Magnetic MnFe2O4 modified sludge biochar for peroxymonosulfate activation to enhance deep dewatering of excess sludge: Performance and synergistic mechanism - Jinyun Guan; Kai Cheng; Cong Zhang; Yihang Sun; Yichenyang Li; Chong Li; Jifeng Guo (Process Safety and Environmental Protection, 2026)