Resistance of Fusarium sp spores to solar TiO₂ photocatalysis: influence of spore type and water (scaling-up results)

BACKGROUND: Common irrigation water disinfection methods, which may be unable to inactivate all types of pathogens or even become phytotoxic themselves, are not very effective in controlling phytopathogens. Water disinfection by photocatalysis is a promising irrigation-water treatment for destroying phytopathogens without the drawbacks of conventional disinfection methods. Previous research has shown that solar photocatalytic technology can be used in the disinfection treatment of bacteria, protozoa and fungi, either through solar disinfection only. The purpose of this work was evaluate the TiO₂ photocatalysis process to inactivate Fusarium spores in distilled and well water.

RESULTS: This paper reports on the ability of solar photocatalysis to inactivate Fusarium spores in a solar bottle reactor and in a new 60 L compound parabolic collector (CPC) prototype reactor. Inactivation of Fusarium sp spores by titanium dioxide (Degussa P25) was evaluated in distilled and natural well water. The experiments were carried out using 5 or 6 h exposure to natural sunlight at the Plataforma Solar de Almeria (Southeast Spain). The highest Fusarium spore inactivation rate during experiments was achieved with a 30 L min⁻¹ flow rate and 100 mg L⁻¹ TiO₂ concentration. Three different Fusarium spores (microconidia, macroconidia and chlamydospores) were individually evaluated to determine whether there were differences in resistance to the photocatalytic treatment. The results showed that chlamydospores were the most resistant, followed by macroconidia, and finally microconidia were the most sensitive.
CONCLUSIONS: Microconidia, macroconidia and chlamydospores in distilled and well water were inactivated with TiO₂ slurry in a 60 L CPC photoreactor, demonstrating for the first time that it is possible to scale-up photocatalytic treatment for use and reuse of water for irrigation.