It is of huge importance for sustainability to find a pragmatic solution for recycling of a varie... more It is of huge importance for sustainability to find a pragmatic solution for recycling of a variety of wastes emitted in small mass such as the case of wallpaper replacements. A combination of two-step sorting scheme and transportation of the wastes in collaboration with the wholesalers was proposed to enhance the efficiency of recycling. The two-step sorting consists of the first sorting at the wallpaper hanging sites to separate and group wastes in a way to avoid heavy additional burden on the hanging job. Secondary sorting is conducted at a Sorting Center to re-group wastes to send to an intermediate processing company for recycling. To minimize the costs for transportation, the grouped wastes emitted at the hanging sites are brought back by the hangers and kept temporally and then moved to the wholesaler(s) on the way to receive new materials. When the wastes at the wholesaler(s) become sufficiently large for economic transportation, a truck is arranged to collect the wastes to transport them to the Sorting Center. A feasibility study to test the practicality of the method confirmed that it could be operable and the cost would be comparable or lower than that currently incurred for disposal of the wastes.
The experimental observations on dioxin formation from various combustion sources, from detailed ... more The experimental observations on dioxin formation from various combustion sources, from detailed incinerator measurements and from laboratory simulation studies including de novo synthesis and precursor formation pathways are discussed in this paper. The de novo synthesis seems to be the dominant mechanism of dioxin formation in actual combustion systems. As de novo synthesis experiments indicate that carbon morphology of certain degenerated graphitic structure is essential for dioxin formation, the morphologies of the particulate emissions from actual combustion sources are examined and it appears that soot particles formed in gas phase combustion reactions consisting of degenerated graphitic structures are the plausible source for de novo synthesis of dioxins. With this understanding dioxin formation in combustion systems is described as a two-stage process: (1) the formation of the graphitic structure of soot particles in the combustion zone; and (2) the conversion of the graphitic structure of soot particles to aromatic compounds including PCDD/Fs in the postcombustion zone. New explanations are given for some seemingly unrelated experimental observations including the high dioxin emissions from municipal waste incineration, the low dioxin emissions from coal combustion, the similar dioxin “fingerprint” from all combustion sources and the discrepancy between the dioxin formation rates observed in laboratory experiments and incinerator measurements.
This paper presents a chemical reaction scheme for de novo synthesis of polychlorinated dibenzo-p... more This paper presents a chemical reaction scheme for de novo synthesis of polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) from carbon in fly ash. The reaction scheme consists of the following mechanistic steps: (1) gaseous O2 chemisorbs upon metallic sites: O2 + 2Cu → 2CuO; (2) the oxygen is transferred to a free site in the carbon structure and the carbon is oxidized to a gaseous product: Cf + CuO → CO + Cu; (3) in the course of carbon gasification, the decomposition of the carbon structure also produces some small aromatic compounds: C (graphitic layer) + aO2 → bCO2 + cCO + dAr. These aromatic compounds include PCBz, PCPh and PCB which then undergo the Ullmann coupling reactions leading to formation. Alternatively, could be formed directly from the decomposition of the carbon structure as a consequence of the in-plane oxygen complexes: C (graphitic layer) + aO2 → bCO2 + cCO + dAr + e ; (4) halogenation/dehalogenation on carbon structure, aromatic compounds and structure may occur concurrently in the above chemical transformations; and (5) decomposition of . Major experimental observations in de novo synthesis can be rationalized using the reaction scheme. Experimental techniques for further investigations are discussed.
