Yang Yan-Yan, Xie Dan-Ping, Fu Jian-Ping, Chen Xiao-Yan, Yin Wen-Hua, Han Jing-Lei, Zhang Su-Kun, Zhang Lu, Xiao Tao
South China Institute of Environment Sciences, Ministry of Ecology and Environment, Guangzhou 510655, China.
Huan Jing Ke Xue. 2022 Aug 8;43(8):3990-3997. doi: 10.13227/j.hjkx.202110197.
The pollution level, emission characteristics, and emission factors of PCDD/Fs from a number of steel plants were investigated in a particular province of China. The results showed that the concentration of PCDD/Fs was at a low level and decreased by 1-2 orders of magnitude compared with that in 2005-2019. In detail, the concentrations of PCDD/Fs ranged from 0.003-0.557 ng·m(I-TEQ), and the mean value was 0.165 ng·m for the sintering process. Moreover, the concentrations of PCDD/Fs ranged from 0.006 to 0.057 ng·m, and the mean value was 0.025 ng·m for the electric furnace process. In addition, the concentration of PCDD/Fs in the iron and steel industry from 2005 to 2020 increased first and then decreased, especially after the implementation of the new emission standard and the ultra-low emission control of conventional pollutants such as smoke, showing a significant decline. The results of fingerprint analysis showed that 2,3,7,8-TCDF was the largest congener contributing to the mass concentration, and lower chlorinated PCDFs were increased. This result differed from those of previous studies in which highly chlorinated PCDFs and PCDDs dominated, indicating that the generation source of PCDD/Fs had changed. The congener and isomer profiles of PCDD/Fs in flue gas from the sintering process were similar to those in the flue gas from the electric furnace process. Additionally, showing the characteristics of the typical high-temperature thermal process, the de novo synthesis may be the dominant mechanism of formation of PCDD/Fs in the sintering process and electric furnace process. The emission factor was 0.003-0.5 μg·t (I-TEQ), and the average emission factor was (0.18±0.22) μg·t for the sintering process. The emission factor was 0.04-0.5 μg·t, and the average emission factor was (0.27±0.23) μg·t for the electric furnace process. These values were far lower than those of the standard toolkit for identification and quantification of dioxin and furan emissions released by UNEP in 2013 and the emission factors in the dioxin emission inventory of China in 2004. It is suggested that the emission factors of PCDD/Fs in the iron and steel industry of China should be studied and updated.
对中国某省多家钢铁厂二噁英/呋喃（PCDD/Fs）的污染水平、排放特征及排放因子进行了调查。结果表明，PCDD/Fs浓度处于较低水平，与2005 - 2019年相比下降了1 - 2个数量级。具体而言，烧结过程中PCDD/Fs浓度范围为0.003 - 0.557 ng·m（以毒性当量计），平均值为0.165 ng·m；电炉过程中PCDD/Fs浓度范围为0.006至0.057 ng·m，平均值为0.025 ng·m。此外，2005 - 2020年钢铁行业PCDD/Fs浓度先升后降，特别是在新排放标准实施以及对烟尘等常规污染物进行超低排放控制后，呈现显著下降。指纹分析结果表明，2,3,7,8 - TCDF是对质量浓度贡献最大的同系物，且低氯代PCDFs有所增加。这一结果与以往高氯代PCDFs和PCDDs占主导的研究结果不同，表明PCDD/Fs的产生源发生了变化。烧结过程烟气中PCDD/Fs的同系物和异构体分布与电炉过程烟气相似。此外，呈现典型高温热过程特征，从头合成可能是烧结过程和电炉过程中PCDD/Fs形成的主要机制。烧结过程的排放因子为0.003 - 0.5 μg·t（以毒性当量计），平均排放因子为(0.18±0.22) μg·t；电炉过程的排放因子为0.04 - 0.5 μg·t，平均排放因子为(0.27±0.23) μg·t。这些值远低于联合国环境规划署2013年发布的二噁英和呋喃排放识别与量化标准工具包中的值以及2004年中国二噁英排放清单中的排放因子。建议对中国钢铁行业PCDD/Fs的排放因子进行研究和更新。
