Comparison of O3, UV/O3, and UV/O3/PS processes for marine oily wastewater treatment: Degradation performance, toxicity evaluation, and flocs analysis

•Light and heavy crude oils and three O3-based processes were examined/compared.•UV/O3/PS process removed more than 90% of crude oils in 30 min.•100% of the n-alkanes and PAHs and over 90% of TOC were removed in 1 h in UV/O3/PS process.•Acute toxicity of effluent to Vibrio fischeri and Artemia franciscana was significantly reduced.•Flocs characterization revealed the fate of insoluble components during oxidation.