Aqua Engineering DAF system

A DAF (dissolved air flotation) system for treating or refining wastewater, engineered in Europe to EU standards, has been introduced to Australia.

Applications for the DAF include dairy and cheese factories, the paper industry, food industry, oil industry, wineries, tanneries, textile industry, large laundries, chemical industry, refineries, sludge thickening, and primary and secondary clarification in municipal and industrial biological wastewater plants.

Each DAF system incorporates a CST-supplied SAT air dissolving reactor, which is the key to the dissolved air flotation process. The SAT generates the micro bubbles that separate and thicken the suspended solids. Its double-injector air dispersal method results in good dissolving air efficiency up to 90%.

The first stage of air dissolving, up to a theoretical maximum saturation of 50%, occurs in the high-turbulence, high-intensity mixing zone of the central tube inside the vessel.

The second stage occurs in the larger volume of this vessel, where longer air-liquid contact provides a large exchange with very fine bubbles and a high exchange surface. The added 30-40% dissolution takes places during this second stage.

Raw wastewater, mixed with air saturated recycle stream, is introduced into the main body of the flotation tank through a series of openings located around the circumference of the lower part of the central column.

Solids are rapidly carried to the surface by the micro bubbles and are evenly distributed as sludge on the surface of the flotation tank in a uniform hydrodynamic condition.

The sludge float is then removed by a rotating adjustable scroll scoop or by a surface skimmer, without disturbing the sludge blanket.

The DAF system’s designer, Aqua Engineering, has built more than 400 wastewater treatment units over a 30-year period.