Integrating high-rate DAF technology into plant design

Compared with sedimentation, dissolved-air flotation (DAP) is a more effici ent clarification process for separating floc particles, which are often lo w in density. This article investigates the use of short flocculation times with high DAF and filter hydraulic loading rates and examines the feasibil ity of integrating high-rate DAF technology into water facility design. Res earch was conducted at pilot scale using two water sources of varying quali ty. Numerous runs were carried out under extremely conservative cold water conditions of 3-5 degrees C. The most important research finding is that in tegration of high-rate DAF treatment technology is feasible. DAF treatment facilities may be designed and operated with flocculation times of 5 min, D AF hydraulic loading rates of 30-40 m/h (12-16 gpm/sq ft) depending on wate r temperature, and high filtration rates of 28 m/h (8 gpm/sq ft). At higher DAF loading rates, excess air bubbles can be eliminated by internal or ext ernal air removal methods.