Aeration is a process used in water treatment to add air into water, allowing aerobic biodegradation of organic materials and removal of dissolved gases. Aeration is an essential part of the wastewater treatment process, as it accelerates the sludge process and promotes microbial growth using the naturally occurring elements already in the wastewater. Aeration is used in the secondary treatment process of municipal and industrial wastewater treatment, where it is based on pumping air into a tank, which promotes the microbial growth in the wastewater. The microbes feed on the organic material, forming flocks which can easily settle out. A well-designed aeration system has a direct impact on the efficiency of the wastewater treatment, reducing the length of the process, increasing energy efficiency, and cutting costs.

Aeration is also used in drinking water treatment to reduce the concentration of volatile organic compounds, dissolved gases such as radon, carbon dioxide, some taste and odor problems such as methane, and hydrogen sulfide, as well as to oxidize dissolved iron. Aeration treatment consists of passing large amounts of air through water and then venting the air outside. The air causes the dissolved gases or volatile compounds to release from the water. The air and the contaminants released from the water are vented. In the case of iron and manganese, the air causes these minerals to move from their dissolved state to a solid state and precipitate out of solution.

Aeration is also used in industrial water conditioning to remove carbon dioxide, oxidize soluble iron and manganese to insoluble precipitates, and reduce the carbon dioxide liberated by a treatment process. Aeration is a simple tool and speeds up the natural elements towards keeping a healthy ecosystem balance. When the balance is offset, the evidence is seen in sludge-filled waterways, algae-laden lakes and rivers, and polluted oceans.

In summary, aeration is a process used in water treatment to add air into water, allowing aerobic biodegradation of organic materials and removal of dissolved gases. It is an essential part of the wastewater treatment process, and it is also used in drinking water treatment and industrial water conditioning.