Dissolved Air Clarifiers (DAF)

Wock-Oliver's DAF, Dissolved air floatation clarifier has been widely used for industrial wastewater treatment. The typical industrial wastes treated by flotation are paper mill backwater, oily wastewater as well effluents from sugar, dairy, textile industries and tanneries. Dissolved air flotation clarifiers or dissolved air flotation units (with 3 - 5 minutes of detention time) can replace sedimentation (with 2 - 3 hours of detention time) for clarification, has been overlooked by environmental engineers for many decades. Modern high rate DAF clarifiers have advanced to such an extent that they could overshadow conventional settling clarifiers in wastewater treatment. DAF hydraulic loading has increased from 1 L/m2.s to 2.5 L/m2.s and for a triple stacked unit to 7.5 L/m2.s. The detention time has decreased from 30 minutes to 3 minutes. Air dissolving is improved and now requires only 10 seconds retention time in the air mixing tube instead of the previous 60 seconds. The smaller size and weight of a modern DAF unit allow for inexpensive construction and flexibility of erection using prefabricated units. The availability of excellent flocculating chemicals gives a high stability of operation and high clarification degree.