An experimental and thermodynamic equilibrium investigation of the Pb, Zn, Cr, Cu, Mn and Ni partitioning during sewage sludge incineration

The effects of different chlorides and operational conditions on the distribution and speciation of six heavy metals (Pb, Zn, Cr, Cu, Mn and Ni) during sludge incineration were investigated using a simulated laboratory tubular-furnace reactor. A thermodynamic equilibrium investigation using the Fact...

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Bibliographic Details
Published in:Journal of environmental sciences (China) 2015-09, Vol.35, p.43-54
Main Authors: Liu, Jingyong, Fu, Jiewen, Ning, Xun'an, Sun, Shuiyu, Wang, Yujie, Xie, Wuming, Huang, Shaosong, Zhong, Sheng
Format: Article
Language:English
Subjects:
Chlorides - chemistry
Chlorine
Chlorine - chemistry
Coal Ash - analysis
Heavy metal
Incineration
Metals, Heavy - chemistry
Models, Chemical
Sewage - chemistry
Sludge incineration
Thermodynamic equilibrium calculations
Thermodynamics
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Summary:The effects of different chlorides and operational conditions on the distribution and speciation of six heavy metals (Pb, Zn, Cr, Cu, Mn and Ni) during sludge incineration were investigated using a simulated laboratory tubular-furnace reactor. A thermodynamic equilibrium investigation using the FactSage software was performed to compare the experimental results. The results indicate that the volatility of the target metals was enhanced as the chlorine concentration increased. Inorganic-Cl influenced the volatilization of heavy metals in the order of Pb>Zn>Cr>Cu>Mn>Ni. However, the effects of organic-Cl on the volatility of Mn, Pb and Cu were greater than the effects on Zn, Cr and Ni. With increasing combustion temperature, the presence of organic-Cl (PVC) and inorganic-Cl (NaCl) improved the transfer of Pb and Zn from bottom ash to fly ash or fuse gas. However, the presence of chloride had no obvious influence on Mn, Cu and Ni. Increased retention time could increase the volatilization rate of heavy metals; however, this effect was insignificant. During the incineration process, Pb readily formed PbSiO4 and remained in the bottom ash. Different Pb compounds, primarily the volatile PbCl2, were found in the gas phase after the addition of NaCl; the dominant Pb compounds in the gas phase after the addition of PVC were PbCl2, Pb(ClO4)2 and PbCl2O4.
ISSN:1001-0742
1878-7320
DOI:10.1016/j.jes.2015.01.027