Extended aeration

Extended aeration is a method of sewage treatment using modified activated sludge procedures. It is preferred for relatively small waste loads, where lower operating efficiency is offset by mechanical simplicity. Extended aeration is a method of sewage treatment using modified activated sludge procedures. It is preferred for relatively small waste loads, where lower operating efficiency is offset by mechanical simplicity. Mechanized sewage treatment typically includes settling in a primary clarifier, followed by biological treatment and a secondary clarifier. Both clarifiers produce waste sludge requiring sewage sludge treatment and disposal. Activated sludge agitates a portion of the secondary clarifier sludge in the primary clarifier effluent. Remaining secondary sludge and all primary sludge typically require digestion prior to disposal.