Wastewater characterization is a constitutional part of treatment and schemes for city effluent. The aims of this research are to show the characterization and removal efficiencies of Hamadan wastewater treatment plant which is located in the south of Iraq. This study was carried between 2009 and 2010. Hamadan wastewater treatment plant was designed in 1979 and firstly operated on 2005. The assessment of wastewater treatment plant was aspired to demonstrate the characteristics of the influent wastewater to the treatment plant, the quality of the effluent from the treatment plant and the efficiency of the treatment units. The qualities of the treated effluent were ranged as follows: pH values across all study period ranged between 7.1 and 7.8. The concentrations of biological oxygen demand (BOD) and chemical oxygen demand (COD) varied from 100 to 242 mg/L and 225 to 936 mg/L, respectively. Total suspended solids (TSS) of the months during the study period were in the range of 176-924 mg/L. Oil and grease concentration in this study varied from 70 to 658 mg/L The results mostly show a negative impact of discharging treated effluent on the receiving lands. Results of primary treatment of Hamdan wastewater treatment suggested that the primary treatment alone was not adequate to reduce pollutant loads significantly. Hence, biological treatment was demanded to meet local effluent quality standards.
