Enhancing the Efficiency of Sludge Dewatering via EPS Regulation: A Low-Temperature, Thermally Assisted Peroxymonosulfate–Tannic Acid Conditioning Strategy

Large quantities of sludge are produced during municipal and industrial wastewater treatment. To achieve advanced treatment of sludge containing multiple hazardous substances, the dewatering stage is of paramount importance. This study developed a novel, low-temperature, thermally assisted (55 °C) peroxymonosulfate (PMS)–tannic acid (TA) sequential conditioning strategy to improve sludge dewaterability. The combined treatment significantly enhanced dewatering performance, reducing sludge cake water content from 88.81% to 74.60% and decreasing capillary suction time by 67.20%. Systematic investigations revealed that low-temperature, thermally assisted PMS oxidation effectively disrupted extracellular polymeric substances (EPS), while subsequent TA complexation optimized floc structure and improved hydrophobicity. The 55 °C operating temperature demonstrated superior efficiency compared to conventional high-temperature processes, providing an energy-saving alternative for sludge conditioning. Mechanistic studies through 3D-EEM and FT-IR analyses elucidated the critical role of protein/polysaccharide transformation in EPS during the conditioning process. This study presents a novel, energy-efficient pretreatment approach for advanced sludge treatment, offering significant implications for promoting sludge reduction and resource recovery.