Emission characteristics of polychlorinated dibenzo-p-dioxins and dibenzofurans from industrial combustion of biomass fuels

Zhang, Chunlin; Bai, Li; Yao, Qian; Li, Jiangyong; Wang, Hao; Shen, Liran; Sippula, Olli; Yang, Jun; Zhao, Jinping; Liu, Jun; Wang, Boguang

Emission characteristics of polychlorinated dibenzo-p-dioxins and dibenzofurans from industrial combustion of biomass fuels

2022

Although biomass fuel has always been regarded as a source of sustainable energy, it potentially emits polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). This study investigated PCDD/F emissions from industrial boilers fired with three types of biomass fuel (i.e., bagasse, coffee residue, and biomass pellets) via stack sampling and laboratory analysis. The measured mass concentrations of PCDD/Fs varied among the boilers from 0.0491 to 12.7 ng Nm⁻³ (11% O₂), with the calculated average international toxic equivalent quantity (I-TEQ) from 0.00195 to 1.71 ng I-TEQ Nm⁻³ (11% O₂). Some of them were beyond the limit value for municipal waste incineration. 2,3,4,7,8-PeCDF could be used as a good indicator of dioxin-induced toxicity of stack flue gases from biomass-fired boilers. The PCDFs/PCDDs ratios were more than 1, likely indicating the formation of dioxins in the boilers favored by de novo synthesis. The emission factor (EF) of total PCDD/Fs averaged 5.35 ng I-TEQ kg⁻¹ air-dry biomass (equivalent to 39.0 ng kg⁻¹ air-dry biomass). Specifically, the mean EF was 6.94 ng I-TEQ kg⁻¹ (52.6 ng kg⁻¹) for biomass-pellet-fired boiler, 11.8 ng I-TEQ kg⁻¹ (74.6 ng kg⁻¹) for coffee-residue -fired boiler, and 0.0277 ng I-TEQ kg⁻¹ (0.489 ng kg⁻¹) for bagasse-fired boilers. The annual PCDD/F emission was estimated to be 208 g I-TEQ in 2020 in China, accounting for approximately 2% of the total national annual emission of PCDD/Fs. The results can be used to develop PCDD/Fs emission inventories and offer valuable insights to authorities regarding utilizing biomass in industry in the future.

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