Designing low-carbon cement-free binders for stabilization/solidification of MSWI fly ash

J Environ Manage. 2023 Aug 1:339:117938. doi: 10.1016/j.jenvman.2023.117938. Epub 2023 Apr 18.

Abstract

Low-carbon and high-efficiency binder is desirable for sustainable treatment of municipal solid waste incineration fly ash (MSWI FA). In this study, CaO or MgO was used to activate ground granulated blast furnace slag (GGBS) to form calcium silicate hydrate and magnesium silica hydrate gel for stabilization/solidification of hazardous MSWI FA. Experimental results showed that potential toxic elements (PTEs), such as Pb and Zn, significantly inhibited the formation of reaction products in CaO-GGBS system due to the complexation between Ca(OH)2 and PTEs, whereas PTEs only had insignificant inhibition on transformation from MgO to Mg(OH)2 in MgO-GGBS system, resulting in lower leachabilities of PTEs and higher mechanical strengths. Stabilization/solidification experiments demonstrated that MSWI FA (70 wt%) could be recycled by MgO-GGBS binder (30 wt%) into blocks with desirable 28-day compressive strengths (3.9 MPa) and PTEs immobilization efficiencies (99.8% for Zn and 99.7% for Pb). This work provides mechanistic insights on the immobilization mechanisms of PTEs in CaO/MgO-GGBS systems and suggests a promising MgO-GGBS binder for low-carbon treatment of MSWI FA.

Keywords: Hazardous waste treatment; Low-carbon stabilization/solidification; PTEs leachability; Sustainable waste management; Waste incineration fly ash.

MeSH terms

  • Carbon
  • Coal Ash
  • Incineration / methods
  • Lead
  • Magnesium Oxide
  • Metals, Heavy* / analysis
  • Particulate Matter
  • Refuse Disposal* / methods
  • Solid Waste / analysis

Substances

  • Coal Ash
  • Particulate Matter
  • Carbon
  • Magnesium Oxide
  • Lead
  • Metals, Heavy
  • Solid Waste