DAF oil recovery


(Translation: Recovered DAF oil means recovered dollars.)

Alfa Laval offers innovative specialty and traditional by-product processing solutions for waste stream oil recovery. The Centriskim module provides an inexpensive solution for reducing DAF skimmings to recovered fat and an easily disposable water phase.

How Dissolved Air Flotation (DAF) works

DAF separates particles such as fat and oil from wastewater in animal processing. The wastewater, containing fats and proteins, is agitated in a cell or vat, during which millions of tiny bubbles rise to the surface. The Centriskim skims off the froth of bubbles and sends it to a steam heater. After the skimmings are heated, they are then separated by one of the following methods:

  • Single-stage separation using a three-phase decanter to extract solids, fat, and water
  • Two-stage separation, which requires a two-phase decanter for the solids/liquid split and a high-speed separator to extract the fat

Once separation is completed, the recovered fat can be processed into biodiesel; the recovered protein can be made into animal feed; and the water is either returned to the DAF cells or disposed of using an evaporator, such as the AlfaVap.

  1. DAF cell
  2. Buffer Tank
  3. Steam Heater
  4. Decanter


Which separation method is best?

Single-stage separation, using a three-phase decanter, is preferable in cases where the composition and consistency of the DAF skimmings are fairly consistent. Two-stage separation, with a decanter and a high-speed separator, is a more versatile and efficient method, which provides the best separation performance on products with more variations in composition, quality, and chemicals. The fat complies with more demanding specifications, and the remaining water has a lower BOD loading.


Centriskim benefits

Centriskim modules are flexible and can be tailor-made to meet specific requirements, to best suit your needs and budget. Features include:

  • Cost-effective
  • Compact size
  • Automation
  • Chemical cleaning station
  • Optional sizing equipment