Dissolved Air Flotation
Dissolved air flotation is one type of solid liquid separator typically used for treatment of wastewater and drinking water. A simplified overview of the process is the addition of coagulants and attachment of air bubbles to the solid aggregates causing the solids to float where they are removed from the water.
There are many wastewater applications for the DAF process. Essentially any waste water stream that has a high solids load can be clarified to produce a cleaner wastewater that can be discharged to a sewer. The DAF can reduce the costs of discharge licenses and saving more than the DAF operational costs.
Typical applications
Abattoirs Food manufacturers
Animal processing Dairy processing
Commercial kitchens Tanneries
WAS and municipal WWTP Drinking water
Shopping centres
Recently changed legislation requires that traditional grease traps must be replaced with DAF treatment systems in shopping centres which have food courts, cafes and restaurants to remove solids from the wastewater. A centralized DAF can treat all wastewater generated on site.
Drinking water
Water supplies that are vulnerable to unicellular algal blooms or with low turbidity and high colour can use a DAF treatment system. The DAF is supplied with reaction tanks to adjust pH and create coagulation. After the coagulation and flocculation processes, water flows to dissolved air flotation tank(s) where air diffusers on the tank bottom create fine bubbles that attach to floc. The floc becomes more buoyant and floats to the water surface. The gathering floating mass of concentrated floc forms a blanket which is removed from the surface. The remaining water is now clarified withdrawn from the bottom of the DAF tank.