Biofilm models were used to model and predict the performance of Rotating Biological Contactors (RBC) in wastewater treatment plants. Assessment techniques have been adopted to evaluate this method in terms of hydraulic loading and Biochemical Oxygen Demand (BOD) removal. The results revealed that RBC not only is efficient, but also proven to be odor controlling reactor. RBC provides efficient mixing and reduces time of retention to minimum, so that a great reduction of area of treatment plants will be achieved.