Aeration is a unit process in which air and water are brought into intimate contact. Turbulence increases the aeration of flowing streams (Figure 4-1). In industrial processes, water flow is usually directed countercurrent to atmospheric or forced-draft air flow. The contact time and the ratio of air to water must be sufficient for effective removal of the unwanted gas.

Aeration as a water treatment practice is used for the following operations:

·         carbon dioxide reduction (decarbonation)

·         oxidation of iron and manganese found in many well waters (oxidation tower)

·         ammonia and hydrogen sulfide reduction (stripping)

Aeration is also an effective method of bacteria control.