School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 510641, China.
South China Institute of Environmental Sciences, Ministry of Environmental Protection (MEP), Guangzhou, 410665, China.
Environ Sci Pollut Res Int. 2017 Aug;24(24):19807-19815. doi: 10.1007/s11356-017-9615-z. Epub 2017 Jul 7.
Gasification has gained advantage as an effective way to dispose domestic solid waste in mountainous rural of China. However, its toxic emissions such as PCDD/Fs and heavy metals, as well as their potential environmental risks, were not well studied in engineering application. In this study, an updraft fixed bed gasifier was investigated by field sampling analysis. Results showed that low toxic emissions (dust, SO, NOx, HCl, CO, HS, NH, PCDD/Fs and heavy metals) in the flue gas were achieved when the rural solid waste was used as feedstock. The mass distribution of heavy metals showed that 94.00% of Pb, 80.45% of Cu, 78.00% of Cd, 77.31% of Cr, and 76.25% of As were remained in residual, whereas 86.58% of Hg was found in flue gas. The content of PCDD/Fs in the flue gas was 0.103 ngI-TEQ·Nm, and the total emission factor of PCDD/Fs from the gasifier was 50.04 μgI-TEQ·t-waste, among which only 0.04 μgI-TEQ·t-waste was found in the flue gas. The total output of PCDD/Fs was1.89 times as high as input, indicting the updraft fixed bed gasifier increased emission of PCDD/Fs during the treatment domestic solid waste. In addition, the distribution characteristics of PCDD/Fs congeners reflected that PCDD/Fs was mainly generated in the gasification process rather than the stage of flue gas cleaning, suggesting the importance to effectively control the generation of PCDD/Fs within the gasifier chamber in order to obtain a low PCDD/Fs emission level.
气化作为一种有效的方法，在中国山区农村处理生活垃圾方面具有优势。然而，其有毒排放物，如 PCDD/Fs 和重金属，以及它们的潜在环境风险，在工程应用中并没有得到很好的研究。在本研究中，通过野外采样分析对上吸式固定床气化炉进行了研究。结果表明，当农村固体废物作为原料时，烟道气中的低毒性排放物（粉尘、SO、NOx、HCl、CO、HS、NH、PCDD/Fs 和重金属）得以实现。重金属的质量分布表明，94.00%的 Pb、80.45%的 Cu、78.00%的 Cd、77.31%的 Cr 和 76.25%的 As 残留在残余物中，而 86.58%的 Hg 则存在于烟道气中。烟道气中的 PCDD/Fs 含量为 0.103 ngI-TEQ·Nm，气化炉的 PCDD/Fs 总排放因子为 50.04μgI-TEQ·t-废物，其中仅在烟道气中发现 0.04μgI-TEQ·t-废物。PCDD/Fs 的总排放量是输入量的 1.89 倍，表明上吸式固定床气化炉在处理生活垃圾过程中增加了 PCDD/Fs 的排放。此外，PCDD/Fs 同系物的分布特征表明，PCDD/Fs 主要是在气化过程中产生的，而不是在烟道气净化阶段，这表明为了获得低 PCDD/Fs 排放水平，必须有效地控制气化炉室内 PCDD/Fs 的生成。
