Stabilization of residues obtained from the treatment of laboratory waste. Part 1 - Treatment path of metals in a plasma melting system

The objective of this study is to investigate the treatment path of metals during the plasma vitrification of fly ash, bottom ash, sludge, and activated carbon collected from a laboratory waste treatment plant. Sampling, digestion, and analysis procedures that followed the standard methods of the Taiwan Environmental Protection Administration were used to determine the composition of the input and output materials. The microstructure was qualitatively examined using a scanning electron microscope. The results show that the vitrification process successfully vitrified the toxic input materials into a stable, glassy, amorphous slag. During vitrification, metals with low boiling points (As, Cd, Hg, Pb, and Zn) were vaporized into the flue gas. Metals with high boiling points and high specific weights went into the ingot, and the residual metals remained in the molten materials as the slag. The distribution of metals shows their behavior during vitri-fication and can provide a reference for vitrifying hazardous materials.