The Promotion of the Polycyclic Aromatic Hydrocarbons Degradation Mechanism by Humic Acid as Electron Mediator in a Sediment Microbial Electrochemical System

In this study, polycyclic aromatic hydrocarbons (PAHs) in sediments were efficiently removed using humic acid as an electron mediator in a sediment microbial electrochemical system. The results indicated that with the addition of humic acids, the removal efficiencies of naphthalene, phenanthrene, and pyrene for areas distant from the anode increased by 45.91%, 97.83%, and 85.56%, respectively, compared to the control group. Analysis of microbial community structure and function revealed that the addition of electron mediators did not significantly alter the microbial community structure or the corresponding functional expression in the anode and sediment. Changes in the form of humic acid were investigated, revealing that humic acid expanded the range of electron transfer in the sediment through the redox processes of quinone and semiquinone groups. Combined with the analysis of metabolic products, the mechanism by which microbial electrochemical action promotes the degradation of PAHs in sediments was elucidated.