INTEGRATING HIGH-RATE DAF TECHNOLOGY INTO PLANT DESIGN

摘要

Compared with sedimentation, dissolued-air flotation (DAF) is a more efficient clarification process for separating floc particles, which are often low in density. This article investigates the use of short flocculation times with high DAF and filter hydraulic loading rates and examines the feasibility of integrating high-rate DAF technology into water facility design. Research was conducted at pilot scale using two water sources of varying conducted at pilot scale using two water sources of varying quality. Numerous runs were carried out under extremely conservative cold water conditions of 305 deg C.The most important research finding is that integration of high-rate DAF treatment technology is feasible. DAF treatment facilities may be designed and operated with flocculation times of 5 min, DAF hydraulic loading rates of 30-40 m/h (12-16 gpm/sq ft)depending on water temperature, and high filtration rates of 20m/h (8 gpm/sq ft).At higher DAF loading rates, excess air bubbles can be eliminated by internal or external air removal methods.