Enhanced Granulation of Aerobic Granular Sludge by Al3+ Augmentation at Low Temperature

Abstract:

A study was made of the enhanced granulation of aerobic granular sludge (AGS) by Al 3+ augmentation at low temperature. Rapid granulation was achieved since AGS formation time significantly decreased from 73 days to 40 days by adding 30.0 mg·L-1Al3+ at low temperature in a sequencing batch airlift reactor (SBAR). AGS with clear surface and compact structure possessed better settling property, higher biomass, and better simultaneously COD, NH4+ N and PO3-4 P removal efficiency, the respective removal rates were 85.6%, 88.8% and 91.9%. Compared with the conventional cultivation of AGS, the content of total protein was as high as 9.25 mg·g-1 and the total proteins to the total polysaccharide(PN/PS) ratio was 1.10, and the relatively high protein content presented an essential feature for AGS formation. In addition, zeta potential increased from -18.40 mV to -6.51 mV when AGS became mature by adding 30.0 mg·L-1 of Al3+, the higher zeta potential indicated the reduction of electrostatic repulsion was beneficial for granules aggregated.