Chemical speciation of carbon in municipal solid waste incinerator residues

Abstract

Incinerators do not achieve a complete mineralization of organic constituents of municipal solid waste. The solid residues (bottom ash, boiler ash and air pollution control residues) contain carbon which can be determined as total organic carbon (TOC). This work focuses on the TOC composition and its significance to the genesis and diagenesis of the solid residues. An analytical procedure is presented to characterize carbon species by different chemical and microscopic analytical methods. The procedure is based on two steps. In the first step a quantitative classification of TOC into four different carbon species (elemental carbon, water extractable organic carbon, dichloromethane extractable organic carbon and non extractable organic carbon) is performed to obtain a first survey of the TOC composition. Based on this survey a further characterization of individual carbon species is performed. The results of the qualitative and quantitative characterization of carbon species allow to postulate hypotheses on the influence of organic carbon on the long-term behavior of the solid residues.

Characterization of air pollution control residues produced in a municipal solid waste incinerator in Portugal

“…It is important to note that the elemental analysis does not give indication about the chemical species in which the carbon is involved. Even if it is clear from the literature that one of the main concerns is related to dioxins and furans [69][70][71][72][73][74], other studies refer that more than 600 organic micropollutants were identified [80]. In our study, the total carbon content for sample A5 is 2.84% (Table 4) and according to a preliminary analysis, only 35.6% of the total carbon content is organic and 64.4% may be in inorganic forms (carbonates).…”

“…In fact, the results showed that only 0.4% of the carbon in the solid phase may be dissolved, and through a TOC analysis (5000A-Shimadzu) it was observed that only 56.9 mg/kg of organic carbon and 53.3 mg/kg of inorganic carbon were dissolved. For a comprehensive analysis in order to determine the carbon speciation, several analytical techniques may be used in a complementary way to the elemental analysis, such as mass spectroscopy, FTIR, thermogravimetric analysis and GC-MS [80]. Table 5 shows the values obtained for the total availability for Pb, Cd, Zn, Cr, Ni, Cu, K, Na, Fe, Al, Si and Cl − concerning samples A1-A5, as well as the ratio TA/TC.…”

Temperature and pH Dependence of Some Metals Leaching from Fly Ash of Municipal Solid Waste

“…Since combustion of organic matter in the incinerator is never complete, variety of organic compounds, although in low concentration, can be detected in fly ash samples (Ferrari et al, 2002). In our samples, organic carbon content varied from 1.8 to 4.1 % of fly ash by weight.…”

Chemical extraction of organic carbon to reduce the leaching potential risk from MSWI bottom ash

“…Total carbon can be qualitatively divided into two frac- tions [29]: organic carbon (OC) and carbonate carbon (CC). Highest efficiency of acid extraction for TC extraction would be mainly attributed to higher extraction of CC by neutralization of carbonates in bottom ash, controlled by buffering reactions [30].…”

“…The extraction by HCl showed the highest reduction of DOC leaching potential at pH 7. Ferrari et al [29] also found that the majority of organic carbon in bottom ash cannot be extracted either by water or alkaline solution. Zhang et al [21] also used water for evaluation of extractable organic carbon fraction in bottom ash.…”