The photo-Fenton process is an advanced oxidation process that uses the hydroxyl radical to disinfect and decontaminate water. Its non-selectivity makes it ideal for the removal of a range of microorganisms including those with antimicrobial resistance. Optimum parameters such as pH, temperature, hydrogen peroxide and iron concentrations and the intensity and wavelength of light irradiation are important to carry out an efficient photo-Fenton process. Traditionally photo-Fenton has been carried out at low acidic pH to obtain greater efficiency, but recent studies have been performed at near neutral. The current review examines the effectiveness of the photo-Fenton process at a near neutral pH for the disinfection of water. The optimal pH was seen to be at 2.8, with the efficiency of the photo-Fenton process decreasing as the pH rises. The optimal reagent concentrations showed considerable variation depending on the iron catalyst used and the iron to hydrogen peroxide concentration used. The effect of irradiance and temperature showed improved efficiency with higher levels. Different types of microorganisms such as E. coli, Pseudomonas sp., Enterococcus faecalis, Klebsiella pneumonia, Salmonella spp., total Coliforms, MRSA, MSSA, B. subtilis, Clostridium sp., Faecal Coliform, MS2 coliphage and Curvularia sp. are also examined and the effect the process will have on them. The design of reactors, such as compound parabolic reactors are also examined. The impact of light sources, including the recent reports on LEDs, on the production of hydrogen peroxide and thereby the improvement in the overall photo-Fenton disinfection is also discussed in detail. Finally, a techno-economic analysis to explain various costs associated with photo-Fenton process has also been carried out. It is concluded that the development of new heterogeneous supported immobilised catalysts that could work at the near neutral pH is an area, which requires considerable future research.
ASJC Scopus subject areas