[Impact of C/N Ratio on Nitrogen Removal Performance and N₂O Release of Granular Sludge CANON Reactor]

To Explore a suitable C/N ratio for efficient nitrogen removal and simultaneously achieving N₂O release reduction, ammonia-rich wastewater with sodium acetate as an organic carbon source in a granular sludge completely autotrophic nitrogen removal over nitrite (CANON) reactor under different C/N water conditions were studied to determine the reactor's nitrogen removal performance and N₂O release. The results showed that the total nitrogen (TN) removal rate and the removal load tended to increase gradually with the increase of C/N, ranging from 0 to 2.0. When C/N=0, the TN removal rate was 56.50 mg·L^-1 in 7 h; the highest TN removal efficiency was 49%. When C/N=2.0, the highest TN removal rate was 71.42 mg·L^-1 in 7 h; the highest TN removal efficiency was 59.52%, and the contribution of CANON to nitrogen removal gradually decreased, whereas the denitrification contribution gradually increased. When △NO₃^--N/△TN=0.086, the contribution of CANON nitrogen removal was only 51.48% and that of denitrification was 48.52%. The N₂O release volume and release ratio decreased with increasing C/N. When C/N=0, the N₂O release volume and rate were the highest, namely 3.60 mg and 2.13%, respectively. The lowest N₂O release volume and rate were 1.61 mg and 0.75%, respectively, when C/N=2.0.