Characterization of residual carbon influencing on de novo synthesis of PCDD/Fs in MSWI fly ash

Kakuta, Yoshitada; Matsuto, Toshihiko; Tojo, Yasumasa; Tomikawa, Hiroki

doi:10.1016/j.chemosphere.2007.02.017

Cited by 19 publications

(7 citation statements)

References 5 publications

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“…4), as also found in previous research (Wang et al, 2003c;Lee et al, 2004;Cavaliere et al, 2011;Chen et al, 2012;Esposito et al, 2014). The PCDDs/ PCDFs ratio were only 0.09 to 0.17, indicating that the PCDD/Fs could be formed by de novo synthesis when there were enough carbon sources and metallic catalyst (Kakuta et al, 2007;Ooi and Lu, 2011;Chin et al, 2012). The significantly different emissions raised doubts as to whether the routine short-term manual inspection process that is currently used (and which takes place once or twice per year) is sufficient enough to represent a whole year's emissions for a continuously operating process, such as sintering.…”

Section: Long-term Amesa (La) Samplingsupporting

confidence: 60%

Utilization and Improvement of the Adsorption Method for Sampling PCDD/Fs from a Sinter Plant

Wang

Lin

Chang-Chien

et al. 2015

Aerosol Air Qual. Res.

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In this work, the Adsorption Method for Sampling (AMESA) is developed to collect long-term samples of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from stacks. However, the variation of in duration might affect the analytical results due to the memory effect in the AMESA. This research is one of the very few reports of using AMESA in sinter plants. Eight long-term AMESA (LA) samples were collected, followed by 16 parallel short-term AMESA (SA) and manual (SM) samples. The LA reports good correlations (R = 0.82-0.83) between PCDD/F emissions and the recovery feedstock, which can be further used for emission reduction. However, the breakthrough effects of the highly chlorinated PCDD/Fs is in the range of 6-14% in LA samples, and these are further improved by increasing the glass wool and adsorbent (with higher specific surface area, lower pore size, and higher polarity) packing, and finally reduced to 5.17%. For the shortterm sampling, a maximum difference of 170% occurred between SA and SM, if the sampling strategy suddenly changed from LA to SA. The PCDD/F memory effect remained for the first 8 SA samples, with the dominant 1,2,3,4,6,7,8-HpCDD and OCDD. Therefore, five post-washings for the AMESA system took place to successfully reduce the PCDD/F residual mass to > 0.2% of a normal LA. Unfortunately, these residuals were still equal to 51.4% of a normal SA. Therefore, it is not suggested that AMESA replace the current manual sampling method without any modification. According to this study, both the breakthrough and memory effects could be inhibited. Finally, a new inspection system, including both AMESA and shortterm samples, is then proposed for improving the PCDD/F control strategy in Taiwan.

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Section: Long-term Amesa (La) Samplingsupporting

confidence: 60%

Utilization and Improvement of the Adsorption Method for Sampling PCDD/Fs from a Sinter Plant

Wang

Lin

Chang-Chien

et al. 2015

Aerosol Air Qual. Res.

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“…Yan et al (2007) found that carbon content in some of HSWI fly ash reached the range of 11.40-91.0% due to activated carbon injection. Both injected powder activated carbon and unburned carbon in solid waste were identified as the main carbon sources of fly ash (Kakuta et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Removal of carbon constituents from hospital solid waste incinerator fly ash by column flotation

2013

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Hospital solid waste incinerator (HSWI) fly ash contains a large number of carbon constituents including powder activated carbon and unburned carbon, which are the major source of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in fly ash. Therefore, the removal of carbon constituents could reduce PCDD/Fs in fly ash greatly. In this study, the effects of the main flotation parameters on the removal of carbon constituents were investigated, and the characteristics of the final product were evaluated. The results showed that loss on ignition (LOI) of fly ash increased from 11.1% to 31.6% during conditioning process. By optimizing the flotation parameters at slurry concentration 0.05 kg/l, kerosene dosage 12 kg/t, frother dosage 3 kg/t and air flow rate 0.06 m(3)/h, 92.7% of the carbon constituents were removed from the raw fly ash. Under these conditions, the froth product has LOI of 56.35% and calorific values of 12.5 MJ/kg, LOI in the tailings was below 5%, and the total toxic equivalent (TEQ) of PCDD/Fs decreased from 5.61 ng-TEQ/g in the raw fly ash to 1.47 ng-TEQ/g in the tailings. The results show that column flotation is a potential technology for simultaneous separation of carbon constituents and PCDD/Fs from HSWI fly ash.

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“…With the continuous studying, three known PCDD/Fs formation mechanisms were found for PCDD/Fs in stack flue gases; (i) PCDD/Fs originally present in the feedstock of MSWIs; (ii) from precursor compounds in the MSW feed; (iii) from de novo synthesis of relatively innocuous chemical molecules combining together to form dioxins (McKay, 2002). However, the favourable temperature range of de novo synthesis is 250°C-400°C, and can be negligible when fly ash was heated at 400°C or higher temperature (Kakuta et al, 2007;Chen et al, 2008). Chlorine, although it is not a precursor of PCDD/Fs, was found to predominate the forming tendency toward debenzo-p-dioxins (PCDDs) or dibenzofurans (PCDFs) with a 0.8-1.1% threshold in the wastes (Wang et al, 2002).…”

Section: Introdutionmentioning

confidence: 99%

The Emission and Distribution of PCDD/Fs in Municipal Solid Waste Incinerators and Coal-fired Power Plant

Lin

et al. 2010

Aerosol Air Qual. Res.

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The emission and distribution of polychlorinated debenzo-p-dioxins/dibenzofurans (PCDD/Fs) was investigated in two municipal solid waste incinerators (MSWIs) and one coal-fired power plant (PP) in southern Taiwan. Samples were collected from stack flue gases (SFG), bottom residues (BR), super heater (SH), economizer (EC), semi-dry absorber (SDA), bag filter (BF), and fly ash pit (FAP) in MSWIs. Stack flue gases, bottom residues and electrostatic dust collectors (ESD) in PP were also collected. In order to compare the difference between the results of MSWIs and PP, samples from SFG, BS, and FAP in a PP were also determined. Seventeen congeners of PCDD/Fs were analyzed by utilizing a highresolution gas chromatograph/high-resolution mass spectrometer (HRGC/HRMS). Distributions of total PCDD/F-I-TEQ in each unit of MSWI-A and MSWI-B were SFG (0.3%, 0.07%), BR (3.9%, 0.62%), SH (0.17%, 0.24%), EC (4.2%, 0.05%), SDA (1.29%, 7.06%), and BF (90.14%, 91.97%), respectively. However, those in SFG, BS, and FAP of PP were 99.58%, 0.17%, and 0.25%, respectively. The above results indicated 99.5% PCDD/Fs were trapped in the fly ash of MWSI. On the other hand, 99.7% PCDD/Fs was emitted to the atmosphere from PP. The results of this study provide useful information for controlling PCDD/Fs in MSWIs and PP.

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Characterization of residual carbon influencing on de novo synthesis of PCDD/Fs in MSWI fly ash

Cited by 19 publications

References 5 publications

Utilization and Improvement of the Adsorption Method for Sampling PCDD/Fs from a Sinter Plant

Utilization and Improvement of the Adsorption Method for Sampling PCDD/Fs from a Sinter Plant

Removal of carbon constituents from hospital solid waste incinerator fly ash by column flotation

The Emission and Distribution of PCDD/Fs in Municipal Solid Waste Incinerators and Coal-fired Power Plant

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