Particulate phase emission of parent polycyclic aromatic hydrocarbons (PAHs) and their derivatives (alkyl-PAHs, oxygenated-PAHs, azaarenes and nitrated PAHs) from manually and automatically fired combustion appliances

Abstract

Residential biomass combustion may represent a significant emission source of polycyclic aromatic hydrocarbons (PAHs) and derivatives, some of which are known for their toxicity. In this study, a manually operated batch stove (burning wood logs) and an automatic pellet stove were selected to carry out combustion experiments. Two types of firewood (pine and eucalypt) were used as fuels in the manual stove. Four types of pellets and three agricultural fuels (olive pit, almond shell and shell of pine nuts) were selected for the automatic stove. The particulate matter (PM10) samples from the exhaust flue gas were solvent extracted and analysed for 26 parent and alkyl-PAHs, 15 nitrated PAHs (NPAHs), 15 oxygenated PAHs (OPAHs) and 4 azaarenes (AZAs) by gas chromatography–mass spectrometry. The global parent PAH emission factors (EFs) for the pellet stove ranged from 0.046 to 0.51 mg kg−1 of fuel burned, dry basis (db). The EFs obtained for the manual stove varied from 0.33 to 1.97 and from 8.65 to 24.3 mg kg−1 (db) for the combustion of eucalypt and pine, respectively. The devolatilisation phase of softwood in the latter appliance is critical because benzo[a]pyrene emissions can be more than 1,000 times higher than the values observed for any other combustion stages, appliance or biofuels. As for parent PAHs, it was observed that emissions of OPAHs, NPAHs and AZAs vary greatly depending on either the biofuel or the combustion technology.