Aeration towers are used to reduce the main type of pollutants found in the water from the Milan wells– chlorinated solvents and volatile organic compounds (V.O.C.).

In the past, the content of these compounds exceeded the maximum allowable concentrations (MAC) and it was necessary to come up with viable control solutions.

Being volatile, chlorinated solvents are easy to eliminate using aeration: within the towers, the water is sprayed upwards and comes into contact with the clean, filtered air stream blown up by fans. This way, the undesired volatile compounds are transferred from water into the air. This treatment achieves or exceeds 95% efficiency.

The "stripping" action of the air also works against other substances found in water, such as carbon dioxide (CO2), which is partly restored by injection before the water is pumped into the waterworks piping system.