Water disinfection using photo-Fenton: Effect of temperature on Enterococcus faecalis survival

The photo-Fenton process is a promising alternative to classical water disinfection treatments, although information in this regard is scarce due to its operational limitations. The effect of temperature (10, 20, 30 and 40 degrees C) was studied on water disinfection using the photo-Fenton reaction at initial near neutral pH with resorcinol as a model of natural organic matter (NOM). Enterococcus faecalis, a Gram-positive microorganism, was selected as an indicator of wastewater faecal contamination. The individual effects of different variables involved in this process (mechanical stress, UVA, H2O2, Fe2+, H2O2/Fe2+, UVA/Fe2+, UVA/H2O2 and UVA/H2O2/Fe2+) were determined. UVA and H2O2 led to a 2.5-log decrease individually and the combined effect of both variables managed to disinfect up to the detection limit (i.e. from a 5.5 to a 6-log reduction) over the same treatment time. Only by adding 10 mg L-1 of Fe2+, the inactivation time was reduced from 120 min (H2O2/UVA) to 80 min (H2O2/UVA/Fe2+; photo-Fenton) with 120 mg L-1 of H2O2. A higher disinfection result for E. faecalis was observed by increasing temperature according to the Arrhenius equation in the photo-Fenton process. The detection limit was not reached at 10 degrees C and, to achieve the detection limit at 20, 30 and 40 degrees C, 80, 65 and 40 min were needed, respectively. The decrease in treatment time is a key factor in applying the photo-Fenton disinfection process to a wastewater treatment plant. (C) 2012 Elsevier Ltd. All rights reserved.