Co-processing of MSWI fly ash and copper smelting wastewater and the leaching behavior of the co-processing products in landfill leachate

The solidification/stabilization of municipal solid waste incineration (MSWI) fly ash is required before it enters a landfill, and water is needed in this process. At the same time, a large quantity of Ca(OH)(2) is consumed during copper smelting wastewater treatment. The purpose of this study was to utilize both MSWI fly ash and copper smelting wastewater in a co-processing process. The elements Cr, Cu, Pb, and As were selected to study the stability of the co-processing products. The effects of H2SO4 and As in copper smelting wastewater on the stability of the co-processing products were studied. A TCLP leaching procedure and a BCR sequential extraction procedure were conducted to evaluate the stability of the co-processing products. H2SO4 (0-50 g/L) in simulated copper smelting wastewater had no significant influence on the stability of Cr and Cu; however, it enhanced the stability of Pb and As in the co-processing products. The stability of Cu and Pb increased with the content of As (0-5000 mg/L) in simulated copper smelting wastewater, while the stability of Cr and As decreased. When the co-processing products came into contact with the landfill leachate, the leaching of Cu was promoted. The co-processing products helped to reduce the concentration of Pb and As in landfill leachate. The results indicated that a chelating agent is needed to enhance the stabilization of Cu. (C) 2019 Elsevier Ltd. All rights reserved.