N-doped TiO2 nano particles for photocatalytic degradation of coliform and fecal coliform from hospital wastewater effluent

The photocatalytic process as an advanced oxidation process (AOP) has gained worldwide attention in the water and wastewater industry. The photocatalytic process can be used for water and wastewater disinfection. The aim of this study was to remove coliforms and faecal coliforms from real hospital wastewater using UV and UV/N doped TiO2 photocatalytic process. Secondary wastewater samples were collected from Ali-ebne Abitaleb Hospital, Zahedan. The real wastewater samples containing N-doped TiO2 nanoparticles were exposed to UV light in a reactor. Multi-tube fermentation method (MPN/100ml) was used to count the coliform and faecal coliform bacteria and evaluate the process efficiency. The results showed that the mechanism of inactivation of coliforms and faecal coliforms by N-doped TiO2 nanoparticles and UV light followed the first-order equation, and the simultaneous application of N-doped TiO2 nanoparticles and UV light (N-doped TiO2/UV) increased the efficiency of the photocatalytic process and completely inactivated the coliforms and faecal coliforms in 10 minutes. The results of this study also showed that with increasing contact time, the removal efficiency of coliforms and faecal coliforms increased in the presence of UV light. The highest efficiency of the nanoparticles in bacterial inactivation was achieved at a dose of 120 mg/l in the presence of UV light and was 100%. The nano-photocatalytic process can be used as an efficient method to remove coliforms and faecal coliforms from hospital wastewater, and the N-doped TiO2/UV process is a reliable antibacterial method for water and wastewater disinfection.