Anoxic nitrification with carbon-based materials as terminal electron acceptors.

Area of Science:

• Environmental Microbiology
• Environmental Chemistry
• Wastewater Treatment Technologies

Background:

• Nitrification is crucial for wastewater treatment but typically requires oxygen.
• Developing anoxic nitrification methods is essential for energy-efficient treatment.
• Extracellular electron acceptors (EEA) are being explored to sustain microbial processes.

Purpose of the Study:

• To investigate humic substances (HS) and graphene oxide (GO) as novel EEAs for anoxic nitrification.
• To explore sustainable alternatives for maintaining nitrification in wastewater treatment.
• To identify microbial communities involved in this novel anoxic process.

Main Methods:

• Incubation experiments using anaerobic microbial consortia with HS or GO.
• Ammonium conversion and nitrate production measurements.
• Electron balance calculations, 15N tracer analysis, and phylogenetic analysis.

Main Results:

• Up to 87% conversion of ammonium to nitrate was achieved, coupled with HS or GO reduction.
• Electron balance confirmed HS and GO participation in ammonium oxidation.
• Phylogenetic analysis indicated Firmicutes, Euryarchaeota, and Chloroflexi involvement.

Conclusions:

• Humic substances and graphene oxide effectively serve as EEAs for anoxic nitrification.
• This process offers a new avenue for ammonium oxidation in anaerobic environments.
• Potential applications include bioelectrochemical systems utilizing carbon-based anodes.