MSWI fly ash based novel solidification/stabilization matrices for heavy metals

Abstract

The possibilities of MSWI fly ash as a major constituent of novel solidification/stabilization matrices for secure landfill were investigated by mixing MSWI fly ash with rich aluminum components, which was added as bauxite cement or metakaolinite instead, to form Friedel and Ettringite phases with high fixing capacities for heavy metals. The physical properties, heavy metals-fixing capacity, mineral phases and its vibration bands in the novel matrices were characterized by compressive strength, TCLP(toxic characteristic leaching procedure), XRD (x-ray diffraction), DTG (derivative thermogravimetry), and FTIR (fourier transform infrared spectroscopy), respectively. The Tessier’s five-step sequential extraction procedure was used to analyze the fractions of chemical speciation for Pb, Cd and Zn ions. The experimental results indicate that Friedel-Ettringite based novel solidification/stabilization matrices can incorporate Pb, Cd and Zn ions effectively by physical encapsulation and chemical fixation, and it exhibits a great potential in co-landfill treatment of MSWI fly ash with some heavy metals-bearing hazardous wastes.

Keywords

MSWI fly ash / heavy metals / chemical speciation fraction / secure landfill / solidification/stabilization

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