Solid Liquid Separator Machine with Dissolved Air Flotation for ETP Oily Wastewater Our Solid Liquid Separator Machine (Model DAF-ETP Series) combines dissolved air flotation (DAF) technology with automatic surface skimming to deliver complete solid-liquid separation for ETP (Effluent Treatment Plant) systems. Fine air bubbles attach to suspended solids, oils and grease, floating them to the surface where a motorized skimmer removes them continuously - leaving clarified water