PAH EMISSION FROM THE INCINERATION OF WASTE OILY SLUDGE AND PE PLASTIC MIXTURES

A batch-type, controlled-air incinerator was used for the treatment of oily sludge and polyethylene (PE) plastic mixtures. The concentration and composition of 21 individual PAHs (polycyclic aromatic hydrocarbo ns) in the raw wastes, flue gas (gas and particle phases) and ash were determined. Stack flue-gas samples were collected by a PAH stack-samp ling system. Twenty one individual PAHs were analyzed primarily by a g as chromatograph and a gas chromatography/mass spectrometer. Due to in complete combustion, PAH content in the feeding wastes have a strong i nfluence on PAH emission in both stack flue gas and ash residue. With the oily sludge in the feeding waste mixtures, the input mass of lower molecular weight PAHs - Nap, AcPy, Acp, Flu, PA, Ant and FL - was con tributed mainly by liquid diesel, while the input mass of higher molec ular weight PAHs - Pyr, CYC, CHR, BbF, BkF, BeP, BaP, PER, IND, DBA, B bC, BghiP and COR - was primarily contributed by the oily sludge. For the distribution of individual PAH mean output mass, lower molecular w eight PAHs - Nap, AcPy, Acp and Flu - have > 87% of their mass dischar ged by the stack flue gas. However, the higher molecular weight PAHs - Ant, FL, CHR, BbF, BeP, BaP, PER, IND, DBA, BbC, BghiP and COR - have significant mass fractions (>18%) discharged by the ash residue. The total-PAH output/input mass ratios were between 0.00103 and 0.00360 an d averaged 0.00203. This result indicated that the depletion of PAH ma ss in the combustion process was very significant The PAH content in t he fuel during the combustion process is the control factor of PAH emi ssion. The co-combustion of oily sludge with plastic is a potential me thod of reducing the PAH emission and of saving the consumption of aux iliary fuel.