Photoelectrocatalytic inactivation of the waterborne emerging parasite Cryptosporidium in peroxymonosulfate solutions

Cryptosporidium is a protozoan parasite that generally infects the epithelium of the gastrointestinal tract of various vertebrate hosts, including humans, in which cause cryptosporidiosis. Infection is transmitted by the faecal-oral route and can be acquired by direct contact with infected hosts or indirectly by consumption of water and/or food contaminated with oocysts (infecting parasitic form). Although in healthy people cryptosporidiosis may be self-limiting with a duration of 3-4 days, in children and immunocompromised patients it causes severe disease and can lead to death. Cryptosporidiosis is considered an emerging disease and, since 2004, it has been included in the "Neglected Diseases Initiative", by the World Health Organisation (WHO) due to its high morbidity and mortality and the socioeconomic consequences that link it to the poorest communities on the planet. Thus, this disease is responsible for 30-50% of infant mortality in developing countries. Advanced oxidation processes (AOPs) have been recognised as highly effective techniques for the mineralisation of organic compounds as well as for the inactivation of pathogens in aqueous media. Photoelectrocatalysis (PEC) consists of the immobilisation of a photocatalyst on an electrode that will act as a photocathode or photoanode. When an external electric potential is applied, the induced charge separation leads to higher efficiency. At the photo-electrode/water interface under irradiation, a series of chemical reactions occur resulting in the generation of reactive oxygen species (ROS) such as hydroxyl radicals (HO•), superoxide radicals (O2•), hydroperoxide radicals (HO2•), hydrogen peroxide (H2O2), which further oxidise organic matter or inactivate pathogens in water . To our knowledge, the investigation of the ability of this process to inactivate Cryptosporidium oocysts is completely unknown, representing a new technology to be evaluated in them inactivation of this parasitic protozoan.