AWWA ACE91027

To facilitate a cost-effective filtration process, plant operators should maintain long filter runs, thus minimizing volume of wastewater generated, energy consumption, and the filter's downtime. In many instances, achieving such a goal requires application of a clarification process prior to filtration. Flotation has become an alternative to conventional and modern high-rate water clarification processes. This paper describes how dissolved air flotation works and presents some theoretical background. The author's product is also described. Situations in which dissolved air flotation would be useful are listed. Design requirements are outlined, with specific examples taken from pilot studies. Schematic drawings of a dissolved air flotation unit, and a drawing of the author's product, are given. Graphs show dissolved air flotation performance in response to increased loading, recycle rate, increased turbidity, and coagulant dose.