Study on Nitrogen Removal by Aerobic Denitrifying Bacteria Enhanced by Iron-Anode Pulsed Electric Field: Denitrification Performance, Metabolic Pathways and Electron Transfer Process

Abstract

Recently, aerobic denitrification technology has gradually become a research hotspot in the field of biological nitrogen removal based on its unique advantages. However, there are still problems such as easy loss of aerobic denitrifying bacteria, poor competitiveness and difficulty in forming advantageous flora. Therefore, an iron anode pulsed electric field (PEF-Fe) is constructed as a means of enhancing aerobic denitrification process, through improving the productivity of aerobic denitrifying bacteria, achieving the purpose of strengthening the biological denitrification and satisfying the long-term demand of biological denitrification of wastewater treatment. Firstly, the one-way analysis and response surface methodology (RSM) model are utilized to determine the optimal process parameters for strain W207-14 growth and metabolism. Secondly, the effects of different reaction systems on the growth and metabolism of strain W207-14 are compared to determine the optimal treatment system. Finally, the mechanism of action and metabolic pathways of PEF-Fe-enhanced strain W207-14 are investigated from the molecular biology level, with a particular focus on carbon and nitrogen metabolic pathways, and electron transfer processes during aerobic respiration. It was found that PEF-Fe enhancement can promote the growth of the strain, alter metabolic pathway, and lead to the up-regulation of gene expression in the metabolic pathway. Consequently, an in-depth study of the mechanism of action of PEF-Fe treatment will help to develop more efficient microbial treatment technologies.

Keywords: aerobic denitrifying, electron transfer process, Metabolic pathways, iron-anode pulsed electric field.