Optimizing dissolved air flotation design system

Dissolved Air (Pressure) Flotation-DAF, is a well-Established separation pr ocess that employs micro-bubbles as a carrier phase. This work shows result s concerning bubble generation at low working pressures in modified DAF-uni ts to improve the collection of fragile coagula by bubbles. DAF of Fe (OH)( 3) (as model) was studied as a function of saturation pressure in the absen ce and presence of surfactants in the saturator. DAF was possible at 2 atm by lowering the air/water surface tension. This fact, which leads to substa ntial energy savings, was explained in terms of decreasing the "minimum" en ergy required for bubble nucleation and cavity in the nozzle. More, bubbles -fragile coagula attachment was improved by dividing the recycling water in to two: 1) the inclined inlet to the cell (traditional) and 2) inside the s eparation tank through a water flow inlet situated below the floating bed u sing a "mushroom" type diffuser. Because of the reduction observed in the d egree of turbulence in the conventional collection zone, DAF performance im proved yielding high precipitate recoveries.