Aeration in water treatment is primarily used to remove what substances?

Aeration in water treatment is primarily employed to enhance the removal of dissolved gases and certain impurities, particularly iron and manganese, from water. These metals can cause discoloration, staining, and have undesirable tastes and odors in the finished water. During the aeration process, air is introduced into the water, which allows these metals to oxidize. The oxidized forms of iron and manganese become insoluble and can be more easily removed through subsequent filtration or sedimentation processes.

Iron is typically present in groundwater, and when it is oxidized, it forms rust, which clumps together and can be filtered out. Similarly, manganese oxidation results in the formation of particulate substances that are easier to separate from the water. This makes aeration an effective treatment step specifically for tackling these issues linked to iron and manganese, thereby improving water quality.