AWWA ACE94258

The use of Dissolved Air Flotation (DAF) as a solid/liquid separation process in water treatment has been an effective alternative to sedimentation for 70 years. The process was initially applied for removal of materials which had a specific gravity less than water, such as fats, oils, fibers, and grease. DAF installations expanded in the late 1960s to wastewater and potable water treatment. Today, dissolved air flotation is utilized for a wide variety of water and wastewater applications. The technology is widely accepted in Scandinavia and the United Kingdom for potable water treatment. As a clarification process, dissolved air flotation has distinct advantages for waters containing: algae; color; supersaturated air; low temperature; low turbidity and limited alkalinity. Flotation has recently gained a foothold in the United States with the start up of a 7.5 mgd (28.4 Ml/d) potable water flotation plant in New Castle, New York. The goal of this paper is to present a summary of recent pilot and full scale activity in the United States and to describe recent retrofit activity in the United Kingdom. General design of a typical flotation and FLOFILTER process will be discussed.