The effects of temperature and oxygen content on the PCDD/PCDFs formation in MSW fly ash

Chang, Moo Been; Huang, Tsai Fei

doi:10.1016/s0045-6535(99)00227-1

Cited by 66 publications

(25 citation statements)

References 14 publications

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“…In most of the previous reports on evaluation of gasification behavior of PCDD/Fs in fly ash by thermal treatment, an ash sample was placed on a heating boat [25,26] or was packed in a heating tube [22,23]. As fly ash has low thermal conductivity, an excess of sample amount may result in insufficient thermal action into the sample irrespective of the method employed.…”

Section: Treated Amount Of Ash and Air Flow Ratementioning

confidence: 99%

Evaluation of gas-particle partition of dioxins in flue gas I: Evaluation of gasification behavior of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in fly ash by thermal treatment

Yokohama

Otaka

Minato

et al. 2008

Journal of Hazardous Materials

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Section: Treated Amount Of Ash and Air Flow Ratementioning

confidence: 99%

Evaluation of gas-particle partition of dioxins in flue gas I: Evaluation of gasification behavior of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in fly ash by thermal treatment

Yokohama

Otaka

Minato

et al. 2008

Journal of Hazardous Materials

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“…In general, two Fig. 5 The composition of PCDD/Fs isomers in soil and gas Environ Sci Pollut Res mechanisms have been raised primarily to explain the synthesis of dioxins: the precursor mechanism and the de novo synthesis (Schoonenboom and Olie 1995;Chang and Huang 2000). The precursor mechanism is the formation from (gas phase) intermediates such as chlorophenols, chlorobenzenes or chlorinated biphenyls (Weber and Hagenmaier 1999).…”

Section: Pcdd/fs Concentration and Teq In Gasmentioning

confidence: 99%

Effect of oxygen content on the thermal desorption of polychlorinated biphenyl-contaminated soil

Liu

et al. 2015

Environ Sci Pollut Res

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Oxygen plays an important role during the thermal treatment of soil, contaminated with polychlorinated biphenyls (PCBs), due to the potential oxidation of PCBs to form polychlorinated dibenzofurans (PCDFs). The effect of oxygen content (0, 5, 21 and 100%) in carrier gases on PCBs and PCDD/Fs was studied both in soil and gas after thermal desorption of PCBs contaminated soil at 500 °C. All 209 congeners of PCBs and 136 congeners of PCDD/Fs (P = 4 to 8) were analysed. Oxygen content showed little effect on PCB removal and destruction. Under different carrier gases, the removal efficiency and the destruction efficiency for PCBs attained 93.8-95.5 and 83.0-85.0 %, respectively. The levels of PCDD/Fs in soil and gas were correlated positively with oxygen content. Compared with PCDDs, PCDFs in soil were not effectively removed under oxidative conditions because there was chemistry going on and PCBs were being converted to PCDFs. The total concentration of PCDFs in soil and gas was 2.6, 11.3, 15.6 and 17.5 times of the initial PCDFs concentration (21.9 ng/g) in raw soil with increasing oxygen content. Thus, substantial amounts of PCDFs were generated in the presence of oxygen during the treatment of contaminated soil.

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“…In the same way, both the PCDD/Fs concentration and I-TEQ value increased after treatment for 90 min, which was the distribution of OCDD in the gas phase. Chang et al [11] studied the effect of oxygen content on the PCDD/Fs formation in MSW fly ash. Their results showed that trace amounts of PCDD/Fs were also found in the fly ash even when pure nitrogen was passing through it.…”

Section: Effect Of Thermal Treatment Time On Pcdd/fs Concentration Anmentioning

confidence: 99%

Experimental study on low temperature thermal treatment of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in fly ash

Yan

Chen

et al. 2007

Front. Energy Power Eng. China

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Spanish MSW incinerator indicated that PCDD/Fs levels in flue gas constituted a minor contribution to the total PCDD/ Fs emission. The highest concentration of PCDD/Fs was found in fly ash. The second highest concentration of PCDD/ Fs was found in slag [5]. The I-TEQ value of PCDD/Fs in fly ash produced from different types of incinerators in China was in the range of 242-7 530 ng/kg, which was lower than that of other countries. The level of concern of PCDD/Fs in fly ash was commonly referred to that of the resident soil. For example, the level is 1 000 ng TEQ/kg in Japan [6]. Although the fly ash produced from MSW incineration must be treated as hazardous waste, until now, there have been no regulations for PCDD/Fs level in fly ash in China.Stieglitz et al. demonstrated that PCDD/Fs in fly ash could be decomposed by thermal treatment under suitable conditions. On the one hand, thermal treatment of fly ash at 600 °C for 2 h resulted in about 95% decomposition of PCDD/Fs under an oxidation atmosphere, but at lower temperatures, PCDD/ Fs were reformed. On the other hand, thermal treatment of fly ash at 300 °C for 2 h resulted in about 90% decomposition of PCDD/Fs under an inert atmosphere [7]. The results of thermal treatment of fly ash produced from a fluidized bed incinerator showed that PCDD/Fs in fly ash could be decomposed by about 77% at 1 100 °C for 0.5 h. However, PCDD/Fs would be reformed in the flue gas although PCDD/ Fs in fly ash could be decomposed at a temperature lower than 1 100 °C (800-1 000 °C) [8].In this study, the effects of temperature and time on PCDD/ Fs distribution in the fly ash of an MSW incinerator were investigated in a tubular oven under nitrogen atmosphere, which could provide technical data for PCDD/Fs decomposition in fly ash. Experimental Experimental apparatus and conditionsFly ash was collected from the bag filter of a hydraulic ladder mechanical grate-fired MSW incinerator, whose capacity is Abstract The effects of temperature and time on polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) distribution in fly ash of a municipal solid waste incinerator (MSWI) were studied in a tubular oven under nitrogen atmosphere. The PCDD/Fs in the gas phase and solid phase were detected by high-resolution gas chromatography coupled with low resolution mass spectrometry (HRGC/LRMS) se para tely. The experimental results showed that the major congener was octa-chlorinated dibenzo-p-dioxin (OCDD) in the gas phase and the low chlorinated congeners were the major products in the solid phase. There were high levels of OCDD in the gas phase in several experimental conditions although the PCDD/Fs in the solid phase could be decomposed. The optimum condition for PCDD/Fs decomposition in fly ash was a heating time of 60 min at 400 °C under nitrogen atmosphere.

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The effects of temperature and oxygen content on the PCDD/PCDFs formation in MSW fly ash

Cited by 66 publications

References 14 publications

Evaluation of gas-particle partition of dioxins in flue gas I: Evaluation of gasification behavior of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in fly ash by thermal treatment

Evaluation of gas-particle partition of dioxins in flue gas I: Evaluation of gasification behavior of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in fly ash by thermal treatment

Effect of oxygen content on the thermal desorption of polychlorinated biphenyl-contaminated soil

Experimental study on low temperature thermal treatment of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in fly ash

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