Conclusion

The treatment of pharmaceutical residues by means of several AOPs is progressively receiving greater attention due to their efficacy and/or efficiency. Particularly, in the last decade the electrochemical technologies have proven to be an efficient, versatile alternative. The EAOPs, especially those based on the electrogenerated Fenton's reagent (H2O2+Fe2+) such as the EF and SPEF processes, have been the most applied electrochemical decontamination processes for the treatment of synthetic aqueous solutions containing pharmaceutical residues. These methods exhibit high oxidation ability due to the generation of 'OH in the bulk from the Fenton's reaction between cathodically electrogenerated H2O2 and added iron catalyst. The • OH radical is able to lead very quickly to the cleavage of the aromatic rings as well as to the progressive oxidation of most of the aliphatic carboxylic acid by-products. However, the formation of some refractory carboxylic acids requires the use of UV radiation from artificial lamps or sunlight, and/or the use of high oxidation power anodes to take advantage of the anodic oxidation process based on the role of heterogeneous •OH radical. On the other hand, the real hospital and pharmaceutical wastewaters have been mostly treated by electrochemical oxidation with "non active" anodes such as BDD and electrocoagulation. Since these wastewaters usually contain Cl- ion, the electro-oxidation process usually proceeds via the formation of active chlorine species, thus being interesting the use of "active" anodes such as Ti/RuO. . Other technologies such as the internal micro-electrolysis and PEC have been less documented for the treatment of these pollutants and need more research for its thorough understanding. In summary, the use of renewable energy sources to power the processes is priority to enhance the sustainability of all these electrochemical treatments. This can definitely increase the acceptance of the electrochemical technologies, as it is foreseen in the case of the SPEF. This latter method is probably the most promising technology among those explained in this chapter.

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