Mumin Rao1, Xiangbo Zou1, Ji Ye1, Yunfeng Ma This email address is being protected from spambots. You need JavaScript enabled to view it.2, Tieying Mao2, Xiaoqing Lin This email address is being protected from spambots. You need JavaScript enabled to view it.2, Xiaodong Li2, Jianhua Yan2, Shiwei Qin1, Cao Kuang1

1 Guangdong Energy Group Science and Technology Research Institute Co., Ltd. Guangzhou 510630, China
2 State Key Laboratory for Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou 310027, China


Received: July 23, 2021
Revised: August 29, 2021
Accepted: August 29, 2021

 Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.


Download Citation: ||https://doi.org/10.4209/aaqr.210179  


Cite this article:

Rao, M., Zou, X., Ye, J., Ma, Y., Mao, T., Lin, X., Li, X., Yan, J., Qin, S., Kuang, C. (2021). Formation Characteristics of PCDD/Fs in the Co-combustion and Pyrolysis Process of Coal and Sewage Sludge. Aerosol Air Qual. Res. https://doi.org/10.4209/aaqr.210179


HIGHLIGHTS

  • Abundant sources of C, Cl and Fe well supported PCDD/F formation.
  • Pyrolysis of SS generated more PCDD/F (0.59 ng g1) than combustion process (0.34 ng g1).
  • PCDD/F formation (0.42–1.70 ng g1) increased as increasing proportion of SS (0–5%).
  • De novo synthesis was the major formation route of PCDD/F in co-combustion process.
 

ABSTRACT


Co-combustion technology of coal and sewage sludge (SS) was encouraged and recommended in China. Previous studies most focused on its influence on combustion characteristics, migration characteristics of heavy metals in fly ash, and emission of conventional pollutants, etc., but less reported the formation characteristics of polychlorinated-ρ-dibenzodioxins and dibenzofurans (PCDD/Fs). To well reveal it, this study carried out five parallel experiments, including the pyrolysis of SS, the combustion of SS, the co-combustion of coal and SS with the proportion of 0%, 2.5% and 5%, respectively. The emission concentration of PCDD/Fs respectively increased from 0.42 ng g-1 (0.0022 ng I-TEQ g-1) to 0.54 ng g-1 (0.0030 ng I-TEQ g-1) and 1.70 ng g-1 (0.0305 ng I-TEQ g-1) with increasing blending proportion of SS. The dominant part was also changed from PCDF (0.32 ng g-1 in M-0%, 0.38 ng g-1 in M-2.5%) to PCDD (1.11 ng g-1 in M-5%). The formation concentration of PCDD/Fs in the combustion process of SS was about 0.34 ng g-1 (0.0019 ng I-TEQ g-1). In the pyrolysis process of SS, the concentration of PCDD/Fs was 0.59 ng g-1 (0.0037 ng I-TEQ g-1). The de novo synthesis should be the major formation pathway of PCDD/Fs in the co-combustion process of coal and SS. On the basis of sufficient carbon sources, the PCA analysis revealed the chlorine source (Cl) and metal catalyst (Fe) should contribute a lot on the formation of PCDD/Fs. The results paved the way for further optimization on the operation of co-combustion of coal and SS and assist in controlling the PCDD/F emission from co-combustion process.


Keywords: Co-combustion of coal and sewage sludge, Polychlorinated-ρ-dibenzodioxins and dibenzofurans, Pyrolysis of sewage sludge, Formation pathways, Congener distribution




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