Dissolved Air Flotation

Though dissolved air flotation (DAF) has been used for drinking water clarification in Europe since the late 1960s, it is still somewhat new or unknown to many drinking water treatment professionals in North America. Wastewater treatment professionals, however, do recognize DAF as a well-established sludge thickening process that's also proficient at removing oil and grease from industrial wastewater.

DAF is an alternative clarification process that uses micro air bubbles to attach and float flocculated particles and suspended solids to the water surface for removal (see Fig. 1). In contrast, sedimentation removes settled solids from the bottom.