Evaluation of the distribution patterns of Pb, Cu and Cd from MSWI fly ash during thermal treatment by sequential extraction procedure

This study investigated the fate of polybrominated diphenyl ethers (PBDEs) in a thermal treatment system that was employed to recover the metals from the electric arc furnace (EAF) fly ash. After 1450°C thermal treatment, the content of PBDEs in the EAF fly ash (50128 ng/kg) was greatly reduced by 98.9%, based on the solid destruction efficiency (SDE). The sums of five PBDE contents in ingot and slag were 86.0 and 32.3 ng/kg, respectively, revealing that the residual PBDE content in slag was much lower than those in woodland (180 and 710 ng/kg) and grassland (440 ng/kg) soils (Harrad and Hunter, 2006). With this PBDE level, the slag can be either safely disposed of in landfills or utilized as construction material. After the 1450°C thermal treatment and 1200°C secondary combustion, 95.8% of the PBDEs were destroyed or removed without air pollution control devices (APCDs). The PBDE concentrations in cooling unit and filter (APCDs) were 8810 and 327 pg/Nm 3 , respectively, while that in the PUF cartridges (final emission) was 13009 pg/Nm 3 . However, the PBDE concentration of the untreated flue gas was 22.1 ng/Nm 3 , which is still higher than that measured in the exhausts from various stationary sources (15.7-46.7 ng/Nm 3 ) (Wang et al., 2010a, c). Fortunately, the concentration of PBDEs can be effectively reduced to a much lower level (13.0 ng/Nm 3 ) in the flue gas. In addition, after the Pearson correlation analyses, the logarithm contents of PBDEs and PCDD/Fs showed a statistically high correlation (r = 0.930-1.000). Consequently, thermal treatment with APCDs can effectively reduce the PBDEs in EAF fly ash, while the heavy metals can also be recovered.

Section: Introductionmentioning

confidence: 99%

Emissions of Polybrominated Diphenyl Ethers during the Thermal Treatment for Electric Arc Furnace Fly Ash

Lin

Zhou

Shih

et al. 2012

“…The vitrification approach has been shown to successfully treat hazardous materials, such as fly ash and sludge (Li et al, 2007a;Chou et al, 2009;Kuo et al, 2009;Wang et al, 2010c). There are three kinds of vitrification depending on the heat source: electric melting, burner melting and blast melting.…”

Section: Introductionmentioning

confidence: 99%

Fate of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans during the Thermal Treatment of Electric Arc Furnace Fly Ash

Lin

Zhou

Shih

et al. 2011

Thermal treatment is often employed to recover the metals contained in electric arc furnace (EAF) fly ash, which is considered a major source of PCDD/Fs. After the present treatment, the mass and volume of untreated material (EAF fly ash + cullet) were significantly reduced by 44.2 and 89.2%, respectively; meanwhile the density increased significantly by 476%. These results indicate that the mass and volume of EAF fly ash can be effectively reduced to benefit the further disposal in landfill. Additionally, this study also investigated the fate of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) during the thermal treatment. For the EAF fly ash with an original PCDD

“…The production of waste water after the flotation of fly ash is undesirable. Some soluble heavy metal compounds, such as Cd or Zn compounds, showed a high release rate and were transferred into the wastewater.The waste water may be used for the neutralization of other waste streams or may be precipitated to form a solid and then separated by filtration (Chou et al, 2009). The next stage of this research will focus on the treatment and recirculation of effluents containing heavy metals after flotation.…”

Section: Proposed Procedures For Reburning Froths After the Flotation mentioning

confidence: 99%

Reburning Treatment of the Froths Obtained after the Flotation of Incinerator Fly Ash

Wei

Liu²,

Liu

et al. 2017

Flotation has been proven to successfully remove most polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) and carbon constituents from hospital solid waste incinerator (HSWI) fly ash. The resultant froths contain large quantities of carbon constituents that can reburn in the incinerator. In this paper, the reburning behavior of froths at temperatures from 800°C to 1200°C was compared with that of HSWI fly ash. Results showed that the destruction efficiency of PCDD/Fs was higher in the froths than in the fly ash at the same reburning temperature. The destruction efficiencies of PCDD/Fs in the froths exceeded 98% at temperatures higher than 1000°C. The volatilization ratio of Pb, Zn, and Cu was lower in the froths than in the fly ash. Furthermore, reburning of the froths can achieve energy recovery of the carbon constituents. Therefore, flotation followed by reburning treatment in a combustion chamber could be a suitable process for the detoxification and reutilization of HSWI fly ash.