en تخصصي Special Original articles <div dir="ltr" style="text-align: justify;"><strong><em><span style="font-size:10.0pt;">Introduction:</span></em></strong><span style="font-size:10.0pt;"> Sequential batch reactor (SBR) is one of the modified biological treatment systems which is able to remove BOD₅, Nitrogen, and phosphorus from wastewater. The object of this study is to determine the removal efficiency of nitrogen, phosphorus, and heavy metals from municipal wastewater by the advanced SBR system.</span><br> <strong><em><span style="font-size:10.0pt;">Materials and Methods:</span></em></strong><span style="font-size:10.0pt;"> This descriptive-analytical and cross-sectional study was conducted on advanced SBR in Yazd city wastewater treatment plant during a one-year period (from September, 2014 until August, 2015). The samples were collected from the influent and effluent of the advanced SBR as a composite in order to measure BOD₅, TKN, NH₄⁺, TP parameters, and heavy metals monthly. Also, statistical t-test was used to compare heavy metals quantities with standard ones.</span><br> <strong><em><span style="font-size:10.0pt;">Results:</span></em></strong><span style="font-size:10.0pt;"> The results showed that the mean of removal efficiency of BOD₅, TKN, NH₄⁺, and TP were 92.24, 80.36, 90.41, and 66.41 percent, respectively. Also, the removal efficiency of Iron (Fe), Plum bum (Pb), Nickel (Ni), Zink (Zn), Chromium (Cr), and Cadmium (Cd) were 47.77 %, 40.71 %, 24.79 %, 12.29 %, 5.70 % and 5.65 %, respectively.</span><br> <strong><em><span style="font-family:calibri,sans-serif;"><span style="font-size:10.0pt;">Conclusion:</span></span></em></strong><span style="font-family:calibri,sans-serif;"><span style="font-size:10.0pt;"> The high removal efficiency of BOD₅, TKN, and NH₄⁺ showed that this advanced SBR system had an appropriate efficiency for nitrification. Phosphorus removal (TP) had a lower efficiency than those of NH₄⁺ and TKN, but it was within the environmental standard limits. On the other hand, in the advanced SBR the removal efficiency of heavy metals for Cd was not within the standard limits.</span></span></div> Wastewater,Nitrogen,Phosphorus,Heavy Metal 117 125 http://jehsd.ssu.ac.ir/browse.php?a_code=A-10-1-45&slc_lang=en&sid=1 Seyed Vahid Ghelmani No Islamic Azad University, Yazd, Iran. Seyed Abolghasem Mirhosseni Dehabadi mirhosseinid@yahoo.com Yes Environmental Pollutions Department, Islamic Azad University, Yazd, Iran. Mohammad Taghi Ghaneian No Environmental Science and Technology Research Center, Department of Environmental Health Engineering, School of Public Health, Shahid Sadoughi University of Medical Science, Yazd, Iran. Hadi Eslami No Environmental Science and Technology Research Center, Department of Environmental Health Engineering, School of Public Health, Shahid Sadoughi University of Medical Science, Yazd, Iran.