This paper presents the results of a study in which a pilot scale five-stage biological nutrient removal system with an active volume of 8.6 m3 was operated with two different processes to remove carbon and nutrients from domestic wastewaters. During the application of both processes, hydraulic retention time was 16.08 hours, MLSS concentration was between 4500 and 5500 mg/L, and sludge age was about 15 days. The sludge volume index (SVI) ranged from 50 to 150 mL/g. Both processes were evaluated in the aspect of their performances for COD, TKN, NH4-N, TP, PO4-P, SS, and VSS removal efficiencies. The removal efficiencies for the first process, which is a new process (A – Modified Five-Stage Bardenpho process), were 86.5%, 85.5%, 92.7%, 88.9%, 88.1%, 93.7%, and 93.5%, respectively for COD, TKN, NH4-N, TP, PO4-P, SS, and VSS, while the removal efficiencies were 86.7%, 84.0%, 92.5%, 89.5%, 87.5%, 94.8%, and 95.0%, respectively, for the second process (B – Two- Stage, Cascade Biological Nutrient Removal process). The results suggested that both processes are suitable for carbon and nutrient removal from domestic wastewaters and they can be employed in full-scale treatment plants.