raw wastewater is first screened before
entering the oxidation ditch. Depending on the
system size and manufacturer type, a grit chamber
may be required. Once inside the ditch, the
wastewater is aerated with mechanical surface or
submersible aerators (depending on manufacturer
design) that propel the mixed liquor around the
channel at velocities high enough to prevent solids
deposition. The aerator ensures that there is
sufficient oxygen in the fluid for the microbes and
adequate mixing to ensure constant contact between
the organisms and the food supply (Lakeside,
1999).