Inactivation by solar photo-Fenton in pet bottles of wild enteric bacteria of natural well water: Absence of re-growth after one week of subsequent storage

Iron photo-assisted inactivation of wild enteric bacteria (total coliforms/E. coil and Salmonella spp.) was carried out in water from the Sahelian wells having different pH (W1:4.9 and W2: 6.3) and a natural iron content of 0.07 mg/L We evaluate the efficiency of the disinfection on different systems containing both or only one Fenton reagent (H2O2/Fe-2.): (i) H2O2/Fe2+/hv, (ii) Fe2+/hv, (iii) H2O2/hv, and (iv) only light irradiation (hv) at lab and field scale. Generally, 0.6 mg/L of Fe2+ and/or 8.5 mg/L of H2O2 were used in the Fenton reagent. The systems H2O2/Fe2+/hv and H2O2/hv led to total inactivation of Salmonella and E. coil. The natural iron content (0.07 mg/L) was enough to drive an efficient photo-Fenton process leading to total bacterial inactivation. Our results show that: (i) the iron salt present in Sahelian water is enough to perform a photo-Fenton disinfection of drinking water when adding H2O2, (ii) addition of external iron salts at near neutral pH has no additional effect on the bacterial photo-Fenton inactivation process. After one week of storage, no enteric bacteria re-growth was observed in treated waters. Mechanistic suggestions are presented to explain the observed results. (C) 2012 Elsevier B.V. All rights reserved.