Ozone-based advanced oxidation processes (AOPs), recognized as effective methods for tertiary water treatment in view of trace organic contaminant (TrOC) removal, were investigated in this study. By assessing and comparing different ozone-based AOPs for TrOC degradation in secondary wastewater effluent, criteria for appropriate AOP application and oxidant dose are provided. In this study, the value of the minimum ozone demand for formatted hydroxyl radical ((OH)-O-center dot) to react with target contaminants was proposed and determined. The ozone exposure and (OH)-O-center dot exposure were systemically investigated and compared in four types of different ozone-based AOPs (i.e., O-3 only, O-3/H2O2, O-3/UV, and O-3/H2O2/UV). The significant increase in (OH)-O-center dot exposure was achieved by means of adding H2O2 and/or UV, which results in the increase of the eliminant efficiency of TrOCs. In particular, ozone-resistance compounds (e.g., atrazine and alachlor) were removed more efficient by combination O-3 with H2O2 and UV than O-3 only, O-3/H2O2 and O-3/UV at the equal ozone dose. Such as, the removal of atrazine and alachlor tripled after 2 min of treatment in the effluent by combining O-3 with H2O2 and UV. Among the four ozone-based AOPs, the highest ozone exposure (3.27 mg min/L) was achieved by applying an O-3:DOC of 0.9 O-3 only. High ozone exposure is beneficial to enhance the abatement efficiency of high ozone-selective compounds (e.g., pentachlorophenol).