Detoxifying PCDD/Fs and heavy metals in fly ash from medical waste incinerators with a DC double arc plasma torch

• Published in: Journal of environmental sciences (China) 2013-07, Vol.25 (7), p.1362-1367
• Main Authors: Pan, Xinchao, Yan, Jianhua, Xie, Zhengmiao
• Format: Article
• Language: English
• Subjects: Direct current; Fly ash; heavy metal; Heavy metals; Incinerators; Leaching; medical waste incinerator; Melting; microstructure; PCDD/Fs; plasma torch; polychlorinated dibenzodioxins; polychlorinated dibenzofurans; Slags; Toxic; toxicity; United States Environmental Protection Agency; wastes
• ISSN: 1001-0742; 1878-7320; 1001-0742
• DOI: 10.1016/S1001-0742(12)60196-X

Medical waste incinerator (MWI) fly ash is regarded as a highly toxic waste because it contains high concentrations of heavy metals and dioxins, including polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). Therefore fly ash from MWI must be appropriately treated before being discharged into the environment. A melting process based on a direct current thermal plasma torch has been developed to convert MWI fly ash into harmless slag. The leaching characteristics of heavy metals in fly ash and vitrified slag were investigated using the toxicity characteristic leaching procedure, while the content of PCDD/Fs in the fly ashes and slags was measured using method 1613 of the US EPA. The experimental results show that the decomposition rate of PCDD/Fs is over 99% in toxic equivalent quantity value and the leaching of heavy metals in the slag significantly decreases after the plasma melting process. The produced slag has a compact and homogeneous microstructure with density of up to 2.8 g/cm3.