Electrochemical performance and response of bacterial community during phenanthrene degradation in single-chamber air-cathode microbial fuel cells

Polycyclic aromatic hydrocarbons have attracted considerable attention for their carcinogenic, teratogenic, and mutagenic properties in humans. Phenanthrene is one of the most abundant polycyclic aromatic hydrocarbons in aquatic environments. In this study, different concentrations of phenanthrene were degraded by single-chamber air-cathode microbial fuel cells. The electrochemical parameter of microbial fuel cells and biofilm changes on the anode were observed. The results showed that the addition of phenanthrene reduced the power output of the microbial fuel cell which affected the process of microbial electricity generation. Meanwhile, microorganisms destroyed the original structure of phenanthrene through anaerobic metabolism, and achieved good average degradation of 94.9-98.4%. Observation of the anodic biofilm found that the microbes had tolerance to phenanthrene and the biofilm exhibited to be well-constructed. Bacterial community distribution showed a decrease in the relative abundance of Acidovorax and Aquamicrobium, whereas the relative content of the main electroactive organism, Geobacter, increased by a factor of three. The results show that it is feasible for microbial fuel cells to biodegrade phenanthrene, and provide some references for the changes of microbial community during degradation process.