FCC spent catalyst as an alternative reagent in Mo-contaminated hazardous waste enhanced stabilization

Hazardous wastes containing heavy metals must be stabilized through the addition of appropriate and costly chemical reagents before they can be safely disposed in non-hazardous waste landfill. Although effective, this practice can also significantly increase the waste final mass. This work focuses on the possibility of using another Mo contaminated waste, as an alternative reagent, to partially stabilize critical contaminant leaching trough chemical-physical interactions. Thanks to its unusual properties, spent fluid catalytic cracking (FCCSC) catalyst, classified as hazardous waste, was tested here as good candidate for Mo-contaminated waste partial stabilization. Results highlighted that FCCSC can be effective in drastically reducing the Molybdenum leaching below the legal limit for non-hazardous waste landfill disposal while significantly limiting the increase of the final mass of waste to be disposed with a substantial reduction of the industrial treatment cost, landfill volume requirement and overall environmental burden. By minimizing the waste to be landfilled, this research supports both the European directives and policies on sustainable waste management strategies and BAT (Best Available Techniques) for the treatment of industrial wastes within a circular economy framework.