

Permanganate (KMnO₄)

What causes pink water?

Overdose of KMnO₄

A WTP with greensand treatment is receiving red water complaints from its customers. What is the likely cause?

Ans. Iron Bacteria
Ans. Greensand needs to be regenerated with KMnO₄

Electromedia iron and manganese removal systems use what chemical to remove sulfur compounds causing taste and odor problems?

Small dose of sulfur dioxide

The influent to a manganese greensand filter has a pinkish/orange color. What does this indicate?

Normal and will be removed by the filter

A pink color in the greensand filter effluent indicates?

Overdose of KMnO₄

Greensand filter effluent has a yellow to brownish color. Effluent has high iron and manganese content. What is the problem?

High Alkalinity

How would you correct the problem in question 18?

Reduce alkali feed; maintain pH during Cl₂, addition between 6.2-6.5.

How would you get rid of the red water that is in the distribution system?

Flush fire hydrants

Filter effluent clear, iron level low, and manganese level higher than raw water. What is the most likely cause?

Manganese leaching from greensand; bed is insufficiently regenerated