This study was focused on improving nitrification efficiencies of M-dephanox (Modified-Dephanox) process. Rotating biological contactor was used instead of floating sponge type media in nitrification reactor. High ammonia removal efficiencies were observed in nitrification reactor regardless of organic loading from contactor of M-dephanox process. Denitrification efficiencies were also increased to maintain low NO₃-N concentration in effluent. This enhanced phosphate release in anaerobic contactor and resulted in high removal efficiencies of phosphorus. Average removal efficiencies of TCOD_Cr and SCOD_Cr were 93.8% and 81.6% respectively while those of TKN and NH₄+^-N were 80.9% and 74.4% respectively. As for phosphorous treatment the average removal efficiencies of TP and OP were 94.7% and 94.3% respectively. Also effect of operating temperature on nitrogen removal was examined. Average removal efficiency of TN was 65.8 % at 15℃ or below (at average temperature of 13.3℃) while that was 82.8% at 15℃ or above (at average temperature of 21.9℃).