Solar disinfection of wild Salmonella sp. in natural water with a 18 L CPC photoreactor: detrimental effect of non-sterile storage of treated water

Abstract

For the first time solar disinfection of liters of water containing wild Salmonella sp. and total coliforms was carried out in a compound parabolic collector (CPC) photoreactor at temperatures of almost 50 C. Using surface water with high turbidity, this treatment was efficient in completely inactivating Salmonella sp. without regrowth during the subsequent 72 h of dark sterile storage. However if the solar treated water is poured in a non- sterile container, bacteria regrowth occurs even if 10 mg L1 of H2O2 is added before the storage. On the other hand, 30 mg L1 of H2O2 added when the irradiation started was completely depleted within 2 h and did not prevent bacterial regrowth during post-irradiation storage in non-sterile containers, demonstrating that storage of large volumes of water treated by solar irradiation was not optimal. Finally, total coliforms (Escherichia coli included) showed a far higher sensitivity than Salmonella sp. and demonstrated to be an inappropriate indicator for monitoring bacterial contamination in water during solar disinfection processes.