Electrodialytically treated MSWI fly ash use in clay bricks

Abstract

Fly ash from municipal solid waste incineration (MSWI) is classified as hazardous waste, due to high heavy metal and salt content. Thus, beneficial use is restricted, and the fly ash hazardousness should be reduced before testing reuse options. Electrodialytic treatment can remove heavy metals and soluble salts from an MSWI fly ash suspension by applying an electric current to the suspension and thus be used to decontaminate the MSWI fly ash. In Greenland, MSWI fly ash is stored at uncontrolled disposal sites, and a more sustainable solution for handling fly ash is needed. At the same time, most construction materials are imported from Europe to Greenland, and increased use of local materials would greatly benefit the circular economy in the area. In this study, it was investigated if local Greenlandic resources could have potential in brickmaking. Two different clays; a Danish clay (used commercially in brick production) and one Greenlandic (not used commercially) and raw and electrodialytically treated MSWI fly ash from Sisimiut, Greenland were used. Small clay discs with 0, 10, 20 and 30% substitution of clay by MSWI fly ash were fired at 1000 °C for 24 h. Substituting clay with fly ash generally resulted in lower technical properties of the clay discs. Nevertheless, from this initial screening, the clay discs with electrodialytically treated fly ash and Greenlandic clay showed the lowest porosity and water absorption, which could be beneficial for use as construction material in cold climates.