Aeration is used for many purposes in water Treatment , the main uses are: 1. Increase the dissolved oxygen concentration in water. 2. Decrease CO2 concentration thereby reduce its corrosiveness. 3. Reduce taste and odor caused by dissolved gases such as Hydrogen sulphide (H2S) and methane (CH4) that are removed during aeration. 4. Oxidize iron and manganese from their soluble to insoluble states and cause them to precipitate so that they maybe removed by sedimentation and filtration processes. 5. Remove certain volatile organic compounds.