UV wastewater disinfection experiments were carried out on line after the settling tank using a collimated UV radi- ation (254 nm wavelength) equipment (International Light Technologies, Mod. IL 1400BL) equipped with a UV radiometer (International Light Technologies, Mod. SEL 240/NS254/TD). Different contact times were tested by varying the water flow (0.16, 0.32 and 0.5 L/s) through the UV disinfection equipment; the total radiant energy was controlled by the pump rate. Two different fluencies (8.5 and 12 mJ/cm2), corresponding to 15 and 30 L/min, respectively, were tested. Different pH values (from 5 to 9), adjusted with H2SO4 (0.5 M) or NaOH (0.5 M), depending on the desired initial pH value, were also assessed to determine the influence of this parameter on the disinfection efficiency.