The term "Spent activated carbon" refers to activated carbon and its products that have lost their original functionality due to exhausted adsorption capacity, structural damage, or performance degradation during applications such as water treatment, gas purification, chemical production, food and pharmaceutical industries, and environmental remediation, or that, although not entirely devoid of utility, have been discarded. Through processing methods such as collection, regeneration, pyrolysis, or metal recovery, this type of waste activated carbon can be reactivated for use in adsorption and purification processes, or utilized as fuel, chemical feedstock, or construction material admixture, thereby entering the resource recovery and reuse cycle.