Enhancement of Performance Robustness and Nitrogen Removal by Coupling Anammox with Denitrification in a Corncob-Dosed Reactor

Biofilm carriers play an important role in attached growth systems for wastewater treatment processes. In this study, to establish a more robust and efficient anammox system, corncobs were used as biofilm carriers in the anammox process to tackle nitrite inhibition and enhance nitrogen removal. Results indicated that the nitrite- and nitrate-denitrifying activities of the corncob biofilm were 32% and 26%, respectively, higher than that of bulk sludge when adopting synthetic wastewater as influent that only contained NH4+-N and NO2−-N. The higher nitrite-denitrifying activity of the corncob biofilm had a positive effect on alleviation of nitrite inhibition. Furthermore, the corncob anammox system reached ∼92.5% total nitrogen (TN) removal stably, and the anammox pathway played a dominant role by carrying out more than 90% of TN removal. Anammox bacteria coexisted stably with the denitrifiers in the corncob biofilm, in which the anammox activity and denitrifying activity were 42.46 ± 0.58 mg NH4+-N d−1 and 10.28 ± 0.02 mg NO3−-N d−1, respectively. Therefore, employing corncobs as biofilm carriers was a useful and applicable supplement for enhancing the performance robustness of the anammox process.