Recent advances in solar photochemical processes for water and wastewater disinfection

Photochemical processes for the treatment of water and wastewater have been receiving increasing attention as sustainable treatments involving a renewable, free and clean source of light, such as natural solar radiation. Different oxidative agents including hydrogen peroxide, peroxymonosulfate, persulfate, peracetic acid and free chlorine have been recently investigated as potential strategies to enhance the mere action of the solar photons for water disinfection.The aim of this study is to review the most recent advances reached in the scientific literature regarding these solar processess based on their promising capability to be further implemented in real field or industrial scale. The characterization of each oxidative agent, the efficiency of each solar photochemical process for disinfection of water and wastewater and the operating mechanism governing the microbial pathogens inactivation are discussed. Specific and complementary requirements of this type of applications such as the solar resource and the most promising solar reactors currently employed have been also described in detail. Finally, the main advantages, drawbacks, challenges and perspectives for their future implementation at full scale are also highlighted.