A novel integrated method for ultrasonic-assisted MSWI fly ash decarbonization with PCDD/Fs detoxification and synergistic heavy metals stabilization

Jie Chen; Congkai Fu; Xiaoqing Lin; Xiaodong Li; Jianhua Yan

doi:10.1016/j.envpol.2025.126267

A novel integrated method for ultrasonic-assisted MSWI fly ash decarbonization with PCDD/Fs detoxification and synergistic heavy metals stabilization

Environ Pollut. 2025 Jun 1:374:126267. doi: 10.1016/j.envpol.2025.126267. Epub 2025 Apr 17.

Authors

Jie Chen¹, Congkai Fu¹, Xiaoqing Lin², Xiaodong Li¹, Jianhua Yan³

Affiliations

¹ State Key Laboratory of Clean Energy Utilization, Institute of Thermal Power Engineering of Zhejiang University, Hangzhou, 310027, Zhejiang, China.
² State Key Laboratory of Clean Energy Utilization, Institute of Thermal Power Engineering of Zhejiang University, Hangzhou, 310027, Zhejiang, China. Electronic address: linxiaoqing@zju.edu.cn.
³ State Key Laboratory of Clean Energy Utilization, Institute of Thermal Power Engineering of Zhejiang University, Hangzhou, 310027, Zhejiang, China. Electronic address: yanjh@zju.edu.cn.

PMID: 40250518
DOI: 10.1016/j.envpol.2025.126267

Abstract

A novel ultrasonic-assisted flotation method was developed to enhance the harmless treatment and resource utilization of municipal solid waste incineration fly ash (MSWI FA). This study examined ultrasound effects on collector (kerosene) and frother (2-octanol) emulsification and its role in flotation decarbonization. Additionally, the mechanism of PCDD/Fs detoxification and heavy metals migration and stabilization were revealed. The results indicated that ultrasonic emulsification significantly improved the collector dispersibility, while optimizing ultrasonic duration and power reduced emulsion droplets size and enhanced the collector adsorption capacity on carbon particles. Under optimal conditions (280 W_10 min), ultrasonic flotation effectively disintegrated agglomerated FA, increased carbon particle exposure, and enhanced decarbonization efficiency to 46.3 %. Meanwhile, ultrasound flotation enhanced NaCl and KCl dissolution, lowering Cl content in residue fly ash (ReFA) to below 2 %. PCDD/Fs were primarily enriched in activated carbon and transferred into the flotation FA (FFA), leading to a 48.9 % reduction in the toxic equivalent of PCDD/Fs in ReFA. Compared to FFA, ReFA exhibited a higher content of high-chlorinated PCDD/Fs, particularly 1,2,3,4,6,7,8-HpCDD, OCDD, 1,2,3,4,6,7,8-HpCDF, and OCDF. This distribution was likely attributed to the different selective adsorption behavior of activated carbon and calcium oxide (CaO). With the addition of 0.5 % Na₂S, the Pb leaching concentration was significantly reduced to 0.01 mg/L. In conclusion, this technology simultaneously achieved dechlorination, decarbonization, PCDD/Fs detoxification, and heavy metal stabilization, offering a low-carbon and energy-efficient FA treatment method.

Keywords: Decarbonization; Flotation; Heavy metals; MSWI fly ash; PCDD/Fs; Ultrasound.

MeSH terms

Adsorption
Benzofurans* / analysis
Benzofurans* / chemistry
Coal Ash* / analysis
Coal Ash* / chemistry
Dibenzofurans, Polychlorinated
Incineration* / methods
Metals, Heavy* / analysis
Metals, Heavy* / chemistry
Polychlorinated Dibenzodioxins / analysis
Polychlorinated Dibenzodioxins / chemistry

Substances

Coal Ash
Metals, Heavy
Polychlorinated Dibenzodioxins
Benzofurans
Dibenzofurans, Polychlorinated