A review of aerobic granular sludge (AGS) treating recalcitrant wastewater: Refractory organics removal mechanism, application and prospect

Recent years have witnessed the rapid development of polluting industries as well as enormous production of recalcitrant wastewater containing toxic and refractory compounds. An innovative biotechnology - aerobic granular sludge (AGS), exhibits a notable potential for making contributions to the effective treatment of recalcitrant wastewater. AGS is a particular type of biofilm developed without carrier materials. With eminent biomass retention, the layered structure and extracellular polymer substances matrix endow AGS with high resistance to toxicity and heavy pollutants loading. This review analyzes the structure of AGS in terms of recalcitrant wastewater treatment and the biodegradation of a series of representative refractory organics with drawing attentions to the biodegradation mechanisms. The applications of AGS to the treatment of recalcitrant industrial effluents are discussed as well. Whilst the combination of AGS with chemical pre-treatments aiming at promoting the biodegradability of wastewater is an economically feasible alternative, the combination with membrane bioreactor seems to have a promising prospect but demands further investigation. (C) 2021 Elsevier B.V. All rights reserved.