The filter effluent manganese values are higher than the filter inlet water, yet
the iron content is low and the filter effluent is clear. What is the problem with
the greensand filter?

Manganese being leached from the greensand media

Which polyphosphate chemical is more effective at lower dosages?

Sodium metaphosphate

Why is lime sometimes added to water that is being aerated?

Increase pH and help remove CO2

Looking at the plumbing fixtures to see if stains are present is a good way to
tell what?

If iron or manganese are present

What is the recommended detention time to allow the continuation of iron
oxidation after aeration?

30-60 minutes

Iron can be oxidized by aerating the water to form insoluble ferric hydroxide.
This reaction is accelerated by an increase in what?

•Aeration SCFM

•pH

•CO2

•Dissolved oxygen

Why must chlorine be fed along with polyphosphate?

To prevent iron bacteria from growing

In oxidation of iron using aeration, an increase in pH has what effect on the
reaction?

Accelerates the reaction

Problem with the manganese greensand filtration system. The effluent is
turbid with a yellow to brown color. The effluent iron and manganese results
are high. What is the cause of the filter problem?

The lime dose ahead of the filter is too high

Potassium permanganate is often used with what type of filtration media?

Manganese zeolite or manganese greensand

Pink colored filtered water from a greensand filter is an indication of what?

The permanganate dose is too high

Why should chlorine never be fed ahead of the polyphosphate?

The chlorine will oxidize the iron and manganese causing insoluble
precipitates to form too soon

Manganese greensand filters can be operated in three modes:
continuous regeneration, catalytic regeneration and what other method?

Intermittent regeneration

Which chemical is effective in oxidizing iron and manganese to insoluble
oxides?

Potassium permanganate