Factors influencing the start-up and stability of partial nitrification in a continuous flow reactor

The start-up and stability of partial nitrification in a continuous flow bioreactor was investigated in this study. Nitrogen loading rate (NLR) was set to be the central examined factor and partial nitrification performance of AO system was monitored with its variation. Results from experiments indicated that NLR was the most direct factor leading to nitrite accumulation, and inhibition of free ammonia (FA) and free nitrite acid (FNA) had significant effect on partial nitrification. The gap between the specific growth rate of ammonia-oxidizing bacteria (AOB) and that of nitrite-oxidizing bacteria (NOB) leads to the AOB enrich and NOB eliminate in the system fed by high ammonia concentration inflow.