Abstract
In this study, the removal of heavy metals from char derived from gasification of hydrothermally carbonized (HTC) sewage sludge was investigated. The resulting hydrochar was gasified, producing a char with potential agricultural applications after impregnation with MgCl₂ and CaCl₂. The novelty of this approach lies in utilizing gasification char from HTC-treated sludge, rather than the sludge itself. While previous studies have directly applied sewage sludge for heavy metal removal, this work focuses on the valorization of char. Significant amounts of heavy metals were successfully removed via chlorination, enhancing the char’s suitability for agricultural reuse. Preliminary results indicated that magnesium chloride was more effective than calcium chloride in removing heavy metals. Furthermore, this process shifts the paradigm from mere waste disposal to an integrated strategy for industrial scale reuse. The application of char from waste also contributes to environmental relief by reducing landfill disposal and promoting resource circularity. Future research should aim to refine chlorination conditions, evaluate long-term effects in diverse agricultural contexts, and define practical strategies for industrial-scale implementation.