en Environmental Health Environmental Health پژوهشي Original Article <table align="left" cellpadding="0" cellspacing="0" hspace="0" vspace="0"> <tbody> <tr> <td align="left"><strong>Background & Aims of the Study:</strong> Wastewater discharges from vegetable oil industry cause environmental problem, including pollution of groundwater and surface water. Therefore, this study evaluated the efficiency of Integrated Fixed-Film Activated Sludge (IFAS) reactor for treatment of wastewater from Varamin vegetable oil industries.<br> <strong>Materials & Methods:</strong> This was an experimental study. The anaerobic reactor and the aerobic reactor with sedimentation unit were made from polyethylene and plexiglas. The IFAS reactor was packed with ratio 70% by Honeycomb packing F 19-1. To create optimal growth conditions for microorganisms in anaerobic digestion, the COD/N/P ratio was adjusted to 300/5/1. Sampling and analysis of the total of the parameters studied at the system stability time during different times from the pilot output.<br> <strong>Results:</strong> The results showed the high removal efficiency of the COD, BOD and TSS (97.9%, 98.2% and 98.8 %, for 2 day anaerobic and 8 hrs aerobic, respectively). Also, the highest COD removal efficiency was observed for these three parameters in the IFAS system at HRT 8 hrs aerobic (>99.7%, >97.7% and 97.6 %, respectively).</td> </tr> </tbody> </table> <div style="clear:both;"></div><strong>Conclusion:</strong> In general, the results showed that industrial wastewater treatment methods using the IFAS biological reactor are a suitable method for the removal of pollutants and can replace conventional methods. Also, the efficiency of removing COD, BOD and TSS from plant effluent has been at the optimum level for all retention time managed by the IFAS system. Integrated Fixed-Film Activated Sludge, Attached Growth, Industrial Wastewater, Vegetable Oil Industry, Biological Treatment. 192 199 http://jhygiene.muq.ac.ir/browse.php?a_code=A-10-174-1&slc_lang=en&sid=1 Ghazaleh Monazami Tehrani ms.mahmudi65@gmail.com 0000-0002-8022-2679 No Department of Health, Safety and Environment, school of public health and safety, Shahid Beheshti University of Medical Scien ces and Health Services Mohammad Molla Mahmoudi ms.mahmudi65@gmail.com 0000-0002-6382-0327 No Department of Environmental Health Engineering, School of Public Health, Hamadan University of Medical Sciences, Hasti Borgheipour ms.mahmudi65@gmail.com 0000-0002-0337-6850 Yes Department of Environmental Engineering, Central Tehran Branch, Islamic Azad University Alireza Nezampour ms.mahmudi65@gmail.com 0000-0001-5012-638X No D epartment of Health, Safety, and Environment, S chool of Engineering, Islamic Azad University, Central Tehran Branch