W D Chanaka Udayanga, Veksha Andrei, Giannis Apostolos, Liang Yen Nan, Lisak Grzegorz, Hu Xiao, Lim Teik-Thye
Residues and Resource Reclamation Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One, Singapore 637141, Singapore; School of Civil and Environmental Engineering, Nanyang Technological University, Singapore 639798, Singapore; Interdisciplinary Graduate School, Nanyang Technological University, Singapore 639798, Singapore.
Residues and Resource Reclamation Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One, Singapore 637141, Singapore.
Sci Total Environ. 2019 Nov 15;691:232-242. doi: 10.1016/j.scitotenv.2019.07.095. Epub 2019 Jul 7.
The purpose of this study was to determine the mechanisms in heavy metals immobilisation during pyrolysis of industrial sludge (IS). Pyrolysis was conducted in a fixed-bed unit at the temperature range between 400 and 800°C. Conventional and advanced analytical techniques were employed to assess the influencing parameters on the transformation of heavy metals during pyrolysis process. The examined heavy metals (i.e. Mn, Ni, Cu, Zn, Cd, and Pb) were effectively immobilised in the char derived at ≤600°C. In contrast, for the char derived at ≥700°C, Mn, Cu, and Zn leaching efficiencies were significantly increased. According to BCR sequential extraction procedure (SEP) results, pyrolysis of IS conducted at ≤600°C transformed heavy metals into stable fractions (i.e. associated with Fe-Mn nodules, and organics and sulphides), while Mn, Cu, and Zn bound in these fractions decomposed into easily soluble forms at higher temperatures. Advanced analytical characterisation (XRD, EDX, XPS, and FTIR) of the derived char and anion concentrations in the leachate have demonstrated that the increase in metal leaching was probably due to the formation of metal halides.
本研究的目的是确定工业污泥（IS）热解过程中重金属固定的机制。热解在固定床装置中于400至800°C的温度范围内进行。采用常规和先进的分析技术来评估热解过程中影响重金属转化的参数。所检测的重金属（即锰、镍、铜、锌、镉和铅）在600°C及以下温度热解得到的焦炭中有效固定。相比之下，对于700°C及以上温度热解得到的焦炭，锰、铜和锌的浸出效率显著提高。根据BCR连续提取程序（SEP）的结果，600°C及以下温度进行的IS热解将重金属转化为稳定的形态（即与铁锰结核、有机物和硫化物结合），而在较高温度下，结合在这些形态中的锰、铜和锌分解为易溶形式。对热解得到的焦炭进行的先进分析表征（XRD、EDX、XPS和FTIR）以及渗滤液中的阴离子浓度表明，金属浸出增加可能是由于金属卤化物的形成。
