MSW pyrolysis volatiles' reforming by incineration fly ash for both pyrolysis products upgrading and fly ash stabilization. (February 2023)

• Record Type: Journal Article
• Authors: Tang, Yuzhen; Chen, Dezhen; Feng, Yuheng; Hu, Yuyan; Yin, Lijie; Qian, Kezhen; Yuan, Guoan; Zhang, Ruina
• Is Part Of: Chemosphere. Volume 313(2023)
• Publication Date: 2023-02
• Subjects: Municipal solid wastes (MSW) -- Pyrolysis volatiles -- Incineration fly ash (IFA) -- Catalytic reforming -- Chloride -- Heavy metals (HMs); Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2022.137536
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: The effective disposal of municipal solid wastes (MSW) and its incineration-derived fly ash (IFA), which contains large amounts of heavy metals (HMs) and chlorine (Cl), is an urgent task. In this study, IFA was used to reform MSW pyrolysis volatiles within 500–800 °C. The changes of reformed pyrolysis products, the migration characteristics of HMs and Cl between IFA and pyrolysis products were investigated. The results indicated that the O- and Cl-containing compounds in pyrolysis oil tended to decrease, light hydrocarbons and its calorific value increased accordingly after reforming; more CH4 and H2 gases were produced concurrently. The increase in reforming temperature enhanced these trends. The IFA absorbed Cl from volatiles during reforming, which reduced HCl in the gas product. The toxicity equivalent (TEQ) of PCDD/Fs in IFA decreased dramatically from 0.47 μg/kg to 0.0055 μg/kg after reforming at 500 °C, and it decreased with increasing reforming temperature. Some of the HMs' concentrations in the used IFAs increased, but their leaching capacity all decreased significantly at 800 °C except for Cr. The used IFA at 800 °C (IFA-800) corresponded to the lowest HMs leaching concentrations and could meet the landfill requirements; while the used IFA at 500 °C (IFA-500) corresponded to the maximum carbon deposition of 14.63 wt%, providing the energy source for its melting. Therefore 800 °C was recommended for harmless disposal of IFA, and 500 °C was better for a further melting of IFA., The contamination of pyrolysis liquid caused by inorganic Cl-containing compounds at 500 and 800 °C with much lower levels than the original. This study showed the hazardous properties of IFA can be dampened after interacting with MSW pyrolysis volatiles within the tested temperature range, and provided a good chance for the simultaneous disposal of IFA and recovery of high-quality MSW pyrolysis products. Graphical abstract: Image 1 Highlights: IFA used to reform MSW pyrolysis volatiles and being stabilized simultaneously. The reforming caused 5.20–14.65 wt% of carbon deposition on the used IFAs. Cl transferred from volatiles to IFA after reforming, but PCDD/Fs in IFA decreased. The HMs leaching capability of IFA-800 reduced dramatically except for Cr. 800 °C recommended for IFA stabilization and 500 °C recommended for IFA melting.