Disinfection of anaerobically treated municipal wastewater was done using ozone, UV, H₂O₂, peracetic acid, and advanced oxidation processes (O₃/H₂O₂, O₃/UV, H₂O₂/UV, H₂O₂/sunlight). Ozone, UV irradiation, and H₂O₂ eliminated 99% of pathogens (total coliform, fecal coliform, and E. coli) at ozonation time of 20 min at the rate of 1000 mg/hr; UV irradiation time of 11 min and H₂O₂ dose of 336 mg/L. The use of combined systems (H₂O₂/sunlight) is especially promising due to the synergistic effect and cost efffectiveness. Regrowth of pathogens increased with increase in time and temperature (from 15 to 35ºC). The presence of nutrients and fluorescent light enhanced the rate of reactivation of pathogens.