Chemosphere, Vol. 15, Nos. 9-12, pp 2045-2048, 1986

Specific precursors in the fuel are a possible cause for the presence of polychlorinated dibenzodioxins (PCDD) and dibenzofurans (PCDF) in waste incinerator emissions. However, if precursors play a key role remains a controversial issue¹. We have earlier^2,3 reported results indicating the importance of the total chlorine input for the production of chloroaromatics. Here we present results from our tests with PCB-incineration at the SAKAB hazardous waste incinerator in Norrtorp, Sweden. We also report other test data from this plant.

Flue gas samples were collected using an all-glass sampling train⁴. Chlorinated benzenes, PCDD and PCDF were quantified relative to standard mixtures. The chemical analyses of PCDD and PCDF were performed either by us, or at the University of Umeå, Sweden. The extraction and clean-up techniques for PCDD and employed by us^5,6 are essentially those developed by Buser⁷. The extracts are analyzed by HRGC/MS⁸.

PCB-combustion

Combustion tests have been made with PCB both as a fluid (Arochlor 1242) and as a contaminant of solid waste (Arochlor 1016 in capacitors). Results are presented in Table 1.

Table 1
Production of PCDD and PCDF during PCB-combustion tests.

PCB input	kg/h	35	90	90
Waste		Fluid	Solid	Solid
Sum tetra-CDF	ng/Nm3*	8.4	7.9	1.7
Sum penta-CDF	ng/Nm3*	17	120	26
Sum tetra-CDD	ng/Nm3*	0.78	2.2	1.4
Sum penta-CDD	ng/Nm3*	38	6.6	2.9

* Concentration upstream of the flue gas cleaning system

For comparison, we present results concerning the average concentrations of PCDD and PCDF in 11 flue gas samples from the SAKAB plant without PCB-combustion (PCB below 25 ppm in the fuel), Table 2.

Table 2
Production of PCDD and PCDF without PCB-combustion, 11 samples.

Waste		Mean	Std dev
Sum tetra-CDF	ng/Nm3*	24	35
Sum penta-CDF	ng/Nm3*	48	29
Sum tetra-CDD	ng/Nm3*	1.9	1.8
Sum penta-CDD	ng/Nm3*	18	25

* Concentration upstream of the flue gas cleaning system

The results do not represent emissions from the plant because a significant separation occurs in the flue gas cleaning system. The flue gas samples were taken directly after the boiler, in order to prevent masking effects from recirculating material in the scrubber system.

PCB-combustion tests were carried out under good combustion conditions. The combustion efficiency calculated using,

CE = (1 - CO/CO2) * 100 %

and was above 99.95 %.

A general conclusion from the tests is that the incineration of considerable amounts of PCB does not effect the production of PCDD and PCDF in this combustion plant.

The same conclusion can be made from our study of the Danish hazardous waste combustion plant, Kommunekemi⁹. In this case the PCB input was 10 kg/h (Arochlor 1254).

Formation

Further analysis of combustion test data from the Norrtorp plant, reported elsewhere², has revealed a close correlation between chloroaromatics and the load of particles >2 µm in the flue gas. The correlation between hexachlorobenzene and particles >2 µm is illustrated in Figure 1.

Figure 1
Hexachlorobenzene (µg/Nm3) as a function of ln particles >2 µm (g/Nm3). Concentrations expressed as dry gas at 10 % CO2.

A possible interpretation of this correlation is that hexachlorobenzene survives the high temperatures of the after-burner when associated with "large" particles. Further studies in this direction may be helpful to elucidate the formation mechanisms for PCDD and PCDF.

We should like to thank our own staff and the other laboratories participating for skilled technical assistance. We also should like to thank the staff at SAKAB for skilled technical assistance and enjoyable cooperation.

1. Hutzinger, 0, Blumich, M J
   Chemosphere 14, 581-600 (1985).
2. Öberg T, Aittola, J-P, Bergström, J G T Chemosphere 14, 215 - 221, (1985).
3. Öberg, T, Bergström, J G T
   Chemosphere 14, 1081 - 1086, (1985).
4. Bergström, J G T, Eklund, G, Warman, K
   Presented at the Sixth International Symposium on Polynuclear Aromatic Hydrocarbons, 27 29 October 1981 in Columbus, Ohio, USA.
5. Eklund, G, Strömberg, B
   Report E2-81/9, Studsvik Energiteknik AB, 1981.
6. Hydén, E
   Report MKS-84/57. Environmental Consultants at Studsvik AB, 1984.
7. Buser, H-R
   Dissertation. University of Umeå, 1978.
8. Warman, K
   Report MKS-84/54. Environmental Consultants at Studsvik AB, 1984.
9. Bergström, J G T
   Report EB-83/124. Studsvik Energiteknik AB, 1983.

Reprinted from Chemosphere, Volume 15, Öberg, T., Bergström, J., Combustion test data from a Swedish hazardous waste incinerator, Pages No. 2045-2048, Copyright (1986), with permission from Elsevier Science. Single copies of the article can be downloaded and printed for the reader's personal research and study.

DOI: 10.1016/0045-6535(86)90510-2