AGS from previously operated laboratory-scale SBRs was used to inoculate two 1.5-L SBRs (H/D = 2.5) after a 2.5-month storage period. The new reactors were operated for 315 days, comprising six experimental periods (A–F), characterized in Table 1. Filling was performed from the bottom of the reactors (Figure 1): as a plug-flow regimen in SBR2, allowing the feed to spread through the sludge bed; or at a peripheral site at the bottom of SBR1, the feed rapidly channeling across the settled biomass with no relevant contact between them. Both SBRs were operated in 6-h cycles including a 30-min static anaerobic feeding in SBR1 (no distribution of the feed through the sludge bed) and a 50-min static plug-flow feeding, through the sludge bed, in SBR2 (changed to 1.3-h in SBR2 from day 180 on), followed by a 1.5-h stirred anaerobic phase (changed to 1-h in SBR2 from day 180 on), 3.5-h aeration, 5-min settling, 1-min drain and idle. Mechanical mixing was provided by an anchor-like impeller at 70 rpm and by a 4-blade axial impeller at 280 rpm in SBR1 and SBR2, respectively, and aeration was supplied by air compressors via porous bottom diffusers (Figure 1).