ABSTRACT This study identified potential precursors and surrogates of dioxins during thermal extr... more ABSTRACT This study identified potential precursors and surrogates of dioxins during thermal extraction (TE) of a sooty filter dust in a wide range of operating conditions, mainly temperature (120 degrees C-540 degrees C) and time, during direct thermal extraction (DTE) in a dedicated commercial analyzer and indirect thermal extraction (ITE) in a thermobalance used as desorber. Using identical analytical techniques, DTE products were monitored in the range of 120 degrees C-320 degrees C, and ITE products were monitored in the range of 300 degrees C-540 degrees C. Emphasis was on polychlorinated dibenzo-p-dioxins/furans potential precursors and surrogates: aromatic hydrocarbons as well as O, Cl, N, and S compounds. Aliphatic compounds were not monitored. Product distributions differ markedly between both TE techniques: matrix effects eliminate heteroatoms O, Cl, and N, rendering especially DTE less suitable for characterizing a complex sample. Effects of temperature and time were specific for each compound and tentatively explained by low-temperature desorption (up to 240 degrees C) and progressive evolution of volatiles and their eventual decomposition on the matrix at higher temperature. The particular filter dust sample was selected due to its amount of volatiles and fixed carbon; it derived from a baghouse filter, cleaning off-gas from a clean aluminum scrap-melting furnace. TE results strongly diverged from those obtained by solvent-extraction-based analysis. Hence, TE cannot be recommended for analyzing complex samples. A second article compared de novo formation from samples precleaned by TE with raw samples. Such tests may differentiate between dioxin formation and carbonaceous matter (de novo route) from the precursor route involving sorbed organics. Results suggest that there is little or no resemblance between TE and de novo products. The novelty of these articles resides in monitoring numerous dioxin structurally related compounds during (1) TE under reducing conditions and (2) de novo tests in an airflow. The scope of these tests is exploratory and the results suggested strong influence of the matrix on the products evolved.
Titania supported vanadium oxide is a renowned catalyst for the abatement of polychlorinated dibe... more Titania supported vanadium oxide is a renowned catalyst for the abatement of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) from gas effluents. To develop more active formulations, researchers mainly rely on lab-scale experiments on “PCDD/Fs-mimicking substances”, like (chloro)-benzene. Using such model compounds is convenient whereas handling PCDD/Fs in the laboratory is potentially hazardous and complicated. Recent studies, however, challenged some foremost conclusions of model compound based studies, starting from the observation that different model compounds gave contrasted results. Thus the present work aims at confronting some of these dubious conclusions with direct experimental tests on PCDD/Fs. One reference V2O5/TiO2 catalyst and three modified formulations (V2O5/TiO2–SO4, V2O5–MoO3/TiO2, and V2O5–WO3/TiO2) have been evaluated. A dedicated apparatus was used which allows safe and reliable tests on a mixture of PCDD/Fs congeners. Some of the previously proposed catalyst improvement strategies actually prove to be disadvantageous in the removal of PCDD/Fs. In particular, MoO3- and WO3-modified catalysts were significantly less active than the reference catalyst. These observations show that conclusions from model compound based studies must be drawn with care and should ideally be confronted with tests on the actual target pollutants.► V2O5/TiO2 catalysts are recognized catalysts for the abatement of PCDD/Fs. ► Most studies rely on the use of model compounds. ► Contrasted results were obtained with different model. ► Tests on PCDD/Fs are necessary to make relevant recommendations. ► MoO3 and WO3-promoted catalysts are in fact less active.
In thermal metallurgical processes such as iron ore sintering and metal smelting operations, larg... more In thermal metallurgical processes such as iron ore sintering and metal smelting operations, large flows of off-gases are generated. Mainly due to residue recycling in such processes, chlorine and volatile organics are always present in the feed. As a consequence of “de novo” formation, the off-gases from such processes typically contain dioxins in the range 0.3–30 ng I-TEQ/Nm3. So far there are only very few studies about the mechanisms of dioxin formation and destruction in these metallurgical processes. In an European Union (EU) research project “Minimization of dioxins in thermal industrial processes: mechanisms, monitoring and abatement (MINIDIP)”, integrated iron and steel plant has been selected as one of the industrial sectors for further investigation. A large number of particulate samples (feed, belt siftings, electrofilter) were collected from the iron ore sintering installations from various steel plants and analyzed for their organochlorocompound contents. Measurable amounts of PCDD/F, PCBz, PCB were found for all samples. The various parameters influencing their de novo synthesis activity were also evaluated in laboratory experiments, and such activity was found to be moderate for samples from the ore sinter belt, but extremely high for some ESP dusts. Fine dust is active in a wide range of temperatures starting at 200°C and declining above 450°C; the optimal temperature for de novo synthesis was found to be around 350°C; some inhibitors, such as triethanolamine, may reduce de novo activity by 50 %, and lowering the O2 concentration in the gas stream leads to a much lower amount of PCDD/F formation. On the basis of their relative mass, typical operating conditions and specific activity of the different samples, the regions in the sintering plant where de novo synthesis may take place were tentatively established.
