Emissions of Dioxins in Municipal Solid Waste Incineration. Professor Stellan Marklund Umeå University Sweden

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1 Emissions of Dioxins in Municipal Solid Waste Incineration Professor Stellan Marklund Umeå University Sweden

2 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 Szczecin 2

3 Dioxins in Combustion Processes MSW combustion Biofuel combustion Co-combustion Back yard burning Accidental fires Household fires Dumpsite fires Forest fires Szczecin 3

4 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) Szczecin 4

5 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 Szczecin 5

6 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 Szczecin 6

7 Where can dioxins be found? g/year in Sweden to the air 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 Szczecin 7

8 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 Szczecin 8

9 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 Szczecin 9

10 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 Szczecin 10

11 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 Szczecin 11

12 Combusted MSW insweden Mängd hushållsavfall till förbränning, ton Mängd övrigt avfall till förbränning, ton Total mängd till förbränning, ton Szczecin 12

13 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 Total mängd avfall 2006, ton Varav hushållsavfall 2006, ton Szczecin 13

14 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, Szczecin 14

15 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 Szczecin 15

16 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) Szczecin 16

17 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 Szczecin 17

18 Thank you for your attention! Szczecin 18

19 Dioxins in Swedish fly ash MSW combustion Dioxins in air emission Dioxins in collected filter ash Dioxins in bottom ash Szczecin Flue gas Bottom ash Filter ash 19

20 Reduction in MSW combustion g/year x kton Air emission Fly ash MSW Szczecin 20

21 Dioxins in the environment OCDD HpCDD HxCDD OCDF HpCDF HxCDF Rainwater Leachate Szczecin 21