Synergistic treatment of heavy metals in municipal solid waste incineration fly ash with geopolymer and chemical stabilizers

Municipal solid waste incineration fly ash (MSWI-FA) is globally defined as hazardous waste and needs stabilization treatment. In this paper, synergistic treatment by geopolymerization and chemical stabilizers for the heavy metals in MSWI-FA was proposed, and its mechanism was further investigated. The leaching test showed that the concentration of Cu, Cr, Cd, Ni, Zn and Pb could meet the requirement of disposal standard, with more than 99.8% been effectively stabilized while Cr and Ni were below the quantification limits. The MSWI-FA was activated in geological polymerization process and produced Al/Si-based hydration products, while the chemical stabilizers formed chelates with heavy metals, yielding double effects on the geopolymerization. Therefore, with the co-effectiveness of the two processes, most of the heavy metals were firmly stabilized in the compound structure. The developed geopolymerization procedure had potential applications for treating heavy metals in MSWI-FA.