A kinetic model is developed for PCDD formation from chlorophenol catalysed by incinerator fly as... more A kinetic model is developed for PCDD formation from chlorophenol catalysed by incinerator fly ash. The key step in the model is a Langmuir–Hinshelwood type elementary step for the coupling of two adsorbed chlorophenol species to PCDD. Kinetic expression is derived which can relate PCDD formation rates with process variables including temperature, precursor concentration, fly ash loading and number of active sites in fly ash. Calculated PCDD formation rates based on this kinetic model are in good agreement with laboratory measurements reported in the literature. When the model is applied to industrial incinerator conditions, at maximum a PCDD yield of 10−3 μg/N m3 is calculated.
In order to determine the baseline contamination by polychlorinated dibenzo-p-dioxins (PCDDs) and... more In order to determine the baseline contamination by polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in different areas in China, prior to the construction of municipal solid waste incinerators (MSWIs), a total of 32 representative soil samples was collected near 16 incinerators and analyzed for their PCDD/F concentrations. The PCDD/F baseline concentrations in the soil samples ranged from 0.32 to 11.4 ng I-TEQ kg−1 (dry matter), with average and median value of 2.73 and 2.24 ng I-TEQ kg−1 (dry matter), respectively, and a span between maximum and minimum recorded value of 36. The PCDD homologues predominated in 26 out of 32 soil samples, with the ratio (PCDDs)/(PCDFs) ranging from 1.1 to 164; however in the other 6 samples, PCDF homologues were larger, with the same ratio varying from 0.04 to 0.8. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were used to examine PCDD/F amount and profile in these soil samples, and their possible associations with known emission sources: in this process 6 really distinct isomer fingerprints were identified. Background PCDD/F levels and profiles were comparable to those found in soils from China and other countries and indicate a rather low baseline PCDD/F contamination of soils. The present data provide the tools for future assessment of a possible impact of these MSWIs.► Baseline soil levels of PCDD/Fs near 16 MSW incinerators were monitored. ► PCDD homologues predominated in most soil samples, indicating a typical background profile. ► Rather low baseline contamination levels were compared with worldwide scope. ► The results of PCA and HCA showed that these soils were exposed to different sources.
Journal of Material Cycles and Waste Management, 2010
For almost 10 years, Vinyl 2010 has provided original approaches to technical, environmental, and... more For almost 10 years, Vinyl 2010 has provided original approaches to technical, environmental, and political problems relating to poly(vinyl chloride) (PVC) material cycles and waste management. On the one hand, PVC has outstanding qualities in a wide range of applications; on the other hand, concerns about potential impacts attributed to production, additives, and waste management led to calls for PVC-specific regulations and mandatory substitution in certain applications. Considering the entire life cycle of PVC products, the industry proposed a comprehensive set of measures rendering production cleaner, eliminating controversial additives, and promoting responsible management of waste, favoring recycling. Vinyl 2010 can now be regarded as a highly successful example of applying voluntary commitments instead of the more usual command and control approach from regulatory authorities.
PCDD/F homologue profiles and 2,3,7,8 chlorine-substituted congener patterns are studied using pr... more PCDD/F homologue profiles and 2,3,7,8 chlorine-substituted congener patterns are studied using principal component analysis and hierarchical cluster analysis. Measurement data from different industrial metallurgical processes such as iron and steel manufacturing, copper smelters and aluminium plants are compared. It appears that the PCDD/F homologue profiles from industrial metallurgical processes are similar to those from municipal solid waste incinerators. The 2,3,7,8 chlorine-substituted congener pattern from copper smelters is also very similar to that of municipal solid waste incinerators. However, the 2,3,7,8 chlorine-substituted congener pattern from an aluminum plant is very different, 2,3,7,8-TCDF being by far the most important TCDF congener.
