P a g e | 18including Microthrix parvicella, Bogiotae , and Sphaerotilus natans. The effluent in the biological unit was characterized by BOD5/COD ratio of 0.17 and COD removal efficiency of 53.32%. Those results demonstrated that the sewage treatment plant is frequently affected by bulking problems. This study had confirmed the importance of continuous monitoring of different process parameters like Wastewater Biodegradability Index, Dissolved Oxygen, filamentous flora, and Dilute Sludge Volume Index (DSVI) to avoid irreversible damage at the level of a wastewater treatment plant.