Integrated sludge resources hierarchical recovery: enhancing VFAs production through pilot scale liquid-state anaerobic fermentation by sludge residues-based biochar - Jing Zhang; Dong-Shan Yang; Jia-Yu Yang; Yun-Yi Song; Nan Wu; Tian Pu; Ge Zhu; Hong-Bo Liu; He Liu (Bioresource Technology, 2026)