Material recycling (MR.) is attractive for society because it reduces the use of resources and th... more Material recycling (MR.) is attractive for society because it reduces the use of resources and the amount of waste generated for disposal. Although theoretically the environmental benefits of MR are obvious, currently it is not being applied widely. The reason for the slow development of MR is economic — it simply costs more to recycle than to use virgin raw materials. This situation will continue as long as the costs of environmental impacts are not fully integrated into the cost calculations of all the stakeholders such as producers, converters, users, recyclers, and waste operators. Since the end of the war prices of both raw materials and energy have steadily declined in real terms, albeit with some temporary exceptions caused by political or supply problems. Cheap raw materials, combined with mass production techniques, have made cheap final products possible. The low intrinsic cost of landfilling, which is still a low-eost solid waste management option, makes waste disposal considerably cheaper thanreuse or recycling. This is mainly because selective collection, handling, sorting and intermediate storage of waste for MR is labour-intensive. Furthermore, the quality of goods manufactured from recycled materials is often much lower thanwhen virgin material is used in production. Consequently, they have fewer market outlets compared to goods made with virgin raw materials. The development of MR is also being thwarted by the absence of a scale-effect, limited outlets and low demand, as well as insufficient prospects for research. In practice only those materials (such as gold, lead, iron and steel, and some other metals), whose properties are not degraded by recycling, are now being recycled in large quantities. Large quantities of some of the lower-quality recycled mass products, such as hygienic paper for which there is a strong demand, are also being produced. There is thus a ‘vicious circle’ operating to inhibit the wider development of MR. Thus, a strategic management to promote MR depends on the creation of structurally sound economic conditions. It is argued that MR would attract necessary investment only when the aforementioned ’vicious circle ‘ is replaced by a ‘virtuous circle ‘ characterised by a growing scale-effect that would ensure regular and reliable supply of goods of the right quality and quantity made from recycled materials. It is also argued that a strategic management plan to favour MR should comprise the following: (a) an integrated approach to MR to facilitate the involvement of operators from both virgin and recycling systems: (b) creation of stable conditions for long-term investment in progranunes to promote MR; and (c) inputs and actions from competent authorities to facilitate the creation of the ‘virtuous circle ‘ via demand-side management (in order mainly to create a guaranteed minimum demand and for demonstrating MR).
Waste incineration is becoming increasingly necessary to tackle the rapidly rising amounts of mun... more Waste incineration is becoming increasingly necessary to tackle the rapidly rising amounts of municipal solid waste (MSW); in China many large cities are already surrounded by a girdle of landfills. Still, the not-in-my-backyard (nimby) syndrome holds strong. This attitude stems from fear of dioxins. These have been associated with incineration (‘dioxin factories’) and at times also with polyvinylchloride. In this paper this issue is analysed. China should build additional trust in MSW incineration, following promulgation of stricter emission standards, enforced by stringent controls.
A kinetic model is developed for de novo synthesis of PCDD/F from carbon in incinerator fly ash. ... more A kinetic model is developed for de novo synthesis of PCDD/F from carbon in incinerator fly ash. The main mechanistic steps considered in the model are carbon gasification, PCDD/F formation, desorption and degradation. Rate equations are derived which can relate PCDD/F formation with process variables including carbon concentration of fly ash, partial pressure of oxygen, reaction temperature and time. The kinetic model has been verified using laboratory de novo synthesis data reported in the literature. When the model is applied to industrial incinerator conditions, PCDD/F formation levels of 0.1–0.5 in the gas phase and 0.1–1.2 μg/g in the solid phase are calculated, and both are in good agreement with incinerator measurements.
