Characterization of the dewaterability of excess aerobic granular sludge

Abstract

Aerobic granular sludge technology has emerged as a promising wastewater treatment process. However, downstream granular sludge management framework is still challenging and lacks sufficient scientific coverage. This research aims to elucidate the dewatering characteristics of aerobic granular sludge compared to activated sludge. Several parameters, such as zeta potential, specific resistance to filtrate, capillary suction time, bound water content, and rheological behavior, were employed to obtain a comprehensive understanding of the dewatering capability of targeted sludge types. The results indicate that aerobic granular sludge has a higher demand for flocculant polymer than activated sludge (1.07 - 3.40 times). Additionally, aerobic granular sludge demonstrates higher resistance to filtrate (1.22 ± 0.09 - 6.59 ± 0.36 ×1011 m/kg) compared to activated sludge (2.93 ± 0.09 ×109 m/kg). The resistance to filtrate was shown to be positively associated with the average granules size. The usage of flocculant polymer significantly reduced the resistance to filtrate of all targeted samples. The bound water content of granular sludge (1.83 ± 0.37 - 4.31 ± 0.15 g/g TS) was higher than that of activated sludge (0.75 ± 0.13 g/g TS). According to the rheological data, aerobic granular sludge has a slightly higher apparent viscosity than activated sludge. The results of this study provide valuable insights into the potential implications of aerobic granular sludge dewatering at full-scale applications.