What is the primary purpose of pressure aerators in water treatment?

• A. Remove volatile gases
• B. Add dissolved oxygen for a more pleasant-tasting water
• C. Oxidize iron and manganese
• D. Oxidize organic material

Answer: (C)

Pressure aeration introduces air into water under pressure, promoting the oxidation of dissolved iron and manganese. When iron is oxidized from Fe2+ to Fe3+, it forms ferric hydroxide precipitates (Fe(OH)3) that are insoluble and can be removed by filtration or settling. Similarly, manganese is oxidized to manganese dioxide (MnO2), which also precipitates and can be filtered out. This OPENS the door to effective removal of these metals from the water, reducing rust staining and turbidity. While aeration can also increase dissolved oxygen and help with some gas stripping, the primary design purpose in this context is turning soluble iron and manganese into removable solids. Oxidation of organic material can occur with aeration, but it’s not the main goal for pressure aerators in most treatment schemes.