en عمومى General مقاله اصیل Original Article <p>Background: The effective size of the end grain of horizontal roughing filters (HRFs) is larger than 2 mm. This study aimed to examine the efficiency of HRFs in removing nitrate, phosphate, and chemical oxygen demand (COD) from effluent of a wastewater stabilization pond. Methods: This experimental study was conducted in 2013. The pilot project was transferred to the Karaj wastewater treatment plant (stabilization pond), and the installation, equipping, and start-up of the system began using an effluent treatment plant. Sampling was done from March to August in 3 rates, 0.5, 1 and 1.5 m/h, and included simultaneous sampling from inlet and outlet filtering to determine the concentrations of nitrate, phosphate, and COD. Results: At filtration rates of 0.5, 1, and 1.5 m/h, the average nitrate removal equaled 25%, 32%, and 34%, respectively, average phosphate removal equaled 29%, 26%, and 28%, respectively, and the average COD removal at filtration rates of 0.5, 1, and 1.5 m/h equaled 62%, 66%, and 68%, respectively. Outlet values of phosphate and nitrate were lower than the standards set by the Environmental Standards Organization (ESO) (P < 0.05). Conclusion: According to the results of this study, the HRF function was approximately adequate in COD removal, but its efficiency in nitrate and phosphate removal was lower.</p> Wastewater stabilization pond, Horizontal roughing filter, Nitrate, Phosphate, Chemical oxygen demand 87 92 http://ehemj.com/browse.php?a_code=A-10-27-16&slc_lang=en&sid=1 Seyed Mostafa Khezri 10031947532846008461 10031947532846008461 No Department of Environmental Engineering, School of Environment and Energy, Science and Research Branch, Islamic Azad University, Tehran, Iran Majid Gharibi 10031947532846008462 10031947532846008462 No Environmental Health Engineering, School of Public Health, Qom University of Medical Sciences, Qom, Iran Hossein Jafari Mansoorian 10031947532846008463 10031947532846008463 No Environmental Health Engineering Research Center, Department of Environmental Health, Kerman University of Medical Sciences, Kerman, Iran Mohsen Ansari 10031947532846008464 10031947532846008464 No Environmental Health Engineering, School of Public Health, Qom University of Medical Sciences, Qom, Iran Farideh Atabi 10031947532846008465 10031947532846008465 No Department of Environmental Engineering, School of Environment and Energy, Science and Research Branch, Islamic Azad University, Tehran, Iran Taha Tohidi Mogaddam 10031947532846008466 10031947532846008466 No Environmental Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran Nahid Rashtchi nahidrashtchi1392@gmail.com 10031947532846008467 10031947532846008467 Yes Environmental Engineering–Water and Wastewater, Islamic Azad University, Western Tehran Branch, Tehran, Iran