Treatment of 2,4-DTBP containing wastewater by an ABR-MFC system at different HRTs: Performance, microbial community and metabolic pathway

2,4-Di-tert-butylphenol (2,4-DTBP) is a structurally stable emerging phenolic compound with notable environmental persistence, and its frequent detection in diverse aquatic environments has raised growing concerns. Thus, this study investigated the treatment performance of an anaerobic baffled reactor coupled with a microbial fuel cell (ABR-MFC) for 2,4-DTBP remediation, with a particular focus on elucidating the underlying mechanisms regarding pollutant degradation, microbial community succession, and metabolic pathway regulation driven by varying hydraulic retention times (HRTs). The results demonstrated that extending the HRT could enhance the removal of COD, NH 4 + -N and 2,4-DTBP, reaching 96.33%, 95.94% and 98.37% respectively. Two-dimensional infrared correlation spectroscopy revealed that prolonged HRT enhanced the substrate capture capacity of aerobic sludge by adjusting the conformation of polysaccharide chains (1080 cm −1 ). Metagenomic analysis revealed that when HRT was extended to 48 h, nitrogen-removal-related genera increased, enhancing the system's carbon and nitrogen metabolic capacity. In the aerobic compartments, dominant genera such as Betaproteobacteria (6.75%) and Burkholderiales (6.17%) might promote the initial degradation of 2,4-DTBP under short HRT (12 h) through their known aromatic ring hydroxylase activity. In the anaerobic compartment, the continuous increase in methanogenic pathways alongside. The core denitrification genes narG and nir attained relative abundances of 0.3269% and 0.1275% at 24 h HRT, respectively, representing increases of 22.8% and 58.9% compared to 12 h HRT, indicating that longer HRT achieved an optimal balance between 2,4-DTBP degradation and concurrent nitrogen removal. The experimental results offer novel insights into the effective treatment of wastewater contaminated with 2,4-DTBP.