CWS Iron, Manganese & Hydrogen Sulfide Removal 3

Question 1

What is the primary difference between 'clear-water' iron and 'red-water' iron?

Accepted Answer

Clear-water iron is ferrous (dissolved); red-water iron is ferric (oxidized particulate)

Answer

Clear-water iron is ferric; red-water iron is ferrous

Answer

Clear-water iron has a higher pH; red-water iron has a lower pH

Answer

There is no meaningful difference in treatment approach

Question 2

Hydrogen sulfide in well water is most effectively removed by which treatment approach?

Accepted Answer

Aeration or chlorination followed by filtration

Answer

Water softening with ion exchange resin

Answer

Reverse osmosis membrane filtration alone

Answer

Adding pH-adjusting chemicals

Question 3

Which water condition is most likely to keep iron in dissolved ferrous form and prevent natural oxidation?

Accepted Answer

Low pH and low dissolved oxygen

Answer

High dissolved oxygen and high pH

Answer

High pH and high alkalinity

Answer

High temperature and high total dissolved solids

Question 4

A water sample tests at 0.6 mg/L iron and 0.08 mg/L manganese. Which statement correctly describes these results against EPA secondary standards?

Accepted Answer

Both exceed EPA secondary standards

Answer

Both are within EPA secondary standards

Answer

Iron exceeds the SMCL; manganese is within limits

Answer

Manganese exceeds the SMCL; iron is within limits

Question 5

Which aeration system design is most effective for removing high concentrations of hydrogen sulfide gas from water?

Accepted Answer

Packed tower aeration or spray aeration open to atmosphere

Answer

Diffused air injection directly into the pressure tank

Answer

Adding sodium hypochlorite inline without aeration

Answer

In-line venturi aeration fitting on the service line

Question 6

Tannins in source water can interfere with iron testing results by:

Accepted Answer

Producing falsely elevated total iron readings

Answer

Precipitating iron before the test is completed

Answer

Causing artificially low readings due to color masking

Answer

Completely neutralizing the colorimetric test reagents

Question 7

When sizing an iron removal system for a residential installation, which factor is MOST critical to establish first?

Accepted Answer

Total iron concentration and household peak flow rate requirements

Answer

Static water pressure at the point of entry

Answer

Age and material of the existing plumbing system

Answer

Temperature of the incoming water supply