In the Air Head Composting Toilet, once solid matter enters the main tank, foul-smelling anaerobic bacteria die off in a few days due to the presence of air. This creates an environment for non-odorous aerobic bacteria to thrive. This process works best when urine is separated, as in the Air Head, which maintains an optimal carbon/nitrogen ratio for aerobic bacterial action. Solids are moved under the composting medium and agitated to encourage these aerobic bacteria, which act as a natural odor filter. The result is a minimal, earthy scent, managed by the included external fan and vent. This vent can be installed through external walls or ceilings, and for boats, venting into an anchor locker with external air passage is effective.