Aerobic granular sludge: Cultivation parameters and removal mechanisms.

Highlights • Parameters of AGS formation were reviewed, and reference values were proposed. • Parameters of AGS maintenance were reviewed, and reference values were proposed. • The main metabolic pathways for removal of some compounds by AGS were discussed. • Microbial groups present in AGS and their respective functions were discussed. • The favoring strategies for AOB, NOB, PAO and GAO in AGS were proposed. Abstract Aerobic granular sludge (AGS) has been the focus of many investigations, and the main parameters responsible for AGS formation are hydrodynamic shear force, short periods and feast-famine cycles. However, some other parameters are associated with AGS maintenance after long periods of operation. This review evaluates the parameters responsible for AGS formation and maintenance and some reference values are proposed. In addition, some discussions are addressed about the main metabolic pathways that AGS uses for the removal of some compounds, such as nutrients, organic matter, dyes, recalcitrant compounds, among others. Finally, the main microbial groups present in the AGS and their respective functions are discussed. It is also highlighted that many parameters that are taken as reference currently for AGS cultivation and maintenance can be optimized for energy savings, implementation costs, among others, as well as a greater recovery of resources during wastewater treatment, within the scope of the biorefinery concept. [ABSTRACT FROM AUTHOR]