Abstract
Gel fouling is a major rate-limiting factor for forward osmosis (FO) dewatering of waste activated sludge (WAS). This study proposes a novel FO system, assisted by in-situ ultraviolet/electrooxidation (UV/E-Cl) driven by dynamic reverse chloride ions (Cl(-)), for simultaneous WAS conditioning and dewatering. Superior filtration performances were achieved, with water flux reaching 614% of the control and filtration resistance reduced by orders of magnitude, primarily due to the targeted attack on protein and polysaccharide fractions within extracellular polymeric substances (EPS). Density functional theory (DFT) simulations identified that protein-polysaccharide interactions prefer a specific linear configuration, driving cross-linked network formation. Interfacial thermodynamics demonstrated that UV/E-Cl decreased foulant adhesion energy on the membrane surface by 97.51% through cleaving cross-links. Crucially, this work provides the quantitative thermodynamic evidence that shifts in water occurrence states surrounding network pores from bound to free water dominate gel fouling mitigation, with chemical potential variation accounting for 90.71% of filtration resistance.