Give me a break, and help yourself! Thanks!

Dioxins were first discovered in the stack gas of municipal solid waste incinerators in 1977. Thereafter, a considerable amount of research has been carried out to elucidate dioxin related issues with various approaches. Management of municipa waste by incineration is a worldwide consensus. The Taiwan Government has issued a policy of constructing more incinerators for municipal waste treatment in 1990. An estimation of twenty one large-scale municipal solid waste incinerators will be completed before 2005. However, conflicts between government and public arose from this policy due to public fear and awareness of adverse health effects caused by pollutants emitted from incineration process. Government has, therefore, promulgated stringent emission regulations, implemented the development and validation of national standard methods for sampling and analysis of dioxins, and funding dioxin related research and monitoring projects.
The thesis focuses on dioxins in the municipal solid waste incinerators, to elucidate the formation behavior of dioxins and dishcarge from different matrices, to understand the relationship between formation and combustion conditions and to reduce dioxins production, emissions and preventing environmental impact.

Dioxins, heavy metals and relevant information were collected and formulated to establish the basic database of Peitou municipal solid waste incinerator. The formation of dioxins and heavy metals in the incineration process was considered a continuous, dynamic and complex process. A macroscopic view from feeding control, incineration control and pollution control revealed an apparent effect on operational conditions. The estimated annual dioxin production of the incineration facility from stack, fly ash and slag are 0.243, 9.24 and 0.48 g, respectively. Contribute to 6.5% of annual dioxin production of 3.7g when 21 municipal solid waste incinerators are all put into operation. The emission factor is estimated as 468 ng-TEQ/ton, about 20% lower than average emission factor 570 ng-TEQ/ton estimated by Taiwan EPA. The annual emission of Cr, Cu, As, Cd, Hg and Pb from stack are 4.06, 8.11, 0.81, 3.65, 24.33 and 56.77 kg; from fly ash are 2235, 9064, 361, 2570, 264, 33880 kg and from slag are 48787, 280922, 2376, 2218, 175 and 167904 kg, respectively. The results showed that the average dioxin content of the five samples in first sampling period exceeded the 0.1 ng-TEQ/m3 regulatory permission level. Other three periods had an average of 0.066 ng-TEQ/m3, which is nearly the same emission level as the trial burn when the incinerator was first set up. For good operating practice, MSWI should be more cautious about combustion conditions, such as temperature in the process, thermal capacity, and APCD operating conditions during start-up and shutdown cycles. Under normal operational conditions, the dioxin removal efficiency fits the designed specifications. In addition, AC injection promotes the reduction of Hg and dioxin content in stack emission. Fabric filter is the major pollution control device for elimination of dioxin and heavy metals emission.

The research analyzes dioxin content in slag and fly ash from Mucha municipal solid waste incinerator after the completion of dioxin abatement work. The results are used to establish the database of dioxin content in slag and fly ash, to understand the effects of incineration and operation conditions on dioxin formation, to investigate the dioxin’s distribution and formation behavior, and to reveal dioxin’s relationship with operating parameters. The results indicate the selective catalytic reactor’s (SCR’s) dioxin removal efficiency is 93% and 98%, respectively. The average dioxins content in the fly ash were 4689, 9698 and 15330 pg-TEQ/g dm, respectively, at Aug 6th~7th, Sep 4th, and Sep 5th. The dioxins content in the fly ash from electrostatic precipitator (ESP) correlates well with the temperature, which related well to the de novo synthesis. The annual dioxin amount in the fly ash is ca. 8.02 g-TEQ/year. Although ESP efficiently removes most PM, however the formation occurred within the EPS could result in a net increase of PCDD/Fs emission. Operating at the lowest practical temperature is critical in minimizing dioxin emission, and it may be necessary to scrub the acid gas from the post-combustion flue gas to permit lowering ESP operating temperature to certain level where corrosion is not a problem. After retrofitting, the findings verified the capability of newly installed SCR to successfully comply with minimum cost of space and requirements demanded and the dioxin emission below regulatory permitted level.

