Levels of polycyclic aromatic hydrocarbons in the bio-oils from induction-heating pyrolysis of food-processing sewage sludges

This study investigated the distribution of 21 target polycyclic aromatic hydrocarbons (PAHs) in the bio-oils, which were produced during the induction-heating pyrolysis of three different food-processing sewage sludges. The total concentrations of these priority PAHs ranged from 298 to 336 mg L−1. The levels of PAHs are relatively high in low molecular weight fractions such as naphthalene, acenaphthylene, acenaphthene, fluorene and pyrene, and high molecular weight fractions such as indeno[1,2,3-cd]pyrene and dibenz(a,h)anthracene. However, in consideration of carcinogenic potency, it was found that dibenz(a,h)anthracene comprised a significant proportion of toxic equivalency values for target PAHs present in the bio-oils as a basis for using toxic equivalency factor method.