Optimization of municipal solid waste incineration bottom ash geopolymer with granulated blast furnace slag (GGBFS): Microstructural development and heavy metal solidification mechanism

Abstract

The enormous increase in municipal solid waste (MSW) has resulted in a large volume of incinerator bottom ash (MSWIBA). With the widespread adoption of trash incineration technologies, the disposal of significant amounts of MSWIBA is inevitable to minimize groundwater and soil contamination from direct landfills.MSWIBA has an oxide composition similar to silicate cement and might be utilized as an alkali-activated materials (AAMs). However, because MSWIBA has a low active calcium content, the mechanical characteristics of AAMs made from MSWIBA alone are unsatisfactory. As a result, this work investigated the optimization of mechanical characteristics and microstructure of alkali-activated bottom ash material (AABAM) by integrating the high calcium mineral GGBFS. The environmental friendliness of AABAM was assessed using mechanical compressive strength tests, XRD, SEM, EDS, MIP, and heavy metal leaching. The results showed that the inclusion of GGBFS greatly improved the early strength of AABAM, with compressive strength increasing by up to 663.7 % to 43.0 MPa after 28 days of curing. Meanwhile, GGBFS boosted gel formation and optimized AABAM porosity to better enclose the metal elements, with Cr solidification efficiency reaching 86.4 %. The synergistic treatment of MSWIBA and GGBFS not only resulted in the efficient use of solid waste resources but also provided a novel option for municipal solid waste management.

Keywords

• Municipal solid waste incineration bottom ash
• Alkali - activated material
• Ground granulated blast - furnace slag particle
• Heavy metal