A water aerator is any of several devices used to add oxygen to water. Common types include air diffusion aerators, spray nozzle aerators, cone tray aerators, cascade aerators, and forced draft aerators. Water aeration is used commercially in water treatment and aquaculture, and is also used domestically for pond maintenance.
Photosynthesis usually accounts for the majority of natural aeration, and atmospheric diffusion is another natural source. These methods may supply insufficient oxygen to a water system, however, especially under cloudy, still conditions, or when too many or too few photosynthetic organisms are present. In such cases, it may be necessary to artificially add oxygen to the water through the use of a water aerator.
In water treatment systems, aeration is typically used to remove carbon dioxide, hydrogen sulfide, iron, and manganese. Artificial aeration is generally necessary in aquaculture operations to provide adequate amounts of dissolved oxygen for the fish. Aerators may also be needed in home ponds or water gardens to maintain desired plant or fish populations.
The purpose of a water aerator is to increase the surface area of water coming into contact with air. This allows more air to react with the water. Aeration can be accomplished by either moving water through air or moving air through water. The type of water aerator needed for a particular application depends on efficiency, the chemical properties of the water, and the reason for aeration.
Air diffusion is the main method of aeration, and involves moving air through water. In an air diffuser, water runs through a trough while compressed air is pushed upward from the bottom of it, thus moving the air through the water. This is a relatively inefficient method of aeration.
The majority of water aerators work by moving water through air. Some types, such as spray nozzle aerators, work by spraying streams of water through the air. Another type works by forming waterfalls, and two examples of this are cone tray and cascade aerators. In cone tray aerators, water flows through vertical cones and over the edges — this is primarily used to remove iron from water. Cascade aerators consist of a series of steps that water flows over in a thin stream, allowing more water to come into contact with the air.
A forced draft aerator combines the methods of moving air through water and water through air. In this type, water runs down a series of trays and drips off in small streams when it reaches the end, while at the same time a fan pulls air upward through the water. These aerators are useful for removing carbon dioxide and hydrogen sulfide from water.