BACKGROUND: Although chlorination is an effective and widely employed method of water disinfection, it suffers serious drawbacks such as the formation of toxic chlorinated by-products. Therefore, other disinfection technologies have been researched and developed, including advanced oxidation. RESULTS: The efficacy of heterogeneous photocatalysis and sonophotocatalysis induced by UV-A irradiation and low frequency (24-80 kHz) ultrasound irradiation in the presence of TiO2 as the photocatalyst and peracetic acid (PAA) as an additional disinfectant to inactivate E. coli in sterile water was evaluated. PAA-assisted UV-A/TiO2 photocatalysis generally leads to nearly complete E. coli inactivation in 10-20 min of contact time with the extent of inactivation depending on the photocatalyst type and loading (in the range 100-500 mg L-1) and PAA concentration (in the range 0.5-2 mg L-1). The simultaneous application of ultrasound and UV-A irradiation in the presence of TiO2 and PAA prompted further E. coil inactivation. CONCLUSIONS: The proposed advanced disinfection technology offers complete E. coil inactivation at short treatment times and low PAA doses. (C) 2010 Society of Chemical Industry