Within wastewater treatment plants, hydrophobic micropollutants such as Polycyclic Aromatic Hydrocarbons (PAHs) concentrate into sludge. As a consequence, their removal during anaerobic digestion largely impacts the suitability of digested sludge for agricultural disposal and is an important issue. In previously published studies, these removals have been shown to be influenced by sorption, throughout bioavailability limitation towards biodegradation, and cometabolism. In this study, the Michaelis-Menten formalism was modified to (i) consider the concentration of PAH-metabolizing biomass as a constant; (ii) assume that PAH concentrations in sludge was below half saturation constant; (iii) take into account the cometabolic interactions and (iv) the limitation by bioavailability. The confrontation of the obtained formalism to experimental data was based on four anaerobic continuous bioreactors fed with various sludge assuming different levels of bioavailability and cometabolism. Our results first demonstrated that the proposed formalism was suitable to model the biodegradation of PAHs. In addition, it was shown that the free and sorbed-to-dissolvedand- colloidal-matter PAHs are bioavailable to sludge microorganisms. Furthermore, the dry matter degradation rate was found to be a relevant criterion to represent the cometabolic potential of sludge substrate. Finally, it was shown that both bioavailability and cometabolism influence anaerobic PAH biodegradation in a significant way.