Disinfection of drinking water contaminated with Cryptosporidium parvum oocysts under natural sunlight and using the photocatalyst TiO2

The results of a batch-process solar disinfection (SODIS) and solar photocatalytic disinfection (SPCDIS) on drinking water contam- inated with Cryptosporidium are reported. Cryptosporidium parvum oocyst suspensions were exposed to natural sunlight in Southern Spain and the oocyst viability was evaluated using two vital dyes [40,6-diamidino-2-phenylindole (DAPI) and propidium iodide (PI)]. SODIS exposures (strong sunlight) of 8 and 12 h reduced oocyst viability from 98% (±1.3%) to 11.7% (±0.9%) and 0.3% (±0.33%), respectively. SODIS reactors fitted with flexible plastic inserts coated with TiO2 powder (SPCDIS) were found to be more effective than those which were not. After 8 and 16 h of overcast and cloudy solar irradiance conditions, SPCDIS reduced oocyst viability from 98.3% (±0.3%) to 37.7% (±2.6%) and 11.7% (±0.7%), respectively, versus to that achieved using SODIS of 81.3% (±1.6%) and 36.0% (±1.0%), respectively. These results confirm that solar disinfection of drinking water can be an effective household intervention against Cryptos- poridium contamination.