What process involves mixing water with air to remove contaminants?

The process that involves mixing water with air to remove contaminants is aeration. Aeration is commonly used in water treatment to enhance the removal of dissolved gases and certain contaminants such as volatile organic compounds (VOCs) and some metals. By exposing water to air, contaminants are allowed to escape into the atmosphere. This process not only helps in reducing concentrations of organic pollutants but also improves the taste and odor of the water by allowing unwanted gases to volatilize.

In contrast, filtration primarily focuses on physically removing particles and impurities from water through various media, and it does not involve the addition of air. Coagulation involves the addition of chemicals to agglomerate fine particles into larger clumps, which can then be removed during subsequent processes but also does not utilize air in the same way as aeration. Sedimentation is the process of allowing particles to settle out of water due to gravity, which also does not include the introduction of air to facilitate contaminant removal. Through the mechanism of aeration, the treatment process effectively cleans the water by leveraging the interaction between water and air.