aerobic

Aerobic process or environment is one in which is a sufficient amount of molecular oxygen. The amount of oxygen is evaluated primarily according to the needs of microorganisms that live in that environment. 

The opposite of aerobic is anaerobic environment. It is an environment where molecular oxygen is absent or in very small concentrations.

Aerobic conditions are optimal when the oxygen concentration in the free atmosphere of the monitored environment (eg compost) is over 14 %. Sufficient conditions for most aerobic microorganisms are even at concentrations up to 3 %, the next downturn occurs a transition to anaerobic environments.