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Volume 16, No. 7, July 2016, Pages 1569-1578 PDF(372 KB)  
doi: 10.4209/aaqr.2016.01.0001   

Mass Concentrations of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans (PCDD/Fs) and Heavy Metals in Different Size Fractions of Hospital Solid Waste Incinerator Fly Ash Particles

Guoxia Wei1, Hanqiao Liu2, Rui Zhang2, Yuwen Zhu2, Xian Xu2

1 School of Science, Tianjin Chengjian University, Tianjin 300384, China
2 School of Energy and Safety Engineering, Tianjin Chengjian University, Tianjin 300384, China

 

Highlights
  • Distribution of PCDD/Fs and heavy metals in incinerator fly ash was studied.
  • Low chlorine PCDD/Fs increased when decreasing particle size.
  • Carbonate speciation of Pb and Zn was highest in particle fraction of –38 + 25 µm.

Abstract

 

Hospital solid waste incinerator (HSWI) fly ash is an extremely complex mixture because it contains carbon constituents, toxic heavy metals, and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). We investigated the distribution of carbon constituents, PCDD/Fs, and heavy metals in the five different particle size fractions (+106 µm, –106 + 75 µm, –75 + 38 µm, –38 + 25 µm, and –25 µm) of HSWI fly ash. The loss on ignition (LOI) in the particle size fraction of –25 µm was higher than that in the particle size fractions of other sizes. Moreover, 82.63% of the fly ash particles were in the size range of –75 + 25 µm, and this particle size range was suitable for direct flotation treatment. Because powder-activated carbon adsorbed a higher amount of low-chlorinated PCDD/Fs in the gaseous phase, the concentration of each PCDD/F congener, particularly of low-chlorinated PCDD/Fs, generally increased with a decrease in the particle size. The total toxic equivalent (TEQ) of the fraction of –75 µm did not satisfy the landfill site standard (3 ng-TEQ g–1). The highest concentration of Pb, Zn, and Cd was observed in the fraction of –38 + 25 µm rather than in the fraction of –25 µm. The exchangeable speciation of Zn, Pb, and Cd was relatively high in the particle size fraction of –75 µm. The carbonate speciation of Pb and Zn was the highest in the particle size fraction of –38 + 25 µm. The leaching concentrations of Pb and Cd in all particle size fractions exceeded landfill allowable thresholds.

 

 

Keywords: Hospital solid waste incinerator; Fly ash; Size distribution; Heavy metals; PCDD/Fs.

 

 

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