Effects of Low-Concentration Perfluorooctane Sulfonate on Anaerobic Fermentation of Activated Sludge

• • PFOS at 4.5 μg/g TSS increased SCOD peak by ~28% over control after 14 days at 45 °C, enhancing biodegradable organic matter accumulation for downstream biogas production. • • NH4+-N concentration reached 358.73 mg/L on day 10 at 4.5 μg/g TSS, indicating altered nitrogen release dynamics with potential implications for nutrient recovery. • • PO43--P release was significantly suppressed: at day 14, concentration was 52.53 mg/L versus 111.5 mg/L in control, a 52.9% reduction, suggesting phosphorus immobilization or precipitation. • • 3D-EEM fluorescence intensity in Region I (aromatic proteins) increased by 56.0% (661.41 a.u. vs 424 a.u.) at 4.5 μg/g TSS, confirming enhanced solubilization of proteinaceous substrates.