A DAF system is short for Dissolved Air Flotation system. It helps purify wastewater. Wastewater is basically sewage or any nasty liquid. However, a DAF system can also be used to help purify other liquids, like gas and oil. DAF systems are also used in paper mills because water is needed to turn wood pulp into paper.
Here are more details about DAF optimization from World Water Works, Inc.
A DAF needs to remove any impurities from liquids, such as oils or solid matter from wastewater. Although they sound heavy, many modern DAF systems are made with lightweight polypropylene. This also makes the DAF system safe from corrosion for a long time, even from salt and acidic materials.
Chemicals like coagulants are added to the wastewater. These chemicals help separate impurities from water. Wastewater goes into advanced pipe floculators. These pipes twist and turn to help mix the chemicals into the wastewater. The pipes have ports at various locations so the water can be sampled to see if more chemicals need to be added.
Water with dissolved compressed air is also added to create bubbles in the wastewater, which helps separate impurities from the water. The impurities rise to the surface and are removed and placed into a waste hopper.