Degradation of polycyclic aromatic hydrocarbons (PAHs) in textile dyeing sludge with ultrasound and Fenton processes: Effect of system parameters and synergistic effect study.

•Ultrasound–Fenton process can degrade PAHs in the surface and interior of sludge.•The degradation of HMW PAHs was close to or even higher than those of LMW PAHs.•The disruption of sludge would increase the amount of PAHs in the reaction system.•The degradation efficiency of PAHs would be inhibited by organic matter.