RESUMO
Two sequential batch reactors (R1 and R2) of aerobic granular sludge (AGS) were inoculated with activated sludge of different origins. The objective was to investigate the granulation and the consistency between the structure of the microbial communities (16S rRNA amplicon sequencing) in each reactor and their metabolic performance (removal of C, N, and P). Both reactors were fed with acetate-based synthetic wastewater, targeting an anaerobic-aerobic cycle reputed to favor the phosphorus- and glycogen-accumulating organisms (PAO and GAO). Stable granulation was achieved in both reactors, where, instead of PAO, the dominant genera were ordinary heterotrophic organisms (OHO) such as Thauera, Paracoccus, and Flavobacterium known for their high capacity of aerobic storage of polyhydroxyalkanoates (PHA). Generally, there was good consistency between the metabolic behavior of each reactor and the bacterial genera detected. Both reactors showed high removals of C and complete nitrification (Nitrosomonas and Nitrospira detected) but a low level of simultaneous nitrification-denitrification (SND) during the aerated phase. The latter causes that nitrates were recycled to the initial phase, in detriment of PAO selection. Meanwhile, the study showed that selecting slow-growing OHOs (with aerobic storage capacity) favors stable granulation, revealing an alternative AGS technology for C and N removal.