Pollution characteristics of thermal treatments for elutriated ashes. Part 2: Comparison with incineration system and plasma melting system

This study investigated the pollution characteristics of a plasma melting system and compared its performance with that of the incineration system that was reported in Part 1 of this study. The heavy metals and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in input and output materials during elutriation and plasma melting processes were analyzed. The elutriation process dissolved NaCl and caused an increase in the PCDD/Fs of raw mixed incinerator ashes. After being melted with waste silica gel, the PCDD/F level of elutriated ashes was greatly reduced, and the output mass/input mass ratio was only 0.000188, which was much lower than that of the co-incineration process (0.34). The powdery and porous structure of elutriated ashes was transformed into a glassy amorphous structure after the plasma melting process, and the slag was regarded as a non-hazardous product that can be recycled directly. The concentration of pollutants in the flue gas was much lower than the regulated standards. Although the operational cost of the plasma melting process is higher than that of the incineration process, the plasma melting process has a superior effect on the stabilization of elutriated ashes and is thus a preferable treatment method.