Characterization and leachability evaluation of medical wastes incineration fly and bottom ashes and their vitrification outgrowths

Abstract

The present investigation focus on the characterization and leachability evaluation of medical wastes incineration ashes and that of their glasses, produced during vitrification with soda lime recycled glass (SLRG). Two types of ashes were examined: A Fly Ash (MFA) derived from the incinerator waste gases de-dusting system (fabric filter dust collector), and a Bottom Ash (MBA) produced from the heavier particles of the agglomerated remaining matter, which are precipitated and accumulated usually in the combustion chamber. Glasses of various syntheses were obtained during the MFA and MBA vitrification with various amounts of silica scrap (20, 25 and 30wt% for MBA and 50, 55 and 60wt% for MFA). The characterization of both ashes and that of their vitreous products was carried out by means of chemical analysis and mineralogical analysis by X-ray diffraction. MFA microstructure and morphological characteristics were examined by scanning electron microscopy and transmission electron microscopy, whereas the corresponding of MBA and the produced glasses were studied in polished section through scanning electron microscopy. Their behaviour during leaching was determined by the Toxicity Characteristic Leaching Procedure test and the EN 12457-2 compliance leaching test and according to the results both ashes should be treated as hazardous wastes and in case of landfilling they should be disposed of at appropriate, regulation-prescribed waste dumps. On the other hand in case of their vitreous outgrowths, the trace elements detected in the leachates were well below the corresponding regulatory limits.