This lecture illustrates Fenton processes for water treatment, types of Fenton processes, homogeneous and heterogeneous Fenton processes, extended Fenton processes, Fenton-like processes, ozone treatment processes, properties of ozone, decomposition of ozone in water, ozone-based AOPs, O3/H2O2 (Peroxone) process, photolytic ozonation: O3/UV process, catalytic wet peroxide oxidation (CWPO), and performance of CWPO.