Electrode-Driven Nitrogen Conversion in Bioelectrochemical Systems: Mechanisms, Advances, and Perspectives

Abstract

Extracellular electron transfer (EET) mediates the microbial conversion of diverse nitrogen species and makes the possible application of a bioelectrochemical system (BES) to remediate the environment and recover resources. Electrodes are the sole electron donor and acceptor of BES for driving nitrate reduction, ammonia oxidation, and nitrogen fixation. Previous findings in this topic advance our understanding of microbial metabolism, EET mechanisms, and factors influencing the performance of BES for nitrogen species conversion. The electrode-driven ammonia oxidation to nitrogen performs the conversion rates ranging from 1 mg/L/d to 151 mg/L/ d and the rates range from 3 mg/L/d to 81 mg/L/d when the nitrate/nitrite as the products. The rate for nitrate reduction driven by biocathode can be from 0.34 mg/L/d to 192 mg/L/d as the different electrode materials are used. This review highlights the mechanisms of electrodes driving the microbial conversion of diverse nitrogen species in BES and the performance is summarized. In addition, the challenges and outlooks are identified for future research on this topic. Future research should aim to uncover novel electroactive microorganisms and optimize system configurations to enhance nitrogen conversion efficiency. These advances will be critical for scaling up BES applications in environmental remediation and sustainable resource recovery.