Disinfection of Outdoor Livestock Water Troughs: Effect of TiO2-Based Coatings and UV-A LED

Abstract

The control of pathogens is of great importance to maintaining safe water quality for animal consumption and reducing the spread of pathogens in the environment and throughout the production chain. Titanium dioxide (TiO2) is an attractive nanoparticle for disinfection purposes because it is easy to use, highly effective under UV radiation and cost effective. The goal of this study was to assess the disinfection effectiveness of TiO2-coated materials (high-density polyethylene, HDPE and stainless steel, SS) and UV-A LED light of non-coated materials, and the impacts of temperature and bacteria concentration in disinfection. Three TiO2 composites, two synthesized and one commercial (namely, TiO2, Ag- TiO2 and P25 TiO2), were assessed for their removal photocatalytic efficiency of methylene blue (10 mg/L). P25 TiO2 showed fast photocatalytic efficiency after two hours of treatment, reaching 98% efficiency after 4 h. The immobilization method M1 (fast cured epoxy) of particles in the material showed the best adhesion to substrates (scale = 4 ASTM D 3359) and for TiO2-coated stainless steel in a pre-disinfection test at a temperature of 32.3 °C and efficiency of 55.2%. There were statistically significant differences in disinfection treatments between of TiO2-coated and non-coated materials under the influence of UV-A LED light (p < 0.05) at a control temperature of 26 °C. The resulting disinfection efficiencies for typical trough materials (coated (C) or non-coated (NC) HDPE; and SS) were ranked as follows: SS-C-Light (100%) > SS-Light (81.4%) > HDPE-C-Light (63.9%) > HDPE-Light (51.3%). High ambient temperature and initial bacteria concentration tended to reduce the disinfection efficiency. The presence of TiO2 on the coated surface was confirmed using a scanning electron microscope (SEM) and energy dispersive X-ray microanalyses (EDS). These results demonstrate the disinfection potential of TiO2-coated materials and UV-A LED light, and thus, they should be considered as valuable alternatives to deal with persistent E. coli contamination of cattle troughs.