It is of huge importance for sustainability to find a pragmatic solution for recycling of a varie... more It is of huge importance for sustainability to find a pragmatic solution for recycling of a variety of wastes emitted in small mass such as the case of wallpaper replacements. A combination of two-step sorting scheme and transportation of the wastes in collaboration with the wholesalers was proposed to enhance the efficiency of recycling. The two-step sorting consists of the first sorting at the wallpaper hanging sites to separate and group wastes in a way to avoid heavy additional burden on the hanging job. Secondary sorting is conducted at a Sorting Center to re-group wastes to send to an intermediate processing company for recycling. To minimize the costs for transportation, the grouped wastes emitted at the hanging sites are brought back by the hangers and kept temporally and then moved to the wholesaler(s) on the way to receive new materials. When the wastes at the wholesaler(s) become sufficiently large for economic transportation, a truck is arranged to collect the wastes to transport them to the Sorting Center. A feasibility study to test the practicality of the method confirmed that it could be operable and the cost would be comparable or lower than that currently incurred for disposal of the wastes.
The experimental observations on dioxin formation from various combustion sources, from detailed ... more The experimental observations on dioxin formation from various combustion sources, from detailed incinerator measurements and from laboratory simulation studies including de novo synthesis and precursor formation pathways are discussed in this paper. The de novo synthesis seems to be the dominant mechanism of dioxin formation in actual combustion systems. As de novo synthesis experiments indicate that carbon morphology of certain degenerated graphitic structure is essential for dioxin formation, the morphologies of the particulate emissions from actual combustion sources are examined and it appears that soot particles formed in gas phase combustion reactions consisting of degenerated graphitic structures are the plausible source for de novo synthesis of dioxins. With this understanding dioxin formation in combustion systems is described as a two-stage process: (1) the formation of the graphitic structure of soot particles in the combustion zone; and (2) the conversion of the graphitic structure of soot particles to aromatic compounds including PCDD/Fs in the postcombustion zone. New explanations are given for some seemingly unrelated experimental observations including the high dioxin emissions from municipal waste incineration, the low dioxin emissions from coal combustion, the similar dioxin “fingerprint” from all combustion sources and the discrepancy between the dioxin formation rates observed in laboratory experiments and incinerator measurements.
This paper presents a chemical reaction scheme for de novo synthesis of polychlorinated dibenzo-p... more This paper presents a chemical reaction scheme for de novo synthesis of polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) from carbon in fly ash. The reaction scheme consists of the following mechanistic steps: (1) gaseous O2 chemisorbs upon metallic sites: O2 + 2Cu → 2CuO; (2) the oxygen is transferred to a free site in the carbon structure and the carbon is oxidized to a gaseous product: Cf + CuO → CO + Cu; (3) in the course of carbon gasification, the decomposition of the carbon structure also produces some small aromatic compounds: C (graphitic layer) + aO2 → bCO2 + cCO + dAr. These aromatic compounds include PCBz, PCPh and PCB which then undergo the Ullmann coupling reactions leading to formation. Alternatively, could be formed directly from the decomposition of the carbon structure as a consequence of the in-plane oxygen complexes: C (graphitic layer) + aO2 → bCO2 + cCO + dAr + e ; (4) halogenation/dehalogenation on carbon structure, aromatic compounds and structure may occur concurrently in the above chemical transformations; and (5) decomposition of . Major experimental observations in de novo synthesis can be rationalized using the reaction scheme. Experimental techniques for further investigations are discussed.
