The paper reports the results of a laboratory investigation aimed at evaluating the effectiveness of an innovative technology, SBBGR (sequencing batch biofilter granular reactor), based on aerobic granular biomass, for treating diluted (i.e., municipal wastewater) or concentrated (i.e., municipal landfill leachates) wastewater. When this technology was applied to the treatment of municipal wastewater, the results showed that, even at maximum organic load (i.e., 7 (kg of COD)/m(3).d), the chemical oxygen demand (COD) in the treated effluent was lower than 50 mg/L. In addition, total Kjeldahl nitrogen (TKN) removal efficiency was higher than 87% up to an organic load of 5.7 (kg of COD)/m(3).d, corresponding to a nitrogen load of 0.8 (kg of TKN)/m(3).d. During the treatment of a mature municipal landfill leachate, the SBBGR proved suitable for removing the entire biodegradable compound content (i.e., about 80% of the COD content of the leachate) up to an applied organic loading value of 1.1 (kg of COD)/m(3).d. During the whole investigation, the process was characterized by a low sludge production, about I order of magnitude lower than that of conventional systems.