Removal of nitrogen from municipal wastewater by denitrification using a sulfur-based carrier: A pilot-scale study.

In the present study, to improve nitrate removal rate, a sulfur-based carrier was applied for autotrophic denitrification, and the removal rate was evaluated for advanced wastewater treatment without adding any external organic carbon source. Based on the results, an increased PAC concentration affected the removal efficiency of NO-N, and the optimal concentration of PAC was at 15 wt%. During the 60 d operation of a pilot process with a capacity of 1 m/d, the removal of T-N was 81.2% and 50.2% in reactors with and without sulfur-based carrier, respectively. The removal efficiency of NO-N exhibited a similar trend to that of T-N. According to the results, the removal of T-N and NO-N was noticeably enhanced to approximately 30% by adding a sulfur-based carrier to the AO pilot system. In addition, microbial community in both reactors was dominated by Thiobacillus, which is an autotrophic microorganism, displaying a dominant denitrification status. The present study compared the relative efficiencies of nitrate removal in AO pilot reactors with and without sulfur-based carriers for its successful application in real-scale autotrophic denitrification.