Partial nitritation performance and microbial community in sequencing batch biofilm reactor filled with zeolite under organics oppression and its recovery strategy

Abstract Influences of organics on partial nitritation performance were investigated in a lab-scale sequencing batch biofilm reactor filled with zeolite. Significant differences in nitrite production rate (NPR) were observed between different dosages of glucose. With influent COD/N ratio from 0 to 1.5, NPR declined from 0.4 to 0.05 kg/(m3·d). Meanwhile, an appropriate NO2−-N/NH4+-N ratio (1.4 ± 0.5) could be obtained for simultaneous anammox denitrification at COD/N ratio of 0.5. Increasing airflow rate was found as an effective recovery strategy. Other than competition of heterotrophs with nitrifiers for dissolved oxygen, it has been verified that addition of organics generated higher free ammonia, and then further inhibited ammonium oxidizing bacteria (AOB). Moreover, three-dimensional excitation-emission matrix (3D-EEM) results revealed that protein-like and humic acid-like substances were the main components in extracellular polymeric substances (EPS). And high-throughput sequencing analysis demonstrated that the relative abundance of AOB decreased.