Surface Aerators vigorously mix the incoming effluent with the activated sludge (aerobic bacteria) keeping it in suspension in the presence of supplied oxygen.

Micro-organisms in the sludge use the organic material in the effluent as a food source for normal life functions and synthesis of new bacterial cells.

Also whilst aerating a certain quantity of Waste Activated Sludge is removed and pumped to the Sludge Lagoons. “Nitrification” occurs during this stage which is the oxidation of ammonia to nitrite.