Migration of Cu, Zn and Cr through municipal solid waste incinerator bottom ash layer in the simulated landfill

- Cu is greatly released from the MSWI bottom ash layer over the study.
- MSWI bottom ash layer captures Zn from leachate at the initial stage of landfill.
- Zn is released from the MSWI bottom ash layer at the late stage of landfill.
- MSWI bottom ash layer shows mild effect on the migration of Cr in landfill.
- The released metals are immobilized by the sub-MSW layer.

Municipal solid waste incinerator (MSWI) bottom ash is used as the cover, intermediate cover and liner in the landfill. In this study, simulated landfills were operated for 507 days to investigate the effect of MSWI bottom ash layer on the migration of Cu, Zn and Cr. All through the study, Cu was greatly released from the MSWI bottom ash layer. Zn was captured by the MSWI bottom ash layer at the initial stage of the landfill. After then, the release of Zn from the MSWI bottom ash layer was observed, corresponding to the decline of the leachate pH. No trapping or release was found for Cr at the initial stage of the landfill. Then, a slight release of Cr from the MSWI bottom ash layer was observed. Over the study, a totally 0.93% of Cu, 0.12% of Zn, and 0.01% of Cr in the MSWI bottom ash layer were released. The released metals were not discharged to the surrounding environment. They were immobilized by the sub-MSW layer. It suggested that the MSWI bottom ash layer could not increase the metal discharge when it was used as the cover or intermediate cover in the landfill.

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