Figure 4: Schematic overview of nitrogen conversions in the Olburgen PNA reactor.
From: Genome-based microbial ecology of anammox granules in a full-scale wastewater treatment system
Metabolites indicated in red, ammonium (NH4+), organic carbon (C-org) and molecular oxygen (O2) are supplied in the influent and through aeration/stirring, respectively. In the flocs and on the granule surface C-org is oxidized to carbon dioxide (CO2), which can be fixed by the autotrophs in the system. In the flocs and on the granule surface, NH4+ is oxidized to nitrite (NO2−). The formed NO2− is either reduced to nitric oxide (NO) or further oxidized to nitrate (NO3−). NO3− that is formed in the granules can be reduced again in the anaerobic core, either with C-org or molecular hydrogen (H2) as electron donor. H2 can be formed through fermentation of organic carbon by CHB2, and CFX1. This cyclic feeding will result in additional C-org removal from the system. NO formed from NO2− will be combined with NH4+ and converted to dinitrogen gas (N2) by AMX.
