aeration zone in a sentence

1. Many sewage treatment plants use axial flow pumps to transfer nitrified mixed liquor from the aeration zone to the anoxic zone for denitrification.
2. In sewage treatment, an AFP is often used for internal mixed liquor recirculation ( i . e . transferring nitrified mixed liquor from aeration zone to denitrification zone ).
3. It's difficult to find aeration zone in a sentence.