Photodynamic processes for water and wastewater treatment: a review

Photodynamic therapy (PDT) has been widely employed in clinical applications, healthcare, and public health (e.g. cancer research, microbiological control, vector control, etc). The photodynamic action is an advanced oxidation process based on the production of reactive oxygen species (ROS) and singlet oxygen by the excitation of a photosensitizer by specific wavelengths of light in the presence of molecular oxygen. The generation of ROS, which are highly reactive, encourages the use of PDT against recalcitrant pollutants and resistant parasites, a novel approach for PDT applications. Here, we explored recent research in PDT in water and wastewater treatment, elucidating operational conditions, main targets, potentials, and constraints, considering a collection of scientific papers curated by a well-defined research strategy. Retrieved records were filtered by subjects, and data was organized into a content network. Results showed that PDT is a timely alternative to deal with emerging chemical contaminants, resistant microorganisms, and other challenges, raising opportunities for versatile applications and sustainable solutions. Advances in environmental applications of PDT may help reach the Sustainable Development Goal 6 (SDG 6), but also positively impact other SDGs.