Urban secondary effluents (treated sewage) have non-biodegradable contaminants, which makes it difficult to remove them by conventional methods.Advanced oxidation processes (AOPs) are processes with great potential (E ° = 2.02) to produce hydroxyl radicals (HO • ).They are highly oxidizing species capable of mineralizing organic matter and recalcitrant compounds.The objective of this work was to optimize the treatment process (Photo-Fenton), to study the influence of interfering compounds on the treatment of secondary effluent disinfection by the Photo-Fenton (H2O2 / UV / Fe 2+ ) method, of the pilot plant of water treatment of the school of technology the Universities of Campinas, Limeira.The optimization of the operational variables of the system ([H2O2], [Fe 2+ ], [MB]), was used the experimental Planning models of the Doehlert Matrix and the Rotatable Central Composite Design, a three-variable model was used in two levels using matrices of coefficients of contrasts with variables coded for each model, these optimal results were confirmed using Pareto graphs and the response surface method, the application of the optimized variables was performed in the treatment and disinfection of the secondary effluent, obtaining a reduction of more than 4 logs in the total levels of coliforms and 6 logs for E-Coli at the end of 60 minutes of treatment.In the following tests the influence of interfering compounds on disinfection (nitrate and carbonate metals) in controlled concentrations was tested.These compounds were inserted into the effluent, in the tests on metals it was found that the maximum concentrations of Lead, Zinc, Nickel, Iron and Chromium reduce the efficiency in disinfection but Copper and Aluminum and the mixture of metals together do not interfere and contribute significantly in the disinfection process, in the tests with Carbonates and Nitrates, it was verified that in the case of Nitrate and the mixture of the two compounds do not interfere in the disinfection but the presence of Carbonates reduces the efficiency of the process.