摘要：Floc recycling flocculation (FRF) derived from traditional flocculation (TF) is a controversial, but widely used, technology to enhance the removal efficiency of contaminants. In this study, the effect of floc recycling on zeta potential, residual turbidity and floc characteristics was made via a comparison between FRF and TF with a series of polymeric aluminium chloride doses. Compared with TF, the high coagulant dosage caused higher zeta potential in FRF, and the residual turbidity was optimized by charge neutralization and deteriorated at the high dosage of coagulant. The floc growth and physical characteristics were analysed with pictures captured by a high speed imaging system. The results showed that, by FRF, larger flocs were formed, and the formation rate was improved. However, floc recycling weakened the strength of flocs at low coagulant dosage (< 0.008 mmol.L-1), but strengthened ^ocs at high doses (> O.Olmmol.L-1). Floc size recovery was better at charge neutralization and worsened above0.015mmol.L-1. The fractal dimension of final flocs in FRF was superior to that in TF at low dosage, and the concentration of small flocs following FRF was much less than TF.
