Photocatalytic antibacterial effect of chemisynthesized Titania nanoparticles against <i>E. coli</i> in a synthetic matrix resembling animal slaughterhouse effluent

ABSTRACT Wastewater generated from animal slaughtering is discharged into rivers without adequate treatment, causing diseases, as it is used for agricultural irrigation and as drinking water for animals. In this context, this research proposed two treatment steps to evaluate the reduction of the high bacterial load of Escherichia coli in slaughterhouse wastewater using titania nanoparticles (TiO2-NPs) synthesized by chemical precipitation, evaluating the dose and contact time. TiO2-NPs, characterized by scanning electron microscopy, exhibited sizes from 16 to 100 nm in diameter, with vibrational bands of 429.01 cm−1 before and 420.25 cm−1 after photocatalytic treatment (O–Ti–O mode) according to Fourier transform infrared analysis and a BET surface area of 64.719 m2 g−1. The first stage consisted of pretreating wastewater with H2O2 and FeCl3, which contained 2.0 × 104 CFU mL−1 (5.35 McFarland) of E. coli, reducing the bacterial density by 28.22%. In the second stage, photocatalysis with TiO2-NPs was applied using UV lamps (253.80, 313.04, and 365.44 nm) on a synthetic matrix with a concentration of E. coli equivalent to that of the water after pretreatment (1.44 × 104 CFU mL−1 or 3.84 McFarland), achieving 97.31% removal using 1 g of TiO2-NPs in 25 mL of sample for 120 min.