In water treatment, aeration is the process which

Concept

Aeration is a gas–liquid mass-transfer operation. It increases contact between water and air so dissolved volatile substances can move between phases, while oxygen can drive oxidation reactions.

Application

Here, the defining mechanism is intensified air–water contact. Volatile dissolved gases such as carbon dioxide and hydrogen sulfide transfer from water to air; aeration can also oxidize iron and manganese. Therefore, the stated outcome is removal of excess and objectionable gases.

Contrast

• Readjusting pH is chiefly a chemical-conditioning operation using acid, alkali, or controlled carbon-dioxide removal.

• Large floc particles are normally separated by sedimentation and then filtration.

• Suspended solid particles are removed by clarification, sedimentation, or filtration according to their size and settling behavior.

Cross-check

The selected outcome matches the governing mechanism: increasing the air–water interface directly promotes transfer of volatile gases out of water. The other outcomes rely principally on chemical dosing or solid–liquid separation.