DAF: Its place in an integrated plant design

The purpose of this paper is to highlight the potential for the use of flotation in a wide number of applications somewhat more diverse than those typically associated with dissolved air flotation and normally applied within the British Isles. DAF has typically been seen as appropriate for low turbidity, impounded or non flashy waters, requiring fairly conventional flocculation and followed by single or two stages of filtration depending on the final required water quality. Rates applied have remained essentially unchanged since the process was first introduced[1] into this country in the early 1970's. Recent work carried out and reported elsewhere[2][3] has shown that flocculation times, flotation and filtration rates typically used could on occasions be deemed to be ''conservative''. Generally the rates applicable to any scheme should be based not only on the characteristics of the raw water but also on the individual components which go to make up any particular plant.