University of Guilan Caspian Journal of Environmental Sciences 1735-3033 19 4 2021 10 01 Evaluating the efficiency of municipal wastewater treatment plant in AL-Dhibaei, Iraq 753 758 5150 10.22124/cjes.2021.5150 EN Bashar Tareq Al-Shandah Department of Biology, College of Science, University of Tikrit, Iraq Haneen A. Kh. Karaghool Department of Environmental Engineering, College of Engineering, University of Tikrit, Iraq Waleed M. Sh. Alabdraba Department of Environmental Engineering, College of Engineering, University of Tikrit, Iraq Journal Article 2021 11 03 In this study, municipal wastewater treatment plant (WWTP) in AL-Dhibaei, Tikrit, Iraq was monitored over a period of one year. The data of raw sewage, which enter WWTP and treated sewage were obtained and investigated. To assess the operational performance of WWTP, the necessary pollutant indicators including biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), and dissolved phosphorus (PO₄), were examined. The treatment plant reliability factor (RF) was determined in order to indicate an individual pollutant in the effluent sewage according to the permissible concentrations identified by the Iraqi Ministry of Health and Environment. RF values for BOD, COD, and PO₄ were 0.56, 0.82, and 0.4, respectively, which indicated proper performance since RF values below 1. In addition, the removal efficiency for (BOD, COD, and PO₄), exceeded the minimum required reduction; 43.75, 18.25, and 60.5, respectively. In addition, the stability of mixed liquor volatile suspended solids (MLVSS) to mixed liquor suspended solids (MLSS) ratio was determined and its variation was in the range of 0.565-1.225, indicating a proper performance. The sludge volume index (SVI) values were below 50 mg L^-1 and its range (5.68 – 27.27 mg L^-1), which was associated with efficient treatment interpretations at most of the time. https://cjes.guilan.ac.ir/article_5150_10e57c9e36365dbd241ff7267a6ef1ea.pdf