Anoxic nitrification coupled to extracellular electron transfer

Research seeks alternative electron acceptors for nitrification to reduce energy usage. Carbon-based materials like natural organic matter (NOM) and graphene oxide (GO) are suggested. These act as electron acceptors, enabling anoxic nitrification via extracellular electron transport. Various consortia show potential for anoxic ammonium oxidation linked to NOM or GO reduction, constituting a significant portion of oxidized ammonium. Infrared spectroscopy verifies NOM's redox moieties reduction during anoxic nitrification. Tracer analysis using 15NH4+ and NOM indicates both NOM-driven anoxic nitrification and anammox. No 29N2 accumulation in NOM-absent settings confirms anoxic nitrification coupled to NOM microbial reduction.