Mathematical model for the elimination of algae and cyanobacteria in eutrophic waters by using different oxidizing agents

Many bodies of water around the world are eutrophic and present cyanobacterial blooms. Oxidation techniques with ozone and UV radiation have been shown to be effective in laboratory conditions with controlled cultures, but studies with eutrophicated natural waters (non-laboratory conditions) are still lacking. Therefore, the main objective of the present work was to develop a mathematical model to determine the doses of different oxidizing agents [ozone (O₃), ultraviolet (UV) radiation at 254 nm and ozone-based advanced oxidation] to eliminate three photosynthetic organisms [Microcystis aeruginosa (MC), Anabaena (ANA) and Actinastrum] from a eutrophicated artificial lagoon. To this end, 24 physicochemical and biological water quality parameters were measured. Different equations were proposed to calculate the demand of the oxidizing agents to reduce the concentration of organisms to low risk levels, even in the presence of other pollutants. O₃ presented the best results by eliminating 100 and 88% of MC and ANA at a dose of 15 mg O₃/L. From the principal component analysis, it is observed that the main factor related to the reduction of turbidity was the destruction of the cells. Furthermore, this statistical analysis shows that the application of these oxidants produces an oxidation-release cycle of organic components because of cell lysis. This article presents for the first time a mathematical model that allows knowing the appropriate doses of different oxidants to eliminate this type of organisms in eutrophic waters, i.e., even in the presence of other types of ozone-consuming pollutants.