Related Experiment Video
Updated: May 22, 2026

Measurement of the Potential Rates of Dissimilatory Nitrate Reduction to Ammonium Based on 14NH4+/15NH4+ Analyses via Sequential Conversion to N2O
Published on: October 7, 2020
Influence of free ammonia on completely autotrophic nitrogen removal over nitrite (CANON) process
Shan Li1, You-Peng Chen, Chun Li
1Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment of MOE, Chongqing University, China.
Abstract:
Free ammonia (FA) plays a significant role in the stable, long-term, completely autotrophic nitrogen removal over nitrite (CANON) system operation. The influence of FA on the CANON process in a sequencing batch biofilm reactor was explored. Under controlled FA concentrations of 5.0 mg L(-1) to 10.0 mg L(-1), nitrite-oxidizing bacteria (NOB) was inhibited and achieved partial nitrification, which was important for a successful and quick start-up of the CANON process from activated sludge. However, NOB was acclimated to the condition after the process start-up. Ammonia-oxidizing bacteria (AOB) and anaerobic ammonium-oxidizing bacteria (AnAOB) activities were unaffected when FA concentration was increased from 10 mg L(-1) to 17 mg L(-1), but NOB was completely inhibited only for a short time. The AOB and AnAOB activities were inhibited and the CANON system was deteriorated when FA concentration reached 30 mg L(-1) to 32.5 mg L(-1) at pH 8.5, whereas NOB activity was unaffected. Correlation analysis showed that FA concentration higher than 20 mg L(-1) resulted in the deterioration of the system.
Related Concept Videos
Inorganic Nitrogen Assimilation
Overview of Nitrogen Metabolism
The largest pool of nitrogen available in the terrestrial ecosystem is gaseous nitrogen (N2) from the air, but this nitrogen...
Metabolism of Chemolithotrophs
The Nitrogen Cycle
2° Amines to N-Nitrosamines: Reaction with NaNO2
Free Energy Changes for Nonstandard States

