Critical review of reactivating spent activated carbon for sustainable waste management

Spent activated carbon (SAC) disposal presents economic and environmental challenges, including resource depletion, waste generation, and potential environmental contamination. Reactivation offers a sustainable approach to restoring adsorption capacity while reducing operational costs and supporting circular economy principles. This review critically examines thermal and chemical reactivation technologies, focusing on their effectiveness, energy requirements, carbon recovery, and industrial applicability. Key challenges include inconsistent regeneration performance, structural degradation, residual chemical contamination, and difficulties in treating mixed SAC feedstocks. Attention is given to process design, simulation, scale‐up, and the optimization of Multiple Hearth Furnaces (MHF), which are widely used for industrial thermal reactivation. The limited availability of systematic studies on MHF operating conditions, energy efficiency, and carbon recovery highlights important research gaps. This review identifies technological and operational strategies for improving reactivation performance, reducing environmental impacts, and enhancing the economic feasibility of industrial SAC recovery. The findings provide insights into advancing sustainable activated carbon management and promoting resource efficiency through improved reactivation technologies.