The above two typical municipal solid waste incinerators in Taiwan were compared based on the aforementioned analytical results; Facility A (Mucha) consisted of an ESP, a wet scrubber (WS) and a SCR; while facility B (Peitou) employed lime plus activated carbon (AC) injection in a semi-dry scrubber (SDS) and a baghouse fabric filter (FF). The ESP operating temperature is the most important factor affecting PCDD/Fs formation in the gas cleaning system. FF is more effective than ESP in controlling PCDD/Fs because of higher particulate matter (PM) control efficiency. Good combustion practice coupled with air pollution control device (APCD) operating temperature maintained in the region of 200 oC or below, will permit consistent achievement of PCDD/F emissions < 0.1 ng TEQ/m3. The dioxin concentrations in the slag from both MSWIs are similar. The dioxin concentration in fly ash in facility A is 3.1 and 2.9 times to that in facility B during normal operation and start-up period. It can be ascribed to different characteristics of the APCD and operating parameters used in the facility. FF is more effective than ESP in controlling PCDD/Fs because of higher PM control efficiency. Any PM not collected may contain PCDD/Fs. PM control devices collection efficiencies > 99% are probably necessary to control adequately PCDD/Fs emissions.

1. ROC EPA (1997), Regulatory and emission standard for dioxins from municipal waste incinerators.
2. S. Marklund, I. Fangmark, C. Rappe, Formation and degradation of chlorinated aromatic compounds in an air pollution control device for MSW combustor, Chemosphere, 25, 139-142, 1992.
3. W.M. Sierhuis, C. de Vries, J.G.P. Born, PCDD/F emissions related to the opration conditions of the flue gas clean system of the MWI Amsterdam, Chemosphere, 32, 159-168, 1996.
4. M. Giugliano, S. Cernuschi, M. Grosso, E. Aloigi, R. Miglio, PCDD/F mass balance in the flue gas clean units of a MSW incinerator plant, Chemosphere, 46, 1321-1328, 2002.
5. K. Everaert, J. Baeyens, J. Degreve, Removal of PCDD/F from incinerator flue gases by entrained-phase adsorption, J. Air & Waste Manage. Assoc., 51, 718-724, 2002.
6. E. Abad, J. Caixach, J. Rivera, Improvements in dioxin abatement strategies at a municipal waste management plant in Barcelona, Chemosphere, 50, 1175-1182, 2003.
7. E.S. Olson, S.J. Miller, R.K. Sharma, G.E. Dunham, S.A. Benson, Catalytic effects of carbon sorbents for mercury capture, Journal of Hazardous Materials, 74, 61-79, 2000.
8. J.D. Kilgroe, Control of dioxin, furan and mercury emissions from MSWI, Journal of Hazardous Materials, 47, 163-194, 1996.
9. Pei-Tou refuse incineration plant, http://www.ptrip.gov.tw/
10. ROC EPA (1998), Sampling method for dioxins and furans from stack emission, NIEA A807.70C.
11. Bert van Bavel, 5th Round Fly Ash, 1999; 6th Round Fly Ash, 2000; 7th Round Soil/Sewage Sludge, Fly Ash, 2001; 8th Round Incineration, Soil/Sediment, 2002.
12. The Investigation of the relationship between the emission and transport of dioxins and heavy metals with feed-in materials at the post-combustion region, Contract No. PT89-102, December. 2000. Bureau of Environmental Protection, Taipei Municipal Government.
13. N. Kazuo, K. Sayuri, T. Hiroshi, The origin and behavior of lead, cadmium and antimony in MSW incinerator, Waste Management, 16, 5-6, 509-517, 1996.
14. G. Mckay, Dioxin characterization, formation, and minimization during MSWI: Review, Chemical Engineering 86, 343-368, 2002.
15. O. Lindqvist, P. Schager, Continuous measurements of mercury in flue gases from waste incinerators and combustion plants, VDI Berichte (NR. 838), 401, 1990.
16. E.S. Olson, Catalytic effects of carbon sorbents for Hg capture, Journal of Hazardous Materials, 74, 61-79, 2000.
1. Taiwan Waste Incinerator Dioxin Control and Emission Standard August 1997.
2. R. Boos, R. Budin, M. Hartl, M. Stock, F. Wurst, PCDD- and PCDF- destruction by a SCR-unit in a municipal waste incinerator, Chemosphere, 25, 375-382, 1992.
