Emissions of Dioxins in Municipal Solid Waste Incineration Professor Stellan Marklund Umeå University Sweden
Why this concern of Dioxins. 2,3,7,8-TCDD One of the most toxic compounds in the world Carcinogenic Persistent fat soluble pollutant Formation in combustion systems 2010-02-04 Szczecin 2
Dioxins in Combustion Processes MSW combustion Biofuel combustion Co-combustion Back yard burning Accidental fires Household fires Dumpsite fires Forest fires 2010-02-04 Szczecin 3
Dioxins Indicator of the performances of the plant A measure of the toxicity in the emissions Can be used as a marker of other organic pollutants Easy to sample and detect in low concentrations (ppt) 2010-02-04 Szczecin 4
What is Dioxins Polychlorinated dibenzo-p-dioxins (PCDDs) Polychlorinated bibenzofurans Polychlorinated biphenyls I-Teq = PCDDs + PCDFs WHO-Teq = PCDDs + PCDFs + PCBs (PCDFs) (PCBs) Other compounds can be included in the future 2010-02-04 Szczecin 5
TCDD-equivalents The total dioxin toxicity in the sample Concentration of a specific isomer multiplied with its TE-factor Add together all 17 isomers TE-value I-TEq = International TCDD equivalents WHO-TEq = I-TEq + Toxic } PCBs Eadon equivalents Nordic TCDD equivalents Different TE-factors WHO equivalents 2010-02-04 Szczecin 6
Where can dioxins be found? g/year in Sweden to the air 100 90 80 70 60 50 40 30 20 1987 1989 1997 2007 10 0 Secondary iron/steel production Secondary non-ferrus smelters Foundries Cement industry Paper and Pulp mills (air) Paper and Pulp mills (water) MSW combustion < 1g/year 2010-02-04 Szczecin 7
Dioxin flux Dioxins are present in the waste that goes to combustion. Decompose in the combustion zone. New formation in the cooling zone. Removes in the APC device. Mass balance in modern plants. Decomposition > Formation rate Mush less in emission to air than in untreated waste. 2010-02-04 Szczecin 8
Formation of dioxins Dioxins form in the cooling zone. Formation pathway need chlorine and a catalyst. Catalyst can be cupper or other metal or even bromine. Concentration of catalyst is rate determining. Chlorine origin and concentration unimportant. 2010-02-04 Szczecin 9
Municipal Solid Waste Combustion Dioxins in flue gas. Small compare with other sources. Dioxins in bottom ash (slagg). Low levels of dioxins in bottom ashes. Dioxins in APCD-residues. Most dioxins end up in the APCD-residues. Hard bonded to the ash do not leach. Slow decomposition rate in the ash. 2010-02-04 Szczecin 10
Air emissions of dioxins Air emissions of dioxins from MSW combustion is a minor source in Sweden Air emissions of dioxins from landfill fires are higher Biofuel combustion emit more dioxins to the air than MSW combustion 2010-02-04 Szczecin 11
Combusted MSW insweden 4 500 000 4 000 000 3 500 000 Mängd hushållsavfall till förbränning, ton Mängd övrigt avfall till förbränning, ton Total mängd till förbränning, ton 3 000 000 2 500 000 2 000 000 1 500 000 1 000 000 500 000 0 1999 2000 2001 2002 2003 2004 2005 2006 2010-02-04 Szczecin 12
Avesta Boden Bollnäs Borlänge Borås Eksjö Finspång Göteborg Halmstad Hässleholm Jönköping Karlskoga Karlstad Kiruna Kumla Köping Lidköping Linköping Ljungby Malmö Mora Norrköping Skövde Stockholm Sundsvall Södertälje Umeå Uppsala Västervik MSW-plants insweden 700 000 600 000 Total mängd avfall 2006, ton Varav hushållsavfall 2006, ton 500 000 400 000 300 000 200 000 100 000 0 2010-02-04 Szczecin 13
Avesta Bollnäs Borlänge Borås Finspång Göteborg Halmstad ( ) Hässleholm Jönköping Karlskoga Karlstad Kiruna Köping Lidköping Linköping Ljungby Malmö ( ) Norrköping Stockholm ( ) Sundsvall Södertälje Umeå Uppsala Västervik Dioxins in APCD-residues ng/g APCD-residue (2006) 20,00 18,00 16,00 Dioxinhalt i rökgasreningsrester 1999, ng/g (I-TEQ) Dioxinhalt i rökgasreningsrester 2006, ng/g (WHO-TEQ) 14,00 12,00 10,00 8,00 6,00 4,00 2,00 0,00 2010-02-04 Szczecin 14
Ash stability Dioxins have a very low solubility in water. Dioxins are adsorbed strong to activated carbons The leachate from fly ash contain lower levels of dioxins than rainwater Stabilization of fly ash can change the adsorbtion properties 2010-02-04 Szczecin 15
Conclutions The reduction of dioxins in air emissions from MSW combustion has been considerable the last two decade The reduction of dioxins in fly ash has been small during the same period The fly ash adsorb dioxins strongly to it s activated carbon and will not emit them to the environment The decomposition time of dioxins on fly ash is very long (several decades) 2010-02-04 Szczecin 16
MSW combustion Combustion enriches the dioxins in the small APCD-residue fraction. ACPD-residue fraction can be detoxified or stored on a safe landfill. In a modern plant, the amount of dioxin is equal or lower in the rest products than in the waste. Combustion can remove dioxins and other pollutants from the eco-circle. 2010-02-04 Szczecin 17
Thank you for your attention! 2010-02-04 Szczecin 18
Dioxins in Swedish fly ash MSW combustion Dioxins in air emission Dioxins in collected filter ash Dioxins in bottom ash 120 100 80 60 40 20 0 2010-02-04 Szczecin Flue gas Bottom ash Filter ash 19
Reduction in MSW combustion g/year 200 10x kton 150 100 50 0 1980 1990 2000 Air emission Fly ash MSW 2010-02-04 Szczecin 20
Dioxins in the environment 350 300 250 200 150 100 50 0 OCDD HpCDD HxCDD OCDF HpCDF HxCDF Rainwater Leachate 2010-02-04 Szczecin 21