Invited paper Metals leachability from medical waste incinerator fly ash: A case study on particle size comparison Sukandar Sukandar a, * , Kenji Yasuda a , Masaru Tanaka a , Isao Aoyama b a Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima, Naka, Okayama City, Okayama 700-8530, Japan b Research Institute for Bioresources, Okayama University, 2-20-1 Chuo, Kurashiki City, Okayama 710-0046, Japan Received 29 August 2005; received in revised form 6 January 2006; accepted 8 February 2006 As, Cd, Cr, Ni, Pb, Sn and Zn in particle size fraction of 150e106 mm of the medical waste fly ash tended to bind to FeeMn oxide phase. Abstract This paper presents the results from a study of metals leachability of medical waste incinerator fly ash in Japan on the basis of particle size. Sequential extraction and Toxicity Characteristic Leaching Procedure (TCLP) analysis were carried out in order to quantify the leaching amount of metals in each categorized particle size. Sequential extraction was also subjected to identify the preference of binding matrix of metals. The results of sequential extraction showed an increase both exchangeable and carbonate associated chromium concentrations in the bigger particle size fractions. Likewise, concentrations of carbonate matrix of arsenic and tin tended to increase in the bigger particle size fractions. In contrast, exchangeable associated cadmium as well as both exchangeable and carbonate matrices of barium were found higher in the smaller particle size fractions. However, no correlation was found in Kendal-tau correlation analysis between particle size of the ash and metals leachability of the TCLP. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Fly ash; Particle size; Metals leachability; Binding matrix; Medical waste 1. Introduction The term of medical waste in Japan is all wastes including infectious waste disposed off from medical institutions (Miyazaki and Une, 2005). The management of infectious materials in Japan is regulated under the Waste Disposal Law of 2003. The Ministry of Environment revised new criteria for in- fectious waste in 2004. The new criteria defined infectious waste on the basis of form of waste, place of waste generation, and kind of infectious disease. Tanaka et al. (2004) estimated that the quantity of infectious waste deriving from medical establish- ments in Japan is 218,000 t/year, of which 82.3% is incinerated. Integrated solid waste management usually takes into con- sideration the properties of the waste in all stages. Identifica- tion of waste characteristics is conducted from the waste generation to intermediate treatment residues until disposed off in final disposal. Based on the characteristics of the waste, the appropriate treatment and disposal system is established to minimize the environmental impact. However, such stages cannot be applied for medical waste in Japan due to the strict regulation. Based on the regulation, all infectious materials are put into hermetically tight containers, and then placed in a spe- cial storage area not to be opened until incinerated. Hence, contrary to municipal solid waste, data regarding physico- chemical characteristics of medical waste in Japan are very scarce for at least one last decade. The latest data of the waste composition based on physical segregation was con- ducted in 1998, which was carried out in a hospital in Osaka (Yamaguchi et al., 2002). Thus, the data could not represent * Corresponding author. Tel./fax: +81 86 251 8840. E-mail addresses: dns15613@cc.okayama-u.ac.jp, sukandar2001@yahoo. com (S. Sukandar). 0269-7491/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.envpol.2006.02.010 Environmental Pollution 144 (2006) 726e735 www.elsevier.com/locate/envpol