Hydrothermal Treatment of Municipal Sewage Sludge for Pathogen Inactivation and Dewaterability Enhancement

Abstract

Municipal sewage sludge management remains a significant environmental and operational challenge due to the presence of pathogenic microorganisms, high moisture content, and complex organic contaminants. The present study investigates the hydrothermal treatment of municipal sewage sludge for pathogen inactivation and enhancement of sludge dewaterability under controlled processing conditions. The research focuses on evaluating the influence of treatment temperature, residence time, pressure, and solids concentration on microbial destruction efficiency, sludge physicochemical properties, and water removal performance. Experimental analysis demonstrates that hydrothermal treatment effectively disrupts microbial cell structures and organic matrices, resulting in substantial pathogen reduction and improved sludge stabilization. Results indicate that elevated treatment temperatures significantly enhance the inactivation of bacteria and other pathogenic organisms while simultaneously promoting hydrolysis and breakdown of extracellular polymeric substances responsible for water retention in sludge. The study further reveals that optimized hydrothermal conditions improve sludge dewaterability through particle restructuring and reduction of bound water content, thereby decreasing filtration resistance and improving mechanical dewatering efficiency. Comparative assessment with conventional sludge conditioning and thermal treatment methods confirms the advantages of hydrothermal processing, including reduced chemical demand, lower sludge volume, and improved biosolids handling characteristics. In addition, the treated sludge exhibits potential suitability for subsequent resource recovery and beneficial reuse applications.