Secondary treatment - Mechanical system
Surface aerators are shown to provide aeration and mixing in the system.
The secondary treatment system depicts a conventional activated sludge system along with a denitrification system. The system is using surface mixers for aeration. The primary effluent enters the denitrification tank along with Return Activated Sludge (RAS) line and Nitrate recycle streams. The contents are then allowed to an aeration tank for organic removal and nitrification processes. The aeration basin contents are moved to a clarifier where the treated water is separated from the microorganisms by gravity settling. A portion of the sludge is wasted from the clarifier to keep low sludge blanket levels in the clarifier.