Characteristics analysis of char from sewage sludge pyrolysis: Char properties, combustion behavior and ash fusion

The utilization of sewage sludge (SS) is often restricted due to its high-moisture content, while the pyrolysis process of SS could generate a valuable sludge char (SC) product. This work investigated the physicochemical properties, combustion performance and ash fusion characteristics of SC produced at the different pyrolysis temperatures. The results showed that higher pyrolysis temperature significantly increased the specific surface area and porosity of SC, with stable microstructures and excellent high-temperature performance. The X-ray diffractometer (XRD) analysis revealed the decomposition of low-melting minerals and formation of high-melting minerals in SC ash, leading to improved ash fusion resistance. Adding 20 % SC obtained at 700°C into corn stover (CS) achieved the highest flow temperature improvement in this study. These findings provide insights into optimizing pyrolysis process of SS and enhancing the potential applications of SC in industrial energy utilization and environmental remediation.