Tween 80 enhances n-hexane removal in a rotating drum biofilter by boosting bioavailability and microbial community resilience

n -Hexane, a recalcitrant hydrophobic volatile organic compound (VOC), exhibits low bioavailability that limits its biodegradation in engineered bioreactors. This study incorporated a non-ionic surfactant (i.e., Tween 80) into a rotating drum biofilter (RDB) to enhance its removal efficiency. Tween 80 significantly reduced surface tension (from 72 to 45.15 mN·m −1 ), enhanced gas-liquid mass transfer and increased n -hexane removal efficiency from 42.93% to 87.83% (elimination capacity from 3.4 to 31.62 g·m −3 ·h −1 ). High-throughput sequencing revealed that Tween 80 shaped a resilient community structure across operational phases, the microbial community was dominated by Actinobacteria and Proteobacteria . At the genus level, Mycobacterium remained the dominant alkane degrader (>57%), maintaining degradation capacity even under substrate stress. Molecular ecological network analysis showed that ecosystem stability relied not only on dominant taxa but also on keystone genus with strong interaction capacity, including Bacillus , Nocardia , Microbacterium , Enterobacter , and Chujaibacter . Their presence indicates robust functional redundancy and interaction-based resilience, enabling rapid restoration of degradation performance once n -hexane a n d Tween 80 were resupplied. Overall, Tween 80 enhanced n -hexane biodegradation through two synergistic pathways: improving hydrophobic-substrate bioavailability and strengthening the ecological resilience of the microbial consortium by supporting functional persistence, cooperative metabolism, and rapid recovery. These findings provide a resilience-oriented mechanistic basis for optimizing surfactant-assisted RDB systems treating hydrophobic VOCs.