Removal Efficiency of Nitrogen, Phosphorus and Heavy Metal by Intermittent Cycle Extended Aeration System from Municipal Wastewater (Yazd-ICEAS)

Introduction: 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. Materials and Methods: 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. Results: 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. Conclusion: 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.