The balance between effluent quality, energy consumption efficiency, and greenhouse gas (GHG) emissions should be well maintained in modern wastewater treatment plants (WWTP’s). In this study, a novel process was employed to eliminate sidestreams from a full-scale anaerobic-anoxic-oxic (A2/O) WWTP, reducing carbon footprint and energy consumption while improving renewable energy production. The integrated plant processes were then modeled using GPS-X simulation, and the model was assessed using comprehensive data from a full-scale WWTP (A2/O) process. The results highlighted that the novel process increased renewable energy by 100 m3/day of biogas, equivalent to 214 kW. It also contributed to a high reduction in energy consumption by about 442.51 kW. Furthermore, the elimination of sidestreams has contributed to a 12 and 13% reduction in net carbon footprint and N2O released into the atmosphere, respectively. These results conclude that treating the sidestreams separately can improve the sustainable management of the A2/O WWTP.