3. Y. Ide, K. Kashiwabara, S. Okada, T. Mori, M. Hara, Catalytic decomposition of dioxin from MSW incinerator flue gas, Chemosphere, 32, 189-198, 1996.
4. R. Weber, T. Sakurai, H. Hagenmaier, Low temperature decomposition of PCDD/PCDF, chlorobenzenes and PAHs by TiO2-based V2O5-WO3 catalyst, Appl. Catal., B20, 249-256, 1999.
5. P. Liljelind, J. Unsworth, O. Maaskant, S. Marklund, Removal of dioxin and related aromatic hydrocarbons from flue gas stream by adsorption and catalytic destruction, Chemosphere, 42, 615-623, 2001.
6. Mu-Cha refuse incineration plant, http://www.mcrip.taipei.gov.tw/.
7. Sampling method for dioxins and furans from stack emission, NIEA A808.70B., ROC EPA 1998.
8. Test method 0023A, In SW846, Office of Solid Waste and Emergency Response; Office of Solid Waste, USEPA: Washington, DC, 1996.
9. US EPA 1613B ”Tetra- through Octa-Chlorinated Dioxins and Furans by Isotope Dilution HRGC/HRMS”, 1999.
10. Analytical method for dioxins and furans from stack emission, NIEA A808.70B., ROC EPA 1998.
11. The Establishment and Research of dioxin in fly ash and bottom ash in Mu-Cha refuse incineration plant, Contract No. 90-29, December. 2001. Bureau of Environmental Protection, Taipei Municipal Government.
12. K. Yasuda, M. Takahashi, The emission of polycyclic aromatic hydrocarbons from municipal solid waste incinerators during the combustion cycle, Journal of the Air & Waste Management Association, 48 (5), 441-447, 1998.
13. National Research Council, Waste Incineration and Public Health: Report on the Committee on Health Effect of Waste Incineration. National Academy Press: Washington, DC, 1999.
14. E. Abad, J. Caixach, J. Rivera, Improvements in dioxin abatement strategies at a municipal waste management plant in Barcelona, Chemosphere, 50 (9), 1175- 1182, 2003.
15. J.D. Kilgroe, Control of dioxin, furan and mercury emissions from MSWI, Journal of Hazardous Materials, 47, 163-194, 1996.
16. L. Stieglitz, H. Vogg, On formation conditions of PCDD/PCDF in fly ash from municipal waste incinerators, Chemosphere, 16, 1917-1922, 1987.
17. R. Luijk, D.M. Akkerman, P. Slot, K. Olei, F. Kapteijn, Mechanism of formation of polychlorinated dibenzo-p-dioxins and dibenzofurans in the catalyzed combustion of carbon, Environ. Sci. Technol., 28, 312-321, 1994.
18. M. Milligan, E. Altwicker, Mechanistic aspects of the de novo synthesis of polychlorinated dibenzo-p-dioxins and furans in fly-ash from experiments using isotopically labeled reagents, Environ. Sci. Technol., 29, 1353-1358, 1995.
19. L. Stieglitz, H. Bautz, W. Roth, Investigation of precursor reactions in the de novo-synthesis of PCDD/PCDF on fly ash, Chemosphere, 34, 1083-1090, 1997.
20. G. Mckay, Dioxin characterization, formation, and minimization during MSWI: Review, Chemical Engineering 86, 343-368, 2002.
21. E. Wikström, S. Ryan, A. Touati, B.K. Gullet, Key parameters for de novo formation of polychlorinated dibenzo-p-dioxins and dibenzofurans, Environ. Sci. Technol., 37, 1962-1970, 2003.
1. G. Mckay, Dioxin characterization, formation, and minimization during MSWI: Review, Chemical Engineering, 86, 343-368, 2002.
2. Mu-Cha refuse incineration plant, http://www.mcrip.taipei.gov.tw/
3. Pei-Tou refuse incineration plant, http://www.ptrip.gov.tw/
4. ROC EPA (1998), Sampling method for dioxins and furans from stack emission, NIEA A807.70C.
5. US EPA 1613B ”Tetra- through Octa-Chlorinated Dioxins and Furans by Isotope Dilution HRGC/HRMS”, 1999.
6. The Establishment and Research of dioxin in fly ash and bottom ash in Mu-Cha refuse incineration plant, Contract No. 90-29, December. 2001. Bureau of Environmental Protection, Taipei Municipal Government.
7. The Investigation of the relationship between the emission and transport of dioxins and heavy metals with feed-in materials at the post-combustion region, Contract No. PT89-102, December. 2000. Bureau of Environmental Protection, Taipei Municipal Government.
8. J.D. Kilgroe, Control of dioxin, furan and mercury emissions from MSWI, Journal of Hazardous Materials, 47, 163-194, 1996.