Kinetics, diffusional limitation and microscale distribution of chemistry and organisms in a CANON reactor

Abstract
In the Completely Autotrophic Nitrogen removal Over Nitrite (CANON) process, aerobic and anaerobic ammonia oxidizing bacteria cooperate to remove ammonia in one oxygen-limited reactor. Kinetic studies, microsensor analysis, and fluorescence in situ hybridization on CANON biomass showed a partial differentiation of processes and organisms within and among aggregates. Under normal oxygen-limited conditions (∼5 μM O2), aerobic ammonia oxidation (nitrification) was restricted to an outer shell (500 μm) accounted for 68% of the anammox potential whereas 65% of the nitrification potential was found in the smaller aggregates (2 microsensors showed that the thickness of the activity zones varied as a function of bulk O2 and NO2 concentrations and flow rate.