Flotation

Dissolved air flotation is used for thickening of sludge that originates from suspended growth biological treatment processes. It involves the introduction of air into a sludge solution that is being held at an elevated pressure. When the solution is depressurized, the dissolved air is released as finely divided bubbles. These carry the sludge to the top, where it is skimmed. Solids concentration achieved is between 3.5-5%.