Tapered Aeration

Tapered aeration is a modification of the conventional plug-flow procedure. Varying aeration rates are applied over the tank length and depending on the oxygen demand. A greater amount of air is supplied to the head end of the aeration tank, and an amount diminishes as the mixed liquor approaches the effluent end. Tapered aeration is commonly achieved by using different spacing of the air diffusers over the tank length.

                              Figure 15: Tapered Aeration Activated Sludge Process