Distribution of 16 EPA-priority polycyclic aromatic hydrocarbons (PAHs) in sludges collected from nine Tunisian wastewater treatment plants

Polycyclic aromatic hydrocarbons (PAHs) are organic compounds which may be present as contaminants in wastewater sewage sludge. Due to their toxicity and persistence in the solid phase, information should be gathered relating to their presence in sewage sludge in order to determine their contamination risks after land application. In this study, sewage sludge samples from nine Tunisian wastewater treatment plants (WWTPs) were characterized for the total content in 16 EPA-priority PAHs using an optimized extraction protocol. These WWTPs differ in the type of applied treatment and the wastewater source. Through this first assessment of PAHs in Tunisian sludges, their total concentration varied from 96 to the highest level of 7718 ng g(-1). Regardless of the source of wastewater, the highest PAH content was found in sludges deriving from untreated wastewater (natural lagooning). In addition, some correlation was found between the distribution patterns of each PAH, the type of applied treatment on one hand and the wastewater source on other hand.