Effect of salinity in wastewater on solid phase products of hydrothermal carbonization of organic solid wastes

NaCl and MgSO 4 are selected as the representative substances to appraise the impact of varying salinity levels on the physicochemical properties of hydrochar obtained from chicken manure (CM), corn stover (CS), and their mixture. Results indicate that salinity in the water source significantly affects the degradation, condensation, and aggregation mechanisms of the organic wastes. In the presence of MgSO 4 in the wastewater, the fixation of alkali metal salts in both the feed and the water source obstructs the hydrolysis of the feed as well as the polycondensation reaction of its degradation products, leading to hydrochar with high yield but low higher heating value (HHV). Conversely, NaCl in the water source promotes feed hydrolysis and the formation of secondary carbon, thereby elevating the HHV of the hydrochar obtained. Moreover, the hydrochar generated under NaCl water conditions demonstrates a higher degree of aromatization.