Aerated lagoons have mechanical aerators which minimize anaerobic zones by completely mixing the lagoon to achieve catabolism through a process called extended aeration.
When the fuel level fell below critical (about 3 gallons), sloshing would cause the pump to pick up a slightly aerated mixture which was sent to the fuel distributor.
Towards the end of the nineteenth century, pneumatic malting was introduced, in which the barley is aerated and the temperature carefully controlled, accelerating the germination.