Digested sludge (DS) is a valuable matrix that still holds potential for energy and nutrient recovery. This study explored the application of low-frequency ultrasound (US) treatment of DS to enhance organic matter solubilization and Polycyclic Aromatic Hydrocarbons (PAHs) transfer while reducing energy losses on already biodegradable substances. US treatment significantly increased solubilization, enhancing the specific methane production (SMP) by 51%. It also mobilized PAHs into the liquid phase. Preliminary BMP tests showed an improvement in the removal of target compounds, highlighting US as a promising method for improving DS biodegradability and quality.