Available online at www.sciencedirect.com Journal of Hazardous Materials 155 (2008) 179–182 Dioxin levels in ﬂy ash coming from the combustion of bagasse Nee Sun Choong Kwet Yive ∗ , Megalei Tiroumalechetty Department of Chemistry, University of Mauritius, R´ eduit, Mauritius Received 6 September 2006; received in revised form 11 October 2007; accepted 14 November 2007 Available online 22 November 2007 Abstract Levels of dioxins (PCDD/Fs) were determined in ﬂy ash samples collected from a power plant burning bagasse for production of electricity. The concentrations ranged from 2.2 pgWHO-TEQ/g to 190 pg WHO-TEQ/g with samples collected after ESP containing signiﬁcantly much higher (more than 12 times on average) levels than samples collected before ESP. Our results seem to indicate that both the de novo and the precursor mechanisms are signiﬁcantly involved in the formation of dioxins the ﬂy ash during combustion of bagasse. © 2007 Elsevier B.V. All rights reserved. Keywords: Dioxins; Bagasse; Combustion; Emission factors 1. Introduction Polychlorinated dibenzo-p-dioxins (PCDDs) and poly- chlorinated dibenzofurans (PCDFs), also known as dioxins (PCDD/Fs), are unintentionally produced chemicals that are toxic and persistent in the environment once released, and travel long distances. These two chemicals together with 10 others (9 organochlorine pesticides and 1 industrial chemical) have been classiﬁed as Persistent Organic Pollutants (POPs) and are soundly managed on a global level by the Stockholm Conven- tion. Countries, presently more than 150 [1], parties to this Con- vention have amongst their obligations the need to carry out an inventory of all activities responsible for the release of PCDD/Fs and also to make an annual estimate of PCDD/Fs release from these sources. To help countries in this exercise, United Nations Environment Programme (UNEP) has developed a guidance document [2] (that will be referred to as the toolkit) in which are compiled all activities likely to release PCDD/Fs together with the respective default emission factors. These PCDD/Fs default emission factors have been devised from published research ∗ Corresponding author. Tel.: +230 4541041; fax: +230 4656928. E-mail address: Robert@uom.ac.mu (N.S. Choong Kwet Yive). data. However, for some categories no proper emission factors are reported in the toolkit. For example, in the case of power generation from the combustion of biomass, emission factors are proposed for many biomasses including clean wood and various agricultural residues but not for bagasse, which is a residue left after the processing of sugarcane. Generally, huge amounts of bagasse are produced during the manufacturing of sugar from sugarcane and this represents a signiﬁcant source of biomass that can be used for the production of electricity and steam. For example, in Mauritius an estimated 1.5 mil- lion tonnes of bagasse is produced for an annual production of about 500,000 tonnes of sugar, and most of this bagasse is used to generate power or steam. It is worthy to note that more than 20% of the total electricity produced annually in Mau- ritius is generated from the combustion of bagasse. Thus, in sugar producing countries like Mauritius, the combustion of bagasse for power generation may constitute a major source of PCDD/Fs release. As emission factors for the combustion of bagasse are not given in the toolkit, it is therefore difﬁcult for these countries to properly estimate the release of PCDD/Fs from this activity. Furthermore, to our knowledge no data are available on the levels of PCDD/Fs in ﬂy ash coming from the combustion of bagasse. The main aim of this study was to determine levels of PCDD/Fs in ﬂy ash formed during bagasse combustion. 0304-3894/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.jhazmat.2007.11.045