It is commonly used for long term aeration and consists of a long elliptical or circularly shaped channel with aeration to generate flow and stirring.

Though it requires a relatively large area, it has a simple structure and can easily be operated as well as being able to remove nitrogen easily. Thus, it has recently been widely used in relatively small waste water treating plants.

Oxidation ditches can be easily maintained and are hardly affected by load fluctuations and forms only a little sludge. It can be easily controlled by changing the rotation of the rotor and the dipping depth. It requires relatively little energy as the rotor is operated efficiently and can perform denitrification and nitrification easily.