Prediction of physical separation of metals from soils contaminated with municipal solid waste ashes and metallurgical residues

Abstract

Environmental legislation is forcing industrialized countries to rehabilitate contaminated lands. Expensive solutions are available to treat soils contaminated by metals (e.g., solidification, stabilization, and landfilling). Physical remediation techniques, which are less expensive, are able to efficiently separate metals from contaminated soils under specific physical conditions. In the current study, densimetric and mineralogical characterization of fractions of soil between 0.25 and 4 mm contaminated by municipal solid waste (MSW) ashes and metallurgical waste was performed. This characterization confirmed the usefulness of the jig and wet shaking table for separating the metal contaminants from the soil. Mineralogical characterization allowed the prediction of treatment efficiencies and potential limits. The jig performance was optimized based on densimetric characterization. Water washing coupled with ferrous material extraction using magnetic separation, and, attrition scrubbing coupled with the jig and wet shaking table, led to a removal yield varying from 42.1% to 83.4% for Ba, Cu, Pb, Sn, and Zn from the fraction of soil >0.25 mm contaminated by MSW ashes. The recovered treated mass varied from 57.1% to 73.4% (by weight). For the fraction of soil >0.25 mm contaminated with metallurgical residues, Cu and Zn removal yields were higher than 57.5%. The recovered treated mass from this soil fraction corresponded to 64.8% (by weight). Depending on the level and leachability of contaminants, the soil fractions <0.25 mm were recommended for appropriate treatments (solidification or stabilization) or for safe disposal via landfills.

Environmental and health impacts assessment of long-term naturally-weathered municipal solid waste incineration ashes deposited in soil—old burden in Bratislava city, Slovakia

“…Similar to the results of this study, these technogenic materials are enriched in metal (loid)s ( Table S8 – note the striking coincidence of metal (loid) concentrations in MSWI ashes deposited/buried in soils from different countries), while metal (loid) concentrations in the surrounding or overlying soil are usually lower and dependent on the distance from the ash deposits and the ash content of the soil [ 107 , 112 ]. Several authors characterised the mineralogical composition of old MSWI ashes and showed that quartz, calcite, magnetite, hematite and possibly albite were the dominant minerals [ 51 , 63 , [109] , [110] , [111] ], which is also a typical feature of the old MSWI ashes of this study. Limited leaching of metal (loid)s is characteristic of incineration ashes exposed to atmospheric conditions for a long time.…”

“…To the best of our knowledge, few studies have addressed metal (loid) concentrations in soils containing or in contact with waste incinerator ashes [ [107] , [108] , [109] , [110] , [111] , [112] ]. Similar to the results of this study, these technogenic materials are enriched in metal (loid)s ( Table S8 – note the striking coincidence of metal (loid) concentrations in MSWI ashes deposited/buried in soils from different countries), while metal (loid) concentrations in the surrounding or overlying soil are usually lower and dependent on the distance from the ash deposits and the ash content of the soil [ 107 , 112 ].…”