MICROBIAL AND ENZYMATIC MECHANISMS IN INDUSTRIAL SLUDGE DEWATERING: EPS MODIFICATION AND KINETIC PERSPECTIVES

Abstract

Industrial sludge dewatering is challenging because of high moisture content and extracellular polymeric substances (EPS), which form hydrated matrices that retain water and hinder solid - liquid separation. Biological dewatering offers an alternative conditioning strategy by modifying these water-retaining structures through microbial activity and enzymatic hydrolysis. This review critically examines microbial processes and enzymatic strategies for improving industrial sludge dewaterability, with emphasis on microbial EPS degradation, microbial consortia, bio-drying, proteases, cellulases, amylases, lysozyme, and combined enzyme treatments. Microbial activity can progressively modify EPS through endogenous hydrolytic processes, whereas exogenous enzymes provide targeted degradation of protein- and carbohydrate-rich matrix components. These processes alter EPS composition, floc structure and water distribution, potentially increasing the fraction of water accessible to mechanical separation. Kinetic approaches are considered for describing EPS modification, enzymatic hydrolysis and biological moisture removal and for relating treatment time to measurable dewaterability. The review further examines reactor configurations, operational constraints, scale-up challenges and techno-economic and life-cycle considerations. Biological approaches remain constrained by slow reaction rates, mass-transfer resistance, enzyme instability, sludge heterogeneity and inhibition under high-salinity or toxic conditions. Integrated biological–mechanical systems and sludge-specific kinetic models are therefore needed for practical industrial application.