FLOTATION PROCESSDAFTECH Floatcells are circular in shape, ranging in diameter from 1.2 to 16.8 meters and a liquid depth of only 0.65 meter. The complete set up consists of a flotation tank, feed pump, pressure pump, compressor, air mixing tube, chemical feed system and a spiral scoop for collection and removal of floated sludge.
The inlet, outlet and sludge removal mechanisms are contained in the central rotating section. This section and the spiral scoop rotate around the tank at a speed synchronized with the flow. The system is operated in the recycle flow pressurization mode where a portion of clarified effluent (25 - 30 percent) is continuously recycled from the DAF tank to the air mixing tube at about 6.5 bar pressure. After pressure release, the aerated water is mixed with the influent flow just before the inlet to the distribution duct that moves with the same velocity, but in opposite direction to the incoming flow thus creating a quiescent state in the flotation chamber. Fine bubbles generated in this manner attach to the suspended particles and make them float to the surface.
The spiral scoop takes up the floated sludge, pouring it into the stationary center section where it is discharged by gravity. Clarified water is removed by extraction pipes, which are attached to the moving center section and discharged. Wiper blades attached to the moving distribution duct scrape the bottom and the sides of the tank and discharge settled sludge into the built-in sump for periodic purging. Variable speed geared motors drive the rotating elements and scoop. Electrical current for the geared motors are fed from a rotary contact mounted on the central shaft.