Hydrothermal carbonization of sewage sludge: Catalytic effect of Cl− on hydrochars physicochemical properties

Abstract

Abstract In order to analyze the influence of disruption extracellular polymeric substances (EPS) and cell wall on the hydrothermal carbonization (HTC) of sewage sludge (SS), ultrasonic pretreatment was selected to dispose. According to solid phase and aqueous phase analysis results, it indicated that ultrasonic pretreatment can effectively break the EPS and cell wall structure, resulting in hydrolysis, dehydration and decarboxylation enhancing during HTC. The role of free radical increased elemental content in hydrochar. NaCl, which promoted hydrolysis, dehydration and decarboxylation, affected on the “real” hydrochar properties for it can be adsorbed in the surface of hydrochar. Disruption EPS structure and enhancing hydrolysis were key steps to HTC of SS, which would influence solid and liquid phase properties. The results would give more help to understand HTC process and dispose to other organic waste.