The inactivation of phages MS2, ΦX174 and PR772 using UV and solar photocatalysis

The photolytic and photocatalytic disinfection of three bacteriophages (MS2, ΦX174 and PR772) under both artificial UV irradiation and natural sunlight was studied. A large variation was seen in the relative responses of phages to the two light sources, while solar photocatalysis showed promising disinfection capabilities for all three phages. Under artificial UV, the resistance of phages to both photolytic and artificial treatment was found to decrease in the following order: PR772 > ΦX174 > MS2. Indeed, 3-log inactivation of PR772 was not achieved after 25 h of illumination in either the absence or presence of catalyst. Under solar treatment, PR772 was inactivated far more readily, 3-log inactivation being achieved within an hour in the presence of catalyst in two trials. It is thought that the variation in solar intensity during the trials had a major effect on disinfection rates, as kinetics for phages varied considerably under different weather conditions.