Short Communication Fate of polycyclic aromatic hydrocarbons during vitrification of incinerator ash in a coke bed furnace Yi-Ming Kuo a , Ta-Chang Lin a, * , Perng-Jy Tsai b , Wen-Jhy Lee a , Hsin-Yi Lin c a Department of Environmental Engineering, National Cheng Kung University, 1, University Road, Tainan 70101, Taiwan, ROC b Graduate Institute of Environmental and Occupational Health, Medical College, National Cheng Kung University, 138, Sheng-Li Road, Tainan 70428, Taiwan, ROC c Department of Occupational Safety and Health, Chang Jung Christian University, 396, Sec. 1, Chang Jung Road, Kway Jen, Tainan 711, Taiwan, ROC Received 27 May 2002; received in revised form 9 December 2002; accepted 9 December 2002 Abstract Fate of polycyclic aromatic hydrocarbons (PAHs) during the vitrification of fly ash and bottom ash from the municipal waste incinerator in a coke bed furnace was investigated. In this system, both coke and lime were added to enhance the melting reaction. The major PAH sources in this system were ash and coke, which respectively contributed 97% and 3% of PAHs in the input-mass. During vitrification process, low molecular PAHs (LM-PAH, 2–3-ring), median molecular PAHs (MM-PAH, 4-ring) and high molecular PAHs (HM-PAH, 5–7-ring) mass respectively ac- counted for >99%, >99% and 84% of the output-mass emitted as the stack flue gas; while those discharged from the slagwere <1%, <1%and16%,respectively.TheO/I(output-mass/input-mass)ratioofLM-,MM-andHM-PAHswere 0.063, 0.002 and <0.001, respectively. The high distribution in flue gas and O/I ratio of LM-PAHs is reasonable since they are more easily evaporated, hence difficult to be removed by air pollution control devices. On the contrary, the HM-PAHs, having lower vapor pressure, primarily stays mainly in slag. Based on the 21 total PAH content in feeding ashandslag,thereductionefficiencyofthecokebedfurnacewas >99.9%. To minimize the risk of secondary pollution, the efficiency of coke bed furnace should be improved to reduce the PAH emission into ambient air. Ó 2002 Elsevier Science Ltd. All rights reserved. Keywords: PAHs; Coke bed furnace; Slag; Ash; Melting 1. Introduction Confrontingtherapidgrowthofmunicipalwaste,the strategy of combining incineration and landfill disposal has been practiced globally. However, products gener- ated during incineration process, including flue gas and ash, could lead to secondary pollutions. Stringent reg- ulations have been enforced to control flue gas for de- cades, but the treatment of residue was usually ignored. Recent research has shown that ash carries 80–90% of the total dioxins emission (Abe et al., 1997). Melting process, generally classified by heat sources as electric or fuel-burning types, can lead to a volume reduction (Kinto, 1996), a destruction of >98% of dioxins (as TEQ) (Ito, 1996), and metals can be separated for smelting by phase separation (Ecke et al., 2000). The mobility potential of hazardous metal in slag is drasti- callyreducedconcurrently(Eckeetal.,2001).Therefore, the benefit is quite conspicuous if the ash melting pro- cess could be implemented extensively. Dioxin content in ash was the common focus in research (Abad et al., Chemosphere 51 (2003) 313–319 www.elsevier.com/locate/chemosphere * Corresponding author. Tel.: +886-6-2757575x65829; fax: +886-6-2752790. E-mail address: tachang@mail.ncku.edu.tw (T.-C. Lin). 0045-6535/03/$ - see front matter Ó 2002 Elsevier Science Ltd. All rights reserved. doi:10.1016/S0045-6535(02)00852-4