Motor driven, mechanical aerators provide a combination of liquid
aeration and mixing. Some mechanical aerators produce the gas - liquid interface
by entraining air from the atmosphere and dispersing it into bubbles. Other
types disperse liquid in the form of droplets or they produce jets or thin films
that contact the ambient air. Some other types even generate both liquid
droplets and air bubbles.
Some of the factors to consider about mechanical aeration include the geometric and dynamic parameters, and composition and temperature of the process water.
For more information on the use of mechanical aerators one may consult the Water Pollution Control Federation's Manual of Practice FD - 13 entitled "Aeration".