and thermophilic anaerobic digesters to remove various TrOCsincluding musks, antibiotics, and hormones. It is possible that theozone dosage utilised by Carballa et al. [8] was too low to impactTrOC removal. In that study, ozone pre-treatment was only ben-eficial to the removal of carbamazepine because it preferentiallypartitioned on the aqueous phase of sludge and was amenable toozone treatment [8]. Qiang et al. [141] observed that ozone treat-ment of sludge at 0.1 g O3/g TS resulted to the desorption andcomplete removal of estrone, estriol, and 17-ethinylestradiol, butonly to a moderate removal of bisphenol A and nonylphenol due totheir strong binding with sludge. This suggests that it is easier forozone to attack dissolved TrOCs than sorbed TrOCs. Compared toQiang et al. [141], Lahnsteiner and Vranitzky [140] observed higherremoval of nonylphenol because they utilised sludge containinglower concentrations of nonylphenol and nonylphenol ethoxylates.Their study also demonstrated an 18–60% increase in the removal ofpolycyclic aromatic hydrocarbons from sludge when ozone dosagewas increased (0.021–0.081 g O3/g TS).