The pre-treatment AAQUA-DAF (Dissolved Air Flotation) is a widespread technique for the purification of wastewater.

Once the wastewater is filtered, additional oil, grease and suspended solids can be removed with high efficiency by means of an Aaqua-DAF.

The technique of flotation is often combined with a prior physico-chemical treatment, using a coagulant (FeCl3 or PAC) and a flocculant (Polymer). This transforms certain solutes (eg: proteins, heavy metals) into flocs and  this technique can also break down emulsions,  which increases the efficiency of the oil and grease removal.

Depending on the type of wastewater, COD removal efficiencies between 30 and 95% are achieved.

The AAQUA-DAF is often used:

  • As a treatment prior to aerobic purification and to avoid oil and grease in to the aerobic treatment
  • As a phosphate and heavy metals removal step
  • In slaughterhouses and  the food industry
  • In the chemical, petrochemical and tank cleaning industries
  • As a discharge of an existing biological treatment
Suspended solids, fats and oils can be removed using a dissolved air flotation (DAF) unit. The buoancy force of the microscopic air bubbles (20 tot 50 micron) lifts the suspended solids up to the surface. This floating sludge is thickened by means of a sludge-thickening grid. The partly dewatered sludge is then skimmed into the sludge compartment.
The dry solid content of the sludge can be adjusted by a simple level controller and the motion speed of the skimmer.
The water, supersaturated with dissolved air, is produced in a pressure vessel. The water used in this vessel is recycled from the processed waste water from the effluent compartment.

In certain cases an Aaqua-DAF can be equiped with an additional plate package to obtain a maximum suspended solids removal.

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