Overview of toxic cyanobacteria and cyanotoxins in Ibero-American freshwaters: Challenges for risk management and opportunities for removal by advanced technologies

The increasing occurrence of cyanobacterial blooms worldwide represents an important threat for both the environment and public health. In this context, the development of risk analysis and management tools as well as sustainable and cost-effective treatment processes is essential. The research project TALGENTOX, funded by the Ibero-American Science and Technology Program for Development (CYTED-2019), aims to address this ambitious challenge in countries with different environmental and social conditions within the Ibero-American context. It is based on a multidisciplinary approach that combines ecology, water management and technology fields, and includes research groups from Chile, Colombia, Mexico, Peru and Spain. In this review, the occurrence of toxic cyanobacteria and cyanotoxins in freshwaters from these countries are summarized. The presence of cyanotoxins has been confirmed in all countries but the information is still scarce and further monitoring is required. In this regard, remote sensing or metagenomics are good alternatives at reasonable cost. The risk management of freshwaters from those countries considering the most frequent uses (consumption and recreation) has been also evaluated. Only Spain and Peru include cyanotoxins in its drinking water legislation (only MC-LR) and thus, there is a need for regulatory improvements. The development of preventive strategies like diminishing nutrient loads to aquatic systems is also required. In the same line, corrective measures are urgently needed especially in drinking waters. Advanced Oxidation Processes (AOPs) have the potential to play a major role in this scenario as they are effective for the elimination of most cyanotoxins classes. The research on the field of AOPs is herein summarized considering the cost-effectiveness, environmental character and technical applicability of such technologies. Fenton-based processes and photocatalysis using solar irradiation or LED light represent very promising alternatives given their high cost-efficiency. Further research should focus on developing stable long-term operation systems, addressing their scale-up.