EMISSIONS OF POLYCHLORINATED DIBENZO-P-DIOXINS AND DIBENZOFURANS IN FLUE-GAS FROM COCOMBUSTION OF MIXED PLASTICS WITH COAL AND BARK

Emissions caused by four different kinds of fuel mixtures of coal, bark, non-chlorinated and chlorinated waste plastic material were compared. The combustion tests were performed at a municipal district heating boiler as a full scale experiment. Our results prove the evidence for conversion of chlorinated plastic material to polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). The response of additives in plastics, especially copper, to the formation of PCDDs and PCDFs as a catalyst was clear. However, the total PCDD and PCDF emissions as Nordic toxic equivalents (TEQs) from co-combustion of mixed plastics related to municipal solid waste was only 38.4 pg/Nm3. This value was clearly below the proposed EC standard 0.1 ng TEQ/Nm3. Emissions from combustion of coal and bark were 16.4 pg TEQ/Nm 3 which increased to 23.2 pg TEQ/Nm3 with co-combustion 4.1% (w/w) of non-chlorinated plastics in fuel mixture.