The unit technology uses extremely small air bubbles to lift suspended solids and oil to the top surface. The formed sludge layer is scraped into a sludge holding tank. The addition of coagulation and flocculation chemicals may be required to enhance the performance. Removal efficiency is usually superior to gravity bases systems and often applied as polishing step (downstream of CPI) The unit can be supplied with a gas-tight cover, coagulation & flocculation dosing and mixing equipment and air-saturation by special pumps or in separate pressure vessel. Flotation consists of separating solids from the water phase by attaching the solids to fine air bubbles to decrease the densityof the particles which float instead of sinking. The rising solids are called the and are skimmed off the surface and further processed in the sludge train.Chemicals can be added to improve the separation: first for coagulation and then for flocculation. The type of flotation used by Dissolved Air Flotation in which the suspension is saturated with air at high pressure. Bubbles are released to the water and will attach to the suspended solids.The bubbles from a system are much smaller than in other types of flotation systems and better adhere to the solids.This makes one of the most efficient flotation options of wastewater treatment.