ABSTRACT This study identified potential precursors and surrogates of dioxins during thermal extr... more ABSTRACT This study identified potential precursors and surrogates of dioxins during thermal extraction (TE) of a sooty filter dust in a wide range of operating conditions, mainly temperature (120 degrees C-540 degrees C) and time, during direct thermal extraction (DTE) in a dedicated commercial analyzer and indirect thermal extraction (ITE) in a thermobalance used as desorber. Using identical analytical techniques, DTE products were monitored in the range of 120 degrees C-320 degrees C, and ITE products were monitored in the range of 300 degrees C-540 degrees C. Emphasis was on polychlorinated dibenzo-p-dioxins/furans potential precursors and surrogates: aromatic hydrocarbons as well as O, Cl, N, and S compounds. Aliphatic compounds were not monitored. Product distributions differ markedly between both TE techniques: matrix effects eliminate heteroatoms O, Cl, and N, rendering especially DTE less suitable for characterizing a complex sample. Effects of temperature and time were specific for each compound and tentatively explained by low-temperature desorption (up to 240 degrees C) and progressive evolution of volatiles and their eventual decomposition on the matrix at higher temperature. The particular filter dust sample was selected due to its amount of volatiles and fixed carbon; it derived from a baghouse filter, cleaning off-gas from a clean aluminum scrap-melting furnace. TE results strongly diverged from those obtained by solvent-extraction-based analysis. Hence, TE cannot be recommended for analyzing complex samples. A second article compared de novo formation from samples precleaned by TE with raw samples. Such tests may differentiate between dioxin formation and carbonaceous matter (de novo route) from the precursor route involving sorbed organics. Results suggest that there is little or no resemblance between TE and de novo products. The novelty of these articles resides in monitoring numerous dioxin structurally related compounds during (1) TE under reducing conditions and (2) de novo tests in an airflow. The scope of these tests is exploratory and the results suggested strong influence of the matrix on the products evolved.
Titania supported vanadium oxide is a renowned catalyst for the abatement of polychlorinated dibe... more Titania supported vanadium oxide is a renowned catalyst for the abatement of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) from gas effluents. To develop more active formulations, researchers mainly rely on lab-scale experiments on “PCDD/Fs-mimicking substances”, like (chloro)-benzene. Using such model compounds is convenient whereas handling PCDD/Fs in the laboratory is potentially hazardous and complicated. Recent studies, however, challenged some foremost conclusions of model compound based studies, starting from the observation that different model compounds gave contrasted results. Thus the present work aims at confronting some of these dubious conclusions with direct experimental tests on PCDD/Fs. One reference V2O5/TiO2 catalyst and three modified formulations (V2O5/TiO2–SO4, V2O5–MoO3/TiO2, and V2O5–WO3/TiO2) have been evaluated. A dedicated apparatus was used which allows safe and reliable tests on a mixture of PCDD/Fs congeners. Some of the previously proposed catalyst improvement strategies actually prove to be disadvantageous in the removal of PCDD/Fs. In particular, MoO3- and WO3-modified catalysts were significantly less active than the reference catalyst. These observations show that conclusions from model compound based studies must be drawn with care and should ideally be confronted with tests on the actual target pollutants.► V2O5/TiO2 catalysts are recognized catalysts for the abatement of PCDD/Fs. ► Most studies rely on the use of model compounds. ► Contrasted results were obtained with different model. ► Tests on PCDD/Fs are necessary to make relevant recommendations. ► MoO3 and WO3-promoted catalysts are in fact less active.
In thermal metallurgical processes such as iron ore sintering and metal smelting operations, larg... more In thermal metallurgical processes such as iron ore sintering and metal smelting operations, large flows of off-gases are generated. Mainly due to residue recycling in such processes, chlorine and volatile organics are always present in the feed. As a consequence of “de novo” formation, the off-gases from such processes typically contain dioxins in the range 0.3–30 ng I-TEQ/Nm3. So far there are only very few studies about the mechanisms of dioxin formation and destruction in these metallurgical processes. In an European Union (EU) research project “Minimization of dioxins in thermal industrial processes: mechanisms, monitoring and abatement (MINIDIP)”, integrated iron and steel plant has been selected as one of the industrial sectors for further investigation. A large number of particulate samples (feed, belt siftings, electrofilter) were collected from the iron ore sintering installations from various steel plants and analyzed for their organochlorocompound contents. Measurable amounts of PCDD/F, PCBz, PCB were found for all samples. The various parameters influencing their de novo synthesis activity were also evaluated in laboratory experiments, and such activity was found to be moderate for samples from the ore sinter belt, but extremely high for some ESP dusts. Fine dust is active in a wide range of temperatures starting at 200°C and declining above 450°C; the optimal temperature for de novo synthesis was found to be around 350°C; some inhibitors, such as triethanolamine, may reduce de novo activity by 50 %, and lowering the O2 concentration in the gas stream leads to a much lower amount of PCDD/F formation. On the basis of their relative mass, typical operating conditions and specific activity of the different samples, the regions in the sintering plant where de novo synthesis may take place were tentatively established.
