Shear And Aeration Activated Sludge Floc Stability

The desorption dynamics showed that the fine particles increased with time and reach the equilibrium at 180 min.Both desorption dynamics showed gradation changes before and after 400 r/min of agitation,and the corresponding value of air sparging was 0.4 m~3/h.This indicated the multi-layer structure of sludge flocs.The particle size of sludge decreased with the intensity of shear and sparging and the average decreases range was 35μm.The fractal dimension was 1.6-1.8 and decreased with intensity of shear and sparging,which indicated the looser structure.Evaluation the shear effects of air sparging was carried using contents of fine particles and fractal dimensions as investigation factors because of their fine relationships to the shear and sparging.The experience value of air sparging can be obtained by: G = 115.34V + 133.92.With increasing of intensity of shear and sparging SVI and sluge resistance increased and the trend was similar to the changes of fine particles.The shear effect of air sparging was higher than the agitation.The correlations of EPS and settlability and dewaterability of sludge was well under air sparging and poor under agitation.Under agitation and air spargeing systems,though the correlations of other factors to settlability and dewaterability were not unified,that of fractal dimensions was well.This meaned that the whole structure of sludge flocs was important for settlability and dewaterability...