Department of Energy and Resources Engineering, College of Engineering, Peking University, Beijing 100871, People's Republic of China.
Department of Energy and Resources Engineering, College of Engineering, Peking University, Beijing 100871, People's Republic of China; School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China.
Waste Manag. 2018 Oct;80:175-185. doi: 10.1016/j.wasman.2018.09.012. Epub 2018 Sep 12.
Inherent minerals in sludge influence sludge pyrolysis behaviors and the final products. In this study, the effects of inherent minerals on sewage sludge pyrolysis were systematically investigated by studying the pyrolysis behaviors of raw sewage sludge (RS) and HCl-washed sludge (WS), and in combination with thermodynamic equilibrium simulations for the hypothetical mineral-free sludge (AS) assumed. The pyrolysis of RS and WS was performed with a novel online thermogravimetric analyzer equipped with an infrared spectrometer and a gas chromatograph coupled with a mass spectrometer (TG-IR-GC/MS). It was found that inherent minerals influenced both the release of volatile products as a function of pyrolysis temperature, and the development of the physicochemical properties of the derived char. In the temperature range of 300-500 °C, hydrocarbons with more than 4 carbon atoms as well as aromatic compounds showed an increased release during WS pyrolysis, with respect to RS, while hydrocarbons with less than 3 carbon atoms such as CH and CH exhibited a decreased release. In addition, the inherent minerals enhanced the release of HCN and NH, both leading to increased NO release, and the release of HS and COS was also promoted while the release of CHSH, SO and CS was mitigated. Kinetic analysis confirmed that a catalytic effect induced by the inherent minerals decreased the activation energy at 300-500 °C. Thermodynamic simulations suggested that inherent minerals influenced sludge pyrolysis and the derived products formation by increasing the total Gibbs energy of the sludge pyrolysis system. Therefore, considerations of sludge inherent minerals should be taken into account during pyrolysis for the purpose of value-added commodity production and pollutant mitigation.
污泥中的固有矿物质会影响污泥热解行为和最终产物。在这项研究中，通过研究原状污泥 (RS) 和 HCl 洗涤污泥 (WS) 的热解行为，并结合对假定无矿物质的假想污泥 (AS) 的热力学平衡模拟，系统地研究了固有矿物质对污水污泥热解的影响。采用配备红外光谱仪和气相色谱仪与质谱仪 (TG-IR-GC/MS) 的新型在线热重分析仪对 RS 和 WS 进行热解。结果发现，固有矿物质不仅影响挥发性产物随热解温度的释放，还影响衍生焦的物理化学性质的发展。在 300-500°C 的温度范围内，与 RS 相比，WS 热解过程中释放出更多的 4 个以上碳原子的烃类和芳香族化合物，而 CH 和 CH 等少于 3 个碳原子的烃类则减少释放。此外，固有矿物质促进了 HCN 和 NH 的释放，这两种物质都会导致 NO 释放增加，同时也促进了 HS 和 COS 的释放，而 CHSH、SO 和 CS 的释放则受到抑制。动力学分析证实，固有矿物质引起的催化作用降低了 300-500°C 时的活化能。热力学模拟表明，固有矿物质通过增加污泥热解系统的总吉布斯能来影响污泥热解和衍生产物的形成。因此，在进行热解以实现增值商品生产和减少污染物排放时，应考虑污泥中的固有矿物质。
