Effects of carbon source on the formation, stability, bioactivity and biodiversity of the aerobic granule sludge

•The impact of carbon sources on formation and stability of the AGS was evaluated.•Acetate granules presented better results but partial disintegration was observed.•Ethanol promoted the formation of stable granules, but low P removal was observed.•Glucose caused the lowest microbial diversity and filamentous bacteria formation. Three aerobic granular sludge systems were operated as sequencing batch reactors (SBR) with acetate, ethanol and glucose as carbon source. The SBR cycle was 6 h, with an anaerobic phase followed by an aerobic phase. The acetate granules (>1.5 mm) had the greatest microbial diversity and better results in terms of removal efficiency for carbon and nutrients (TN ≈ 72% and TP ≈ 42%) and also in the resistance tests. However, partial disintegration was observed. On the other hand, when ethanol was the substrate, the granules were stable, good nitrogen removal was achieved (TN ≈ 53%), but phosphorus removal was not favored (TP ≈ 31%). Glucose presented the lowest efficiency values for nitrogen (TN ≈ 44%) and phosphorous removal (TP ≈ 21%), and the granules formed (