Which method is used to improve the removal of certain contaminants in water through the addition of air?

The method used to improve the removal of certain contaminants in water through the addition of air is aeration. This process involves exposing water to air, which promotes the transfer of gases and allows for the elimination of volatile contaminants. During aeration, dissolved gases—such as carbon dioxide or hydrogen sulfide—can be released from the water, thus improving the water's quality.

Additionally, aeration can help in the oxidation of certain dissolved metals and organic compounds, converting them into forms that are more easily removed during subsequent treatment stages, such as sedimentation or filtration. By promoting chemical reactions and enhancing the oxidation-reduction potential of the water, aeration effectively reduces the concentration of harmful substances, making the water safer for drinking.

Filtration, chlorination, and precipitation are all important water treatment processes, but they serve different purposes and do not specifically involve the addition of air to improve contaminant removal as aeration does.