M Aalami - School of Water & Waste Water Engineering, College of Water Engineering, Power & Water University of Technology, P.O.Box ۱۶۷۶۵-۱۷۱۹, Tehran, Iran
A Rashidi Mehrabadi - School of Water & Waste Water Engineering, College of Water Engineering, Power & Water University of Technology, P.O.Box ۱۶۷۶۵-۱۷۱۹, Tehran, Iran
M Fazeli - School of Water & Waste Water Engineering, College of Water Engineering, Power & Water University of Technology, P.O.Box ۱۶۷۶۵-۱۷۱۹, Tehran, Iran
H Khosrojerdi - School of Water & Waste Water Engineering, College of Water Engineering, Power & Water University of Technology, P.O.Box ۱۶۷۶۵-۱۷۱۹, Tehran, Iran

Increase in the population of urban societiesr, limitation of water resources, pollution caused by domestic and industrial waste water discharge to the environment and sewage refinery malfunction in decrease of effluents pollutant are the reasons that attracts researcher’s attention to the novel water resources and standardization of refinery effluents for non-domestic applications, besides of waste water treatment plant (WWTP) efficiency and control of bioenvironmental pollutant attentions. In this research for the first time aeration tank outflow in Ekbatan WWTP as a sample, was transferred to horizontal roughing filter (HRF) and parameters of TSS removal efficiency, sludge concentrating and coliforms removal efficiency in this unit was evaluated and compared with secondary settling tank. The pilot, which was used in this research, was designed with regard to previous studies of these filters in water industry and optimized them. Determination of waste water TSS removal efficiency that enters HRF and the efficiency of these filters were evaluated in overflow rates of 0.5, 1, 1.5 and 2 (m/hr). The mean removal performance in four experienced rates was calculated 99.25% with 0.4 standard deviation. The mean TSS of first fragment out flow in four rates was estimated 1960-5020 mgr/lit in range. By assessment of horizontal roughing filter function in total and fecal coliforms omission, the removal efficiency was more than 13log. Overally in this research HRF function in comparison with secondary sedimentation tank performance was acceptable and possibility of these reservoirs substitution with HRF needs complementary studies.

HRF, Secondary Settling Tank, Secondary Treatment, TSS Removal