Abstract
Abstract
In this study, a three-stage biological aerated filter (BAF) system was proposed to enhance nitrogen removal in the treatment of low carbon-to-nitrogen ratio (C/N ratio) municipal wastewater. Laboratory experiments were conducted at three different recirculation ratios of 1, 2, and 3. Effects of dynamic flow were also evaluated in this study. Results of the long-term operation of the three-stage BAF system in dynamic flow showed nitrogen removal was affected by the both recirculation ratio and C/N ratio in dynamic flow. Dynamic flow enabled the nitrogen removal efficiency of the system to be higher than that of nondynamic flow system in treating low C/N ratio wastewater due to the more efficient use of organic substrates. Overall NH4-N removal performance was stable with a removal efficiency of 99% on average during the operational period due to the unique system configuration where independent nitrification occurred. It was concluded that the three-stage BAF system proposed in this study provided excellent performance in the removal of nitrogen by employing dynamic flow and three columns functioning as sorption, denitrification, and nitrification, respectively.