Influence of Biological Activated Carbon on Simultaneous Nitrification and Denitrification in Inflow with Different C/N Ratios

: Influence of biological activated carbon (BAC) on simultaneous nitrification and denitrification (SND) in inflow with different C/N ratios was investigated with continuous operation of BAC reactor and SBR. Methanol was added as carbon source and the inflow C/N ratio was set to 3, 5, 8 and 10 to run for about 120 cycles, under conditions of indoor temperature (15-27℃), initial DO 2-3mg·L-1. The TN removal efficiency and stability of two reactors were compared. The results showed that, BAC reactor had a higher TN removal efficiency than SBR at different C/N ratios. TN removal rate of BAC reactor was 44.88%, 58.07% and 66.64%, when the C/N ratio was 3, 5 and 8 respectively. After increasing the C/N ratio to 10, the BAC reactor could maintain TN removal rate of 63.65%, but the SBR showed sludge bulking. BAC provided various DO environments for microorganisms in a vessel, which was beneficial to SND. BAC could reduce the influence of excessive carbon source on the nitrification system, enlarge the application range and improve the stability of reactor at different C/N ratios, and increase the nitrogen removal capacity of organic matter. BAC provided condition for efficient nitrogen removal.