Reconstructing sludge microstructure for deep dewatering: A critical review of mechanisms and prospects of skeleton construction technology.

The rapid urbanization has led to a dramatic increase in sludge production, whose treatment is further complicated by high moisture content and hazardous substances, resulting in elevated operational costs. Due to the compressibility and hydrophilicity of sludge, mechanical filter press operations would lead to pore clogging, resulting in poor performance of conventional mechanical dewatering techniques. Skeleton construction technology (SCT) emerges as a promising solution, where the incorporation of rigid materials optimizes sludge cake structure, reduces compressibility, and enhances permeability. In this review, recent advances in sludge deep dewatering through SCT were critically summarized. The mechanisms of physical support and pore reconstruction enabled by SCT were analyzed, with comparative evaluation of organic and inorganic skeleton construction agents in terms of dewatering performance, cost, and environmental impact. Furthermore, combined dewatering technologies integrating SCT with flocculation, electro-dewatering, and other technologies were investigated. The potential applications of SCT in sludge treatment and disposal were systematically evaluated. Future research directions, including machine learning optimization and life cycle framework in SCT applications were innovatively introduced. This review presents critical analysis and practical perspectives to advance the development of efficient and sustainable sludge treatment technologies.