Utilization of municipal solid waste incineration fly ash as construction materials based on geopolymerization

Abstract

Incineration has been widely used to dispose municipal solid wastes (MSWs) with heat recovery. The generation of fly ash (FA, around 3∼5 wt% of the fed amount) that is normally defined as hazardous wastes remains a serious problem. It is ideal to work out a way to reutilize FA for valuable use instead of landfilling. As a novel utilization technology for municipal solid waste incineration (MSWI) fly ash, geopolymerization can produce geopolymer as construction materials with the advantages of low energy consumption, low pollution and high utilization rate. In this paper, metakaolin (MK) and washed fly ash (WFA) were used to prepare MSWI fly ash-based geopolymer (FAG) with alkali activator. Besides, the strength, heavy metals immobilization and acid resistance of FAG were in detail studied. Under the proper formulation, all the prepared FAGs exhibited strength higher than MU15 level (≥15 MPa) and the maximized one reached MU30 (≥30 MPa). Heavy metals including Cr, Mn, Cu, As, Pb, Zn and Cd had a immobilization rate of more than 92%, and others like As, Pb and Zn were nearly fully immobilized. As for the simulated testing for acid rain scenario, FAG could still fix up the heavy metals well indicating a controllable risk for the environment, which could be ascribed be its high acid neutralization capacity. In a word, this work reports a feasible method for treatment and resource reutilization of MSWI fly ash.