Chapter 6: Action Mechanisms of Electro-Fenton and Photo-Electro-Fenton Processes for Pathogen and Organic Microcontaminant Removal Check Access

The photo-Fenton process has been widely studied as a tertiary treatment for the degradation of microcontaminants along with the disinfection of pathogenic microorganisms. However, its combination with other technologies can increase the yield of the treatment thus increasing the feasibility of a real application at larger scale. In this sense, electrochemical processes pose an interesting complement for photo-Fenton since reagents could be electro-generated on the electrode surface, saving the risks and costs of storage and transport. The application of photo-electron-Fenton processes presents a series of advantages, which can be detrimental for the microbial life cycle. As a result, such treatments combine the synergistic generation of highly oxidative disinfecting species, less oxidative but germicidal ROS (i.e. H₂O₂), and unfavourable conditions for microbial survival. The complex mechanism of microorganism disinfection is further discussed in this chapter, elucidating the various pathways and exploitable aspects that lead to their inactivation via electro-oxidation processes or even electro-Fenton when H₂O₂ is electro-generated in the bulk reaction. Finally, the pitfalls and limitations of upscaling the photo-electro-Fenton (PEF) processes are presented and the effect of operational parameters in the PEF performance for microcontaminant and microorganism abatement is further discussed.