Abstract
This study was initiated to evaluate a proposed A2/O-BAF system, in which a biological aerated filter (BAF) system was incorporated into a A2/O system, by comparing it with the conventional A2/O system. The evaluation was mainly focused on the nitrogen removal. Long term lab-scale experimental results presented that the $NH_4-N$ removal of the A2/O-BAF system was 60.2 and 34.8% higher than that of the conventional A2/O system at the hydraulic retention time (HRT) of 6 and 4 h, respectively, and the similar tendency was observed in the TCOD and SCOD removal. These results would be attributable to the additional BAF installation in the conventional A2/O process. The untreated $NH_4-N$ in A2/O system were effectively removed in the BAF reactor. Specifically, it was revealed that the BAF reactor exerted much more ability in treating $NH_4-N$ at short HRT. Consequently, it is believed that the proposed A2/O-BAF system could be effectively applied to the wastewater treatment at short HRT and even in winter season for the removal of nitrogen.