Aeration

Mixing air and a liquid by one of the following methods: spraying the liquid in the air, diffusing air into the liquid, or agitating the liquid to promote surface adsorption of air.
A process whereby water and air or oxygen are mixed.
The process of bubbling air through a solution, sometimes cleaning water of impurities by exposure to air.


Source: Handbook of water and wastewater treatment plant operations

Wikipedia:  https://en.wikipedia.org/wiki/Aeration