Abstract
The leaching behaviors of four heavy metals (Zn, Pb, Cu and Cr) from unbounded municipal solid waste incineration-bottom ash aggregate (MSWI-BAA) and permeable asphalt (PA) mixture containing MSWI-BAA were investigated in the laboratory. The horizontal vibration extraction procedure (HVEP) test and a simulated leaching experiment were conducted on MSWI-BAA with three particle sizes, but only the simulated leaching experiment was carried out on a type of PA specimen (PAC-13) with and without these MSWI-BAAs. Leaching data were analyzed to investigate the leaching characteristics, identify the factors affecting leaching and assess the impact on the surrounding environment. Results indicated that the leaching process was comprehensively influenced by contact time, leaching metal species and MSWI-BAA particle size, regardless of MSWI-BAA alone or used in PAC-13 mixture. The leaching concentrations of Cr, Zn and Pb from MSWI-BAA in HVEP testing was strongly related to MSWI-BAA particle size. The use of MSWI-BAA in PAC-13 mixture did not change the basic tendency of heavy metal leaching, but it led to an increase of Cr and Zn in leachate overall. The leachate from the MSWI-BAA and PAC-13 mixture with MSWI-BAA was shown to be safe for irrigation and would have very little negative impact on surrounding surface and underground water quality.
Highlights
Incineration with energy recovery is recommended as a preferred option for dealing with municipal solid waste (MSW) to effectively reduce the original waste volume and mass by approximately 90%and 70%, respectively, and generate electricity and heat [1,2,3]
MSWI-BAA samples with three particle sizes obtained through the horizontal vibration extraction procedure (HVEP) test
An MSWI-BAA with a larger particle size was likely to release more Cr and Zn, and an MSWI-BAA with smaller particles was likely to release more Pb. These results suggest that the heavy metal leaching from unbounded MSWI-BAA
Summary
Incineration with energy recovery is recommended as a preferred option for dealing with municipal solid waste (MSW) to effectively reduce the original waste volume and mass by approximately 90%and 70%, respectively, and generate electricity and heat [1,2,3]. A considerable amount of residual material is still generated after the incineration process: typically MSW incineration fly ash (MSWI-FA) and MSW incineration bottom ash (MSWI-BA) [4,5]. Of the total residual by mass and is complex, consisting of combustion residue and non-combustible constituents of the waste feed [6,7,8]. In Europe and Asia, MSWI-BA is often classified as non-hazardous waste [9]. For this reason, MSWI-BA is commonly discarded in landfills. In 2017, 84.63 million tons of MSW were treated by incineration in China, accounting for nearly
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