Heavy metal immobilization under weak acidic condition of municipal solid waste incineration fly ash treated by geocasting and calcination

Abstract

Incineration is one of the major treatment of Munisipal Solid Waste (MSW) generation. And from incineration, Fly Ash is byproduct from MSW incineration treatment and it’s required extra treatment with toxic heavy metal elements such as Pb and Zn. Chelate treatment is most common treatment in Japan to immobilize heavy metal. But chelate treatment has possibility of chemical/biological decomposition and cause long-term high concentration of organic hydrocarbons in landfill site as well as leaching of heavy metals to the environment. In this study, for finding alternative fly ash treatment, authors focus to replace fly ash to fluidized bed combustor sand. But fluidized bed sand requires bigger size than fly ash. Therefore, geocasting was used in this research to aggregate to bigger particles with physical requirements of heat carrier. Samples prepared raw fly ash, geocasted fly ash, and calcinated fly ash. In this research, SEM-EDX and TCLP leaching test were used. The characteristics of the geopolymer foams shows that porosity and irregular shape. And TCLP leaching test result shows geocasting can reduce probability of heavy metal leaching riskness.