A kinetic model is developed for PCDD formation from chlorophenol catalysed by incinerator fly as... more A kinetic model is developed for PCDD formation from chlorophenol catalysed by incinerator fly ash. The key step in the model is a Langmuir–Hinshelwood type elementary step for the coupling of two adsorbed chlorophenol species to PCDD. Kinetic expression is derived which can relate PCDD formation rates with process variables including temperature, precursor concentration, fly ash loading and number of active sites in fly ash. Calculated PCDD formation rates based on this kinetic model are in good agreement with laboratory measurements reported in the literature. When the model is applied to industrial incinerator conditions, at maximum a PCDD yield of 10−3 μg/N m3 is calculated.
In order to determine the baseline contamination by polychlorinated dibenzo-p-dioxins (PCDDs) and... more In order to determine the baseline contamination by polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in different areas in China, prior to the construction of municipal solid waste incinerators (MSWIs), a total of 32 representative soil samples was collected near 16 incinerators and analyzed for their PCDD/F concentrations. The PCDD/F baseline concentrations in the soil samples ranged from 0.32 to 11.4 ng I-TEQ kg−1 (dry matter), with average and median value of 2.73 and 2.24 ng I-TEQ kg−1 (dry matter), respectively, and a span between maximum and minimum recorded value of 36. The PCDD homologues predominated in 26 out of 32 soil samples, with the ratio (PCDDs)/(PCDFs) ranging from 1.1 to 164; however in the other 6 samples, PCDF homologues were larger, with the same ratio varying from 0.04 to 0.8. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were used to examine PCDD/F amount and profile in these soil samples, and their possible associations with known emission sources: in this process 6 really distinct isomer fingerprints were identified. Background PCDD/F levels and profiles were comparable to those found in soils from China and other countries and indicate a rather low baseline PCDD/F contamination of soils. The present data provide the tools for future assessment of a possible impact of these MSWIs.► Baseline soil levels of PCDD/Fs near 16 MSW incinerators were monitored. ► PCDD homologues predominated in most soil samples, indicating a typical background profile. ► Rather low baseline contamination levels were compared with worldwide scope. ► The results of PCA and HCA showed that these soils were exposed to different sources.
Journal of Material Cycles and Waste Management, 2010
For almost 10 years, Vinyl 2010 has provided original approaches to technical, environmental, and... more For almost 10 years, Vinyl 2010 has provided original approaches to technical, environmental, and political problems relating to poly(vinyl chloride) (PVC) material cycles and waste management. On the one hand, PVC has outstanding qualities in a wide range of applications; on the other hand, concerns about potential impacts attributed to production, additives, and waste management led to calls for PVC-specific regulations and mandatory substitution in certain applications. Considering the entire life cycle of PVC products, the industry proposed a comprehensive set of measures rendering production cleaner, eliminating controversial additives, and promoting responsible management of waste, favoring recycling. Vinyl 2010 can now be regarded as a highly successful example of applying voluntary commitments instead of the more usual command and control approach from regulatory authorities.
PCDD/F homologue profiles and 2,3,7,8 chlorine-substituted congener patterns are studied using pr... more PCDD/F homologue profiles and 2,3,7,8 chlorine-substituted congener patterns are studied using principal component analysis and hierarchical cluster analysis. Measurement data from different industrial metallurgical processes such as iron and steel manufacturing, copper smelters and aluminium plants are compared. It appears that the PCDD/F homologue profiles from industrial metallurgical processes are similar to those from municipal solid waste incinerators. The 2,3,7,8 chlorine-substituted congener pattern from copper smelters is also very similar to that of municipal solid waste incinerators. However, the 2,3,7,8 chlorine-substituted congener pattern from an aluminum plant is very different, 2,3,7,8-TCDF being by far the most important TCDF congener.
