Abstract

ABSTRACT In this paper, a bench-scale simulated cement kiln was used to study the emission characteristics, as well as the main factors that influence them, of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), heavy metals, and hydrogen chloride (HCl) in flue gas generated by co-processing combustible components of aged refuse (CCAR). The main combustible components were plastics, textiles, and woods, and the calorific value of CCAR (> 2.5 × 107 J kg–1) was much higher than that of original municipal solid waste (OMSW). De novo synthesis was the dominant PCDD/F formation pathway during the co-processing of CCAR, and CCAR with higher chlorine and Cu content tended to generate more PCDD/Fs. The concentration of the PCDD/Fs produced by the pure raw meal used in this experiment was 3.25 ng m–3 (0.33 ng I-TEQ m–3), which increased to 3.87 (0.56), 6.27 (0.69), or 5.77 ng m–3 (0.72 ng I-TEQ m–3) when CCAR from different landfill periods was mixed in, with the more chlorinated substituted PCDD/F congeners, especially 1,2,3,4,6,7,8-HpCDF, exhibiting relatively high concentrations. However, the less chlorinated substituted PCDD/Fs, especially 2,3,7,8-PCDD and 2,3,4,7,8-PeCDF, contributed the major share of the I-TEQ value. Feeding CCAR through the raw meal inlet increased the formation of PCDD/Fs. Principal component analysis (PCA) was conducted to identify the similarities and differences between congener distributions among the various samples. Overall, the co-processing of CCAR increases the concentration of pollutants and requires more effective technologies for controlling emissions.

Highlights

  • Aged refuse that is bio-stabilized through years in the landfill (Xie et al, 2012) can be called “stabilized waste” or “mineralized waste.” Substances such as kitchen waste, plants, and paper in the original municipal solid waste (OMSW) are basically decomposed into soil after long-term landfill, so the nature of the aged refuse is basically stable

  • A bench-scale simulated cement kiln was used to study the emission characteristics, as well as the main factors that influence them, of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), heavy metals, and hydrogen chloride (HCl) in flue gas generated by co-processing combustible components of aged refuse (CCAR)

  • The results show that the co-processing of CCAR does promote the formation of polychlorinated dibenzofurans (PCDD/Fs), which is consistent with the results reported by other research (Zhan et al, 2016b)

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Summary

Introduction

Aged refuse that is bio-stabilized through years in the landfill (Xie et al, 2012) can be called “stabilized waste” or “mineralized waste.” Substances such as kitchen waste, plants, and paper in the original municipal solid waste (OMSW) are basically decomposed into soil after long-term landfill, so the nature of the aged refuse is basically stable. Aged refuse that is bio-stabilized through years in the landfill (Xie et al, 2012) can be called “stabilized waste” or “mineralized waste.”. Substances such as kitchen waste, plants, and paper in the original municipal solid waste (OMSW) are basically decomposed into soil after long-term landfill, so the nature of the aged refuse is basically stable. Aged refuse can be divided into two categories according to the size of the particle: fine-grained (< 15 mm) and coarse-grained (> 15 mm). The main combustible components of coarse-grained aged refuse are substances that can be recycled and utilized, such as plastics, textiles, and woods (Zhao et al, 2001, 2002). The total aged refuse in the world reached 2 billion tons, of

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