DAF-units are intended for the removal of hydrophobic contaminations such as lipoids, petrochemicals, suspended- and surface-active materials from wastewater. They are recommended for installation in the pulp-and-paper, food and oil-refining industries.
DAF-units - as part of a physiochemical treatment system - are used in preliminary treatment as well as for complete wastewater treatment. DAF – units can be used for separation and thickening of sludge compounds. DAF – units are intended for use in wastewater with a pH of 6.5 - 8.5.
DAF-units are manufactured from stainless steel AISI 304 (or AISI 316) in different dimension types, with capacity of 5 m3/h - 100m3/h. They feature a tank with an original shape, and provide the most effective water movement inside DAF-unit. Formation of floating systems, and their removal from the surface in the form of foam, is done inside the flotation chamber. A scraper mechanism for flotation sludge removal and a shoot for its drainage are installed in the top of the tank. Connecting pipes are provided for sludge removal at the bottom of the flotation installation chambers. A recirculation pump and equipment for reagent preparation is provided with the plant.
Wastewater is directed to the chamber of the DAF-unit at the same time that the working air-water mixture is also fed into the same chamber. This is done in order to aerate the saturated solution at the pressure drop. This gassing, in the form of micro bubbles, is done directly on the contamination particles and form strong floating sytems. Immersion of the floating systems then happens and a bubble layer comprising of extracted matters builds up on the liquid surface.. About 30% of the treated wastewater from this chamber is taken for preparation of a working air-water mixture. Air saturation of the water is done in the recirculation pump. The foam layer is removed by a scraper mechanism and drained by a shoot into a storage container for the floating slime. This process of floating system formation can be intensified by using different reagents (coagulants, flocculants) which promotes flotation process activation.
|Parameter||At reagent wastewater treatment, %|
|Fat and greases||Up to 98|
|BOD5||Up to 65|
The unit’s operation, including reagent equipment, is fully automated. Alarm systems of the normal operation indication and emergency stops are provided.It is possible to transfer equipment status data to a higher level automated process control system depending on the client’s requirements.