State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou, 310027, China.
State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou, 310027, China; Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
J Environ Manage. 2023 Aug 1;339:117938. doi: 10.1016/j.jenvman.2023.117938. Epub 2023 Apr 18.
Low-carbon and high-efficiency binder is desirable for sustainable treatment of municipal solid waste incineration fly ash (MSWI FA). In this study, CaO or MgO was used to activate ground granulated blast furnace slag (GGBS) to form calcium silicate hydrate and magnesium silica hydrate gel for stabilization/solidification of hazardous MSWI FA. Experimental results showed that potential toxic elements (PTEs), such as Pb and Zn, significantly inhibited the formation of reaction products in CaO-GGBS system due to the complexation between Ca(OH) and PTEs, whereas PTEs only had insignificant inhibition on transformation from MgO to Mg(OH) in MgO-GGBS system, resulting in lower leachabilities of PTEs and higher mechanical strengths. Stabilization/solidification experiments demonstrated that MSWI FA (70 wt%) could be recycled by MgO-GGBS binder (30 wt%) into blocks with desirable 28-day compressive strengths (3.9 MPa) and PTEs immobilization efficiencies (99.8% for Zn and 99.7% for Pb). This work provides mechanistic insights on the immobilization mechanisms of PTEs in CaO/MgO-GGBS systems and suggests a promising MgO-GGBS binder for low-carbon treatment of MSWI FA.
低碳、高效的粘结剂对于城市固体废物焚烧飞灰（MSWI FA）的可持续处理是理想的选择。在这项研究中，使用 CaO 或 MgO 来激活粒化高炉矿渣（GGBS），以形成硅酸钙水化物和镁硅水化物凝胶，用于稳定/固化危险的 MSWI FA。实验结果表明，潜在的有毒元素（PTEs），如 Pb 和 Zn，由于 Ca(OH)与 PTEs 的络合作用，显著抑制了 CaO-GGBS 体系中反应产物的形成，而 PTEs 对 MgO 向 Mg(OH)的转化只有轻微的抑制作用，导致 PTEs 的浸出率更低，机械强度更高。稳定/固化实验表明，通过将 30wt%的 MgO-GGBS 粘结剂与 70wt%的 MSWI FA 混合，可将 MSWI FA 制成块体，具有理想的 28 天抗压强度（3.9MPa）和 PTEs 固定效率（Zn 为 99.8%，Pb 为 99.7%）。这项工作为 CaO/MgO-GGBS 体系中 PTEs 的固定机制提供了机理上的见解，并为 MSWI FA 的低碳处理提出了一种有前途的 MgO-GGBS 粘结剂。
