Detoxification of municipal solid waste incinerator (MSWI) fly ash by single-mode microwave (MW) irradiation: Addition of urea on the degradation of Dioxin and mechanism.

Affiliation

South China Institute of Environmental Sciences, Ministry of Environmental Protection (MEP), Guangzhou 510655, PR China; Innovative Laboratory for Environmental Functional Materials and Environmental Applications of Microwave Irradiation, South China Subcenter of State Environmental Dioxin Monitoring Center, Ministry of Environmental Protection (MEP), Guangzhou 510655, PR China; Guangdong Key Laboratory of Water and Air Pollution Control, Guangzhou 510655, PR China. Electronic address: [Email]

Abstract

The detoxification of municipal solid waste incinerator (MSWI) fly ash dioxins urgently requires an effective treatment technology. In this study, we adopted a single-mode microwave (MW)-based pyrolysis to treat MSWI fly ash under N2 atmosphere and further elucidated the main influencing factors, including the chemical inhibitor, for dioxin control. The results show that (1) the detoxification process was optimized with a mass ratio of fly ash to SiC of 1:9, 23.1% (wt%) urea addition and pyrolysis temperature of ˜ 480 °C; (2) the total polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) destruction efficiency and the bioassay-derived 2,3,7,8-TCDD toxic equivalent (Bio-TEQ) removal efficiency reached 98.5% and 97.9%, respectively, accompanied with ˜ 1.3% of the total amount of dioxin being submitted to exhaust gas; (3) the MW-based pyrolysis of urea (133˜300 °C) was favourable for the generation of hot spots as well as the PCDD/F rapid destruction in fly ash. In addition, the leaching toxicity of heavy metals was also partially reduced after MW pyrolysis reactions. To the best of our knowledge, this is the first report adopting a MW-based pyrolysis to eliminate dioxin in MSWI fly ash with the addition of urea, which is a promising alternative to current methods.

Keywords

Dechlorination,Fly ash,Hot spots,Microwave,Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs),

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