Material recycling (MR.) is attractive for society because it reduces the use of resources and th... more Material recycling (MR.) is attractive for society because it reduces the use of resources and the amount of waste generated for disposal. Although theoretically the environmental benefits of MR are obvious, currently it is not being applied widely. The reason for the slow development of MR is economic — it simply costs more to recycle than to use virgin raw materials. This situation will continue as long as the costs of environmental impacts are not fully integrated into the cost calculations of all the stakeholders such as producers, converters, users, recyclers, and waste operators. Since the end of the war prices of both raw materials and energy have steadily declined in real terms, albeit with some temporary exceptions caused by political or supply problems. Cheap raw materials, combined with mass production techniques, have made cheap final products possible. The low intrinsic cost of landfilling, which is still a low-eost solid waste management option, makes waste disposal considerably cheaper thanreuse or recycling. This is mainly because selective collection, handling, sorting and intermediate storage of waste for MR is labour-intensive. Furthermore, the quality of goods manufactured from recycled materials is often much lower thanwhen virgin material is used in production. Consequently, they have fewer market outlets compared to goods made with virgin raw materials. The development of MR is also being thwarted by the absence of a scale-effect, limited outlets and low demand, as well as insufficient prospects for research. In practice only those materials (such as gold, lead, iron and steel, and some other metals), whose properties are not degraded by recycling, are now being recycled in large quantities. Large quantities of some of the lower-quality recycled mass products, such as hygienic paper for which there is a strong demand, are also being produced. There is thus a ‘vicious circle’ operating to inhibit the wider development of MR. Thus, a strategic management to promote MR depends on the creation of structurally sound economic conditions. It is argued that MR would attract necessary investment only when the aforementioned ’vicious circle ‘ is replaced by a ‘virtuous circle ‘ characterised by a growing scale-effect that would ensure regular and reliable supply of goods of the right quality and quantity made from recycled materials. It is also argued that a strategic management plan to favour MR should comprise the following: (a) an integrated approach to MR to facilitate the involvement of operators from both virgin and recycling systems: (b) creation of stable conditions for long-term investment in progranunes to promote MR; and (c) inputs and actions from competent authorities to facilitate the creation of the ‘virtuous circle ‘ via demand-side management (in order mainly to create a guaranteed minimum demand and for demonstrating MR).
Waste incineration is becoming increasingly necessary to tackle the rapidly rising amounts of mun... more Waste incineration is becoming increasingly necessary to tackle the rapidly rising amounts of municipal solid waste (MSW); in China many large cities are already surrounded by a girdle of landfills. Still, the not-in-my-backyard (nimby) syndrome holds strong. This attitude stems from fear of dioxins. These have been associated with incineration (‘dioxin factories’) and at times also with polyvinylchloride. In this paper this issue is analysed. China should build additional trust in MSW incineration, following promulgation of stricter emission standards, enforced by stringent controls.
A kinetic model is developed for de novo synthesis of PCDD/F from carbon in incinerator fly ash. ... more A kinetic model is developed for de novo synthesis of PCDD/F from carbon in incinerator fly ash. The main mechanistic steps considered in the model are carbon gasification, PCDD/F formation, desorption and degradation. Rate equations are derived which can relate PCDD/F formation with process variables including carbon concentration of fly ash, partial pressure of oxygen, reaction temperature and time. The kinetic model has been verified using laboratory de novo synthesis data reported in the literature. When the model is applied to industrial incinerator conditions, PCDD/F formation levels of 0.1–0.5 in the gas phase and 0.1–1.2 μg/g in the solid phase are calculated, and both are in good agreement with incinerator measurements.
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