**5. Conclusions and final comments**

The use of solar radiation to catalyze Fenton-like processes has been proven to be effective to deactivate waterborne pathogens. Experimental results and reported deactivation parameters suggest that these processes could be an interesting alternative to conventional chlorine disinfection for developing countries. Furthermore, solar-driven Fenton-like processes is a more efficient alternative when compared to conventional solar disinfection (SODIS), since the required exposure times for both are significantly different and much lower for the photocatalytic arrangement. Nevertheless, it is well documented that for solar photocatalysis to perform at optimum conditions, a primary treatment of raw water might be needed in order to decrease the concentrations of interfering compounds such as natural organic matter. When considering the necessity to provide a disinfectant residual in order to protect water treated with AOPs, sequential disinfection using AOPs as a primary process coupled with secondary free chlorine also represents an interesting alternative for developing countries. Similar to the synergistic effects produced by ozone on secondary free chlorine deactivation of strong microorganisms such as *C. parvum* oocysts, preliminary studies conducted with AOPs used as primary disinfectant –instead of ozone- have reported to generate similar synergistic effects on the deactivation of conservative surrogates such as *B. subtilis* spores and helminth eggs. More comprehensive work needs to be conducted in order to fully characterize the magnitude and occurrence of this synergism under a wide range of experimental conditions of interest for drinking water treatment such as water pH and temperature. Finally, in order to fully understand the effectiveness of solar-driven Fenton-like processes when used for disinfection purposes, it is clear that more studies are required in order to elucidate the actual mechanism of cell deactivation when using such processes.

### **6. References**


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