Effect of waste-derived soil amendments on mitigating leaching impacts from municipal solid waste incineration (MSWI) ash.

This study explores modifying a sandy soil with a low solid to liquid partitioning coefficient (K _d ) by adding amendments including iron-rich industrial slag byproducts and biochars, which contain sorption sites for trace metals present in MSWI ash leachate (notably Sb, cited as a concern for reuse applications). K _d values for Sb were determined for the sandy soil to be as low as 1.6 ± 0.1 L/kg. With amendments, K _d values varied from 1.4 ± 0.2 L/kg for combined ash leachate exposed to a blend of sandy soil and 20% iron slag, to 990 L/kg for combined ash leachate exposed to a blend of sandy soil and 20% magnetic solids. A blend of 20% magnetic solids showed orders of magnitude increase beyond 100% sandy soil. The biochars showed limited capacity to reduce leached Sb in the ash-derived leachate, which is likely due to negative surface charges of the biochars and Sb at basic pH. A risk assessment (US EPA IWEM) performed using experimental K _d for each blend suggests that using soil amendments could reduce leached concentrations at points of concern, which could open additional avenues for ash reuse.
Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Dr. Timothy Townsend reports financial support was provided by Hinkley Center for Solid and Hazardous Waste Management.
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