The term emergent contaminants (EC) is generally used to refer to compounds of various origins and chemical nature, whose presence in the environment is not considered significant in terms of distribution and / or concentration, and therefore they are not noticed. However, they are now being widely detected and have the potential to develop an ecological impact as well as adverse health effects (Barceló D. and López M.J., 2007; Stuart M. et al., 2012). Among the ECs present in the water, we can highlight drugs, per fluorinated compounds, hormones, drugs, and personal care products.
These contaminants are concentrated in variable concentrations throughout the SUDOE space, being, therefore, a generalized environmental problem. For example, Andreu V. et al. (2016) detected levels of ibuprofen and codeine of 4.8 and 1.2 ng / L with maximums of 59 ng / L and 63 ng / L, respectively, in Mediterranean wetlands. Lolic et al. (2015), for their part, detected traces of acetaminophen, ketoprofen, hydroxybuprofen and carboxyibuprofen in maximum concentrations of 584, 89.7, 287 and 1227ng / L in the waters of the north coast of Portugal, respectively.
The main source of these compounds into the aquatic environment are wastewater, although agriculture and livestock are also contaminated with pesticides and antibiotics, respectively. In most cases their disposal at conventional wastewater treatment plants is not complete. Nowadays, there are new and more effective technologies for its elimination, from the most well-known ones such as the membrane bioreactors to others of greater cost like reverse osmosis, the microfiltration or the processes of advanced oxidation. However, the application of this type of technology supposes a high cost in the treatment of water that still few companies that manage water services are willing to assume.
Moreover, with these technologies a complete mineralization of the contaminant (production of more harmful secondary metabolites) is not achieved at all. Therefore, it is necessary to look for new techniques that allow, on the one hand, to completely degrade these organic compounds and, on the other hand, reduce the costs of regeneration associated with the treatment of residual water for its subsequent reuse. This is the main object of the 4KET4Reuse project.