The capability of submerged aerobic granular sludge membrane bioreactor (AGMBR) to remove organics and nutrients was studied in a 2 × 2 factorial experimental design. The hydraulic retention time (HRT) - 6, 8 and 10 h - and chemical oxygen demand (COD) - 298 ± 32, 543 ± 14, and 790 ± 33 mg/L - were the independent variables. AGMBR achieved >96%, 97%, 50%, and 35% removal for COD, NH3-N, total nitrogen, and PO4-P, respectively. Meganema and Thauera, responsible for organics degradation, were present during all the runs. Nitrosomonas and Nitrospira allowed for complete nitrification. The presence of Azoarcus and Thauera points to anoxic conditions in the granules, indicating partial denitrification. Negligible PAOs were detected; hence, low PO4-P removal (~35%) mainly via the consumption and biologically induced precipitation pathways. Overall, two runs - 298 ± 32 mg/L COD at 6 h HRT and 790 ± 33 mg/L COD at 6 h HRT - performed best in terms of organics and nutrients removal.
