Water repellents for the leaching control of heavy metals in municipal solid waste incineration fly ash

Suppression of heavy metal elution from municipal solid waste incineration (MSWI) fly ash by cement or geopolymer solidification was studied. When these approaches are implemented, however, the volume of the solidified body increases as a consequence of the solidifying agent addition. Considering that residual landfill disposal capacity is decreasing in the long term, a novel method to suppress the elution of heavy metals from MSWI fly ash without decreasing the disposal capacity is needed. We studied four different water repellents and the results indicated that heavy metal elution can easily be suppressed by impregnating the incineration fly ash with commercially available silane oligomers, alkyl alkoxysilane compounds, and water repellents like fatty acids.